treewide: refresh kmalloc_obj() conversionsgrafted

This is another run of the Coccinelle script for converting kmalloc()
family of allocations to kmalloc_obj() via the existing rules in
scripts/coccinelle/api/kmalloc_objs.cocci

This catches both the set of kmalloc() uses added since the first
kmalloc_obj() conversions in v7.0 and adds a large group missed in the
first pass due to Coccinelle not interacting well with the cleanup.h
scoped_...() family of macros[1]. I worked around this with spatch's
"--macro-file" argument to a file with all the scoped_...() macros mapped
to Coccinelle's YACFE_ITERATOR[2] as that was the closest viable control
flow indicator I could find.

Build tested allmodconfig on x86, arm64, arm, loongarch, mips, powerpc,
riscv, and s390 with no new warnings.

Link: https://lore.kernel.org/lkml/202609021314.8A9C0B8@keescook/ [1]
Link: https://github.com/coccinelle/coccinelle/blob/master/standard.h [2]
Signed-off-by: Kees Cook <kees+treewide@kernel.org>

1 files changed, 10862 insertions, 0 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
new file mode 100644
index 000000000..3c10a0ef0
--- /dev/null
+++ b/fs/btrfs/inode.c
@@ -0,0 +1,10862 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2007 Oracle.  All rights reserved.
+ */
+
+#include <linux/kernel.h>
+#include <linux/bio.h>
+#include <linux/blk-cgroup.h>
+#include <linux/file.h>
+#include <linux/filelock.h>
+#include <linux/fs.h>
+#include <linux/fs_struct.h>
+#include <linux/pagemap.h>
+#include <linux/highmem.h>
+#include <linux/time.h>
+#include <linux/init.h>
+#include <linux/string.h>
+#include <linux/backing-dev.h>
+#include <linux/writeback.h>
+#include <linux/compat.h>
+#include <linux/xattr.h>
+#include <linux/posix_acl.h>
+#include <linux/falloc.h>
+#include <linux/slab.h>
+#include <linux/ratelimit.h>
+#include <linux/btrfs.h>
+#include <linux/blkdev.h>
+#include <linux/posix_acl_xattr.h>
+#include <linux/uio.h>
+#include <linux/magic.h>
+#include <linux/iversion.h>
+#include <linux/swap.h>
+#include <linux/migrate.h>
+#include <linux/sched/mm.h>
+#include <linux/iomap.h>
+#include <linux/unaligned.h>
+#include "misc.h"
+#include "ctree.h"
+#include "disk-io.h"
+#include "transaction.h"
+#include "btrfs_inode.h"
+#include "ordered-data.h"
+#include "xattr.h"
+#include "tree-log.h"
+#include "bio.h"
+#include "compression.h"
+#include "locking.h"
+#include "props.h"
+#include "qgroup.h"
+#include "delalloc-space.h"
+#include "block-group.h"
+#include "space-info.h"
+#include "zoned.h"
+#include "subpage.h"
+#include "inode-item.h"
+#include "fs.h"
+#include "accessors.h"
+#include "extent-tree.h"
+#include "root-tree.h"
+#include "defrag.h"
+#include "dir-item.h"
+#include "file-item.h"
+#include "uuid-tree.h"
+#include "ioctl.h"
+#include "file.h"
+#include "acl.h"
+#include "relocation.h"
+#include "verity.h"
+#include "super.h"
+#include "orphan.h"
+#include "backref.h"
+#include "raid-stripe-tree.h"
+#include "fiemap.h"
+#include "delayed-inode.h"
+
+#define COW_FILE_RANGE_KEEP_LOCKED	(1UL << 0)
+
+struct btrfs_iget_args {
+	u64 ino;
+	struct btrfs_root *root;
+};
+
+struct btrfs_rename_ctx {
+	/* Output field. Stores the index number of the old directory entry. */
+	u64 index;
+};
+
+/*
+ * Used by data_reloc_print_warning_inode() to pass needed info for filename
+ * resolution and output of error message.
+ */
+struct data_reloc_warn {
+	struct btrfs_path path;
+	struct btrfs_fs_info *fs_info;
+	u64 extent_item_size;
+	u64 logical;
+	int mirror_num;
+};
+
+/*
+ * For the file_extent_tree, we want to hold the inode lock when we lookup and
+ * update the disk_i_size, but lockdep will complain because our io_tree we hold
+ * the tree lock and get the inode lock when setting delalloc. These two things
+ * are unrelated, so make a class for the file_extent_tree so we don't get the
+ * two locking patterns mixed up.
+ */
+static struct lock_class_key file_extent_tree_class;
+
+static const struct inode_operations btrfs_dir_inode_operations;
+static const struct inode_operations btrfs_symlink_inode_operations;
+static const struct inode_operations btrfs_special_inode_operations;
+static const struct inode_operations btrfs_file_inode_operations;
+static const struct address_space_operations btrfs_aops;
+static const struct file_operations btrfs_dir_file_operations;
+
+static struct kmem_cache *btrfs_inode_cachep;
+
+static int btrfs_setsize(struct inode *inode, struct iattr *attr);
+static int btrfs_truncate(struct btrfs_inode *inode, bool skip_writeback);
+
+static noinline int run_delalloc_cow(struct btrfs_inode *inode,
+				     struct folio *locked_folio, u64 start,
+				     u64 end, struct writeback_control *wbc,
+				     bool pages_dirty);
+
+static int data_reloc_print_warning_inode(u64 inum, u64 offset, u64 num_bytes,
+					  u64 root, void *warn_ctx)
+{
+	struct data_reloc_warn *warn = warn_ctx;
+	struct btrfs_fs_info *fs_info = warn->fs_info;
+	struct extent_buffer *eb;
+	struct btrfs_inode_item *inode_item;
+	struct inode_fs_paths *ipath __free(inode_fs_paths) = NULL;
+	struct btrfs_root *local_root;
+	struct btrfs_key key;
+	unsigned int nofs_flag;
+	u32 nlink;
+	int ret;
+
+	local_root = btrfs_get_fs_root(fs_info, root, true);
+	if (IS_ERR(local_root)) {
+		ret = PTR_ERR(local_root);
+		goto err;
+	}
+
+	/* This makes the path point to (inum INODE_ITEM ioff). */
+	key.objectid = inum;
+	key.type = BTRFS_INODE_ITEM_KEY;
+	key.offset = 0;
+
+	ret = btrfs_search_slot(NULL, local_root, &key, &warn->path, 0, 0);
+	if (ret) {
+		btrfs_put_root(local_root);
+		btrfs_release_path(&warn->path);
+		goto err;
+	}
+
+	eb = warn->path.nodes[0];
+	inode_item = btrfs_item_ptr(eb, warn->path.slots[0], struct btrfs_inode_item);
+	nlink = btrfs_inode_nlink(eb, inode_item);
+	btrfs_release_path(&warn->path);
+
+	nofs_flag = memalloc_nofs_save();
+	ipath = init_ipath(4096, local_root, &warn->path);
+	memalloc_nofs_restore(nofs_flag);
+	if (IS_ERR(ipath)) {
+		btrfs_put_root(local_root);
+		ret = PTR_ERR(ipath);
+		ipath = NULL;
+		/*
+		 * -ENOMEM, not a critical error, just output an generic error
+		 * without filename.
+		 */
+		btrfs_warn(fs_info,
+"checksum error at logical %llu mirror %u root %llu, inode %llu offset %llu",
+			   warn->logical, warn->mirror_num, root, inum, offset);
+		return ret;
+	}
+	ret = paths_from_inode(inum, ipath);
+	if (ret < 0) {
+		btrfs_put_root(local_root);
+		goto err;
+	}
+
+	/*
+	 * We deliberately ignore the bit ipath might have been too small to
+	 * hold all of the paths here
+	 */
+	for (int i = 0; i < ipath->fspath->elem_cnt; i++) {
+		btrfs_warn(fs_info,
+"checksum error at logical %llu mirror %u root %llu inode %llu offset %llu length %u links %u (path: %s)",
+			   warn->logical, warn->mirror_num, root, inum, offset,
+			   fs_info->sectorsize, nlink,
+			   (char *)(unsigned long)ipath->fspath->val[i]);
+	}
+
+	btrfs_put_root(local_root);
+	return 0;
+
+err:
+	btrfs_warn(fs_info,
+"checksum error at logical %llu mirror %u root %llu inode %llu offset %llu, path resolving failed with ret=%d",
+		   warn->logical, warn->mirror_num, root, inum, offset, ret);
+
+	return ret;
+}
+
+/*
+ * Do extra user-friendly error output (e.g. lookup all the affected files).
+ *
+ * Return true if we succeeded doing the backref lookup.
+ * Return false if such lookup failed, and has to fallback to the old error message.
+ */
+static void print_data_reloc_error(const struct btrfs_inode *inode, u64 file_off,
+				   const u8 *csum, const u8 *csum_expected,
+				   int mirror_num)
+{
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+	BTRFS_PATH_AUTO_RELEASE(path);
+	struct btrfs_key found_key = { 0 };
+	struct extent_buffer *eb;
+	struct btrfs_extent_item *ei;
+	const u32 csum_size = fs_info->csum_size;
+	u64 logical;
+	u64 flags;
+	u32 item_size;
+	int ret;
+
+	logical = btrfs_get_reloc_bg_bytenr(fs_info);
+
+	if (logical == U64_MAX) {
+		btrfs_warn_rl(fs_info, "has data reloc tree but no running relocation");
+		btrfs_warn_rl(fs_info,
+"csum failed root %lld ino %llu off %llu csum " BTRFS_CSUM_FMT " expected csum " BTRFS_CSUM_FMT " mirror %d",
+			btrfs_root_id(inode->root), btrfs_ino(inode), file_off,
+			BTRFS_CSUM_FMT_VALUE(csum_size, csum),
+			BTRFS_CSUM_FMT_VALUE(csum_size, csum_expected),
+			mirror_num);
+		return;
+	}
+
+	logical += file_off;
+	btrfs_warn_rl(fs_info,
+"csum failed root %lld ino %llu off %llu logical %llu csum " BTRFS_CSUM_FMT " expected csum " BTRFS_CSUM_FMT " mirror %d",
+			btrfs_root_id(inode->root),
+			btrfs_ino(inode), file_off, logical,
+			BTRFS_CSUM_FMT_VALUE(csum_size, csum),
+			BTRFS_CSUM_FMT_VALUE(csum_size, csum_expected),
+			mirror_num);
+
+	ret = extent_from_logical(fs_info, logical, &path, &found_key, &flags);
+	if (ret < 0) {
+		btrfs_err_rl(fs_info, "failed to lookup extent item for logical %llu: %pe",
+			     logical, ERR_PTR(ret));
+		return;
+	}
+	eb = path.nodes[0];
+	ei = btrfs_item_ptr(eb, path.slots[0], struct btrfs_extent_item);
+	item_size = btrfs_item_size(eb, path.slots[0]);
+	if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
+		unsigned long ptr = 0;
+		u64 ref_root;
+		u8 ref_level;
+
+		while (true) {
+			ret = tree_backref_for_extent(&ptr, eb, &found_key, ei,
+						      item_size, &ref_root,
+						      &ref_level);
+			if (ret < 0) {
+				btrfs_warn_rl(fs_info,
+				"failed to resolve tree backref for logical %llu: %d",
+					      logical, ret);
+				break;
+			}
+			if (ret > 0)
+				break;
+
+			btrfs_warn_rl(fs_info,
+"csum error at logical %llu mirror %u: metadata %s (level %d) in tree %llu",
+				logical, mirror_num,
+				(ref_level ? "node" : "leaf"),
+				ref_level, ref_root);
+		}
+	} else {
+		struct btrfs_backref_walk_ctx ctx = { 0 };
+		struct data_reloc_warn reloc_warn = { 0 };
+
+		/*
+		 * Do not hold the path as later iterate_extent_inodes() call
+		 * can be time consuming.
+		 */
+		btrfs_release_path(&path);
+
+		ctx.bytenr = found_key.objectid;
+		ctx.extent_item_pos = logical - found_key.objectid;
+		ctx.fs_info = fs_info;
+
+		reloc_warn.logical = logical;
+		reloc_warn.extent_item_size = found_key.offset;
+		reloc_warn.mirror_num = mirror_num;
+		reloc_warn.fs_info = fs_info;
+
+		iterate_extent_inodes(&ctx, true,
+				      data_reloc_print_warning_inode, &reloc_warn);
+	}
+}
+
+static void __cold btrfs_print_data_csum_error(struct btrfs_inode *inode,
+		u64 logical_start, u8 *csum, u8 *csum_expected, int mirror_num)
+{
+	struct btrfs_root *root = inode->root;
+	const u32 csum_size = root->fs_info->csum_size;
+
+	/* For data reloc tree, it's better to do a backref lookup instead. */
+	if (btrfs_is_data_reloc_root(root))
+		return print_data_reloc_error(inode, logical_start, csum,
+					      csum_expected, mirror_num);
+
+	/* Output without objectid, which is more meaningful */
+	if (btrfs_root_id(root) >= BTRFS_LAST_FREE_OBJECTID) {
+		btrfs_warn_rl(root->fs_info,
+"csum failed root %lld ino %lld off %llu csum " BTRFS_CSUM_FMT " expected csum " BTRFS_CSUM_FMT " mirror %d",
+			btrfs_root_id(root), btrfs_ino(inode),
+			logical_start,
+			BTRFS_CSUM_FMT_VALUE(csum_size, csum),
+			BTRFS_CSUM_FMT_VALUE(csum_size, csum_expected),
+			mirror_num);
+	} else {
+		btrfs_warn_rl(root->fs_info,
+"csum failed root %llu ino %llu off %llu csum " BTRFS_CSUM_FMT " expected csum " BTRFS_CSUM_FMT " mirror %d",
+			btrfs_root_id(root), btrfs_ino(inode),
+			logical_start,
+			BTRFS_CSUM_FMT_VALUE(csum_size, csum),
+			BTRFS_CSUM_FMT_VALUE(csum_size, csum_expected),
+			mirror_num);
+	}
+}
+
+/*
+ * Lock inode i_rwsem based on arguments passed.
+ *
+ * ilock_flags can have the following bit set:
+ *
+ * BTRFS_ILOCK_SHARED - acquire a shared lock on the inode
+ * BTRFS_ILOCK_TRY - try to acquire the lock, if fails on first attempt
+ *		     return -EAGAIN
+ * BTRFS_ILOCK_MMAP - acquire a write lock on the i_mmap_lock
+ */
+int btrfs_inode_lock(struct btrfs_inode *inode, unsigned int ilock_flags)
+{
+	if (ilock_flags & BTRFS_ILOCK_SHARED) {
+		if (ilock_flags & BTRFS_ILOCK_TRY) {
+			if (!inode_trylock_shared(&inode->vfs_inode))
+				return -EAGAIN;
+			else
+				return 0;
+		}
+		inode_lock_shared(&inode->vfs_inode);
+	} else {
+		if (ilock_flags & BTRFS_ILOCK_TRY) {
+			if (!inode_trylock(&inode->vfs_inode))
+				return -EAGAIN;
+			else
+				return 0;
+		}
+		inode_lock(&inode->vfs_inode);
+	}
+	if (ilock_flags & BTRFS_ILOCK_MMAP)
+		down_write(&inode->i_mmap_lock);
+	return 0;
+}
+
+/*
+ * Unlock inode i_rwsem.
+ *
+ * ilock_flags should contain the same bits set as passed to btrfs_inode_lock()
+ * to decide whether the lock acquired is shared or exclusive.
+ */
+void btrfs_inode_unlock(struct btrfs_inode *inode, unsigned int ilock_flags)
+{
+	if (ilock_flags & BTRFS_ILOCK_MMAP)
+		up_write(&inode->i_mmap_lock);
+	if (ilock_flags & BTRFS_ILOCK_SHARED)
+		inode_unlock_shared(&inode->vfs_inode);
+	else
+		inode_unlock(&inode->vfs_inode);
+}
+
+/*
+ * Cleanup all submitted ordered extents in specified range to handle errors
+ * from the btrfs_run_delalloc_range() callback.
+ *
+ * NOTE: caller must ensure that when an error happens, it can not call
+ * extent_clear_unlock_delalloc() to clear both the bits EXTENT_DO_ACCOUNTING
+ * and EXTENT_DELALLOC simultaneously, because that causes the reserved metadata
+ * to be released, which we want to happen only when finishing the ordered
+ * extent (btrfs_finish_ordered_io()).
+ */
+static inline void btrfs_cleanup_ordered_extents(struct btrfs_inode *inode,
+						 u64 offset, u64 bytes)
+{
+	return btrfs_mark_ordered_io_finished(inode, offset, bytes, false);
+}
+
+static int btrfs_dirty_inode(struct btrfs_inode *inode);
+
+static int btrfs_init_inode_security(struct btrfs_trans_handle *trans,
+				     struct btrfs_new_inode_args *args)
+{
+	int ret;
+
+	if (args->default_acl) {
+		ret = __btrfs_set_acl(trans, args->inode, args->default_acl,
+				      ACL_TYPE_DEFAULT);
+		if (ret)
+			return ret;
+	}
+	if (args->acl) {
+		ret = __btrfs_set_acl(trans, args->inode, args->acl, ACL_TYPE_ACCESS);
+		if (ret)
+			return ret;
+	}
+	if (!args->default_acl && !args->acl)
+		cache_no_acl(args->inode);
+	return btrfs_xattr_security_init(trans, args->inode, args->dir,
+					 &args->dentry->d_name);
+}
+
+/*
+ * this does all the hard work for inserting an inline extent into
+ * the btree.  The caller should have done a btrfs_drop_extents so that
+ * no overlapping inline items exist in the btree
+ */
+static int insert_inline_extent(struct btrfs_trans_handle *trans,
+				struct btrfs_path *path,
+				struct btrfs_inode *inode, bool extent_inserted,
+				size_t size, size_t compressed_size,
+				int compress_type,
+				struct folio *compressed_folio,
+				bool update_i_size)
+{
+	struct btrfs_root *root = inode->root;
+	struct extent_buffer *leaf;
+	const u32 sectorsize = trans->fs_info->sectorsize;
+	char *kaddr;
+	unsigned long ptr;
+	struct btrfs_file_extent_item *ei;
+	int ret;
+	size_t cur_size = size;
+	u64 i_size;
+
+	/*
+	 * The decompressed size must still be no larger than a sector.  Under
+	 * heavy race, we can have size == 0 passed in, but that shouldn't be a
+	 * big deal and we can continue the insertion.
+	 */
+	ASSERT(size <= sectorsize);
+
+	/*
+	 * The compressed size also needs to be no larger than a page.
+	 * That's also why we only need one folio as the parameter.
+	 */
+	if (compressed_folio) {
+		ASSERT(compressed_size <= sectorsize);
+		ASSERT(compressed_size <= PAGE_SIZE);
+	} else {
+		ASSERT(compressed_size == 0);
+	}
+
+	if (compressed_size && compressed_folio)
+		cur_size = compressed_size;
+
+	if (!extent_inserted) {
+		struct btrfs_key key;
+		size_t datasize;
+
+		key.objectid = btrfs_ino(inode);
+		key.type = BTRFS_EXTENT_DATA_KEY;
+		key.offset = 0;
+
+		datasize = btrfs_file_extent_calc_inline_size(cur_size);
+		ret = btrfs_insert_empty_item(trans, root, path, &key,
+					      datasize);
+		if (ret)
+			return ret;
+	}
+	leaf = path->nodes[0];
+	ei = btrfs_item_ptr(leaf, path->slots[0],
+			    struct btrfs_file_extent_item);
+	btrfs_set_file_extent_generation(leaf, ei, trans->transid);
+	btrfs_set_file_extent_type(leaf, ei, BTRFS_FILE_EXTENT_INLINE);
+	btrfs_set_file_extent_encryption(leaf, ei, 0);
+	btrfs_set_file_extent_other_encoding(leaf, ei, 0);
+	btrfs_set_file_extent_ram_bytes(leaf, ei, size);
+	ptr = btrfs_file_extent_inline_start(ei);
+
+	if (compress_type != BTRFS_COMPRESS_NONE) {
+		kaddr = kmap_local_folio(compressed_folio, 0);
+		write_extent_buffer(leaf, kaddr, ptr, compressed_size);
+		kunmap_local(kaddr);
+
+		btrfs_set_file_extent_compression(leaf, ei,
+						  compress_type);
+	} else {
+		struct folio *folio;
+
+		folio = filemap_get_folio(inode->vfs_inode.i_mapping, 0);
+		ASSERT(!IS_ERR(folio));
+		btrfs_set_file_extent_compression(leaf, ei, 0);
+		kaddr = kmap_local_folio(folio, 0);
+		write_extent_buffer(leaf, kaddr, ptr, size);
+		kunmap_local(kaddr);
+		folio_put(folio);
+	}
+	btrfs_release_path(path);
+
+	/*
+	 * We align size to sectorsize for inline extents just for simplicity
+	 * sake.
+	 */
+	ret = btrfs_inode_set_file_extent_range(inode, 0,
+					ALIGN(size, root->fs_info->sectorsize));
+	if (ret)
+		return ret;
+
+	/*
+	 * We're an inline extent, so nobody can extend the file past i_size
+	 * without locking a page we already have locked.
+	 *
+	 * We must do any i_size and inode updates before we unlock the pages.
+	 * Otherwise we could end up racing with unlink.
+	 */
+	i_size = i_size_read(&inode->vfs_inode);
+	if (update_i_size && size > i_size) {
+		i_size_write(&inode->vfs_inode, size);
+		i_size = size;
+	}
+	inode->disk_i_size = i_size;
+
+	return 0;
+}
+
+static bool can_cow_file_range_inline(struct btrfs_inode *inode,
+				      u64 offset, u64 size,
+				      size_t compressed_size)
+{
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+	u64 data_len = (compressed_size ?: size);
+
+	/* Inline extents must start at offset 0. */
+	if (offset != 0)
+		return false;
+
+	/*
+	 * Even for bs > ps cases, cow_file_range_inline() can only accept a
+	 * single folio.
+	 *
+	 * This can be problematic and cause access beyond page boundary if a
+	 * page sized folio is passed into that function.
+	 * And encoded write is doing exactly that.
+	 * So here limits the inlined extent size to PAGE_SIZE.
+	 */
+	if (size > PAGE_SIZE || compressed_size > PAGE_SIZE)
+		return false;
+
+	/* Inline extents are limited to sectorsize. */
+	if (size > fs_info->sectorsize)
+		return false;
+
+	/* We do not allow a non-compressed extent to be as large as block size. */
+	if (data_len >= fs_info->sectorsize)
+		return false;
+
+	/* We cannot exceed the maximum inline data size. */
+	if (data_len > BTRFS_MAX_INLINE_DATA_SIZE(fs_info))
+		return false;
+
+	/* We cannot exceed the user specified max_inline size. */
+	if (data_len > fs_info->max_inline)
+		return false;
+
+	/* Inline extents must be the entirety of the file. */
+	if (size < i_size_read(&inode->vfs_inode))
+		return false;
+
+	/* Encrypted file cannot be inlined. */
+	if (IS_ENCRYPTED(&inode->vfs_inode))
+		return false;
+
+	return true;
+}
+
+/*
+ * conditionally insert an inline extent into the file.  This
+ * does the checks required to make sure the data is small enough
+ * to fit as an inline extent.
+ *
+ * If being used directly, you must have already checked we're allowed to cow
+ * the range by getting true from can_cow_file_range_inline().
+ *
+ * Return 0 if the inlined extent is created successfully.
+ * Return <0 for critical error, and should be considered as an writeback error.
+ * Return >0 if can not create an inlined extent (mostly due to lack of meta space).
+ */
+static noinline int __cow_file_range_inline(struct btrfs_inode *inode,
+					    u64 size, size_t compressed_size,
+					    int compress_type,
+					    struct folio *compressed_folio,
+					    bool update_i_size)
+{
+	struct btrfs_drop_extents_args drop_args = { 0 };
+	struct btrfs_root *root = inode->root;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_trans_handle *trans = NULL;
+	u64 data_len = (compressed_size ?: size);
+	int ret;
+	struct btrfs_path *path;
+
+	path = btrfs_alloc_path();
+	if (!path) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	trans = btrfs_join_transaction(root);
+	if (IS_ERR(trans)) {
+		ret = PTR_ERR(trans);
+		trans = NULL;
+		goto out;
+	}
+	trans->block_rsv = &inode->block_rsv;
+
+	drop_args.path = path;
+	drop_args.start = 0;
+	drop_args.end = fs_info->sectorsize;
+	drop_args.drop_cache = true;
+	drop_args.replace_extent = true;
+	drop_args.extent_item_size = btrfs_file_extent_calc_inline_size(data_len);
+	ret = btrfs_drop_extents(trans, root, inode, &drop_args);
+	if (unlikely(ret)) {
+		btrfs_abort_transaction(trans, ret);
+		goto out;
+	}
+
+	ret = insert_inline_extent(trans, path, inode, drop_args.extent_inserted,
+				   size, compressed_size, compress_type,
+				   compressed_folio, update_i_size);
+	if (unlikely(ret && ret != -ENOSPC)) {
+		btrfs_abort_transaction(trans, ret);
+		goto out;
+	} else if (ret == -ENOSPC) {
+		ret = 1;
+		goto out;
+	}
+
+	btrfs_update_inode_bytes(inode, size, drop_args.bytes_found);
+	ret = btrfs_update_inode(trans, inode);
+	if (unlikely(ret && ret != -ENOSPC)) {
+		btrfs_abort_transaction(trans, ret);
+		goto out;
+	} else if (ret == -ENOSPC) {
+		ret = 1;
+		goto out;
+	}
+
+	btrfs_set_inode_full_sync(inode);
+out:
+	/*
+	 * Don't forget to free the reserved space, as for inlined extent
+	 * it won't count as data extent, free them directly here.
+	 * And at reserve time, it's always aligned to sector size, so
+	 * just free one sector here.
+	 *
+	 * If we fallback to non-inline (ret == 1) due to -ENOSPC, then we need
+	 * to keep the data reservation.
+	 */
+	if (ret <= 0)
+		btrfs_qgroup_free_data(inode, NULL, 0, fs_info->sectorsize, NULL);
+	btrfs_free_path(path);
+	if (trans)
+		btrfs_end_transaction(trans);
+	return ret;
+}
+
+struct async_extent {
+	u64 start;
+	u64 ram_size;
+	struct compressed_bio *cb;
+	struct list_head list;
+};
+
+struct async_chunk {
+	struct btrfs_inode *inode;
+	struct folio *locked_folio;
+	u64 start;
+	u64 end;
+	blk_opf_t write_flags;
+	struct list_head extents;
+	struct cgroup_subsys_state *blkcg_css;
+	struct btrfs_work work;
+	struct async_cow *async_cow;
+};
+
+struct async_cow {
+	atomic_t num_chunks;
+	struct async_chunk chunks[];
+};
+
+static int add_async_extent(struct async_chunk *cow, u64 start, u64 ram_size,
+			    struct compressed_bio *cb)
+{
+	struct async_extent *async_extent;
+
+	async_extent = kmalloc_obj(*async_extent, GFP_NOFS);
+	if (!async_extent)
+		return -ENOMEM;
+	ASSERT(ram_size < U32_MAX);
+	async_extent->start = start;
+	async_extent->ram_size = ram_size;
+	async_extent->cb = cb;
+	list_add_tail(&async_extent->list, &cow->extents);
+	return 0;
+}
+
+/*
+ * Check if the inode needs to be submitted to compression, based on mount
+ * options, defragmentation, properties or heuristics.
+ */
+static inline int inode_need_compress(struct btrfs_inode *inode, u64 start,
+				      u64 end, bool check_inline)
+{
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+
+	if (unlikely(!btrfs_inode_can_compress(inode))) {
+		DEBUG_WARN("BTRFS: unexpected compression for ino %llu", btrfs_ino(inode));
+		return 0;
+	}
+
+	/*
+	 * If the delalloc range is only one fs block and can not be inlined,
+	 * do not even bother try compression, as there will be no space saving
+	 * and will always fallback to regular write later.
+	 */
+	if (end + 1 - start <= fs_info->sectorsize &&
+	    (!check_inline || (start > 0 || end + 1 < inode->disk_i_size)))
+		return 0;
+
+	/* Defrag ioctl takes precedence over mount options and properties. */
+	if (inode->defrag_compress == BTRFS_DEFRAG_DONT_COMPRESS)
+		return 0;
+	if (BTRFS_COMPRESS_NONE < inode->defrag_compress &&
+	    inode->defrag_compress < BTRFS_NR_COMPRESS_TYPES)
+		return 1;
+	/* force compress */
+	if (btrfs_test_opt(fs_info, FORCE_COMPRESS))
+		return 1;
+	/* bad compression ratios */
+	if (inode->flags & BTRFS_INODE_NOCOMPRESS)
+		return 0;
+	if (btrfs_test_opt(fs_info, COMPRESS) ||
+	    inode->flags & BTRFS_INODE_COMPRESS ||
+	    inode->prop_compress)
+		return btrfs_compress_heuristic(inode, start, end);
+	return 0;
+}
+
+static inline void inode_should_defrag(struct btrfs_inode *inode,
+		u64 start, u64 end, u64 num_bytes, u32 small_write)
+{
+	/* If this is a small write inside eof, kick off a defrag */
+	if (num_bytes < small_write &&
+	    (start > 0 || end + 1 < inode->disk_i_size))
+		btrfs_add_inode_defrag(inode, small_write);
+}
+
+static int extent_range_clear_dirty_for_io(struct btrfs_inode *inode, u64 start, u64 end)
+{
+	pgoff_t index = start >> PAGE_SHIFT;
+	const pgoff_t end_index = end >> PAGE_SHIFT;
+	struct folio *folio;
+	int ret = 0;
+
+	while (index <= end_index) {
+		folio = filemap_get_folio(inode->vfs_inode.i_mapping, index);
+		if (IS_ERR(folio)) {
+			if (!ret)
+				ret = PTR_ERR(folio);
+			index++;
+			continue;
+		}
+		/*
+		 * We are about to compress the folio, so it must not be mmap
+		 * writeable or we could corrupt the data as we attempt to
+		 * compress it.
+		 */
+		btrfs_check_folio_write_protected(folio);
+		btrfs_folio_clamp_clear_dirty(inode->root->fs_info, folio, start,
+					      end + 1 - start);
+		index = folio_next_index(folio);
+		folio_put(folio);
+	}
+	return ret;
+}
+
+static struct folio *compressed_bio_last_folio(struct compressed_bio *cb)
+{
+	struct bio *bio = &cb->bbio.bio;
+	struct bio_vec *bvec;
+	phys_addr_t paddr;
+
+	/*
+	 * Make sure all folios have the same min_folio_size.
+	 *
+	 * Otherwise we cannot simply use offset_in_offset(folio, bi_size) to
+	 * calculate the end of the last folio.
+	 */
+	if (IS_ENABLED(CONFIG_BTRFS_ASSERT)) {
+		struct btrfs_fs_info *fs_info = cb_to_fs_info(cb);
+		const u32 min_folio_size = btrfs_min_folio_size(fs_info);
+		struct folio_iter fi;
+
+		bio_for_each_folio_all(fi, bio)
+			ASSERT(folio_size(fi.folio) == min_folio_size);
+	}
+
+	/* The bio must not be empty. */
+	ASSERT(bio->bi_vcnt);
+
+	bvec = &bio->bi_io_vec[bio->bi_vcnt - 1];
+	paddr = bvec_phys(bvec) + bvec->bv_len - 1;
+	return page_folio(phys_to_page(paddr));
+}
+
+static void round_up_last_block(struct compressed_bio *cb, u32 blocksize)
+{
+	struct bio *bio = &cb->bbio.bio;
+	struct folio *last_folio = compressed_bio_last_folio(cb);
+	const u32 bio_size = bio->bi_iter.bi_size;
+	const u32 foffset = offset_in_folio(last_folio, bio_size);
+	const u32 padding_len = round_up(foffset, blocksize) - foffset;
+	bool ret;
+
+	if (IS_ALIGNED(bio_size, blocksize))
+		return;
+
+	folio_zero_range(last_folio, foffset, padding_len);
+	ret = bio_add_folio(bio, last_folio, padding_len, foffset);
+	/* The remaining part should be merged thus never fail. */
+	ASSERT(ret);
+}
+
+/*
+ * Work queue call back to started compression on a file and pages.
+ *
+ * This is done inside an ordered work queue, and the compression is spread
+ * across many cpus.  The actual IO submission is step two, and the ordered work
+ * queue takes care of making sure that happens in the same order things were
+ * put onto the queue by writepages and friends.
+ *
+ * If this code finds it can't get good compression, it puts an entry onto the
+ * work queue to write the uncompressed bytes.  This makes sure that both
+ * compressed inodes and uncompressed inodes are written in the same order that
+ * the flusher thread sent them down.
+ */
+static void compress_file_range(struct btrfs_work *work)
+{
+	struct async_chunk *async_chunk =
+		container_of(work, struct async_chunk, work);
+	struct btrfs_inode *inode = async_chunk->inode;
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+	struct compressed_bio *cb = NULL;
+	const u32 blocksize = fs_info->sectorsize;
+	u64 start = async_chunk->start;
+	u64 end = async_chunk->end;
+	u64 actual_end;
+	u64 i_size;
+	u32 cur_len;
+	int ret = 0;
+	unsigned long total_compressed = 0;
+	unsigned long total_in = 0;
+	int compress_type = fs_info->compress_type;
+	int compress_level = fs_info->compress_level;
+
+	if (btrfs_is_shutdown(fs_info))
+		goto cleanup_and_bail_uncompressed;
+
+	inode_should_defrag(inode, start, end, end - start + 1, SZ_16K);
+
+	ret = extent_range_clear_dirty_for_io(inode, start, end);
+
+	/*
+	 * All the folios should have been locked thus no failure.
+	 *
+	 * And even if some folios are missing, btrfs_compress_bio()
+	 * would handle them correctly, so here just do an ASSERT() check for
+	 * early logic errors.
+	 */
+	ASSERT(ret == 0);
+
+	/*
+	 * We need to save i_size before now because it could change in between
+	 * us evaluating the size and assigning it.  This is because we lock and
+	 * unlock the page in truncate and fallocate, and then modify the i_size
+	 * later on.
+	 *
+	 * The barriers are to emulate READ_ONCE, remove that once i_size_read
+	 * does that for us.
+	 */
+	barrier();
+	i_size = i_size_read(&inode->vfs_inode);
+	barrier();
+	actual_end = min_t(u64, i_size, end + 1);
+again:
+	total_in = 0;
+	cur_len = min(end + 1 - start, BTRFS_MAX_UNCOMPRESSED);
+	ret = 0;
+	cb = NULL;
+
+	/*
+	 * we don't want to send crud past the end of i_size through
+	 * compression, that's just a waste of CPU time.  So, if the
+	 * end of the file is before the start of our current
+	 * requested range of bytes, we bail out to the uncompressed
+	 * cleanup code that can deal with all of this.
+	 *
+	 * It isn't really the fastest way to fix things, but this is a
+	 * very uncommon corner.
+	 */
+	if (actual_end <= start)
+		goto cleanup_and_bail_uncompressed;
+
+	/*
+	 * We do compression for mount -o compress and when the inode has not
+	 * been flagged as NOCOMPRESS.  This flag can change at any time if we
+	 * discover bad compression ratios.
+	 */
+	if (!inode_need_compress(inode, start, end, false))
+		goto cleanup_and_bail_uncompressed;
+
+	if (0 < inode->defrag_compress && inode->defrag_compress < BTRFS_NR_COMPRESS_TYPES) {
+		compress_type = inode->defrag_compress;
+		compress_level = inode->defrag_compress_level;
+	} else if (inode->prop_compress) {
+		compress_type = inode->prop_compress;
+	}
+
+	/* Compression level is applied here. */
+	cb = btrfs_compress_bio(inode, start, cur_len, compress_type,
+				 compress_level, async_chunk->write_flags);
+	if (IS_ERR(cb)) {
+		cb = NULL;
+		goto mark_incompressible;
+	}
+
+	total_compressed = cb->bbio.bio.bi_iter.bi_size;
+	total_in = cur_len;
+
+	/*
+	 * We aren't doing an inline extent. Round the compressed size up to a
+	 * block size boundary so the allocator does sane things.
+	 */
+	round_up_last_block(cb, blocksize);
+	total_compressed = cb->bbio.bio.bi_iter.bi_size;
+	ASSERT(IS_ALIGNED(total_compressed, blocksize));
+
+	/*
+	 * One last check to make sure the compression is really a win, compare
+	 * the page count read with the blocks on disk, compression must free at
+	 * least one sector.
+	 */
+	total_in = round_up(total_in, fs_info->sectorsize);
+	if (total_compressed + blocksize > total_in)
+		goto mark_incompressible;
+
+
+	/*
+	 * The async work queues will take care of doing actual allocation on
+	 * disk for these compressed pages, and will submit the bios.
+	 */
+	ret = add_async_extent(async_chunk, start, total_in, cb);
+	BUG_ON(ret);
+	if (start + total_in < end) {
+		start += total_in;
+		cond_resched();
+		goto again;
+	}
+	return;
+
+mark_incompressible:
+	if (!btrfs_test_opt(fs_info, FORCE_COMPRESS) && !inode->prop_compress)
+		inode->flags |= BTRFS_INODE_NOCOMPRESS;
+cleanup_and_bail_uncompressed:
+	ret = add_async_extent(async_chunk, start, end - start + 1, NULL);
+	BUG_ON(ret);
+	if (cb)
+		cleanup_compressed_bio(cb);
+}
+
+static void submit_uncompressed_range(struct btrfs_inode *inode,
+				      struct async_extent *async_extent,
+				      struct folio *locked_folio)
+{
+	u64 start = async_extent->start;
+	u64 end = async_extent->start + async_extent->ram_size - 1;
+	int ret;
+	struct writeback_control wbc = {
+		.sync_mode		= WB_SYNC_ALL,
+		.range_start		= start,
+		.range_end		= end,
+		.no_cgroup_owner	= 1,
+	};
+
+	wbc_attach_fdatawrite_inode(&wbc, &inode->vfs_inode);
+	ret = run_delalloc_cow(inode, locked_folio, start, end,
+			       &wbc, false);
+	wbc_detach_inode(&wbc);
+	if (ret < 0) {
+		if (locked_folio)
+			btrfs_folio_end_lock(inode->root->fs_info, locked_folio,
+					     start, async_extent->ram_size);
+		btrfs_err_rl(inode->root->fs_info,
+			"%s failed, root=%llu inode=%llu start=%llu len=%llu: %pe",
+			     __func__, btrfs_root_id(inode->root),
+			     btrfs_ino(inode), start, async_extent->ram_size,
+			     ERR_PTR(ret));
+	}
+}
+
+static void submit_one_async_extent(struct async_chunk *async_chunk,
+				    struct async_extent *async_extent,
+				    u64 *alloc_hint)
+{
+	struct btrfs_inode *inode = async_chunk->inode;
+	struct extent_io_tree *io_tree = &inode->io_tree;
+	struct btrfs_root *root = inode->root;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_ordered_extent *ordered;
+	struct btrfs_file_extent file_extent;
+	struct btrfs_key ins;
+	struct folio *locked_folio = NULL;
+	struct extent_state *cached = NULL;
+	struct extent_map *em;
+	int ret = 0;
+	u32 compressed_size;
+	u64 start = async_extent->start;
+	u64 end = async_extent->start + async_extent->ram_size - 1;
+
+	if (async_chunk->blkcg_css)
+		kthread_associate_blkcg(async_chunk->blkcg_css);
+
+	/*
+	 * If async_chunk->locked_folio is in the async_extent range, we need to
+	 * handle it.
+	 */
+	if (async_chunk->locked_folio) {
+		u64 locked_folio_start = folio_pos(async_chunk->locked_folio);
+		u64 locked_folio_end = locked_folio_start +
+			folio_size(async_chunk->locked_folio) - 1;
+
+		if (!(start >= locked_folio_end || end <= locked_folio_start))
+			locked_folio = async_chunk->locked_folio;
+	}
+
+	if (!async_extent->cb) {
+		submit_uncompressed_range(inode, async_extent, locked_folio);
+		goto done;
+	}
+
+	compressed_size = async_extent->cb->bbio.bio.bi_iter.bi_size;
+	ret = btrfs_reserve_extent(root, async_extent->ram_size,
+				   compressed_size, compressed_size,
+				   0, *alloc_hint, &ins, true, true);
+	if (ret) {
+		/*
+		 * We can't reserve contiguous space for the compressed size.
+		 * Unlikely, but it's possible that we could have enough
+		 * non-contiguous space for the uncompressed size instead.  So
+		 * fall back to uncompressed.
+		 */
+		submit_uncompressed_range(inode, async_extent, locked_folio);
+		cleanup_compressed_bio(async_extent->cb);
+		async_extent->cb = NULL;
+		goto done;
+	}
+
+	btrfs_lock_extent(io_tree, start, end, &cached);
+
+	/* Here we're doing allocation and writeback of the compressed pages */
+	file_extent.disk_bytenr = ins.objectid;
+	file_extent.disk_num_bytes = ins.offset;
+	file_extent.ram_bytes = async_extent->ram_size;
+	file_extent.num_bytes = async_extent->ram_size;
+	file_extent.offset = 0;
+	file_extent.compression = async_extent->cb->compress_type;
+
+	async_extent->cb->bbio.bio.bi_iter.bi_sector = ins.objectid >> SECTOR_SHIFT;
+
+	em = btrfs_create_io_em(inode, start, &file_extent, BTRFS_ORDERED_COMPRESSED);
+	if (IS_ERR(em)) {
+		ret = PTR_ERR(em);
+		goto out_free_reserve;
+	}
+	btrfs_free_extent_map(em);
+
+	ordered = btrfs_alloc_ordered_extent(inode, start, &file_extent,
+					     1U << BTRFS_ORDERED_COMPRESSED);
+	if (IS_ERR(ordered)) {
+		btrfs_drop_extent_map_range(inode, start, end, false);
+		ret = PTR_ERR(ordered);
+		goto out_free_reserve;
+	}
+	async_extent->cb->bbio.ordered = ordered;
+	btrfs_dec_block_group_reservations(fs_info, ins.objectid);
+
+	/* Clear dirty, set writeback and unlock the pages. */
+	extent_clear_unlock_delalloc(inode, start, end,
+			NULL, &cached, EXTENT_LOCKED | EXTENT_DELALLOC,
+			PAGE_UNLOCK | PAGE_START_WRITEBACK);
+	btrfs_submit_bbio(&async_extent->cb->bbio, 0);
+	async_extent->cb = NULL;
+
+	*alloc_hint = ins.objectid + ins.offset;
+done:
+	if (async_chunk->blkcg_css)
+		kthread_associate_blkcg(NULL);
+	kfree(async_extent);
+	return;
+
+out_free_reserve:
+	btrfs_dec_block_group_reservations(fs_info, ins.objectid);
+	btrfs_free_reserved_extent(fs_info, ins.objectid, ins.offset, true);
+	mapping_set_error(inode->vfs_inode.i_mapping, -EIO);
+	extent_clear_unlock_delalloc(inode, start, end,
+				     NULL, &cached,
+				     EXTENT_LOCKED | EXTENT_DELALLOC |
+				     EXTENT_DELALLOC_NEW |
+				     EXTENT_DEFRAG | EXTENT_CLEAR_META_RESV,
+				     PAGE_UNLOCK | PAGE_START_WRITEBACK |
+				     PAGE_END_WRITEBACK);
+	if (async_extent->cb)
+		cleanup_compressed_bio(async_extent->cb);
+	if (async_chunk->blkcg_css)
+		kthread_associate_blkcg(NULL);
+	btrfs_debug(fs_info,
+"async extent submission failed root=%lld inode=%llu start=%llu len=%llu ret=%d",
+		    btrfs_root_id(root), btrfs_ino(inode), start,
+		    async_extent->ram_size, ret);
+	kfree(async_extent);
+}
+
+u64 btrfs_get_extent_allocation_hint(struct btrfs_inode *inode, u64 start,
+				     u64 num_bytes)
+{
+	struct extent_map_tree *em_tree = &inode->extent_tree;
+	struct extent_map *em;
+	u64 alloc_hint = 0;
+
+	read_lock(&em_tree->lock);
+	em = btrfs_search_extent_mapping(em_tree, start, num_bytes);
+	if (em) {
+		/*
+		 * if block start isn't an actual block number then find the
+		 * first block in this inode and use that as a hint.  If that
+		 * block is also bogus then just don't worry about it.
+		 */
+		if (em->disk_bytenr >= EXTENT_MAP_LAST_BYTE) {
+			btrfs_free_extent_map(em);
+			em = btrfs_search_extent_mapping(em_tree, 0, 0);
+			if (em && em->disk_bytenr < EXTENT_MAP_LAST_BYTE)
+				alloc_hint = btrfs_extent_map_block_start(em);
+			if (em)
+				btrfs_free_extent_map(em);
+		} else {
+			alloc_hint = btrfs_extent_map_block_start(em);
+			btrfs_free_extent_map(em);
+		}
+	}
+	read_unlock(&em_tree->lock);
+
+	return alloc_hint;
+}
+
+/*
+ * Handle COW for one range.
+ *
+ * @ins:		The key representing the allocated range.
+ * @file_offset:	The file offset of the COW range
+ * @num_bytes:		The expected length of the COW range
+ *			The actually allocated length can be smaller than it.
+ * @min_alloc_size:	The minimal extent size.
+ * @alloc_hint:		The hint for the extent allocator.
+ * @ret_alloc_size:	The COW range handles by this function.
+ *
+ * Return 0 if everything is fine and update @ret_alloc_size updated.  The
+ * range is still locked, and caller should unlock the range after everything
+ * is done or for error handling.
+ *
+ * Return <0 for error and @is updated for where the extra cleanup should
+ * happen. The range [file_offset, file_offset + ret_alloc_size) will be
+ * cleaned up by this function.
+ */
+static int cow_one_range(struct btrfs_inode *inode, struct folio *locked_folio,
+			 struct btrfs_key *ins, struct extent_state **cached,
+			 u64 file_offset, u32 num_bytes, u32 min_alloc_size,
+			 u64 alloc_hint, u32 *ret_alloc_size)
+{
+	struct btrfs_root *root = inode->root;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_ordered_extent *ordered;
+	struct btrfs_file_extent file_extent;
+	struct extent_map *em;
+	u32 cur_len = 0;
+	u64 cur_end;
+	int ret;
+
+	ret = btrfs_reserve_extent(root, num_bytes, num_bytes, min_alloc_size,
+				   0, alloc_hint, ins, true, true);
+	if (ret < 0) {
+		*ret_alloc_size = cur_len;
+		return ret;
+	}
+
+	cur_len = ins->offset;
+	cur_end = file_offset + cur_len - 1;
+
+	file_extent.disk_bytenr = ins->objectid;
+	file_extent.disk_num_bytes = ins->offset;
+	file_extent.num_bytes = ins->offset;
+	file_extent.ram_bytes = ins->offset;
+	file_extent.offset = 0;
+	file_extent.compression = BTRFS_COMPRESS_NONE;
+
+	/*
+	 * Locked range will be released either during error clean up (inside
+	 * this function or by the caller for previously successful ranges) or
+	 * after the whole range is finished.
+	 */
+	btrfs_lock_extent(&inode->io_tree, file_offset, cur_end, cached);
+	em = btrfs_create_io_em(inode, file_offset, &file_extent, BTRFS_ORDERED_REGULAR);
+	if (IS_ERR(em)) {
+		ret = PTR_ERR(em);
+		goto free_reserved;
+	}
+	btrfs_free_extent_map(em);
+
+	ordered = btrfs_alloc_ordered_extent(inode, file_offset, &file_extent,
+					     1U << BTRFS_ORDERED_REGULAR);
+	if (IS_ERR(ordered)) {
+		btrfs_drop_extent_map_range(inode, file_offset, cur_end, false);
+		ret = PTR_ERR(ordered);
+		goto free_reserved;
+	}
+
+	if (btrfs_is_data_reloc_root(root)) {
+		ret = btrfs_reloc_clone_csums(ordered);
+
+		/*
+		 * Only drop cache here, and process as normal.
+		 *
+		 * We must not allow extent_clear_unlock_delalloc() at
+		 * free_reserved label to free meta of this ordered extent, as
+		 * its meta should be freed by btrfs_finish_ordered_io().
+		 *
+		 * So we must continue until @start is increased to
+		 * skip current ordered extent.
+		 */
+		if (ret)
+			btrfs_drop_extent_map_range(inode, file_offset,
+						    cur_end, false);
+	}
+	btrfs_put_ordered_extent(ordered);
+	btrfs_dec_block_group_reservations(fs_info, ins->objectid);
+	/*
+	 * Error handling for btrfs_reloc_clone_csums().
+	 *
+	 * Treat the range as finished, thus only clear EXTENT_LOCKED | EXTENT_DELALLOC.
+	 * The accounting will be done by ordered extents.
+	 */
+	if (unlikely(ret < 0)) {
+		btrfs_cleanup_ordered_extents(inode, file_offset, cur_len);
+		extent_clear_unlock_delalloc(inode, file_offset, cur_end, locked_folio, cached,
+					     EXTENT_LOCKED | EXTENT_DELALLOC,
+					     PAGE_UNLOCK | PAGE_START_WRITEBACK |
+					     PAGE_END_WRITEBACK);
+		mapping_set_error(inode->vfs_inode.i_mapping, -EIO);
+	}
+	*ret_alloc_size = cur_len;
+	return ret;
+
+free_reserved:
+	/*
+	 * If we have reserved an extent for the current range and failed to
+	 * create the respective extent map or ordered extent, it means that
+	 * when we reserved the extent we decremented the extent's size from
+	 * the data space_info's bytes_may_use counter and
+	 * incremented the space_info's bytes_reserved counter by the same
+	 * amount.
+	 *
+	 * We must make sure extent_clear_unlock_delalloc() does not try
+	 * to decrement again the data space_info's bytes_may_use counter, which
+	 * will be handled by btrfs_free_reserved_extent().
+	 *
+	 * Therefore we do not pass it the flag EXTENT_CLEAR_DATA_RESV, but only
+	 * EXTENT_CLEAR_META_RESV.
+	 */
+	extent_clear_unlock_delalloc(inode, file_offset, cur_end, locked_folio, cached,
+				     EXTENT_LOCKED | EXTENT_DELALLOC |
+				     EXTENT_DELALLOC_NEW |
+				     EXTENT_DEFRAG | EXTENT_CLEAR_META_RESV,
+				     PAGE_UNLOCK | PAGE_START_WRITEBACK |
+				     PAGE_END_WRITEBACK);
+	btrfs_qgroup_free_data(inode, NULL, file_offset, cur_len, NULL);
+	btrfs_dec_block_group_reservations(fs_info, ins->objectid);
+	btrfs_free_reserved_extent(fs_info, ins->objectid, ins->offset, true);
+	mapping_set_error(inode->vfs_inode.i_mapping, -EIO);
+	*ret_alloc_size = cur_len;
+	/*
+	 * We should not return -EAGAIN where it's a special return code for
+	 * zoned to catch btrfs_reserved_extent().
