scftorture: Count single_rpc offline failures in statistics outputgrafted

scf_torture_stats_print() aggregates each invoker thread's counters
into a local scf_statistics structure before printing, but the
n_single_rpc_ofl field is missing from the aggregation loop.  As a
result, the "single_rpc_ofl" value printed in the statistics line is
always zero, even when smp_call_function_single() invocations for the
RPC test have failed due to offline CPUs and been counted by the
invoker threads.

Add the missing accumulation so that the printed value reflects the
actual counts.

Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

7 files changed, 2896 insertions, 0 deletions

diff --git a/fs/zonefs/Kconfig b/fs/zonefs/Kconfig
new file mode 100644
index 000000000..827278f93
--- /dev/null
+++ b/fs/zonefs/Kconfig
@@ -0,0 +1,11 @@
+config ZONEFS_FS
+	tristate "zonefs filesystem support"
+	depends on BLOCK
+	depends on BLK_DEV_ZONED
+	select FS_IOMAP
+	select CRC32
+	help
+	  zonefs is a simple file system which exposes zones of a zoned block
+	  device (e.g. host-managed or host-aware SMR disk drives) as files.
+
+	  If unsure, say N.
diff --git a/fs/zonefs/Makefile b/fs/zonefs/Makefile
new file mode 100644
index 000000000..645f7229d
--- /dev/null
+++ b/fs/zonefs/Makefile
@@ -0,0 +1,6 @@
+# SPDX-License-Identifier: GPL-2.0
+ccflags-y				+= -I$(src)
+
+obj-$(CONFIG_ZONEFS_FS) += zonefs.o
+
+zonefs-y	:= super.o file.o sysfs.o
diff --git a/fs/zonefs/file.c b/fs/zonefs/file.c
new file mode 100644
index 000000000..5ada33f70
--- /dev/null
+++ b/fs/zonefs/file.c
@@ -0,0 +1,873 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Simple file system for zoned block devices exposing zones as files.
+ *
+ * Copyright (C) 2022 Western Digital Corporation or its affiliates.
+ */
+#include <linux/module.h>
+#include <linux/pagemap.h>
+#include <linux/iomap.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/blkdev.h>
+#include <linux/statfs.h>
+#include <linux/writeback.h>
+#include <linux/quotaops.h>
+#include <linux/seq_file.h>
+#include <linux/parser.h>
+#include <linux/uio.h>
+#include <linux/mman.h>
+#include <linux/sched/mm.h>
+#include <linux/task_io_accounting_ops.h>
+
+#include "zonefs.h"
+
+#include "trace.h"
+
+static int zonefs_read_iomap_begin(struct inode *inode, loff_t offset,
+				   loff_t length, unsigned int flags,
+				   struct iomap *iomap, struct iomap *srcmap)
+{
+	struct zonefs_inode_info *zi = ZONEFS_I(inode);
+	struct zonefs_zone *z = zonefs_inode_zone(inode);
+	struct super_block *sb = inode->i_sb;
+	loff_t isize;
+
+	/*
+	 * All blocks are always mapped below EOF. If reading past EOF,
+	 * act as if there is a hole up to the file maximum size.
+	 */
+	mutex_lock(&zi->i_truncate_mutex);
+	iomap->bdev = inode->i_sb->s_bdev;
+	iomap->offset = ALIGN_DOWN(offset, sb->s_blocksize);
+	isize = i_size_read(inode);
+	if (iomap->offset >= isize) {
+		iomap->type = IOMAP_HOLE;
+		iomap->addr = IOMAP_NULL_ADDR;
+		iomap->length = length;
+	} else {
+		iomap->type = IOMAP_MAPPED;
+		iomap->addr = (z->z_sector << SECTOR_SHIFT) + iomap->offset;
+		iomap->length = isize - iomap->offset;
+	}
+	mutex_unlock(&zi->i_truncate_mutex);
+
+	trace_zonefs_iomap_begin(inode, iomap);
+
+	return 0;
+}
+
+static const struct iomap_ops zonefs_read_iomap_ops = {
+	.iomap_begin	= zonefs_read_iomap_begin,
+};
+
+static int zonefs_write_iomap_begin(struct inode *inode, loff_t offset,
+				    loff_t length, unsigned int flags,
+				    struct iomap *iomap, struct iomap *srcmap)
+{
+	struct zonefs_inode_info *zi = ZONEFS_I(inode);
+	struct zonefs_zone *z = zonefs_inode_zone(inode);
+	struct super_block *sb = inode->i_sb;
+	loff_t isize;
+
+	/* All write I/Os should always be within the file maximum size */
+	if (WARN_ON_ONCE(offset + length > z->z_capacity))
+		return -EIO;
+
+	/*
+	 * Sequential zones can only accept direct writes. This is already
+	 * checked when writes are issued, so warn if we see a page writeback
+	 * operation.
+	 */
+	if (WARN_ON_ONCE(zonefs_zone_is_seq(z) && !(flags & IOMAP_DIRECT)))
+		return -EIO;
+
+	/*
+	 * For conventional zones, all blocks are always mapped. For sequential
+	 * zones, all blocks after always mapped below the inode size (zone
+	 * write pointer) and unwritten beyond.
+	 */
+	mutex_lock(&zi->i_truncate_mutex);
+	iomap->bdev = inode->i_sb->s_bdev;
+	iomap->offset = ALIGN_DOWN(offset, sb->s_blocksize);
+	iomap->addr = (z->z_sector << SECTOR_SHIFT) + iomap->offset;
+	isize = i_size_read(inode);
+	if (iomap->offset >= isize) {
+		iomap->type = IOMAP_UNWRITTEN;
+		iomap->length = z->z_capacity - iomap->offset;
+	} else {
+		iomap->type = IOMAP_MAPPED;
+		iomap->length = isize - iomap->offset;
+	}
+	mutex_unlock(&zi->i_truncate_mutex);
+
+	trace_zonefs_iomap_begin(inode, iomap);
+
+	return 0;
+}
+
+static const struct iomap_ops zonefs_write_iomap_ops = {
+	.iomap_begin	= zonefs_write_iomap_begin,
+};
+
+static int zonefs_read_folio(struct file *unused, struct folio *folio)
+{
+	iomap_bio_read_folio(folio, &zonefs_read_iomap_ops);
+	return 0;
+}
+
+static void zonefs_readahead(struct readahead_control *rac)
+{
+	iomap_bio_readahead(rac, &zonefs_read_iomap_ops);
+}
+
+/*
+ * Map blocks for page writeback. This is used only on conventional zone files,
+ * which implies that the page range can only be within the fixed inode size.
+ */
+static ssize_t zonefs_writeback_range(struct iomap_writepage_ctx *wpc,
+		struct folio *folio, u64 offset, unsigned len, u64 end_pos)
+{
+	struct zonefs_zone *z = zonefs_inode_zone(wpc->inode);
+
+	if (WARN_ON_ONCE(zonefs_zone_is_seq(z)))
+		return -EIO;
+	if (WARN_ON_ONCE(offset >= i_size_read(wpc->inode)))
+		return -EIO;
+
+	/* If the mapping is already OK, nothing needs to be done */
+	if (offset < wpc->iomap.offset ||
+	    offset >= wpc->iomap.offset + wpc->iomap.length) {
+		int error;
+
+		error = zonefs_write_iomap_begin(wpc->inode, offset,
+				z->z_capacity - offset, IOMAP_WRITE,
+				&wpc->iomap, NULL);
+		if (error)
+			return error;
+	}
+
+	return iomap_add_to_ioend(wpc, folio, offset, end_pos, len);
+}
+
+static const struct iomap_writeback_ops zonefs_writeback_ops = {
+	.writeback_range	= zonefs_writeback_range,
+	.writeback_submit	= iomap_ioend_writeback_submit,
+};
+
+static int zonefs_writepages(struct address_space *mapping,
+			     struct writeback_control *wbc)
+{
+	struct iomap_writepage_ctx wpc = {
+		.inode		= mapping->host,
+		.wbc		= wbc,
+		.ops		= &zonefs_writeback_ops,
+	};
+
+	return iomap_writepages(&wpc);
+}
+
+static int zonefs_swap_activate(struct swap_info_struct *sis,
+				struct file *swap_file, sector_t *span)
+{
+	struct inode *inode = file_inode(swap_file);
+
+	if (zonefs_inode_is_seq(inode)) {
+		zonefs_err(inode->i_sb,
+			   "swap file: not a conventional zone file\n");
+		return -EINVAL;
+	}
+
+	return iomap_swapfile_activate(sis, swap_file, span,
+				       &zonefs_read_iomap_ops);
+}
+
+const struct address_space_operations zonefs_file_aops = {
+	.read_folio		= zonefs_read_folio,
+	.readahead		= zonefs_readahead,
+	.writepages		= zonefs_writepages,
+	.dirty_folio		= iomap_dirty_folio,
+	.release_folio		= iomap_release_folio,
+	.invalidate_folio	= iomap_invalidate_folio,
+	.migrate_folio		= filemap_migrate_folio,
+	.is_partially_uptodate	= iomap_is_partially_uptodate,
+	.error_remove_folio	= generic_error_remove_folio,
+	.swap_activate		= zonefs_swap_activate,
+};
+
+int zonefs_file_truncate(struct inode *inode, loff_t isize)
+{
+	struct zonefs_inode_info *zi = ZONEFS_I(inode);
+	struct zonefs_zone *z = zonefs_inode_zone(inode);
+	loff_t old_isize;
+	enum req_op op;
+	int ret = 0;
+
+	/*
+	 * Only sequential zone files can be truncated and truncation is allowed
+	 * only down to a 0 size, which is equivalent to a zone reset, and to
+	 * the maximum file size, which is equivalent to a zone finish.
