Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 658 insertions, 0 deletions

diff --git a/fs/ext4/move_extent.c b/fs/ext4/move_extent.c
new file mode 100644
index 000000000..3329b7ad5
--- /dev/null
+++ b/fs/ext4/move_extent.c
@@ -0,0 +1,658 @@
+// SPDX-License-Identifier: LGPL-2.1
+/*
+ * Copyright (c) 2008,2009 NEC Software Tohoku, Ltd.
+ * Written by Takashi Sato <t-sato@yk.jp.nec.com>
+ *            Akira Fujita <a-fujita@rs.jp.nec.com>
+ */
+
+#include <linux/fs.h>
+#include <linux/quotaops.h>
+#include <linux/slab.h>
+#include <linux/sched/mm.h>
+#include "ext4_jbd2.h"
+#include "ext4.h"
+#include "ext4_extents.h"
+
+#include <trace/events/ext4.h>
+
+struct mext_data {
+	struct inode *orig_inode;	/* Origin file inode */
+	struct inode *donor_inode;	/* Donor file inode */
+	struct ext4_map_blocks orig_map;/* Origin file's move mapping */
+	ext4_lblk_t donor_lblk;		/* Start block of the donor file */
+};
+
+/**
+ * ext4_double_down_write_data_sem() - write lock two inodes's i_data_sem
+ * @first: inode to be locked
+ * @second: inode to be locked
+ *
+ * Acquire write lock of i_data_sem of the two inodes
+ */
+void
+ext4_double_down_write_data_sem(struct inode *first, struct inode *second)
+{
+	if (first < second) {
+		down_write(&EXT4_I(first)->i_data_sem);
+		down_write_nested(&EXT4_I(second)->i_data_sem, I_DATA_SEM_OTHER);
+	} else {
+		down_write(&EXT4_I(second)->i_data_sem);
+		down_write_nested(&EXT4_I(first)->i_data_sem, I_DATA_SEM_OTHER);
+	}
+}
+
+/**
+ * ext4_double_up_write_data_sem - Release two inodes' write lock of i_data_sem
+ *
+ * @orig_inode:		original inode structure to be released its lock first
+ * @donor_inode:	donor inode structure to be released its lock second
+ * Release write lock of i_data_sem of two inodes (orig and donor).
+ */
+void
+ext4_double_up_write_data_sem(struct inode *orig_inode,
+			      struct inode *donor_inode)
+{
+	up_write(&EXT4_I(orig_inode)->i_data_sem);
+	up_write(&EXT4_I(donor_inode)->i_data_sem);
+}
+
+/* Grab and lock folio on both @inode1 and @inode2 by inode order. */
+static int mext_folio_double_lock(struct inode *inode1, struct inode *inode2,
+				  pgoff_t index1, pgoff_t index2, size_t len,
+				  struct folio *folio[2])
+{
+	struct address_space *mapping[2];
+	unsigned int flags;
+	fgf_t fgp_flags = FGP_WRITEBEGIN;
+
+	BUG_ON(!inode1 || !inode2);
+	if (inode1 < inode2) {
+		mapping[0] = inode1->i_mapping;
+		mapping[1] = inode2->i_mapping;
+	} else {
+		swap(index1, index2);
+		mapping[0] = inode2->i_mapping;
+		mapping[1] = inode1->i_mapping;
+	}
+
+	flags = memalloc_nofs_save();
+	fgp_flags |= fgf_set_order(len);
+	folio[0] = __filemap_get_folio(mapping[0], index1, fgp_flags,
+			mapping_gfp_mask(mapping[0]));
+	if (IS_ERR(folio[0])) {
+		memalloc_nofs_restore(flags);
+		return PTR_ERR(folio[0]);
+	}
+
+	folio[1] = __filemap_get_folio(mapping[1], index2, fgp_flags,
+			mapping_gfp_mask(mapping[1]));
+	memalloc_nofs_restore(flags);
+	if (IS_ERR(folio[1])) {
+		folio_unlock(folio[0]);
+		folio_put(folio[0]);
+		return PTR_ERR(folio[1]);
+	}
+	/*
+	 * __filemap_get_folio() may not wait on folio's writeback if
+	 * BDI not demand that. But it is reasonable to be very conservative