+	 */
+	ASSERT(ret != -EAGAIN);
+	return ret;
+}
+
+/*
+ * when extent_io.c finds a delayed allocation range in the file,
+ * the call backs end up in this code.  The basic idea is to
+ * allocate extents on disk for the range, and create ordered data structs
+ * in ram to track those extents.
+ *
+ * locked_folio is the folio that writepage had locked already.  We use
+ * it to make sure we don't do extra locks or unlocks.
+ *
+ * When this function fails, it unlocks all folios except @locked_folio.
+ *
+ * When this function succeed and creates a normal extent, the folio locking
+ * status depends on the passed in flags:
+ *
+ * - If COW_FILE_RANGE_KEEP_LOCKED flag is set, all folios are kept locked.
+ * - Else all folios except for @locked_folio are unlocked.
+ *
+ * When a failure happens in the second or later iteration of the
+ * while-loop, the ordered extents created in previous iterations are cleaned up.
+ */
+static noinline int cow_file_range(struct btrfs_inode *inode,
+				   struct folio *locked_folio, u64 start,
+				   u64 end, u64 *done_offset,
+				   unsigned long flags)
+{
+	struct btrfs_root *root = inode->root;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct extent_state *cached = NULL;
+	u64 alloc_hint = 0;
+	u64 orig_start = start;
+	u64 num_bytes;
+	u32 min_alloc_size;
+	u32 blocksize = fs_info->sectorsize;
+	u32 cur_alloc_size = 0;
+	struct btrfs_key ins;
+	unsigned clear_bits;
+	unsigned long page_ops;
+	int ret = 0;
+
+	if (btrfs_is_shutdown(fs_info)) {
+		ret = -EIO;
+		goto out_unlock;
+	}
+
+	if (btrfs_is_free_space_inode(inode)) {
+		ret = -EINVAL;
+		goto out_unlock;
+	}
+
+	num_bytes = ALIGN(end - start + 1, blocksize);
+	num_bytes = max(blocksize,  num_bytes);
+	ASSERT(num_bytes <= btrfs_super_total_bytes(fs_info->super_copy));
+
+	inode_should_defrag(inode, start, end, num_bytes, SZ_64K);
+	alloc_hint = btrfs_get_extent_allocation_hint(inode, start, num_bytes);
+
+	/*
+	 * We're not doing compressed IO, don't unlock the first page (which
+	 * the caller expects to stay locked), don't clear any dirty bits and
+	 * don't set any writeback bits.
+	 *
+	 * Do set the Ordered (Private2) bit so we know this page was properly
+	 * setup for writepage.
+	 */
+	page_ops = ((flags & COW_FILE_RANGE_KEEP_LOCKED) ? 0 : PAGE_UNLOCK);
+
+	/*
+	 * Relocation relies on the relocated extents to have exactly the same
+	 * size as the original extents. Normally writeback for relocation data
+	 * extents follows a NOCOW path because relocation preallocates the
+	 * extents. However, due to an operation such as scrub turning a block
+	 * group to RO mode, it may fallback to COW mode, so we must make sure
+	 * an extent allocated during COW has exactly the requested size and can
+	 * not be split into smaller extents, otherwise relocation breaks and
+	 * fails during the stage where it updates the bytenr of file extent
+	 * items.
+	 */
+	if (btrfs_is_data_reloc_root(root))
+		min_alloc_size = num_bytes;
+	else
+		min_alloc_size = fs_info->sectorsize;
+
+	while (num_bytes > 0) {
+		ret = cow_one_range(inode, locked_folio, &ins, &cached, start,
+				    num_bytes, min_alloc_size, alloc_hint, &cur_alloc_size);
+
+		if (ret == -EAGAIN) {
+			/*
+			 * cow_one_range() only returns -EAGAIN for zoned
+			 * file systems (from btrfs_reserve_extent()), which
+			 * is an indication that there are
+			 * no active zones to allocate from at the moment.
+			 *
+			 * If this is the first loop iteration, wait for at
+			 * least one zone to finish before retrying the
+			 * allocation.  Otherwise ask the caller to write out
+			 * the already allocated blocks before coming back to
+			 * us, or return -ENOSPC if it can't handle retries.
+			 */
+			ASSERT(btrfs_is_zoned(fs_info));
+			if (start == orig_start) {
+				wait_on_bit_io(&inode->root->fs_info->flags,
+					       BTRFS_FS_NEED_ZONE_FINISH,
+					       TASK_UNINTERRUPTIBLE);
+				continue;
+			}
+			if (done_offset) {
+				/*
+				 * Move @end to the end of the processed range,
+				 * and exit the loop to unlock the processed extents.
+				 */
+				end = start - 1;
+				ret = 0;
+				break;
+			}
+			ret = -ENOSPC;
+		}
+		if (ret < 0)
+			goto out_unlock;
+
+		/* We should not allocate an extent larger than requested.*/
+		ASSERT(cur_alloc_size <= num_bytes);
+
+		num_bytes -= cur_alloc_size;
+		alloc_hint = ins.objectid + ins.offset;
+		start += cur_alloc_size;
+		cur_alloc_size = 0;
+	}
+	extent_clear_unlock_delalloc(inode, orig_start, end, locked_folio, &cached,
+				     EXTENT_LOCKED | EXTENT_DELALLOC, page_ops);
+	if (done_offset)
+		*done_offset = end;
+	return ret;
+
+out_unlock:
+	/*
+	 * Now, we have three regions to clean up:
+	 *
+	 * |-------(1)----|---(2)---|-------------(3)----------|
+	 * `- orig_start  `- start  `- start + cur_alloc_size  `- end
+	 *
+	 * We process each region below.
+	 */
+
+	/*
+	 * For the range (1). We have already instantiated the ordered extents
+	 * for this region, thus we need to cleanup those ordered extents.
+	 * EXTENT_DELALLOC_NEW | EXTENT_DEFRAG | EXTENT_CLEAR_META_RESV
+	 * are also handled by the ordered extents cleanup.
+	 *
+	 * So here we only clear EXTENT_LOCKED and EXTENT_DELALLOC flag, and
+	 * finish the writeback of the involved folios, which will be never submitted.
+	 */
+	if (orig_start < start) {
+		clear_bits = EXTENT_LOCKED | EXTENT_DELALLOC;
+		page_ops = PAGE_UNLOCK | PAGE_START_WRITEBACK | PAGE_END_WRITEBACK;
+
+		if (!locked_folio)
+			mapping_set_error(inode->vfs_inode.i_mapping, ret);
+
+		btrfs_cleanup_ordered_extents(inode, orig_start, start - orig_start);
+		extent_clear_unlock_delalloc(inode, orig_start, start - 1,
+					     locked_folio, NULL, clear_bits, page_ops);
+	}
+
+	clear_bits = EXTENT_LOCKED | EXTENT_DELALLOC | EXTENT_DELALLOC_NEW |
+		     EXTENT_DEFRAG | EXTENT_CLEAR_META_RESV;
+	page_ops = PAGE_UNLOCK | PAGE_START_WRITEBACK | PAGE_END_WRITEBACK;
+
+	/*
+	 * For the range (2) the error handling is done by cow_one_range() itself.
+	 * Nothing needs to be done.
+	 *
+	 * For the range (3). We never touched the region. In addition to the
+	 * clear_bits above, we add EXTENT_CLEAR_DATA_RESV to release the data
+	 * space_info's bytes_may_use counter, reserved in
+	 * btrfs_check_data_free_space().
+	 */
+	if (start + cur_alloc_size < end) {
+		clear_bits |= EXTENT_CLEAR_DATA_RESV;
+		extent_clear_unlock_delalloc(inode, start + cur_alloc_size,
+					     end, locked_folio,
+					     &cached, clear_bits, page_ops);
+		btrfs_qgroup_free_data(inode, NULL, start + cur_alloc_size,
+				       end - start - cur_alloc_size + 1, NULL);
+	}
+	btrfs_err(fs_info,
+"%s failed, root=%llu inode=%llu start=%llu len=%llu cur_offset=%llu cur_alloc_size=%u: %pe",
+		  __func__, btrfs_root_id(inode->root),
+		  btrfs_ino(inode), orig_start, end + 1 - orig_start,
+		  start, cur_alloc_size, ERR_PTR(ret));
+	return ret;
+}
+
+/*
+ * Phase two of compressed writeback.  This is the ordered portion of the code,
+ * which only gets called in the order the work was queued.  We walk all the
+ * async extents created by compress_file_range and send them down to the disk.
+ *
+ * If called with @do_free == true then it'll try to finish the work and free
+ * the work struct eventually.
+ */
+static noinline void submit_compressed_extents(struct btrfs_work *work, bool do_free)
+{
+	struct async_chunk *async_chunk = container_of(work, struct async_chunk,
+						     work);
+	struct btrfs_fs_info *fs_info = btrfs_work_owner(work);
+	struct async_extent *async_extent;
+	unsigned long nr_pages;
+	u64 alloc_hint = 0;
+
+	if (do_free) {
+		struct async_cow *async_cow;
+
+		btrfs_add_delayed_iput(async_chunk->inode);
+		if (async_chunk->blkcg_css)
+			css_put(async_chunk->blkcg_css);
+
+		async_cow = async_chunk->async_cow;
+		if (atomic_dec_and_test(&async_cow->num_chunks))
+			kvfree(async_cow);
+		return;
+	}
+
+	nr_pages = (async_chunk->end - async_chunk->start + PAGE_SIZE) >>
+		PAGE_SHIFT;
+
+	while (!list_empty(&async_chunk->extents)) {
+		async_extent = list_first_entry(&async_chunk->extents,
+						struct async_extent, list);
+		list_del(&async_extent->list);
+		submit_one_async_extent(async_chunk, async_extent, &alloc_hint);
+	}
+
+	/* atomic_sub_return implies a barrier */
+	if (atomic_sub_return(nr_pages, &fs_info->async_delalloc_pages) <
+	    5 * SZ_1M)
+		cond_wake_up_nomb(&fs_info->async_submit_wait);
+}
+
+static bool run_delalloc_compressed(struct btrfs_inode *inode,
+				    struct folio *locked_folio, u64 start,
+				    u64 end, struct writeback_control *wbc)
+{
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+	struct cgroup_subsys_state *blkcg_css = wbc_blkcg_css(wbc);
+	struct async_cow *ctx;
+	struct async_chunk *async_chunk;
+	unsigned long nr_pages;
+	u64 num_chunks = DIV_ROUND_UP(end - start, BTRFS_COMPRESSION_CHUNK_SIZE);
+	int i;
+	unsigned nofs_flag;
+	const blk_opf_t write_flags = wbc_to_write_flags(wbc);
+
+	nofs_flag = memalloc_nofs_save();
+	ctx = kvmalloc_flex(*ctx, chunks, num_chunks);
+	memalloc_nofs_restore(nofs_flag);
+	if (!ctx)
+		return false;
+
+	set_bit(BTRFS_INODE_HAS_ASYNC_EXTENT, &inode->runtime_flags);
+
+	async_chunk = ctx->chunks;
+	atomic_set(&ctx->num_chunks, num_chunks);
+
+	for (i = 0; i < num_chunks; i++) {
+		u64 cur_end = min(end, start + BTRFS_COMPRESSION_CHUNK_SIZE - 1);
+
+		/*
+		 * igrab is called higher up in the call chain, take only the
+		 * lightweight reference for the callback lifetime
+		 */
+		ihold(&inode->vfs_inode);
+		async_chunk[i].async_cow = ctx;
+		async_chunk[i].inode = inode;
+		async_chunk[i].start = start;
+		async_chunk[i].end = cur_end;
+		async_chunk[i].write_flags = write_flags;
+		INIT_LIST_HEAD(&async_chunk[i].extents);
+
+		/*
+		 * The locked_folio comes all the way from writepage and its
+		 * the original folio we were actually given.  As we spread
+		 * this large delalloc region across multiple async_chunk
+		 * structs, only the first struct needs a pointer to
+		 * locked_folio.
+		 *
+		 * This way we don't need racey decisions about who is supposed
+		 * to unlock it.
+		 */
+		if (locked_folio) {
+			/*
+			 * Depending on the compressibility, the pages might or
+			 * might not go through async.  We want all of them to
+			 * be accounted against wbc once.  Let's do it here
+			 * before the paths diverge.  wbc accounting is used
+			 * only for foreign writeback detection and doesn't
+			 * need full accuracy.  Just account the whole thing
+			 * against the first page.
+			 */
+			wbc_account_cgroup_owner(wbc, locked_folio,
+						 cur_end - start);
+			async_chunk[i].locked_folio = locked_folio;
+			locked_folio = NULL;
+		} else {
+			async_chunk[i].locked_folio = NULL;
+		}
+
+		if (blkcg_css != blkcg_root_css) {
+			css_get(blkcg_css);
+			async_chunk[i].blkcg_css = blkcg_css;
+			async_chunk[i].write_flags |= REQ_BTRFS_CGROUP_PUNT;
+		} else {
+			async_chunk[i].blkcg_css = NULL;
+		}
+
+		btrfs_init_work(&async_chunk[i].work, compress_file_range,
+				submit_compressed_extents);
+
+		nr_pages = DIV_ROUND_UP(cur_end - start, PAGE_SIZE);
+		atomic_add(nr_pages, &fs_info->async_delalloc_pages);
+
+		btrfs_queue_work(fs_info->delalloc_workers, &async_chunk[i].work);
+
+		start = cur_end + 1;
+	}
+	return true;
+}
+
+/*
+ * Run the delalloc range from start to end, and write back any dirty pages
+ * covered by the range.
+ */
+static noinline int run_delalloc_cow(struct btrfs_inode *inode,
+				     struct folio *locked_folio, u64 start,
+				     u64 end, struct writeback_control *wbc,
+				     bool pages_dirty)
+{
+	u64 done_offset = end;
+	int ret;
+
+	while (start <= end) {
+		ret = cow_file_range(inode, locked_folio, start, end,
+				     &done_offset, COW_FILE_RANGE_KEEP_LOCKED);
+		if (ret)
+			return ret;
+		extent_write_locked_range(&inode->vfs_inode, locked_folio,
+					  start, done_offset, wbc, pages_dirty);
+		start = done_offset + 1;
+	}
+
+	return 1;
+}
+
+static int fallback_to_cow(struct btrfs_inode *inode,
+			   struct folio *locked_folio, const u64 start,
+			   const u64 end)
+{
+	const bool is_space_ino = btrfs_is_free_space_inode(inode);
+	const bool is_reloc_ino = btrfs_is_data_reloc_root(inode->root);
+	const u64 range_bytes = end + 1 - start;
+	struct extent_io_tree *io_tree = &inode->io_tree;
+	struct extent_state *cached_state = NULL;
+	u64 range_start = start;
+	u64 count;
+	int ret;
+
+	/*
+	 * If EXTENT_NORESERVE is set it means that when the buffered write was
+	 * made we had not enough available data space and therefore we did not
+	 * reserve data space for it, since we though we could do NOCOW for the
+	 * respective file range (either there is prealloc extent or the inode
+	 * has the NOCOW bit set).
+	 *
+	 * However when we need to fallback to COW mode (because for example the
+	 * block group for the corresponding extent was turned to RO mode by a
+	 * scrub or relocation) we need to do the following:
+	 *
+	 * 1) We increment the bytes_may_use counter of the data space info.
+	 *    If COW succeeds, it allocates a new data extent and after doing
+	 *    that it decrements the space info's bytes_may_use counter and
+	 *    increments its bytes_reserved counter by the same amount (we do
+	 *    this at btrfs_add_reserved_bytes()). So we need to increment the
+	 *    bytes_may_use counter to compensate (when space is reserved at
+	 *    buffered write time, the bytes_may_use counter is incremented);
+	 *
+	 * 2) We clear the EXTENT_NORESERVE bit from the range. We do this so
+	 *    that if the COW path fails for any reason, it decrements (through
+	 *    extent_clear_unlock_delalloc()) the bytes_may_use counter of the
+	 *    data space info, which we incremented in the step above.
+	 *
+	 * If we need to fallback to cow and the inode corresponds to a free
+	 * space cache inode or an inode of the data relocation tree, we must
+	 * also increment bytes_may_use of the data space_info for the same
+	 * reason. Space caches and relocated data extents always get a prealloc
+	 * extent for them, however scrub or balance may have set the block
+	 * group that contains that extent to RO mode and therefore force COW
+	 * when starting writeback.
+	 */
+	btrfs_lock_extent(io_tree, start, end, &cached_state);
+	count = btrfs_count_range_bits(io_tree, &range_start, end, range_bytes,
+				       EXTENT_NORESERVE, false, NULL);
+	if (count > 0 || is_space_ino || is_reloc_ino) {
+		u64 bytes = count;
+		struct btrfs_fs_info *fs_info = inode->root->fs_info;
+		struct btrfs_space_info *sinfo = fs_info->data_sinfo;
+
+		if (is_space_ino || is_reloc_ino)
+			bytes = range_bytes;
+
+		spin_lock(&sinfo->lock);
+		btrfs_space_info_update_bytes_may_use(sinfo, bytes);
+		spin_unlock(&sinfo->lock);
+
+		if (count > 0)
+			btrfs_clear_extent_bit(io_tree, start, end, EXTENT_NORESERVE,
+					       &cached_state);
+	}
+	btrfs_unlock_extent(io_tree, start, end, &cached_state);
+
+	/*
+	 * Don't try to create inline extents, as a mix of inline extent that
+	 * is written out and unlocked directly and a normal NOCOW extent
+	 * doesn't work.
+	 *
+	 * And here we do not unlock the folio after a successful run.
+	 * The folios will be unlocked after everything is finished, or by error handling.
+	 *
+	 * This is to ensure error handling won't need to clear dirty/ordered flags without
+	 * a locked folio, which can race with writeback.
+	 */
+	ret = cow_file_range(inode, locked_folio, start, end, NULL,
+			     COW_FILE_RANGE_KEEP_LOCKED);
+	ASSERT(ret != 1);
+	return ret;
+}
+
+struct can_nocow_file_extent_args {
+	/* Input fields. */
+
+	/* Start file offset of the range we want to NOCOW. */
+	u64 start;
+	/* End file offset (inclusive) of the range we want to NOCOW. */
+	u64 end;
+	bool writeback_path;
+	/*
+	 * Free the path passed to can_nocow_file_extent() once it's not needed
+	 * anymore.
+	 */
+	bool free_path;
+
+	/*
+	 * Output fields. Only set when can_nocow_file_extent() returns 1.
+	 * The expected file extent for the NOCOW write.
+	 */
+	struct btrfs_file_extent file_extent;
+};
+
+/*
+ * Check if we can NOCOW the file extent that the path points to.
+ * This function may return with the path released, so the caller should check
+ * if path->nodes[0] is NULL or not if it needs to use the path afterwards.
+ *
+ * Returns: < 0 on error
+ *            0 if we can not NOCOW
+ *            1 if we can NOCOW
+ */
+static int can_nocow_file_extent(struct btrfs_path *path,
+				 struct btrfs_key *key,
+				 struct btrfs_inode *inode,
+				 struct can_nocow_file_extent_args *args)
+{
+	const bool is_freespace_inode = btrfs_is_free_space_inode(inode);
+	struct extent_buffer *leaf = path->nodes[0];
+	struct btrfs_root *root = inode->root;
+	struct btrfs_file_extent_item *fi;
+	struct btrfs_root *csum_root;
+	u64 io_start;
+	u64 extent_end;
+	u8 extent_type;
+	int can_nocow = 0;
+	int ret = 0;
+	bool nowait = path->nowait;
+
+	/* If there are pending snapshots for this root, we must do COW. */
+	if (args->writeback_path && !is_freespace_inode &&
+	    atomic_read(&root->snapshot_force_cow))
+		goto out;
+
+	fi = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_file_extent_item);
+	extent_type = btrfs_file_extent_type(leaf, fi);
+
+	if (extent_type == BTRFS_FILE_EXTENT_INLINE)
+		goto out;
+
+	if (!(inode->flags & BTRFS_INODE_NODATACOW) &&
+	    extent_type == BTRFS_FILE_EXTENT_REG)
+		goto out;
+
+	/*
+	 * If the extent was created before the generation where the last snapshot
+	 * for its subvolume was created, then this implies the extent is shared,
+	 * hence we must COW.
+	 */
+	if (btrfs_file_extent_generation(leaf, fi) <=
+	    btrfs_root_last_snapshot(&root->root_item))
+		goto out;
+
+	/* An explicit hole, must COW. */
+	if (btrfs_file_extent_disk_bytenr(leaf, fi) == 0)
+		goto out;
+
+	/* Compressed/encrypted/encoded extents must be COWed. */
+	if (btrfs_file_extent_compression(leaf, fi) ||
+	    btrfs_file_extent_encryption(leaf, fi) ||
+	    btrfs_file_extent_other_encoding(leaf, fi))
+		goto out;
+
+	extent_end = btrfs_file_extent_end(path);
+
+	args->file_extent.disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
+	args->file_extent.disk_num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
+	args->file_extent.ram_bytes = btrfs_file_extent_ram_bytes(leaf, fi);
+	args->file_extent.offset = btrfs_file_extent_offset(leaf, fi);
+	args->file_extent.compression = btrfs_file_extent_compression(leaf, fi);
+
+	/*
+	 * The following checks can be expensive, as they need to take other
+	 * locks and do btree or rbtree searches, so release the path to avoid
+	 * blocking other tasks for too long.
+	 */
+	btrfs_release_path(path);
+
+	ret = btrfs_cross_ref_exist(inode, key->offset - args->file_extent.offset,
+				    args->file_extent.disk_bytenr, path);
+	WARN_ON_ONCE(ret > 0 && is_freespace_inode);
+	if (ret != 0)
+		goto out;
+
+	if (args->free_path) {
+		/*
+		 * We don't need the path anymore, plus through the
+		 * btrfs_lookup_csums_list() call below we will end up allocating
+		 * another path. So free the path to avoid unnecessary extra
+		 * memory usage.
+		 */
+		btrfs_free_path(path);
+		path = NULL;
+	}
+
+	args->file_extent.num_bytes = min(args->end + 1, extent_end) - args->start;
+	args->file_extent.offset += args->start - key->offset;
+	io_start = args->file_extent.disk_bytenr + args->file_extent.offset;
+
+	/*
+	 * Force COW if csums exist in the range. This ensures that csums for a
+	 * given extent are either valid or do not exist.
+	 */
+
+	csum_root = btrfs_csum_root(root->fs_info, io_start);
+	if (unlikely(!csum_root)) {
+		btrfs_err(root->fs_info,
+			  "missing csum root for extent at bytenr %llu", io_start);
+		ret = -EUCLEAN;
+		goto out;
+	}
+
+	ret = btrfs_lookup_csums_list(csum_root, io_start,
+				      io_start + args->file_extent.num_bytes - 1,
+				      NULL, nowait);
+	WARN_ON_ONCE(ret > 0 && is_freespace_inode);
+	if (ret != 0)
+		goto out;
+
+	can_nocow = 1;
+ out:
+	if (args->free_path && path)
+		btrfs_free_path(path);
+
+	return ret < 0 ? ret : can_nocow;
+}
+
+static int nocow_one_range(struct btrfs_inode *inode, struct folio *locked_folio,
+			   struct extent_state **cached,
+			   struct can_nocow_file_extent_args *nocow_args,
+			   u64 file_pos, bool is_prealloc)
+{
+	struct btrfs_ordered_extent *ordered;
+	const u64 len = nocow_args->file_extent.num_bytes;
+	const u64 end = file_pos + len - 1;
+	int ret = 0;
+
+	btrfs_lock_extent(&inode->io_tree, file_pos, end, cached);
+
+	if (is_prealloc) {
+		struct extent_map *em;
+
+		em = btrfs_create_io_em(inode, file_pos, &nocow_args->file_extent,
+					BTRFS_ORDERED_PREALLOC);
+		if (IS_ERR(em)) {
+			ret = PTR_ERR(em);
+			goto error;
+		}
+		btrfs_free_extent_map(em);
+	}
+
+	ordered = btrfs_alloc_ordered_extent(inode, file_pos, &nocow_args->file_extent,
+					     is_prealloc
+					     ? (1U << BTRFS_ORDERED_PREALLOC)
+					     : (1U << BTRFS_ORDERED_NOCOW));
+	if (IS_ERR(ordered)) {
+		if (is_prealloc)
+			btrfs_drop_extent_map_range(inode, file_pos, end, false);
+		ret = PTR_ERR(ordered);
+		goto error;
+	}
+
+	if (btrfs_is_data_reloc_root(inode->root))
+		/*
+		 * Errors are handled later, as we must prevent
+		 * extent_clear_unlock_delalloc() in error handler from freeing
+		 * metadata of the created ordered extent.
+		 */
+		ret = btrfs_reloc_clone_csums(ordered);
+	btrfs_put_ordered_extent(ordered);
+
+	if (ret < 0)
+		goto error;
+	extent_clear_unlock_delalloc(inode, file_pos, end, locked_folio, cached,
+				     EXTENT_LOCKED | EXTENT_DELALLOC |
+				     EXTENT_CLEAR_DATA_RESV, 0);
+	return ret;
+
+error:
+	btrfs_cleanup_ordered_extents(inode, file_pos, len);
+	extent_clear_unlock_delalloc(inode, file_pos, end, locked_folio, cached,
+				     EXTENT_LOCKED | EXTENT_DELALLOC |
+				     EXTENT_CLEAR_DATA_RESV,
+				     PAGE_UNLOCK | PAGE_START_WRITEBACK |
+				     PAGE_END_WRITEBACK);
+	btrfs_err(inode->root->fs_info,
+		  "%s failed, root=%lld inode=%llu start=%llu len=%llu: %pe",
+		  __func__, btrfs_root_id(inode->root), btrfs_ino(inode),
+		  file_pos, len, ERR_PTR(ret));
+	return ret;
+}
+
+/*
+ * When nocow writeback calls back.  This checks for snapshots or COW copies
+ * of the extents that exist in the file, and COWs the file as required.
+ *
+ * If no cow copies or snapshots exist, we write directly to the existing
+ * blocks on disk
+ */
+static noinline int run_delalloc_nocow(struct btrfs_inode *inode,
+				       struct folio *locked_folio,
+				       const u64 start, const u64 end)
+{
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+	struct btrfs_root *root = inode->root;
+	struct btrfs_path *path = NULL;
+	u64 cow_start = (u64)-1;
+	/*
+	 * If not 0, represents the inclusive end of the last fallback_to_cow()
+	 * range. Only for error handling.
+	 *
+	 * The same for nocow_end, it's to avoid double cleaning up the range
+	 * already cleaned by nocow_one_range().
+	 */
+	u64 cow_end = 0;
+	u64 nocow_end = 0;
+	u64 cur_offset = start;
+	int ret;
+	bool check_prev = true;
+	u64 ino = btrfs_ino(inode);
+	struct can_nocow_file_extent_args nocow_args = { 0 };
+	/* The range that has ordered extent(s). */
+	u64 oe_cleanup_start;
+	u64 oe_cleanup_len = 0;
+	/* The range that is untouched. */
+	u64 untouched_start;
+	u64 untouched_len = 0;
+
+	/*
+	 * Normally on a zoned device we're only doing COW writes, but in case
+	 * of relocation on a zoned filesystem serializes I/O so that we're only
+	 * writing sequentially and can end up here as well.
+	 */
+	ASSERT(!btrfs_is_zoned(fs_info) || btrfs_is_data_reloc_root(root));
+
+	if (btrfs_is_shutdown(fs_info)) {
+		ret = -EIO;
+		goto error;
+	}
+	path = btrfs_alloc_path();
+	if (!path) {
+		ret = -ENOMEM;
+		goto error;
+	}
+
+	nocow_args.end = end;
+	nocow_args.writeback_path = true;
+
+	while (cur_offset <= end) {
+		struct btrfs_block_group *nocow_bg = NULL;
+		struct btrfs_key found_key;
+		struct btrfs_file_extent_item *fi;
+		struct extent_buffer *leaf;
+		struct extent_state *cached_state = NULL;
+		u64 extent_end;
+		int extent_type;
+
+		ret = btrfs_lookup_file_extent(NULL, root, path, ino,
+					       cur_offset, 0);
+		if (ret < 0)
+			goto error;
+
+		/*
+		 * If there is no extent for our range when doing the initial
+		 * search, then go back to the previous slot as it will be the
+		 * one containing the search offset
+		 */
+		if (ret > 0 && path->slots[0] > 0 && check_prev) {
+			leaf = path->nodes[0];
+			btrfs_item_key_to_cpu(leaf, &found_key,
+					      path->slots[0] - 1);
+			if (found_key.objectid == ino &&
+			    found_key.type == BTRFS_EXTENT_DATA_KEY)
+				path->slots[0]--;
+		}
+		check_prev = false;
+next_slot:
+		/* Go to next leaf if we have exhausted the current one */
+		leaf = path->nodes[0];
+		if (path->slots[0] >= btrfs_header_nritems(leaf)) {
+			ret = btrfs_next_leaf(root, path);
+			if (ret < 0)
+				goto error;
+			if (ret > 0)
+				break;
+			leaf = path->nodes[0];
+		}
+
+		btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
+
+		/* Didn't find anything for our INO */
+		if (found_key.objectid > ino)
+			break;
+		/*
+		 * Keep searching until we find an EXTENT_ITEM or there are no
+		 * more extents for this inode
+		 */
+		if (WARN_ON_ONCE(found_key.objectid < ino) ||
+		    found_key.type < BTRFS_EXTENT_DATA_KEY) {
+			path->slots[0]++;
+			goto next_slot;
+		}
+
+		/* Found key is not EXTENT_DATA_KEY or starts after req range */
+		if (found_key.type > BTRFS_EXTENT_DATA_KEY ||
+		    found_key.offset > end)
+			break;
+
+		/*
+		 * If the found extent starts after requested offset, then
+		 * adjust cur_offset to be right before this extent begins.
+		 */
+		if (found_key.offset > cur_offset) {
+			if (cow_start == (u64)-1)
+				cow_start = cur_offset;
+			cur_offset = found_key.offset;
+			goto next_slot;
+		}
+
+		/*
+		 * Found extent which begins before our range and potentially
+		 * intersect it
+		 */
+		fi = btrfs_item_ptr(leaf, path->slots[0],
+				    struct btrfs_file_extent_item);
+		extent_type = btrfs_file_extent_type(leaf, fi);
+		/* If this is triggered then we have a memory corruption. */
+		ASSERT(extent_type < BTRFS_NR_FILE_EXTENT_TYPES);
+		if (WARN_ON(extent_type >= BTRFS_NR_FILE_EXTENT_TYPES)) {
+			ret = -EUCLEAN;
+			goto error;
+		}
+		extent_end = btrfs_file_extent_end(path);
+
+		/*
+		 * If the extent we got ends before our current offset, skip to
+		 * the next extent.
+		 */
+		if (extent_end <= cur_offset) {
+			path->slots[0]++;
+			goto next_slot;
+		}
+
+		nocow_args.start = cur_offset;
+		ret = can_nocow_file_extent(path, &found_key, inode, &nocow_args);
+		if (ret < 0)
+			goto error;
+		if (ret == 0)
+			goto must_cow;
+
+		ret = 0;
+		nocow_bg = btrfs_inc_nocow_writers(fs_info,
+				nocow_args.file_extent.disk_bytenr +
+				nocow_args.file_extent.offset);
+		if (!nocow_bg) {
+must_cow:
+			/*
+			 * If we can't perform NOCOW writeback for the range,
+			 * then record the beginning of the range that needs to
+			 * be COWed.  It will be written out before the next
+			 * NOCOW range if we find one, or when exiting this
+			 * loop.
+			 */
+			if (cow_start == (u64)-1)
+				cow_start = cur_offset;
+			cur_offset = extent_end;
+			if (cur_offset > end)
+				break;
+			if (!path->nodes[0])
+				continue;
+			path->slots[0]++;
+			goto next_slot;
+		}
+
+		/*
+		 * COW range from cow_start to found_key.offset - 1. As the key
+		 * will contain the beginning of the first extent that can be
+		 * NOCOW, following one which needs to be COW'ed
+		 */
+		if (cow_start != (u64)-1) {
+			ret = fallback_to_cow(inode, locked_folio, cow_start,
+					      found_key.offset - 1);
+			if (ret) {
+				cow_end = found_key.offset - 1;
+				btrfs_dec_nocow_writers(nocow_bg);
+				goto error;
+			}
+			cow_start = (u64)-1;
+		}
+
+		ret = nocow_one_range(inode, locked_folio, &cached_state,
+				      &nocow_args, cur_offset,
+				      extent_type == BTRFS_FILE_EXTENT_PREALLOC);
+		btrfs_dec_nocow_writers(nocow_bg);
+		if (ret < 0) {
+			nocow_end = cur_offset + nocow_args.file_extent.num_bytes - 1;
+			goto error;
+		}
+		cur_offset = extent_end;
+	}
+	btrfs_release_path(path);
+
+	if (cur_offset <= end && cow_start == (u64)-1)
+		cow_start = cur_offset;
+
+	if (cow_start != (u64)-1) {
+		ret = fallback_to_cow(inode, locked_folio, cow_start, end);
+		if (ret) {
+			cow_end = end;
+			goto error;
+		}
+		cow_start = (u64)-1;
+	}
+
+	/*
+	 * Everything is finished without an error, can unlock the folios now.
+	 *
+	 * No need to touch the io tree range nor set folio ordered flag, as
+	 * fallback_to_cow() and nocow_one_range() have already handled them.
+	 */
+	extent_clear_unlock_delalloc(inode, start, end, locked_folio, NULL, 0, PAGE_UNLOCK);
+
+	btrfs_free_path(path);
+	return 0;
+
+error:
+	if (cow_start == (u64)-1) {
+		/*
+		 * case a)
+		 *    start           cur_offset               end
+		 *    |   OE cleanup  |       Untouched        |
+		 *
+		 * We finished a fallback_to_cow() or nocow_one_range() call,
+		 * but failed to check the next range.
+		 *
+		 * or
+		 *    start           cur_offset   nocow_end   end
+		 *    |   OE cleanup  |   Skip     | Untouched |
+		 *
+		 * nocow_one_range() failed, the range [cur_offset, nocow_end] is
+		 * already cleaned up.
+		 */
+		oe_cleanup_start = start;
+		oe_cleanup_len = cur_offset - start;
+		if (nocow_end)
+			untouched_start = nocow_end + 1;
+		else
+			untouched_start = cur_offset;
+		untouched_len = end + 1 - untouched_start;
+	} else if (cow_start != (u64)-1 && cow_end == 0) {
+		/*
+		 * case b)
+		 *    start        cow_start    cur_offset   end
+		 *    | OE cleanup |        Untouched        |
+		 *
+		 * We got a range that needs COW, but before we hit the next NOCOW range,
+		 * thus [cow_start, cur_offset) doesn't yet have any OE.
+		 */
+		oe_cleanup_start = start;
+		oe_cleanup_len = cow_start - start;
+		untouched_start = cow_start;
+		untouched_len = end + 1 - untouched_start;
+	} else {
+		/*
+		 * case c)
+		 *    start        cow_start    cow_end      end
+		 *    | OE cleanup |   Skip     |  Untouched |
+		 *
+		 * fallback_to_cow() failed, and fallback_to_cow() will do the
+		 * cleanup for its range, we shouldn't touch the range
+		 * [cow_start, cow_end].
+		 */
+		ASSERT(cow_start != (u64)-1 && cow_end != 0);
+		oe_cleanup_start = start;
+		oe_cleanup_len = cow_start - start;
+		untouched_start = cow_end + 1;
+		untouched_len = end + 1 - untouched_start;
+	}
+
+	if (oe_cleanup_len) {
+		const u64 oe_cleanup_end = oe_cleanup_start + oe_cleanup_len - 1;
+		btrfs_cleanup_ordered_extents(inode, oe_cleanup_start, oe_cleanup_len);
+		extent_clear_unlock_delalloc(inode, oe_cleanup_start, oe_cleanup_end,
+					     locked_folio, NULL,
+					     EXTENT_LOCKED | EXTENT_DELALLOC,
+					     PAGE_UNLOCK | PAGE_START_WRITEBACK |
+					     PAGE_END_WRITEBACK);
+	}
+
+	if (untouched_len) {
+		struct extent_state *cached = NULL;
+		const u64 untouched_end = untouched_start + untouched_len - 1;
+
+		/*
+		 * We need to lock the extent here because we're clearing DELALLOC and
+		 * we're not locked at this point.
+		 */
+		btrfs_lock_extent(&inode->io_tree, untouched_start, untouched_end, &cached);
+		extent_clear_unlock_delalloc(inode, untouched_start, untouched_end,
+					     locked_folio, &cached,
+					     EXTENT_LOCKED | EXTENT_DELALLOC |
+					     EXTENT_DEFRAG |
+					     EXTENT_DO_ACCOUNTING, PAGE_UNLOCK |
+					     PAGE_START_WRITEBACK |
+					     PAGE_END_WRITEBACK);
+		btrfs_qgroup_free_data(inode, NULL, untouched_start, untouched_len, NULL);
+	}
+	btrfs_free_path(path);
+	btrfs_err(fs_info,
+"%s failed, root=%llu inode=%llu start=%llu len=%llu cur_offset=%llu oe_cleanup=%llu oe_cleanup_len=%llu untouched_start=%llu untouched_len=%llu: %pe",
+		  __func__, btrfs_root_id(inode->root), btrfs_ino(inode),
+		  start, end + 1 - start, cur_offset, oe_cleanup_start, oe_cleanup_len,
+		  untouched_start, untouched_len, ERR_PTR(ret));
+	return ret;
+}
+
+static bool should_nocow(struct btrfs_inode *inode, u64 start, u64 end)
+{
+	if (inode->flags & (BTRFS_INODE_NODATACOW | BTRFS_INODE_PREALLOC)) {
+		if (data_race(inode->defrag_bytes) &&
+		    btrfs_test_range_bit_exists(&inode->io_tree, start, end, EXTENT_DEFRAG))
+			return false;
+		return true;
+	}
+	return false;
+}
+
+/*
+ * Return 0 if an inlined extent is created successfully.
+ * Return <0 if critical error happened.
+ * Return >0 if an inline extent can not be created.
+ */
+static int run_delalloc_inline(struct btrfs_inode *inode, struct folio *locked_folio)
+{
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+	struct compressed_bio *cb = NULL;
+	struct extent_state *cached = NULL;
+	const u64 i_size = i_size_read(&inode->vfs_inode);
+	const u32 blocksize = fs_info->sectorsize;
+	int compress_type = fs_info->compress_type;
+	int compress_level = fs_info->compress_level;
+	u32 compressed_size = 0;
+	int ret;
+
+	ASSERT(folio_pos(locked_folio) == 0);
+	/*
+	 * If an mmap writer could modify the folio while we copy it into an
+	 * inline extent we might see only part of their modification then
+	 * wrongly mark it clean again after copying, losing that write. So the
+	 * folio must be write protected here.
+	 */
+	btrfs_check_folio_write_protected(locked_folio);
+
+	if (btrfs_inode_can_compress(inode) &&
+	    inode_need_compress(inode, 0, blocksize, true)) {
+		if (inode->defrag_compress > 0 &&
+		    inode->defrag_compress < BTRFS_NR_COMPRESS_TYPES) {
+			compress_type = inode->defrag_compress;
+			compress_level = inode->defrag_compress_level;
+		} else if (inode->prop_compress) {
+			compress_type = inode->prop_compress;
+		}
+		cb = btrfs_compress_bio(inode, 0, blocksize, compress_type, compress_level, 0);
+		if (IS_ERR(cb)) {
+			cb = NULL;
+			/* Just fall back to non-compressed case. */
+		} else {
+			compressed_size = cb->bbio.bio.bi_iter.bi_size;
+		}
+	}
+	if (!can_cow_file_range_inline(inode, 0, i_size, compressed_size)) {
+		if (cb)
+			cleanup_compressed_bio(cb);
+		return 1;
+	}
+
+	btrfs_lock_extent(&inode->io_tree, 0, blocksize - 1, &cached);
+	if (cb) {
+		ret = __cow_file_range_inline(inode, i_size, compressed_size, compress_type,
+					      bio_first_folio_all(&cb->bbio.bio), false);
+		cleanup_compressed_bio(cb);
+		cb = NULL;
+	} else {
+		ret = __cow_file_range_inline(inode, i_size, 0, BTRFS_COMPRESS_NONE,
+					      NULL, false);
+	}
+	/*
+	 * We failed to insert inline extent due to lack of meta space.
+	 * Just unlock the extent io range and fallback to regular COW/NOCOW path.
+	 */
+	if (ret > 0) {
+		btrfs_unlock_extent(&inode->io_tree, 0, blocksize - 1, &cached);
+		return ret;
+	}
+
+	/*
+	 * In the successful case (ret == 0 here), btrfs_run_delalloc_range()
+	 * will return 1.
+	 *
+	 * Quite a bit further up the callstack in extent_writepage(), ret == 1
+	 * is treated as a short circuited success and does not unlock the folio,
+	 * so we must do it here.
+	 *
+	 * For failure case, the @locked_folio does get unlocked by
+	 * btrfs_folio_end_lock_bitmap(), so we must *not* unlock it here.
+	 *
+	 * So if ret == 0, we let extent_clear_unlock_delalloc() to unlock the
+	 * folio by passing NULL as @locked_folio.
+	 * Otherwise pass @locked_folio as usual.
+	 */
+	if (ret == 0)
+		locked_folio = NULL;
+	extent_clear_unlock_delalloc(inode, 0, blocksize - 1, locked_folio, &cached,
+				     EXTENT_DELALLOC | EXTENT_DELALLOC_NEW | EXTENT_DEFRAG |
+				     EXTENT_DO_ACCOUNTING | EXTENT_LOCKED,
+				     PAGE_UNLOCK | PAGE_START_WRITEBACK | PAGE_END_WRITEBACK);
+	return ret;
+}
+
+/*
+ * Function to process delayed allocation (create CoW) for ranges which are
+ * being touched for the first time.
+ */
+int btrfs_run_delalloc_range(struct btrfs_inode *inode, struct folio *locked_folio,
+			     u64 start, u64 end, struct writeback_control *wbc)
+{
+	const bool zoned = btrfs_is_zoned(inode->root->fs_info);
+
+	/*
+	 * The range must cover part of the @locked_folio, or a return of 1
+	 * can confuse the caller.
+	 */
+	ASSERT(!(end <= folio_pos(locked_folio) ||
+		 start >= folio_next_pos(locked_folio)));
+
+	if (start == 0 && end + 1 <= inode->root->fs_info->sectorsize &&
+	    end + 1 >= inode->disk_i_size) {
+		int ret;
+
+		ret = run_delalloc_inline(inode, locked_folio);
+		if (ret < 0)
+			return ret;
+		if (ret == 0)
+			return 1;
+		/*
+		 * Continue regular handling if we can not create an
+		 * inlined extent.
+		 */
+	}
+
+	if (should_nocow(inode, start, end))
+		return run_delalloc_nocow(inode, locked_folio, start, end);
+
+	if (btrfs_inode_can_compress(inode) &&
+	    inode_need_compress(inode, start, end, false) &&
+	    run_delalloc_compressed(inode, locked_folio, start, end, wbc))
+		return 1;
+
+	if (zoned)
+		return run_delalloc_cow(inode, locked_folio, start, end, wbc, true);
+	else
+		return cow_file_range(inode, locked_folio, start, end, NULL, 0);
+}
+
+void btrfs_split_delalloc_extent(struct btrfs_inode *inode,
+				 struct extent_state *orig, u64 split)
+{
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+	u64 size;
+
+	lockdep_assert_held(&inode->io_tree.lock);
+
+	/* not delalloc, ignore it */
+	if (!(orig->state & EXTENT_DELALLOC))
+		return;
+
+	size = orig->end - orig->start + 1;
+	if (size > fs_info->max_extent_size) {
+		u32 num_extents;
+		u64 new_size;
+
+		/*
+		 * See the explanation in btrfs_merge_delalloc_extent, the same
+		 * applies here, just in reverse.
+		 */
+		new_size = orig->end - split + 1;
+		num_extents = count_max_extents(fs_info, new_size);
+		new_size = split - orig->start;
+		num_extents += count_max_extents(fs_info, new_size);
+		if (count_max_extents(fs_info, size) >= num_extents)
+			return;
+	}
+
+	spin_lock(&inode->lock);
+	btrfs_mod_outstanding_extents(inode, 1);
+	spin_unlock(&inode->lock);
+}
+
+/*
+ * Handle merged delayed allocation extents so we can keep track of new extents
+ * that are just merged onto old extents, such as when we are doing sequential
+ * writes, so we can properly account for the metadata space we'll need.
+ */
+void btrfs_merge_delalloc_extent(struct btrfs_inode *inode, struct extent_state *new,
+				 struct extent_state *other)
+{
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+	u64 new_size, old_size;
+	u32 num_extents;
+
+	lockdep_assert_held(&inode->io_tree.lock);
+
+	/* not delalloc, ignore it */
+	if (!(other->state & EXTENT_DELALLOC))
+		return;
+
+	if (new->start > other->start)
+		new_size = new->end - other->start + 1;
+	else
+		new_size = other->end - new->start + 1;
+
+	/* we're not bigger than the max, unreserve the space and go */
+	if (new_size <= fs_info->max_extent_size) {
+		spin_lock(&inode->lock);
+		btrfs_mod_outstanding_extents(inode, -1);
+		spin_unlock(&inode->lock);
+		return;
+	}
+
+	/*
+	 * We have to add up either side to figure out how many extents were
+	 * accounted for before we merged into one big extent.  If the number of
+	 * extents we accounted for is <= the amount we need for the new range
+	 * then we can return, otherwise drop.  Think of it like this
+	 *
+	 * [ 4k][MAX_SIZE]
+	 *
+	 * So we've grown the extent by a MAX_SIZE extent, this would mean we
+	 * need 2 outstanding extents, on one side we have 1 and the other side
+	 * we have 1 so they are == and we can return.  But in this case
+	 *
+	 * [MAX_SIZE+4k][MAX_SIZE+4k]
+	 *
+	 * Each range on their own accounts for 2 extents, but merged together
+	 * they are only 3 extents worth of accounting, so we need to drop in
+	 * this case.
+	 */
+	old_size = other->end - other->start + 1;
+	num_extents = count_max_extents(fs_info, old_size);
+	old_size = new->end - new->start + 1;
+	num_extents += count_max_extents(fs_info, old_size);
+	if (count_max_extents(fs_info, new_size) >= num_extents)
+		return;
+
+	spin_lock(&inode->lock);
+	btrfs_mod_outstanding_extents(inode, -1);
+	spin_unlock(&inode->lock);
+}
+
+static void btrfs_add_delalloc_inode(struct btrfs_inode *inode)
+{
+	struct btrfs_root *root = inode->root;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+
+	spin_lock(&root->delalloc_lock);
+	ASSERT(list_empty(&inode->delalloc_inodes));
+	list_add_tail(&inode->delalloc_inodes, &root->delalloc_inodes);
+	root->nr_delalloc_inodes++;
+	if (root->nr_delalloc_inodes == 1) {
+		spin_lock(&fs_info->delalloc_root_lock);
+		ASSERT(list_empty(&root->delalloc_root));
+		list_add_tail(&root->delalloc_root, &fs_info->delalloc_roots);
+		spin_unlock(&fs_info->delalloc_root_lock);
+	}
+	spin_unlock(&root->delalloc_lock);
+}
+
+void btrfs_del_delalloc_inode(struct btrfs_inode *inode)
+{
+	struct btrfs_root *root = inode->root;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+
+	lockdep_assert_held(&root->delalloc_lock);
+
+	/*
+	 * We may be called after the inode was already deleted from the list,
+	 * namely in the transaction abort path btrfs_destroy_delalloc_inodes(),
+	 * and then later through btrfs_clear_delalloc_extent() while the inode
+	 * still has ->delalloc_bytes > 0.
+	 */
+	if (!list_empty(&inode->delalloc_inodes)) {
+		list_del_init(&inode->delalloc_inodes);
+		root->nr_delalloc_inodes--;
+		if (!root->nr_delalloc_inodes) {
+			ASSERT(list_empty(&root->delalloc_inodes));
+			spin_lock(&fs_info->delalloc_root_lock);
+			ASSERT(!list_empty(&root->delalloc_root));
+			list_del_init(&root->delalloc_root);
+			spin_unlock(&fs_info->delalloc_root_lock);
+		}
+	}
+}
+
+/*
+ * Properly track delayed allocation bytes in the inode and to maintain the
+ * list of inodes that have pending delalloc work to be done.
+ */
+void btrfs_set_delalloc_extent(struct btrfs_inode *inode, struct extent_state *state,
+			       u32 bits)
+{
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+
+	lockdep_assert_held(&inode->io_tree.lock);
+
+	WARN_ON((bits & EXTENT_DEFRAG) && !(bits & EXTENT_DELALLOC));
+	/*
+	 * set_bit and clear bit hooks normally require _irqsave/restore
+	 * but in this case, we are only testing for the DELALLOC
+	 * bit, which is only set or cleared with irqs on
+	 */
+	if (!(state->state & EXTENT_DELALLOC) && (bits & EXTENT_DELALLOC)) {
+		u64 len = state->end + 1 - state->start;
+		u64 prev_delalloc_bytes;
+		u32 num_extents = count_max_extents(fs_info, len);
+
+		spin_lock(&inode->lock);
+		btrfs_mod_outstanding_extents(inode, num_extents);
+		spin_unlock(&inode->lock);
+
+		/* For sanity tests */
+		if (btrfs_is_testing(fs_info))
+			return;
+
+		percpu_counter_add_batch(&fs_info->delalloc_bytes, len,
+					 fs_info->delalloc_batch);
+		spin_lock(&inode->lock);
+		prev_delalloc_bytes = inode->delalloc_bytes;
+		inode->delalloc_bytes += len;
+		if (bits & EXTENT_DEFRAG)
+			inode->defrag_bytes += len;
+		spin_unlock(&inode->lock);
+
+		/*
+		 * We don't need to be under the protection of the inode's lock,
+		 * because we are called while holding the inode's io_tree lock
+		 * and are therefore protected against concurrent calls of this
+		 * function and btrfs_clear_delalloc_extent().
+		 */
+		if (!btrfs_is_free_space_inode(inode) && prev_delalloc_bytes == 0)
+			btrfs_add_delalloc_inode(inode);
+	}
+
+	if (!(state->state & EXTENT_DELALLOC_NEW) &&
+	    (bits & EXTENT_DELALLOC_NEW)) {
+		spin_lock(&inode->lock);
+		inode->new_delalloc_bytes += state->end + 1 - state->start;
+		spin_unlock(&inode->lock);
+	}
+}
+
+/*
+ * Once a range is no longer delalloc this function ensures that proper
+ * accounting happens.