+	 */
+	if (!zonefs_zone_is_seq(z))
+		return -EPERM;
+
+	if (!isize)
+		op = REQ_OP_ZONE_RESET;
+	else if (isize == z->z_capacity)
+		op = REQ_OP_ZONE_FINISH;
+	else
+		return -EPERM;
+
+	inode_dio_wait(inode);
+
+	/* Serialize against page faults */
+	filemap_invalidate_lock(inode->i_mapping);
+
+	/* Serialize against zonefs_iomap_begin() */
+	mutex_lock(&zi->i_truncate_mutex);
+
+	old_isize = i_size_read(inode);
+	if (isize == old_isize)
+		goto unlock;
+
+	ret = zonefs_inode_zone_mgmt(inode, op);
+	if (ret)
+		goto unlock;
+
+	/*
+	 * If the mount option ZONEFS_MNTOPT_EXPLICIT_OPEN is set,
+	 * take care of open zones.
+	 */
+	if (z->z_flags & ZONEFS_ZONE_OPEN) {
+		/*
+		 * Truncating a zone to EMPTY or FULL is the equivalent of
+		 * closing the zone. For a truncation to 0, we need to
+		 * re-open the zone to ensure new writes can be processed.
+		 * For a truncation to the maximum file size, the zone is
+		 * closed and writes cannot be accepted anymore, so clear
+		 * the open flag.
+		 */
+		if (!isize)
+			ret = zonefs_inode_zone_mgmt(inode, REQ_OP_ZONE_OPEN);
+		else
+			z->z_flags &= ~ZONEFS_ZONE_OPEN;
+	}
+
+	zonefs_update_stats(inode, isize);
+	truncate_setsize(inode, isize);
+	z->z_wpoffset = isize;
+	zonefs_inode_account_active(inode);
+
+unlock:
+	mutex_unlock(&zi->i_truncate_mutex);
+	filemap_invalidate_unlock(inode->i_mapping);
+
+	return ret;
+}
+
+static int zonefs_file_fsync(struct file *file, loff_t start, loff_t end,
+			     int datasync)
+{
+	struct inode *inode = file_inode(file);
+	int ret = 0;
+
+	if (unlikely(IS_IMMUTABLE(inode)))
+		return -EPERM;
+
+	/*
+	 * Since only direct writes are allowed in sequential files, page cache
+	 * flush is needed only for conventional zone files.
+	 */
+	if (zonefs_inode_is_cnv(inode))
+		ret = file_write_and_wait_range(file, start, end);
+	if (!ret)
+		ret = blkdev_issue_flush(inode->i_sb->s_bdev);
+
+	if (ret)
+		zonefs_io_error(inode, true);
+
+	return ret;
+}
+
+static vm_fault_t zonefs_filemap_page_mkwrite(struct vm_fault *vmf)
+{
+	struct inode *inode = file_inode(vmf->vma->vm_file);
+	vm_fault_t ret;
+
+	if (unlikely(IS_IMMUTABLE(inode)))
+		return VM_FAULT_SIGBUS;
+
+	/*
+	 * Sanity check: only conventional zone files can have shared
+	 * writeable mappings.
+	 */
+	if (zonefs_inode_is_seq(inode))
+		return VM_FAULT_NOPAGE;
+
+	sb_start_pagefault(inode->i_sb);
+	file_update_time(vmf->vma->vm_file);
+
+	/* Serialize against truncates */
+	filemap_invalidate_lock_shared(inode->i_mapping);
+	ret = iomap_page_mkwrite(vmf, &zonefs_write_iomap_ops, NULL);
+	filemap_invalidate_unlock_shared(inode->i_mapping);
+
+	sb_end_pagefault(inode->i_sb);
+	return ret;
+}
+
+static const struct vm_operations_struct zonefs_file_vm_ops = {
+	.fault		= filemap_fault,
+	.map_pages	= filemap_map_pages,
+	.page_mkwrite	= zonefs_filemap_page_mkwrite,
+};
+
+static int zonefs_file_mmap_prepare(struct vm_area_desc *desc)
+{
+	struct file *file = desc->file;
+
+	/*
+	 * Conventional zones accept random writes, so their files can support
+	 * shared writable mappings. For sequential zone files, only read
+	 * mappings are possible since there are no guarantees for write
+	 * ordering between msync() and page cache writeback.
+	 */
+	if (zonefs_inode_is_seq(file_inode(file)) &&
+	    vma_desc_test_all(desc, VMA_SHARED_BIT, VMA_MAYWRITE_BIT))
+		return -EINVAL;
+
+	file_accessed(file);
+	desc->vm_ops = &zonefs_file_vm_ops;
+
+	return 0;
+}
+
+static loff_t zonefs_file_llseek(struct file *file, loff_t offset, int whence)
+{
+	loff_t isize = i_size_read(file_inode(file));
+
+	/*
+	 * Seeks are limited to below the zone size for conventional zones
+	 * and below the zone write pointer for sequential zones. In both
+	 * cases, this limit is the inode size.
+	 */
+	return generic_file_llseek_size(file, offset, whence, isize, isize);
+}
+
+static int zonefs_file_write_dio_end_io(struct kiocb *iocb, ssize_t size,
+					int error, unsigned int flags)
+{
+	struct inode *inode = file_inode(iocb->ki_filp);
+	struct zonefs_inode_info *zi = ZONEFS_I(inode);
+
+	if (error) {
+		/*
+		 * For Sync IOs, error recovery is called from
+		 * zonefs_file_dio_write().
+		 */
+		if (!is_sync_kiocb(iocb))
+			zonefs_io_error(inode, true);
+		return error;
+	}
+
+	if (size && zonefs_inode_is_seq(inode)) {
+		/*
+		 * Note that we may be seeing completions out of order,
+		 * but that is not a problem since a write completed
+		 * successfully necessarily means that all preceding writes
+		 * were also successful. So we can safely increase the inode
+		 * size to the write end location.
+		 */
+		mutex_lock(&zi->i_truncate_mutex);
+		if (i_size_read(inode) < iocb->ki_pos + size) {
+			zonefs_update_stats(inode, iocb->ki_pos + size);
+			zonefs_i_size_write(inode, iocb->ki_pos + size);
+		}
+		mutex_unlock(&zi->i_truncate_mutex);
+	}
+
+	return 0;
+}
+
+static const struct iomap_dio_ops zonefs_write_dio_ops = {
+	.end_io		= zonefs_file_write_dio_end_io,
+};
+
+/*
+ * Do not exceed the LFS limits nor the file zone size. If pos is under the
+ * limit it becomes a short access. If it exceeds the limit, return -EFBIG.
+ */
+static loff_t zonefs_write_check_limits(struct file *file, loff_t pos,
+					loff_t count)
+{
+	struct inode *inode = file_inode(file);
+	struct zonefs_zone *z = zonefs_inode_zone(inode);
+	loff_t limit = rlimit(RLIMIT_FSIZE);
+	loff_t max_size = z->z_capacity;
+
+	if (limit != RLIM_INFINITY) {
+		if (pos >= limit) {
+			send_sig(SIGXFSZ, current, 0);
+			return -EFBIG;
+		}
+		count = min(count, limit - pos);
+	}
+
+	if (!(file->f_flags & O_LARGEFILE))
+		max_size = min_t(loff_t, MAX_NON_LFS, max_size);
+
+	if (unlikely(pos >= max_size))
+		return -EFBIG;
+
+	return min(count, max_size - pos);
+}
+
+static ssize_t zonefs_write_checks(struct kiocb *iocb, struct iov_iter *from)
+{
+	struct file *file = iocb->ki_filp;
+	struct inode *inode = file_inode(file);
+	struct zonefs_inode_info *zi = ZONEFS_I(inode);
+	struct zonefs_zone *z = zonefs_inode_zone(inode);
+	loff_t count;
+
+	if (IS_SWAPFILE(inode))
+		return -ETXTBSY;
+
+	if (!iov_iter_count(from))
+		return 0;
+
+	if ((iocb->ki_flags & IOCB_NOWAIT) && !(iocb->ki_flags & IOCB_DIRECT))
+		return -EINVAL;
+
+	if (iocb->ki_flags & IOCB_APPEND) {
+		if (zonefs_zone_is_cnv(z))
+			return -EINVAL;
+		mutex_lock(&zi->i_truncate_mutex);
+		iocb->ki_pos = z->z_wpoffset;
+		mutex_unlock(&zi->i_truncate_mutex);
+	}
+
+	count = zonefs_write_check_limits(file, iocb->ki_pos,
+					  iov_iter_count(from));
+	if (count < 0)
+		return count;
+
+	iov_iter_truncate(from, count);
+	return iov_iter_count(from);
+}
+
+/*
+ * Handle direct writes. For sequential zone files, this is the only possible
+ * write path. For these files, check that the user is issuing writes
+ * sequentially from the end of the file. This code assumes that the block layer
+ * delivers write requests to the device in sequential order. This is always the
+ * case if a block IO scheduler implementing the ELEVATOR_F_ZBD_SEQ_WRITE
+ * elevator feature is being used (e.g. mq-deadline). The block layer always
+ * automatically select such an elevator for zoned block devices during the
+ * device initialization.
+ */
+static ssize_t zonefs_file_dio_write(struct kiocb *iocb, struct iov_iter *from)
+{
+	struct inode *inode = file_inode(iocb->ki_filp);
+	struct zonefs_inode_info *zi = ZONEFS_I(inode);
+	struct zonefs_zone *z = zonefs_inode_zone(inode);
+	struct super_block *sb = inode->i_sb;
+	ssize_t ret, count;
+
+	/*
+	 * For async direct IOs to sequential zone files, refuse IOCB_NOWAIT
+	 * as this can cause write reordering (e.g. the first aio gets EAGAIN
+	 * on the inode lock but the second goes through but is now unaligned).