+	 * here and explicitly wait on folio's writeback
+	 */
+	folio_wait_writeback(folio[0]);
+	folio_wait_writeback(folio[1]);
+	if (inode1 > inode2)
+		swap(folio[0], folio[1]);
+
+	return 0;
+}
+
+static void mext_folio_double_unlock(struct folio *folio[2])
+{
+	folio_unlock(folio[0]);
+	folio_put(folio[0]);
+	folio_unlock(folio[1]);
+	folio_put(folio[1]);
+}
+
+/* Force folio buffers uptodate w/o dropping folio's lock */
+static int mext_folio_mkuptodate(struct folio *folio, size_t from, size_t to)
+{
+	struct inode *inode = folio->mapping->host;
+	sector_t block;
+	struct buffer_head *bh, *head;
+	unsigned int blocksize, block_start, block_end;
+	int nr = 0;
+	bool partial = false;
+
+	BUG_ON(!folio_test_locked(folio));
+	BUG_ON(folio_test_writeback(folio));
+
+	if (folio_test_uptodate(folio))
+		return 0;
+
+	blocksize = i_blocksize(inode);
+	head = folio_buffers(folio);
+	if (!head)
+		head = create_empty_buffers(folio, blocksize, 0);
+
+	block = folio_pos(folio) >> inode->i_blkbits;
+	block_end = 0;
+	bh = head;
+	do {
+		block_start = block_end;
+		block_end = block_start + blocksize;
+		if (block_end <= from || block_start >= to) {
+			if (!buffer_uptodate(bh))
+				partial = true;
+			continue;
+		}
+		if (buffer_uptodate(bh))
+			continue;
+		if (!buffer_mapped(bh)) {
+			int err = ext4_get_block(inode, block, bh, 0);
+			if (err)
+				return err;
+			if (!buffer_mapped(bh)) {
+				folio_zero_range(folio, block_start, blocksize);
+				set_buffer_uptodate(bh);
+				continue;
+			}
+		}
+		lock_buffer(bh);
+		if (buffer_uptodate(bh)) {
+			unlock_buffer(bh);
+			continue;
+		}
+		ext4_read_bh_nowait(bh, 0, NULL, false);
+		nr++;
+	} while (block++, (bh = bh->b_this_page) != head);
+
+	/* No io required */
+	if (!nr)
+		goto out;
+
+	bh = head;
+	do {
+		if (bh_offset(bh) + blocksize <= from)
+			continue;
+		if (bh_offset(bh) >= to)
+			break;
+		wait_on_buffer(bh);
+		if (buffer_uptodate(bh))
+			continue;
+		return -EIO;
+	} while ((bh = bh->b_this_page) != head);
+out:
+	if (!partial)
+		folio_mark_uptodate(folio);
+	return 0;
+}
+
+enum mext_move_type {MEXT_SKIP_EXTENT, MEXT_MOVE_EXTENT, MEXT_COPY_DATA};
+
+/*
+ * Start to move extent between the origin inode and the donor inode,
+ * hold one folio for each inode and check the candidate moving extent
+ * mapping status again.
+ */
+static int mext_move_begin(struct mext_data *mext, struct folio *folio[2],
+			   enum mext_move_type *move_type)
+{
+	struct inode *orig_inode = mext->orig_inode;
+	struct inode *donor_inode = mext->donor_inode;
+	unsigned int blkbits = orig_inode->i_blkbits;
+	struct ext4_map_blocks donor_map = {0};
+	loff_t orig_pos, donor_pos;
+	size_t move_len;
+	int ret;
+
+	orig_pos = ((loff_t)mext->orig_map.m_lblk) << blkbits;
+	donor_pos = ((loff_t)mext->donor_lblk) << blkbits;
+	ret = mext_folio_double_lock(orig_inode, donor_inode,
+			orig_pos >> PAGE_SHIFT, donor_pos >> PAGE_SHIFT,
+			((size_t)mext->orig_map.m_len) << blkbits, folio);
+	if (ret)
+		return ret;
+
+	/*
+	 * Check the origin inode's mapping information again under the
+	 * folio lock, as we do not hold the i_data_sem at all times, and
+	 * it may change during the concurrent write-back operation.