+ */
+void btrfs_clear_delalloc_extent(struct btrfs_inode *inode,
+				 struct extent_state *state, u32 bits)
+{
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+	u64 len = state->end + 1 - state->start;
+	u32 num_extents = count_max_extents(fs_info, len);
+
+	lockdep_assert_held(&inode->io_tree.lock);
+
+	if ((state->state & EXTENT_DEFRAG) && (bits & EXTENT_DEFRAG)) {
+		spin_lock(&inode->lock);
+		inode->defrag_bytes -= len;
+		spin_unlock(&inode->lock);
+	}
+
+	/*
+	 * set_bit and clear bit hooks normally require _irqsave/restore
+	 * but in this case, we are only testing for the DELALLOC
+	 * bit, which is only set or cleared with irqs on
+	 */
+	if ((state->state & EXTENT_DELALLOC) && (bits & EXTENT_DELALLOC)) {
+		struct btrfs_root *root = inode->root;
+		u64 new_delalloc_bytes;
+
+		spin_lock(&inode->lock);
+		btrfs_mod_outstanding_extents(inode, -num_extents);
+		spin_unlock(&inode->lock);
+
+		/*
+		 * We don't reserve metadata space for space cache inodes so we
+		 * don't need to call delalloc_release_metadata if there is an
+		 * error.
+		 */
+		if (bits & EXTENT_CLEAR_META_RESV &&
+		    root != fs_info->tree_root)
+			btrfs_delalloc_release_metadata(inode, len, true);
+
+		/* For sanity tests. */
+		if (btrfs_is_testing(fs_info))
+			return;
+
+		if (!btrfs_is_data_reloc_root(root) &&
+		    !btrfs_is_free_space_inode(inode) &&
+		    !(state->state & EXTENT_NORESERVE) &&
+		    (bits & EXTENT_CLEAR_DATA_RESV))
+			btrfs_free_reserved_data_space_noquota(inode, len);
+
+		percpu_counter_add_batch(&fs_info->delalloc_bytes, -len,
+					 fs_info->delalloc_batch);
+		spin_lock(&inode->lock);
+		inode->delalloc_bytes -= len;
+		new_delalloc_bytes = inode->delalloc_bytes;
+		spin_unlock(&inode->lock);
+
+		/*
+		 * We don't need to be under the protection of the inode's lock,
+		 * because we are called while holding the inode's io_tree lock
+		 * and are therefore protected against concurrent calls of this
+		 * function and btrfs_set_delalloc_extent().
+		 */
+		if (!btrfs_is_free_space_inode(inode) && new_delalloc_bytes == 0) {
+			spin_lock(&root->delalloc_lock);
+			btrfs_del_delalloc_inode(inode);
+			spin_unlock(&root->delalloc_lock);
+		}
+	}
+
+	if ((state->state & EXTENT_DELALLOC_NEW) &&
+	    (bits & EXTENT_DELALLOC_NEW)) {
+		spin_lock(&inode->lock);
+		ASSERT(inode->new_delalloc_bytes >= len);
+		inode->new_delalloc_bytes -= len;
+		if (bits & EXTENT_ADD_INODE_BYTES)
+			inode_add_bytes(&inode->vfs_inode, len);
+		spin_unlock(&inode->lock);
+	}
+}
+
+/*
+ * Given an ordered extent and insert all its checksums into the csum tree.
+ *
+ * This happens at IO completion time based on sums calculated at bio
+ * submission time.
+ */
+static int add_pending_csums(struct btrfs_trans_handle *trans,
+			     struct btrfs_ordered_extent *oe)
+{
+	struct btrfs_ordered_sum *sum;
+	struct btrfs_root *csum_root = NULL;
+	int ret;
+
+	list_for_each_entry(sum, &oe->csum_list, list) {
+		if (!csum_root) {
+			csum_root = btrfs_csum_root(trans->fs_info,
+						    sum->logical);
+			if (unlikely(!csum_root)) {
+				btrfs_err(trans->fs_info,
+				  "missing csum root for extent at bytenr %llu",
+					  sum->logical);
+				return -EUCLEAN;
+			}
+		}
+		trans->adding_csums = true;
+		ret = btrfs_insert_data_csums(trans, csum_root, sum);
+		trans->adding_csums = false;
+		if (ret)
+			return ret;
+	}
+	return 0;
+}
+
+static int btrfs_find_new_delalloc_bytes(struct btrfs_inode *inode,
+					 const u64 start,
+					 const u64 len,
+					 struct extent_state **cached_state)
+{
+	u64 search_start = start;
+	const u64 end = start + len - 1;
+
+	while (search_start < end) {
+		const u64 search_len = end - search_start + 1;
+		struct extent_map *em;
+		u64 em_len;
+		int ret = 0;
+
+		em = btrfs_get_extent(inode, NULL, search_start, search_len);
+		if (IS_ERR(em))
+			return PTR_ERR(em);
+
+		if (em->disk_bytenr != EXTENT_MAP_HOLE)
+			goto next;
+
+		em_len = em->len;
+		if (em->start < search_start)
+			em_len -= search_start - em->start;
+		if (em_len > search_len)
+			em_len = search_len;
+
+		ret = btrfs_set_extent_bit(&inode->io_tree, search_start,
+					   search_start + em_len - 1,
+					   EXTENT_DELALLOC_NEW, cached_state);
+next:
+		search_start = btrfs_extent_map_end(em);
+		btrfs_free_extent_map(em);
+		if (ret)
+			return ret;
+	}
+	return 0;
+}
+
+int btrfs_set_extent_delalloc(struct btrfs_inode *inode, u64 start, u64 end,
+			      unsigned int extra_bits,
+			      struct extent_state **cached_state)
+{
+	const u32 blocksize = inode->root->fs_info->sectorsize;
+
+	/* Basic alignment check. */
+	ASSERT(IS_ALIGNED(start, blocksize), "start=%llu blocksize=%u",
+	       start, blocksize);
+	ASSERT(IS_ALIGNED(end + 1, blocksize), "inclusive end=%llu blocksize=%u",
+	       end, blocksize);
+
+	if (start >= i_size_read(&inode->vfs_inode) &&
+	    !(inode->flags & BTRFS_INODE_PREALLOC)) {
+		/*
+		 * There can't be any extents following eof in this case so just
+		 * set the delalloc new bit for the range directly.
+		 */
+		extra_bits |= EXTENT_DELALLOC_NEW;
+	} else {
+		int ret;
+
+		ret = btrfs_find_new_delalloc_bytes(inode, start,
+						    end + 1 - start,
+						    cached_state);
+		if (ret)
+			return ret;
+	}
+
+	return btrfs_set_extent_bit(&inode->io_tree, start, end,
+				    EXTENT_DELALLOC | extra_bits, cached_state);
+}
+
+struct btrfs_writepage_fixup {
+	struct folio *folio;
+	struct btrfs_inode *inode;
+	struct work_struct work;
+};
+
+/*
+ * Do the real fixup work of reserving space for the blocks a folio's fixup
+ * state records. Queued by writepage_fixup() when writeback found the bits set.
+ *
+ * Since the fixup can be cancelled by a task dirtying with a reservation, we must
+ * re-check the state of fixup under the folio lock.
+ */
+static void btrfs_writepage_fixup_worker(struct work_struct *work)
+{
+	struct btrfs_writepage_fixup *fixup =
+		container_of(work, struct btrfs_writepage_fixup, work);
+	struct extent_state *cached_state = NULL;
+	struct extent_changeset *data_reserved = NULL;
+	unsigned long delalloc_bitmap[BITS_TO_LONGS(BTRFS_MAX_BLOCKS_PER_FOLIO)] = { 0 };
+	struct folio *folio = fixup->folio;
+	struct btrfs_inode *inode = fixup->inode;
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+	const unsigned int blocks_per_folio = btrfs_blocks_per_folio(fs_info, folio);
+	const u32 sectorsize = fs_info->sectorsize;
+	const u64 page_start = folio_pos(folio);
+	const u64 page_end = folio_next_pos(folio) - 1;
+	unsigned int start_bit;
+	unsigned int end_bit;
+	unsigned int bit;
+	bool reserved;
+	int ret;
+
+	/*
+	 * We would prefer to reserve under the folio lock when we know exactly
+	 * which blocks need a reservation. Unfortunately, since the reservation
+	 * can go into flushers which can go into writeback, which takes folio
+	 * locks, that is not possible. Therefore, we have to reserve for the
+	 * whole folio here, then release what we didn't end up needing once we
+	 * figure it out.
+	 *
+	 * Also note the slightly strange error checking. If fixup is actually
+	 * not set, we don't need to mark an error on the mapping. So hang on to
+	 * ret until after we lock and find out if we actually care.
+	 */
+	ret = btrfs_delalloc_reserve_space(inode, &data_reserved, page_start,
+					   folio_size(folio));
+	reserved = (ret == 0);
+again:
+	folio_lock(folio);
+
+	if (!folio->mapping || !folio_test_fixup_pending(folio)) {
+		ret = 0;
+		goto out;
+	}
+	if (ret)
+		goto out;
+
+	btrfs_lock_extent(&inode->io_tree, page_start, page_end, &cached_state);
+
+	for (bit = 0; bit < blocks_per_folio; bit++) {
+		struct btrfs_ordered_extent *ordered;
+		const u64 start = page_start + (bit << fs_info->sectorsize_bits);
+
+		if (test_bit(bit, delalloc_bitmap))
+			continue;
+		if (!btrfs_folio_test_fixup(fs_info, folio, start, sectorsize))
+			continue;
+		/*
+		 * Any task that sets EXTENT_DELALLOC clears the fixup bits
+		 * under the folio lock, so it should be impossible to observe
+		 * both under the lock. Setting delalloc twice would wrongly
+		 * double account the space.
+		 */
+		if (IS_ENABLED(CONFIG_BTRFS_DEBUG) &&
+		    unlikely(btrfs_test_range_bit_exists(&inode->io_tree, start,
+							 start + sectorsize - 1,
+							 EXTENT_DELALLOC))) {
+			DEBUG_WARN("fixup worker: delalloc and fixup conflict. ino %llu start %llu",
+				   btrfs_ino(inode), start);
+			btrfs_folio_clear_fixup(fs_info, folio, start, sectorsize);
+			continue;
+		}
+		ordered = btrfs_lookup_ordered_range(inode, start, sectorsize);
+		if (ordered) {
+			trace_btrfs_writepage_fixup_defer(inode, ordered);
+			btrfs_unlock_extent(&inode->io_tree, page_start,
+					    page_end, &cached_state);
+			folio_unlock(folio);
+			btrfs_start_ordered_extent(ordered);
+			btrfs_put_ordered_extent(ordered);
+			goto again;
+		}
+		ret = btrfs_set_extent_delalloc(inode, start,
+						start + sectorsize - 1, 0,
+						&cached_state);
+		if (ret)
+			break;
+		trace_btrfs_writepage_fixup_reserve(inode, start, sectorsize);
+		btrfs_folio_clear_fixup(fs_info, folio, start, sectorsize);
+		set_bit(bit, delalloc_bitmap);
+	}
+
+	btrfs_unlock_extent(&inode->io_tree, page_start, page_end, &cached_state);
+out:
+	if (ret < 0) {
+		/* Failure here is analogous to failure in writeback. */
+		mapping_set_error(folio->mapping, ret);
+		btrfs_folio_clear_fixup_dirty(fs_info, folio, page_start,
+					      folio_size(folio));
+	}
+	if (reserved) {
+		btrfs_delalloc_release_extents(inode, folio_size(folio));
+		for_each_clear_bitrange(start_bit, end_bit, delalloc_bitmap,
+					blocks_per_folio)
+			btrfs_delalloc_release_space(inode, data_reserved,
+				page_start + (start_bit << fs_info->sectorsize_bits),
+				(end_bit - start_bit) << fs_info->sectorsize_bits,
+				true);
+	}
+	folio_unlock(folio);
+	folio_put(folio);
+	kfree(fixup);
+	extent_changeset_free(data_reserved);
+	btrfs_add_delayed_iput(inode);
+}
+
+/*
+ * Queue space reservation fixup work for blocks dirtied without a space reservation.
+ *
+ * Should be used by writeback while holding the folio locked.
+ *
+ * If we fail to queue fixup, then the folio state is unchanged and a future
+ * writeback pass will still see it.
+ */
+void btrfs_queue_writepage_fixup(struct btrfs_inode *inode, struct folio *folio)
+{
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+	struct btrfs_writepage_fixup *fixup;
+
+	/*
+	 * Disallow queueing more fixup during unmount to break the cycle
+	 * of writeback queuing fixup queuing writeback etc.
+	 *
+	 * If it actually hit, then something which was fixup wasn't written
+	 * which we should warn about.
+	 */
+	if (btrfs_fs_closing(fs_info)) {
+		btrfs_warn_rl(fs_info,
+	"dropping unqueued fixup blocks at unmount. root %lld ino %llu folio %llu",
+			      btrfs_root_id(inode->root), btrfs_ino(inode),
+			      folio_pos(folio));
+		btrfs_folio_clear_fixup_dirty(fs_info, folio,
+					      folio_pos(folio), folio_size(folio));
+		return;
+	}
+
+	fixup = kzalloc_obj(*fixup, GFP_NOFS);
+	if (!fixup)
+		return;
+
+	/*
+	 * This is called from within extent_write_cache_pages() which
+	 * has successfully done an igrab(). But that will be released at the
+	 * end of the writeback pass. We need to extend it for the worker as well.
+	 */
+	ihold(&inode->vfs_inode);
+	folio_get(folio);
+	INIT_WORK(&fixup->work, btrfs_writepage_fixup_worker);
+	fixup->folio = folio;
+	fixup->inode = inode;
+	queue_work(fs_info->fixup_workers, &fixup->work);
+}
+
+/*
+ * Clear the old accounting flags and set EXTENT_DELALLOC for the range.
+ *
+ * Return <0 for error, in that case no range has EXTENT_DELALLOC bit cleared or set.
+ */
+int btrfs_reset_extent_delalloc(struct btrfs_inode *inode, u64 start, u64 end,
+				unsigned int extra_bits, struct extent_state **cached_state)
+{
+	const u32 blocksize = inode->root->fs_info->sectorsize;
+
+	/* The @extra_bits can only be EXTENT_NORESERVE for now. */
+	ASSERT(!(extra_bits & ~EXTENT_NORESERVE), "extra_bits=0x%x", extra_bits);
+
+	/* Basic alignment check. */
+	ASSERT(IS_ALIGNED(start, blocksize), "start=%llu blocksize=%u",
+	       start, blocksize);
+	ASSERT(IS_ALIGNED(end + 1, blocksize), "inclusive end=%llu blocksize=%u",
+	       end, blocksize);
+
+	/*
+	 * Check and set DELALLOC_NEW flag, this needs to search tree thus can
+	 * fail early.  Thus we want to do this before clearing EXTENT_DELALLOC.
+	 */
+	if (start >= i_size_read(&inode->vfs_inode) &&
+	    !(inode->flags & BTRFS_INODE_PREALLOC)) {
+		/*
+		 * There can't be any extents following EOF in this case so just
+		 * set the delalloc new bit for the range directly.
+		 */
+		extra_bits |= EXTENT_DELALLOC_NEW;
+	} else {
+		int ret;
+
+		ret = btrfs_find_new_delalloc_bytes(inode, start, end + 1 - start,
+						    NULL);
+		if (unlikely(ret))
+			return ret;
+	}
+	/* Clear the old accounting as the range may already be dirty. */
+	btrfs_clear_extent_bit(&inode->io_tree, start, end,
+			       EXTENT_DELALLOC | EXTENT_DO_ACCOUNTING |
+			       EXTENT_DEFRAG, cached_state);
+	return btrfs_set_extent_bit(&inode->io_tree, start, end,
+				    EXTENT_DELALLOC | extra_bits, cached_state);
+}
+
+static int insert_reserved_file_extent(struct btrfs_trans_handle *trans,
+				       struct btrfs_inode *inode, u64 file_pos,
+				       struct btrfs_file_extent_item *stack_fi,
+				       const bool update_inode_bytes,
+				       u64 qgroup_reserved)
+{
+	struct btrfs_root *root = inode->root;
+	const u32 sectorsize = root->fs_info->sectorsize;
+	BTRFS_PATH_AUTO_FREE(path);
+	struct extent_buffer *leaf;
+	struct btrfs_key ins;
+	u64 disk_num_bytes = btrfs_stack_file_extent_disk_num_bytes(stack_fi);
+	u64 disk_bytenr = btrfs_stack_file_extent_disk_bytenr(stack_fi);
+	u64 offset = btrfs_stack_file_extent_offset(stack_fi);
+	u64 num_bytes = btrfs_stack_file_extent_num_bytes(stack_fi);
+	u64 ram_bytes = btrfs_stack_file_extent_ram_bytes(stack_fi);
+	struct btrfs_drop_extents_args drop_args = { 0 };
+	int ret;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	/*
+	 * we may be replacing one extent in the tree with another.
+	 * The new extent is pinned in the extent map, and we don't want
+	 * to drop it from the cache until it is completely in the btree.
+	 *
+	 * So, tell btrfs_drop_extents to leave this extent in the cache.
+	 * the caller is expected to unpin it and allow it to be merged
+	 * with the others.
+	 */
+	drop_args.path = path;
+	drop_args.start = file_pos;
+	drop_args.end = file_pos + num_bytes;
+	drop_args.replace_extent = true;
+	drop_args.extent_item_size = sizeof(*stack_fi);
+	ret = btrfs_drop_extents(trans, root, inode, &drop_args);
+	if (ret)
+		return ret;
+
+	if (!drop_args.extent_inserted) {
+		ins.objectid = btrfs_ino(inode);
+		ins.type = BTRFS_EXTENT_DATA_KEY;
+		ins.offset = file_pos;
+
+		ret = btrfs_insert_empty_item(trans, root, path, &ins,
+					      sizeof(*stack_fi));
+		if (ret)
+			return ret;
+	}
+	leaf = path->nodes[0];
+	btrfs_set_stack_file_extent_generation(stack_fi, trans->transid);
+	write_extent_buffer(leaf, stack_fi,
+			btrfs_item_ptr_offset(leaf, path->slots[0]),
+			sizeof(struct btrfs_file_extent_item));
+
+	btrfs_release_path(path);
+
+	/*
+	 * If we dropped an inline extent here, we know the range where it is
+	 * was not marked with the EXTENT_DELALLOC_NEW bit, so we update the
+	 * number of bytes only for that range containing the inline extent.
+	 * The remaining of the range will be processed when clearing the
+	 * EXTENT_DELALLOC_BIT bit through the ordered extent completion.
+	 */
+	if (file_pos == 0 && !IS_ALIGNED(drop_args.bytes_found, sectorsize)) {
+		u64 inline_size = round_down(drop_args.bytes_found, sectorsize);
+
+		inline_size = drop_args.bytes_found - inline_size;
+		btrfs_update_inode_bytes(inode, sectorsize, inline_size);
+		drop_args.bytes_found -= inline_size;
+		num_bytes -= sectorsize;
+	}
+
+	if (update_inode_bytes)
+		btrfs_update_inode_bytes(inode, num_bytes, drop_args.bytes_found);
+
+	ins.objectid = disk_bytenr;
+	ins.type = BTRFS_EXTENT_ITEM_KEY;
+	ins.offset = disk_num_bytes;
+
+	ret = btrfs_inode_set_file_extent_range(inode, file_pos, ram_bytes);
+	if (ret)
+		return ret;
+
+	return btrfs_alloc_reserved_file_extent(trans, root, btrfs_ino(inode),
+						file_pos - offset,
+						qgroup_reserved, &ins);
+}
+
+static void btrfs_release_delalloc_bytes(struct btrfs_fs_info *fs_info,
+					 u64 start, u64 len)
+{
+	struct btrfs_block_group *cache;
+
+	cache = btrfs_lookup_block_group(fs_info, start);
+	ASSERT(cache);
+
+	spin_lock(&cache->lock);
+	cache->delalloc_bytes -= len;
+	spin_unlock(&cache->lock);
+
+	btrfs_put_block_group(cache);
+}
+
+static int insert_ordered_extent_file_extent(struct btrfs_trans_handle *trans,
+					     struct btrfs_ordered_extent *oe)
+{
+	struct btrfs_file_extent_item stack_fi;
+	bool update_inode_bytes;
+	u64 num_bytes = oe->num_bytes;
+	u64 ram_bytes = oe->ram_bytes;
+
+	memset(&stack_fi, 0, sizeof(stack_fi));
+	btrfs_set_stack_file_extent_type(&stack_fi, BTRFS_FILE_EXTENT_REG);
+	btrfs_set_stack_file_extent_disk_bytenr(&stack_fi, oe->disk_bytenr);
+	btrfs_set_stack_file_extent_disk_num_bytes(&stack_fi,
+						   oe->disk_num_bytes);
+	btrfs_set_stack_file_extent_offset(&stack_fi, oe->offset);
+	if (test_bit(BTRFS_ORDERED_TRUNCATED, &oe->flags))
+		num_bytes = oe->truncated_len;
+	btrfs_set_stack_file_extent_num_bytes(&stack_fi, num_bytes);
+	btrfs_set_stack_file_extent_ram_bytes(&stack_fi, ram_bytes);
+	btrfs_set_stack_file_extent_compression(&stack_fi, oe->compress_type);
+	/* Encryption and other encoding is reserved and all 0 */
+
+	/*
+	 * For delalloc, when completing an ordered extent we update the inode's
+	 * bytes when clearing the range in the inode's io tree, so pass false
+	 * as the argument 'update_inode_bytes' to insert_reserved_file_extent(),
+	 * except if the ordered extent was truncated.
+	 */
+	update_inode_bytes = test_bit(BTRFS_ORDERED_DIRECT, &oe->flags) ||
+			     test_bit(BTRFS_ORDERED_ENCODED, &oe->flags) ||
+			     test_bit(BTRFS_ORDERED_TRUNCATED, &oe->flags);
+
+	return insert_reserved_file_extent(trans, oe->inode,
+					   oe->file_offset, &stack_fi,
+					   update_inode_bytes, oe->qgroup_rsv);
+}
+
+/*
+ * As ordered data IO finishes, this gets called so we can finish
+ * an ordered extent if the range of bytes in the file it covers are
+ * fully written.
+ */
+int btrfs_finish_one_ordered(struct btrfs_ordered_extent *ordered_extent)
+{
+	struct btrfs_inode *inode = ordered_extent->inode;
+	struct btrfs_root *root = inode->root;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_trans_handle *trans = NULL;
+	struct extent_io_tree *io_tree = &inode->io_tree;
+	struct extent_state *cached_state = NULL;
+	u64 start, end;
+	int compress_type = 0;
+	int ret = 0;
+	u64 logical_len = ordered_extent->num_bytes;
+	bool freespace_inode;
+	bool truncated = false;
+	bool clear_reserved_extent = true;
+	unsigned int clear_bits = 0;
+
+	start = ordered_extent->file_offset;
+	end = start + ordered_extent->num_bytes - 1;
+
+	if (!test_bit(BTRFS_ORDERED_NOCOW, &ordered_extent->flags) &&
+	    !test_bit(BTRFS_ORDERED_PREALLOC, &ordered_extent->flags) &&
+	    !test_bit(BTRFS_ORDERED_DIRECT, &ordered_extent->flags) &&
+	    !test_bit(BTRFS_ORDERED_ENCODED, &ordered_extent->flags))
+		clear_bits |= EXTENT_DELALLOC_NEW;
+
+	if (!test_bit(BTRFS_ORDERED_NOCOW, &ordered_extent->flags))
+		clear_bits |= EXTENT_DEFRAG;
+
+	freespace_inode = btrfs_is_free_space_inode(inode);
+	if (!freespace_inode)
+		btrfs_lockdep_acquire(fs_info, btrfs_ordered_extent);
+
+	if (unlikely(test_bit(BTRFS_ORDERED_IOERR, &ordered_extent->flags))) {
+		ret = -EIO;
+		goto out;
+	}
+
+	ret = btrfs_zone_finish_endio(fs_info, ordered_extent->disk_bytenr,
+				      ordered_extent->disk_num_bytes);
+	if (ret)
+		goto out;
+
+	if (test_bit(BTRFS_ORDERED_TRUNCATED, &ordered_extent->flags)) {
+		truncated = true;
+		logical_len = ordered_extent->truncated_len;
+		/* Truncated the entire extent, don't bother adding */
+		if (!logical_len)
+			goto out;
+	}
+
+	/*
+	 * If it's a COW write we need to lock the extent range as we will be
+	 * inserting/replacing file extent items and unpinning an extent map.
+	 * This must be taken before joining a transaction, as it's a higher
+	 * level lock (like the inode's VFS lock), otherwise we can run into an
+	 * ABBA deadlock with other tasks (transactions work like a lock,
+	 * depending on their current state).
+	 */
+	if (!test_bit(BTRFS_ORDERED_NOCOW, &ordered_extent->flags)) {
+		clear_bits |= EXTENT_LOCKED | EXTENT_FINISHING_ORDERED;
+		btrfs_lock_extent_bits(io_tree, start, end,
+				       EXTENT_LOCKED | EXTENT_FINISHING_ORDERED,
+				       &cached_state);
+	}
+
+	if (freespace_inode)
+		trans = btrfs_join_transaction_spacecache(root);
+	else
+		trans = btrfs_join_transaction(root);
+	if (IS_ERR(trans)) {
+		ret = PTR_ERR(trans);
+		trans = NULL;
+		goto out;
+	}
+
+	trans->block_rsv = &inode->block_rsv;
+
+	ret = btrfs_insert_raid_extent(trans, ordered_extent);
+	if (unlikely(ret)) {
+		btrfs_abort_transaction(trans, ret);
+		goto out;
+	}
+
+	if (test_bit(BTRFS_ORDERED_NOCOW, &ordered_extent->flags)) {
+		/* Logic error */
+		ASSERT(list_empty(&ordered_extent->csum_list));
+		if (unlikely(!list_empty(&ordered_extent->csum_list))) {
+			ret = -EINVAL;
+			btrfs_abort_transaction(trans, ret);
+			goto out;
+		}
+
+		btrfs_inode_safe_disk_i_size_write(inode, 0);
+		ret = btrfs_update_inode_fallback(trans, inode);
+		if (unlikely(ret)) {
+			/* -ENOMEM or corruption */
+			btrfs_abort_transaction(trans, ret);
+		}
+		goto out;
+	}
+
+	if (test_bit(BTRFS_ORDERED_COMPRESSED, &ordered_extent->flags))
+		compress_type = ordered_extent->compress_type;
+	if (test_bit(BTRFS_ORDERED_PREALLOC, &ordered_extent->flags)) {
+		BUG_ON(compress_type);
+		ret = btrfs_mark_extent_written(trans, inode,
+						ordered_extent->file_offset,
+						ordered_extent->file_offset +
+						logical_len);
+		btrfs_zoned_release_data_reloc_bg(fs_info, ordered_extent->disk_bytenr,
+						  ordered_extent->disk_num_bytes);
+		if (unlikely(ret < 0)) {
+			btrfs_abort_transaction(trans, ret);
+			goto out;
+		}
+	} else {
+		BUG_ON(root == fs_info->tree_root);
+		ret = insert_ordered_extent_file_extent(trans, ordered_extent);
+		if (unlikely(ret < 0)) {
+			btrfs_abort_transaction(trans, ret);
+			goto out;
+		}
+		clear_reserved_extent = false;
+		btrfs_release_delalloc_bytes(fs_info,
+					     ordered_extent->disk_bytenr,
+					     ordered_extent->disk_num_bytes);
+	}
+
+	ret = btrfs_unpin_extent_cache(inode, ordered_extent->file_offset,
+				       ordered_extent->num_bytes, trans->transid);
+	if (unlikely(ret < 0)) {
+		btrfs_abort_transaction(trans, ret);
+		goto out;
+	}
+
+	ret = add_pending_csums(trans, ordered_extent);
+	if (unlikely(ret)) {
+		btrfs_abort_transaction(trans, ret);
+		goto out;
+	}
+
+	/*
+	 * If this is a new delalloc range, clear its new delalloc flag to
+	 * update the inode's number of bytes. This needs to be done first
+	 * before updating the inode item.
+	 */
+	if ((clear_bits & EXTENT_DELALLOC_NEW) &&
+	    !test_bit(BTRFS_ORDERED_TRUNCATED, &ordered_extent->flags))
+		btrfs_clear_extent_bit(&inode->io_tree, start, end,
+				       EXTENT_DELALLOC_NEW | EXTENT_ADD_INODE_BYTES,
+				       &cached_state);
+
+	btrfs_inode_safe_disk_i_size_write(inode, 0);
+	ret = btrfs_update_inode_fallback(trans, inode);
+	if (unlikely(ret)) { /* -ENOMEM or corruption */
+		btrfs_abort_transaction(trans, ret);
+		goto out;
+	}
+out:
+	if (clear_bits)
+		btrfs_clear_extent_bit(&inode->io_tree, start, end, clear_bits,
+				       &cached_state);
+
+	if (trans)
+		btrfs_end_transaction(trans);
+
+	if (ret || truncated) {
+		/*
+		 * If we failed to finish this ordered extent for any reason we
+		 * need to make sure BTRFS_ORDERED_IOERR is set on the ordered
+		 * extent, and mark the inode with the error if it wasn't
+		 * already set.  Any error during writeback would have already
+		 * set the mapping error, so we need to set it if we're the ones
+		 * marking this ordered extent as failed.
+		 */
+		if (ret)
+			btrfs_mark_ordered_extent_error(ordered_extent);
+
+		/*
+		 * Drop extent maps for the part of the extent we didn't write.
+		 *
+		 * We have an exception here for the free_space_inode, this is
+		 * because when we do btrfs_get_extent() on the free space inode
+		 * we will search the commit root.  If this is a new block group
+		 * we won't find anything, and we will trip over the assert in
+		 * writepage where we do ASSERT(em->block_start !=
+		 * EXTENT_MAP_HOLE).
+		 *
+		 * Theoretically we could also skip this for any NOCOW extent as
+		 * we don't mess with the extent map tree in the NOCOW case, but
+		 * for now simply skip this if we are the free space inode.
+		 */
+		if (!btrfs_is_free_space_inode(inode)) {
+			u64 unwritten_start = start;
+
+			if (truncated)
+				unwritten_start += logical_len;
+
+			btrfs_drop_extent_map_range(inode, unwritten_start,
+						    end, false);
+		}
+
+		/*
+		 * If the ordered extent had an IOERR or something else went
+		 * wrong we need to return the space for this ordered extent
+		 * back to the allocator.  We only free the extent in the
+		 * truncated case if we didn't write out the extent at all.
+		 *
+		 * If we made it past insert_reserved_file_extent before we
+		 * errored out then we don't need to do this as the accounting
+		 * has already been done.
+		 */
+		if ((ret || !logical_len) &&
+		    clear_reserved_extent &&
+		    !test_bit(BTRFS_ORDERED_NOCOW, &ordered_extent->flags) &&
+		    !test_bit(BTRFS_ORDERED_PREALLOC, &ordered_extent->flags)) {
+			/*
+			 * Discard the range before returning it back to the
+			 * free space pool
+			 */
+			if (ret && btrfs_test_opt(fs_info, DISCARD_SYNC))
+				btrfs_discard_extent(fs_info,
+						ordered_extent->disk_bytenr,
+						ordered_extent->disk_num_bytes,
+						NULL, true);
+			btrfs_free_reserved_extent(fs_info,
+					ordered_extent->disk_bytenr,
+					ordered_extent->disk_num_bytes, true);
+			/*
+			 * Actually free the qgroup rsv which was released when
+			 * the ordered extent was created.
+			 */
+			btrfs_qgroup_free_refroot(fs_info, btrfs_root_id(inode->root),
+						  ordered_extent->qgroup_rsv,
+						  BTRFS_QGROUP_RSV_DATA);
+		}
+	}
+
+	/*
+	 * This needs to be done to make sure anybody waiting knows we are done
+	 * updating everything for this ordered extent.
+	 */
+	btrfs_remove_ordered_extent(ordered_extent);
+
+	/* once for us */
+	btrfs_put_ordered_extent(ordered_extent);
+	/* once for the tree */
+	btrfs_put_ordered_extent(ordered_extent);
+
+	return ret;
+}
+
+int btrfs_finish_ordered_io(struct btrfs_ordered_extent *ordered)
+{
+	if (btrfs_is_zoned(ordered->inode->root->fs_info) &&
+	    !test_bit(BTRFS_ORDERED_IOERR, &ordered->flags) &&
+	    list_empty(&ordered->bioc_list))
+		btrfs_finish_ordered_zoned(ordered);
+	return btrfs_finish_one_ordered(ordered);
+}
+
+/*
+ * Calculate the checksum of an fs block at physical memory address @paddr,
+ * and save the result to @dest.
+ *
+ * The folio containing @paddr must be large enough to contain a full fs block.
+ */
+void btrfs_calculate_block_csum_folio(struct btrfs_fs_info *fs_info,
+				      const phys_addr_t paddr, u8 *dest)
+{
+	struct folio *folio = page_folio(phys_to_page(paddr));
+	const u32 blocksize = fs_info->sectorsize;
+	const u32 step = min(blocksize, PAGE_SIZE);
+	const u32 nr_steps = blocksize / step;
+	phys_addr_t paddrs[BTRFS_MAX_BLOCKSIZE / PAGE_SIZE];
+
+	/* The full block must be inside the folio. */
+	ASSERT(offset_in_folio(folio, paddr) + blocksize <= folio_size(folio));
+
+	for (int i = 0; i < nr_steps; i++) {
+		u32 pindex = offset_in_folio(folio, paddr + i * step) >> PAGE_SHIFT;
+
+		/*
+		 * For bs <= ps cases, we will only run the loop once, so the offset
+		 * inside the page will only added to paddrs[0].
+		 *
+		 * For bs > ps cases, the block must be page aligned, thus offset
+		 * inside the page will always be 0.
+		 */
+		paddrs[i] = page_to_phys(folio_page(folio, pindex)) + offset_in_page(paddr);
+	}
+	return btrfs_calculate_block_csum_pages(fs_info, paddrs, dest);
+}
+
+/*
+ * Calculate the checksum of a fs block backed by multiple noncontiguous pages
+ * at @paddrs[] and save the result to @dest.
+ *
+ * The folio containing @paddr must be large enough to contain a full fs block.
+ */
+void btrfs_calculate_block_csum_pages(struct btrfs_fs_info *fs_info,
+				      const phys_addr_t paddrs[], u8 *dest)
+{
+	const u32 blocksize = fs_info->sectorsize;
+	const u32 step = min(blocksize, PAGE_SIZE);
+	const u32 nr_steps = blocksize / step;
+	struct btrfs_csum_ctx csum;
+
+	btrfs_csum_init(&csum, fs_info->csum_type);
+	for (int i = 0; i < nr_steps; i++) {
+		const phys_addr_t paddr = paddrs[i];
+		void *kaddr;
+
+		ASSERT(offset_in_page(paddr) + step <= PAGE_SIZE);
+		kaddr = kmap_local_page(phys_to_page(paddr)) + offset_in_page(paddr);
+		btrfs_csum_update(&csum, kaddr, step);
+		kunmap_local(kaddr);
+	}
+	btrfs_csum_final(&csum, dest);
+}
+
+/*
+ * Verify the checksum for a single sector without any extra action that depend
+ * on the type of I/O.
+ *
+ * @kaddr must be a properly kmapped address.
+ */
+int btrfs_check_block_csum(struct btrfs_fs_info *fs_info, phys_addr_t paddr, u8 *csum,
+			   const u8 * const csum_expected)
+{
+	btrfs_calculate_block_csum_folio(fs_info, paddr, csum);
+	if (unlikely(memcmp(csum, csum_expected, fs_info->csum_size) != 0))
+		return -EIO;
+	return 0;
+}
+
+/*
+ * Verify the checksum of a single data sector, which can be scattered at
+ * different noncontiguous pages.
+ *
+ * @bbio:	btrfs_io_bio which contains the csum
+ * @dev:	device the sector is on
+ * @bio_offset:	offset to the beginning of the bio (in bytes)
+ * @paddrs:	physical addresses which back the fs block
+ *
+ * Check if the checksum on a data block is valid.  When a checksum mismatch is
+ * detected, report the error and fill the corrupted range with zero.
+ *
+ * Return %true if the sector is ok or had no checksum to start with, else %false.
+ */
+bool btrfs_data_csum_ok(struct btrfs_bio *bbio, struct btrfs_device *dev,
+			u32 bio_offset, const phys_addr_t paddrs[])
+{
+	struct btrfs_inode *inode = bbio->inode;
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+	const u32 blocksize = fs_info->sectorsize;
+	const u32 step = min(blocksize, PAGE_SIZE);
+	const u32 nr_steps = blocksize / step;
+	u64 file_offset = bbio->file_offset + bio_offset;
+	u64 end = file_offset + blocksize - 1;
+	u8 *csum_expected;
+	u8 csum[BTRFS_CSUM_SIZE];
+
+	if (!bbio->csum)
+		return true;
+
+	if (btrfs_is_data_reloc_root(inode->root) &&
+	    btrfs_test_range_bit(&inode->io_tree, file_offset, end, EXTENT_NODATASUM,
+				 NULL)) {
+		/* Skip the range without csum for data reloc inode */
+		btrfs_clear_extent_bit(&inode->io_tree, file_offset, end,
+				       EXTENT_NODATASUM, NULL);
+		return true;
+	}
+
+	csum_expected = bbio->csum + (bio_offset >> fs_info->sectorsize_bits) *
+				fs_info->csum_size;
+	btrfs_calculate_block_csum_pages(fs_info, paddrs, csum);
+	if (unlikely(memcmp(csum, csum_expected, fs_info->csum_size) != 0))
+		goto zeroit;
+	return true;
+
+zeroit:
+	btrfs_print_data_csum_error(inode, file_offset, csum, csum_expected,
+				    bbio->mirror_num);
+	if (dev)
+		btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_CORRUPTION_ERRS);
+	for (int i = 0; i < nr_steps; i++)
+		memzero_page(phys_to_page(paddrs[i]), offset_in_page(paddrs[i]), step);
+	return false;
+}
+
+/*
+ * Perform a delayed iput on @inode.
+ *
+ * @inode: The inode we want to perform iput on
+ *
+ * This function uses the generic vfs_inode::i_count to track whether we should
+ * just decrement it (in case it's > 1) or if this is the last iput then link
+ * the inode to the delayed iput machinery. Delayed iputs are processed at
+ * transaction commit time/superblock commit/cleaner kthread.
+ */
+void btrfs_add_delayed_iput(struct btrfs_inode *inode)
+{
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+	unsigned long flags;
+
+	if (atomic_add_unless(&inode->vfs_inode.i_count, -1, 1))
+		return;
+
+	WARN_ON_ONCE(test_bit(BTRFS_FS_STATE_NO_DELAYED_IPUT, &fs_info->fs_state));
+	atomic_inc(&fs_info->nr_delayed_iputs);
+	/*
+	 * Need to be irq safe here because we can be called from either an irq
+	 * context (see bio.c and btrfs_put_ordered_extent()) or a non-irq
+	 * context.
+	 */
+	spin_lock_irqsave(&fs_info->delayed_iput_lock, flags);
+	ASSERT(list_empty(&inode->delayed_iput));
+	list_add_tail(&inode->delayed_iput, &fs_info->delayed_iputs);
+	spin_unlock_irqrestore(&fs_info->delayed_iput_lock, flags);
+	if (!test_bit(BTRFS_FS_CLEANER_RUNNING, &fs_info->flags))
+		wake_up_process(fs_info->cleaner_kthread);
+}
+
+static void run_delayed_iput_locked(struct btrfs_fs_info *fs_info,
+				    struct btrfs_inode *inode)
+{
+	list_del_init(&inode->delayed_iput);
+	spin_unlock_irq(&fs_info->delayed_iput_lock);
+	iput(&inode->vfs_inode);
+	if (atomic_dec_and_test(&fs_info->nr_delayed_iputs))
+		wake_up(&fs_info->delayed_iputs_wait);
+	spin_lock_irq(&fs_info->delayed_iput_lock);
+}
+
+static void btrfs_run_delayed_iput(struct btrfs_fs_info *fs_info,
+				   struct btrfs_inode *inode)
+{
+	if (!list_empty(&inode->delayed_iput)) {
+		spin_lock_irq(&fs_info->delayed_iput_lock);
+		if (!list_empty(&inode->delayed_iput))
+			run_delayed_iput_locked(fs_info, inode);
+		spin_unlock_irq(&fs_info->delayed_iput_lock);
+	}
+}
+
+void btrfs_run_delayed_iputs(struct btrfs_fs_info *fs_info)
+{
+	/*
+	 * btrfs_put_ordered_extent() can run in irq context (see bio.c), which
+	 * calls btrfs_add_delayed_iput() and that needs to lock
+	 * fs_info->delayed_iput_lock. So we need to disable irqs here to
+	 * prevent a deadlock.
+	 */
+	spin_lock_irq(&fs_info->delayed_iput_lock);
+	while (!list_empty(&fs_info->delayed_iputs)) {
+		struct btrfs_inode *inode;
+
+		inode = list_first_entry(&fs_info->delayed_iputs,
+				struct btrfs_inode, delayed_iput);
+		run_delayed_iput_locked(fs_info, inode);
+		if (need_resched()) {
+			spin_unlock_irq(&fs_info->delayed_iput_lock);
+			cond_resched();
+			spin_lock_irq(&fs_info->delayed_iput_lock);
+		}
+	}
+	spin_unlock_irq(&fs_info->delayed_iput_lock);
+}
+
+/*
+ * Wait for flushing all delayed iputs
+ *
+ * @fs_info:  the filesystem
+ *
+ * This will wait on any delayed iputs that are currently running with KILLABLE
+ * set.  Once they are all done running we will return, unless we are killed in
+ * which case we return EINTR. This helps in user operations like fallocate etc
+ * that might get blocked on the iputs.
+ *
+ * Return EINTR if we were killed, 0 if nothing's pending
+ */
+int btrfs_wait_on_delayed_iputs(struct btrfs_fs_info *fs_info)
+{
+	int ret = wait_event_killable(fs_info->delayed_iputs_wait,
+			atomic_read(&fs_info->nr_delayed_iputs) == 0);
+	if (ret)
+		return -EINTR;
+	return 0;
+}
+
+/*
+ * This creates an orphan entry for the given inode in case something goes wrong
+ * in the middle of an unlink.
+ */
+int btrfs_orphan_add(struct btrfs_trans_handle *trans,
+		     struct btrfs_inode *inode)
+{
+	int ret;
+
+	ret = btrfs_insert_orphan_item(trans, inode->root, btrfs_ino(inode));
+	if (unlikely(ret && ret != -EEXIST)) {
+		btrfs_abort_transaction(trans, ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+/*
+ * We have done the delete so we can go ahead and remove the orphan item for
+ * this particular inode.
+ */
+static int btrfs_orphan_del(struct btrfs_trans_handle *trans,
+			    struct btrfs_inode *inode)
+{
+	return btrfs_del_orphan_item(trans, inode->root, btrfs_ino(inode));
+}
+
+/*
+ * this cleans up any orphans that may be left on the list from the last use
+ * of this root.
+ */
+int btrfs_orphan_cleanup(struct btrfs_root *root)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	BTRFS_PATH_AUTO_FREE(path);
+	struct extent_buffer *leaf;
+	struct btrfs_key key, found_key;
+	struct btrfs_trans_handle *trans;
+	u64 last_objectid = 0;
+	int ret = 0, nr_unlink = 0;
+
+	if (test_and_set_bit(BTRFS_ROOT_ORPHAN_CLEANUP, &root->state))
+		return 0;
+
+	path = btrfs_alloc_path();
+	if (!path) {
+		ret = -ENOMEM;
+		goto out;
+	}
+	path->reada = READA_BACK;
+
+	key.objectid = BTRFS_ORPHAN_OBJECTID;
+	key.type = BTRFS_ORPHAN_ITEM_KEY;
+	key.offset = (u64)-1;
+
+	while (1) {
+		struct btrfs_inode *inode;
+
+		ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+		if (ret < 0)
+			goto out;
+
+		/*
+		 * if ret == 0 means we found what we were searching for, which
+		 * is weird, but possible, so only screw with path if we didn't
+		 * find the key and see if we have stuff that matches
+		 */
+		if (ret > 0) {
+			ret = 0;
+			if (path->slots[0] == 0)
+				break;
+			path->slots[0]--;
+		}
+
+		/* pull out the item */
+		leaf = path->nodes[0];
+		btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
+
+		/* make sure the item matches what we want */
+		if (found_key.objectid != BTRFS_ORPHAN_OBJECTID)
+			break;
+		if (found_key.type != BTRFS_ORPHAN_ITEM_KEY)
+			break;
+
+		/* release the path since we're done with it */
+		btrfs_release_path(path);
+
+		/*
+		 * this is where we are basically btrfs_lookup, without the
+		 * crossing root thing.  we store the inode number in the
+		 * offset of the orphan item.
+		 */
+
+		if (found_key.offset == last_objectid) {
+			/*
+			 * We found the same inode as before. This means we were
+			 * not able to remove its items via eviction triggered
+			 * by an iput(). A transaction abort may have happened,
+			 * due to -ENOSPC for example, so try to grab the error
+			 * that lead to a transaction abort, if any.
+			 */
+			btrfs_err(fs_info,
+				  "Error removing orphan entry, stopping orphan cleanup");
+			ret = BTRFS_FS_ERROR(fs_info) ?: -EINVAL;
+			goto out;
+		}
+
+		last_objectid = found_key.offset;
+
+		found_key.objectid = found_key.offset;
+		found_key.type = BTRFS_INODE_ITEM_KEY;
+		found_key.offset = 0;
+		inode = btrfs_iget(last_objectid, root);
+		if (IS_ERR(inode)) {
+			ret = PTR_ERR(inode);
+			inode = NULL;
+			if (ret != -ENOENT)
+				goto out;
+		}
+
+		if (!inode && root == fs_info->tree_root) {
+			struct btrfs_root *dead_root;
+			bool is_dead_root = false;
+
+			/*
+			 * This is an orphan in the tree root. Currently these
+			 * could come from 2 sources:
+			 *  a) a root (snapshot/subvolume) deletion in progress
+			 *  b) a free space cache inode
+			 * We need to distinguish those two, as the orphan item
+			 * for a root must not get deleted before the deletion
+			 * of the snapshot/subvolume's tree completes.
+			 *
+			 * btrfs_find_orphan_roots() ran before us, which has
+			 * found all deleted roots and loaded them into
+			 * fs_info->fs_roots_radix. So here we can find if an
+			 * orphan item corresponds to a deleted root by looking
+			 * up the root from that radix tree.
+			 */
+
+			spin_lock(&fs_info->fs_roots_radix_lock);
+			dead_root = radix_tree_lookup(&fs_info->fs_roots_radix,
+							 (unsigned long)found_key.objectid);
+			if (dead_root && btrfs_root_refs(&dead_root->root_item) == 0)
+				is_dead_root = true;
+			spin_unlock(&fs_info->fs_roots_radix_lock);
+
+			if (is_dead_root) {
+				/* prevent this orphan from being found again */
+				key.offset = found_key.objectid - 1;
+				continue;
+			}
+
+		}
+
+		/*
+		 * If we have an inode with links, there are a couple of
+		 * possibilities:
+		 *
+		 * 1. We were halfway through creating fsverity metadata for the
+		 * file. In that case, the orphan item represents incomplete
+		 * fsverity metadata which must be cleaned up with
+		 * btrfs_drop_verity_items and deleting the orphan item.
+
+		 * 2. Old kernels (before v3.12) used to create an
+		 * orphan item for truncate indicating that there were possibly
+		 * extent items past i_size that needed to be deleted. In v3.12,
+		 * truncate was changed to update i_size in sync with the extent
+		 * items, but the (useless) orphan item was still created. Since
+		 * v4.18, we don't create the orphan item for truncate at all.
+		 *
+		 * So, this item could mean that we need to do a truncate, but
+		 * only if this filesystem was last used on a pre-v3.12 kernel
+		 * and was not cleanly unmounted. The odds of that are quite
+		 * slim, and it's a pain to do the truncate now, so just delete
+		 * the orphan item.
+		 *
+		 * It's also possible that this orphan item was supposed to be
+		 * deleted but wasn't. The inode number may have been reused,
+		 * but either way, we can delete the orphan item.
+		 */
+		if (!inode || inode->vfs_inode.i_nlink) {
+			if (inode) {
+				ret = btrfs_drop_verity_items(inode);
+				iput(&inode->vfs_inode);
+				inode = NULL;
+				if (ret)
+					goto out;
+			}
+			trans = btrfs_start_transaction(root, 1);
+			if (IS_ERR(trans)) {
+				ret = PTR_ERR(trans);
+				goto out;
+			}
+			btrfs_debug(fs_info, "auto deleting %Lu",
+				    found_key.objectid);
+			ret = btrfs_del_orphan_item(trans, root,
+						    found_key.objectid);
+			btrfs_end_transaction(trans);
+			if (ret)
+				goto out;
+			continue;
+		}
+
+		nr_unlink++;
+
+		/* this will do delete_inode and everything for us */
+		iput(&inode->vfs_inode);
+	}
+	/* release the path since we're done with it */
+	btrfs_release_path(path);
+
+	if (test_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED, &root->state)) {
+		trans = btrfs_join_transaction(root);
+		if (!IS_ERR(trans))
+			btrfs_end_transaction(trans);
+	}
+
+	if (nr_unlink)
+		btrfs_debug(fs_info, "unlinked %d orphans", nr_unlink);
+
+out:
+	if (ret)
+		btrfs_err(fs_info, "could not do orphan cleanup %pe", ERR_PTR(ret));
+	return ret;
+}
+
+/*
+ * Look ahead in the leaf for xattrs. If we don't find any then we know there
+ * can't be any ACLs.
+ *
+ * @leaf:       the eb leaf where to search
+ * @slot:       the slot the inode is in
+ * @objectid:   the objectid of the inode
+ *
+ * Return true if there is xattr/ACL, false otherwise.