+	 */
+	if (zonefs_zone_is_seq(z) && !is_sync_kiocb(iocb) &&
+	    (iocb->ki_flags & IOCB_NOWAIT))
+		return -EOPNOTSUPP;
+
+	if (iocb->ki_flags & IOCB_NOWAIT) {
+		if (!inode_trylock(inode))
+			return -EAGAIN;
+	} else {
+		inode_lock(inode);
+	}
+
+	count = zonefs_write_checks(iocb, from);
+	if (count <= 0) {
+		ret = count;
+		goto inode_unlock;
+	}
+
+	if ((iocb->ki_pos | count) & (sb->s_blocksize - 1)) {
+		ret = -EINVAL;
+		goto inode_unlock;
+	}
+
+	/* Enforce sequential writes (append only) in sequential zones */
+	if (zonefs_zone_is_seq(z)) {
+		mutex_lock(&zi->i_truncate_mutex);
+		if (iocb->ki_pos != z->z_wpoffset) {
+			mutex_unlock(&zi->i_truncate_mutex);
+			ret = -EINVAL;
+			goto inode_unlock;
+		}
+		/*
+		 * Advance the zone write pointer offset. This assumes that the
+		 * IO will succeed, which is OK to do because we do not allow
+		 * partial writes (IOMAP_DIO_PARTIAL is not set) and if the IO
+		 * fails, the error path will correct the write pointer offset.
+		 */
+		z->z_wpoffset += count;
+		zonefs_inode_account_active(inode);
+		mutex_unlock(&zi->i_truncate_mutex);
+	}
+
+	/*
+	 * iomap_dio_rw() may return ENOTBLK if there was an issue with
+	 * page invalidation. Overwrite that error code with EBUSY so that
+	 * the user can make sense of the error.
+	 */
+	ret = iomap_dio_rw(iocb, from, &zonefs_write_iomap_ops,
+			   &zonefs_write_dio_ops, 0, NULL, 0);
+	if (ret == -ENOTBLK)
+		ret = -EBUSY;
+
+	/*
+	 * For a failed IO or partial completion, trigger error recovery
+	 * to update the zone write pointer offset to a correct value.
+	 * For asynchronous IOs, zonefs_file_write_dio_end_io() may already
+	 * have executed error recovery if the IO already completed when we
+	 * reach here. However, we cannot know that and execute error recovery
+	 * again (that will not change anything).
+	 */
+	if (zonefs_zone_is_seq(z)) {
+		if (ret > 0 && ret != count)
+			ret = -EIO;
+		if (ret < 0 && ret != -EIOCBQUEUED)
+			zonefs_io_error(inode, true);
+	}
+
+inode_unlock:
+	inode_unlock(inode);
+
+	return ret;
+}
+
+static ssize_t zonefs_file_buffered_write(struct kiocb *iocb,
+					  struct iov_iter *from)
+{
+	struct inode *inode = file_inode(iocb->ki_filp);
+	ssize_t ret;
+
+	/*
+	 * Direct IO writes are mandatory for sequential zone files so that the
+	 * write IO issuing order is preserved.
+	 */
+	if (zonefs_inode_is_seq(inode))
+		return -EIO;
+
+	if (iocb->ki_flags & IOCB_NOWAIT) {
+		if (!inode_trylock(inode))
+			return -EAGAIN;
+	} else {
+		inode_lock(inode);
+	}
+
+	ret = zonefs_write_checks(iocb, from);
+	if (ret <= 0)
+		goto inode_unlock;
+
+	ret = iomap_file_buffered_write(iocb, from, &zonefs_write_iomap_ops,
+			NULL, NULL);
+	if (ret == -EIO)
+		zonefs_io_error(inode, true);
+
+inode_unlock:
+	inode_unlock(inode);
+	if (ret > 0)
+		ret = generic_write_sync(iocb, ret);
+
+	return ret;
+}
+
+static ssize_t zonefs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
+{
+	struct inode *inode = file_inode(iocb->ki_filp);
+	struct zonefs_zone *z = zonefs_inode_zone(inode);
+
+	if (unlikely(IS_IMMUTABLE(inode)))
+		return -EPERM;
+
+	if (sb_rdonly(inode->i_sb))
+		return -EROFS;
+
+	/* Write operations beyond the zone capacity are not allowed */
+	if (iocb->ki_pos >= z->z_capacity)
+		return -EFBIG;
+
+	if (iocb->ki_flags & IOCB_DIRECT) {
+		ssize_t ret = zonefs_file_dio_write(iocb, from);
+
+		if (ret != -ENOTBLK)
+			return ret;
+	}
+
+	return zonefs_file_buffered_write(iocb, from);
+}
+
+static int zonefs_file_read_dio_end_io(struct kiocb *iocb, ssize_t size,
+				       int error, unsigned int flags)
+{
+	if (error) {
+		zonefs_io_error(file_inode(iocb->ki_filp), false);
+		return error;
+	}
+
+	return 0;
+}
+
+static const struct iomap_dio_ops zonefs_read_dio_ops = {
+	.end_io			= zonefs_file_read_dio_end_io,
+};
+
+static ssize_t zonefs_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
+{
+	struct inode *inode = file_inode(iocb->ki_filp);
+	struct zonefs_inode_info *zi = ZONEFS_I(inode);
+	struct zonefs_zone *z = zonefs_inode_zone(inode);
+	struct super_block *sb = inode->i_sb;
+	loff_t isize;
+	ssize_t ret;
+
+	/* Offline zones cannot be read */
+	if (unlikely(IS_IMMUTABLE(inode) && !(inode->i_mode & 0777)))
+		return -EPERM;
+
+	if (iocb->ki_pos >= z->z_capacity)
+		return 0;
+
+	if (iocb->ki_flags & IOCB_NOWAIT) {
+		if (!inode_trylock_shared(inode))
+			return -EAGAIN;
+	} else {
+		inode_lock_shared(inode);
+	}
+
+	/* Limit read operations to written data */
+	mutex_lock(&zi->i_truncate_mutex);
+	isize = i_size_read(inode);
+	if (iocb->ki_pos >= isize) {
+		mutex_unlock(&zi->i_truncate_mutex);
+		ret = 0;
+		goto inode_unlock;
+	}
+	iov_iter_truncate(to, isize - iocb->ki_pos);
+	mutex_unlock(&zi->i_truncate_mutex);
+
+	if (iocb->ki_flags & IOCB_DIRECT) {
+		size_t count = iov_iter_count(to);
+
+		if ((iocb->ki_pos | count) & (sb->s_blocksize - 1)) {
+			ret = -EINVAL;
+			goto inode_unlock;
+		}
+		file_accessed(iocb->ki_filp);
+		ret = iomap_dio_rw(iocb, to, &zonefs_read_iomap_ops,
+				   &zonefs_read_dio_ops, 0, NULL, 0);
+	} else {
+		ret = generic_file_read_iter(iocb, to);
+		if (ret == -EIO)
+			zonefs_io_error(inode, false);
+	}
+
+inode_unlock:
+	inode_unlock_shared(inode);
+
+	return ret;
+}
+
+static ssize_t zonefs_file_splice_read(struct file *in, loff_t *ppos,
+				       struct pipe_inode_info *pipe,
+				       size_t len, unsigned int flags)
+{
+	struct inode *inode = file_inode(in);
+	struct zonefs_inode_info *zi = ZONEFS_I(inode);
+	struct zonefs_zone *z = zonefs_inode_zone(inode);
+	loff_t isize;
+	ssize_t ret = 0;
+
+	/* Offline zones cannot be read */
+	if (unlikely(IS_IMMUTABLE(inode) && !(inode->i_mode & 0777)))
+		return -EPERM;
+
+	if (*ppos >= z->z_capacity)
+		return 0;
+
+	inode_lock_shared(inode);
+
+	/* Limit read operations to written data */
+	mutex_lock(&zi->i_truncate_mutex);
+	isize = i_size_read(inode);
+	if (*ppos >= isize)
+		len = 0;
+	else
+		len = min_t(loff_t, len, isize - *ppos);
+	mutex_unlock(&zi->i_truncate_mutex);
+
+	if (len > 0) {
+		ret = filemap_splice_read(in, ppos, pipe, len, flags);
+		if (ret == -EIO)
+			zonefs_io_error(inode, false);
+	}
+
+	inode_unlock_shared(inode);
+	return ret;
+}
+
+/*
+ * Write open accounting is done only for sequential files.
+ */
+static inline bool zonefs_seq_file_need_wro(struct inode *inode,
+					    struct file *file)
+{
+	if (zonefs_inode_is_cnv(inode))
+		return false;
+
+	if (!(file->f_mode & FMODE_WRITE))
+		return false;
+
+	return true;
+}
+
+static int zonefs_seq_file_write_open(struct inode *inode)
+{
+	struct zonefs_inode_info *zi = ZONEFS_I(inode);
+	struct zonefs_zone *z = zonefs_inode_zone(inode);
+	int ret = 0;
+
+	mutex_lock(&zi->i_truncate_mutex);
+
+	if (!zi->i_wr_refcnt) {
+		struct zonefs_sb_info *sbi = ZONEFS_SB(inode->i_sb);
+		unsigned int wro = atomic_inc_return(&sbi->s_wro_seq_files);
+
+		if (sbi->s_mount_opts & ZONEFS_MNTOPT_EXPLICIT_OPEN) {
+
+			if (sbi->s_max_wro_seq_files
+			    && wro > sbi->s_max_wro_seq_files) {
+				atomic_dec(&sbi->s_wro_seq_files);
+				ret = -EBUSY;
+				goto unlock;
+			}
+
+			if (i_size_read(inode) < z->z_capacity) {
+				ret = zonefs_inode_zone_mgmt(inode,
+							     REQ_OP_ZONE_OPEN);
+				if (ret) {
+					atomic_dec(&sbi->s_wro_seq_files);
+					goto unlock;
+				}
+				z->z_flags |= ZONEFS_ZONE_OPEN;
+				zonefs_inode_account_active(inode);
+			}
+		}
+	}
+
+	zi->i_wr_refcnt++;
+
+unlock:
+	mutex_unlock(&zi->i_truncate_mutex);
+
+	return ret;
+}
+
+static int zonefs_file_open(struct inode *inode, struct file *file)
+{
+	int ret;
+
+	file->f_mode |= FMODE_CAN_ODIRECT;
+	ret = generic_file_open(inode, file);
+	if (ret)
+		return ret;
+
+	if (zonefs_seq_file_need_wro(inode, file))
+		return zonefs_seq_file_write_open(inode);
+
+	return 0;
+}
+
+static void zonefs_seq_file_write_close(struct inode *inode)
+{
+	struct zonefs_inode_info *zi = ZONEFS_I(inode);
+	struct zonefs_zone *z = zonefs_inode_zone(inode);
+	struct super_block *sb = inode->i_sb;
+	struct zonefs_sb_info *sbi = ZONEFS_SB(sb);
+	int ret = 0;
+
+	mutex_lock(&zi->i_truncate_mutex);
+
+	zi->i_wr_refcnt--;
+	if (zi->i_wr_refcnt)
+		goto unlock;
+
+	/*
+	 * The file zone may not be open anymore (e.g. the file was truncated to
+	 * its maximum size or it was fully written). For this case, we only
+	 * need to decrement the write open count.