+	 */
+	if (mext->orig_map.m_seq != READ_ONCE(EXT4_I(orig_inode)->i_es_seq)) {
+		ret = -ESTALE;
+		goto error;
+	}
+
+	/* Adjust the moving length according to the length of shorter folio. */
+	move_len = umin(folio_next_pos(folio[0]) - orig_pos,
+			folio_next_pos(folio[1]) - donor_pos);
+	move_len >>= blkbits;
+	if (move_len < mext->orig_map.m_len)
+		mext->orig_map.m_len = move_len;
+
+	donor_map.m_lblk = mext->donor_lblk;
+	donor_map.m_len = mext->orig_map.m_len;
+	donor_map.m_flags = 0;
+	ret = ext4_map_blocks(NULL, donor_inode, &donor_map, 0);
+	if (ret < 0)
+		goto error;
+
+	/* Adjust the moving length according to the donor mapping length. */
+	mext->orig_map.m_len = donor_map.m_len;
+
+	/* Skip moving if the donor range is a hole or a delalloc extent. */
+	if (!(donor_map.m_flags & (EXT4_MAP_MAPPED | EXT4_MAP_UNWRITTEN)))
+		*move_type = MEXT_SKIP_EXTENT;
+	/* If both mapping ranges are unwritten, no need to copy data. */
+	else if ((mext->orig_map.m_flags & EXT4_MAP_UNWRITTEN) &&
+		 (donor_map.m_flags & EXT4_MAP_UNWRITTEN))
+		*move_type = MEXT_MOVE_EXTENT;
+	else
+		*move_type = MEXT_COPY_DATA;
+
+	return 0;
+error:
+	mext_folio_double_unlock(folio);
+	return ret;
+}
+
+/*
+ * Re-create the new moved mapping buffers of the original inode and commit
+ * the entire written range.
+ */
+static int mext_folio_mkwrite(struct inode *inode, struct folio *folio,
+			      size_t from, size_t to)
+{
+	unsigned int blocksize = i_blocksize(inode);
+	struct buffer_head *bh, *head;
+	size_t block_start, block_end;
+	sector_t block;
+	int ret;
+
+	head = folio_buffers(folio);
+	if (!head)
+		head = create_empty_buffers(folio, blocksize, 0);
+
+	block = folio_pos(folio) >> inode->i_blkbits;
+	block_end = 0;
+	bh = head;
+	do {
+		block_start = block_end;
+		block_end = block_start + blocksize;
+		if (block_end <= from || block_start >= to)
+			continue;
+
+		ret = ext4_get_block(inode, block, bh, 0);
+		if (ret)
+			return ret;
+	} while (block++, (bh = bh->b_this_page) != head);
+
+	block_commit_write(folio, from, to);
+	return 0;
+}
+
+/*
+ * Save the data in original inode extent blocks and replace one folio size
+ * aligned original inode extent with one or one partial donor inode extent,
+ * and then write out the saved data in new original inode blocks. Pass out
+ * the replaced block count through m_len. Return 0 on success, and an error
+ * code otherwise.
+ */
+static int mext_move_extent(struct mext_data *mext, u64 *m_len)
+{
+	struct inode *orig_inode = mext->orig_inode;
+	struct inode *donor_inode = mext->donor_inode;
+	struct ext4_map_blocks *orig_map = &mext->orig_map;
+	unsigned int blkbits = orig_inode->i_blkbits;
+	struct folio *folio[2] = {NULL, NULL};
+	loff_t from, length;
+	enum mext_move_type move_type = 0;
+	handle_t *handle;
+	u64 r_len = 0;
+	unsigned int credits;
+	int ret, ret2;
+
+	*m_len = 0;
+	trace_ext4_move_extent_enter(orig_inode, orig_map, donor_inode,
+				     mext->donor_lblk);
+	credits = ext4_chunk_trans_extent(orig_inode, 0) * 2;
+	handle = ext4_journal_start(orig_inode, EXT4_HT_MOVE_EXTENTS, credits);
+	if (IS_ERR(handle)) {
+		ret = PTR_ERR(handle);
+		goto out;
+	}
+	ext4_fc_mark_ineligible(orig_inode->i_sb, EXT4_FC_REASON_MOVE_EXT,
+				handle);
+
+	ret = mext_move_begin(mext, folio, &move_type);
+	if (ret)
+		goto stop_handle;
+
+	if (move_type == MEXT_SKIP_EXTENT)
+		goto unlock;
+
+	/*
+	 * Copy the data. First, read the original inode data into the page
+	 * cache. Then, release the existing mapping relationships and swap
+	 * the extent. Finally, re-establish the new mapping relationships
+	 * and dirty the page cache.