+ */
+static noinline bool acls_after_inode_item(struct extent_buffer *leaf,
+					   int slot, u64 objectid,
+					   int *first_xattr_slot)
+{
+	u32 nritems = btrfs_header_nritems(leaf);
+	struct btrfs_key found_key;
+	static u64 xattr_access = 0;
+	static u64 xattr_default = 0;
+	int scanned = 0;
+
+	if (!xattr_access) {
+		xattr_access = btrfs_name_hash(XATTR_NAME_POSIX_ACL_ACCESS,
+					strlen(XATTR_NAME_POSIX_ACL_ACCESS));
+		xattr_default = btrfs_name_hash(XATTR_NAME_POSIX_ACL_DEFAULT,
+					strlen(XATTR_NAME_POSIX_ACL_DEFAULT));
+	}
+
+	slot++;
+	*first_xattr_slot = -1;
+	while (slot < nritems) {
+		btrfs_item_key_to_cpu(leaf, &found_key, slot);
+
+		/* We found a different objectid, there must be no ACLs. */
+		if (found_key.objectid != objectid)
+			return false;
+
+		/* We found an xattr, assume we've got an ACL. */
+		if (found_key.type == BTRFS_XATTR_ITEM_KEY) {
+			if (*first_xattr_slot == -1)
+				*first_xattr_slot = slot;
+			if (found_key.offset == xattr_access ||
+			    found_key.offset == xattr_default)
+				return true;
+		}
+
+		/*
+		 * We found a key greater than an xattr key, there can't be any
+		 * ACLs later on.
+		 */
+		if (found_key.type > BTRFS_XATTR_ITEM_KEY)
+			return false;
+
+		slot++;
+		scanned++;
+
+		/*
+		 * The item order goes like:
+		 * - inode
+		 * - inode backrefs
+		 * - xattrs
+		 * - extents,
+		 *
+		 * so if there are lots of hard links to an inode there can be
+		 * a lot of backrefs.  Don't waste time searching too hard,
+		 * this is just an optimization.
+		 */
+		if (scanned >= 8)
+			break;
+	}
+	/*
+	 * We hit the end of the leaf before we found an xattr or something
+	 * larger than an xattr.  We have to assume the inode has ACLs.
+	 */
+	if (*first_xattr_slot == -1)
+		*first_xattr_slot = slot;
+	return true;
+}
+
+static int btrfs_init_file_extent_tree(struct btrfs_inode *inode)
+{
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+
+	if (WARN_ON_ONCE(inode->file_extent_tree))
+		return 0;
+	if (btrfs_fs_incompat(fs_info, NO_HOLES))
+		return 0;
+	if (!S_ISREG(inode->vfs_inode.i_mode))
+		return 0;
+	if (btrfs_is_free_space_inode(inode))
+		return 0;
+
+	inode->file_extent_tree = kmalloc_obj(struct extent_io_tree);
+	if (!inode->file_extent_tree)
+		return -ENOMEM;
+
+	btrfs_extent_io_tree_init(fs_info, inode->file_extent_tree,
+				  IO_TREE_INODE_FILE_EXTENT);
+	/* Lockdep class is set only for the file extent tree. */
+	lockdep_set_class(&inode->file_extent_tree->lock, &file_extent_tree_class);
+
+	return 0;
+}
+
+static int btrfs_add_inode_to_root(struct btrfs_inode *inode, bool prealloc)
+{
+	struct btrfs_root *root = inode->root;
+	struct btrfs_inode *existing;
+	const u64 ino = btrfs_ino(inode);
+	int ret;
+
+	if (inode_unhashed(&inode->vfs_inode))
+		return 0;
+
+	if (prealloc) {
+		ret = xa_reserve(&root->inodes, ino, GFP_NOFS);
+		if (ret)
+			return ret;
+	}
+
+	existing = xa_store(&root->inodes, ino, inode, GFP_ATOMIC);
+
+	if (xa_is_err(existing)) {
+		ret = xa_err(existing);
+		ASSERT(ret != -EINVAL);
+		ASSERT(ret != -ENOMEM);
+		return ret;
+	} else if (existing) {
+		WARN_ON(!(inode_state_read_once(&existing->vfs_inode) & (I_WILL_FREE | I_FREEING)));
+	}
+
+	return 0;
+}
+
+/*
+ * Read a locked inode from the btree into the in-memory inode and add it to
+ * its root list/tree.
+ *
+ * On failure clean up the inode.
+ */
+static int btrfs_read_locked_inode(struct btrfs_inode *inode, struct btrfs_path *path)
+{
+	struct btrfs_root *root = inode->root;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct extent_buffer *leaf;
+	struct btrfs_inode_item *inode_item;
+	struct inode *vfs_inode = &inode->vfs_inode;
+	struct btrfs_key location;
+	unsigned long ptr;
+	int maybe_acls;
+	u32 rdev;
+	int ret;
+	bool filled = false;
+	int first_xattr_slot;
+
+	ret = btrfs_fill_inode(inode, &rdev);
+	if (!ret)
+		filled = true;
+
+	ASSERT(path);
+
+	btrfs_get_inode_key(inode, &location);
+
+	ret = btrfs_lookup_inode(NULL, root, path, &location, 0);
+	if (ret) {
+		/*
+		 * ret > 0 can come from btrfs_search_slot called by
+		 * btrfs_lookup_inode(), this means the inode was not found.
+		 */
+		if (ret > 0)
+			ret = -ENOENT;
+		goto out;
+	}
+
+	leaf = path->nodes[0];
+
+	if (filled)
+		goto cache_index;
+
+	inode_item = btrfs_item_ptr(leaf, path->slots[0],
+				    struct btrfs_inode_item);
+	vfs_inode->i_mode = btrfs_inode_mode(leaf, inode_item);
+	set_nlink(vfs_inode, btrfs_inode_nlink(leaf, inode_item));
+	i_uid_write(vfs_inode, btrfs_inode_uid(leaf, inode_item));
+	i_gid_write(vfs_inode, btrfs_inode_gid(leaf, inode_item));
+	btrfs_i_size_write(inode, btrfs_inode_size(leaf, inode_item));
+
+	inode_set_atime(vfs_inode, btrfs_timespec_sec(leaf, &inode_item->atime),
+			btrfs_timespec_nsec(leaf, &inode_item->atime));
+
+	inode_set_mtime(vfs_inode, btrfs_timespec_sec(leaf, &inode_item->mtime),
+			btrfs_timespec_nsec(leaf, &inode_item->mtime));
+
+	inode_set_ctime(vfs_inode, btrfs_timespec_sec(leaf, &inode_item->ctime),
+			btrfs_timespec_nsec(leaf, &inode_item->ctime));
+
+	inode->i_otime_sec = btrfs_timespec_sec(leaf, &inode_item->otime);
+	inode->i_otime_nsec = btrfs_timespec_nsec(leaf, &inode_item->otime);
+
+	inode_set_bytes(vfs_inode, btrfs_inode_nbytes(leaf, inode_item));
+	inode->generation = btrfs_inode_generation(leaf, inode_item);
+	inode->last_trans = btrfs_inode_transid(leaf, inode_item);
+
+	inode_set_iversion_queried(vfs_inode, btrfs_inode_sequence(leaf, inode_item));
+	vfs_inode->i_generation = inode->generation;
+	vfs_inode->i_rdev = 0;
+	rdev = btrfs_inode_rdev(leaf, inode_item);
+
+	if (S_ISDIR(vfs_inode->i_mode))
+		inode->index_cnt = (u64)-1;
+
+	btrfs_inode_split_flags(btrfs_inode_flags(leaf, inode_item),
+				&inode->flags, &inode->ro_flags);
+
+cache_index:
+	btrfs_update_inode_mapping_flags(inode);
+	btrfs_set_inode_mapping_order(inode);
+
+	/*
+	 * If we were modified in the current generation and evicted from memory
+	 * and then re-read we need to do a full sync since we don't have any
+	 * idea about which extents were modified before we were evicted from
+	 * cache.
+	 *
+	 * This is required for both inode re-read from disk and delayed inode
+	 * in the delayed_nodes xarray.
+	 */
+	if (inode->last_trans == btrfs_get_fs_generation(fs_info))
+		set_bit(BTRFS_INODE_NEEDS_FULL_SYNC, &inode->runtime_flags);
+
+	/*
+	 * We don't persist the id of the transaction where an unlink operation
+	 * against the inode was last made. So here we assume the inode might
+	 * have been evicted, and therefore the exact value of last_unlink_trans
+	 * lost, and set it to last_trans to avoid metadata inconsistencies
+	 * between the inode and its parent if the inode is fsync'ed and the log
+	 * replayed. For example, in the scenario:
+	 *
+	 * touch mydir/foo
+	 * ln mydir/foo mydir/bar
+	 * sync
+	 * unlink mydir/bar
+	 * echo 2 > /proc/sys/vm/drop_caches   # evicts inode
+	 * xfs_io -c fsync mydir/foo
+	 * <power failure>
+	 * mount fs, triggers fsync log replay
+	 *
+	 * We must make sure that when we fsync our inode foo we also log its
+	 * parent inode, otherwise after log replay the parent still has the
+	 * dentry with the "bar" name but our inode foo has a link count of 1
+	 * and doesn't have an inode ref with the name "bar" anymore.
+	 *
+	 * Setting last_unlink_trans to last_trans is a pessimistic approach,
+	 * but it guarantees correctness at the expense of occasional full
+	 * transaction commits on fsync if our inode is a directory, or if our
+	 * inode is not a directory, logging its parent unnecessarily.
+	 */
+	inode->last_unlink_trans = inode->last_trans;
+
+	/*
+	 * Same logic as for last_unlink_trans. We don't persist the generation
+	 * of the last transaction where this inode was used for a reflink
+	 * operation, so after eviction and reloading the inode we must be
+	 * pessimistic and assume the last transaction that modified the inode.
+	 */
+	inode->last_reflink_trans = inode->last_trans;
+
+	path->slots[0]++;
+	if (vfs_inode->i_nlink != 1 ||
+	    path->slots[0] >= btrfs_header_nritems(leaf))
+		goto cache_acl;
+
+	btrfs_item_key_to_cpu(leaf, &location, path->slots[0]);
+	if (location.objectid != btrfs_ino(inode))
+		goto cache_acl;
+
+	ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
+	if (location.type == BTRFS_INODE_REF_KEY) {
+		struct btrfs_inode_ref *ref;
+
+		ref = (struct btrfs_inode_ref *)ptr;
+		inode->dir_index = btrfs_inode_ref_index(leaf, ref);
+	} else if (location.type == BTRFS_INODE_EXTREF_KEY) {
+		struct btrfs_inode_extref *extref;
+
+		extref = (struct btrfs_inode_extref *)ptr;
+		inode->dir_index = btrfs_inode_extref_index(leaf, extref);
+	}
+cache_acl:
+	/*
+	 * try to precache a NULL acl entry for files that don't have
+	 * any xattrs or acls
+	 */
+	maybe_acls = acls_after_inode_item(leaf, path->slots[0],
+					   btrfs_ino(inode), &first_xattr_slot);
+	if (first_xattr_slot != -1) {
+		path->slots[0] = first_xattr_slot;
+		ret = btrfs_load_inode_props(inode, path);
+		if (ret)
+			btrfs_err(fs_info,
+				  "error loading props for ino %llu (root %llu): %pe",
+				  btrfs_ino(inode), btrfs_root_id(root), ERR_PTR(ret));
+	}
+
+	/*
+	 * We don't need the path anymore, so release it to avoid holding a read
+	 * lock on a leaf while calling btrfs_init_file_extent_tree(), which can
+	 * allocate memory that triggers reclaim (GFP_KERNEL) and cause a locking
+	 * dependency.
+	 */
+	btrfs_release_path(path);
+
+	ret = btrfs_init_file_extent_tree(inode);
+	if (ret)
+		goto out;
+	btrfs_inode_set_file_extent_range(inode, 0,
+			  round_up(i_size_read(vfs_inode), fs_info->sectorsize));
+
+	if (!maybe_acls)
+		cache_no_acl(vfs_inode);
+
+	switch (vfs_inode->i_mode & S_IFMT) {
+	case S_IFREG:
+		vfs_inode->i_mapping->a_ops = &btrfs_aops;
+		vfs_inode->i_fop = &btrfs_file_operations;
+		vfs_inode->i_op = &btrfs_file_inode_operations;
+		break;
+	case S_IFDIR:
+		vfs_inode->i_fop = &btrfs_dir_file_operations;
+		vfs_inode->i_op = &btrfs_dir_inode_operations;
+		break;
+	case S_IFLNK:
+		vfs_inode->i_op = &btrfs_symlink_inode_operations;
+		inode_nohighmem(vfs_inode);
+		vfs_inode->i_mapping->a_ops = &btrfs_aops;
+		break;
+	default:
+		vfs_inode->i_op = &btrfs_special_inode_operations;
+		init_special_inode(vfs_inode, vfs_inode->i_mode, rdev);
+		break;
+	}
+
+	btrfs_sync_inode_flags_to_i_flags(inode);
+
+	ret = btrfs_add_inode_to_root(inode, true);
+	if (ret)
+		goto out;
+
+	return 0;
+out:
+	/*
+	 * We may have a read locked leaf and iget_failed() triggers inode
+	 * eviction which needs to release the delayed inode and that needs
+	 * to lock the delayed inode's mutex. This can cause a ABBA deadlock
+	 * with a task running delayed items, as that require first locking
+	 * the delayed inode's mutex and then modifying its subvolume btree.
+	 * So release the path before iget_failed().
+	 */
+	btrfs_release_path(path);
+	iget_failed(vfs_inode);
+	return ret;
+}
+
+/*
+ * given a leaf and an inode, copy the inode fields into the leaf
+ */
+static void fill_inode_item(struct btrfs_trans_handle *trans,
+			    struct extent_buffer *leaf,
+			    struct btrfs_inode_item *item,
+			    struct inode *inode)
+{
+	u64 flags;
+
+	btrfs_set_inode_uid(leaf, item, i_uid_read(inode));
+	btrfs_set_inode_gid(leaf, item, i_gid_read(inode));
+	btrfs_set_inode_size(leaf, item, BTRFS_I(inode)->disk_i_size);
+	btrfs_set_inode_mode(leaf, item, inode->i_mode);
+	btrfs_set_inode_nlink(leaf, item, inode->i_nlink);
+
+	btrfs_set_timespec_sec(leaf, &item->atime, inode_get_atime_sec(inode));
+	btrfs_set_timespec_nsec(leaf, &item->atime, inode_get_atime_nsec(inode));
+
+	btrfs_set_timespec_sec(leaf, &item->mtime, inode_get_mtime_sec(inode));
+	btrfs_set_timespec_nsec(leaf, &item->mtime, inode_get_mtime_nsec(inode));
+
+	btrfs_set_timespec_sec(leaf, &item->ctime, inode_get_ctime_sec(inode));
+	btrfs_set_timespec_nsec(leaf, &item->ctime, inode_get_ctime_nsec(inode));
+
+	btrfs_set_timespec_sec(leaf, &item->otime, BTRFS_I(inode)->i_otime_sec);
+	btrfs_set_timespec_nsec(leaf, &item->otime, BTRFS_I(inode)->i_otime_nsec);
+
+	btrfs_set_inode_nbytes(leaf, item, inode_get_bytes(inode));
+	btrfs_set_inode_generation(leaf, item, BTRFS_I(inode)->generation);
+	btrfs_set_inode_sequence(leaf, item, inode_peek_iversion(inode));
+	btrfs_set_inode_transid(leaf, item, trans->transid);
+	btrfs_set_inode_rdev(leaf, item, inode->i_rdev);
+	flags = btrfs_inode_combine_flags(BTRFS_I(inode)->flags,
+					  BTRFS_I(inode)->ro_flags);
+	btrfs_set_inode_flags(leaf, item, flags);
+	btrfs_set_inode_block_group(leaf, item, 0);
+}
+
+/*
+ * copy everything in the in-memory inode into the btree.
+ */
+static noinline int btrfs_update_inode_item(struct btrfs_trans_handle *trans,
+					    struct btrfs_inode *inode)
+{
+	struct btrfs_inode_item *inode_item;
+	BTRFS_PATH_AUTO_FREE(path);
+	struct extent_buffer *leaf;
+	struct btrfs_key key;
+	int ret;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	btrfs_get_inode_key(inode, &key);
+	ret = btrfs_lookup_inode(trans, inode->root, path, &key, 1);
+	if (ret) {
+		if (ret > 0)
+			ret = -ENOENT;
+		return ret;
+	}
+
+	leaf = path->nodes[0];
+	inode_item = btrfs_item_ptr(leaf, path->slots[0],
+				    struct btrfs_inode_item);
+
+	fill_inode_item(trans, leaf, inode_item, &inode->vfs_inode);
+	btrfs_set_inode_last_trans(trans, inode);
+	return 0;
+}
+
+/*
+ * copy everything in the in-memory inode into the btree.
+ */
+int btrfs_update_inode(struct btrfs_trans_handle *trans,
+		       struct btrfs_inode *inode)
+{
+	struct btrfs_root *root = inode->root;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	int ret;
+
+	/*
+	 * If the inode is a free space inode, we can deadlock during commit
+	 * if we put it into the delayed code.
+	 *
+	 * The data relocation inode should also be directly updated
+	 * without delay
+	 */
+	if (!btrfs_is_free_space_inode(inode)
+	    && !btrfs_is_data_reloc_root(root)
+	    && !test_bit(BTRFS_FS_LOG_RECOVERING, &fs_info->flags)) {
+		btrfs_update_root_times(trans, root);
+
+		ret = btrfs_delayed_update_inode(trans, inode);
+		if (!ret)
+			btrfs_set_inode_last_trans(trans, inode);
+		return ret;
+	}
+
+	return btrfs_update_inode_item(trans, inode);
+}
+
+int btrfs_update_inode_fallback(struct btrfs_trans_handle *trans,
+				struct btrfs_inode *inode)
+{
+	int ret;
+
+	ret = btrfs_update_inode(trans, inode);
+	if (ret == -ENOSPC)
+		return btrfs_update_inode_item(trans, inode);
+	return ret;
+}
+
+static void update_time_after_link_or_unlink(struct btrfs_inode *dir)
+{
+	struct timespec64 now;
+
+	/*
+	 * If we are replaying a log tree, we do not want to update the mtime
+	 * and ctime of the parent directory with the current time, since the
+	 * log replay procedure is responsible for setting them to their correct
+	 * values (the ones it had when the fsync was done).
+	 */
+	if (test_bit(BTRFS_FS_LOG_RECOVERING, &dir->root->fs_info->flags))
+		return;
+
+	now = inode_set_ctime_current(&dir->vfs_inode);
+	inode_set_mtime_to_ts(&dir->vfs_inode, now);
+}
+
+/*
+ * unlink helper that gets used here in inode.c and in the tree logging
+ * recovery code.  It remove a link in a directory with a given name, and
+ * also drops the back refs in the inode to the directory
+ */
+static int __btrfs_unlink_inode(struct btrfs_trans_handle *trans,
+				struct btrfs_inode *dir,
+				struct btrfs_inode *inode,
+				const struct fscrypt_str *name,
+				struct btrfs_rename_ctx *rename_ctx)
+{
+	struct btrfs_root *root = dir->root;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_path *path;
+	int ret = 0;
+	struct btrfs_dir_item *di;
+	u64 index;
+	u64 ino = btrfs_ino(inode);
+	u64 dir_ino = btrfs_ino(dir);
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	di = btrfs_lookup_dir_item(trans, root, path, dir_ino, name, -1);
+	if (IS_ERR_OR_NULL(di)) {
+		btrfs_free_path(path);
+		return di ? PTR_ERR(di) : -ENOENT;
+	}
+	ret = btrfs_delete_one_dir_name(trans, root, path, di);
+	/*
+	 * Down the call chains below we'll also need to allocate a path, so no
+	 * need to hold on to this one for longer than necessary.
+	 */
+	btrfs_free_path(path);
+	if (ret)
+		return ret;
+
+	/*
+	 * If we don't have dir index, we have to get it by looking up
+	 * the inode ref, since we get the inode ref, remove it directly,
+	 * it is unnecessary to do delayed deletion.
+	 *
+	 * But if we have dir index, needn't search inode ref to get it.
+	 * Since the inode ref is close to the inode item, it is better
+	 * that we delay to delete it, and just do this deletion when
+	 * we update the inode item.
+	 */
+	if (inode->dir_index) {
+		ret = btrfs_delayed_delete_inode_ref(inode);
+		if (!ret) {
+			index = inode->dir_index;
+			goto skip_backref;
+		}
+	}
+
+	ret = btrfs_del_inode_ref(trans, root, name, ino, dir_ino, &index);
+	if (unlikely(ret)) {
+		btrfs_crit(fs_info,
+	   "failed to delete reference to %.*s, root %llu inode %llu parent %llu",
+			   name->len, name->name, btrfs_root_id(root), ino, dir_ino);
+		btrfs_abort_transaction(trans, ret);
+		return ret;
+	}
+skip_backref:
+	if (rename_ctx)
+		rename_ctx->index = index;
+
+	ret = btrfs_delete_delayed_dir_index(trans, dir, index);
+	if (unlikely(ret)) {
+		btrfs_abort_transaction(trans, ret);
+		return ret;
+	}
+
+	/*
+	 * If we are in a rename context, we don't need to update anything in the
+	 * log. That will be done later during the rename by btrfs_log_new_name().
+	 * Besides that, doing it here would only cause extra unnecessary btree
+	 * operations on the log tree, increasing latency for applications.
+	 */
+	if (!rename_ctx) {
+		btrfs_del_inode_ref_in_log(trans, name, inode, dir);
+		btrfs_del_dir_entries_in_log(trans, name, dir, index);
+	}
+
+	/*
+	 * If we have a pending delayed iput we could end up with the final iput
+	 * being run in btrfs-cleaner context.  If we have enough of these built
+	 * up we can end up burning a lot of time in btrfs-cleaner without any
+	 * way to throttle the unlinks.  Since we're currently holding a ref on
+	 * the inode we can run the delayed iput here without any issues as the
+	 * final iput won't be done until after we drop the ref we're currently
+	 * holding.
+	 */
+	btrfs_run_delayed_iput(fs_info, inode);
+
+	btrfs_i_size_write(dir, dir->vfs_inode.i_size - name->len * 2);
+	inode_inc_iversion(&inode->vfs_inode);
+	inode_set_ctime_current(&inode->vfs_inode);
+	inode_inc_iversion(&dir->vfs_inode);
+	update_time_after_link_or_unlink(dir);
+
+	return btrfs_update_inode(trans, dir);
+}
+
+int btrfs_unlink_inode(struct btrfs_trans_handle *trans,
+		       struct btrfs_inode *dir, struct btrfs_inode *inode,
+		       const struct fscrypt_str *name)
+{
+	int ret;
+
+	ret = __btrfs_unlink_inode(trans, dir, inode, name, NULL);
+	if (!ret) {
+		drop_nlink(&inode->vfs_inode);
+		ret = btrfs_update_inode(trans, inode);
+	}
+	return ret;
+}
+
+/*
+ * helper to start transaction for unlink and rmdir.
+ *
+ * unlink and rmdir are special in btrfs, they do not always free space, so
+ * if we cannot make our reservations the normal way try and see if there is
+ * plenty of slack room in the global reserve to migrate, otherwise we cannot
+ * allow the unlink to occur.
+ */
+static struct btrfs_trans_handle *__unlink_start_trans(struct btrfs_inode *dir)
+{
+	struct btrfs_root *root = dir->root;
+
+	return btrfs_start_transaction_fallback_global_rsv(root,
+						   BTRFS_UNLINK_METADATA_UNITS);
+}
+
+static int btrfs_unlink(struct inode *dir, struct dentry *dentry)
+{
+	struct btrfs_trans_handle *trans;
+	struct inode *inode = d_inode(dentry);
+	int ret;
+	struct fscrypt_name fname;
+
+	ret = fscrypt_setup_filename(dir, &dentry->d_name, 1, &fname);
+	if (ret)
+		return ret;
+
+	/* This needs to handle no-key deletions later on */
+
+	trans = __unlink_start_trans(BTRFS_I(dir));
+	if (IS_ERR(trans)) {
+		ret = PTR_ERR(trans);
+		goto fscrypt_free;
+	}
+
+	btrfs_record_unlink_dir(trans, BTRFS_I(dir), BTRFS_I(d_inode(dentry)),
+				false);
+
+	ret = btrfs_unlink_inode(trans, BTRFS_I(dir), BTRFS_I(d_inode(dentry)),
+				 &fname.disk_name);
+	if (ret)
+		goto end_trans;
+
+	if (inode->i_nlink == 0) {
+		ret = btrfs_orphan_add(trans, BTRFS_I(inode));
+		if (ret)
+			goto end_trans;
+	}
+
+end_trans:
+	btrfs_end_transaction(trans);
+	btrfs_btree_balance_dirty(BTRFS_I(dir)->root->fs_info);
+fscrypt_free:
+	fscrypt_free_filename(&fname);
+	return ret;
+}
+
+static int btrfs_unlink_subvol(struct btrfs_trans_handle *trans,
+			       struct btrfs_inode *dir, struct dentry *dentry)
+{
+	struct btrfs_root *root = dir->root;
+	struct btrfs_inode *inode = BTRFS_I(d_inode(dentry));
+	BTRFS_PATH_AUTO_FREE(path);
+	struct extent_buffer *leaf;
+	struct btrfs_dir_item *di;
+	struct btrfs_key key;
+	u64 index;
+	int ret;
+	u64 objectid;
+	u64 dir_ino = btrfs_ino(dir);
+	struct fscrypt_name fname;
+
+	ret = fscrypt_setup_filename(&dir->vfs_inode, &dentry->d_name, 1, &fname);
+	if (ret)
+		return ret;
+
+	/* This needs to handle no-key deletions later on */
+
+	if (btrfs_ino(inode) == BTRFS_FIRST_FREE_OBJECTID) {
+		objectid = btrfs_root_id(inode->root);
+	} else if (btrfs_ino(inode) == BTRFS_EMPTY_SUBVOL_DIR_OBJECTID) {
+		objectid = inode->ref_root_id;
+	} else {
+		WARN_ON(1);
+		fscrypt_free_filename(&fname);
+		return -EINVAL;
+	}
+
+	path = btrfs_alloc_path();
+	if (!path) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	di = btrfs_lookup_dir_item(trans, root, path, dir_ino,
+				   &fname.disk_name, -1);
+	if (IS_ERR_OR_NULL(di)) {
+		ret = di ? PTR_ERR(di) : -ENOENT;
+		goto out;
+	}
+
+	leaf = path->nodes[0];
+	btrfs_dir_item_key_to_cpu(leaf, di, &key);
+	WARN_ON(key.type != BTRFS_ROOT_ITEM_KEY || key.objectid != objectid);
+	ret = btrfs_delete_one_dir_name(trans, root, path, di);
+	if (unlikely(ret)) {
+		btrfs_abort_transaction(trans, ret);
+		goto out;
+	}
+	btrfs_release_path(path);
+
+	/*
+	 * This is a placeholder inode for a subvolume we didn't have a
+	 * reference to at the time of the snapshot creation.  In the meantime
+	 * we could have renamed the real subvol link into our snapshot, so
+	 * depending on btrfs_del_root_ref to return -ENOENT here is incorrect.
+	 * Instead simply lookup the dir_index_item for this entry so we can
+	 * remove it.  Otherwise we know we have a ref to the root and we can
+	 * call btrfs_del_root_ref, and it _shouldn't_ fail.
+	 */
+	if (btrfs_ino(inode) == BTRFS_EMPTY_SUBVOL_DIR_OBJECTID) {
+		di = btrfs_search_dir_index_item(root, path, dir_ino, &fname.disk_name);
+		if (IS_ERR(di)) {
+			ret = PTR_ERR(di);
+			btrfs_abort_transaction(trans, ret);
+			goto out;
+		}
+
+		leaf = path->nodes[0];
+		btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
+		index = key.offset;
+		btrfs_release_path(path);
+	} else {
+		ret = btrfs_del_root_ref(trans, objectid,
+					 btrfs_root_id(root), dir_ino,
+					 &index, &fname.disk_name);
+		if (unlikely(ret)) {
+			btrfs_abort_transaction(trans, ret);
+			goto out;
+		}
+	}
+
+	ret = btrfs_delete_delayed_dir_index(trans, dir, index);
+	if (unlikely(ret)) {
+		btrfs_abort_transaction(trans, ret);
+		goto out;
+	}
+
+	btrfs_i_size_write(dir, dir->vfs_inode.i_size - fname.disk_name.len * 2);
+	inode_inc_iversion(&dir->vfs_inode);
+	inode_set_mtime_to_ts(&dir->vfs_inode, inode_set_ctime_current(&dir->vfs_inode));
+	ret = btrfs_update_inode_fallback(trans, dir);
+	if (ret)
+		btrfs_abort_transaction(trans, ret);
+out:
+	fscrypt_free_filename(&fname);
+	return ret;
+}
+
+/*
+ * Helper to check if the subvolume references other subvolumes or if it's
+ * default.
+ */
+static noinline int may_destroy_subvol(struct btrfs_root *root)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	BTRFS_PATH_AUTO_FREE(path);
+	struct btrfs_dir_item *di;
+	struct btrfs_key key;
+	struct fscrypt_str name = FSTR_INIT("default", 7);
+	u64 dir_id;
+	int ret;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	/* Make sure this root isn't set as the default subvol */
+	dir_id = btrfs_super_root_dir(fs_info->super_copy);
+	di = btrfs_lookup_dir_item(NULL, fs_info->tree_root, path,
+				   dir_id, &name, 0);
+	if (!IS_ERR_OR_NULL(di)) {
+		btrfs_dir_item_key_to_cpu(path->nodes[0], di, &key);
+		if (key.objectid == btrfs_root_id(root)) {
+			ret = -EPERM;
+			btrfs_err(fs_info,
+				  "deleting default subvolume %llu is not allowed",
+				  key.objectid);
+			return ret;
+		}
+		btrfs_release_path(path);
+	}
+
+	key.objectid = btrfs_root_id(root);
+	key.type = BTRFS_ROOT_REF_KEY;
+	key.offset = (u64)-1;
+
+	ret = btrfs_search_slot(NULL, fs_info->tree_root, &key, path, 0, 0);
+	if (ret < 0)
+		return ret;
+	if (unlikely(ret == 0)) {
+		/*
+		 * Key with offset -1 found, there would have to exist a root
+		 * with such id, but this is out of valid range.
+		 */
+		return -EUCLEAN;
+	}
+
+	ret = 0;
+	if (path->slots[0] > 0) {
+		path->slots[0]--;
+		btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
+		if (key.objectid == btrfs_root_id(root) && key.type == BTRFS_ROOT_REF_KEY)
+			ret = -ENOTEMPTY;
+	}
+
+	return ret;
+}
+
+/* Delete all dentries for inodes belonging to the root */
+static void btrfs_prune_dentries(struct btrfs_root *root)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_inode *inode;
+	u64 min_ino = 0;
+
+	if (!BTRFS_FS_ERROR(fs_info))
+		WARN_ON(btrfs_root_refs(&root->root_item) != 0);
+
+	inode = btrfs_find_first_inode(root, min_ino);
+	while (inode) {
+		if (icount_read_once(&inode->vfs_inode) > 1)
+			d_prune_aliases(&inode->vfs_inode);
+
+		min_ino = btrfs_ino(inode) + 1;
+		/*
+		 * btrfs_drop_inode() will have it removed from the inode
+		 * cache when its usage count hits zero.
+		 */
+		iput(&inode->vfs_inode);
+		cond_resched();
+		inode = btrfs_find_first_inode(root, min_ino);
+	}
+}
+
+int btrfs_delete_subvolume(struct btrfs_inode *dir, struct dentry *dentry)
+{
+	struct btrfs_root *root = dir->root;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct inode *inode = d_inode(dentry);
+	struct btrfs_root *dest = BTRFS_I(inode)->root;
+	struct btrfs_trans_handle *trans;
+	struct btrfs_block_rsv block_rsv;
+	u64 root_flags;
+	u64 qgroup_reserved = 0;
+	int ret;
+
+	down_write(&fs_info->subvol_sem);
+
+	/*
+	 * Don't allow to delete a subvolume with send in progress. This is
+	 * inside the inode lock so the error handling that has to drop the bit
+	 * again is not run concurrently.
+	 */
+	spin_lock(&dest->root_item_lock);
+	if (dest->send_in_progress) {
+		spin_unlock(&dest->root_item_lock);
+		btrfs_warn(fs_info,
+			   "attempt to delete subvolume %llu during send",
+			   btrfs_root_id(dest));
+		ret = -EPERM;
+		goto out_up_write;
+	}
+	if (atomic_read(&dest->nr_swapfiles)) {
+		spin_unlock(&dest->root_item_lock);
+		btrfs_warn(fs_info,
+			   "attempt to delete subvolume %llu with active swapfile",
+			   btrfs_root_id(dest));
+		ret = -EPERM;
+		goto out_up_write;
+	}
+	root_flags = btrfs_root_flags(&dest->root_item);
+	btrfs_set_root_flags(&dest->root_item,
+			     root_flags | BTRFS_ROOT_SUBVOL_DEAD);
+	spin_unlock(&dest->root_item_lock);
+
+	ret = may_destroy_subvol(dest);
+	if (ret)
+		goto out_undead;
+
+	btrfs_init_block_rsv(&block_rsv, BTRFS_BLOCK_RSV_TEMP);
+	/*
+	 * One for dir inode,
+	 * two for dir entries,
+	 * two for root ref/backref.
+	 */
+	ret = btrfs_subvolume_reserve_metadata(root, &block_rsv, 5, true);
+	if (ret)
+		goto out_undead;
+	qgroup_reserved = block_rsv.qgroup_rsv_reserved;
+
+	trans = btrfs_start_transaction(root, 0);
+	if (IS_ERR(trans)) {
+		ret = PTR_ERR(trans);
+		goto out_release;
+	}
+	btrfs_qgroup_convert_reserved_meta(root, qgroup_reserved);
+	qgroup_reserved = 0;
+	trans->block_rsv = &block_rsv;
+	trans->bytes_reserved = block_rsv.size;
+
+	btrfs_record_snapshot_destroy(trans, dir);
+
+	ret = btrfs_unlink_subvol(trans, dir, dentry);
+	if (unlikely(ret)) {
+		btrfs_abort_transaction(trans, ret);
+		goto out_end_trans;
+	}
+
+	ret = btrfs_record_root_in_trans(trans, dest);
+	if (unlikely(ret)) {
+		btrfs_abort_transaction(trans, ret);
+		goto out_end_trans;
+	}
+
+	memset(&dest->root_item.drop_progress, 0,
+		sizeof(dest->root_item.drop_progress));
+	btrfs_set_root_drop_level(&dest->root_item, 0);
+	btrfs_set_root_refs(&dest->root_item, 0);
+
+	if (!test_and_set_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED, &dest->state)) {
+		ret = btrfs_insert_orphan_item(trans,
+					fs_info->tree_root,
+					btrfs_root_id(dest));
+		if (unlikely(ret)) {
+			btrfs_abort_transaction(trans, ret);
+			goto out_end_trans;
+		}
+	}
+
+	ret = btrfs_uuid_tree_remove(trans, dest->root_item.uuid,
+				     BTRFS_UUID_KEY_SUBVOL, btrfs_root_id(dest));
+	if (unlikely(ret && ret != -ENOENT)) {
+		btrfs_abort_transaction(trans, ret);
+		goto out_end_trans;
+	}
+	if (!btrfs_is_empty_uuid(dest->root_item.received_uuid)) {
+		ret = btrfs_uuid_tree_remove(trans,
+					  dest->root_item.received_uuid,
+					  BTRFS_UUID_KEY_RECEIVED_SUBVOL,
+					  btrfs_root_id(dest));
+		if (unlikely(ret && ret != -ENOENT)) {
+			btrfs_abort_transaction(trans, ret);
+			goto out_end_trans;
+		}
+	}
+
+	free_anon_bdev(dest->anon_dev);
+	dest->anon_dev = 0;
+out_end_trans:
+	trans->block_rsv = NULL;
+	trans->bytes_reserved = 0;
+	ret = btrfs_end_transaction(trans);
+	inode->i_flags |= S_DEAD;
+out_release:
+	btrfs_block_rsv_release(fs_info, &block_rsv, (u64)-1, NULL);
+	if (qgroup_reserved)
+		btrfs_qgroup_free_meta_prealloc(root, qgroup_reserved);
+out_undead:
+	if (ret) {
+		spin_lock(&dest->root_item_lock);
+		root_flags = btrfs_root_flags(&dest->root_item);
+		btrfs_set_root_flags(&dest->root_item,
+				root_flags & ~BTRFS_ROOT_SUBVOL_DEAD);
+		spin_unlock(&dest->root_item_lock);
+	}
+out_up_write:
+	up_write(&fs_info->subvol_sem);
+	if (!ret) {
+		d_invalidate(dentry);
+		btrfs_prune_dentries(dest);
+		ASSERT(dest->send_in_progress == 0);
+	}
+
+	return ret;
+}
+
+static int btrfs_rmdir(struct inode *vfs_dir, struct dentry *dentry)
+{
+	struct btrfs_inode *dir = BTRFS_I(vfs_dir);
+	struct btrfs_inode *inode = BTRFS_I(d_inode(dentry));
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+	int ret = 0;
+	struct btrfs_trans_handle *trans;
+	struct fscrypt_name fname;
+
+	if (inode->vfs_inode.i_size > BTRFS_EMPTY_DIR_SIZE)
+		return -ENOTEMPTY;
+	if (btrfs_ino(inode) == BTRFS_FIRST_FREE_OBJECTID) {
+		if (unlikely(btrfs_fs_incompat(fs_info, EXTENT_TREE_V2))) {
+			btrfs_err(fs_info,
+			"extent tree v2 doesn't support snapshot deletion yet");
+			return -EOPNOTSUPP;
+		}
+		return btrfs_delete_subvolume(dir, dentry);
+	}
+
+	ret = fscrypt_setup_filename(vfs_dir, &dentry->d_name, 1, &fname);
+	if (ret)
+		return ret;
+
+	/* This needs to handle no-key deletions later on */
+
+	trans = __unlink_start_trans(dir);
+	if (IS_ERR(trans)) {
+		ret = PTR_ERR(trans);
+		goto out_notrans;
+	}
+
+	/*
+	 * Propagate the last_unlink_trans value of the deleted dir to its
+	 * parent directory. This is to prevent an unrecoverable log tree in the
+	 * case we do something like this:
+	 * 1) create dir foo
+	 * 2) create snapshot under dir foo
+	 * 3) delete the snapshot
+	 * 4) rmdir foo
+	 * 5) mkdir foo
+	 * 6) fsync foo or some file inside foo
+	 *
+	 * This is because we can't unlink other roots when replaying the dir
+	 * deletes for directory foo.
+	 */
+	if (inode->last_unlink_trans >= trans->transid)
+		btrfs_record_snapshot_destroy(trans, dir);
+
+	if (unlikely(btrfs_ino(inode) == BTRFS_EMPTY_SUBVOL_DIR_OBJECTID)) {
+		ret = btrfs_unlink_subvol(trans, dir, dentry);
+		goto out;
+	}
+
+	ret = btrfs_orphan_add(trans, inode);
+	if (ret)
+		goto out;
+
+	btrfs_record_unlink_dir(trans, dir, inode, false);
+
+	/* now the directory is empty */
+	ret = btrfs_unlink_inode(trans, dir, inode, &fname.disk_name);
+	if (!ret)
+		btrfs_i_size_write(inode, 0);
+out:
+	btrfs_end_transaction(trans);
+out_notrans:
+	btrfs_btree_balance_dirty(fs_info);
+	fscrypt_free_filename(&fname);
+
+	return ret;
+}
+
+static bool is_inside_block(u64 bytenr, u64 blockstart, u32 blocksize)
+{
+	ASSERT(IS_ALIGNED(blockstart, blocksize), "blockstart=%llu blocksize=%u",
+		blockstart, blocksize);
+
+	if (blockstart <= bytenr && bytenr <= blockstart + blocksize - 1)
+		return true;
+	return false;
+}
+
+static int truncate_block_zero_beyond_eof(struct btrfs_inode *inode, u64 start)
+{
+	const pgoff_t index = (start >> PAGE_SHIFT);
+	struct address_space *mapping = inode->vfs_inode.i_mapping;
+	struct folio *folio;
+	u64 zero_start;
+	u64 zero_end;
+	int ret = 0;
+
+again:
+	folio = filemap_lock_folio(mapping, index);
+	/* No folio present. */
+	if (IS_ERR(folio))
+		return 0;
+
+	if (!folio_test_uptodate(folio)) {
+		ret = btrfs_read_folio(NULL, folio);
+		folio_lock(folio);
+		if (folio->mapping != mapping) {
+			folio_unlock(folio);
+			folio_put(folio);
+			goto again;
+		}
+		if (unlikely(!folio_test_uptodate(folio))) {
+			ret = -EIO;
+			goto out_unlock;
+		}
+	}
+	folio_wait_writeback(folio);
+
+	/*
+	 * We do not need to lock extents nor wait for OE, as it's already
+	 * beyond EOF.
+	 */
+
+	zero_start = max_t(u64, folio_pos(folio), start);
+	zero_end = folio_next_pos(folio);
+	folio_zero_range(folio, zero_start - folio_pos(folio),
+			 zero_end - zero_start);
+
+out_unlock:
+	folio_unlock(folio);
+	folio_put(folio);
+	return ret;
+}
+
+/*
+ * Handle the truncation of a fs block.
+ *
+ * @inode  - inode that we're zeroing
+ * @offset - the file offset of the block to truncate
+ *           The value must be inside [@start, @end], and the function will do
+ *           extra checks if the block that covers @offset needs to be zeroed.
+ * @start  - the start file offset of the range we want to zero
+ * @end    - the end (inclusive) file offset of the range we want to zero.
+ *
+ * If the range is not block aligned, read out the folio that covers @offset,
+ * and if needed zero blocks that are inside the folio and covered by [@start, @end).
+ * If @start or @end + 1 lands inside a block, that block will be marked dirty
+ * for writeback.
+ *
+ * This is utilized by hole punch, zero range, file expansion.
+ */
+int btrfs_truncate_block(struct btrfs_inode *inode, u64 offset, u64 start, u64 end)
+{
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+	struct address_space *mapping = inode->vfs_inode.i_mapping;
+	struct extent_io_tree *io_tree = &inode->io_tree;
+	struct btrfs_ordered_extent *ordered;
+	struct extent_state *cached_state = NULL;
+	struct extent_changeset *data_reserved = NULL;
+	bool only_release_metadata = false;
+	u32 blocksize = fs_info->sectorsize;
+	pgoff_t index = (offset >> PAGE_SHIFT);
+	struct folio *folio;
+	gfp_t mask = btrfs_alloc_write_mask(mapping);
+	int ret = 0;
+	const bool in_head_block = is_inside_block(offset, round_down(start, blocksize),
+						   blocksize);
+	const bool in_tail_block = is_inside_block(offset, round_down(end, blocksize),
+						   blocksize);
+	bool need_truncate_head = false;
+	bool need_truncate_tail = false;
+	u64 zero_start;
+	u64 zero_end;
+	u64 block_start;
+	u64 block_end;
+
+	/* @offset should be inside the range. */
+	ASSERT(start <= offset && offset <= end, "offset=%llu start=%llu end=%llu",
+	       offset, start, end);
+
+	/* The range is aligned at both ends. */
+	if (IS_ALIGNED(start, blocksize) && IS_ALIGNED(end + 1, blocksize)) {
+		/*
+		 * For block size < page size case, we may have polluted blocks
+		 * beyond EOF. So we also need to zero them out.
+		 */
+		if (end == (u64)-1 && blocksize < PAGE_SIZE)
+			ret = truncate_block_zero_beyond_eof(inode, start);
+		goto out;
+	}
+
+	/*
+	 * @offset may not be inside the head nor tail block. In that case we
+	 * don't need to do anything.
+	 */
+	if (!in_head_block && !in_tail_block)
+		goto out;
+
+	/*
+	 * Skip the truncation if the range in the target block is already aligned.
+	 * The seemingly complex check will also handle the same block case.
+	 */
+	if (in_head_block && !IS_ALIGNED(start, blocksize))
+		need_truncate_head = true;
+	if (in_tail_block && !IS_ALIGNED(end + 1, blocksize))
+		need_truncate_tail = true;
+	if (!need_truncate_head && !need_truncate_tail)
+		goto out;
+
+	block_start = round_down(offset, blocksize);
+	block_end = block_start + blocksize - 1;
+
+	ret = btrfs_check_data_free_space(inode, &data_reserved, block_start,
+					  blocksize, false);
+	if (ret < 0) {
+		size_t write_bytes = blocksize;
+
+		if (btrfs_check_nocow_lock(inode, block_start, &write_bytes, false) > 0) {
+			/* For nocow case, no need to reserve data space. */
+			ASSERT(write_bytes == blocksize, "write_bytes=%zu blocksize=%u",
+			       write_bytes, blocksize);
+			only_release_metadata = true;
+		} else {
+			goto out;
+		}
+	}
+	ret = btrfs_delalloc_reserve_metadata(inode, blocksize, blocksize, false);
+	if (ret < 0) {
+		if (!only_release_metadata)
+			btrfs_free_reserved_data_space(inode, data_reserved,
+						       block_start, blocksize);
+		goto out;
+	}
+again:
+	folio = __filemap_get_folio(mapping, index,
+				    FGP_LOCK | FGP_ACCESSED | FGP_CREAT, mask);
+	if (IS_ERR(folio)) {
+		if (only_release_metadata)
+			btrfs_delalloc_release_metadata(inode, blocksize, true);
+		else
+			btrfs_delalloc_release_space(inode, data_reserved,
+						     block_start, blocksize, true);
+		btrfs_delalloc_release_extents(inode, blocksize);
+		ret = PTR_ERR(folio);
+		goto out;
+	}
+
+	if (!folio_test_uptodate(folio)) {
+		ret = btrfs_read_folio(NULL, folio);
+		folio_lock(folio);
+		if (folio->mapping != mapping) {
+			folio_unlock(folio);
+			folio_put(folio);
+			goto again;
+		}
+		if (unlikely(!folio_test_uptodate(folio))) {
+			ret = -EIO;
+			goto out_unlock;
+		}
+	}
+
+	/*
+	 * We unlock the page after the io is completed and then re-lock it
+	 * above.  release_folio() could have come in between that and cleared
+	 * folio private, but left the page in the mapping.  Set the page mapped
+	 * here to make sure it's properly set for the subpage stuff.
+	 */
+	ret = set_folio_extent_mapped(folio);
+	if (ret < 0)
+		goto out_unlock;
+
+	folio_wait_writeback(folio);
+
+	btrfs_lock_extent(io_tree, block_start, block_end, &cached_state);
+
+	ordered = btrfs_lookup_ordered_extent(inode, block_start);
+	if (ordered) {
+		btrfs_unlock_extent(io_tree, block_start, block_end, &cached_state);
+		folio_unlock(folio);
+		folio_put(folio);
+		btrfs_start_ordered_extent(ordered);
+		btrfs_put_ordered_extent(ordered);
+		goto again;
+	}
+
+	ret = btrfs_reset_extent_delalloc(inode, block_start, block_end, 0, &cached_state);
+	if (ret) {
+		btrfs_unlock_extent(io_tree, block_start, block_end, &cached_state);
+		goto out_unlock;
+	}
+
+	if (end == (u64)-1) {
+		/*
+		 * We're truncating beyond EOF, the remaining blocks normally are
+		 * already holes thus no need to zero again, but it's possible for
+		 * fs block size < page size cases to have memory mapped writes
+		 * to pollute ranges beyond EOF.
+		 *
+		 * In that case although such polluted blocks beyond EOF will
+		 * not reach disk, it still affects our page caches.
+		 */
+		zero_start = max_t(u64, folio_pos(folio), start);
+		zero_end = min_t(u64, folio_next_pos(folio) - 1, end);
+	} else {
+		zero_start = max_t(u64, block_start, start);
+		zero_end = min_t(u64, block_end, end);
+	}
+	folio_zero_range(folio, zero_start - folio_pos(folio),
+			 zero_end - zero_start + 1);
+
+	btrfs_folio_set_dirty(fs_info, folio, block_start,
+			      block_end + 1 - block_start);
+
+	if (only_release_metadata)
+		btrfs_set_extent_bit(&inode->io_tree, block_start, block_end,
+				     EXTENT_NORESERVE, &cached_state);
+
+	btrfs_unlock_extent(io_tree, block_start, block_end, &cached_state);
+
+out_unlock:
+	if (ret) {
+		if (only_release_metadata)
+			btrfs_delalloc_release_metadata(inode, blocksize, true);
+		else
+			btrfs_delalloc_release_space(inode, data_reserved,
+					block_start, blocksize, true);
+	}
+	btrfs_delalloc_release_extents(inode, blocksize);
+	folio_unlock(folio);
+	folio_put(folio);
+out:
+	if (only_release_metadata)
+		btrfs_check_nocow_unlock(inode);
+	extent_changeset_free(data_reserved);
+	return ret;
+}
+
+static int maybe_insert_hole(struct btrfs_inode *inode, u64 offset, u64 len)
+{
+	struct btrfs_root *root = inode->root;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_trans_handle *trans;
+	struct btrfs_drop_extents_args drop_args = { 0 };
+	int ret;
+
+	/*
+	 * If NO_HOLES is enabled, we don't need to do anything.
+	 * Later, up in the call chain, either btrfs_set_inode_last_sub_trans()
+	 * or btrfs_update_inode() will be called, which guarantee that the next
+	 * fsync will know this inode was changed and needs to be logged.
+	 */
+	if (btrfs_fs_incompat(fs_info, NO_HOLES))
+		return 0;
+
+	/*
+	 * 1 - for the one we're dropping
+	 * 1 - for the one we're adding
+	 * 1 - for updating the inode.
+	 */
+	trans = btrfs_start_transaction(root, 3);
+	if (IS_ERR(trans))
+		return PTR_ERR(trans);
+
+	drop_args.start = offset;
+	drop_args.end = offset + len;
+	drop_args.drop_cache = true;
+
+	ret = btrfs_drop_extents(trans, root, inode, &drop_args);
+	if (unlikely(ret)) {
+		btrfs_abort_transaction(trans, ret);
+		btrfs_end_transaction(trans);
+		return ret;
+	}
+
+	ret = btrfs_insert_hole_extent(trans, root, btrfs_ino(inode), offset, len);
+	if (ret) {
+		btrfs_abort_transaction(trans, ret);
+	} else {
+		btrfs_update_inode_bytes(inode, 0, drop_args.bytes_found);
+		btrfs_update_inode(trans, inode);
+	}
+	btrfs_end_transaction(trans);
+	return ret;
+}
+
+/*
+ * This function puts in dummy file extents for the area we're creating a hole
+ * for.  So if we are truncating this file to a larger size we need to insert
+ * these file extents so that btrfs_get_extent will return a EXTENT_MAP_HOLE for
+ * the range between oldsize and size
+ */
+int btrfs_cont_expand(struct btrfs_inode *inode, loff_t oldsize, loff_t size)
+{
+	struct btrfs_root *root = inode->root;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct extent_io_tree *io_tree = &inode->io_tree;
+	struct extent_map *em = NULL;
+	struct extent_state *cached_state = NULL;
+	u64 hole_start = ALIGN(oldsize, fs_info->sectorsize);
+	u64 block_end = ALIGN(size, fs_info->sectorsize);
+	u64 last_byte;
+	u64 cur_offset;
+	u64 hole_size;
+	int ret = 0;
+
+	/*
+	 * If our size started in the middle of a block we need to zero out the
+	 * rest of the block before we expand the i_size, otherwise we could
+	 * expose stale data.