+	 */
+	if (z->z_flags & ZONEFS_ZONE_OPEN) {
+		ret = zonefs_inode_zone_mgmt(inode, REQ_OP_ZONE_CLOSE);
+		if (ret) {
+			__zonefs_io_error(inode, false);
+			/*
+			 * Leaving zones explicitly open may lead to a state
+			 * where most zones cannot be written (zone resources
+			 * exhausted). So take preventive action by remounting
+			 * read-only.
+			 */
+			if (z->z_flags & ZONEFS_ZONE_OPEN &&
+			    !(sb->s_flags & SB_RDONLY)) {
+				zonefs_warn(sb,
+					"closing zone at %llu failed %d\n",
+					z->z_sector, ret);
+				zonefs_warn(sb,
+					"remounting filesystem read-only\n");
+				sb->s_flags |= SB_RDONLY;
+			}
+			goto unlock;
+		}
+
+		z->z_flags &= ~ZONEFS_ZONE_OPEN;
+		zonefs_inode_account_active(inode);
+	}
+
+	atomic_dec(&sbi->s_wro_seq_files);
+
+unlock:
+	mutex_unlock(&zi->i_truncate_mutex);
+}
+
+static int zonefs_file_release(struct inode *inode, struct file *file)
+{
+	/*
+	 * If we explicitly open a zone we must close it again as well, but the
+	 * zone management operation can fail (either due to an IO error or as
+	 * the zone has gone offline or read-only). Make sure we don't fail the
+	 * close(2) for user-space.
+	 */
+	if (zonefs_seq_file_need_wro(inode, file))
+		zonefs_seq_file_write_close(inode);
+
+	return 0;
+}
+
+const struct file_operations zonefs_file_operations = {
+	.open		= zonefs_file_open,
+	.release	= zonefs_file_release,
+	.fsync		= zonefs_file_fsync,
+	.mmap_prepare	= zonefs_file_mmap_prepare,
+	.llseek		= zonefs_file_llseek,
+	.read_iter	= zonefs_file_read_iter,
+	.write_iter	= zonefs_file_write_iter,
+	.splice_read	= zonefs_file_splice_read,
+	.splice_write	= iter_file_splice_write,
+	.iopoll		= iocb_bio_iopoll,
+};
diff --git a/fs/zonefs/super.c b/fs/zonefs/super.c
new file mode 100644
index 000000000..ff43d6d1e
--- /dev/null
+++ b/fs/zonefs/super.c
@@ -0,0 +1,1476 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Simple file system for zoned block devices exposing zones as files.
+ *
+ * Copyright (C) 2019 Western Digital Corporation or its affiliates.
+ */
+#include <linux/module.h>
+#include <linux/pagemap.h>
+#include <linux/magic.h>
+#include <linux/iomap.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/blkdev.h>
+#include <linux/statfs.h>
+#include <linux/writeback.h>
+#include <linux/quotaops.h>
+#include <linux/seq_file.h>
+#include <linux/uio.h>
+#include <linux/mman.h>
+#include <linux/sched/mm.h>
+#include <linux/crc32.h>
+#include <linux/task_io_accounting_ops.h>
+#include <linux/fs_parser.h>
+#include <linux/fs_context.h>
+
+#include "zonefs.h"
+
+#define CREATE_TRACE_POINTS
+#include "trace.h"
+
+/*
+ * Get the name of a zone group directory.
+ */
+static const char *zonefs_zgroup_name(enum zonefs_ztype ztype)
+{
+	switch (ztype) {
+	case ZONEFS_ZTYPE_CNV:
+		return "cnv";
+	case ZONEFS_ZTYPE_SEQ:
+		return "seq";
+	default:
+		WARN_ON_ONCE(1);
+		return "???";
+	}
+}
+
+/*
+ * Manage the active zone count.
+ */
+static void zonefs_account_active(struct super_block *sb,
+				  struct zonefs_zone *z)
+{
+	struct zonefs_sb_info *sbi = ZONEFS_SB(sb);
+
+	if (zonefs_zone_is_cnv(z))
+		return;
+
+	/*
+	 * For zones that transitioned to the offline or readonly condition,
+	 * we only need to clear the active state.
+	 */
+	if (z->z_flags & (ZONEFS_ZONE_OFFLINE | ZONEFS_ZONE_READONLY))
+		goto out;
+
+	/*
+	 * If the zone is active, that is, if it is explicitly open or
+	 * partially written, check if it was already accounted as active.
+	 */
+	if ((z->z_flags & ZONEFS_ZONE_OPEN) ||
+	    (z->z_wpoffset > 0 && z->z_wpoffset < z->z_capacity)) {
+		if (!(z->z_flags & ZONEFS_ZONE_ACTIVE)) {
+			z->z_flags |= ZONEFS_ZONE_ACTIVE;
+			atomic_inc(&sbi->s_active_seq_files);
+		}
+		return;
+	}
+
+out:
+	/* The zone is not active. If it was, update the active count */
+	if (z->z_flags & ZONEFS_ZONE_ACTIVE) {
+		z->z_flags &= ~ZONEFS_ZONE_ACTIVE;
+		atomic_dec(&sbi->s_active_seq_files);
+	}
+}
+
+/*
+ * Manage the active zone count. Called with zi->i_truncate_mutex held.
+ */
+void zonefs_inode_account_active(struct inode *inode)
+{
+	lockdep_assert_held(&ZONEFS_I(inode)->i_truncate_mutex);
+
+	return zonefs_account_active(inode->i_sb, zonefs_inode_zone(inode));
+}
+
+/*
+ * Execute a zone management operation.
+ */
+static int zonefs_zone_mgmt(struct super_block *sb,
+			    struct zonefs_zone *z, enum req_op op)
+{
+	int ret;
+
+	/*
+	 * With ZNS drives, closing an explicitly open zone that has not been
+	 * written will change the zone state to "closed", that is, the zone
+	 * will remain active. Since this can then cause failure of explicit
+	 * open operation on other zones if the drive active zone resources
+	 * are exceeded, make sure that the zone does not remain active by
+	 * resetting it.
+	 */
+	if (op == REQ_OP_ZONE_CLOSE && !z->z_wpoffset)
+		op = REQ_OP_ZONE_RESET;
+
+	trace_zonefs_zone_mgmt(sb, z, op);
+	ret = blkdev_zone_mgmt(sb->s_bdev, op, z->z_sector,
+			       z->z_size >> SECTOR_SHIFT);
+	if (ret) {
+		zonefs_err(sb,
+			   "Zone management operation %s at %llu failed %d\n",
+			   blk_op_str(op), z->z_sector, ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+int zonefs_inode_zone_mgmt(struct inode *inode, enum req_op op)
+{
+	lockdep_assert_held(&ZONEFS_I(inode)->i_truncate_mutex);
+
+	return zonefs_zone_mgmt(inode->i_sb, zonefs_inode_zone(inode), op);
+}
+
+void zonefs_i_size_write(struct inode *inode, loff_t isize)
+{
+	struct zonefs_zone *z = zonefs_inode_zone(inode);
+
+	i_size_write(inode, isize);
+
+	/*
+	 * A full zone is no longer open/active and does not need
+	 * explicit closing.
+	 */
+	if (isize >= z->z_capacity) {
+		struct zonefs_sb_info *sbi = ZONEFS_SB(inode->i_sb);
+
+		if (z->z_flags & ZONEFS_ZONE_ACTIVE)
+			atomic_dec(&sbi->s_active_seq_files);
+		z->z_flags &= ~(ZONEFS_ZONE_OPEN | ZONEFS_ZONE_ACTIVE);
+	}
+}
+
+void zonefs_update_stats(struct inode *inode, loff_t new_isize)
+{
+	struct super_block *sb = inode->i_sb;
+	struct zonefs_sb_info *sbi = ZONEFS_SB(sb);
+	loff_t old_isize = i_size_read(inode);
+	loff_t nr_blocks;
+
+	if (new_isize == old_isize)
+		return;
+
+	spin_lock(&sbi->s_lock);
+
+	/*
+	 * This may be called for an update after an IO error.
+	 * So beware of the values seen.
+	 */
+	if (new_isize < old_isize) {
+		nr_blocks = (old_isize - new_isize) >> sb->s_blocksize_bits;
+		if (sbi->s_used_blocks > nr_blocks)
+			sbi->s_used_blocks -= nr_blocks;
+		else
+			sbi->s_used_blocks = 0;
+	} else {
+		sbi->s_used_blocks +=
+			(new_isize - old_isize) >> sb->s_blocksize_bits;
+		if (sbi->s_used_blocks > sbi->s_blocks)
+			sbi->s_used_blocks = sbi->s_blocks;
+	}
+
+	spin_unlock(&sbi->s_lock);
+}
+
+/*
+ * Check a zone condition. Return the amount of written (and still readable)
+ * data in the zone.