+	 */
+	if (move_type == MEXT_COPY_DATA) {
+		from = offset_in_folio(folio[0],
+				((loff_t)orig_map->m_lblk) << blkbits);
+		length = ((loff_t)orig_map->m_len) << blkbits;
+
+		ret = mext_folio_mkuptodate(folio[0], from, from + length);
+		if (ret)
+			goto unlock;
+	}
+
+	if (!filemap_release_folio(folio[0], 0) ||
+	    !filemap_release_folio(folio[1], 0)) {
+		ret = -EBUSY;
+		goto unlock;
+	}
+
+	/* Move extent */
+	ext4_double_down_write_data_sem(orig_inode, donor_inode);
+	*m_len = ext4_swap_extents(handle, orig_inode, donor_inode,
+				   orig_map->m_lblk, mext->donor_lblk,
+				   orig_map->m_len, 1, &ret);
+	ext4_double_up_write_data_sem(orig_inode, donor_inode);
+
+	/* A short-length swap cannot occur after a successful swap extent. */
+	if (WARN_ON_ONCE(!ret && (*m_len != orig_map->m_len)))
+		ret = -EIO;
+
+	if (!(*m_len) || (move_type == MEXT_MOVE_EXTENT))
+		goto unlock;
+
+	/* Copy data */
+	length = (*m_len) << blkbits;
+	ret2 = mext_folio_mkwrite(orig_inode, folio[0], from, from + length);
+	if (ret2) {
+		if (!ret)
+			ret = ret2;
+		goto repair_branches;
+	}
+	/*
+	 * Even in case of data=writeback it is reasonable to pin
+	 * inode to transaction, to prevent unexpected data loss.
+	 */
+	ret2 = ext4_jbd2_inode_add_write(handle, orig_inode,
+			((loff_t)orig_map->m_lblk) << blkbits, length);
+	if (!ret)
+		ret = ret2;
+unlock:
+	mext_folio_double_unlock(folio);
+stop_handle:
+	ext4_journal_stop(handle);
+out:
+	trace_ext4_move_extent_exit(orig_inode, orig_map->m_lblk, donor_inode,
+				    mext->donor_lblk, orig_map->m_len, *m_len,
+				    move_type, ret);
+	return ret;
+
+repair_branches:
+	ret2 = 0;
+	ext4_double_down_write_data_sem(orig_inode, donor_inode);
+	r_len = ext4_swap_extents(handle, donor_inode, orig_inode,
+				  mext->donor_lblk, orig_map->m_lblk,
+				  *m_len, 0, &ret2);
+	ext4_double_up_write_data_sem(orig_inode, donor_inode);
+	if (ret2 || r_len != *m_len) {
+		ext4_error_inode_block(orig_inode, (sector_t)(orig_map->m_lblk),
+				       EIO, "Unable to copy data block, data will be lost!");
+		ret = -EIO;
+	}
+	*m_len = 0;
+	goto unlock;
+}
+
+/*
+ * Check the validity of the basic filesystem environment and the
+ * inodes' support status.
+ */
+static int mext_check_validity(struct inode *orig_inode,
+			       struct inode *donor_inode)
+{
+	struct super_block *sb = orig_inode->i_sb;
+
+	/* origin and donor should be different inodes */
+	if (orig_inode == donor_inode) {
+		ext4_debug("ext4 move extent: The argument files should not be same inode [ino:orig %llu, donor %llu]\n",
+			   orig_inode->i_ino, donor_inode->i_ino);
+		return -EINVAL;
+	}
+
+	/* origin and donor should belone to the same filesystem */
+	if (orig_inode->i_sb != donor_inode->i_sb) {
+		ext4_debug("ext4 move extent: The argument files should be in same FS [ino:orig %llu, donor %llu]\n",
+			   orig_inode->i_ino, donor_inode->i_ino);
+		return -EINVAL;
+	}
+
+	/* Regular file check */
+	if (!S_ISREG(orig_inode->i_mode) || !S_ISREG(donor_inode->i_mode)) {
+		ext4_debug("ext4 move extent: The argument files should be regular file [ino:orig %llu, donor %llu]\n",
+			   orig_inode->i_ino, donor_inode->i_ino);
+		return -EINVAL;
+	}
+
+	if (ext4_has_feature_bigalloc(sb)) {
+		ext4_msg(sb, KERN_ERR,
+			 "Online defrag not supported with bigalloc");
+		return -EOPNOTSUPP;
+	}
+
+	if (IS_DAX(orig_inode)) {
+		ext4_msg(sb, KERN_ERR,
+			 "Online defrag not supported with DAX");
+		return -EOPNOTSUPP;
+	}
+
+	/*
+	 * TODO: it's not obvious how to swap blocks for inodes with full
+	 * journaling enabled.