+	 */
+	ret = btrfs_truncate_block(inode, oldsize, oldsize, -1);
+	if (ret)
+		return ret;
+
+	if (size <= hole_start)
+		return 0;
+
+	btrfs_lock_and_flush_ordered_range(inode, hole_start, block_end - 1,
+					   &cached_state);
+	cur_offset = hole_start;
+	while (1) {
+		em = btrfs_get_extent(inode, NULL, cur_offset, block_end - cur_offset);
+		if (IS_ERR(em)) {
+			ret = PTR_ERR(em);
+			em = NULL;
+			break;
+		}
+		last_byte = min(btrfs_extent_map_end(em), block_end);
+		last_byte = ALIGN(last_byte, fs_info->sectorsize);
+		hole_size = last_byte - cur_offset;
+
+		if (!(em->flags & EXTENT_FLAG_PREALLOC)) {
+			struct extent_map *hole_em;
+
+			ret = maybe_insert_hole(inode, cur_offset, hole_size);
+			if (ret)
+				break;
+
+			ret = btrfs_inode_set_file_extent_range(inode,
+							cur_offset, hole_size);
+			if (ret)
+				break;
+
+			hole_em = btrfs_alloc_extent_map();
+			if (!hole_em) {
+				btrfs_drop_extent_map_range(inode, cur_offset,
+						    cur_offset + hole_size - 1,
+						    false);
+				btrfs_set_inode_full_sync(inode);
+				goto next;
+			}
+			hole_em->start = cur_offset;
+			hole_em->len = hole_size;
+
+			hole_em->disk_bytenr = EXTENT_MAP_HOLE;
+			hole_em->disk_num_bytes = 0;
+			hole_em->ram_bytes = hole_size;
+			hole_em->generation = btrfs_get_fs_generation(fs_info);
+
+			ret = btrfs_replace_extent_map_range(inode, hole_em, true);
+			btrfs_free_extent_map(hole_em);
+		} else {
+			ret = btrfs_inode_set_file_extent_range(inode,
+							cur_offset, hole_size);
+			if (ret)
+				break;
+		}
+next:
+		btrfs_free_extent_map(em);
+		em = NULL;
+		cur_offset = last_byte;
+		if (cur_offset >= block_end)
+			break;
+	}
+	btrfs_free_extent_map(em);
+	btrfs_unlock_extent(io_tree, hole_start, block_end - 1, &cached_state);
+	return ret;
+}
+
+static int btrfs_setsize(struct inode *inode, struct iattr *attr)
+{
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	struct btrfs_trans_handle *trans;
+	loff_t oldsize = i_size_read(inode);
+	loff_t newsize = attr->ia_size;
+	int mask = attr->ia_valid;
+	int ret;
+
+	/*
+	 * The regular truncate() case without ATTR_CTIME and ATTR_MTIME is a
+	 * special case where we need to update the times despite not having
+	 * these flags set.  For all other operations the VFS set these flags
+	 * explicitly if it wants a timestamp update.
+	 */
+	if (newsize != oldsize) {
+		inode_inc_iversion(inode);
+		if (!(mask & (ATTR_CTIME | ATTR_MTIME))) {
+			inode_set_mtime_to_ts(inode,
+					      inode_set_ctime_current(inode));
+		}
+	}
+
+	if (newsize > oldsize) {
+		/*
+		 * Don't do an expanding truncate while snapshotting is ongoing.
+		 * This is to ensure the snapshot captures a fully consistent
+		 * state of this file - if the snapshot captures this expanding
+		 * truncation, it must capture all writes that happened before
+		 * this truncation.
+		 */
+		btrfs_drew_write_lock(&root->snapshot_lock);
+		ret = btrfs_cont_expand(BTRFS_I(inode), oldsize, newsize);
+		if (ret) {
+			btrfs_drew_write_unlock(&root->snapshot_lock);
+			return ret;
+		}
+
+		trans = btrfs_start_transaction(root, 1);
+		if (IS_ERR(trans)) {
+			btrfs_drew_write_unlock(&root->snapshot_lock);
+			return PTR_ERR(trans);
+		}
+
+		i_size_write(inode, newsize);
+		btrfs_inode_safe_disk_i_size_write(BTRFS_I(inode), 0);
+		pagecache_isize_extended(inode, oldsize, newsize);
+		ret = btrfs_update_inode(trans, BTRFS_I(inode));
+		btrfs_drew_write_unlock(&root->snapshot_lock);
+		btrfs_end_transaction(trans);
+	} else {
+		struct btrfs_fs_info *fs_info = inode_to_fs_info(inode);
+
+		if (btrfs_is_zoned(fs_info)) {
+			ret = btrfs_wait_ordered_range(BTRFS_I(inode),
+					ALIGN(newsize, fs_info->sectorsize),
+					(u64)-1);
+			if (ret)
+				return ret;
+		}
+
+		/*
+		 * We're truncating a file that used to have good data down to
+		 * zero. Make sure any new writes to the file get on disk
+		 * on close.
+		 */
+		if (newsize == 0 && oldsize != 0)
+			set_bit(BTRFS_INODE_FLUSH_ON_CLOSE,
+				&BTRFS_I(inode)->runtime_flags);
+
+		truncate_setsize(inode, newsize);
+
+		inode_dio_wait(inode);
+
+		ret = btrfs_truncate(BTRFS_I(inode), newsize == oldsize);
+		if (ret && inode->i_nlink) {
+			int ret2;
+
+			/*
+			 * Truncate failed, so fix up the in-memory size. We
+			 * adjusted disk_i_size down as we removed extents, so
+			 * wait for disk_i_size to be stable and then update the
+			 * in-memory size to match.
+			 */
+			ret2 = btrfs_wait_ordered_range(BTRFS_I(inode), 0, (u64)-1);
+			if (ret2)
+				return ret2;
+			i_size_write(inode, BTRFS_I(inode)->disk_i_size);
+		}
+	}
+
+	return ret;
+}
+
+static int btrfs_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
+			 struct iattr *attr)
+{
+	struct inode *inode = d_inode(dentry);
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	int ret;
+
+	if (btrfs_root_readonly(root))
+		return -EROFS;
+
+	ret = setattr_prepare(idmap, dentry, attr);
+	if (ret)
+		return ret;
+
+	if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) {
+		ret = btrfs_setsize(inode, attr);
+		if (ret)
+			return ret;
+	}
+
+	if (attr->ia_valid) {
+		setattr_copy(idmap, inode, attr);
+		inode_inc_iversion(inode);
+		ret = btrfs_dirty_inode(BTRFS_I(inode));
+
+		if (!ret && attr->ia_valid & ATTR_MODE)
+			ret = posix_acl_chmod(idmap, dentry, inode->i_mode);
+	}
+
+	return ret;
+}
+
+/*
+ * While truncating the inode pages during eviction, we get the VFS
+ * calling btrfs_invalidate_folio() against each folio of the inode. This
+ * is slow because the calls to btrfs_invalidate_folio() result in a
+ * huge amount of calls to lock_extent() and clear_extent_bit(),
+ * which keep merging and splitting extent_state structures over and over,
+ * wasting lots of time.
+ *
+ * Therefore if the inode is being evicted, let btrfs_invalidate_folio()
+ * skip all those expensive operations on a per folio basis and do only
+ * the ordered io finishing, while we release here the extent_map and
+ * extent_state structures, without the excessive merging and splitting.
+ */
+static void evict_inode_truncate_pages(struct inode *inode)
+{
+	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
+	struct rb_node *node;
+
+	ASSERT(inode_state_read_once(inode) & I_FREEING);
+	truncate_inode_pages_final(&inode->i_data);
+
+	btrfs_drop_extent_map_range(BTRFS_I(inode), 0, (u64)-1, false);
+
+	/*
+	 * Keep looping until we have no more ranges in the io tree.
+	 * We can have ongoing bios started by readahead that have
+	 * their endio callback (extent_io.c:end_bio_extent_readpage)
+	 * still in progress (unlocked the pages in the bio but did not yet
+	 * unlocked the ranges in the io tree). Therefore this means some
+	 * ranges can still be locked and eviction started because before
+	 * submitting those bios, which are executed by a separate task (work
+	 * queue kthread), inode references (inode->i_count) were not taken
+	 * (which would be dropped in the end io callback of each bio).
+	 * Therefore here we effectively end up waiting for those bios and
+	 * anyone else holding locked ranges without having bumped the inode's
+	 * reference count - if we don't do it, when they access the inode's
+	 * io_tree to unlock a range it may be too late, leading to an
+	 * use-after-free issue.
+	 */
+	spin_lock(&io_tree->lock);
+	while (!RB_EMPTY_ROOT(&io_tree->state)) {
+		struct extent_state *state;
+		struct extent_state *cached_state = NULL;
+		u64 start;
+		u64 end;
+		unsigned state_flags;
+
+		node = rb_first(&io_tree->state);
+		state = rb_entry(node, struct extent_state, rb_node);
+		start = state->start;
+		end = state->end;
+		state_flags = state->state;
+		spin_unlock(&io_tree->lock);
+
+		btrfs_lock_extent(io_tree, start, end, &cached_state);
+
+		/*
+		 * If still has DELALLOC flag, the extent didn't reach disk,
+		 * and its reserved space won't be freed by delayed_ref.
+		 * So we need to free its reserved space here.
+		 * (Refer to comment in btrfs_invalidate_folio, case 2)
+		 *
+		 * Note, end is the bytenr of last byte, so we need + 1 here.
+		 */
+		if (state_flags & EXTENT_DELALLOC)
+			btrfs_qgroup_free_data(BTRFS_I(inode), NULL, start,
+					       end - start + 1, NULL);
+
+		btrfs_clear_extent_bit(io_tree, start, end,
+				       EXTENT_CLEAR_ALL_BITS | EXTENT_DO_ACCOUNTING,
+				       &cached_state);
+
+		cond_resched();
+		spin_lock(&io_tree->lock);
+	}
+	spin_unlock(&io_tree->lock);
+}
+
+static struct btrfs_trans_handle *evict_refill_and_join(struct btrfs_root *root,
+							struct btrfs_block_rsv *rsv)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_trans_handle *trans;
+	u64 delayed_refs_extra = btrfs_calc_delayed_ref_bytes(fs_info, 1);
+	int ret;
+
+	/*
+	 * Eviction should be taking place at some place safe because of our
+	 * delayed iputs.  However the normal flushing code will run delayed
+	 * iputs, so we cannot use FLUSH_ALL otherwise we'll deadlock.
+	 *
+	 * We reserve the delayed_refs_extra here again because we can't use
+	 * btrfs_start_transaction(root, 0) for the same deadlocky reason as
+	 * above.  We reserve our extra bit here because we generate a ton of
+	 * delayed refs activity by truncating.
+	 *
+	 * BTRFS_RESERVE_FLUSH_EVICT will steal from the global_rsv if it can,
+	 * if we fail to make this reservation we can re-try without the
+	 * delayed_refs_extra so we can make some forward progress.
+	 */
+	ret = btrfs_block_rsv_refill(fs_info, rsv, rsv->size + delayed_refs_extra,
+				     BTRFS_RESERVE_FLUSH_EVICT);
+	if (ret) {
+		ret = btrfs_block_rsv_refill(fs_info, rsv, rsv->size,
+					     BTRFS_RESERVE_FLUSH_EVICT);
+		if (ret) {
+			btrfs_warn(fs_info,
+				   "could not allocate space for delete; will truncate on mount");
+			return ERR_PTR(-ENOSPC);
+		}
+		delayed_refs_extra = 0;
+	}
+
+	trans = btrfs_join_transaction(root);
+	if (IS_ERR(trans))
+		return trans;
+
+	if (delayed_refs_extra) {
+		trans->block_rsv = &fs_info->trans_block_rsv;
+		trans->bytes_reserved = delayed_refs_extra;
+		btrfs_block_rsv_migrate(rsv, trans->block_rsv,
+					delayed_refs_extra, true);
+	}
+	return trans;
+}
+
+void btrfs_evict_inode(struct inode *inode)
+{
+	struct btrfs_fs_info *fs_info;
+	struct btrfs_trans_handle *trans;
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	struct btrfs_block_rsv rsv;
+	int ret;
+
+	trace_btrfs_inode_evict(inode);
+
+	if (!root)
+		goto clear_inode;
+
+	fs_info = inode_to_fs_info(inode);
+	evict_inode_truncate_pages(inode);
+
+	if (inode->i_nlink &&
+	    ((btrfs_root_refs(&root->root_item) != 0 &&
+	      btrfs_root_id(root) != BTRFS_ROOT_TREE_OBJECTID) ||
+	     btrfs_is_free_space_inode(BTRFS_I(inode))))
+		goto out;
+
+	if (is_bad_inode(inode))
+		goto out;
+
+	if (test_bit(BTRFS_FS_LOG_RECOVERING, &fs_info->flags))
+		goto out;
+
+	if (inode->i_nlink > 0) {
+		BUG_ON(btrfs_root_refs(&root->root_item) != 0 &&
+		       btrfs_root_id(root) != BTRFS_ROOT_TREE_OBJECTID);
+		goto out;
+	}
+
+	/*
+	 * This makes sure the inode item in tree is uptodate and the space for
+	 * the inode update is released.
+	 */
+	ret = btrfs_commit_inode_delayed_inode(BTRFS_I(inode));
+	if (ret)
+		goto out;
+
+	/*
+	 * This drops any pending insert or delete operations we have for this
+	 * inode.  We could have a delayed dir index deletion queued up, but
+	 * we're removing the inode completely so that'll be taken care of in
+	 * the truncate.
+	 */
+	btrfs_kill_delayed_inode_items(BTRFS_I(inode));
+
+	btrfs_init_metadata_block_rsv(fs_info, &rsv, BTRFS_BLOCK_RSV_TEMP);
+	rsv.size = btrfs_calc_metadata_size(fs_info, 1);
+	rsv.failfast = true;
+
+	btrfs_i_size_write(BTRFS_I(inode), 0);
+
+	while (1) {
+		struct btrfs_truncate_control control = {
+			.inode = BTRFS_I(inode),
+			.ino = btrfs_ino(BTRFS_I(inode)),
+			.new_size = 0,
+			.min_type = 0,
+		};
+
+		trans = evict_refill_and_join(root, &rsv);
+		if (IS_ERR(trans))
+			goto out_release;
+
+		trans->block_rsv = &rsv;
+
+		ret = btrfs_truncate_inode_items(trans, root, &control);
+		trans->block_rsv = &fs_info->trans_block_rsv;
+		btrfs_end_transaction(trans);
+		/*
+		 * We have not added new delayed items for our inode after we
+		 * have flushed its delayed items, so no need to throttle on
+		 * delayed items. However we have modified extent buffers.
+		 */
+		btrfs_btree_balance_dirty_nodelay(fs_info);
+		if (ret && ret != -ENOSPC && ret != -EAGAIN)
+			goto out_release;
+		else if (!ret)
+			break;
+	}
+
+	/*
+	 * Errors here aren't a big deal, it just means we leave orphan items in
+	 * the tree. They will be cleaned up on the next mount. If the inode
+	 * number gets reused, cleanup deletes the orphan item without doing
+	 * anything, and unlink reuses the existing orphan item.
+	 *
+	 * If it turns out that we are dropping too many of these, we might want
+	 * to add a mechanism for retrying these after a commit.
+	 */
+	trans = evict_refill_and_join(root, &rsv);
+	if (!IS_ERR(trans)) {
+		trans->block_rsv = &rsv;
+		btrfs_orphan_del(trans, BTRFS_I(inode));
+		trans->block_rsv = &fs_info->trans_block_rsv;
+		btrfs_end_transaction(trans);
+	}
+
+out_release:
+	btrfs_block_rsv_release(fs_info, &rsv, (u64)-1, NULL);
+out:
+	/*
+	 * If we didn't successfully delete, the orphan item will still be in
+	 * the tree and we'll retry on the next mount. Again, we might also want
+	 * to retry these periodically in the future.
+	 */
+	btrfs_remove_delayed_node(BTRFS_I(inode));
+clear_inode:
+	clear_inode(inode);
+}
+
+/*
+ * Return the key found in the dir entry in the location pointer, fill @type
+ * with BTRFS_FT_*, and return 0.
+ *
+ * If no dir entries were found, returns -ENOENT.
+ * If found a corrupted location in dir entry, returns -EUCLEAN.
+ */
+static int btrfs_inode_by_name(struct btrfs_inode *dir, struct dentry *dentry,
+			       struct btrfs_key *location, u8 *type)
+{
+	struct btrfs_dir_item *di;
+	BTRFS_PATH_AUTO_FREE(path);
+	struct btrfs_root *root = dir->root;
+	int ret = 0;
+	struct fscrypt_name fname;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	ret = fscrypt_setup_filename(&dir->vfs_inode, &dentry->d_name, 1, &fname);
+	if (ret < 0)
+		return ret;
+	/*
+	 * fscrypt_setup_filename() should never return a positive value, but
+	 * gcc on sparc/parisc thinks it can, so assert that doesn't happen.
+	 */
+	ASSERT(ret == 0);
+
+	/* This needs to handle no-key deletions later on */
+
+	di = btrfs_lookup_dir_item(NULL, root, path, btrfs_ino(dir),
+				   &fname.disk_name, 0);
+	if (IS_ERR_OR_NULL(di)) {
+		ret = di ? PTR_ERR(di) : -ENOENT;
+		goto out;
+	}
+
+	btrfs_dir_item_key_to_cpu(path->nodes[0], di, location);
+	if (unlikely(location->type != BTRFS_INODE_ITEM_KEY &&
+		     location->type != BTRFS_ROOT_ITEM_KEY)) {
+		ret = -EUCLEAN;
+		btrfs_warn(root->fs_info,
+"%s gets something invalid in DIR_ITEM (name %s, directory ino %llu, location " BTRFS_KEY_FMT ")",
+			   __func__, fname.disk_name.name, btrfs_ino(dir),
+			   BTRFS_KEY_FMT_VALUE(location));
+	}
+	if (!ret)
+		*type = btrfs_dir_ftype(path->nodes[0], di);
+out:
+	fscrypt_free_filename(&fname);
+	return ret;
+}
+
+/*
+ * when we hit a tree root in a directory, the btrfs part of the inode
+ * needs to be changed to reflect the root directory of the tree root.  This
+ * is kind of like crossing a mount point.
+ */
+static int fixup_tree_root_location(struct btrfs_fs_info *fs_info,
+				    struct btrfs_inode *dir,
+				    struct dentry *dentry,
+				    struct btrfs_key *location,
+				    struct btrfs_root **sub_root)
+{
+	BTRFS_PATH_AUTO_FREE(path);
+	struct btrfs_root *new_root;
+	struct btrfs_root_ref *ref;
+	struct extent_buffer *leaf;
+	struct btrfs_key key;
+	int ret;
+	int err = 0;
+	struct fscrypt_name fname;
+
+	ret = fscrypt_setup_filename(&dir->vfs_inode, &dentry->d_name, 0, &fname);
+	if (ret)
+		return ret;
+
+	path = btrfs_alloc_path();
+	if (!path) {
+		err = -ENOMEM;
+		goto out;
+	}
+
+	err = -ENOENT;
+	key.objectid = btrfs_root_id(dir->root);
+	key.type = BTRFS_ROOT_REF_KEY;
+	key.offset = location->objectid;
+
+	ret = btrfs_search_slot(NULL, fs_info->tree_root, &key, path, 0, 0);
+	if (ret) {
+		if (ret < 0)
+			err = ret;
+		goto out;
+	}
+
+	leaf = path->nodes[0];
+	ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref);
+	if (btrfs_root_ref_dirid(leaf, ref) != btrfs_ino(dir) ||
+	    btrfs_root_ref_name_len(leaf, ref) != fname.disk_name.len)
+		goto out;
+
+	ret = memcmp_extent_buffer(leaf, fname.disk_name.name,
+				   (unsigned long)(ref + 1), fname.disk_name.len);
+	if (ret)
+		goto out;
+
+	btrfs_release_path(path);
+
+	new_root = btrfs_get_fs_root(fs_info, location->objectid, true);
+	if (IS_ERR(new_root)) {
+		err = PTR_ERR(new_root);
+		goto out;
+	}
+
+	*sub_root = new_root;
+	location->objectid = btrfs_root_dirid(&new_root->root_item);
+	location->type = BTRFS_INODE_ITEM_KEY;
+	location->offset = 0;
+	err = 0;
+out:
+	fscrypt_free_filename(&fname);
+	return err;
+}
+
+
+
+static void btrfs_del_inode_from_root(struct btrfs_inode *inode)
+{
+	struct btrfs_root *root = inode->root;
+	struct btrfs_inode *entry;
+	bool empty = false;
+
+	xa_lock(&root->inodes);
+	/*
+	 * This btrfs_inode is being freed and has already been unhashed at this
+	 * point. It's possible that another btrfs_inode has already been
+	 * allocated for the same inode and inserted itself into the root, so
+	 * don't delete it in that case.
+	 *
+	 * Note that this shouldn't need to allocate memory, so the gfp flags
+	 * don't really matter.
+	 */
+	entry = __xa_cmpxchg(&root->inodes, btrfs_ino(inode), inode, NULL,
+			     GFP_ATOMIC);
+	if (entry == inode)
+		empty = xa_empty(&root->inodes);
+	xa_unlock(&root->inodes);
+
+	if (empty && btrfs_root_refs(&root->root_item) == 0) {
+		xa_lock(&root->inodes);
+		empty = xa_empty(&root->inodes);
+		xa_unlock(&root->inodes);
+		if (empty)
+			btrfs_add_dead_root(root);
+	}
+}
+
+
+static int btrfs_init_locked_inode(struct inode *inode, void *p)
+{
+	struct btrfs_iget_args *args = p;
+
+	btrfs_set_inode_number(BTRFS_I(inode), args->ino);
+	BTRFS_I(inode)->root = btrfs_grab_root(args->root);
+
+	if (args->root && args->root == args->root->fs_info->tree_root &&
+	    args->ino != BTRFS_BTREE_INODE_OBJECTID)
+		set_bit(BTRFS_INODE_FREE_SPACE_INODE,
+			&BTRFS_I(inode)->runtime_flags);
+	return 0;
+}
+
+static int btrfs_find_actor(struct inode *inode, void *opaque)
+{
+	struct btrfs_iget_args *args = opaque;
+
+	return args->ino == btrfs_ino(BTRFS_I(inode)) &&
+		args->root == BTRFS_I(inode)->root;
+}
+
+static struct btrfs_inode *btrfs_iget_locked(u64 ino, struct btrfs_root *root)
+{
+	struct inode *inode;
+	struct btrfs_iget_args args;
+	unsigned long hashval = btrfs_inode_hash(ino, root);
+
+	args.ino = ino;
+	args.root = root;
+
+	inode = iget5_locked_rcu(root->fs_info->sb, hashval, btrfs_find_actor,
+			     btrfs_init_locked_inode,
+			     (void *)&args);
+	if (!inode)
+		return NULL;
+	return BTRFS_I(inode);
+}
+
+/*
+ * Get an inode object given its inode number and corresponding root.  Path is
+ * preallocated to prevent recursing back to iget through allocator.
+ */
+struct btrfs_inode *btrfs_iget_path(u64 ino, struct btrfs_root *root,
+				    struct btrfs_path *path)
+{
+	struct btrfs_inode *inode;
+	int ret;
+
+	inode = btrfs_iget_locked(ino, root);
+	if (!inode)
+		return ERR_PTR(-ENOMEM);
+
+	if (!(inode_state_read_once(&inode->vfs_inode) & I_NEW))
+		return inode;
+
+	ret = btrfs_read_locked_inode(inode, path);
+	if (ret)
+		return ERR_PTR(ret);
+
+	unlock_new_inode(&inode->vfs_inode);
+	return inode;
+}
+
+/*
+ * Get an inode object given its inode number and corresponding root.
+ */
+struct btrfs_inode *btrfs_iget(u64 ino, struct btrfs_root *root)
+{
+	struct btrfs_inode *inode;
+	struct btrfs_path *path;
+	int ret;
+
+	inode = btrfs_iget_locked(ino, root);
+	if (!inode)
+		return ERR_PTR(-ENOMEM);
+
+	if (!(inode_state_read_once(&inode->vfs_inode) & I_NEW))
+		return inode;
+
+	path = btrfs_alloc_path();
+	if (!path) {
+		iget_failed(&inode->vfs_inode);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	ret = btrfs_read_locked_inode(inode, path);
+	btrfs_free_path(path);
+	if (ret)
+		return ERR_PTR(ret);
+
+	if (S_ISDIR(inode->vfs_inode.i_mode))
+		inode->vfs_inode.i_opflags |= IOP_FASTPERM_MAY_EXEC;
+	unlock_new_inode(&inode->vfs_inode);
+	return inode;
+}
+
+static struct btrfs_inode *new_simple_dir(struct inode *dir,
+					  struct btrfs_key *key,
+					  struct btrfs_root *root)
+{
+	struct timespec64 ts;
+	struct inode *vfs_inode;
+	struct btrfs_inode *inode;
+
+	vfs_inode = new_inode(dir->i_sb);
+	if (!vfs_inode)
+		return ERR_PTR(-ENOMEM);
+
+	inode = BTRFS_I(vfs_inode);
+	inode->root = btrfs_grab_root(root);
+	inode->ref_root_id = key->objectid;
+	set_bit(BTRFS_INODE_ROOT_STUB, &inode->runtime_flags);
+	set_bit(BTRFS_INODE_DUMMY, &inode->runtime_flags);
+
+	btrfs_set_inode_number(inode, BTRFS_EMPTY_SUBVOL_DIR_OBJECTID);
+	/*
+	 * We only need lookup, the rest is read-only and there's no inode
+	 * associated with the dentry
+	 */
+	vfs_inode->i_op = &simple_dir_inode_operations;
+	vfs_inode->i_opflags &= ~IOP_XATTR;
+	vfs_inode->i_fop = &simple_dir_operations;
+	vfs_inode->i_mode = S_IFDIR | S_IRUGO | S_IWUSR | S_IXUGO;
+
+	ts = inode_set_ctime_current(vfs_inode);
+	inode_set_mtime_to_ts(vfs_inode, ts);
+	inode_set_atime_to_ts(vfs_inode, inode_get_atime(dir));
+	inode->i_otime_sec = ts.tv_sec;
+	inode->i_otime_nsec = ts.tv_nsec;
+
+	vfs_inode->i_uid = dir->i_uid;
+	vfs_inode->i_gid = dir->i_gid;
+
+	return inode;
+}
+
+static_assert(BTRFS_FT_UNKNOWN == FT_UNKNOWN);
+static_assert(BTRFS_FT_REG_FILE == FT_REG_FILE);
+static_assert(BTRFS_FT_DIR == FT_DIR);
+static_assert(BTRFS_FT_CHRDEV == FT_CHRDEV);
+static_assert(BTRFS_FT_BLKDEV == FT_BLKDEV);
+static_assert(BTRFS_FT_FIFO == FT_FIFO);
+static_assert(BTRFS_FT_SOCK == FT_SOCK);
+static_assert(BTRFS_FT_SYMLINK == FT_SYMLINK);
+
+static inline u8 btrfs_inode_type(const struct btrfs_inode *inode)
+{
+	return fs_umode_to_ftype(inode->vfs_inode.i_mode);
+}
+
+struct inode *btrfs_lookup_dentry(struct inode *dir, struct dentry *dentry)
+{
+	struct btrfs_fs_info *fs_info = inode_to_fs_info(dir);
+	struct btrfs_inode *inode;
+	struct btrfs_root *root = BTRFS_I(dir)->root;
+	struct btrfs_root *sub_root = root;
+	struct btrfs_key location = { 0 };
+	u8 di_type = 0;
+	int ret = 0;
+
+	if (dentry->d_name.len > BTRFS_NAME_LEN)
+		return ERR_PTR(-ENAMETOOLONG);
+
+	ret = btrfs_inode_by_name(BTRFS_I(dir), dentry, &location, &di_type);
+	if (ret < 0)
+		return ERR_PTR(ret);
+
+	if (location.type == BTRFS_INODE_ITEM_KEY) {
+		inode = btrfs_iget(location.objectid, root);
+		if (IS_ERR(inode))
+			return ERR_CAST(inode);
+
+		/* Do extra check against inode mode with di_type */
+		if (unlikely(btrfs_inode_type(inode) != di_type)) {
+			btrfs_crit(fs_info,
+"inode mode mismatch with dir: inode mode=0%o btrfs type=%u dir type=%u",
+				  inode->vfs_inode.i_mode, btrfs_inode_type(inode),
+				  di_type);
+			iput(&inode->vfs_inode);
+			return ERR_PTR(-EUCLEAN);
+		}
+		return &inode->vfs_inode;
+	}
+
+	ret = fixup_tree_root_location(fs_info, BTRFS_I(dir), dentry,
+				       &location, &sub_root);
+	if (ret < 0) {
+		if (ret != -ENOENT)
+			inode = ERR_PTR(ret);
+		else
+			inode = new_simple_dir(dir, &location, root);
+	} else {
+		inode = btrfs_iget(location.objectid, sub_root);
+		btrfs_put_root(sub_root);
+
+		if (IS_ERR(inode))
+			return ERR_CAST(inode);
+
+		down_read(&fs_info->cleanup_work_sem);
+		if (!sb_rdonly(inode->vfs_inode.i_sb))
+			ret = btrfs_orphan_cleanup(sub_root);
+		up_read(&fs_info->cleanup_work_sem);
+		if (ret) {
+			iput(&inode->vfs_inode);
+			inode = ERR_PTR(ret);
+		}
+	}
+
+	if (IS_ERR(inode))
+		return ERR_CAST(inode);
+
+	return &inode->vfs_inode;
+}
+
+static int btrfs_dentry_delete(const struct dentry *dentry)
+{
+	struct btrfs_root *root;
+	struct inode *inode = d_inode(dentry);
+
+	if (!inode && !IS_ROOT(dentry))
+		inode = d_inode(dentry->d_parent);
+
+	if (inode) {
+		root = BTRFS_I(inode)->root;
+		if (btrfs_root_refs(&root->root_item) == 0)
+			return 1;
+
+		if (btrfs_ino(BTRFS_I(inode)) == BTRFS_EMPTY_SUBVOL_DIR_OBJECTID)
+			return 1;
+	}
+	return 0;
+}
+
+static struct dentry *btrfs_lookup(struct inode *dir, struct dentry *dentry,
+				   unsigned int flags)
+{
+	struct inode *inode = btrfs_lookup_dentry(dir, dentry);
+
+	if (inode == ERR_PTR(-ENOENT))
+		inode = NULL;
+	return d_splice_alias(inode, dentry);
+}
+
+/*
+ * Find the highest existing sequence number in a directory and then set the
+ * in-memory index_cnt variable to the first free sequence number.
+ */
+static int btrfs_set_inode_index_count(struct btrfs_inode *inode)
+{
+	struct btrfs_root *root = inode->root;
+	struct btrfs_key key, found_key;
+	BTRFS_PATH_AUTO_FREE(path);
+	struct extent_buffer *leaf;
+	int ret;
+
+	key.objectid = btrfs_ino(inode);
+	key.type = BTRFS_DIR_INDEX_KEY;
+	key.offset = (u64)-1;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+	if (ret < 0)
+		return ret;
+
+	if (unlikely(ret == 0)) {
+		/*
+		 * Key with offset -1 found, there would have to exist a dir
+		 * index item with such offset, but this is out of the valid
+		 * range.
+		 */
+		btrfs_err(root->fs_info,
+			  "unexpected exact match for DIR_INDEX key, inode %llu",
+			  btrfs_ino(inode));
+		return -EUCLEAN;
+	}
+
+	if (path->slots[0] == 0) {
+		inode->index_cnt = BTRFS_DIR_START_INDEX;
+		return 0;
+	}
+
+	path->slots[0]--;
+
+	leaf = path->nodes[0];
+	btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
+
+	if (found_key.objectid != btrfs_ino(inode) ||
+	    found_key.type != BTRFS_DIR_INDEX_KEY) {
+		inode->index_cnt = BTRFS_DIR_START_INDEX;
+		return 0;
+	}
+
+	inode->index_cnt = found_key.offset + 1;
+
+	return 0;
+}
+
+static int btrfs_get_dir_last_index(struct btrfs_inode *dir, u64 *index)
+{
+	int ret = 0;
+
+	btrfs_inode_lock(dir, 0);
+	if (dir->index_cnt == (u64)-1) {
+		ret = btrfs_inode_delayed_dir_index_count(dir);
+		if (ret) {
+			ret = btrfs_set_inode_index_count(dir);
+			if (ret)
+				goto out;
+		}
+	}
+
+	/* index_cnt is the index number of next new entry, so decrement it. */
+	*index = dir->index_cnt - 1;
+out:
+	btrfs_inode_unlock(dir, 0);
+
+	return ret;
+}
+
+/*
+ * All this infrastructure exists because dir_emit can fault, and we are holding
+ * the tree lock when doing readdir.  For now just allocate a buffer and copy
+ * our information into that, and then dir_emit from the buffer.  This is
+ * similar to what NFS does, only we don't keep the buffer around in pagecache
+ * because I'm afraid I'll mess that up.  Long term we need to make filldir do
+ * copy_to_user_inatomic so we don't have to worry about page faulting under the
+ * tree lock.
+ */
+static int btrfs_opendir(struct inode *inode, struct file *file)
+{
+	struct btrfs_file_private *private;
+	u64 last_index;
+	int ret;
+
+	ret = btrfs_get_dir_last_index(BTRFS_I(inode), &last_index);
+	if (ret)
+		return ret;
+
+	private = kzalloc_obj(struct btrfs_file_private);
+	if (!private)
+		return -ENOMEM;
+	private->last_index = last_index;
+	private->filldir_buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!private->filldir_buf) {
+		kfree(private);
+		return -ENOMEM;
+	}
+	file->private_data = private;
+	return 0;
+}
+
+static loff_t btrfs_dir_llseek(struct file *file, loff_t offset, int whence)
+{
+	struct btrfs_file_private *private = file->private_data;
+	int ret;
+
+	ret = btrfs_get_dir_last_index(BTRFS_I(file_inode(file)),
+				       &private->last_index);
+	if (ret)
+		return ret;
+
+	return generic_file_llseek(file, offset, whence);
+}
+
+struct dir_entry {
+	u64 ino;
+	u64 offset;
+	unsigned type;
+	int name_len;
+};
+
+static int btrfs_filldir(void *addr, int entries, struct dir_context *ctx)
+{
+	while (entries--) {
+		struct dir_entry *entry = addr;
+		char *name = (char *)(entry + 1);
+
+		ctx->pos = get_unaligned(&entry->offset);
+		if (!dir_emit(ctx, name, get_unaligned(&entry->name_len),
+					 get_unaligned(&entry->ino),
+					 get_unaligned(&entry->type)))
+			return 1;
+		addr += sizeof(struct dir_entry) +
+			get_unaligned(&entry->name_len);
+		ctx->pos++;
+	}
+	return 0;
+}
+
+static int btrfs_real_readdir(struct file *file, struct dir_context *ctx)
+{
+	struct inode *inode = file_inode(file);
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	struct btrfs_file_private *private = file->private_data;
+	struct btrfs_dir_item *di;
+	struct btrfs_key key;
+	struct btrfs_key found_key;
+	BTRFS_PATH_AUTO_FREE(path);
+	void *addr;
+	LIST_HEAD(ins_list);
+	LIST_HEAD(del_list);
+	int ret;
+	char *name_ptr;
+	int name_len;
+	int entries = 0;
+	int total_len = 0;
+	bool put = false;
+	struct btrfs_key location;
+
+	if (!dir_emit_dots(file, ctx))
+		return 0;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	addr = private->filldir_buf;
+	path->reada = READA_FORWARD;
+
+	put = btrfs_readdir_get_delayed_items(BTRFS_I(inode), private->last_index,
+					      &ins_list, &del_list);
+
+again:
+	key.type = BTRFS_DIR_INDEX_KEY;
+	key.offset = ctx->pos;
+	key.objectid = btrfs_ino(BTRFS_I(inode));
+
+	btrfs_for_each_slot(root, &key, &found_key, path, ret) {
+		struct dir_entry *entry;
+		struct extent_buffer *leaf = path->nodes[0];
+		u8 ftype;
+
+		if (found_key.objectid != key.objectid)
+			break;
+		if (found_key.type != BTRFS_DIR_INDEX_KEY)
+			break;
+		if (found_key.offset < ctx->pos)
+			continue;
+		if (found_key.offset > private->last_index)
+			break;
+		if (btrfs_should_delete_dir_index(&del_list, found_key.offset))
+			continue;
+		di = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_dir_item);
+		name_len = btrfs_dir_name_len(leaf, di);
+		if ((total_len + sizeof(struct dir_entry) + name_len) >=
+		    PAGE_SIZE) {
+			btrfs_release_path(path);
+			ret = btrfs_filldir(private->filldir_buf, entries, ctx);
+			if (ret)
+				goto nopos;
+			addr = private->filldir_buf;
+			entries = 0;
+			total_len = 0;
+			goto again;
+		}
+
+		ftype = btrfs_dir_flags_to_ftype(btrfs_dir_flags(leaf, di));
+		entry = addr;
+		name_ptr = (char *)(entry + 1);
+		read_extent_buffer(leaf, name_ptr,
+				   (unsigned long)(di + 1), name_len);
+		put_unaligned(name_len, &entry->name_len);
+		put_unaligned(fs_ftype_to_dtype(ftype), &entry->type);
+		btrfs_dir_item_key_to_cpu(leaf, di, &location);
+		put_unaligned(location.objectid, &entry->ino);
+		put_unaligned(found_key.offset, &entry->offset);
+		entries++;
+		addr += sizeof(struct dir_entry) + name_len;
+		total_len += sizeof(struct dir_entry) + name_len;
+	}
+	/* Catch error encountered during iteration */
+	if (ret < 0)
+		goto err;
+
+	btrfs_release_path(path);
+
+	ret = btrfs_filldir(private->filldir_buf, entries, ctx);
+	if (ret)
+		goto nopos;
+
+	if (btrfs_readdir_delayed_dir_index(ctx, &ins_list))
+		goto nopos;
+
+	/*
+	 * Stop new entries from being returned after we return the last
+	 * entry.
+	 *
+	 * New directory entries are assigned a strictly increasing
+	 * offset.  This means that new entries created during readdir
+	 * are *guaranteed* to be seen in the future by that readdir.
+	 * This has broken buggy programs which operate on names as
+	 * they're returned by readdir.  Until we reuse freed offsets
+	 * we have this hack to stop new entries from being returned
+	 * under the assumption that they'll never reach this huge
+	 * offset.
+	 *
+	 * This is being careful not to overflow 32bit loff_t unless the
+	 * last entry requires it because doing so has broken 32bit apps
+	 * in the past.
+	 */
+	if (ctx->pos >= INT_MAX)
+		ctx->pos = LLONG_MAX;
+	else
+		ctx->pos = INT_MAX;
+nopos:
+	ret = 0;
+err:
+	if (put)
+		btrfs_readdir_put_delayed_items(BTRFS_I(inode), &ins_list, &del_list);
+	return ret;
+}
+
+/*
+ * This is somewhat expensive, updating the tree every time the
+ * inode changes.  But, it is most likely to find the inode in cache.
+ * FIXME, needs more benchmarking...there are no reasons other than performance
+ * to keep or drop this code.
+ */
+static int btrfs_dirty_inode(struct btrfs_inode *inode)
+{
+	struct btrfs_root *root = inode->root;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_trans_handle *trans;
+	int ret;
+
+	if (test_bit(BTRFS_INODE_DUMMY, &inode->runtime_flags))
+		return 0;
+
+	trans = btrfs_join_transaction(root);
+	if (IS_ERR(trans))
+		return PTR_ERR(trans);
+
+	ret = btrfs_update_inode(trans, inode);
+	if (ret == -ENOSPC || ret == -EDQUOT) {
+		/* whoops, lets try again with the full transaction */
+		btrfs_end_transaction(trans);
+		trans = btrfs_start_transaction(root, 1);
+		if (IS_ERR(trans))
+			return PTR_ERR(trans);
+
+		ret = btrfs_update_inode(trans, inode);
+	}
+	btrfs_end_transaction(trans);
+	if (inode->delayed_node)
+		btrfs_balance_delayed_items(fs_info);
+
+	return ret;
+}
+
+/*
+ * We need our own ->update_time so that we can return error on ENOSPC for
+ * updating the inode in the case of file write and mmap writes.
+ */
+static int btrfs_update_time(struct inode *inode, enum fs_update_time type,
+		unsigned int flags)
+{
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	int dirty;
+
+	if (btrfs_root_readonly(root))
+		return -EROFS;
+	if (flags & IOCB_NOWAIT)
+		return -EAGAIN;
+
+	dirty = inode_update_time(inode, type, flags);
+	if (dirty <= 0)
+		return dirty;
+	return btrfs_dirty_inode(BTRFS_I(inode));
+}
+
+/*
+ * helper to find a free sequence number in a given directory.  This current
+ * code is very simple, later versions will do smarter things in the btree
+ */
+int btrfs_set_inode_index(struct btrfs_inode *dir, u64 *index)
+{
+	int ret = 0;
+
+	if (dir->index_cnt == (u64)-1) {
+		ret = btrfs_inode_delayed_dir_index_count(dir);
+		if (ret) {
+			ret = btrfs_set_inode_index_count(dir);
+			if (ret)
+				return ret;
+		}
+	}
+
+	*index = dir->index_cnt;
+	dir->index_cnt++;
+
+	return ret;
+}
+
+static int btrfs_insert_inode_locked(struct inode *inode)
+{
+	struct btrfs_iget_args args;
+
+	args.ino = btrfs_ino(BTRFS_I(inode));
+	args.root = BTRFS_I(inode)->root;
+
+	return insert_inode_locked4(inode,
+		   btrfs_inode_hash(inode->i_ino, BTRFS_I(inode)->root),
+		   btrfs_find_actor, &args);
+}
+
+int btrfs_new_inode_prepare(struct btrfs_new_inode_args *args,
+			    unsigned int *trans_num_items)
+{
+	struct inode *dir = args->dir;
+	struct inode *inode = args->inode;
+	int ret;
+
+	if (!args->orphan) {
+		ret = fscrypt_setup_filename(dir, &args->dentry->d_name, 0,
+					     &args->fname);
+		if (ret)
+			return ret;
+	}
+
+	ret = posix_acl_create(dir, &inode->i_mode, &args->default_acl, &args->acl);
+	if (ret) {
+		fscrypt_free_filename(&args->fname);
+		return ret;
+	}
+
+	/* 1 to add inode item */
+	*trans_num_items = 1;
+	/* 1 to add compression property */
+	if (BTRFS_I(dir)->prop_compress)
+		(*trans_num_items)++;
+	/* 1 to add default ACL xattr */
+	if (args->default_acl)
+		(*trans_num_items)++;
+	/* 1 to add access ACL xattr */
+	if (args->acl)
+		(*trans_num_items)++;
+#ifdef CONFIG_SECURITY
+	/* 1 to add LSM xattr */
+	if (dir->i_security)
+		(*trans_num_items)++;
+#endif
+	if (args->orphan) {
+		/* 1 to add orphan item */
+		(*trans_num_items)++;
+	} else {
+		/*
+		 * 1 to add dir item
+		 * 1 to add dir index
+		 * 1 to update parent inode item
+		 *
+		 * No need for 1 unit for the inode ref item because it is
+		 * inserted in a batch together with the inode item at
+		 * btrfs_create_new_inode().
+		 */
+		*trans_num_items += 3;
+	}
+	return 0;
+}
+
+void btrfs_new_inode_args_destroy(struct btrfs_new_inode_args *args)
+{
+	posix_acl_release(args->acl);
+	posix_acl_release(args->default_acl);
+	fscrypt_free_filename(&args->fname);
+}
+
+/*
+ * Inherit flags from the parent inode.
+ *
+ * Currently only the compression flags and the cow flags are inherited.
+ */
+static void btrfs_inherit_iflags(struct btrfs_inode *inode, struct btrfs_inode *dir)
+{
+	unsigned int flags;
+
+	flags = dir->flags;
+
+	if (flags & BTRFS_INODE_NOCOMPRESS) {
+		inode->flags &= ~BTRFS_INODE_COMPRESS;
+		inode->flags |= BTRFS_INODE_NOCOMPRESS;
+	} else if (flags & BTRFS_INODE_COMPRESS) {
+		inode->flags &= ~BTRFS_INODE_NOCOMPRESS;
+		inode->flags |= BTRFS_INODE_COMPRESS;
+	}
+
+	if (flags & BTRFS_INODE_NODATACOW) {
+		inode->flags |= BTRFS_INODE_NODATACOW;
+		if (S_ISREG(inode->vfs_inode.i_mode))
+			inode->flags |= BTRFS_INODE_NODATASUM;
+	}
+
+	btrfs_sync_inode_flags_to_i_flags(inode);
+}
+
+int btrfs_create_new_inode(struct btrfs_trans_handle *trans,
+			   struct btrfs_new_inode_args *args)
+{
+	struct timespec64 ts;
+	struct inode *dir = args->dir;
+	struct inode *inode = args->inode;
+	const struct fscrypt_str *name = args->orphan ? NULL : &args->fname.disk_name;
+	struct btrfs_fs_info *fs_info = inode_to_fs_info(dir);
+	struct btrfs_root *root;
+	struct btrfs_inode_item *inode_item;
+	struct btrfs_path *path;
+	u64 objectid;
+	struct btrfs_inode_ref *ref;
+	struct btrfs_key key[2];
+	u32 sizes[2];
+	struct btrfs_item_batch batch;
+	unsigned long ptr;
+	int ret;
+	bool xa_reserved = false;
+
+	if (!args->orphan && !args->subvol) {
+		/*
+		 * Before anything else, check if we can add the name to the
+		 * parent directory. We want to avoid a dir item overflow in
+		 * case we have an existing dir item due to existing name
+		 * hash collisions. We do this check here before we call
+		 * btrfs_add_link() down below so that we can avoid a
+		 * transaction abort (which could be exploited by malicious
+		 * users).
+		 *
+		 * For subvolumes we already do this in btrfs_mksubvol().
+		 */
+		ret = btrfs_check_dir_item_collision(BTRFS_I(dir)->root,
+						     btrfs_ino(BTRFS_I(dir)),
+						     name);
+		if (ret < 0)
+			return ret;
+	}
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	if (!args->subvol)
+		BTRFS_I(inode)->root = btrfs_grab_root(BTRFS_I(dir)->root);
+	root = BTRFS_I(inode)->root;
+
+	ret = btrfs_init_file_extent_tree(BTRFS_I(inode));
+	if (ret)
+		goto out;
+
+	ret = btrfs_get_free_objectid(root, &objectid);
+	if (ret)
+		goto out;
+	btrfs_set_inode_number(BTRFS_I(inode), objectid);
+
+	ret = xa_reserve(&root->inodes, objectid, GFP_NOFS);
+	if (ret)
+		goto out;
+	xa_reserved = true;
+
+	if (args->orphan) {
+		/*
+		 * O_TMPFILE, set link count to 0, so that after this point, we
+		 * fill in an inode item with the correct link count.
+		 */
+		set_nlink(inode, 0);
+	} else {
+		trace_btrfs_inode_request(dir);
+
+		ret = btrfs_set_inode_index(BTRFS_I(dir), &BTRFS_I(inode)->dir_index);
+		if (ret)
+			goto out;
+	}
+
+	if (S_ISDIR(inode->i_mode))
+		BTRFS_I(inode)->index_cnt = BTRFS_DIR_START_INDEX;
+
+	BTRFS_I(inode)->generation = trans->transid;
+	inode->i_generation = BTRFS_I(inode)->generation;
+
+	/*
+	 * We don't have any capability xattrs set here yet, shortcut any
+	 * queries for the xattrs here.  If we add them later via the inode
+	 * security init path or any other path this flag will be cleared.
+	 */
+	set_bit(BTRFS_INODE_NO_CAP_XATTR, &BTRFS_I(inode)->runtime_flags);
+
+	/*
+	 * Subvolumes don't inherit flags from their parent directory.
+	 * Originally this was probably by accident, but we probably can't
+	 * change it now without compatibility issues.
+	 */
+	if (!args->subvol)
+		btrfs_inherit_iflags(BTRFS_I(inode), BTRFS_I(dir));
+
+	btrfs_set_inode_mapping_order(BTRFS_I(inode));
+	if (S_ISREG(inode->i_mode)) {
+		if (btrfs_test_opt(fs_info, NODATASUM))
+			BTRFS_I(inode)->flags |= BTRFS_INODE_NODATASUM;
+		if (btrfs_test_opt(fs_info, NODATACOW))
+			BTRFS_I(inode)->flags |= BTRFS_INODE_NODATACOW |
+				BTRFS_INODE_NODATASUM;
+		btrfs_update_inode_mapping_flags(BTRFS_I(inode));
+	}
+
+	ret = btrfs_insert_inode_locked(inode);
+	if (ret < 0) {
+		if (!args->orphan)
+			BTRFS_I(dir)->index_cnt--;
+		goto out;
+	}
+
+	/*
+	 * We could have gotten an inode number from somebody who was fsynced
+	 * and then removed in this same transaction, so let's just set full
+	 * sync since it will be a full sync anyway and this will blow away the
+	 * old info in the log.
+	 */
+	btrfs_set_inode_full_sync(BTRFS_I(inode));
+
+	key[0].objectid = objectid;
+	key[0].type = BTRFS_INODE_ITEM_KEY;
+	key[0].offset = 0;
+
+	sizes[0] = sizeof(struct btrfs_inode_item);
+
+	if (!args->orphan) {
+		/*
+		 * Start new inodes with an inode_ref. This is slightly more
+		 * efficient for small numbers of hard links since they will
+		 * be packed into one item. Extended refs will kick in if we
+		 * add more hard links than can fit in the ref item.
+		 */
+		key[1].objectid = objectid;
+		key[1].type = BTRFS_INODE_REF_KEY;
+		if (args->subvol) {
+			key[1].offset = objectid;
+			sizes[1] = 2 + sizeof(*ref);
+		} else {
+			key[1].offset = btrfs_ino(BTRFS_I(dir));
+			sizes[1] = name->len + sizeof(*ref);
+		}
+	}
+
+	batch.keys = &key[0];
+	batch.data_sizes = &sizes[0];
+	batch.total_data_size = sizes[0] + (args->orphan ? 0 : sizes[1]);
+	batch.nr = args->orphan ? 1 : 2;
+	ret = btrfs_insert_empty_items(trans, root, path, &batch);
+	if (unlikely(ret != 0)) {
+		btrfs_abort_transaction(trans, ret);
+		goto discard;
+	}
+
+	ts = simple_inode_init_ts(inode);
+	BTRFS_I(inode)->i_otime_sec = ts.tv_sec;
+	BTRFS_I(inode)->i_otime_nsec = ts.tv_nsec;
+
+	/*
+	 * We're going to fill the inode item now, so at this point the inode
+	 * must be fully initialized.