+ */
+static loff_t zonefs_check_zone_condition(struct super_block *sb,
+					  struct zonefs_zone *z,
+					  struct blk_zone *zone)
+{
+	switch (zone->cond) {
+	case BLK_ZONE_COND_OFFLINE:
+		zonefs_warn(sb, "Zone %llu: offline zone\n",
+			    z->z_sector);
+		z->z_flags |= ZONEFS_ZONE_OFFLINE;
+		return 0;
+	case BLK_ZONE_COND_READONLY:
+		/*
+		 * The write pointer of read-only zones is invalid, so we cannot
+		 * determine the zone wpoffset (inode size). We thus keep the
+		 * zone wpoffset as is, which leads to an empty file
+		 * (wpoffset == 0) on mount. For a runtime error, this keeps
+		 * the inode size as it was when last updated so that the user
+		 * can recover data.
+		 */
+		zonefs_warn(sb, "Zone %llu: read-only zone\n",
+			    z->z_sector);
+		z->z_flags |= ZONEFS_ZONE_READONLY;
+		if (zonefs_zone_is_cnv(z))
+			return z->z_capacity;
+		return z->z_wpoffset;
+	case BLK_ZONE_COND_FULL:
+		/* The write pointer of full zones is invalid. */
+		return z->z_capacity;
+	default:
+		if (zonefs_zone_is_cnv(z))
+			return z->z_capacity;
+		return (zone->wp - zone->start) << SECTOR_SHIFT;
+	}
+}
+
+/*
+ * Check a zone condition and adjust its inode access permissions for
+ * offline and readonly zones.
+ */
+static void zonefs_inode_update_mode(struct inode *inode)
+{
+	struct zonefs_zone *z = zonefs_inode_zone(inode);
+
+	if (z->z_flags & ZONEFS_ZONE_OFFLINE) {
+		/* Offline zones cannot be read nor written */
+		inode->i_flags |= S_IMMUTABLE;
+		inode->i_mode &= ~0777;
+	} else if (z->z_flags & ZONEFS_ZONE_READONLY) {
+		/* Readonly zones cannot be written */
+		inode->i_flags |= S_IMMUTABLE;
+		if (z->z_flags & ZONEFS_ZONE_INIT_MODE)
+			inode->i_mode &= ~0777;
+		else
+			inode->i_mode &= ~0222;
+	}
+
+	z->z_flags &= ~ZONEFS_ZONE_INIT_MODE;
+	z->z_mode = inode->i_mode;
+}
+
+static int zonefs_io_error_cb(struct blk_zone *zone, unsigned int idx,
+			      void *data)
+{
+	struct blk_zone *z = data;
+
+	*z = *zone;
+	return 0;
+}
+
+static void zonefs_handle_io_error(struct inode *inode, struct blk_zone *zone,
+				   bool write)
+{
+	struct zonefs_zone *z = zonefs_inode_zone(inode);
+	struct super_block *sb = inode->i_sb;
+	struct zonefs_sb_info *sbi = ZONEFS_SB(sb);
+	loff_t isize, data_size;
+
+	/*
+	 * Check the zone condition: if the zone is not "bad" (offline or
+	 * read-only), read errors are simply signaled to the IO issuer as long
+	 * as there is no inconsistency between the inode size and the amount of
+	 * data written in the zone (data_size).
+	 */
+	data_size = zonefs_check_zone_condition(sb, z, zone);
+	isize = i_size_read(inode);
+	if (!(z->z_flags & (ZONEFS_ZONE_READONLY | ZONEFS_ZONE_OFFLINE)) &&
+	    !write && isize == data_size)
+		return;
+
+	/*
+	 * At this point, we detected either a bad zone or an inconsistency
+	 * between the inode size and the amount of data written in the zone.
+	 * For the latter case, the cause may be a write IO error or an external
+	 * action on the device. Two error patterns exist:
+	 * 1) The inode size is lower than the amount of data in the zone:
+	 *    a write operation partially failed and data was written at the end
+	 *    of the file. This can happen in the case of a large direct IO
+	 *    needing several BIOs and/or write requests to be processed.
+	 * 2) The inode size is larger than the amount of data in the zone:
+	 *    this can happen with a deferred write error with the use of the
+	 *    device side write cache after getting successful write IO
+	 *    completions. Other possibilities are (a) an external corruption,
+	 *    e.g. an application reset the zone directly, or (b) the device
+	 *    has a serious problem (e.g. firmware bug).
+	 *
+	 * In all cases, warn about inode size inconsistency and handle the
+	 * IO error according to the zone condition and to the mount options.
+	 */
+	if (isize != data_size)
+		zonefs_warn(sb,
+			    "inode %llu: invalid size %lld (should be %lld)\n",
+			    inode->i_ino, isize, data_size);
+
+	/*
+	 * First handle bad zones signaled by hardware. The mount options
+	 * errors=zone-ro and errors=zone-offline result in changing the
+	 * zone condition to read-only and offline respectively, as if the
+	 * condition was signaled by the hardware.
+	 */
+	if ((z->z_flags & ZONEFS_ZONE_OFFLINE) ||
+	    (sbi->s_mount_opts & ZONEFS_MNTOPT_ERRORS_ZOL)) {
+		zonefs_warn(sb, "inode %llu: read/write access disabled\n",
+			    inode->i_ino);
+		if (!(z->z_flags & ZONEFS_ZONE_OFFLINE))
+			z->z_flags |= ZONEFS_ZONE_OFFLINE;
+		zonefs_inode_update_mode(inode);
+		data_size = 0;
+	} else if ((z->z_flags & ZONEFS_ZONE_READONLY) ||
+		   (sbi->s_mount_opts & ZONEFS_MNTOPT_ERRORS_ZRO)) {
+		zonefs_warn(sb, "inode %llu: write access disabled\n",
+			    inode->i_ino);
+		if (!(z->z_flags & ZONEFS_ZONE_READONLY))
+			z->z_flags |= ZONEFS_ZONE_READONLY;
+		zonefs_inode_update_mode(inode);
+		data_size = isize;
+	} else if (sbi->s_mount_opts & ZONEFS_MNTOPT_ERRORS_RO &&
+		   data_size > isize) {
+		/* Do not expose garbage data */
+		data_size = isize;
+	}
+
+	/*
+	 * If the filesystem is mounted with the explicit-open mount option, we
+	 * need to clear the ZONEFS_ZONE_OPEN flag if the zone transitioned to
+	 * the read-only or offline condition, to avoid attempting an explicit
+	 * close of the zone when the inode file is closed.
+	 */
+	if ((sbi->s_mount_opts & ZONEFS_MNTOPT_EXPLICIT_OPEN) &&
+	    (z->z_flags & (ZONEFS_ZONE_READONLY | ZONEFS_ZONE_OFFLINE)))
+		z->z_flags &= ~ZONEFS_ZONE_OPEN;
+
+	/*
+	 * If error=remount-ro was specified, any error result in remounting
+	 * the volume as read-only.
+	 */
+	if ((sbi->s_mount_opts & ZONEFS_MNTOPT_ERRORS_RO) && !sb_rdonly(sb)) {
+		zonefs_warn(sb, "remounting filesystem read-only\n");
+		sb->s_flags |= SB_RDONLY;
+	}
+
+	/*
+	 * Update block usage stats and the inode size  to prevent access to
+	 * invalid data.
+	 */
+	zonefs_update_stats(inode, data_size);
+	zonefs_i_size_write(inode, data_size);
+	z->z_wpoffset = data_size;
+	zonefs_inode_account_active(inode);
+}
+
+/*
+ * When an file IO error occurs, check the file zone to see if there is a change
+ * in the zone condition (e.g. offline or read-only). For a failed write to a
+ * sequential zone, the zone write pointer position must also be checked to
+ * eventually correct the file size and zonefs inode write pointer offset
+ * (which can be out of sync with the drive due to partial write failures).
+ */
+void __zonefs_io_error(struct inode *inode, bool write)
+{
+	struct zonefs_zone *z = zonefs_inode_zone(inode);
+	struct super_block *sb = inode->i_sb;
+	unsigned int noio_flag;
+	struct blk_zone zone;
+	int ret;
+
+	/*
+	 * Conventional zone have no write pointer and cannot become read-only
+	 * or offline. So simply fake a report for a single or aggregated zone
+	 * and let zonefs_handle_io_error() correct the zone inode information
+	 * according to the mount options.
+	 */
+	if (!zonefs_zone_is_seq(z)) {
+		zone.start = z->z_sector;
+		zone.len = z->z_size >> SECTOR_SHIFT;
+		zone.wp = zone.start + zone.len;
+		zone.type = BLK_ZONE_TYPE_CONVENTIONAL;
+		zone.cond = BLK_ZONE_COND_NOT_WP;
+		zone.capacity = zone.len;
+		goto handle_io_error;
+	}
+
+	/*
+	 * Memory allocations in blkdev_report_zones() can trigger a memory
+	 * reclaim which may in turn cause a recursion into zonefs as well as
+	 * struct request allocations for the same device. The former case may
+	 * end up in a deadlock on the inode truncate mutex, while the latter
+	 * may prevent IO forward progress. Executing the report zones under
+	 * the GFP_NOIO context avoids both problems.
+	 */
+	noio_flag = memalloc_noio_save();
+	ret = blkdev_report_zones(sb->s_bdev, z->z_sector, 1,
+				  zonefs_io_error_cb, &zone);
+	memalloc_noio_restore(noio_flag);
+
+	if (ret != 1) {
+		zonefs_err(sb, "Get inode %llu zone information failed %d\n",
+			   inode->i_ino, ret);
+		zonefs_warn(sb, "remounting filesystem read-only\n");
+		sb->s_flags |= SB_RDONLY;
+		return;
+	}
+
+handle_io_error:
+	zonefs_handle_io_error(inode, &zone, write);
+}
+
+static struct kmem_cache *zonefs_inode_cachep;
+
+static struct inode *zonefs_alloc_inode(struct super_block *sb)
+{
+	struct zonefs_inode_info *zi;
+
+	zi = alloc_inode_sb(sb, zonefs_inode_cachep, GFP_KERNEL);
+	if (!zi)
+		return NULL;
+
+	inode_init_once(&zi->i_vnode);
+	mutex_init(&zi->i_truncate_mutex);
+	zi->i_wr_refcnt = 0;
+
+	return &zi->i_vnode;
+}
+
+static void zonefs_free_inode(struct inode *inode)
+{
+	kmem_cache_free(zonefs_inode_cachep, ZONEFS_I(inode));
+}
+
+/*
+ * File system stat.