+	 */
+	if (ext4_should_journal_data(orig_inode) ||
+	    ext4_should_journal_data(donor_inode)) {
+		ext4_msg(sb, KERN_ERR,
+			 "Online defrag not supported with data journaling");
+		return -EOPNOTSUPP;
+	}
+
+	if (IS_ENCRYPTED(orig_inode) || IS_ENCRYPTED(donor_inode)) {
+		ext4_msg(sb, KERN_ERR,
+			 "Online defrag not supported for encrypted files");
+		return -EOPNOTSUPP;
+	}
+
+	/* Ext4 move extent supports only extent based file */
+	if (!(ext4_test_inode_flag(orig_inode, EXT4_INODE_EXTENTS)) ||
+	    !(ext4_test_inode_flag(donor_inode, EXT4_INODE_EXTENTS))) {
+		ext4_msg(sb, KERN_ERR,
+			 "Online defrag not supported for non-extent files");
+		return -EOPNOTSUPP;
+	}
+
+	if (donor_inode->i_mode & (S_ISUID|S_ISGID)) {
+		ext4_debug("ext4 move extent: suid or sgid is set to donor file [ino:orig %llu, donor %llu]\n",
+			   orig_inode->i_ino, donor_inode->i_ino);
+		return -EINVAL;
+	}
+
+	if (IS_IMMUTABLE(donor_inode) || IS_APPEND(donor_inode)) {
+		ext4_debug("ext4 move extent: donor should not be immutable or append file [ino:orig %llu, donor %llu]\n",
+			   orig_inode->i_ino, donor_inode->i_ino);
+		return -EPERM;
+	}
+
+	/* Ext4 move extent does not support swap files */
+	if (IS_SWAPFILE(orig_inode) || IS_SWAPFILE(donor_inode)) {
+		ext4_debug("ext4 move extent: The argument files should not be swap files [ino:orig %llu, donor %llu]\n",
+			   orig_inode->i_ino, donor_inode->i_ino);
+		return -ETXTBSY;
+	}
+
+	if (ext4_is_quota_file(orig_inode) || ext4_is_quota_file(donor_inode)) {
+		ext4_debug("ext4 move extent: The argument files should not be quota files [ino:orig %llu, donor %llu]\n",
+			   orig_inode->i_ino, donor_inode->i_ino);
+		return -EOPNOTSUPP;
+	}
+
+	if ((!orig_inode->i_size) || (!donor_inode->i_size)) {
+		ext4_debug("ext4 move extent: File size is 0 byte\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/*
+ * Check the moving range of ext4_move_extents() whether the files can be
+ * exchanged with each other, and adjust the length to fit within the file
+ * size. Return 0 on success, or a negative error value on failure.