+	 */
+
+	inode_item = btrfs_item_ptr(path->nodes[0], path->slots[0],
+				  struct btrfs_inode_item);
+	memzero_extent_buffer(path->nodes[0], (unsigned long)inode_item,
+			     sizeof(*inode_item));
+	fill_inode_item(trans, path->nodes[0], inode_item, inode);
+
+	if (!args->orphan) {
+		ref = btrfs_item_ptr(path->nodes[0], path->slots[0] + 1,
+				     struct btrfs_inode_ref);
+		ptr = (unsigned long)(ref + 1);
+		if (args->subvol) {
+			btrfs_set_inode_ref_name_len(path->nodes[0], ref, 2);
+			btrfs_set_inode_ref_index(path->nodes[0], ref, 0);
+			write_extent_buffer(path->nodes[0], "..", ptr, 2);
+		} else {
+			btrfs_set_inode_ref_name_len(path->nodes[0], ref,
+						     name->len);
+			btrfs_set_inode_ref_index(path->nodes[0], ref,
+						  BTRFS_I(inode)->dir_index);
+			write_extent_buffer(path->nodes[0], name->name, ptr,
+					    name->len);
+		}
+	}
+
+	/*
+	 * We don't need the path anymore, plus inheriting properties, adding
+	 * ACLs, security xattrs, orphan item or adding the link, will result in
+	 * allocating yet another path. So just free our path.
+	 */
+	btrfs_free_path(path);
+	path = NULL;
+
+	if (args->subvol) {
+		struct btrfs_inode *parent;
+
+		/*
+		 * Subvolumes inherit properties from their parent subvolume,
+		 * not the directory they were created in.
+		 */
+		parent = btrfs_iget(BTRFS_FIRST_FREE_OBJECTID, BTRFS_I(dir)->root);
+		if (IS_ERR(parent)) {
+			ret = PTR_ERR(parent);
+		} else {
+			ret = btrfs_inode_inherit_props(trans, BTRFS_I(inode),
+							parent);
+			iput(&parent->vfs_inode);
+		}
+	} else {
+		ret = btrfs_inode_inherit_props(trans, BTRFS_I(inode),
+						BTRFS_I(dir));
+	}
+	if (ret) {
+		btrfs_err(fs_info,
+			  "error inheriting props for ino %llu (root %llu): %pe",
+			  btrfs_ino(BTRFS_I(inode)), btrfs_root_id(root), ERR_PTR(ret));
+	}
+
+	/*
+	 * Subvolumes don't inherit ACLs or get passed to the LSM. This is
+	 * probably a bug.
+	 */
+	if (!args->subvol) {
+		ret = btrfs_init_inode_security(trans, args);
+		if (unlikely(ret)) {
+			btrfs_abort_transaction(trans, ret);
+			goto discard;
+		}
+	}
+
+	ret = btrfs_add_inode_to_root(BTRFS_I(inode), false);
+	if (WARN_ON(ret)) {
+		/* Shouldn't happen, we used xa_reserve() before. */
+		btrfs_abort_transaction(trans, ret);
+		goto discard;
+	}
+
+	trace_btrfs_inode_new(inode);
+	btrfs_set_inode_last_trans(trans, BTRFS_I(inode));
+
+	btrfs_update_root_times(trans, root);
+
+	if (args->orphan) {
+		ret = btrfs_orphan_add(trans, BTRFS_I(inode));
+		if (unlikely(ret)) {
+			btrfs_abort_transaction(trans, ret);
+			goto discard;
+		}
+	} else {
+		ret = btrfs_add_link(trans, BTRFS_I(dir), BTRFS_I(inode), name,
+				     false, BTRFS_I(inode)->dir_index);
+		if (unlikely(ret)) {
+			btrfs_abort_transaction(trans, ret);
+			goto discard;
+		}
+	}
+
+	return 0;
+
+discard:
+	/*
+	 * discard_new_inode() calls iput(), but the caller owns the reference
+	 * to the inode.
+	 */
+	ihold(inode);
+	discard_new_inode(inode);
+out:
+	if (xa_reserved)
+		xa_release(&root->inodes, objectid);
+
+	btrfs_free_path(path);
+	return ret;
+}
+
+/*
+ * utility function to add 'inode' into 'parent_inode' with
+ * a give name and a given sequence number.
+ * if 'add_backref' is true, also insert a backref from the
+ * inode to the parent directory.
+ */
+int btrfs_add_link(struct btrfs_trans_handle *trans,
+		   struct btrfs_inode *parent_inode, struct btrfs_inode *inode,
+		   const struct fscrypt_str *name, bool add_backref, u64 index)
+{
+	int ret = 0;
+	struct btrfs_key key;
+	struct btrfs_root *root = parent_inode->root;
+	u64 ino = btrfs_ino(inode);
+	u64 parent_ino = btrfs_ino(parent_inode);
+
+	if (unlikely(ino == BTRFS_FIRST_FREE_OBJECTID)) {
+		memcpy(&key, &inode->root->root_key, sizeof(key));
+	} else {
+		key.objectid = ino;
+		key.type = BTRFS_INODE_ITEM_KEY;
+		key.offset = 0;
+	}
+
+	if (unlikely(ino == BTRFS_FIRST_FREE_OBJECTID)) {
+		ret = btrfs_add_root_ref(trans, key.objectid,
+					 btrfs_root_id(root), parent_ino,
+					 index, name);
+	} else if (add_backref) {
+		ret = btrfs_insert_inode_ref(trans, root, name,
+					     ino, parent_ino, index);
+	}
+
+	/* Nothing to clean up yet */
+	if (ret)
+		return ret;
+
+	ret = btrfs_insert_dir_item(trans, name, parent_inode, &key,
+				    btrfs_inode_type(inode), index);
+	if (ret == -EEXIST || ret == -EOVERFLOW)
+		goto fail_dir_item;
+	else if (unlikely(ret)) {
+		btrfs_abort_transaction(trans, ret);
+		return ret;
+	}
+
+	btrfs_i_size_write(parent_inode, parent_inode->vfs_inode.i_size +
+			   name->len * 2);
+	inode_inc_iversion(&parent_inode->vfs_inode);
+	update_time_after_link_or_unlink(parent_inode);
+
+	ret = btrfs_update_inode(trans, parent_inode);
+	if (ret)
+		btrfs_abort_transaction(trans, ret);
+	return ret;
+
+fail_dir_item:
+	if (unlikely(ino == BTRFS_FIRST_FREE_OBJECTID)) {
+		u64 local_index;
+		int ret2;
+
+		ret2 = btrfs_del_root_ref(trans, key.objectid, btrfs_root_id(root),
+					  parent_ino, &local_index, name);
+		if (ret2)
+			btrfs_abort_transaction(trans, ret2);
+	} else if (add_backref) {
+		int ret2;
+
+		ret2 = btrfs_del_inode_ref(trans, root, name, ino, parent_ino, NULL);
+		if (ret2)
+			btrfs_abort_transaction(trans, ret2);
+	}
+
+	/* Return the original error code */
+	return ret;
+}
+
+static int btrfs_create_common(struct inode *dir, struct dentry *dentry,
+			       struct inode *inode)
+{
+	struct btrfs_fs_info *fs_info = inode_to_fs_info(dir);
+	struct btrfs_root *root = BTRFS_I(dir)->root;
+	struct btrfs_new_inode_args new_inode_args = {
+		.dir = dir,
+		.dentry = dentry,
+		.inode = inode,
+	};
+	unsigned int trans_num_items;
+	struct btrfs_trans_handle *trans;
+	int ret;
+
+	ret = btrfs_new_inode_prepare(&new_inode_args, &trans_num_items);
+	if (ret)
+		goto out_inode;
+
+	trans = btrfs_start_transaction(root, trans_num_items);
+	if (IS_ERR(trans)) {
+		ret = PTR_ERR(trans);
+		goto out_new_inode_args;
+	}
+
+	ret = btrfs_create_new_inode(trans, &new_inode_args);
+	if (!ret) {
+		if (S_ISDIR(inode->i_mode))
+			inode->i_opflags |= IOP_FASTPERM_MAY_EXEC;
+		d_instantiate_new(dentry, inode);
+	}
+
+	btrfs_end_transaction(trans);
+	btrfs_btree_balance_dirty(fs_info);
+out_new_inode_args:
+	btrfs_new_inode_args_destroy(&new_inode_args);
+out_inode:
+	if (ret)
+		iput(inode);
+	return ret;
+}
+
+static int btrfs_mknod(struct mnt_idmap *idmap, struct inode *dir,
+		       struct dentry *dentry, umode_t mode, dev_t rdev)
+{
+	struct inode *inode;
+
+	inode = new_inode(dir->i_sb);
+	if (!inode)
+		return -ENOMEM;
+	inode_init_owner(idmap, inode, dir, mode);
+	inode->i_op = &btrfs_special_inode_operations;
+	init_special_inode(inode, inode->i_mode, rdev);
+	return btrfs_create_common(dir, dentry, inode);
+}
+
+static int btrfs_create(struct mnt_idmap *idmap, struct inode *dir,
+			struct dentry *dentry, umode_t mode)
+{
+	struct inode *inode;
+
+	inode = new_inode(dir->i_sb);
+	if (!inode)
+		return -ENOMEM;
+	inode_init_owner(idmap, inode, dir, mode);
+	inode->i_fop = &btrfs_file_operations;
+	inode->i_op = &btrfs_file_inode_operations;
+	inode->i_mapping->a_ops = &btrfs_aops;
+	return btrfs_create_common(dir, dentry, inode);
+}
+
+static int btrfs_link(struct dentry *old_dentry, struct inode *dir,
+		      struct dentry *dentry)
+{
+	struct btrfs_trans_handle *trans = NULL;
+	struct btrfs_root *root = BTRFS_I(dir)->root;
+	struct inode *inode = d_inode(old_dentry);
+	struct btrfs_fs_info *fs_info = inode_to_fs_info(inode);
+	struct fscrypt_name fname;
+	u64 index;
+	int ret;
+
+	/* do not allow sys_link's with other subvols of the same device */
+	if (btrfs_root_id(root) != btrfs_root_id(BTRFS_I(inode)->root))
+		return -EXDEV;
+
+	if (inode->i_nlink >= BTRFS_LINK_MAX)
+		return -EMLINK;
+
+	ret = fscrypt_setup_filename(dir, &dentry->d_name, 0, &fname);
+	if (ret)
+		goto fail;
+
+	ret = btrfs_set_inode_index(BTRFS_I(dir), &index);
+	if (ret)
+		goto fail;
+
+	/*
+	 * 2 items for inode and inode ref
+	 * 2 items for dir items
+	 * 1 item for parent inode
+	 * 1 item for orphan item deletion if O_TMPFILE
+	 */
+	trans = btrfs_start_transaction(root, inode->i_nlink ? 5 : 6);
+	if (IS_ERR(trans)) {
+		ret = PTR_ERR(trans);
+		trans = NULL;
+		goto fail;
+	}
+
+	/* There are several dir indexes for this inode, clear the cache. */
+	BTRFS_I(inode)->dir_index = 0ULL;
+	inode_inc_iversion(inode);
+	inode_set_ctime_current(inode);
+
+	ret = btrfs_add_link(trans, BTRFS_I(dir), BTRFS_I(inode),
+			     &fname.disk_name, true, index);
+	if (ret)
+		goto fail;
+
+	/* Link added now we update the inode item with the new link count. */
+	inc_nlink(inode);
+	ret = btrfs_update_inode(trans, BTRFS_I(inode));
+	if (unlikely(ret)) {
+		btrfs_abort_transaction(trans, ret);
+		goto fail;
+	}
+
+	if (inode->i_nlink == 1) {
+		/*
+		 * If the new hard link count is 1, it's a file created with the
+		 * open(2) O_TMPFILE flag.
+		 */
+		ret = btrfs_orphan_del(trans, BTRFS_I(inode));
+		if (unlikely(ret)) {
+			btrfs_abort_transaction(trans, ret);
+			goto fail;
+		}
+	}
+
+	/* Grab reference for the new dentry passed to d_instantiate(). */
+	ihold(inode);
+	d_instantiate(dentry, inode);
+	btrfs_log_new_name(trans, old_dentry, NULL, 0, dentry->d_parent);
+
+fail:
+	fscrypt_free_filename(&fname);
+	if (trans)
+		btrfs_end_transaction(trans);
+	btrfs_btree_balance_dirty(fs_info);
+	return ret;
+}
+
+static struct dentry *btrfs_mkdir(struct mnt_idmap *idmap, struct inode *dir,
+				  struct dentry *dentry, umode_t mode)
+{
+	struct inode *inode;
+
+	inode = new_inode(dir->i_sb);
+	if (!inode)
+		return ERR_PTR(-ENOMEM);
+	inode_init_owner(idmap, inode, dir, mode);
+	inode->i_op = &btrfs_dir_inode_operations;
+	inode->i_fop = &btrfs_dir_file_operations;
+	return ERR_PTR(btrfs_create_common(dir, dentry, inode));
+}
+
+static noinline int uncompress_inline(struct btrfs_path *path,
+				      struct folio *folio,
+				      struct btrfs_file_extent_item *item)
+{
+	int ret;
+	struct extent_buffer *leaf = path->nodes[0];
+	const u32 blocksize = leaf->fs_info->sectorsize;
+	char *tmp;
+	size_t max_size;
+	unsigned long inline_size;
+	unsigned long ptr;
+	int compress_type;
+
+	compress_type = btrfs_file_extent_compression(leaf, item);
+	max_size = btrfs_file_extent_ram_bytes(leaf, item);
+	inline_size = btrfs_file_extent_inline_item_len(leaf, path->slots[0]);
+	tmp = kmalloc(inline_size, GFP_NOFS);
+	if (!tmp)
+		return -ENOMEM;
+	ptr = btrfs_file_extent_inline_start(item);
+
+	read_extent_buffer(leaf, tmp, ptr, inline_size);
+
+	max_size = min_t(unsigned long, blocksize, max_size);
+	ret = btrfs_decompress(compress_type, tmp, folio, 0, inline_size,
+			       max_size);
+
+	/*
+	 * decompression code contains a memset to fill in any space between the end
+	 * of the uncompressed data and the end of max_size in case the decompressed
+	 * data ends up shorter than ram_bytes.  That doesn't cover the hole between
+	 * the end of an inline extent and the beginning of the next block, so we
+	 * cover that region here.
+	 */
+
+	if (max_size < blocksize)
+		folio_zero_range(folio, max_size, blocksize - max_size);
+	kfree(tmp);
+	return ret;
+}
+
+static int read_inline_extent(struct btrfs_path *path, struct folio *folio)
+{
+	const u32 blocksize = path->nodes[0]->fs_info->sectorsize;
+	struct btrfs_file_extent_item *fi;
+	void *kaddr;
+	size_t copy_size;
+
+	if (!folio || folio_test_uptodate(folio))
+		return 0;
+
+	ASSERT(folio_pos(folio) == 0);
+
+	fi = btrfs_item_ptr(path->nodes[0], path->slots[0],
+			    struct btrfs_file_extent_item);
+	if (btrfs_file_extent_compression(path->nodes[0], fi) != BTRFS_COMPRESS_NONE)
+		return uncompress_inline(path, folio, fi);
+
+	copy_size = min_t(u64, blocksize,
+			  btrfs_file_extent_ram_bytes(path->nodes[0], fi));
+	kaddr = kmap_local_folio(folio, 0);
+	read_extent_buffer(path->nodes[0], kaddr,
+			   btrfs_file_extent_inline_start(fi), copy_size);
+	kunmap_local(kaddr);
+	if (copy_size < blocksize)
+		folio_zero_range(folio, copy_size, blocksize - copy_size);
+	return 0;
+}
+
+/*
+ * Lookup the first extent overlapping a range in a file.
+ *
+ * @inode:	file to search in
+ * @page:	page to read extent data into if the extent is inline
+ * @start:	file offset
+ * @len:	length of range starting at @start
+ *
+ * Return the first &struct extent_map which overlaps the given range, reading
+ * it from the B-tree and caching it if necessary. Note that there may be more
+ * extents which overlap the given range after the returned extent_map.
+ *
+ * If @page is not NULL and the extent is inline, this also reads the extent
+ * data directly into the page and marks the extent up to date in the io_tree.
+ *
+ * Return: ERR_PTR on error, non-NULL extent_map on success.
+ */
+struct extent_map *btrfs_get_extent(struct btrfs_inode *inode,
+				    struct folio *folio, u64 start, u64 len)
+{
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+	int ret = 0;
+	u64 extent_start = 0;
+	u64 extent_end = 0;
+	u64 objectid = btrfs_ino(inode);
+	int extent_type = -1;
+	struct btrfs_path *path = NULL;
+	struct btrfs_root *root = inode->root;
+	struct btrfs_file_extent_item *item;
+	struct extent_buffer *leaf;
+	struct btrfs_key found_key;
+	struct extent_map *em = NULL;
+	struct extent_map_tree *em_tree = &inode->extent_tree;
+
+	read_lock(&em_tree->lock);
+	em = btrfs_lookup_extent_mapping(em_tree, start, len);
+	read_unlock(&em_tree->lock);
+
+	if (em) {
+		if (em->start > start || btrfs_extent_map_end(em) <= start)
+			btrfs_free_extent_map(em);
+		else if (em->disk_bytenr == EXTENT_MAP_INLINE && folio)
+			btrfs_free_extent_map(em);
+		else
+			goto out;
+	}
+	em = btrfs_alloc_extent_map();
+	if (!em) {
+		ret = -ENOMEM;
+		goto out;
+	}
+	em->start = EXTENT_MAP_HOLE;
+	em->disk_bytenr = EXTENT_MAP_HOLE;
+	em->len = (u64)-1;
+
+	path = btrfs_alloc_path();
+	if (!path) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	/* Chances are we'll be called again, so go ahead and do readahead */
+	path->reada = READA_FORWARD;
+
+	/*
+	 * The same explanation in load_free_space_cache applies here as well,
+	 * we only read when we're loading the free space cache, and at that
+	 * point the commit_root has everything we need.
+	 */
+	if (btrfs_is_free_space_inode(inode)) {
+		path->search_commit_root = true;
+		path->skip_locking = true;
+	}
+
+	ret = btrfs_lookup_file_extent(NULL, root, path, objectid, start, 0);
+	if (ret < 0) {
+		goto out;
+	} else if (ret > 0) {
+		if (path->slots[0] == 0)
+			goto not_found;
+		path->slots[0]--;
+		ret = 0;
+	}
+
+	leaf = path->nodes[0];
+	item = btrfs_item_ptr(leaf, path->slots[0],
+			      struct btrfs_file_extent_item);
+	btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
+	if (found_key.objectid != objectid ||
+	    found_key.type != BTRFS_EXTENT_DATA_KEY) {
+		/*
+		 * If we backup past the first extent we want to move forward
+		 * and see if there is an extent in front of us, otherwise we'll
+		 * say there is a hole for our whole search range which can
+		 * cause problems.
+		 */
+		extent_end = start;
+		goto next;
+	}
+
+	extent_type = btrfs_file_extent_type(leaf, item);
+	extent_start = found_key.offset;
+	extent_end = btrfs_file_extent_end(path);
+	if (extent_type == BTRFS_FILE_EXTENT_REG ||
+	    extent_type == BTRFS_FILE_EXTENT_PREALLOC) {
+		/* Only regular file could have regular/prealloc extent */
+		if (unlikely(!S_ISREG(inode->vfs_inode.i_mode))) {
+			ret = -EUCLEAN;
+			btrfs_crit(fs_info,
+		"regular/prealloc extent found for non-regular inode %llu",
+				   btrfs_ino(inode));
+			goto out;
+		}
+		trace_btrfs_get_extent_show_fi_regular(inode, leaf, item,
+						       extent_start);
+	} else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
+		trace_btrfs_get_extent_show_fi_inline(inode, leaf, item,
+						      path->slots[0],
+						      extent_start);
+	}
+next:
+	if (start >= extent_end) {
+		path->slots[0]++;
+		if (path->slots[0] >= btrfs_header_nritems(leaf)) {
+			ret = btrfs_next_leaf(root, path);
+			if (ret < 0)
+				goto out;
+			else if (ret > 0)
+				goto not_found;
+
+			leaf = path->nodes[0];
+		}
+		btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
+		if (found_key.objectid != objectid ||
+		    found_key.type != BTRFS_EXTENT_DATA_KEY)
+			goto not_found;
+		if (start + len <= found_key.offset)
+			goto not_found;
+		if (start > found_key.offset)
+			goto next;
+
+		/* New extent overlaps with existing one */
+		em->start = start;
+		em->len = found_key.offset - start;
+		em->disk_bytenr = EXTENT_MAP_HOLE;
+		goto insert;
+	}
+
+	btrfs_extent_item_to_extent_map(inode, path, item, em);
+
+	if (extent_type == BTRFS_FILE_EXTENT_REG ||
+	    extent_type == BTRFS_FILE_EXTENT_PREALLOC) {
+		goto insert;
+	} else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
+		/*
+		 * Inline extent can only exist at file offset 0. This is
+		 * ensured by tree-checker and inline extent creation path.
+		 * Thus all members representing file offsets should be zero.
+		 */
+		ASSERT(extent_start == 0);
+		ASSERT(em->start == 0);
+
+		/*
+		 * btrfs_extent_item_to_extent_map() should have properly
+		 * initialized em members already.
+		 *
+		 * Other members are not utilized for inline extents.
+		 */
+		ASSERT(em->disk_bytenr == EXTENT_MAP_INLINE);
+		ASSERT(em->len == fs_info->sectorsize);
+
+		ret = read_inline_extent(path, folio);
+		if (ret < 0)
+			goto out;
+		goto insert;
+	}
+not_found:
+	em->start = start;
+	em->len = len;
+	em->disk_bytenr = EXTENT_MAP_HOLE;
+insert:
+	ret = 0;
+	btrfs_release_path(path);
+	if (unlikely(em->start > start || btrfs_extent_map_end(em) <= start)) {
+		btrfs_err(fs_info,
+			  "bad extent! em: [%llu %llu] passed [%llu %llu]",
+			  em->start, em->len, start, len);
+		ret = -EIO;
+		goto out;
+	}
+
+	write_lock(&em_tree->lock);
+	ret = btrfs_add_extent_mapping(inode, &em, start, len);
+	write_unlock(&em_tree->lock);
+out:
+	btrfs_free_path(path);
+
+	trace_btrfs_get_extent(root, inode, em);
+
+	if (ret) {
+		btrfs_free_extent_map(em);
+		return ERR_PTR(ret);
+	}
+	return em;
+}
+
+static bool btrfs_extent_readonly(struct btrfs_fs_info *fs_info, u64 bytenr)
+{
+	struct btrfs_block_group *block_group;
+	bool readonly = false;
+
+	block_group = btrfs_lookup_block_group(fs_info, bytenr);
+	if (!block_group || block_group->ro)
+		readonly = true;
+	if (block_group)
+		btrfs_put_block_group(block_group);
+	return readonly;
+}
+
+/*
+ * Check if we can do nocow write into the range [@offset, @offset + @len)
+ *
+ * @offset:	File offset
+ * @len:	The length to write, will be updated to the nocow writeable
+ *		range
+ * @orig_start:	(optional) Return the original file offset of the file extent
+ * @orig_len:	(optional) Return the original on-disk length of the file extent
+ * @ram_bytes:	(optional) Return the ram_bytes of the file extent
+ *
+ * Return:
+ * >0	and update @len if we can do nocow write
+ *  0	if we can't do nocow write
+ * <0	if error happened
+ *
+ * NOTE: This only checks the file extents, caller is responsible to wait for
+ *	 any ordered extents.
+ */
+noinline int can_nocow_extent(struct btrfs_inode *inode, u64 offset, u64 *len,
+			      struct btrfs_file_extent *file_extent,
+			      bool nowait)
+{
+	struct btrfs_root *root = inode->root;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct can_nocow_file_extent_args nocow_args = { 0 };
+	BTRFS_PATH_AUTO_FREE(path);
+	int ret;
+	struct extent_buffer *leaf;
+	struct extent_io_tree *io_tree = &inode->io_tree;
+	struct btrfs_file_extent_item *fi;
+	struct btrfs_key key;
+	int found_type;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+	path->nowait = nowait;
+
+	ret = btrfs_lookup_file_extent(NULL, root, path, btrfs_ino(inode),
+				       offset, 0);
+	if (ret < 0)
+		return ret;
+
+	if (ret == 1) {
+		if (path->slots[0] == 0) {
+			/* Can't find the item, must COW. */
+			return 0;
+		}
+		path->slots[0]--;
+	}
+	ret = 0;
+	leaf = path->nodes[0];
+	btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
+	if (key.objectid != btrfs_ino(inode) ||
+	    key.type != BTRFS_EXTENT_DATA_KEY) {
+		/* Not our file or wrong item type, must COW. */
+		return 0;
+	}
+
+	if (key.offset > offset) {
+		/* Wrong offset, must COW. */
+		return 0;
+	}
+
+	if (btrfs_file_extent_end(path) <= offset)
+		return 0;
+
+	fi = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_file_extent_item);
+	found_type = btrfs_file_extent_type(leaf, fi);
+
+	nocow_args.start = offset;
+	nocow_args.end = offset + *len - 1;
+	nocow_args.free_path = true;
+
+	ret = can_nocow_file_extent(path, &key, inode, &nocow_args);
+	/* can_nocow_file_extent() has freed the path. */
+	path = NULL;
+
+	if (ret != 1) {
+		/* Treat errors as not being able to NOCOW. */
+		return 0;
+	}
+
+	if (btrfs_extent_readonly(fs_info,
+				  nocow_args.file_extent.disk_bytenr +
+				  nocow_args.file_extent.offset))
+		return 0;
+
+	if (!(inode->flags & BTRFS_INODE_NODATACOW) &&
+	    found_type == BTRFS_FILE_EXTENT_PREALLOC) {
+		u64 range_end;
+
+		range_end = round_up(offset + nocow_args.file_extent.num_bytes,
+				     root->fs_info->sectorsize) - 1;
+		ret = btrfs_test_range_bit_exists(io_tree, offset, range_end,
+						  EXTENT_DELALLOC);
+		if (ret)
+			return -EAGAIN;
+	}
+
+	if (file_extent)
+		memcpy(file_extent, &nocow_args.file_extent, sizeof(*file_extent));
+
+	*len = nocow_args.file_extent.num_bytes;
+
+	return 1;
+}
+
+/* The callers of this must take lock_extent() */
+struct extent_map *btrfs_create_io_em(struct btrfs_inode *inode, u64 start,
+				      const struct btrfs_file_extent *file_extent,
+				      int type)
+{
+	struct extent_map *em;
+	int ret;
+
+	/*
+	 * Note the missing NOCOW type.
+	 *
+	 * For pure NOCOW writes, we should not create an io extent map, but
+	 * just reusing the existing one.
+	 * Only PREALLOC writes (NOCOW write into preallocated range) can
+	 * create an io extent map.
+	 */
+	ASSERT(type == BTRFS_ORDERED_PREALLOC ||
+	       type == BTRFS_ORDERED_COMPRESSED ||
+	       type == BTRFS_ORDERED_REGULAR);
+
+	switch (type) {
+	case BTRFS_ORDERED_PREALLOC:
+		/* We're only referring part of a larger preallocated extent. */
+		ASSERT(file_extent->num_bytes <= file_extent->ram_bytes);
+		break;
+	case BTRFS_ORDERED_REGULAR:
+		/* COW results a new extent matching our file extent size. */
+		ASSERT(file_extent->disk_num_bytes == file_extent->num_bytes);
+		ASSERT(file_extent->ram_bytes == file_extent->num_bytes);
+
+		/* Since it's a new extent, we should not have any offset. */
+		ASSERT(file_extent->offset == 0);
+		break;
+	case BTRFS_ORDERED_COMPRESSED:
+		/* Must be compressed. */
+		ASSERT(file_extent->compression != BTRFS_COMPRESS_NONE);
+
+		/*
+		 * Encoded write can make us to refer to part of the
+		 * uncompressed extent.
+		 */
+		ASSERT(file_extent->num_bytes <= file_extent->ram_bytes);
+		break;
+	}
+
+	em = btrfs_alloc_extent_map();
+	if (!em)
+		return ERR_PTR(-ENOMEM);
+
+	em->start = start;
+	em->len = file_extent->num_bytes;
+	em->disk_bytenr = file_extent->disk_bytenr;
+	em->disk_num_bytes = file_extent->disk_num_bytes;
+	em->ram_bytes = file_extent->ram_bytes;
+	em->generation = -1;
+	em->offset = file_extent->offset;
+	em->flags |= EXTENT_FLAG_PINNED;
+	if (type == BTRFS_ORDERED_COMPRESSED)
+		btrfs_extent_map_set_compression(em, file_extent->compression);
+
+	ret = btrfs_replace_extent_map_range(inode, em, true);
+	if (ret) {
+		btrfs_free_extent_map(em);
+		return ERR_PTR(ret);
+	}
+
+	/* em got 2 refs now, callers needs to do btrfs_free_extent_map once. */
+	return em;
+}
+
+/*
+ * For release_folio() and invalidate_folio() we have a race window where
+ * folio_end_writeback() is called but the subpage spinlock is not yet released.
+ * If we continue to release/invalidate the page, we could cause use-after-free
+ * for subpage spinlock.  So this function is to spin and wait for subpage
+ * spinlock.
+ */
+static void wait_subpage_spinlock(struct folio *folio)
+{
+	struct btrfs_fs_info *fs_info = folio_to_fs_info(folio);
+	struct btrfs_folio_state *bfs;
+
+	if (!btrfs_is_subpage(fs_info, folio))
+		return;
+
+	ASSERT(folio_test_private(folio) && folio_get_private(folio));
+	bfs = folio_get_private(folio);
+
+	/*
+	 * This may look insane as we just acquire the spinlock and release it,
+	 * without doing anything.  But we just want to make sure no one is
+	 * still holding the subpage spinlock.
+	 * And since the page is not dirty nor writeback, and we have page
+	 * locked, the only possible way to hold a spinlock is from the endio
+	 * function to clear page writeback.
+	 *
+	 * Here we just acquire the spinlock so that all existing callers
+	 * should exit and we're safe to release/invalidate the page.
+	 */
+	spin_lock_irq(&bfs->lock);
+	spin_unlock_irq(&bfs->lock);
+}
+
+static int btrfs_launder_folio(struct folio *folio)
+{
+	return btrfs_qgroup_free_data(folio_to_inode(folio), NULL, folio_pos(folio),
+				      folio_size(folio), NULL);
+}
+
+static bool __btrfs_release_folio(struct folio *folio, gfp_t gfp_flags)
+{
+	if (try_release_extent_mapping(folio, gfp_flags)) {
+		wait_subpage_spinlock(folio);
+		clear_folio_extent_mapped(folio);
+		return true;
+	}
+	return false;
+}
+
+static bool btrfs_release_folio(struct folio *folio, gfp_t gfp_flags)
+{
+	if (folio_test_writeback(folio) || folio_test_dirty(folio))
+		return false;
+	return __btrfs_release_folio(folio, gfp_flags);
+}
+
+#ifdef CONFIG_MIGRATION
+static int btrfs_migrate_folio(struct address_space *mapping,
+			     struct folio *dst, struct folio *src,
+			     enum migrate_mode mode)
+{
+	int ret = filemap_migrate_folio(mapping, dst, src, mode);
+
+	if (ret)
+		return ret;
+	return 0;
+}
+#else
+#define btrfs_migrate_folio NULL
+#endif
+
+static void btrfs_invalidate_folio(struct folio *folio, size_t offset,
+				 size_t length)
+{
+	struct btrfs_inode *inode = folio_to_inode(folio);
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+	struct extent_io_tree *tree = &inode->io_tree;
+	struct extent_state *cached_state = NULL;
+	u64 page_start = folio_pos(folio);
+	u64 page_end = page_start + folio_size(folio) - 1;
+	u64 cur;
+	int inode_evicting = inode_state_read_once(&inode->vfs_inode) & I_FREEING;
+
+	/*
+	 * We have folio locked so no new ordered extent can be created on this
+	 * page, nor bio can be submitted for this folio.
+	 *
+	 * But already submitted bio can still be finished on this folio.
+	 * Furthermore, endio function won't skip folio which has Ordered
+	 * already cleared, so it's possible for endio and
+	 * invalidate_folio to do the same ordered extent accounting twice
+	 * on one folio.
+	 *
+	 * So here we wait for any submitted bios to finish, so that we won't
+	 * do double ordered extent accounting on the same folio.
+	 */
+	folio_wait_writeback(folio);
+	wait_subpage_spinlock(folio);
+
+	/*
+	 * The invalidated blocks are going away; drop any fixup blocks among
+	 * them, data included, as they have no space reservation.
+	 */
+	btrfs_folio_clear_fixup_dirty(fs_info, folio, page_start + offset, length);
+
+	/*
+	 * For subpage case, we have call sites like
+	 * btrfs_punch_hole_lock_range() which passes range not aligned to
+	 * sectorsize.
+	 * If the range doesn't cover the full folio, we don't need to and
+	 * shouldn't clear page extent mapped, as folio->private can still
+	 * record subpage dirty bits for other part of the range.
+	 *
+	 * For cases that invalidate the full folio even the range doesn't
+	 * cover the full folio, like invalidating the last folio, we're
+	 * still safe to wait for ordered extent to finish.
+	 */
+	if (!(offset == 0 && length == folio_size(folio))) {
+		btrfs_release_folio(folio, GFP_NOFS);
+		return;
+	}
+
+	if (!inode_evicting)
+		btrfs_lock_extent(tree, page_start, page_end, &cached_state);
+
+	cur = page_start;
+	while (cur < page_end) {
+		struct btrfs_ordered_extent *ordered;
+		u64 range_end;
+		u32 range_len;
+		u32 extra_flags = 0;
+
+		ordered = btrfs_lookup_first_ordered_range(inode, cur,
+							   page_end + 1 - cur);
+		if (!ordered) {
+			range_end = page_end;
+			/*
+			 * No ordered extent covering this range, we are safe
+			 * to delete all extent states in the range.
+			 */
+			extra_flags = EXTENT_CLEAR_ALL_BITS;
+			goto next;
+		}
+		if (ordered->file_offset > cur) {
+			/*
+			 * There is a range between [cur, oe->file_offset) not
+			 * covered by any ordered extent.
+			 * We are safe to delete all extent states, and handle
+			 * the ordered extent in the next iteration.
+			 */
+			range_end = ordered->file_offset - 1;
+			extra_flags = EXTENT_CLEAR_ALL_BITS;
+			goto next;
+		}
+
+		range_end = min(ordered->file_offset + ordered->num_bytes - 1,
+				page_end);
+		ASSERT(range_end + 1 - cur < U32_MAX);
+		range_len = range_end + 1 - cur;
+		/*
+		 * If the range is not dirty, the range has been submitted and
+		 * since we have waited for the writeback, endio has been
+		 * executed, thus we must skip the range to avoid double
+		 * accounting for the ordered extent.
+		 */
+		if (!btrfs_folio_test_dirty(fs_info, folio, cur, range_len))
+			goto next;
+
+		/*
+		 * The range is dirty meaning it has not been submitted.
+		 * Here we need to truncate the OE range as the range will never
+		 * be submitted.
+		 *
+		 * IO on this page will never be started, so we need to account
+		 * for any ordered extents now. Don't clear EXTENT_DELALLOC_NEW
+		 * here, must leave that up for the ordered extent completion.
+		 *
+		 * This will also unlock the range for incoming
+		 * btrfs_finish_ordered_io().
+		 */
+		if (!inode_evicting)
+			btrfs_clear_extent_bit(tree, cur, range_end,
+					       EXTENT_DELALLOC |
+					       EXTENT_LOCKED | EXTENT_DO_ACCOUNTING |
+					       EXTENT_DEFRAG, &cached_state);
+
+		btrfs_mark_ordered_extent_truncated(ordered, cur - ordered->file_offset);
+
+		/*
+		 * If the ordered extent has finished, we're safe to delete all
+		 * the extent states of the range, otherwise
+		 * btrfs_finish_ordered_io() will get executed by endio for
+		 * other pages, so we can't delete extent states.
+		 */
+		if (btrfs_dec_test_ordered_pending(inode, &ordered,
+						   cur, range_end + 1 - cur)) {
+			btrfs_finish_ordered_io(ordered);
+			/*
+			 * The ordered extent has finished, now we're again
+			 * safe to delete all extent states of the range.
+			 */
+			extra_flags = EXTENT_CLEAR_ALL_BITS;
+		}
+next:
+		if (ordered)
+			btrfs_put_ordered_extent(ordered);
+		/*
+		 * Qgroup reserved space handler
+		 * Sector(s) here will be either:
+		 *
+		 * 1) Already written to disk or bio already finished
+		 *    Then its QGROUP_RESERVED bit in io_tree is already cleared.
+		 *    Qgroup will be handled by its qgroup_record then.
+		 *    btrfs_qgroup_free_data() call will do nothing here.
+		 *
+		 * 2) Not written to disk yet
+		 *    Then btrfs_qgroup_free_data() call will clear the
+		 *    QGROUP_RESERVED bit of its io_tree, and free the qgroup
+		 *    reserved data space.
+		 *    Since the IO will never happen for this page.
+		 */
+		btrfs_qgroup_free_data(inode, NULL, cur, range_end + 1 - cur, NULL);
+		if (!inode_evicting)
+			btrfs_clear_extent_bit(tree, cur, range_end, EXTENT_LOCKED |
+					       EXTENT_DELALLOC | EXTENT_DO_ACCOUNTING |
+					       EXTENT_DEFRAG | extra_flags,
+					       &cached_state);
+		cur = range_end + 1;
+	}
+	btrfs_folio_clear_dirty(fs_info, folio, page_start, folio_size(folio));
+	btrfs_clear_folio_dirty_tag(folio);
+	if (!inode_evicting)
+		__btrfs_release_folio(folio, GFP_NOFS);
+	clear_folio_extent_mapped(folio);
+}
+
+static int btrfs_truncate(struct btrfs_inode *inode, bool skip_writeback)
+{
+	struct btrfs_truncate_control control = {
+		.inode = inode,
+		.ino = btrfs_ino(inode),
+		.min_type = BTRFS_EXTENT_DATA_KEY,
+		.clear_extent_range = true,
+		.new_size = inode->vfs_inode.i_size,
+	};
+	struct btrfs_root *root = inode->root;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_block_rsv rsv;
+	int ret;
+	struct btrfs_trans_handle *trans;
+	const u64 min_size = btrfs_calc_metadata_size(fs_info, 1);
+	const u64 lock_start = round_down(inode->vfs_inode.i_size, fs_info->sectorsize);
+	const u64 i_size_up = round_up(inode->vfs_inode.i_size, fs_info->sectorsize);
+
+	/* Our inode is locked and the i_size can't be changed concurrently. */
+	btrfs_assert_inode_locked(inode);
+
+	if (!skip_writeback) {
+		ret = btrfs_wait_ordered_range(inode, lock_start, (u64)-1);
+		if (ret)
+			return ret;
+	}
+
+	/*
+	 * Yes ladies and gentlemen, this is indeed ugly.  We have a couple of
+	 * things going on here:
+	 *
+	 * 1) We need to reserve space to update our inode.
+	 *
+	 * 2) We need to have something to cache all the space that is going to
+	 * be free'd up by the truncate operation, but also have some slack
+	 * space reserved in case it uses space during the truncate (thank you
+	 * very much snapshotting).
+	 *
+	 * And we need these to be separate.  The fact is we can use a lot of
+	 * space doing the truncate, and we have no earthly idea how much space
+	 * we will use, so we need the truncate reservation to be separate so it
+	 * doesn't end up using space reserved for updating the inode.  We also
+	 * need to be able to stop the transaction and start a new one, which
+	 * means we need to be able to update the inode several times, and we
+	 * have no idea of knowing how many times that will be, so we can't just
+	 * reserve 1 item for the entirety of the operation, so that has to be
+	 * done separately as well.
+	 *
+	 * So that leaves us with
+	 *
+	 * 1) rsv - for the truncate reservation, which we will steal from the
+	 * transaction reservation.
+	 * 2) fs_info->trans_block_rsv - this will have 1 items worth left for
+	 * updating the inode.
+	 */
+	btrfs_init_metadata_block_rsv(fs_info, &rsv, BTRFS_BLOCK_RSV_TEMP);
+	rsv.size = min_size;
+	rsv.failfast = true;
+
+	/*
+	 * 1 for the truncate slack space
+	 * 1 for updating the inode.
+	 */
+	trans = btrfs_start_transaction(root, 2);
+	if (IS_ERR(trans)) {
+		ret = PTR_ERR(trans);
+		goto out;
+	}
+
+	/* Migrate the slack space for the truncate to our reserve */
+	ret = btrfs_block_rsv_migrate(&fs_info->trans_block_rsv, &rsv,
+				      min_size, false);
+	/*
+	 * We have reserved 2 metadata units when we started the transaction and
+	 * min_size matches 1 unit, so this should never fail, but if it does,
+	 * it's not critical we just fail truncation.
+	 */
+	if (WARN_ON(ret)) {
+		btrfs_end_transaction(trans);
+		goto out;
+	}
+
+	trans->block_rsv = &rsv;
+
+	while (1) {
+		struct extent_state *cached_state = NULL;
+
+		btrfs_lock_extent(&inode->io_tree, lock_start, (u64)-1, &cached_state);
+		/*
+		 * We want to drop from the next block forward in case this new
+		 * size is not block aligned since we will be keeping the last
+		 * block of the extent just the way it is.
+		 */
+		btrfs_drop_extent_map_range(inode, i_size_up, (u64)-1, false);
+
+		ret = btrfs_truncate_inode_items(trans, root, &control);
+
+		inode_sub_bytes(&inode->vfs_inode, control.sub_bytes);
+		btrfs_inode_safe_disk_i_size_write(inode, control.last_size);
+
+		btrfs_unlock_extent(&inode->io_tree, lock_start, (u64)-1, &cached_state);
+
+		trans->block_rsv = &fs_info->trans_block_rsv;
+		if (ret != -ENOSPC && ret != -EAGAIN)
+			break;
+
+		ret = btrfs_update_inode(trans, inode);
+		if (ret)
+			break;
+
+		btrfs_end_transaction(trans);
+		btrfs_btree_balance_dirty(fs_info);
+
+		trans = btrfs_start_transaction(root, 2);
+		if (IS_ERR(trans)) {
+			ret = PTR_ERR(trans);
+			trans = NULL;
+			break;
+		}
+
+		btrfs_block_rsv_release(fs_info, &rsv, -1, NULL);
+		ret = btrfs_block_rsv_migrate(&fs_info->trans_block_rsv,
+					      &rsv, min_size, false);
+		/*
+		 * We have reserved 2 metadata units when we started the
+		 * transaction and min_size matches 1 unit, so this should never
+		 * fail, but if it does, it's not critical we just fail truncation.
+		 */
+		if (WARN_ON(ret))
+			break;
+
+		trans->block_rsv = &rsv;
+	}
+
+	/*
+	 * We can't call btrfs_truncate_block inside a trans handle as we could
+	 * deadlock with freeze, if we got BTRFS_NEED_TRUNCATE_BLOCK then we
+	 * know we've truncated everything except the last little bit, and can
+	 * do btrfs_truncate_block and then update the disk_i_size.
+	 */
+	if (ret == BTRFS_NEED_TRUNCATE_BLOCK) {
+		btrfs_end_transaction(trans);
+		btrfs_btree_balance_dirty(fs_info);
+
+		ret = btrfs_truncate_block(inode, inode->vfs_inode.i_size,
+					   inode->vfs_inode.i_size, (u64)-1);
+		if (ret)
+			goto out;
+		trans = btrfs_start_transaction(root, 1);
+		if (IS_ERR(trans)) {
+			ret = PTR_ERR(trans);
+			goto out;
+		}
+		btrfs_inode_safe_disk_i_size_write(inode, 0);
+	}
+
+	if (trans) {
+		int ret2;
+
+		trans->block_rsv = &fs_info->trans_block_rsv;
+		ret2 = btrfs_update_inode(trans, inode);
+		if (ret2 && !ret)
+			ret = ret2;
+
+		ret2 = btrfs_end_transaction(trans);
+		if (ret2 && !ret)
+			ret = ret2;
+		btrfs_btree_balance_dirty(fs_info);
+	}
+out:
+	btrfs_block_rsv_release(fs_info, &rsv, (u64)-1, NULL);
+	/*
+	 * So if we truncate and then write and fsync we normally would just
+	 * write the extents that changed, which is a problem if we need to
+	 * first truncate that entire inode.  So set this flag so we write out
+	 * all of the extents in the inode to the sync log so we're completely
+	 * safe.
+	 *
+	 * If no extents were dropped or trimmed we don't need to force the next
+	 * fsync to truncate all the inode's items from the log and re-log them
+	 * all. This means the truncate operation did not change the file size,
+	 * or changed it to a smaller size but there was only an implicit hole
+	 * between the old i_size and the new i_size, and there were no prealloc
+	 * extents beyond i_size to drop.
+	 */
+	if (control.extents_found > 0)
+		btrfs_set_inode_full_sync(inode);
+
+	return ret;
+}
+
+struct inode *btrfs_new_subvol_inode(struct mnt_idmap *idmap,
+				     struct inode *dir)
+{
+	struct inode *inode;
+
+	inode = new_inode(dir->i_sb);
+	if (inode) {
+		/*
+		 * Subvolumes don't inherit the sgid bit or the parent's gid if
+		 * the parent's sgid bit is set. This is probably a bug.
+		 */
+		inode_init_owner(idmap, inode, NULL,
+				 S_IFDIR | (~current_umask() & S_IRWXUGO));
+		inode->i_op = &btrfs_dir_inode_operations;
+		inode->i_fop = &btrfs_dir_file_operations;
+	}
+	return inode;
+}
+
+struct inode *btrfs_alloc_inode(struct super_block *sb)
+{
+	struct btrfs_fs_info *fs_info = btrfs_sb(sb);
+	struct btrfs_inode *ei;
+	struct inode *inode;
+
+	ei = alloc_inode_sb(sb, btrfs_inode_cachep, GFP_KERNEL);
+	if (!ei)
+		return NULL;
+
+	ei->root = NULL;
+	ei->generation = 0;
+	ei->last_trans = 0;
+	ei->last_sub_trans = 0;
+	ei->logged_trans = 0;
+	ei->delalloc_bytes = 0;
+	/* new_delalloc_bytes and last_dir_index_offset are in a union. */
+	ei->new_delalloc_bytes = 0;
+	ei->defrag_bytes = 0;
+	ei->disk_i_size = 0;
+	ei->flags = 0;
+	ei->ro_flags = 0;
+	/*
+	 * ->index_cnt will be properly initialized later when creating a new
+	 * inode (btrfs_create_new_inode()) or when reading an existing inode
+	 * from disk (btrfs_read_locked_inode()).
+	 */
+	ei->csum_bytes = 0;
+	ei->dir_index = 0;
+	ei->last_unlink_trans = 0;
+	ei->last_reflink_trans = 0;
+	ei->last_log_commit = 0;
+
+	spin_lock_init(&ei->lock);
+	ei->outstanding_extents = 0;
+	if (sb->s_magic != BTRFS_TEST_MAGIC)
+		btrfs_init_metadata_block_rsv(fs_info, &ei->block_rsv,
+					      BTRFS_BLOCK_RSV_DELALLOC);
+	ei->runtime_flags = 0;
+	ei->prop_compress = BTRFS_COMPRESS_NONE;
+	ei->defrag_compress = BTRFS_COMPRESS_NONE;
+
+	ei->delayed_node = NULL;
+
+	ei->i_otime_sec = 0;
+	ei->i_otime_nsec = 0;
+
+	inode = &ei->vfs_inode;
+	btrfs_extent_map_tree_init(&ei->extent_tree);
+
+	/* This io tree sets the valid inode. */
+	btrfs_extent_io_tree_init(fs_info, &ei->io_tree, IO_TREE_INODE_IO);
+	ei->io_tree.inode = ei;
+
+	ei->file_extent_tree = NULL;
+
+	mutex_init(&ei->log_mutex);
+	spin_lock_init(&ei->ordered_tree_lock);
+	ei->ordered_tree = RB_ROOT;
+	ei->ordered_tree_last = NULL;
+	INIT_LIST_HEAD(&ei->delalloc_inodes);
+	INIT_LIST_HEAD(&ei->delayed_iput);
+	init_rwsem(&ei->i_mmap_lock);
+
+	return inode;
+}
+
+#ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
+void btrfs_test_destroy_inode(struct inode *inode)
+{
+	btrfs_drop_extent_map_range(BTRFS_I(inode), 0, (u64)-1, false);
+	kfree(BTRFS_I(inode)->file_extent_tree);
+	kmem_cache_free(btrfs_inode_cachep, BTRFS_I(inode));
+}
+#endif
+
+void btrfs_free_inode(struct inode *inode)
+{
+	kfree(BTRFS_I(inode)->file_extent_tree);
+	kmem_cache_free(btrfs_inode_cachep, BTRFS_I(inode));
+}
+
+void btrfs_destroy_inode(struct inode *vfs_inode)
+{
+	struct btrfs_ordered_extent *ordered;
+	struct btrfs_inode *inode = BTRFS_I(vfs_inode);
+	struct btrfs_root *root = inode->root;
+	bool freespace_inode;
+
+	WARN_ON(!hlist_empty(&vfs_inode->i_dentry));
+	WARN_ON(vfs_inode->i_data.nrpages);
+	WARN_ON(inode->block_rsv.reserved);
+	WARN_ON(inode->block_rsv.size);
+	WARN_ON(inode->outstanding_extents);
+	if (!S_ISDIR(vfs_inode->i_mode)) {
+		WARN_ON(inode->delalloc_bytes);
+		WARN_ON(inode->new_delalloc_bytes);
+		WARN_ON(inode->csum_bytes);
+	}
+	if (!root || !btrfs_is_data_reloc_root(root))
+		WARN_ON(inode->defrag_bytes);
+
+	/*
+	 * This can happen where we create an inode, but somebody else also
+	 * created the same inode and we need to destroy the one we already
+	 * created.
+	 */
+	if (!root)
+		return;
+
+	/*
+	 * If this is a free space inode do not take the ordered extents lockdep
+	 * map.