+ */
+static int zonefs_statfs(struct dentry *dentry, struct kstatfs *buf)
+{
+	struct super_block *sb = dentry->d_sb;
+	struct zonefs_sb_info *sbi = ZONEFS_SB(sb);
+	enum zonefs_ztype t;
+
+	buf->f_type = ZONEFS_MAGIC;
+	buf->f_bsize = sb->s_blocksize;
+	buf->f_namelen = ZONEFS_NAME_MAX;
+
+	spin_lock(&sbi->s_lock);
+
+	buf->f_blocks = sbi->s_blocks;
+	if (WARN_ON(sbi->s_used_blocks > sbi->s_blocks))
+		buf->f_bfree = 0;
+	else
+		buf->f_bfree = buf->f_blocks - sbi->s_used_blocks;
+	buf->f_bavail = buf->f_bfree;
+
+	for (t = 0; t < ZONEFS_ZTYPE_MAX; t++) {
+		if (sbi->s_zgroup[t].g_nr_zones)
+			buf->f_files += sbi->s_zgroup[t].g_nr_zones + 1;
+	}
+	buf->f_ffree = 0;
+
+	spin_unlock(&sbi->s_lock);
+
+	buf->f_fsid = uuid_to_fsid(sbi->s_uuid.b);
+
+	return 0;
+}
+
+enum {
+	Opt_errors, Opt_explicit_open,
+};
+
+struct zonefs_context {
+	unsigned long s_mount_opts;
+};
+
+static const struct constant_table zonefs_param_errors[] = {
+	{"remount-ro",		ZONEFS_MNTOPT_ERRORS_RO},
+	{"zone-ro",		ZONEFS_MNTOPT_ERRORS_ZRO},
+	{"zone-offline",	ZONEFS_MNTOPT_ERRORS_ZOL},
+	{"repair", 		ZONEFS_MNTOPT_ERRORS_REPAIR},
+	{}
+};
+
+static const struct fs_parameter_spec zonefs_param_spec[] = {
+	fsparam_enum	("errors",		Opt_errors, zonefs_param_errors),
+	fsparam_flag	("explicit-open",	Opt_explicit_open),
+	{}
+};
+
+static int zonefs_parse_param(struct fs_context *fc, struct fs_parameter *param)
+{
+	struct zonefs_context *ctx = fc->fs_private;
+	struct fs_parse_result result;
+	int opt;
+
+	opt = fs_parse(fc, zonefs_param_spec, param, &result);
+	if (opt < 0)
+		return opt;
+
+	switch (opt) {
+	case Opt_errors:
+		ctx->s_mount_opts &= ~ZONEFS_MNTOPT_ERRORS_MASK;
+		ctx->s_mount_opts |= result.uint_32;
+		break;
+	case Opt_explicit_open:
+		ctx->s_mount_opts |= ZONEFS_MNTOPT_EXPLICIT_OPEN;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int zonefs_show_options(struct seq_file *seq, struct dentry *root)
+{
+	struct zonefs_sb_info *sbi = ZONEFS_SB(root->d_sb);
+
+	if (sbi->s_mount_opts & ZONEFS_MNTOPT_ERRORS_RO)
+		seq_puts(seq, ",errors=remount-ro");
+	if (sbi->s_mount_opts & ZONEFS_MNTOPT_ERRORS_ZRO)
+		seq_puts(seq, ",errors=zone-ro");
+	if (sbi->s_mount_opts & ZONEFS_MNTOPT_ERRORS_ZOL)
+		seq_puts(seq, ",errors=zone-offline");
+	if (sbi->s_mount_opts & ZONEFS_MNTOPT_ERRORS_REPAIR)
+		seq_puts(seq, ",errors=repair");
+
+	return 0;
+}
+
+static int zonefs_inode_setattr(struct mnt_idmap *idmap,
+				struct dentry *dentry, struct iattr *iattr)
+{
+	struct inode *inode = d_inode(dentry);
+	int ret;
+
+	if (unlikely(IS_IMMUTABLE(inode)))
+		return -EPERM;
+
+	ret = setattr_prepare(&nop_mnt_idmap, dentry, iattr);
+	if (ret)
+		return ret;
+
+	/*
+	 * Since files and directories cannot be created nor deleted, do not
+	 * allow setting any write attributes on the sub-directories grouping
+	 * files by zone type.
+	 */
+	if ((iattr->ia_valid & ATTR_MODE) && S_ISDIR(inode->i_mode) &&
+	    (iattr->ia_mode & 0222))
+		return -EPERM;
+
+	if (((iattr->ia_valid & ATTR_UID) &&
+	     !uid_eq(iattr->ia_uid, inode->i_uid)) ||
+	    ((iattr->ia_valid & ATTR_GID) &&
+	     !gid_eq(iattr->ia_gid, inode->i_gid))) {
+		ret = dquot_transfer(&nop_mnt_idmap, inode, iattr);
+		if (ret)
+			return ret;
+	}
+
+	if (iattr->ia_valid & ATTR_SIZE) {
+		ret = zonefs_file_truncate(inode, iattr->ia_size);
+		if (ret)
+			return ret;
+	}
+
+	setattr_copy(&nop_mnt_idmap, inode, iattr);
+
+	if (S_ISREG(inode->i_mode)) {
+		struct zonefs_zone *z = zonefs_inode_zone(inode);
+
+		z->z_mode = inode->i_mode;
+		z->z_uid = inode->i_uid;
+		z->z_gid = inode->i_gid;
+	}
+
+	return 0;
+}
+
+static const struct inode_operations zonefs_file_inode_operations = {
+	.setattr	= zonefs_inode_setattr,
+};
+
+static long zonefs_fname_to_fno(const struct qstr *fname)
+{
+	const char *name = fname->name;
+	unsigned int len = fname->len;
+	long fno = 0, shift = 1;
+	const char *rname;
+	char c = *name;
+	unsigned int i;
+
+	/*
+	 * File names are always a base-10 number string without any
+	 * leading 0s.
+	 */
+	if (!isdigit(c))
+		return -ENOENT;
+
+	if (len > 1 && c == '0')
+		return -ENOENT;
+
+	if (len == 1)
+		return c - '0';
+
+	for (i = 0, rname = name + len - 1; i < len; i++, rname--) {
+		long digit;
+
+		c = *rname;
+		if (!isdigit(c))
+			return -ENOENT;
+		digit = (c - '0') * shift;
+		if (check_add_overflow(fno, digit, &fno))
+			return -ENOENT;
+		shift *= 10;
+	}
+
+	return fno;
+}
+
+static struct inode *zonefs_get_file_inode(struct inode *dir,
+					   struct dentry *dentry)
+{
+	struct zonefs_zone_group *zgroup = dir->i_private;
+	struct super_block *sb = dir->i_sb;
+	struct zonefs_sb_info *sbi = ZONEFS_SB(sb);
+	struct zonefs_zone *z;
+	struct inode *inode;
+	ino_t ino;
+	long fno;
+
+	/* Get the file number from the file name */
+	fno = zonefs_fname_to_fno(&dentry->d_name);
+	if (fno < 0)
+		return ERR_PTR(fno);
+
+	if (!zgroup->g_nr_zones || fno >= zgroup->g_nr_zones)
+		return ERR_PTR(-ENOENT);
+
+	z = &zgroup->g_zones[fno];
+	ino = z->z_sector >> sbi->s_zone_sectors_shift;
+	inode = iget_locked(sb, ino);
+	if (!inode)
+		return ERR_PTR(-ENOMEM);
+	if (!(inode_state_read_once(inode) & I_NEW)) {
+		WARN_ON_ONCE(inode->i_private != z);
+		return inode;
+	}
+
+	inode->i_ino = ino;
+	inode->i_mode = z->z_mode;
+	inode_set_mtime_to_ts(inode,
+			      inode_set_atime_to_ts(inode, inode_set_ctime_to_ts(inode, inode_get_ctime(dir))));
+	inode->i_uid = z->z_uid;
+	inode->i_gid = z->z_gid;
+	inode->i_size = z->z_wpoffset;
+	inode->i_blocks = z->z_capacity >> SECTOR_SHIFT;
+	inode->i_private = z;
+
+	inode->i_op = &zonefs_file_inode_operations;
+	inode->i_fop = &zonefs_file_operations;
+	inode->i_mapping->a_ops = &zonefs_file_aops;
+	mapping_set_large_folios(inode->i_mapping);
+
+	/* Update the inode access rights depending on the zone condition */
+	zonefs_inode_update_mode(inode);
+
+	unlock_new_inode(inode);
+
+	return inode;
+}
+
+static struct inode *zonefs_get_zgroup_inode(struct super_block *sb,
+					     enum zonefs_ztype ztype)
+{
+	struct inode *root = d_inode(sb->s_root);
+	struct zonefs_sb_info *sbi = ZONEFS_SB(sb);
+	struct inode *inode;
+	ino_t ino = bdev_nr_zones(sb->s_bdev) + ztype + 1;
+
+	inode = iget_locked(sb, ino);
+	if (!inode)
+		return ERR_PTR(-ENOMEM);
+	if (!(inode_state_read_once(inode) & I_NEW))
+		return inode;
+
+	inode->i_ino = ino;
+	inode_init_owner(&nop_mnt_idmap, inode, root, S_IFDIR | 0555);
+	inode->i_size = sbi->s_zgroup[ztype].g_nr_zones;
+	inode_set_mtime_to_ts(inode,
+			      inode_set_atime_to_ts(inode, inode_set_ctime_to_ts(inode, inode_get_ctime(root))));
+	inode->i_private = &sbi->s_zgroup[ztype];
+	set_nlink(inode, 2);
+
+	inode->i_op = &zonefs_dir_inode_operations;
+	inode->i_fop = &zonefs_dir_operations;
+
+	unlock_new_inode(inode);
+
+	return inode;
+}
+
+
+static struct inode *zonefs_get_dir_inode(struct inode *dir,
+					  struct dentry *dentry)
+{
+	struct super_block *sb = dir->i_sb;
+	struct zonefs_sb_info *sbi = ZONEFS_SB(sb);
+	const char *name = dentry->d_name.name;
+	enum zonefs_ztype ztype;
+
+	/*
+	 * We only need to check for the "seq" directory and
+	 * the "cnv" directory if we have conventional zones.