+ */
+static int mext_check_adjust_range(struct inode *orig_inode,
+				   struct inode *donor_inode, __u64 orig_start,
+				   __u64 donor_start, __u64 *len)
+{
+	__u64 orig_eof, donor_eof;
+
+	/* Start offset should be same */
+	if ((orig_start & ~(PAGE_MASK >> orig_inode->i_blkbits)) !=
+	    (donor_start & ~(PAGE_MASK >> orig_inode->i_blkbits))) {
+		ext4_debug("ext4 move extent: orig and donor's start offsets are not aligned [ino:orig %llu, donor %llu]\n",
+			   orig_inode->i_ino, donor_inode->i_ino);
+		return -EINVAL;
+	}
+
+	if ((orig_start >= EXT_MAX_BLOCKS) ||
+	    (donor_start >= EXT_MAX_BLOCKS) ||
+	    (*len > EXT_MAX_BLOCKS) ||
+	    (donor_start + *len >= EXT_MAX_BLOCKS) ||
+	    (orig_start + *len >= EXT_MAX_BLOCKS))  {
+		ext4_debug("ext4 move extent: Can't handle over [%u] blocks [ino:orig %llu, donor %llu]\n",
+			   EXT_MAX_BLOCKS,
+			   orig_inode->i_ino, donor_inode->i_ino);
+		return -EINVAL;
+	}
+
+	orig_eof = EXT4_B_TO_LBLK(orig_inode, i_size_read(orig_inode));
+	donor_eof = EXT4_B_TO_LBLK(donor_inode, i_size_read(donor_inode));
+	if (orig_eof <= orig_start)
+		*len = 0;
+	else if (orig_eof < orig_start + *len - 1)
+		*len = orig_eof - orig_start;
+	if (donor_eof <= donor_start)
+		*len = 0;
+	else if (donor_eof < donor_start + *len - 1)
+		*len = donor_eof - donor_start;
+	if (!*len) {
+		ext4_debug("ext4 move extent: len should not be 0 [ino:orig %llu, donor %llu]\n",
+			   orig_inode->i_ino, donor_inode->i_ino);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/**
+ * ext4_move_extents - Exchange the specified range of a file
+ *
+ * @o_filp:		file structure of the original file
+ * @d_filp:		file structure of the donor file
+ * @orig_blk:		start offset in block for orig
+ * @donor_blk:		start offset in block for donor
+ * @len:		the number of blocks to be moved
+ * @moved_len:		moved block length
+ *
+ * This function returns 0 and moved block length is set in moved_len
+ * if succeed, otherwise returns error value.
+ */
+int ext4_move_extents(struct file *o_filp, struct file *d_filp, __u64 orig_blk,
+		      __u64 donor_blk, __u64 len, __u64 *moved_len)
+{
+	struct inode *orig_inode = file_inode(o_filp);
+	struct inode *donor_inode = file_inode(d_filp);
+	struct mext_data mext;
+	struct super_block *sb = orig_inode->i_sb;
+	struct ext4_sb_info *sbi = EXT4_SB(sb);
+	int retries = 0;
+	u64 m_len;
+	int ret;
+
+	*moved_len = 0;
+
+	/* Protect orig and donor inodes against a truncate */
+	lock_two_nondirectories(orig_inode, donor_inode);
+
+	ret = mext_check_validity(orig_inode, donor_inode);
+	if (ret)
+		goto out;
+
+	/* Wait for all existing dio workers */
+	inode_dio_wait(orig_inode);
+	inode_dio_wait(donor_inode);
+
+	/* Check and adjust the specified move_extent range. */
+	ret = mext_check_adjust_range(orig_inode, donor_inode, orig_blk,
+				      donor_blk, &len);
+	if (ret)
+		goto out;
+
+	mext.orig_inode = orig_inode;
+	mext.donor_inode = donor_inode;
+	while (len) {
+		mext.orig_map.m_lblk = orig_blk;
+		mext.orig_map.m_len = len;
+		mext.orig_map.m_flags = 0;
+		mext.donor_lblk = donor_blk;
+
+		ret = ext4_map_blocks(NULL, orig_inode, &mext.orig_map, 0);
+		if (ret < 0)
+			goto out;
+
+		/* Skip moving if it is a hole or a delalloc extent. */
+		if (mext.orig_map.m_flags &
+		    (EXT4_MAP_MAPPED | EXT4_MAP_UNWRITTEN)) {
+			ret = mext_move_extent(&mext, &m_len);
+			*moved_len += m_len;
+			if (!ret)
+				goto next;
+
+			/* Move failed or partially failed. */
+			if (m_len) {
+				orig_blk += m_len;
+				donor_blk += m_len;
+				len -= m_len;
+			}
+			if (ret == -ESTALE)
+				continue;
+			if (ret == -ENOSPC &&
+			    ext4_should_retry_alloc(sb, &retries))
+				continue;
+			if (ret == -EBUSY &&
+			    sbi->s_journal && retries++ < 4 &&
+			    jbd2_journal_force_commit_nested(sbi->s_journal))
+				continue;
+
+			goto out;
+		}
+next:
+		orig_blk += mext.orig_map.m_len;
+		donor_blk += mext.orig_map.m_len;
+		len -= mext.orig_map.m_len;
+		retries = 0;
+	}
+
+out:
+	if (*moved_len) {
+		ext4_discard_preallocations(orig_inode);
+		ext4_discard_preallocations(donor_inode);
+	}
+
+	unlock_two_nondirectories(orig_inode, donor_inode);
+	return ret;
+}