+	 */
+	freespace_inode = btrfs_is_free_space_inode(inode);
+
+	while (1) {
+		ordered = btrfs_lookup_first_ordered_extent(inode, (u64)-1);
+		if (!ordered)
+			break;
+		else {
+			btrfs_err(root->fs_info,
+				  "found ordered extent %llu %llu on inode cleanup",
+				  ordered->file_offset, ordered->num_bytes);
+
+			if (!freespace_inode)
+				btrfs_lockdep_acquire(root->fs_info, btrfs_ordered_extent);
+
+			btrfs_remove_ordered_extent(ordered);
+			btrfs_put_ordered_extent(ordered);
+			btrfs_put_ordered_extent(ordered);
+		}
+	}
+	btrfs_qgroup_check_reserved_leak(inode);
+	btrfs_del_inode_from_root(inode);
+	btrfs_drop_extent_map_range(inode, 0, (u64)-1, false);
+	btrfs_inode_clear_file_extent_range(inode, 0, (u64)-1);
+	btrfs_put_root(inode->root);
+}
+
+int btrfs_drop_inode(struct inode *inode)
+{
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+
+	if (root == NULL)
+		return 1;
+
+	/* the snap/subvol tree is on deleting */
+	if (btrfs_root_refs(&root->root_item) == 0)
+		return 1;
+	else
+		return inode_generic_drop(inode);
+}
+
+static void init_once(void *foo)
+{
+	struct btrfs_inode *ei = foo;
+
+	inode_init_once(&ei->vfs_inode);
+}
+
+void __cold btrfs_destroy_cachep(void)
+{
+	/*
+	 * Make sure all delayed rcu free inodes are flushed before we
+	 * destroy cache.
+	 */
+	rcu_barrier();
+	kmem_cache_destroy(btrfs_inode_cachep);
+}
+
+int __init btrfs_init_cachep(void)
+{
+	btrfs_inode_cachep = kmem_cache_create("btrfs_inode",
+			sizeof(struct btrfs_inode), 0,
+			SLAB_RECLAIM_ACCOUNT | SLAB_ACCOUNT,
+			init_once);
+	if (!btrfs_inode_cachep)
+		return -ENOMEM;
+
+	return 0;
+}
+
+static int btrfs_getattr(struct mnt_idmap *idmap,
+			 const struct path *path, struct kstat *stat,
+			 u32 request_mask, unsigned int flags)
+{
+	u64 delalloc_bytes;
+	u64 inode_bytes;
+	struct inode *inode = d_inode(path->dentry);
+	u32 blocksize = btrfs_sb(inode->i_sb)->sectorsize;
+	u32 bi_flags = BTRFS_I(inode)->flags;
+	u32 bi_ro_flags = BTRFS_I(inode)->ro_flags;
+
+	stat->result_mask |= STATX_BTIME;
+	stat->btime.tv_sec = BTRFS_I(inode)->i_otime_sec;
+	stat->btime.tv_nsec = BTRFS_I(inode)->i_otime_nsec;
+	if (bi_flags & BTRFS_INODE_APPEND)
+		stat->attributes |= STATX_ATTR_APPEND;
+	if (bi_flags & BTRFS_INODE_COMPRESS)
+		stat->attributes |= STATX_ATTR_COMPRESSED;
+	if (bi_flags & BTRFS_INODE_IMMUTABLE)
+		stat->attributes |= STATX_ATTR_IMMUTABLE;
+	if (bi_flags & BTRFS_INODE_NODUMP)
+		stat->attributes |= STATX_ATTR_NODUMP;
+	if (bi_ro_flags & BTRFS_INODE_RO_VERITY)
+		stat->attributes |= STATX_ATTR_VERITY;
+
+	stat->attributes_mask |= (STATX_ATTR_APPEND |
+				  STATX_ATTR_COMPRESSED |
+				  STATX_ATTR_IMMUTABLE |
+				  STATX_ATTR_NODUMP);
+
+	generic_fillattr(idmap, request_mask, inode, stat);
+	stat->dev = BTRFS_I(inode)->root->anon_dev;
+
+	stat->subvol = btrfs_root_id(BTRFS_I(inode)->root);
+	stat->result_mask |= STATX_SUBVOL;
+
+	spin_lock(&BTRFS_I(inode)->lock);
+	delalloc_bytes = S_ISREG(inode->i_mode) ?
+			 BTRFS_I(inode)->new_delalloc_bytes : 0;
+	inode_bytes = inode_get_bytes(inode);
+	spin_unlock(&BTRFS_I(inode)->lock);
+	stat->blocks = (ALIGN(inode_bytes, blocksize) +
+			ALIGN(delalloc_bytes, blocksize)) >> SECTOR_SHIFT;
+	return 0;
+}
+
+static int btrfs_rename_exchange(struct inode *old_dir,
+			      struct dentry *old_dentry,
+			      struct inode *new_dir,
+			      struct dentry *new_dentry)
+{
+	struct btrfs_fs_info *fs_info = inode_to_fs_info(old_dir);
+	struct btrfs_trans_handle *trans;
+	unsigned int trans_num_items;
+	struct btrfs_root *root = BTRFS_I(old_dir)->root;
+	struct btrfs_root *dest = BTRFS_I(new_dir)->root;
+	struct inode *new_inode = new_dentry->d_inode;
+	struct inode *old_inode = old_dentry->d_inode;
+	struct btrfs_rename_ctx old_rename_ctx;
+	struct btrfs_rename_ctx new_rename_ctx;
+	u64 old_ino = btrfs_ino(BTRFS_I(old_inode));
+	u64 new_ino = btrfs_ino(BTRFS_I(new_inode));
+	u64 old_idx = 0;
+	u64 new_idx = 0;
+	int ret;
+	int ret2;
+	bool need_abort = false;
+	bool logs_pinned = false;
+	struct fscrypt_name old_fname, new_fname;
+	struct fscrypt_str *old_name, *new_name;
+
+	/*
+	 * For non-subvolumes allow exchange only within one subvolume, in the
+	 * same inode namespace. Two subvolumes (represented as directory) can
+	 * be exchanged as they're a logical link and have a fixed inode number.
+	 */
+	if (root != dest &&
+	    (old_ino != BTRFS_FIRST_FREE_OBJECTID ||
+	     new_ino != BTRFS_FIRST_FREE_OBJECTID))
+		return -EXDEV;
+
+	ret = fscrypt_setup_filename(old_dir, &old_dentry->d_name, 0, &old_fname);
+	if (ret)
+		return ret;
+
+	ret = fscrypt_setup_filename(new_dir, &new_dentry->d_name, 0, &new_fname);
+	if (ret) {
+		fscrypt_free_filename(&old_fname);
+		return ret;
+	}
+
+	old_name = &old_fname.disk_name;
+	new_name = &new_fname.disk_name;
+
+	/* close the race window with snapshot create/destroy ioctl */
+	if (old_ino == BTRFS_FIRST_FREE_OBJECTID ||
+	    new_ino == BTRFS_FIRST_FREE_OBJECTID)
+		down_read(&fs_info->subvol_sem);
+
+	/*
+	 * For each inode:
+	 * 1 to remove old dir item
+	 * 1 to remove old dir index
+	 * 1 to add new dir item
+	 * 1 to add new dir index
+	 * 1 to update parent inode
+	 *
+	 * If the parents are the same, we only need to account for one
+	 */
+	trans_num_items = (old_dir == new_dir ? 9 : 10);
+	if (old_ino == BTRFS_FIRST_FREE_OBJECTID) {
+		/*
+		 * 1 to remove old root ref
+		 * 1 to remove old root backref
+		 * 1 to add new root ref
+		 * 1 to add new root backref
+		 */
+		trans_num_items += 4;
+	} else {
+		/*
+		 * 1 to update inode item
+		 * 1 to remove old inode ref
+		 * 1 to add new inode ref
+		 */
+		trans_num_items += 3;
+	}
+	if (new_ino == BTRFS_FIRST_FREE_OBJECTID)
+		trans_num_items += 4;
+	else
+		trans_num_items += 3;
+	trans = btrfs_start_transaction(root, trans_num_items);
+	if (IS_ERR(trans)) {
+		ret = PTR_ERR(trans);
+		goto out_notrans;
+	}
+
+	if (dest != root) {
+		ret = btrfs_record_root_in_trans(trans, dest);
+		if (ret)
+			goto out_fail;
+	}
+
+	/*
+	 * We need to find a free sequence number both in the source and
+	 * in the destination directory for the exchange.
+	 */
+	ret = btrfs_set_inode_index(BTRFS_I(new_dir), &old_idx);
+	if (ret)
+		goto out_fail;
+	ret = btrfs_set_inode_index(BTRFS_I(old_dir), &new_idx);
+	if (ret)
+		goto out_fail;
+
+	BTRFS_I(old_inode)->dir_index = 0ULL;
+	BTRFS_I(new_inode)->dir_index = 0ULL;
+
+	/* Reference for the source. */
+	if (old_ino == BTRFS_FIRST_FREE_OBJECTID) {
+		/* force full log commit if subvolume involved. */
+		btrfs_set_log_full_commit(trans);
+	} else {
+		ret = btrfs_insert_inode_ref(trans, dest, new_name, old_ino,
+					     btrfs_ino(BTRFS_I(new_dir)),
+					     old_idx);
+		if (ret)
+			goto out_fail;
+		need_abort = true;
+	}
+
+	/* And now for the dest. */
+	if (new_ino == BTRFS_FIRST_FREE_OBJECTID) {
+		/* force full log commit if subvolume involved. */
+		btrfs_set_log_full_commit(trans);
+	} else {
+		ret = btrfs_insert_inode_ref(trans, root, old_name, new_ino,
+					     btrfs_ino(BTRFS_I(old_dir)),
+					     new_idx);
+		if (ret) {
+			if (unlikely(need_abort))
+				btrfs_abort_transaction(trans, ret);
+			goto out_fail;
+		}
+	}
+
+	/* Update inode version and ctime/mtime. */
+	inode_inc_iversion(old_dir);
+	inode_inc_iversion(new_dir);
+	inode_inc_iversion(old_inode);
+	inode_inc_iversion(new_inode);
+	simple_rename_timestamp(old_dir, old_dentry, new_dir, new_dentry);
+
+	if (old_ino != BTRFS_FIRST_FREE_OBJECTID &&
+	    new_ino != BTRFS_FIRST_FREE_OBJECTID) {
+		/*
+		 * If we are renaming in the same directory (and it's not for
+		 * root entries) pin the log early to prevent any concurrent
+		 * task from logging the directory after we removed the old
+		 * entries and before we add the new entries, otherwise that
+		 * task can sync a log without any entry for the inodes we are
+		 * renaming and therefore replaying that log, if a power failure
+		 * happens after syncing the log, would result in deleting the
+		 * inodes.
+		 *
+		 * If the rename affects two different directories, we want to
+		 * make sure the that there's no log commit that contains
+		 * updates for only one of the directories but not for the
+		 * other.
+		 *
+		 * If we are renaming an entry for a root, we don't care about
+		 * log updates since we called btrfs_set_log_full_commit().
+		 */
+		btrfs_pin_log_trans(root);
+		btrfs_pin_log_trans(dest);
+		logs_pinned = true;
+	}
+
+	if (old_dentry->d_parent != new_dentry->d_parent) {
+		btrfs_record_unlink_dir(trans, BTRFS_I(old_dir),
+					BTRFS_I(old_inode), true);
+		btrfs_record_unlink_dir(trans, BTRFS_I(new_dir),
+					BTRFS_I(new_inode), true);
+	}
+
+	/* src is a subvolume */
+	if (old_ino == BTRFS_FIRST_FREE_OBJECTID) {
+		ret = btrfs_unlink_subvol(trans, BTRFS_I(old_dir), old_dentry);
+		if (unlikely(ret)) {
+			btrfs_abort_transaction(trans, ret);
+			goto out_fail;
+		}
+	} else { /* src is an inode */
+		ret = __btrfs_unlink_inode(trans, BTRFS_I(old_dir),
+					   BTRFS_I(old_dentry->d_inode),
+					   old_name, &old_rename_ctx);
+		if (unlikely(ret)) {
+			btrfs_abort_transaction(trans, ret);
+			goto out_fail;
+		}
+		ret = btrfs_update_inode(trans, BTRFS_I(old_inode));
+		if (unlikely(ret)) {
+			btrfs_abort_transaction(trans, ret);
+			goto out_fail;
+		}
+	}
+
+	/* dest is a subvolume */
+	if (new_ino == BTRFS_FIRST_FREE_OBJECTID) {
+		ret = btrfs_unlink_subvol(trans, BTRFS_I(new_dir), new_dentry);
+		if (unlikely(ret)) {
+			btrfs_abort_transaction(trans, ret);
+			goto out_fail;
+		}
+	} else { /* dest is an inode */
+		ret = __btrfs_unlink_inode(trans, BTRFS_I(new_dir),
+					   BTRFS_I(new_dentry->d_inode),
+					   new_name, &new_rename_ctx);
+		if (unlikely(ret)) {
+			btrfs_abort_transaction(trans, ret);
+			goto out_fail;
+		}
+		ret = btrfs_update_inode(trans, BTRFS_I(new_inode));
+		if (unlikely(ret)) {
+			btrfs_abort_transaction(trans, ret);
+			goto out_fail;
+		}
+	}
+
+	ret = btrfs_add_link(trans, BTRFS_I(new_dir), BTRFS_I(old_inode),
+			     new_name, false, old_idx);
+	if (unlikely(ret)) {
+		btrfs_abort_transaction(trans, ret);
+		goto out_fail;
+	}
+
+	ret = btrfs_add_link(trans, BTRFS_I(old_dir), BTRFS_I(new_inode),
+			     old_name, false, new_idx);
+	if (unlikely(ret)) {
+		btrfs_abort_transaction(trans, ret);
+		goto out_fail;
+	}
+
+	if (old_inode->i_nlink == 1)
+		BTRFS_I(old_inode)->dir_index = old_idx;
+	if (new_inode->i_nlink == 1)
+		BTRFS_I(new_inode)->dir_index = new_idx;
+
+	/*
+	 * Do the log updates for all inodes.
+	 *
+	 * If either entry is for a root we don't need to update the logs since
+	 * we've called btrfs_set_log_full_commit() before.
+	 */
+	if (logs_pinned) {
+		btrfs_log_new_name(trans, old_dentry, BTRFS_I(old_dir),
+				   old_rename_ctx.index, new_dentry->d_parent);
+		btrfs_log_new_name(trans, new_dentry, BTRFS_I(new_dir),
+				   new_rename_ctx.index, old_dentry->d_parent);
+	}
+
+out_fail:
+	if (logs_pinned) {
+		btrfs_end_log_trans(root);
+		btrfs_end_log_trans(dest);
+	}
+	ret2 = btrfs_end_transaction(trans);
+	ret = ret ? ret : ret2;
+out_notrans:
+	if (new_ino == BTRFS_FIRST_FREE_OBJECTID ||
+	    old_ino == BTRFS_FIRST_FREE_OBJECTID)
+		up_read(&fs_info->subvol_sem);
+
+	fscrypt_free_filename(&new_fname);
+	fscrypt_free_filename(&old_fname);
+	return ret;
+}
+
+static struct inode *new_whiteout_inode(struct mnt_idmap *idmap,
+					struct inode *dir)
+{
+	struct inode *inode;
+
+	inode = new_inode(dir->i_sb);
+	if (inode) {
+		inode_init_owner(idmap, inode, dir,
+				 S_IFCHR | WHITEOUT_MODE);
+		inode->i_op = &btrfs_special_inode_operations;
+		init_special_inode(inode, inode->i_mode, WHITEOUT_DEV);
+	}
+	return inode;
+}
+
+static int btrfs_rename(struct mnt_idmap *idmap,
+			struct inode *old_dir, struct dentry *old_dentry,
+			struct inode *new_dir, struct dentry *new_dentry,
+			unsigned int flags)
+{
+	struct btrfs_fs_info *fs_info = inode_to_fs_info(old_dir);
+	struct btrfs_new_inode_args whiteout_args = {
+		.dir = old_dir,
+		.dentry = old_dentry,
+	};
+	struct btrfs_trans_handle *trans;
+	unsigned int trans_num_items;
+	struct btrfs_root *root = BTRFS_I(old_dir)->root;
+	struct btrfs_root *dest = BTRFS_I(new_dir)->root;
+	struct inode *new_inode = d_inode(new_dentry);
+	struct inode *old_inode = d_inode(old_dentry);
+	struct btrfs_rename_ctx rename_ctx;
+	u64 index = 0;
+	int ret;
+	int ret2;
+	u64 old_ino = btrfs_ino(BTRFS_I(old_inode));
+	struct fscrypt_name old_fname, new_fname;
+	bool logs_pinned = false;
+
+	if (btrfs_ino(BTRFS_I(new_dir)) == BTRFS_EMPTY_SUBVOL_DIR_OBJECTID)
+		return -EPERM;
+
+	/* we only allow rename subvolume link between subvolumes */
+	if (old_ino != BTRFS_FIRST_FREE_OBJECTID && root != dest)
+		return -EXDEV;
+
+	if (old_ino == BTRFS_EMPTY_SUBVOL_DIR_OBJECTID ||
+	    (new_inode && btrfs_ino(BTRFS_I(new_inode)) == BTRFS_FIRST_FREE_OBJECTID))
+		return -ENOTEMPTY;
+
+	if (S_ISDIR(old_inode->i_mode) && new_inode &&
+	    new_inode->i_size > BTRFS_EMPTY_DIR_SIZE)
+		return -ENOTEMPTY;
+
+	ret = fscrypt_setup_filename(old_dir, &old_dentry->d_name, 0, &old_fname);
+	if (ret)
+		return ret;
+
+	ret = fscrypt_setup_filename(new_dir, &new_dentry->d_name, 0, &new_fname);
+	if (ret) {
+		fscrypt_free_filename(&old_fname);
+		return ret;
+	}
+
+	/* check for collisions, even if the  name isn't there */
+	ret = btrfs_check_dir_item_collision(dest, new_dir->i_ino, &new_fname.disk_name);
+	if (ret) {
+		if (ret == -EEXIST) {
+			/* we shouldn't get
+			 * eexist without a new_inode */
+			if (WARN_ON(!new_inode)) {
+				goto out_fscrypt_names;
+			}
+		} else {
+			/* maybe -EOVERFLOW */
+			goto out_fscrypt_names;
+		}
+	}
+	ret = 0;
+
+	/*
+	 * we're using rename to replace one file with another.  Start IO on it
+	 * now so  we don't add too much work to the end of the transaction
+	 */
+	if (new_inode && S_ISREG(old_inode->i_mode) && new_inode->i_size)
+		filemap_flush(old_inode->i_mapping);
+
+	if (flags & RENAME_WHITEOUT) {
+		whiteout_args.inode = new_whiteout_inode(idmap, old_dir);
+		if (!whiteout_args.inode) {
+			ret = -ENOMEM;
+			goto out_fscrypt_names;
+		}
+		ret = btrfs_new_inode_prepare(&whiteout_args, &trans_num_items);
+		if (ret)
+			goto out_whiteout_inode;
+	} else {
+		/* 1 to update the old parent inode. */
+		trans_num_items = 1;
+	}
+
+	if (old_ino == BTRFS_FIRST_FREE_OBJECTID) {
+		/* Close the race window with snapshot create/destroy ioctl */
+		down_read(&fs_info->subvol_sem);
+		/*
+		 * 1 to remove old root ref
+		 * 1 to remove old root backref
+		 * 1 to add new root ref
+		 * 1 to add new root backref
+		 */
+		trans_num_items += 4;
+	} else {
+		/*
+		 * 1 to update inode
+		 * 1 to remove old inode ref
+		 * 1 to add new inode ref
+		 */
+		trans_num_items += 3;
+	}
+	/*
+	 * 1 to remove old dir item
+	 * 1 to remove old dir index
+	 * 1 to add new dir item
+	 * 1 to add new dir index
+	 */
+	trans_num_items += 4;
+	/* 1 to update new parent inode if it's not the same as the old parent */
+	if (new_dir != old_dir)
+		trans_num_items++;
+	if (new_inode) {
+		/*
+		 * 1 to update inode
+		 * 1 to remove inode ref
+		 * 1 to remove dir item
+		 * 1 to remove dir index
+		 * 1 to possibly add orphan item
+		 */
+		trans_num_items += 5;
+	}
+	trans = btrfs_start_transaction(root, trans_num_items);
+	if (IS_ERR(trans)) {
+		ret = PTR_ERR(trans);
+		goto out_notrans;
+	}
+
+	if (dest != root) {
+		ret = btrfs_record_root_in_trans(trans, dest);
+		if (ret)
+			goto out_fail;
+	}
+
+	ret = btrfs_set_inode_index(BTRFS_I(new_dir), &index);
+	if (ret)
+		goto out_fail;
+
+	BTRFS_I(old_inode)->dir_index = 0ULL;
+	if (unlikely(old_ino == BTRFS_FIRST_FREE_OBJECTID)) {
+		/* force full log commit if subvolume involved. */
+		btrfs_set_log_full_commit(trans);
+	} else {
+		ret = btrfs_insert_inode_ref(trans, dest, &new_fname.disk_name,
+					     old_ino, btrfs_ino(BTRFS_I(new_dir)),
+					     index);
+		if (ret)
+			goto out_fail;
+	}
+
+	inode_inc_iversion(old_dir);
+	inode_inc_iversion(new_dir);
+	inode_inc_iversion(old_inode);
+	simple_rename_timestamp(old_dir, old_dentry, new_dir, new_dentry);
+
+	if (old_ino != BTRFS_FIRST_FREE_OBJECTID) {
+		/*
+		 * If we are renaming in the same directory (and it's not a
+		 * root entry) pin the log to prevent any concurrent task from
+		 * logging the directory after we removed the old entry and
+		 * before we add the new entry, otherwise that task can sync
+		 * a log without any entry for the inode we are renaming and
+		 * therefore replaying that log, if a power failure happens
+		 * after syncing the log, would result in deleting the inode.
+		 *
+		 * If the rename affects two different directories, we want to
+		 * make sure the that there's no log commit that contains
+		 * updates for only one of the directories but not for the
+		 * other.
+		 *
+		 * If we are renaming an entry for a root, we don't care about
+		 * log updates since we called btrfs_set_log_full_commit().
+		 */
+		btrfs_pin_log_trans(root);
+		btrfs_pin_log_trans(dest);
+		logs_pinned = true;
+	}
+
+	if (old_dentry->d_parent != new_dentry->d_parent)
+		btrfs_record_unlink_dir(trans, BTRFS_I(old_dir),
+					BTRFS_I(old_inode), true);
+
+	if (unlikely(old_ino == BTRFS_FIRST_FREE_OBJECTID)) {
+		ret = btrfs_unlink_subvol(trans, BTRFS_I(old_dir), old_dentry);
+		if (unlikely(ret)) {
+			btrfs_abort_transaction(trans, ret);
+			goto out_fail;
+		}
+	} else {
+		ret = __btrfs_unlink_inode(trans, BTRFS_I(old_dir),
+					   BTRFS_I(d_inode(old_dentry)),
+					   &old_fname.disk_name, &rename_ctx);
+		if (unlikely(ret)) {
+			btrfs_abort_transaction(trans, ret);
+			goto out_fail;
+		}
+		ret = btrfs_update_inode(trans, BTRFS_I(old_inode));
+		if (unlikely(ret)) {
+			btrfs_abort_transaction(trans, ret);
+			goto out_fail;
+		}
+	}
+
+	if (new_inode) {
+		inode_inc_iversion(new_inode);
+		if (unlikely(btrfs_ino(BTRFS_I(new_inode)) ==
+			     BTRFS_EMPTY_SUBVOL_DIR_OBJECTID)) {
+			ret = btrfs_unlink_subvol(trans, BTRFS_I(new_dir), new_dentry);
+			if (unlikely(ret)) {
+				btrfs_abort_transaction(trans, ret);
+				goto out_fail;
+			}
+			BUG_ON(new_inode->i_nlink == 0);
+		} else {
+			ret = btrfs_unlink_inode(trans, BTRFS_I(new_dir),
+						 BTRFS_I(d_inode(new_dentry)),
+						 &new_fname.disk_name);
+			if (unlikely(ret)) {
+				btrfs_abort_transaction(trans, ret);
+				goto out_fail;
+			}
+		}
+		if (new_inode->i_nlink == 0) {
+			ret = btrfs_orphan_add(trans,
+					BTRFS_I(d_inode(new_dentry)));
+			if (unlikely(ret)) {
+				btrfs_abort_transaction(trans, ret);
+				goto out_fail;
+			}
+		}
+	}
+
+	ret = btrfs_add_link(trans, BTRFS_I(new_dir), BTRFS_I(old_inode),
+			     &new_fname.disk_name, false, index);
+	if (unlikely(ret)) {
+		btrfs_abort_transaction(trans, ret);
+		goto out_fail;
+	}
+
+	if (old_inode->i_nlink == 1)
+		BTRFS_I(old_inode)->dir_index = index;
+
+	if (logs_pinned)
+		btrfs_log_new_name(trans, old_dentry, BTRFS_I(old_dir),
+				   rename_ctx.index, new_dentry->d_parent);
+
+	if (flags & RENAME_WHITEOUT) {
+		ret = btrfs_create_new_inode(trans, &whiteout_args);
+		if (unlikely(ret)) {
+			btrfs_abort_transaction(trans, ret);
+			goto out_fail;
+		} else {
+			unlock_new_inode(whiteout_args.inode);
+			iput(whiteout_args.inode);
+			whiteout_args.inode = NULL;
+		}
+	}
+out_fail:
+	if (logs_pinned) {
+		btrfs_end_log_trans(root);
+		btrfs_end_log_trans(dest);
+	}
+	ret2 = btrfs_end_transaction(trans);
+	ret = ret ? ret : ret2;
+out_notrans:
+	if (old_ino == BTRFS_FIRST_FREE_OBJECTID)
+		up_read(&fs_info->subvol_sem);
+	if (flags & RENAME_WHITEOUT)
+		btrfs_new_inode_args_destroy(&whiteout_args);
+out_whiteout_inode:
+	if (flags & RENAME_WHITEOUT)
+		iput(whiteout_args.inode);
+out_fscrypt_names:
+	fscrypt_free_filename(&old_fname);
+	fscrypt_free_filename(&new_fname);
+	return ret;
+}
+
+static int btrfs_rename2(struct mnt_idmap *idmap, struct inode *old_dir,
+			 struct dentry *old_dentry, struct inode *new_dir,
+			 struct dentry *new_dentry, unsigned int flags)
+{
+	int ret;
+
+	if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT))
+		return -EINVAL;
+
+	if (flags & RENAME_EXCHANGE)
+		ret = btrfs_rename_exchange(old_dir, old_dentry, new_dir,
+					    new_dentry);
+	else
+		ret = btrfs_rename(idmap, old_dir, old_dentry, new_dir,
+				   new_dentry, flags);
+
+	btrfs_btree_balance_dirty(BTRFS_I(new_dir)->root->fs_info);
+
+	return ret;
+}
+
+struct btrfs_delalloc_work {
+	struct inode *inode;
+	struct completion completion;
+	struct list_head list;
+	struct btrfs_work work;
+};
+
+static void btrfs_run_delalloc_work(struct btrfs_work *work)
+{
+	struct btrfs_delalloc_work *delalloc_work;
+	struct inode *inode;
+
+	delalloc_work = container_of(work, struct btrfs_delalloc_work,
+				     work);
+	inode = delalloc_work->inode;
+	filemap_flush(inode->i_mapping);
+	if (test_bit(BTRFS_INODE_HAS_ASYNC_EXTENT,
+				&BTRFS_I(inode)->runtime_flags))
+		filemap_flush(inode->i_mapping);
+
+	iput(inode);
+	complete(&delalloc_work->completion);
+}
+
+static struct btrfs_delalloc_work *btrfs_alloc_delalloc_work(struct inode *inode)
+{
+	struct btrfs_delalloc_work *work;
+
+	work = kmalloc_obj(*work, GFP_NOFS);
+	if (!work)
+		return NULL;
+
+	init_completion(&work->completion);
+	INIT_LIST_HEAD(&work->list);
+	work->inode = inode;
+	btrfs_init_work(&work->work, btrfs_run_delalloc_work, NULL);
+
+	return work;
+}
+
+/*
+ * some fairly slow code that needs optimization. This walks the list
+ * of all the inodes with pending delalloc and forces them to disk.
+ */
+static int start_delalloc_inodes(struct btrfs_root *root, long *nr_to_write,
+				 bool snapshot, bool in_reclaim_context)
+{
+	struct btrfs_delalloc_work *work, *next;
+	LIST_HEAD(works);
+	LIST_HEAD(splice);
+	int ret = 0;
+
+	mutex_lock(&root->delalloc_mutex);
+	spin_lock(&root->delalloc_lock);
+	list_splice_init(&root->delalloc_inodes, &splice);
+	while (!list_empty(&splice)) {
+		struct btrfs_inode *inode;
+		struct inode *tmp_inode;
+
+		inode = list_first_entry(&splice, struct btrfs_inode, delalloc_inodes);
+
+		list_move_tail(&inode->delalloc_inodes, &root->delalloc_inodes);
+
+		if (in_reclaim_context &&
+		    test_bit(BTRFS_INODE_NO_DELALLOC_FLUSH, &inode->runtime_flags))
+			continue;
+
+		tmp_inode = igrab(&inode->vfs_inode);
+		if (!tmp_inode) {
+			cond_resched_lock(&root->delalloc_lock);
+			continue;
+		}
+		spin_unlock(&root->delalloc_lock);
+
+		if (snapshot)
+			set_bit(BTRFS_INODE_SNAPSHOT_FLUSH, &inode->runtime_flags);
+		if (nr_to_write == NULL) {
+			work = btrfs_alloc_delalloc_work(tmp_inode);
+			if (!work) {
+				iput(tmp_inode);
+				ret = -ENOMEM;
+				goto out;
+			}
+			list_add_tail(&work->list, &works);
+			btrfs_queue_work(root->fs_info->flush_workers,
+					 &work->work);
+		} else {
+			ret = filemap_flush_nr(tmp_inode->i_mapping,
+					nr_to_write);
+			btrfs_add_delayed_iput(inode);
+
+			if (ret || *nr_to_write <= 0)
+				goto out;
+		}
+		cond_resched();
+		spin_lock(&root->delalloc_lock);
+	}
+	spin_unlock(&root->delalloc_lock);
+
+out:
+	list_for_each_entry_safe(work, next, &works, list) {
+		list_del_init(&work->list);
+		wait_for_completion(&work->completion);
+		kfree(work);
+	}
+
+	if (!list_empty(&splice)) {
+		spin_lock(&root->delalloc_lock);
+		list_splice_tail(&splice, &root->delalloc_inodes);
+		spin_unlock(&root->delalloc_lock);
+	}
+	mutex_unlock(&root->delalloc_mutex);
+	return ret;
+}
+
+int btrfs_start_delalloc_snapshot(struct btrfs_root *root, bool in_reclaim_context)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+
+	if (unlikely(BTRFS_FS_ERROR(fs_info)))
+		return -EROFS;
+	return start_delalloc_inodes(root, NULL, true, in_reclaim_context);
+}
+
+int btrfs_start_delalloc_roots(struct btrfs_fs_info *fs_info, long nr,
+			       bool in_reclaim_context)
+{
+	long *nr_to_write = nr == LONG_MAX ? NULL : &nr;
+	struct btrfs_root *root;
+	LIST_HEAD(splice);
+	int ret;
+
+	if (unlikely(BTRFS_FS_ERROR(fs_info)))
+		return -EROFS;
+
+	mutex_lock(&fs_info->delalloc_root_mutex);
+	spin_lock(&fs_info->delalloc_root_lock);
+	list_splice_init(&fs_info->delalloc_roots, &splice);
+	while (!list_empty(&splice)) {
+		root = list_first_entry(&splice, struct btrfs_root,
+					delalloc_root);
+		root = btrfs_grab_root(root);
+		BUG_ON(!root);
+		list_move_tail(&root->delalloc_root,
+			       &fs_info->delalloc_roots);
+		spin_unlock(&fs_info->delalloc_root_lock);
+
+		ret = start_delalloc_inodes(root, nr_to_write, false,
+				in_reclaim_context);
+		btrfs_put_root(root);
+		if (ret < 0 || nr <= 0)
+			goto out;
+		spin_lock(&fs_info->delalloc_root_lock);
+	}
+	spin_unlock(&fs_info->delalloc_root_lock);
+
+	ret = 0;
+out:
+	if (!list_empty(&splice)) {
+		spin_lock(&fs_info->delalloc_root_lock);
+		list_splice_tail(&splice, &fs_info->delalloc_roots);
+		spin_unlock(&fs_info->delalloc_root_lock);
+	}
+	mutex_unlock(&fs_info->delalloc_root_mutex);
+	return ret;
+}
+
+static int btrfs_symlink(struct mnt_idmap *idmap, struct inode *dir,
+			 struct dentry *dentry, const char *symname)
+{
+	struct btrfs_fs_info *fs_info = inode_to_fs_info(dir);
+	struct btrfs_trans_handle *trans;
+	struct btrfs_root *root = BTRFS_I(dir)->root;
+	struct btrfs_path *path;
+	struct btrfs_key key;
+	struct inode *inode;
+	struct btrfs_new_inode_args new_inode_args = {
+		.dir = dir,
+		.dentry = dentry,
+	};
+	unsigned int trans_num_items;
+	int ret;
+	int name_len;
+	int datasize;
+	unsigned long ptr;
+	struct btrfs_file_extent_item *ei;
+	struct extent_buffer *leaf;
+
+	name_len = strlen(symname);
+	/*
+	 * Symlinks utilize uncompressed inline extent data, which should not
+	 * reach block size.
+	 */
+	if (name_len > BTRFS_MAX_INLINE_DATA_SIZE(fs_info) ||
+	    name_len >= fs_info->sectorsize)
+		return -ENAMETOOLONG;
+
+	inode = new_inode(dir->i_sb);
+	if (!inode)
+		return -ENOMEM;
+	inode_init_owner(idmap, inode, dir, S_IFLNK | S_IRWXUGO);
+	inode->i_op = &btrfs_symlink_inode_operations;
+	inode_nohighmem(inode);
+	inode->i_mapping->a_ops = &btrfs_aops;
+	btrfs_i_size_write(BTRFS_I(inode), name_len);
+	inode_set_bytes(inode, name_len);
+
+	new_inode_args.inode = inode;
+	ret = btrfs_new_inode_prepare(&new_inode_args, &trans_num_items);
+	if (ret)
+		goto out_inode;
+	/* 1 additional item for the inline extent */
+	trans_num_items++;
+
+	trans = btrfs_start_transaction(root, trans_num_items);
+	if (IS_ERR(trans)) {
+		ret = PTR_ERR(trans);
+		goto out_new_inode_args;
+	}
+
+	ret = btrfs_create_new_inode(trans, &new_inode_args);
+	if (ret)
+		goto out;
+
+	path = btrfs_alloc_path();
+	if (unlikely(!path)) {
+		ret = -ENOMEM;
+		btrfs_abort_transaction(trans, ret);
+		discard_new_inode(inode);
+		inode = NULL;
+		goto out;
+	}
+	key.objectid = btrfs_ino(BTRFS_I(inode));
+	key.type = BTRFS_EXTENT_DATA_KEY;
+	key.offset = 0;
+	datasize = btrfs_file_extent_calc_inline_size(name_len);
+	ret = btrfs_insert_empty_item(trans, root, path, &key, datasize);
+	if (unlikely(ret)) {
+		btrfs_abort_transaction(trans, ret);
+		btrfs_free_path(path);
+		discard_new_inode(inode);
+		inode = NULL;
+		goto out;
+	}
+	leaf = path->nodes[0];
+	ei = btrfs_item_ptr(leaf, path->slots[0],
+			    struct btrfs_file_extent_item);
+	btrfs_set_file_extent_generation(leaf, ei, trans->transid);
+	btrfs_set_file_extent_type(leaf, ei,
+				   BTRFS_FILE_EXTENT_INLINE);
+	btrfs_set_file_extent_encryption(leaf, ei, 0);
+	btrfs_set_file_extent_compression(leaf, ei, 0);
+	btrfs_set_file_extent_other_encoding(leaf, ei, 0);
+	btrfs_set_file_extent_ram_bytes(leaf, ei, name_len);
+
+	ptr = btrfs_file_extent_inline_start(ei);
+	write_extent_buffer(leaf, symname, ptr, name_len);
+	btrfs_free_path(path);
+
+	d_instantiate_new(dentry, inode);
+	ret = 0;
+out:
+	btrfs_end_transaction(trans);
+	btrfs_btree_balance_dirty(fs_info);
+out_new_inode_args:
+	btrfs_new_inode_args_destroy(&new_inode_args);
+out_inode:
+	if (ret)
+		iput(inode);
+	return ret;
+}
+
+static struct btrfs_trans_handle *insert_prealloc_file_extent(
+				       struct btrfs_trans_handle *trans_in,
+				       struct btrfs_inode *inode,
+				       struct btrfs_key *ins,
+				       u64 file_offset)
+{
+	struct btrfs_file_extent_item stack_fi;
+	struct btrfs_replace_extent_info extent_info;
+	struct btrfs_trans_handle *trans = trans_in;
+	struct btrfs_path *path;
+	u64 start = ins->objectid;
+	u64 len = ins->offset;
+	u64 qgroup_released = 0;
+	int ret;
+
+	memset(&stack_fi, 0, sizeof(stack_fi));
+
+	btrfs_set_stack_file_extent_type(&stack_fi, BTRFS_FILE_EXTENT_PREALLOC);
+	btrfs_set_stack_file_extent_disk_bytenr(&stack_fi, start);
+	btrfs_set_stack_file_extent_disk_num_bytes(&stack_fi, len);
+	btrfs_set_stack_file_extent_num_bytes(&stack_fi, len);
+	btrfs_set_stack_file_extent_ram_bytes(&stack_fi, len);
+	btrfs_set_stack_file_extent_compression(&stack_fi, BTRFS_COMPRESS_NONE);
+	/* Encryption and other encoding is reserved and all 0 */
+
+	ret = btrfs_qgroup_release_data(inode, file_offset, len, &qgroup_released);
+	if (ret < 0)
+		return ERR_PTR(ret);
+
+	if (trans) {
+		ret = insert_reserved_file_extent(trans, inode,
+						  file_offset, &stack_fi,
+						  true, qgroup_released);
+		if (ret)
+			goto free_qgroup;
+		return trans;
+	}
+
+	extent_info.disk_offset = start;
+	extent_info.disk_len = len;
+	extent_info.data_offset = 0;
+	extent_info.data_len = len;
+	extent_info.file_offset = file_offset;
+	extent_info.extent_buf = (char *)&stack_fi;
+	extent_info.is_new_extent = true;
+	extent_info.update_times = true;
+	extent_info.qgroup_reserved = qgroup_released;
+	extent_info.insertions = 0;
+
+	path = btrfs_alloc_path();
+	if (!path) {
+		ret = -ENOMEM;
+		goto free_qgroup;
+	}
+
+	ret = btrfs_replace_file_extents(inode, path, file_offset,
+				     file_offset + len - 1, &extent_info,
+				     &trans);
+	btrfs_free_path(path);
+	if (ret)
+		goto free_qgroup;
+	return trans;
+
+free_qgroup:
+	/*
+	 * We have released qgroup data range at the beginning of the function,
+	 * and normally qgroup_released bytes will be freed when committing
+	 * transaction.
+	 * But if we error out early, we have to free what we have released
+	 * or we leak qgroup data reservation.
+	 */
+	btrfs_qgroup_free_refroot(inode->root->fs_info,
+			btrfs_root_id(inode->root), qgroup_released,
+			BTRFS_QGROUP_RSV_DATA);
+	return ERR_PTR(ret);
+}
+
+static int __btrfs_prealloc_file_range(struct inode *inode, int mode,
+				       u64 start, u64 num_bytes, u64 min_size,
+				       loff_t actual_len, u64 *alloc_hint,
+				       struct btrfs_trans_handle *trans)
+{
+	struct btrfs_fs_info *fs_info = inode_to_fs_info(inode);
+	struct extent_map *em;
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	struct btrfs_key ins;
+	u64 cur_offset = start;
+	u64 clear_offset = start;
+	u64 i_size;
+	u64 cur_bytes;
+	u64 last_alloc = (u64)-1;
+	int ret = 0;
+	bool own_trans = true;
+	u64 end = start + num_bytes - 1;
+
+	if (trans)
+		own_trans = false;
+	while (num_bytes > 0) {
+		cur_bytes = min_t(u64, num_bytes, SZ_256M);
+		cur_bytes = max(cur_bytes, min_size);
+		/*
+		 * If we are severely fragmented we could end up with really
+		 * small allocations, so if the allocator is returning small
+		 * chunks lets make its job easier by only searching for those
+		 * sized chunks.
+		 */
+		cur_bytes = min(cur_bytes, last_alloc);
+		ret = btrfs_reserve_extent(root, cur_bytes, cur_bytes,
+				min_size, 0, *alloc_hint, &ins, true, false);
+		if (ret)
+			break;
+
+		/*
+		 * We've reserved this space, and thus converted it from
+		 * ->bytes_may_use to ->bytes_reserved.  Any error that happens
+		 * from here on out we will only need to clear our reservation
+		 * for the remaining unreserved area, so advance our
+		 * clear_offset by our extent size.
+		 */
+		clear_offset += ins.offset;
+
+		last_alloc = ins.offset;
+		trans = insert_prealloc_file_extent(trans, BTRFS_I(inode),
+						    &ins, cur_offset);
+		/*
+		 * Now that we inserted the prealloc extent we can finally
+		 * decrement the number of reservations in the block group.
+		 * If we did it before, we could race with relocation and have
+		 * relocation miss the reserved extent, making it fail later.
+		 */
+		btrfs_dec_block_group_reservations(fs_info, ins.objectid);
+		if (IS_ERR(trans)) {
+			ret = PTR_ERR(trans);
+			btrfs_free_reserved_extent(fs_info, ins.objectid,
+						   ins.offset, false);
+			break;
+		}
+
+		em = btrfs_alloc_extent_map();
+		if (!em) {
+			btrfs_drop_extent_map_range(BTRFS_I(inode), cur_offset,
+					    cur_offset + ins.offset - 1, false);
+			btrfs_set_inode_full_sync(BTRFS_I(inode));
+			goto next;
+		}
+
+		em->start = cur_offset;
+		em->len = ins.offset;
+		em->disk_bytenr = ins.objectid;
+		em->offset = 0;
+		em->disk_num_bytes = ins.offset;
+		em->ram_bytes = ins.offset;
+		em->flags |= EXTENT_FLAG_PREALLOC;
+		em->generation = trans->transid;
+
+		ret = btrfs_replace_extent_map_range(BTRFS_I(inode), em, true);
+		btrfs_free_extent_map(em);
+next:
+		num_bytes -= ins.offset;
+		cur_offset += ins.offset;
+		*alloc_hint = ins.objectid + ins.offset;
+
+		inode_inc_iversion(inode);
+		inode_set_ctime_current(inode);
+		BTRFS_I(inode)->flags |= BTRFS_INODE_PREALLOC;
+		if (!(mode & FALLOC_FL_KEEP_SIZE) &&
+		    (actual_len > inode->i_size) &&
+		    (cur_offset > inode->i_size)) {
+			u64 range_start;
+			u64 range_end;
+
+			if (cur_offset > actual_len)
+				i_size = actual_len;
+			else
+				i_size = cur_offset;
+
+			/*
+			 * Make sure the file_extent_tree covers the entire
+			 * range [old_i_size, new_i_size) before we update
+			 * disk_i_size. Without this, a previous KEEP_SIZE
+			 * prealloc that extended past i_size (and was lost
+			 * across umount/mount because file_extent_tree is
+			 * only populated up to round_up(i_size) on inode
+			 * load) can leave a gap inside this range. That gap
+			 * would cause btrfs_inode_safe_disk_i_size_write()
+			 * (via find_contiguous_extent_bit() starting at 0)
+			 * to truncate disk_i_size to the start of the gap,
+			 * making the persisted size smaller than i_size.
+			 */
+			range_start = round_down(inode->i_size, fs_info->sectorsize);
+			range_end = round_up(i_size, fs_info->sectorsize);
+			ret = btrfs_inode_set_file_extent_range(BTRFS_I(inode),
+					range_start, range_end - range_start);
+			if (ret) {
+				btrfs_abort_transaction(trans, ret);
+				if (own_trans)
+					btrfs_end_transaction(trans);
+				break;
+			}
+
+			i_size_write(inode, i_size);
+			btrfs_inode_safe_disk_i_size_write(BTRFS_I(inode), 0);
+		}
+
+		ret = btrfs_update_inode(trans, BTRFS_I(inode));
+
+		if (unlikely(ret)) {
+			btrfs_abort_transaction(trans, ret);
+			if (own_trans)
+				btrfs_end_transaction(trans);
+			break;
+		}
+
+		if (own_trans) {
+			btrfs_end_transaction(trans);
+			trans = NULL;
+		}
+	}
+	if (clear_offset < end)
+		btrfs_free_reserved_data_space(BTRFS_I(inode), NULL, clear_offset,
+			end - clear_offset + 1);
+	return ret;
+}
+
+int btrfs_prealloc_file_range(struct inode *inode, int mode,
+			      u64 start, u64 num_bytes, u64 min_size,
+			      loff_t actual_len, u64 *alloc_hint)
+{
+	return __btrfs_prealloc_file_range(inode, mode, start, num_bytes,
+					   min_size, actual_len, alloc_hint,
+					   NULL);
+}
+
+int btrfs_prealloc_file_range_trans(struct inode *inode,
+				    struct btrfs_trans_handle *trans, int mode,
+				    u64 start, u64 num_bytes, u64 min_size,
+				    loff_t actual_len, u64 *alloc_hint)
+{
+	return __btrfs_prealloc_file_range(inode, mode, start, num_bytes,
+					   min_size, actual_len, alloc_hint, trans);
+}
+
+/*
+ * NOTE: in case you are adding MAY_EXEC check for directories:
+ * we are marking them with IOP_FASTPERM_MAY_EXEC, allowing path lookup to
+ * elide calls here.
+ */
+static int btrfs_permission(struct mnt_idmap *idmap,
+			    struct inode *inode, int mask)
+{
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	umode_t mode = inode->i_mode;
+
+	if (mask & MAY_WRITE &&
+	    (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) {
+		if (btrfs_root_readonly(root))
+			return -EROFS;
+		if (BTRFS_I(inode)->flags & BTRFS_INODE_READONLY)
+			return -EACCES;
+	}
+	return generic_permission(idmap, inode, mask);
+}
+
+static int btrfs_tmpfile(struct mnt_idmap *idmap, struct inode *dir,
+			 struct file *file, umode_t mode)
+{
+	struct btrfs_fs_info *fs_info = inode_to_fs_info(dir);
+	struct btrfs_trans_handle *trans;
+	struct btrfs_root *root = BTRFS_I(dir)->root;
+	struct inode *inode;
+	struct btrfs_new_inode_args new_inode_args = {
+		.dir = dir,
+		.dentry = file->f_path.dentry,
+		.orphan = true,
+	};
+	unsigned int trans_num_items;
+	int ret;
+
+	inode = new_inode(dir->i_sb);
+	if (!inode)
+		return -ENOMEM;
+	inode_init_owner(idmap, inode, dir, mode);
+	inode->i_fop = &btrfs_file_operations;
+	inode->i_op = &btrfs_file_inode_operations;
+	inode->i_mapping->a_ops = &btrfs_aops;
+
+	new_inode_args.inode = inode;
+	ret = btrfs_new_inode_prepare(&new_inode_args, &trans_num_items);
+	if (ret)
+		goto out_inode;
+
+	trans = btrfs_start_transaction(root, trans_num_items);
+	if (IS_ERR(trans)) {
+		ret = PTR_ERR(trans);
+		goto out_new_inode_args;
+	}
+
+	ret = btrfs_create_new_inode(trans, &new_inode_args);
+
+	/*
+	 * We set number of links to 0 in btrfs_create_new_inode(), and here we
+	 * set it to 1 because d_tmpfile() will issue a warning if the count is
+	 * 0, through:
+	 *
+	 *    d_tmpfile() -> inode_dec_link_count() -> drop_nlink()
+	 */
+	set_nlink(inode, 1);
+
+	if (!ret) {
+		d_tmpfile(file, inode);
+		unlock_new_inode(inode);
+		mark_inode_dirty(inode);
+	}
+
+	btrfs_end_transaction(trans);
+	btrfs_btree_balance_dirty(fs_info);
+out_new_inode_args:
+	btrfs_new_inode_args_destroy(&new_inode_args);
+out_inode:
+	if (ret)
+		iput(inode);
+	return finish_open_simple(file, ret);
+}
+
+int btrfs_encoded_io_compression_from_extent(struct btrfs_fs_info *fs_info,
+					     int compress_type)
+{
+	switch (compress_type) {
+	case BTRFS_COMPRESS_NONE:
+		return BTRFS_ENCODED_IO_COMPRESSION_NONE;
+	case BTRFS_COMPRESS_ZLIB:
+		return BTRFS_ENCODED_IO_COMPRESSION_ZLIB;
+	case BTRFS_COMPRESS_LZO:
+		/*
+		 * The LZO format depends on the sector size. 64K is the maximum
+		 * sector size that we support.