+	 */
+	if (dentry->d_name.len != 3)
+		return ERR_PTR(-ENOENT);
+
+	for (ztype = 0; ztype < ZONEFS_ZTYPE_MAX; ztype++) {
+		if (sbi->s_zgroup[ztype].g_nr_zones &&
+		    memcmp(name, zonefs_zgroup_name(ztype), 3) == 0)
+			break;
+	}
+	if (ztype == ZONEFS_ZTYPE_MAX)
+		return ERR_PTR(-ENOENT);
+
+	return zonefs_get_zgroup_inode(sb, ztype);
+}
+
+static struct dentry *zonefs_lookup(struct inode *dir, struct dentry *dentry,
+				    unsigned int flags)
+{
+	struct inode *inode;
+
+	if (dentry->d_name.len > ZONEFS_NAME_MAX)
+		return ERR_PTR(-ENAMETOOLONG);
+
+	if (dir == d_inode(dir->i_sb->s_root))
+		inode = zonefs_get_dir_inode(dir, dentry);
+	else
+		inode = zonefs_get_file_inode(dir, dentry);
+
+	return d_splice_alias(inode, dentry);
+}
+
+static int zonefs_readdir_root(struct file *file, struct dir_context *ctx)
+{
+	struct inode *inode = file_inode(file);
+	struct super_block *sb = inode->i_sb;
+	struct zonefs_sb_info *sbi = ZONEFS_SB(sb);
+	enum zonefs_ztype ztype = ZONEFS_ZTYPE_CNV;
+	ino_t base_ino = bdev_nr_zones(sb->s_bdev) + 1;
+
+	if (ctx->pos >= inode->i_size)
+		return 0;
+
+	if (!dir_emit_dots(file, ctx))
+		return 0;
+
+	if (ctx->pos == 2) {
+		if (!sbi->s_zgroup[ZONEFS_ZTYPE_CNV].g_nr_zones)
+			ztype = ZONEFS_ZTYPE_SEQ;
+
+		if (!dir_emit(ctx, zonefs_zgroup_name(ztype), 3,
+			      base_ino + ztype, DT_DIR))
+			return 0;
+		ctx->pos++;
+	}
+
+	if (ctx->pos == 3 && ztype != ZONEFS_ZTYPE_SEQ) {
+		ztype = ZONEFS_ZTYPE_SEQ;
+		if (!dir_emit(ctx, zonefs_zgroup_name(ztype), 3,
+			      base_ino + ztype, DT_DIR))
+			return 0;
+		ctx->pos++;
+	}
+
+	return 0;
+}
+
+static int zonefs_readdir_zgroup(struct file *file,
+				 struct dir_context *ctx)
+{
+	struct inode *inode = file_inode(file);
+	struct zonefs_zone_group *zgroup = inode->i_private;
+	struct super_block *sb = inode->i_sb;
+	struct zonefs_sb_info *sbi = ZONEFS_SB(sb);
+	struct zonefs_zone *z;
+	int fname_len;
+	char *fname;
+	ino_t ino;
+	int f;
+
+	/*
+	 * The size of zone group directories is equal to the number
+	 * of zone files in the group and does note include the "." and
+	 * ".." entries. Hence the "+ 2" here.
+	 */
+	if (ctx->pos >= inode->i_size + 2)
+		return 0;
+
+	if (!dir_emit_dots(file, ctx))
+		return 0;
+
+	fname = kmalloc(ZONEFS_NAME_MAX, GFP_KERNEL);
+	if (!fname)
+		return -ENOMEM;
+
+	for (f = ctx->pos - 2; f < zgroup->g_nr_zones; f++) {
+		z = &zgroup->g_zones[f];
+		ino = z->z_sector >> sbi->s_zone_sectors_shift;
+		fname_len = snprintf(fname, ZONEFS_NAME_MAX - 1, "%u", f);
+		if (!dir_emit(ctx, fname, fname_len, ino, DT_REG))
+			break;
+		ctx->pos++;
+	}
+
+	kfree(fname);
+
+	return 0;
+}
+
+static int zonefs_readdir(struct file *file, struct dir_context *ctx)
+{
+	struct inode *inode = file_inode(file);
+
+	if (inode == d_inode(inode->i_sb->s_root))
+		return zonefs_readdir_root(file, ctx);
+
+	return zonefs_readdir_zgroup(file, ctx);
+}
+
+const struct inode_operations zonefs_dir_inode_operations = {
+	.lookup		= zonefs_lookup,
+	.setattr	= zonefs_inode_setattr,
+};
+
+const struct file_operations zonefs_dir_operations = {
+	.llseek		= generic_file_llseek,
+	.read		= generic_read_dir,
+	.iterate_shared	= zonefs_readdir,
+};
+
+struct zonefs_zone_data {
+	struct super_block	*sb;
+	unsigned int		nr_zones[ZONEFS_ZTYPE_MAX];
+	sector_t		cnv_zone_start;
+	struct blk_zone		*zones;
+};
+
+static int zonefs_get_zone_info_cb(struct blk_zone *zone, unsigned int idx,
+				   void *data)
+{
+	struct zonefs_zone_data *zd = data;
+	struct super_block *sb = zd->sb;
+	struct zonefs_sb_info *sbi = ZONEFS_SB(sb);
+
+	/*
+	 * We do not care about the first zone: it contains the super block
+	 * and not exposed as a file.
+	 */
+	if (!idx)
+		return 0;
+
+	/*
+	 * Count the number of zones that will be exposed as files.
+	 * For sequential zones, we always have as many files as zones.
+	 * FOr conventional zones, the number of files depends on if we have
+	 * conventional zones aggregation enabled.
+	 */
+	switch (zone->type) {
+	case BLK_ZONE_TYPE_CONVENTIONAL:
+		if (sbi->s_features & ZONEFS_F_AGGRCNV) {
+			/* One file per set of contiguous conventional zones */
+			if (!(sbi->s_zgroup[ZONEFS_ZTYPE_CNV].g_nr_zones) ||
+			    zone->start != zd->cnv_zone_start)
+				sbi->s_zgroup[ZONEFS_ZTYPE_CNV].g_nr_zones++;
+			zd->cnv_zone_start = zone->start + zone->len;
+		} else {
+			/* One file per zone */
+			sbi->s_zgroup[ZONEFS_ZTYPE_CNV].g_nr_zones++;
+		}
+		break;
+	case BLK_ZONE_TYPE_SEQWRITE_REQ:
+	case BLK_ZONE_TYPE_SEQWRITE_PREF:
+		sbi->s_zgroup[ZONEFS_ZTYPE_SEQ].g_nr_zones++;
+		break;
+	default:
+		zonefs_err(zd->sb, "Unsupported zone type 0x%x\n",
+			   zone->type);
+		return -EIO;
+	}
+
+	memcpy(&zd->zones[idx], zone, sizeof(struct blk_zone));
+
+	return 0;
+}
+
+static int zonefs_get_zone_info(struct zonefs_zone_data *zd)
+{
+	struct block_device *bdev = zd->sb->s_bdev;
+	int ret;
+
+	zd->zones = kvzalloc_objs(struct blk_zone, bdev_nr_zones(bdev));
+	if (!zd->zones)
+		return -ENOMEM;
+
+	/* Get zones information from the device */
+	ret = blkdev_report_zones(bdev, 0, BLK_ALL_ZONES,
+				  zonefs_get_zone_info_cb, zd);
+	if (ret < 0) {
+		zonefs_err(zd->sb, "Zone report failed %d\n", ret);
+		return ret;
+	}
+
+	if (ret != bdev_nr_zones(bdev)) {
+		zonefs_err(zd->sb, "Invalid zone report (%d/%u zones)\n",
+			   ret, bdev_nr_zones(bdev));
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static inline void zonefs_free_zone_info(struct zonefs_zone_data *zd)
+{
+	kvfree(zd->zones);
+}
+
+/*
+ * Create a zone group and populate it with zone files.
+ */
+static int zonefs_init_zgroup(struct super_block *sb,
+			      struct zonefs_zone_data *zd,
+			      enum zonefs_ztype ztype)
+{
+	struct zonefs_sb_info *sbi = ZONEFS_SB(sb);
+	struct zonefs_zone_group *zgroup = &sbi->s_zgroup[ztype];
+	struct blk_zone *zone, *next, *end;
+	struct zonefs_zone *z;
+	unsigned int n = 0;
+	int ret;
+
+	/* Allocate the zone group. If it is empty, we have nothing to do. */
+	if (!zgroup->g_nr_zones)
+		return 0;
+
+	zgroup->g_zones = kvzalloc_objs(struct zonefs_zone, zgroup->g_nr_zones);
+	if (!zgroup->g_zones)
+		return -ENOMEM;
+
+	/*
+	 * Initialize the zone groups using the device zone information.
+	 * We always skip the first zone as it contains the super block
+	 * and is not use to back a file.
+	 */
+	end = zd->zones + bdev_nr_zones(sb->s_bdev);
+	for (zone = &zd->zones[1]; zone < end; zone = next) {
+
+		next = zone + 1;
+		if (zonefs_zone_type(zone) != ztype)
+			continue;
+
+		if (WARN_ON_ONCE(n >= zgroup->g_nr_zones))
+			return -EINVAL;
+
+		/*
+		 * For conventional zones, contiguous zones can be aggregated
+		 * together to form larger files. Note that this overwrites the
+		 * length of the first zone of the set of contiguous zones
+		 * aggregated together. If one offline or read-only zone is
+		 * found, assume that all zones aggregated have the same
+		 * condition.