+		 */
+		if (fs_info->sectorsize < SZ_4K || fs_info->sectorsize > SZ_64K)
+			return -EINVAL;
+		return BTRFS_ENCODED_IO_COMPRESSION_LZO_4K +
+		       (fs_info->sectorsize_bits - 12);
+	case BTRFS_COMPRESS_ZSTD:
+		return BTRFS_ENCODED_IO_COMPRESSION_ZSTD;
+	default:
+		return -EUCLEAN;
+	}
+}
+
+static ssize_t btrfs_encoded_read_inline(
+				struct kiocb *iocb,
+				struct iov_iter *iter, u64 start,
+				u64 lockend,
+				struct extent_state **cached_state,
+				u64 extent_start, size_t count,
+				struct btrfs_ioctl_encoded_io_args *encoded,
+				bool *unlocked)
+{
+	struct btrfs_inode *inode = BTRFS_I(file_inode(iocb->ki_filp));
+	struct btrfs_root *root = inode->root;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct extent_io_tree *io_tree = &inode->io_tree;
+	BTRFS_PATH_AUTO_FREE(path);
+	struct extent_buffer *leaf;
+	struct btrfs_file_extent_item *item;
+	u64 ram_bytes;
+	unsigned long ptr;
+	void *tmp;
+	ssize_t ret;
+	const bool nowait = (iocb->ki_flags & IOCB_NOWAIT);
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	path->nowait = nowait;
+
+	ret = btrfs_lookup_file_extent(NULL, root, path, btrfs_ino(inode),
+				       extent_start, 0);
+	if (ret) {
+		if (unlikely(ret > 0)) {
+			/* The extent item disappeared? */
+			return -EIO;
+		}
+		return ret;
+	}
+	leaf = path->nodes[0];
+	item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_file_extent_item);
+
+	ram_bytes = btrfs_file_extent_ram_bytes(leaf, item);
+	ptr = btrfs_file_extent_inline_start(item);
+
+	encoded->len = min_t(u64, extent_start + ram_bytes,
+			     inode->vfs_inode.i_size) - iocb->ki_pos;
+	ret = btrfs_encoded_io_compression_from_extent(fs_info,
+				 btrfs_file_extent_compression(leaf, item));
+	if (ret < 0)
+		return ret;
+	encoded->compression = ret;
+	if (encoded->compression) {
+		size_t inline_size;
+
+		inline_size = btrfs_file_extent_inline_item_len(leaf,
+								path->slots[0]);
+		if (inline_size > count)
+			return -ENOBUFS;
+
+		count = inline_size;
+		encoded->unencoded_len = ram_bytes;
+		encoded->unencoded_offset = iocb->ki_pos - extent_start;
+	} else {
+		count = min_t(u64, count, encoded->len);
+		encoded->len = count;
+		encoded->unencoded_len = count;
+		ptr += iocb->ki_pos - extent_start;
+	}
+
+	tmp = kmalloc(count, GFP_NOFS);
+	if (!tmp)
+		return -ENOMEM;
+
+	read_extent_buffer(leaf, tmp, ptr, count);
+	btrfs_release_path(path);
+	btrfs_unlock_extent(io_tree, start, lockend, cached_state);
+	btrfs_inode_unlock(inode, BTRFS_ILOCK_SHARED);
+	*unlocked = true;
+
+	ret = copy_to_iter(tmp, count, iter);
+	if (ret != count)
+		ret = -EFAULT;
+	kfree(tmp);
+
+	return ret;
+}
+
+struct btrfs_encoded_read_private {
+	struct completion *sync_reads;
+	void *uring_ctx;
+	refcount_t pending_refs;
+	blk_status_t status;
+};
+
+static void btrfs_encoded_read_endio(struct btrfs_bio *bbio)
+{
+	struct btrfs_encoded_read_private *priv = bbio->private;
+
+	if (bbio->bio.bi_status) {
+		/*
+		 * The memory barrier implied by the refcount_dec_and_test() here
+		 * pairs with the memory barrier implied by the refcount_dec_and_test()
+		 * in btrfs_encoded_read_regular_fill_pages() to ensure that
+		 * this write is observed before the load of status in
+		 * btrfs_encoded_read_regular_fill_pages().
+		 */
+		WRITE_ONCE(priv->status, bbio->bio.bi_status);
+	}
+	if (refcount_dec_and_test(&priv->pending_refs)) {
+		int err = blk_status_to_errno(READ_ONCE(priv->status));
+
+		if (priv->uring_ctx) {
+			btrfs_uring_read_extent_endio(priv->uring_ctx, err);
+			kfree(priv);
+		} else {
+			complete(priv->sync_reads);
+		}
+	}
+	bio_put(&bbio->bio);
+}
+
+int btrfs_encoded_read_regular_fill_pages(struct btrfs_inode *inode,
+					  u64 disk_bytenr, u64 disk_io_size,
+					  struct page **pages, void *uring_ctx)
+{
+	struct btrfs_encoded_read_private *priv, sync_priv;
+	struct completion sync_reads;
+	unsigned long i = 0;
+	struct btrfs_bio *bbio;
+	int ret;
+
+	/*
+	 * Fast path for synchronous reads which completes in this call, io_uring
+	 * needs longer time span.
+	 */
+	if (uring_ctx) {
+		priv = kmalloc_obj(struct btrfs_encoded_read_private, GFP_NOFS);
+		if (!priv)
+			return -ENOMEM;
+	} else {
+		priv = &sync_priv;
+		init_completion(&sync_reads);
+		priv->sync_reads = &sync_reads;
+	}
+
+	refcount_set(&priv->pending_refs, 1);
+	priv->status = 0;
+	priv->uring_ctx = uring_ctx;
+
+	bbio = btrfs_bio_alloc(BIO_MAX_VECS, REQ_OP_READ, inode, 0,
+			       btrfs_encoded_read_endio, priv);
+	bbio->bio.bi_iter.bi_sector = disk_bytenr >> SECTOR_SHIFT;
+
+	do {
+		size_t bytes = min_t(u64, disk_io_size, PAGE_SIZE);
+
+		if (bio_add_page(&bbio->bio, pages[i], bytes, 0) < bytes) {
+			refcount_inc(&priv->pending_refs);
+			btrfs_submit_bbio(bbio, 0);
+
+			bbio = btrfs_bio_alloc(BIO_MAX_VECS, REQ_OP_READ, inode, 0,
+					       btrfs_encoded_read_endio, priv);
+			bbio->bio.bi_iter.bi_sector = disk_bytenr >> SECTOR_SHIFT;
+			continue;
+		}
+
+		i++;
+		disk_bytenr += bytes;
+		disk_io_size -= bytes;
+	} while (disk_io_size);
+
+	refcount_inc(&priv->pending_refs);
+	btrfs_submit_bbio(bbio, 0);
+
+	if (uring_ctx) {
+		if (refcount_dec_and_test(&priv->pending_refs)) {
+			ret = blk_status_to_errno(READ_ONCE(priv->status));
+			btrfs_uring_read_extent_endio(uring_ctx, ret);
+			kfree(priv);
+			return ret;
+		}
+
+		return -EIOCBQUEUED;
+	} else {
+		if (!refcount_dec_and_test(&priv->pending_refs))
+			wait_for_completion_io(&sync_reads);
+		/* See btrfs_encoded_read_endio() for ordering. */
+		return blk_status_to_errno(READ_ONCE(priv->status));
+	}
+}
+
+ssize_t btrfs_encoded_read_regular(struct kiocb *iocb, struct iov_iter *iter,
+				   u64 start, u64 lockend,
+				   struct extent_state **cached_state,
+				   u64 disk_bytenr, u64 disk_io_size,
+				   size_t count, bool compressed, bool *unlocked)
+{
+	struct btrfs_inode *inode = BTRFS_I(file_inode(iocb->ki_filp));
+	struct extent_io_tree *io_tree = &inode->io_tree;
+	struct page **pages;
+	unsigned long nr_pages, i;
+	u64 cur;
+	size_t page_offset;
+	ssize_t ret;
+
+	nr_pages = DIV_ROUND_UP(disk_io_size, PAGE_SIZE);
+	pages = kzalloc_objs(struct page *, nr_pages, GFP_NOFS);
+	if (!pages)
+		return -ENOMEM;
+	ret = btrfs_alloc_page_array(nr_pages, pages, GFP_NOFS);
+	if (ret) {
+		ret = -ENOMEM;
+		goto out;
+		}
+
+	ret = btrfs_encoded_read_regular_fill_pages(inode, disk_bytenr,
+						    disk_io_size, pages, NULL);
+	if (ret)
+		goto out;
+
+	btrfs_unlock_extent(io_tree, start, lockend, cached_state);
+	btrfs_inode_unlock(inode, BTRFS_ILOCK_SHARED);
+	*unlocked = true;
+
+	if (compressed) {
+		i = 0;
+		page_offset = 0;
+	} else {
+		i = (iocb->ki_pos - start) >> PAGE_SHIFT;
+		page_offset = (iocb->ki_pos - start) & (PAGE_SIZE - 1);
+	}
+	cur = 0;
+	while (cur < count) {
+		size_t bytes = min_t(size_t, count - cur,
+				     PAGE_SIZE - page_offset);
+
+		if (copy_page_to_iter(pages[i], page_offset, bytes,
+				      iter) != bytes) {
+			ret = -EFAULT;
+			goto out;
+		}
+		i++;
+		cur += bytes;
+		page_offset = 0;
+	}
+	ret = count;
+out:
+	for (i = 0; i < nr_pages; i++) {
+		if (pages[i])
+			__free_page(pages[i]);
+	}
+	kfree(pages);
+	return ret;
+}
+
+ssize_t btrfs_encoded_read(struct kiocb *iocb, struct iov_iter *iter,
+			   struct btrfs_ioctl_encoded_io_args *encoded,
+			   struct extent_state **cached_state,
+			   u64 *disk_bytenr, u64 *disk_io_size)
+{
+	struct btrfs_inode *inode = BTRFS_I(file_inode(iocb->ki_filp));
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+	struct extent_io_tree *io_tree = &inode->io_tree;
+	ssize_t ret;
+	size_t count = iov_iter_count(iter);
+	u64 start, lockend;
+	struct extent_map *em;
+	const bool nowait = (iocb->ki_flags & IOCB_NOWAIT);
+	bool unlocked = false;
+
+	file_accessed(iocb->ki_filp);
+
+	ret = btrfs_inode_lock(inode,
+			       BTRFS_ILOCK_SHARED | (nowait ? BTRFS_ILOCK_TRY : 0));
+	if (ret)
+		return ret;
+
+	if (iocb->ki_pos >= inode->vfs_inode.i_size) {
+		btrfs_inode_unlock(inode, BTRFS_ILOCK_SHARED);
+		return 0;
+	}
+	start = ALIGN_DOWN(iocb->ki_pos, fs_info->sectorsize);
+	/*
+	 * We don't know how long the extent containing iocb->ki_pos is, but if
+	 * it's compressed we know that it won't be longer than this.
+	 */
+	lockend = start + BTRFS_MAX_UNCOMPRESSED - 1;
+
+	if (nowait) {
+		struct btrfs_ordered_extent *ordered;
+
+		if (filemap_range_needs_writeback(inode->vfs_inode.i_mapping,
+						  start, lockend)) {
+			ret = -EAGAIN;
+			goto out_unlock_inode;
+		}
+
+		if (!btrfs_try_lock_extent(io_tree, start, lockend, cached_state)) {
+			ret = -EAGAIN;
+			goto out_unlock_inode;
+		}
+
+		ordered = btrfs_lookup_ordered_range(inode, start,
+						     lockend - start + 1);
+		if (ordered) {
+			btrfs_put_ordered_extent(ordered);
+			btrfs_unlock_extent(io_tree, start, lockend, cached_state);
+			ret = -EAGAIN;
+			goto out_unlock_inode;
+		}
+	} else {
+		for (;;) {
+			struct btrfs_ordered_extent *ordered;
+
+			ret = btrfs_wait_ordered_range(inode, start,
+						       lockend - start + 1);
+			if (ret)
+				goto out_unlock_inode;
+
+			btrfs_lock_extent(io_tree, start, lockend, cached_state);
+			ordered = btrfs_lookup_ordered_range(inode, start,
+							     lockend - start + 1);
+			if (!ordered)
+				break;
+			btrfs_put_ordered_extent(ordered);
+			btrfs_unlock_extent(io_tree, start, lockend, cached_state);
+			cond_resched();
+		}
+	}
+
+	em = btrfs_get_extent(inode, NULL, start, lockend - start + 1);
+	if (IS_ERR(em)) {
+		ret = PTR_ERR(em);
+		goto out_unlock_extent;
+	}
+
+	if (em->disk_bytenr == EXTENT_MAP_INLINE) {
+		u64 extent_start = em->start;
+
+		/*
+		 * For inline extents we get everything we need out of the
+		 * extent item.
+		 */
+		btrfs_free_extent_map(em);
+		em = NULL;
+		ret = btrfs_encoded_read_inline(iocb, iter, start, lockend,
+						cached_state, extent_start,
+						count, encoded, &unlocked);
+		goto out_unlock_extent;
+	}
+
+	/*
+	 * We only want to return up to EOF even if the extent extends beyond
+	 * that.
+	 */
+	encoded->len = min_t(u64, btrfs_extent_map_end(em),
+			     inode->vfs_inode.i_size) - iocb->ki_pos;
+	if (em->disk_bytenr == EXTENT_MAP_HOLE ||
+	    (em->flags & EXTENT_FLAG_PREALLOC)) {
+		*disk_bytenr = EXTENT_MAP_HOLE;
+		count = min_t(u64, count, encoded->len);
+		encoded->len = count;
+		encoded->unencoded_len = count;
+	} else if (btrfs_extent_map_is_compressed(em)) {
+		*disk_bytenr = em->disk_bytenr;
+		/*
+		 * Bail if the buffer isn't large enough to return the whole
+		 * compressed extent.
+		 */
+		if (em->disk_num_bytes > count) {
+			ret = -ENOBUFS;
+			goto out_em;
+		}
+		*disk_io_size = em->disk_num_bytes;
+		count = em->disk_num_bytes;
+		encoded->unencoded_len = em->ram_bytes;
+		encoded->unencoded_offset = iocb->ki_pos - (em->start - em->offset);
+		ret = btrfs_encoded_io_compression_from_extent(fs_info,
+					       btrfs_extent_map_compression(em));
+		if (ret < 0)
+			goto out_em;
+		encoded->compression = ret;
+	} else {
+		*disk_bytenr = btrfs_extent_map_block_start(em) + (start - em->start);
+		if (encoded->len > count)
+			encoded->len = count;
+		/*
+		 * Don't read beyond what we locked. This also limits the page
+		 * allocations that we'll do.
+		 */
+		*disk_io_size = min(lockend + 1, iocb->ki_pos + encoded->len) - start;
+		count = start + *disk_io_size - iocb->ki_pos;
+		encoded->len = count;
+		encoded->unencoded_len = count;
+		*disk_io_size = ALIGN(*disk_io_size, fs_info->sectorsize);
+	}
+	btrfs_free_extent_map(em);
+	em = NULL;
+
+	if (*disk_bytenr == EXTENT_MAP_HOLE) {
+		btrfs_unlock_extent(io_tree, start, lockend, cached_state);
+		btrfs_inode_unlock(inode, BTRFS_ILOCK_SHARED);
+		unlocked = true;
+		ret = iov_iter_zero(count, iter);
+		if (ret != count)
+			ret = -EFAULT;
+	} else {
+		ret = -EIOCBQUEUED;
+		goto out_unlock_extent;
+	}
+
+out_em:
+	btrfs_free_extent_map(em);
+out_unlock_extent:
+	/* Leave inode and extent locked if we need to do a read. */
+	if (!unlocked && ret != -EIOCBQUEUED)
+		btrfs_unlock_extent(io_tree, start, lockend, cached_state);
+out_unlock_inode:
+	if (!unlocked && ret != -EIOCBQUEUED)
+		btrfs_inode_unlock(inode, BTRFS_ILOCK_SHARED);
+	return ret;
+}
+
+ssize_t btrfs_do_encoded_write(struct kiocb *iocb, struct iov_iter *from,
+			       const struct btrfs_ioctl_encoded_io_args *encoded)
+{
+	struct btrfs_inode *inode = BTRFS_I(file_inode(iocb->ki_filp));
+	struct btrfs_root *root = inode->root;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct extent_io_tree *io_tree = &inode->io_tree;
+	struct extent_changeset *data_reserved = NULL;
+	struct extent_state *cached_state = NULL;
+	struct btrfs_ordered_extent *ordered;
+	struct btrfs_file_extent file_extent;
+	struct compressed_bio *cb = NULL;
+	int compression;
+	size_t orig_count;
+	const u32 min_folio_size = btrfs_min_folio_size(fs_info);
+	const u32 blocksize = fs_info->sectorsize;
+	u64 start, end;
+	u64 num_bytes, ram_bytes, disk_num_bytes;
+	struct btrfs_key ins;
+	bool extent_reserved = false;
+	struct extent_map *em;
+	ssize_t ret;
+
+	switch (encoded->compression) {
+	case BTRFS_ENCODED_IO_COMPRESSION_ZLIB:
+		compression = BTRFS_COMPRESS_ZLIB;
+		break;
+	case BTRFS_ENCODED_IO_COMPRESSION_ZSTD:
+		compression = BTRFS_COMPRESS_ZSTD;
+		break;
+	case BTRFS_ENCODED_IO_COMPRESSION_LZO_4K:
+	case BTRFS_ENCODED_IO_COMPRESSION_LZO_8K:
+	case BTRFS_ENCODED_IO_COMPRESSION_LZO_16K:
+	case BTRFS_ENCODED_IO_COMPRESSION_LZO_32K:
+	case BTRFS_ENCODED_IO_COMPRESSION_LZO_64K:
+		/* The sector size must match for LZO. */
+		if (encoded->compression -
+		    BTRFS_ENCODED_IO_COMPRESSION_LZO_4K + 12 !=
+		    fs_info->sectorsize_bits)
+			return -EINVAL;
+		compression = BTRFS_COMPRESS_LZO;
+		break;
+	default:
+		return -EINVAL;
+	}
+	if (encoded->encryption != BTRFS_ENCODED_IO_ENCRYPTION_NONE)
+		return -EINVAL;
+
+	/*
+	 * Compressed extents should always have checksums, so error out if we
+	 * have a NOCOW file or inode was created while mounted with NODATASUM.
+	 */
+	if (inode->flags & BTRFS_INODE_NODATASUM)
+		return -EINVAL;
+
+	orig_count = iov_iter_count(from);
+
+	/* The extent size must be sane. */
+	if (encoded->unencoded_len > BTRFS_MAX_UNCOMPRESSED ||
+	    orig_count > BTRFS_MAX_COMPRESSED || orig_count == 0)
+		return -EINVAL;
+
+	/*
+	 * The compressed data must be smaller than the decompressed data.
+	 *
+	 * It's of course possible for data to compress to larger or the same
+	 * size, but the buffered I/O path falls back to no compression for such
+	 * data, and we don't want to break any assumptions by creating these
+	 * extents.
+	 *
+	 * Note that this is less strict than the current check we have that the
+	 * compressed data must be at least one sector smaller than the
+	 * decompressed data. We only want to enforce the weaker requirement
+	 * from old kernels that it is at least one byte smaller.
+	 */
+	if (orig_count >= encoded->unencoded_len)
+		return -EINVAL;
+
+	/* The extent must start on a sector boundary. */
+	start = iocb->ki_pos;
+	if (!IS_ALIGNED(start, fs_info->sectorsize))
+		return -EINVAL;
+
+	/*
+	 * The extent must end on a sector boundary. However, we allow a write
+	 * which ends at or extends i_size to have an unaligned length; we round
+	 * up the extent size and set i_size to the unaligned end.
+	 */
+	if (start + encoded->len < inode->vfs_inode.i_size &&
+	    !IS_ALIGNED(start + encoded->len, fs_info->sectorsize))
+		return -EINVAL;
+
+	/* Finally, the offset in the unencoded data must be sector-aligned. */
+	if (!IS_ALIGNED(encoded->unencoded_offset, fs_info->sectorsize))
+		return -EINVAL;
+
+	num_bytes = ALIGN(encoded->len, fs_info->sectorsize);
+	ram_bytes = ALIGN(encoded->unencoded_len, fs_info->sectorsize);
+	end = start + num_bytes - 1;
+
+	/*
+	 * If the extent cannot be inline, the compressed data on disk must be
+	 * sector-aligned. For convenience, we extend it with zeroes if it
+	 * isn't.
+	 */
+	disk_num_bytes = ALIGN(orig_count, fs_info->sectorsize);
+
+	cb = btrfs_alloc_compressed_write(inode, start, num_bytes);
+	for (int i = 0; i * min_folio_size < disk_num_bytes; i++) {
+		struct folio *folio;
+		size_t bytes = min(min_folio_size, iov_iter_count(from));
+		char *kaddr;
+
+		folio = btrfs_alloc_compr_folio(fs_info, GFP_NOFS);
+		if (!folio) {
+			ret = -ENOMEM;
+			goto out_cb;
+		}
+		kaddr = kmap_local_folio(folio, 0);
+		ret = copy_from_iter(kaddr, bytes, from);
+		kunmap_local(kaddr);
+		if (ret != bytes) {
+			folio_put(folio);
+			ret = -EFAULT;
+			goto out_cb;
+		}
+		if (!IS_ALIGNED(bytes, blocksize))
+			folio_zero_range(folio, bytes, round_up(bytes, blocksize) - bytes);
+		ret = bio_add_folio(&cb->bbio.bio, folio, round_up(bytes, blocksize), 0);
+		if (unlikely(!ret)) {
+			folio_put(folio);
+			ret = -EINVAL;
+			goto out_cb;
+		}
+	}
+	ASSERT(cb->bbio.bio.bi_iter.bi_size == disk_num_bytes);
+
+	for (;;) {
+		ret = btrfs_wait_ordered_range(inode, start, num_bytes);
+		if (ret)
+			goto out_cb;
+		ret = invalidate_inode_pages2_range(inode->vfs_inode.i_mapping,
+						    start >> PAGE_SHIFT,
+						    end >> PAGE_SHIFT);
+		if (ret)
+			goto out_cb;
+		btrfs_lock_extent(io_tree, start, end, &cached_state);
+		ordered = btrfs_lookup_ordered_range(inode, start, num_bytes);
+		if (!ordered &&
+		    !filemap_range_has_page(inode->vfs_inode.i_mapping, start, end))
+			break;
+		if (ordered)
+			btrfs_put_ordered_extent(ordered);
+		btrfs_unlock_extent(io_tree, start, end, &cached_state);
+		cond_resched();
+	}
+
+	/*
+	 * We don't use the higher-level delalloc space functions because our
+	 * num_bytes and disk_num_bytes are different.
+	 */
+	ret = btrfs_alloc_data_chunk_ondemand(inode, disk_num_bytes);
+	if (ret)
+		goto out_unlock;
+	ret = btrfs_qgroup_reserve_data(inode, &data_reserved, start, num_bytes);
+	if (ret)
+		goto out_free_data_space;
+	ret = btrfs_delalloc_reserve_metadata(inode, num_bytes, disk_num_bytes,
+					      false);
+	if (ret)
+		goto out_qgroup_free_data;
+
+	/* Try an inline extent first. */
+	if (encoded->unencoded_len == encoded->len &&
+	    encoded->unencoded_offset == 0 &&
+	    can_cow_file_range_inline(inode, start, encoded->len, orig_count)) {
+		ret = __cow_file_range_inline(inode, encoded->len,
+					      orig_count, compression,
+					      bio_first_folio_all(&cb->bbio.bio),
+					      true);
+		if (ret <= 0) {
+			if (ret == 0)
+				ret = orig_count;
+			goto out_delalloc_release;
+		}
+	}
+
+	ret = btrfs_reserve_extent(root, disk_num_bytes, disk_num_bytes,
+				   disk_num_bytes, 0, 0, &ins, true, true);
+	if (ret)
+		goto out_delalloc_release;
+	extent_reserved = true;
+
+	file_extent.disk_bytenr = ins.objectid;
+	file_extent.disk_num_bytes = ins.offset;
+	file_extent.num_bytes = num_bytes;
+	file_extent.ram_bytes = ram_bytes;
+	file_extent.offset = encoded->unencoded_offset;
+	file_extent.compression = compression;
+	em = btrfs_create_io_em(inode, start, &file_extent, BTRFS_ORDERED_COMPRESSED);
+	if (IS_ERR(em)) {
+		ret = PTR_ERR(em);
+		goto out_free_reserved;
+	}
+	btrfs_free_extent_map(em);
+
+	ordered = btrfs_alloc_ordered_extent(inode, start, &file_extent,
+				       (1U << BTRFS_ORDERED_ENCODED) |
+				       (1U << BTRFS_ORDERED_COMPRESSED));
+	if (IS_ERR(ordered)) {
+		btrfs_drop_extent_map_range(inode, start, end, false);
+		ret = PTR_ERR(ordered);
+		goto out_free_reserved;
+	}
+	btrfs_dec_block_group_reservations(fs_info, ins.objectid);
+
+	if (start + encoded->len > inode->vfs_inode.i_size)
+		i_size_write(&inode->vfs_inode, start + encoded->len);
+
+	btrfs_unlock_extent(io_tree, start, end, &cached_state);
+
+	btrfs_delalloc_release_extents(inode, num_bytes);
+
+	btrfs_submit_compressed_write(ordered, cb);
+	ret = orig_count;
+	goto out;
+
+out_free_reserved:
+	btrfs_dec_block_group_reservations(fs_info, ins.objectid);
+	btrfs_free_reserved_extent(fs_info, ins.objectid, ins.offset, true);
+out_delalloc_release:
+	btrfs_delalloc_release_extents(inode, num_bytes);
+	btrfs_delalloc_release_metadata(inode, disk_num_bytes, ret < 0);
+out_qgroup_free_data:
+	if (ret < 0)
+		btrfs_qgroup_free_data(inode, data_reserved, start, num_bytes, NULL);
+out_free_data_space:
+	/*
+	 * If btrfs_reserve_extent() succeeded, then we already decremented
+	 * bytes_may_use.
+	 */
+	if (!extent_reserved)
+		btrfs_free_reserved_data_space_noquota(inode, disk_num_bytes);
+out_unlock:
+	btrfs_unlock_extent(io_tree, start, end, &cached_state);
+out_cb:
+	if (cb)
+		cleanup_compressed_bio(cb);
+out:
+	extent_changeset_free(data_reserved);
+	if (ret >= 0)
+		iocb->ki_pos += encoded->len;
+	return ret;
+}
+
+#ifdef CONFIG_SWAP
+/*
+ * Add an entry indicating a block group or device which is pinned by a
+ * swapfile. Returns 0 on success, 1 if there is already an entry for it, or a
+ * negative errno on failure.
+ */
+static int btrfs_add_swapfile_pin(struct inode *inode, void *ptr,
+				  bool is_block_group)
+{
+	struct btrfs_fs_info *fs_info = BTRFS_I(inode)->root->fs_info;
+	struct btrfs_swapfile_pin *sp, *entry;
+	struct rb_node **p;
+	struct rb_node *parent = NULL;
+
+	sp = kmalloc_obj(*sp, GFP_NOFS);
+	if (!sp)
+		return -ENOMEM;
+	sp->ptr = ptr;
+	sp->inode = inode;
+	sp->is_block_group = is_block_group;
+	sp->bg_extent_count = 1;
+
+	spin_lock(&fs_info->swapfile_pins_lock);
+	p = &fs_info->swapfile_pins.rb_node;
+	while (*p) {
+		parent = *p;
+		entry = rb_entry(parent, struct btrfs_swapfile_pin, node);
+		if (sp->ptr < entry->ptr ||
+		    (sp->ptr == entry->ptr && sp->inode < entry->inode)) {
+			p = &(*p)->rb_left;
+		} else if (sp->ptr > entry->ptr ||
+			   (sp->ptr == entry->ptr && sp->inode > entry->inode)) {
+			p = &(*p)->rb_right;
+		} else {
+			if (is_block_group)
+				entry->bg_extent_count++;
+			spin_unlock(&fs_info->swapfile_pins_lock);
+			kfree(sp);
+			return 1;
+		}
+	}
+	rb_link_node(&sp->node, parent, p);
+	rb_insert_color(&sp->node, &fs_info->swapfile_pins);
+	spin_unlock(&fs_info->swapfile_pins_lock);
+	return 0;
+}
+
+/* Free all of the entries pinned by this swapfile. */
+static void btrfs_free_swapfile_pins(struct inode *inode)
+{
+	struct btrfs_fs_info *fs_info = BTRFS_I(inode)->root->fs_info;
+	struct btrfs_swapfile_pin *sp;
+	struct rb_node *node, *next;
+	u64 bg_bytes_released = 0;
+	u32 bg_nr_released = 0;
+
+	spin_lock(&fs_info->swapfile_pins_lock);
+	node = rb_first(&fs_info->swapfile_pins);
+	while (node) {
+		next = rb_next(node);
+		sp = rb_entry(node, struct btrfs_swapfile_pin, node);
+		if (sp->inode == inode) {
+			rb_erase(&sp->node, &fs_info->swapfile_pins);
+			if (sp->is_block_group) {
+				struct btrfs_block_group *bg = sp->ptr;
+
+				bg_bytes_released += bg->length;
+				bg_nr_released++;
+				btrfs_dec_block_group_swap_extents(bg,
+							   sp->bg_extent_count);
+				btrfs_put_block_group(bg);
+			}
+			kfree(sp);
+		}
+		node = next;
+	}
+	spin_unlock(&fs_info->swapfile_pins_lock);
+	btrfs_info(fs_info,
+"swapfile deactivated on root %llu ino %llu, released %llu bytes from %u block group(s)",
+		   btrfs_root_id(BTRFS_I(inode)->root),
+		   btrfs_ino(BTRFS_I(inode)), bg_bytes_released,
+		   bg_nr_released);
+}
+
+struct btrfs_swap_info {
+	u64 start;
+	u64 block_start;
+	u64 block_len;
+	u64 lowest_ppage;
+	u64 highest_ppage;
+	unsigned long nr_pages;
+	int nr_extents;
+};
+
+static int btrfs_add_swap_extent(struct swap_info_struct *sis,
+				 struct btrfs_swap_info *bsi)
+{
+	unsigned long nr_pages;
+	unsigned long max_pages;
+	u64 first_ppage, first_ppage_reported, next_ppage;
+	int ret;
+
+	/*
+	 * Our swapfile may have had its size extended after the swap header was
+	 * written. In that case activating the swapfile should not go beyond
+	 * the max size set in the swap header.
+	 */
+	if (bsi->nr_pages >= sis->max)
+		return 0;
+
+	max_pages = sis->max - bsi->nr_pages;
+	first_ppage = PAGE_ALIGN(bsi->block_start) >> PAGE_SHIFT;
+	next_ppage = PAGE_ALIGN_DOWN(bsi->block_start + bsi->block_len) >> PAGE_SHIFT;
+
+	if (first_ppage >= next_ppage)
+		return 0;
+	nr_pages = next_ppage - first_ppage;
+	nr_pages = min(nr_pages, max_pages);
+
+	first_ppage_reported = first_ppage;
+	if (bsi->start == 0)
+		first_ppage_reported++;
+	if (bsi->lowest_ppage > first_ppage_reported)
+		bsi->lowest_ppage = first_ppage_reported;
+	if (bsi->highest_ppage < (next_ppage - 1))
+		bsi->highest_ppage = next_ppage - 1;
+
+	ret = add_swap_extent(sis, bsi->nr_pages, nr_pages, first_ppage);
+	if (ret < 0)
+		return ret;
+	bsi->nr_extents += ret;
+	bsi->nr_pages += nr_pages;
+	return 0;
+}
+
+static void btrfs_swap_deactivate(struct file *file)
+{
+	struct inode *inode = file_inode(file);
+
+	btrfs_free_swapfile_pins(inode);
+	atomic_dec(&BTRFS_I(inode)->root->nr_swapfiles);
+}
+
+static int btrfs_swap_activate(struct swap_info_struct *sis, struct file *file,
+			       sector_t *span)
+{
+	struct inode *inode = file_inode(file);
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
+	struct extent_state *cached_state = NULL;
+	struct btrfs_chunk_map *map = NULL;
+	struct btrfs_device *device = NULL;
+	struct btrfs_swap_info bsi = {
+		.lowest_ppage = (sector_t)-1ULL,
+	};
+	struct btrfs_backref_share_check_ctx *backref_ctx = NULL;
+	struct btrfs_path *path = NULL;
+	int ret = 0;
+	u32 pinned_bg_nr = 0;
+	u64 isize;
+	u64 prev_extent_end = 0;
+	u64 pinned_bg_size = 0;
+
+	/*
+	 * Acquire the inode's mmap lock to prevent races with memory mapped
+	 * writes, as they could happen after we flush delalloc below and before
+	 * we lock the extent range further below. The inode was already locked
+	 * up in the call chain.
+	 */
+	btrfs_assert_inode_locked(BTRFS_I(inode));
+	down_write(&BTRFS_I(inode)->i_mmap_lock);
+
+	/*
+	 * If the swap file was just created, make sure delalloc is done. If the
+	 * file changes again after this, the user is doing something stupid and
+	 * we don't really care.
+	 */
+	ret = btrfs_wait_ordered_range(BTRFS_I(inode), 0, (u64)-1);
+	if (ret)
+		goto out_unlock_mmap;
+
+	/*
+	 * The inode is locked, so these flags won't change after we check them.
+	 */
+	if (BTRFS_I(inode)->flags & BTRFS_INODE_COMPRESS) {
+		btrfs_warn(fs_info, "swapfile must not be compressed");
+		ret = -EINVAL;
+		goto out_unlock_mmap;
+	}
+	if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATACOW)) {
+		btrfs_warn(fs_info, "swapfile must not be copy-on-write");
+		ret = -EINVAL;
+		goto out_unlock_mmap;
+	}
+	if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) {
+		btrfs_warn(fs_info, "swapfile must not be checksummed");
+		ret = -EINVAL;
+		goto out_unlock_mmap;
+	}
+
+	path = btrfs_alloc_path();
+	backref_ctx = btrfs_alloc_backref_share_check_ctx();
+	if (!path || !backref_ctx) {
+		ret = -ENOMEM;
+		goto out_unlock_mmap;
+	}
+
+	/*
+	 * Balance or device remove/replace/resize can move stuff around from
+	 * under us. The exclop protection makes sure they aren't running/won't
+	 * run concurrently while we are mapping the swap extents, and
+	 * fs_info->swapfile_pins prevents them from running while the swap
+	 * file is active and moving the extents. Note that this also prevents
+	 * a concurrent device add which isn't actually necessary, but it's not
+	 * really worth the trouble to allow it.
+	 */
+	if (!btrfs_exclop_start(fs_info, BTRFS_EXCLOP_SWAP_ACTIVATE)) {
+		btrfs_warn(fs_info,
+	   "cannot activate swapfile while exclusive operation is running");
+		ret = -EBUSY;
+		goto out_unlock_mmap;
+	}
+
+	/*
+	 * Prevent snapshot creation while we are activating the swap file.
+	 * We do not want to race with snapshot creation. If snapshot creation
+	 * already started before we bumped nr_swapfiles from 0 to 1 and
+	 * completes before the first write into the swap file after it is
+	 * activated, than that write would fallback to COW.
+	 */
+	if (!btrfs_drew_try_write_lock(&root->snapshot_lock)) {
+		btrfs_exclop_finish(fs_info);
+		btrfs_warn(fs_info,
+	   "cannot activate swapfile because snapshot creation is in progress");
+		ret = -EINVAL;
+		goto out_unlock_mmap;
+	}
+	/*
+	 * Snapshots can create extents which require COW even if NODATACOW is
+	 * set. We use this counter to prevent snapshots. We must increment it
+	 * before walking the extents because we don't want a concurrent
+	 * snapshot to run after we've already checked the extents.
+	 *
+	 * It is possible that subvolume is marked for deletion but still not
+	 * removed yet. To prevent this race, we check the root status before
+	 * activating the swapfile.
+	 */
+	spin_lock(&root->root_item_lock);
+	if (btrfs_root_dead(root)) {
+		spin_unlock(&root->root_item_lock);
+
+		btrfs_drew_write_unlock(&root->snapshot_lock);
+		btrfs_exclop_finish(fs_info);
+		btrfs_warn(fs_info,
+		"cannot activate swapfile because subvolume %llu is being deleted",
+			btrfs_root_id(root));
+		ret = -EPERM;
+		goto out_unlock_mmap;
+	}
+	atomic_inc(&root->nr_swapfiles);
+	spin_unlock(&root->root_item_lock);
+
+	isize = ALIGN_DOWN(inode->i_size, fs_info->sectorsize);
+
+	btrfs_lock_extent(io_tree, 0, isize - 1, &cached_state);
+	while (prev_extent_end < isize) {
+		struct btrfs_key key;
+		struct extent_buffer *leaf;
+		struct btrfs_file_extent_item *ei;
+		struct btrfs_block_group *bg;
+		u64 logical_block_start;
+		u64 physical_block_start;
+		u64 extent_gen;
+		u64 disk_bytenr;
+		u64 len;
+
+		key.objectid = btrfs_ino(BTRFS_I(inode));
+		key.type = BTRFS_EXTENT_DATA_KEY;
+		key.offset = prev_extent_end;
+
+		ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+		if (ret < 0)
+			goto out;
+
+		/*
+		 * If key not found it means we have an implicit hole (NO_HOLES
+		 * is enabled).
+		 */
+		if (ret > 0) {
+			btrfs_warn(fs_info, "swapfile must not have holes");
+			ret = -EINVAL;
+			goto out;
+		}
+
+		leaf = path->nodes[0];
+		ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_file_extent_item);
+
+		if (btrfs_file_extent_type(leaf, ei) == BTRFS_FILE_EXTENT_INLINE) {
+			/*
+			 * It's unlikely we'll ever actually find ourselves
+			 * here, as a file small enough to fit inline won't be
+			 * big enough to store more than the swap header, but in
+			 * case something changes in the future, let's catch it
+			 * here rather than later.
+			 */
+			btrfs_warn(fs_info, "swapfile must not be inline");
+			ret = -EINVAL;
+			goto out;
+		}
+
+		if (btrfs_file_extent_compression(leaf, ei) != BTRFS_COMPRESS_NONE) {
+			btrfs_warn(fs_info, "swapfile must not be compressed");
+			ret = -EINVAL;
+			goto out;
+		}
+
+		disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, ei);
+		if (disk_bytenr == 0) {
+			btrfs_warn(fs_info, "swapfile must not have holes");
+			ret = -EINVAL;
+			goto out;
+		}
+
+		logical_block_start = disk_bytenr + btrfs_file_extent_offset(leaf, ei);
+		extent_gen = btrfs_file_extent_generation(leaf, ei);
+		prev_extent_end = btrfs_file_extent_end(path);
+
+		if (prev_extent_end > isize)
+			len = isize - key.offset;
+		else
+			len = btrfs_file_extent_num_bytes(leaf, ei);
+
+		backref_ctx->curr_leaf_bytenr = leaf->start;
+
+		/*
+		 * Don't need the path anymore, release to avoid deadlocks when
+		 * calling btrfs_is_data_extent_shared() because when joining a
+		 * transaction it can block waiting for the current one's commit
+		 * which in turn may be trying to lock the same leaf to flush
+		 * delayed items for example.
+		 */
+		btrfs_release_path(path);
+
+		ret = btrfs_is_data_extent_shared(BTRFS_I(inode), disk_bytenr,
+						  extent_gen, backref_ctx);
+		if (ret < 0) {
+			goto out;
+		} else if (ret > 0) {
+			btrfs_warn(fs_info,
+				   "swapfile must not be copy-on-write");
+			ret = -EINVAL;
+			goto out;
+		}
+
+		map = btrfs_get_chunk_map(fs_info, logical_block_start, len);
+		if (IS_ERR(map)) {
+			ret = PTR_ERR(map);
+			goto out;
+		}
+
+		if (map->type & BTRFS_BLOCK_GROUP_PROFILE_MASK) {
+			btrfs_warn(fs_info,
+				   "swapfile must have single data profile");
+			ret = -EINVAL;
+			goto out;
+		}
+
+		if (device == NULL) {
+			device = map->stripes[0].dev;
+			ret = btrfs_add_swapfile_pin(inode, device, false);
+			if (ret == 1)
+				ret = 0;
+			else if (ret)
+				goto out;
+		} else if (device != map->stripes[0].dev) {
+			btrfs_warn(fs_info, "swapfile must be on one device");
+			ret = -EINVAL;
+			goto out;
+		}
+
+		physical_block_start = (map->stripes[0].physical +
+					(logical_block_start - map->start));
+		btrfs_free_chunk_map(map);
+		map = NULL;
+
+		bg = btrfs_lookup_block_group(fs_info, logical_block_start);
+		if (!bg) {
+			btrfs_warn(fs_info,
+			   "could not find block group containing swapfile");
+			ret = -EINVAL;
+			goto out;
+		}
+
+		if (!btrfs_inc_block_group_swap_extents(bg)) {
+			btrfs_warn(fs_info,
+			   "block group for swapfile at %llu is read-only%s",
+			   bg->start,
+			   atomic_read(&fs_info->scrubs_running) ?
+				       " (scrub running)" : "");
+			btrfs_put_block_group(bg);
+			ret = -EINVAL;
+			goto out;
+		}
+
+		ret = btrfs_add_swapfile_pin(inode, bg, true);
+		if (ret) {
+			btrfs_put_block_group(bg);
+			if (ret == 1)
+				ret = 0;
+			else
+				goto out;
+		} else {
+			pinned_bg_size += bg->length;
+			pinned_bg_nr++;
+		}
+
+		if (bsi.block_len &&
+		    bsi.block_start + bsi.block_len == physical_block_start) {
+			bsi.block_len += len;
+		} else {
+			if (bsi.block_len) {
+				ret = btrfs_add_swap_extent(sis, &bsi);
+				if (ret)
+					goto out;
+			}
+			bsi.start = key.offset;
+			bsi.block_start = physical_block_start;
+			bsi.block_len = len;
+		}
+
+		if (fatal_signal_pending(current)) {
+			ret = -EINTR;
+			goto out;
+		}
+
+		cond_resched();
+	}
+
+	if (bsi.block_len)
+		ret = btrfs_add_swap_extent(sis, &bsi);
+
+out:
+	if (!IS_ERR_OR_NULL(map))
+		btrfs_free_chunk_map(map);
+
+	btrfs_unlock_extent(io_tree, 0, isize - 1, &cached_state);
+
+	if (ret)
+		btrfs_swap_deactivate(file);
+
+	btrfs_drew_write_unlock(&root->snapshot_lock);
+
+	btrfs_exclop_finish(fs_info);
+
+out_unlock_mmap:
+	up_write(&BTRFS_I(inode)->i_mmap_lock);
+	btrfs_free_backref_share_ctx(backref_ctx);
+	btrfs_free_path(path);
+	if (ret)
+		return ret;
+
+	btrfs_info(fs_info,
+"swapfile activated on root %llu ino %llu, pinned down %llu bytes from %u block group(s)",
+		   btrfs_root_id(BTRFS_I(inode)->root),
+		   btrfs_ino(BTRFS_I(inode)),
+		   pinned_bg_size, pinned_bg_nr);
+	btrfs_warn(fs_info,
+"block groups with swapfile extents will not be scrubbed or balanced");
+
+	if (device)
+		sis->bdev = device->bdev;
+	*span = bsi.highest_ppage - bsi.lowest_ppage + 1;
+	sis->max = bsi.nr_pages;
+	sis->pages = bsi.nr_pages - 1;
+	return bsi.nr_extents;
+}
+#else
+static void btrfs_swap_deactivate(struct file *file)
+{
+}
+
+static int btrfs_swap_activate(struct swap_info_struct *sis, struct file *file,
+			       sector_t *span)
+{
+	return -EOPNOTSUPP;
+}
+#endif
+
+/*
+ * Update the number of bytes used in the VFS' inode. When we replace extents in
+ * a range (clone, dedupe, fallocate's zero range), we must update the number of
+ * bytes used by the inode in an atomic manner, so that concurrent stat(2) calls
+ * always get a correct value.
+ */
+void btrfs_update_inode_bytes(struct btrfs_inode *inode,
+			      const u64 add_bytes,
+			      const u64 del_bytes)
+{
+	if (add_bytes == del_bytes)
+		return;
+
+	spin_lock(&inode->lock);
+	if (del_bytes > 0)
+		inode_sub_bytes(&inode->vfs_inode, del_bytes);
+	if (add_bytes > 0)
+		inode_add_bytes(&inode->vfs_inode, add_bytes);
+	spin_unlock(&inode->lock);
+}
+
+/*
+ * Verify that there are no ordered extents for a given file range.
+ *
+ * @inode:   The target inode.
+ * @start:   Start offset of the file range, should be sector size aligned.
+ * @end:     End offset (inclusive) of the file range, its value +1 should be
+ *           sector size aligned.
+ *
+ * This should typically be used for cases where we locked an inode's VFS lock in
+ * exclusive mode, we have also locked the inode's i_mmap_lock in exclusive mode,
+ * we have flushed all delalloc in the range, we have waited for all ordered
+ * extents in the range to complete and finally we have locked the file range in
+ * the inode's io_tree.
+ */
+void btrfs_assert_inode_range_clean(struct btrfs_inode *inode, u64 start, u64 end)
+{
+	struct btrfs_root *root = inode->root;
+	struct btrfs_ordered_extent *ordered;
+
+	if (!IS_ENABLED(CONFIG_BTRFS_ASSERT))
+		return;
+
+	ordered = btrfs_lookup_first_ordered_range(inode, start, end + 1 - start);
+	if (ordered) {
+		btrfs_err(root->fs_info,
+"found unexpected ordered extent in file range [%llu, %llu] for inode %llu root %llu (ordered range [%llu, %llu])",
+			  start, end, btrfs_ino(inode), btrfs_root_id(root),
+			  ordered->file_offset,
+			  ordered->file_offset + ordered->num_bytes - 1);
+		btrfs_put_ordered_extent(ordered);
+	}
+
+	ASSERT(ordered == NULL);
+}
+
+/*
+ * Find the first inode with a minimum number.
+ *
+ * @root:	The root to search for.
+ * @min_ino:	The minimum inode number.
+ *
+ * Find the first inode in the @root with a number >= @min_ino and return it.
+ * Returns NULL if no such inode found.
+ */
+struct btrfs_inode *btrfs_find_first_inode(struct btrfs_root *root, u64 min_ino)
+{
+	struct btrfs_inode *inode;
+	unsigned long from = min_ino;
+
+	xa_lock(&root->inodes);
+	while (true) {
+		inode = xa_find(&root->inodes, &from, ULONG_MAX, XA_PRESENT);
+		if (!inode)
+			break;
+		if (igrab(&inode->vfs_inode))
+			break;
+
+		from = btrfs_ino(inode) + 1;
+		xa_unlock(&root->inodes);
+		cond_resched();
+		xa_lock(&root->inodes);
+	}
+	xa_unlock(&root->inodes);
+
+	return inode;
+}
+
+static const struct inode_operations btrfs_dir_inode_operations = {
+	.getattr	= btrfs_getattr,
+	.lookup		= btrfs_lookup,
+	.create		= btrfs_create,
+	.unlink		= btrfs_unlink,
+	.link		= btrfs_link,
+	.mkdir		= btrfs_mkdir,
+	.rmdir		= btrfs_rmdir,
+	.rename		= btrfs_rename2,
+	.symlink	= btrfs_symlink,
+	.setattr	= btrfs_setattr,
+	.mknod		= btrfs_mknod,
+	.listxattr	= btrfs_listxattr,
+	.permission	= btrfs_permission,
+	.get_inode_acl	= btrfs_get_acl,
+	.set_acl	= btrfs_set_acl,
+	.update_time	= btrfs_update_time,
+	.tmpfile        = btrfs_tmpfile,
+	.fileattr_get	= btrfs_fileattr_get,
+	.fileattr_set	= btrfs_fileattr_set,
+};
+
+static const struct file_operations btrfs_dir_file_operations = {
+	.llseek		= btrfs_dir_llseek,
+	.read		= generic_read_dir,
+	.iterate_shared	= btrfs_real_readdir,
+	.open		= btrfs_opendir,
+	.unlocked_ioctl	= btrfs_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl	= btrfs_compat_ioctl,
+#endif
+	.release        = btrfs_release_file,
+	.fsync		= btrfs_sync_file,
+	.setlease	= generic_setlease,
+};
+
+/*
+ * The folio is going dirty without a btrfs delalloc space reservation.
+ * This requires a fixup before writeback which we might sleep so cannot
+ * run in this context, so we merely set state on the folio indicating it
+ * needs fixup before writeback.
+ *
+ * Note that there is no range in the input, so the whole folio is marked
+ * dirty and fixup.
+ *
+ * We believe that all callers of dirty_folio either:
+ * - take the folio lock (e.g. pinned folio release notification).
+ * - take the pte lock but must be running on a dirty pte which means
+ *   page_mkwrite() ran on it and reserved the space. zap_pte_range() cannot
+ *   race with writeback cleaning the folio because writeback runs
+ *   folio_mkclean() which also uses the pte lock and revokes outstanding
+ *   writable mappings.
+ * Therefore, an additional folio private lock (a la bfs->lock for all cases,
+ * not just subpage) is not necessary.
+ */
+static bool btrfs_data_dirty_folio(struct address_space *mapping,
+				   struct folio *folio)
+{
+	struct btrfs_inode *inode = BTRFS_I(mapping->host);
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+	const u64 page_start = folio_pos(folio);
+	const u64 range_end = min_t(u64, folio_next_pos(folio),
+				    round_up(i_size_read(&inode->vfs_inode),
+					     fs_info->sectorsize));
+
+	if (range_end > page_start)
+		btrfs_folio_set_fixup_dirty(fs_info, folio, page_start,
+					    range_end - page_start);
+	return filemap_dirty_folio(mapping, folio);
+}
+
+/*
+ * btrfs doesn't support the bmap operation because swapfiles
+ * use bmap to make a mapping of extents in the file.  They assume
+ * these extents won't change over the life of the file and they
+ * use the bmap result to do IO directly to the drive.
+ *
+ * the btrfs bmap call would return logical addresses that aren't
+ * suitable for IO and they also will change frequently as COW
+ * operations happen.  So, swapfile + btrfs == corruption.
+ *
+ * For now we're avoiding this by dropping bmap.
+ */
+static const struct address_space_operations btrfs_aops = {
+	.read_folio	= btrfs_read_folio,
+	.writepages	= btrfs_writepages,
+	.readahead	= btrfs_readahead,
+	.invalidate_folio = btrfs_invalidate_folio,
+	.launder_folio	= btrfs_launder_folio,
+	.release_folio	= btrfs_release_folio,
+	.migrate_folio	= btrfs_migrate_folio,
+	.dirty_folio	= btrfs_data_dirty_folio,
+	.error_remove_folio = generic_error_remove_folio,
+	.swap_activate	= btrfs_swap_activate,
+	.swap_deactivate = btrfs_swap_deactivate,
+};
+
+static const struct inode_operations btrfs_file_inode_operations = {
+	.getattr	= btrfs_getattr,
+	.setattr	= btrfs_setattr,
+	.listxattr      = btrfs_listxattr,
+	.permission	= btrfs_permission,
+	.fiemap		= btrfs_fiemap,
+	.get_inode_acl	= btrfs_get_acl,
+	.set_acl	= btrfs_set_acl,
+	.update_time	= btrfs_update_time,
+	.fileattr_get	= btrfs_fileattr_get,
+	.fileattr_set	= btrfs_fileattr_set,
+};
+static const struct inode_operations btrfs_special_inode_operations = {
+	.getattr	= btrfs_getattr,
+	.setattr	= btrfs_setattr,
+	.permission	= btrfs_permission,
+	.listxattr	= btrfs_listxattr,
+	.get_inode_acl	= btrfs_get_acl,
+	.set_acl	= btrfs_set_acl,
+	.update_time	= btrfs_update_time,
+};
+static const struct inode_operations btrfs_symlink_inode_operations = {
+	.get_link	= page_get_link,
+	.getattr	= btrfs_getattr,
+	.setattr	= btrfs_setattr,
+	.permission	= btrfs_permission,
+	.listxattr	= btrfs_listxattr,
+	.update_time	= btrfs_update_time,
+};
+
+const struct dentry_operations btrfs_dentry_operations = {
+	.d_delete	= btrfs_dentry_delete,
+};