+		 */
+		if (ztype == ZONEFS_ZTYPE_CNV &&
+		    (sbi->s_features & ZONEFS_F_AGGRCNV)) {
+			for (; next < end; next++) {
+				if (zonefs_zone_type(next) != ztype)
+					break;
+				zone->len += next->len;
+				zone->capacity += next->capacity;
+				if (next->cond == BLK_ZONE_COND_READONLY &&
+				    zone->cond != BLK_ZONE_COND_OFFLINE)
+					zone->cond = BLK_ZONE_COND_READONLY;
+				else if (next->cond == BLK_ZONE_COND_OFFLINE)
+					zone->cond = BLK_ZONE_COND_OFFLINE;
+			}
+		}
+
+		z = &zgroup->g_zones[n];
+		if (ztype == ZONEFS_ZTYPE_CNV)
+			z->z_flags |= ZONEFS_ZONE_CNV;
+		z->z_sector = zone->start;
+		z->z_size = zone->len << SECTOR_SHIFT;
+		if (z->z_size > bdev_zone_sectors(sb->s_bdev) << SECTOR_SHIFT &&
+		    !(sbi->s_features & ZONEFS_F_AGGRCNV)) {
+			zonefs_err(sb,
+				"Invalid zone size %llu (device zone sectors %llu)\n",
+				z->z_size,
+				bdev_zone_sectors(sb->s_bdev) << SECTOR_SHIFT);
+			return -EINVAL;
+		}
+
+		z->z_capacity = min_t(loff_t, MAX_LFS_FILESIZE,
+				      zone->capacity << SECTOR_SHIFT);
+		z->z_wpoffset = zonefs_check_zone_condition(sb, z, zone);
+
+		z->z_mode = S_IFREG | sbi->s_perm;
+		z->z_uid = sbi->s_uid;
+		z->z_gid = sbi->s_gid;
+
+		/*
+		 * Let zonefs_inode_update_mode() know that we will need
+		 * special initialization of the inode mode the first time
+		 * it is accessed.
+		 */
+		z->z_flags |= ZONEFS_ZONE_INIT_MODE;
+
+		sb->s_maxbytes = max(z->z_capacity, sb->s_maxbytes);
+		sbi->s_blocks += z->z_capacity >> sb->s_blocksize_bits;
+		sbi->s_used_blocks += z->z_wpoffset >> sb->s_blocksize_bits;
+
+		/*
+		 * For sequential zones, make sure that any open zone is closed
+		 * first to ensure that the initial number of open zones is 0,
+		 * in sync with the open zone accounting done when the mount
+		 * option ZONEFS_MNTOPT_EXPLICIT_OPEN is used.
+		 */
+		if (ztype == ZONEFS_ZTYPE_SEQ &&
+		    (zone->cond == BLK_ZONE_COND_IMP_OPEN ||
+		     zone->cond == BLK_ZONE_COND_EXP_OPEN)) {
+			ret = zonefs_zone_mgmt(sb, z, REQ_OP_ZONE_CLOSE);
+			if (ret)
+				return ret;
+		}
+
+		zonefs_account_active(sb, z);
+
+		n++;
+	}
+
+	if (WARN_ON_ONCE(n != zgroup->g_nr_zones))
+		return -EINVAL;
+
+	zonefs_info(sb, "Zone group \"%s\" has %u file%s\n",
+		    zonefs_zgroup_name(ztype),
+		    zgroup->g_nr_zones,
+		    str_plural(zgroup->g_nr_zones));
+
+	return 0;
+}
+
+static void zonefs_free_zgroups(struct super_block *sb)
+{
+	struct zonefs_sb_info *sbi = ZONEFS_SB(sb);
+	enum zonefs_ztype ztype;
+
+	if (!sbi)
+		return;
+
+	for (ztype = 0; ztype < ZONEFS_ZTYPE_MAX; ztype++) {
+		kvfree(sbi->s_zgroup[ztype].g_zones);
+		sbi->s_zgroup[ztype].g_zones = NULL;
+	}
+}
+
+/*
+ * Create a zone group and populate it with zone files.
+ */
+static int zonefs_init_zgroups(struct super_block *sb)
+{
+	struct zonefs_zone_data zd;
+	enum zonefs_ztype ztype;
+	int ret;
+
+	/* First get the device zone information */
+	memset(&zd, 0, sizeof(struct zonefs_zone_data));
+	zd.sb = sb;
+	ret = zonefs_get_zone_info(&zd);
+	if (ret)
+		goto cleanup;
+
+	/* Allocate and initialize the zone groups */
+	for (ztype = 0; ztype < ZONEFS_ZTYPE_MAX; ztype++) {
+		ret = zonefs_init_zgroup(sb, &zd, ztype);
+		if (ret) {
+			zonefs_info(sb,
+				    "Zone group \"%s\" initialization failed\n",
+				    zonefs_zgroup_name(ztype));
+			break;
+		}
+	}
+
+cleanup:
+	zonefs_free_zone_info(&zd);
+	if (ret)
+		zonefs_free_zgroups(sb);
+
+	return ret;
+}
+
+/*
+ * Read super block information from the device.
+ */
+static int zonefs_read_super(struct super_block *sb)
+{
+	struct zonefs_sb_info *sbi = ZONEFS_SB(sb);
+	struct zonefs_super *super;
+	u32 crc, stored_crc;
+	int ret;
+
+	super = kmalloc(ZONEFS_SUPER_SIZE, GFP_KERNEL);
+	if (!super)
+		return -ENOMEM;
+
+	ret = bdev_rw_virt(sb->s_bdev, 0, super, ZONEFS_SUPER_SIZE,
+			   REQ_OP_READ);
+	if (ret)
+		goto free_super;
+
+	ret = -EINVAL;
+	if (le32_to_cpu(super->s_magic) != ZONEFS_MAGIC)
+		goto free_super;
+
+	stored_crc = le32_to_cpu(super->s_crc);
+	super->s_crc = 0;
+	crc = crc32(~0U, (unsigned char *)super, sizeof(struct zonefs_super));
+	if (crc != stored_crc) {
+		zonefs_err(sb, "Invalid checksum (Expected 0x%08x, got 0x%08x)",
+			   crc, stored_crc);
+		goto free_super;
+	}
+
+	sbi->s_features = le64_to_cpu(super->s_features);
+	if (sbi->s_features & ~ZONEFS_F_DEFINED_FEATURES) {
+		zonefs_err(sb, "Unknown features set 0x%llx\n",
+			   sbi->s_features);
+		goto free_super;
+	}
+
+	if (sbi->s_features & ZONEFS_F_UID) {
+		sbi->s_uid = make_kuid(current_user_ns(),
+				       le32_to_cpu(super->s_uid));
+		if (!uid_valid(sbi->s_uid)) {
+			zonefs_err(sb, "Invalid UID feature\n");
+			goto free_super;
+		}
+	}
+
+	if (sbi->s_features & ZONEFS_F_GID) {
+		sbi->s_gid = make_kgid(current_user_ns(),
+				       le32_to_cpu(super->s_gid));
+		if (!gid_valid(sbi->s_gid)) {
+			zonefs_err(sb, "Invalid GID feature\n");
+			goto free_super;
+		}
+	}
+
+	if (sbi->s_features & ZONEFS_F_PERM)
+		sbi->s_perm = le32_to_cpu(super->s_perm);
+
+	if (memchr_inv(super->s_reserved, 0, sizeof(super->s_reserved))) {
+		zonefs_err(sb, "Reserved area is being used\n");
+		goto free_super;
+	}
+
+	import_uuid(&sbi->s_uuid, super->s_uuid);
+	ret = 0;
+
+free_super:
+	kfree(super);
+	return ret;
+}
+
+static const struct super_operations zonefs_sops = {
+	.alloc_inode	= zonefs_alloc_inode,
+	.free_inode	= zonefs_free_inode,
+	.statfs		= zonefs_statfs,
+	.show_options	= zonefs_show_options,
+};
+
+static int zonefs_get_zgroup_inodes(struct super_block *sb)
+{
+	struct zonefs_sb_info *sbi = ZONEFS_SB(sb);
+	struct inode *dir_inode;
+	enum zonefs_ztype ztype;
+
+	for (ztype = 0; ztype < ZONEFS_ZTYPE_MAX; ztype++) {
+		if (!sbi->s_zgroup[ztype].g_nr_zones)
+			continue;
+
+		dir_inode = zonefs_get_zgroup_inode(sb, ztype);
+		if (IS_ERR(dir_inode))
+			return PTR_ERR(dir_inode);
+
+		sbi->s_zgroup[ztype].g_inode = dir_inode;
+	}
+
+	return 0;
+}
+
+static void zonefs_release_zgroup_inodes(struct super_block *sb)
+{
+	struct zonefs_sb_info *sbi = ZONEFS_SB(sb);
+	enum zonefs_ztype ztype;
+
+	if (!sbi)
+		return;
+
+	for (ztype = 0; ztype < ZONEFS_ZTYPE_MAX; ztype++) {
+		if (sbi->s_zgroup[ztype].g_inode) {
+			iput(sbi->s_zgroup[ztype].g_inode);
+			sbi->s_zgroup[ztype].g_inode = NULL;
+		}
+	}
+}
+
+/*
+ * Check that the device is zoned. If it is, get the list of zones and create
+ * sub-directories and files according to the device zone configuration and
+ * format options.
+ */
+static int zonefs_fill_super(struct super_block *sb, struct fs_context *fc)
+{
+	struct zonefs_sb_info *sbi;
+	struct zonefs_context *ctx = fc->fs_private;
+	struct inode *inode;
+	enum zonefs_ztype ztype;
+	int ret;
+
+	if (!bdev_is_zoned(sb->s_bdev)) {
+		zonefs_err(sb, "Not a zoned block device\n");
+		return -EINVAL;
+	}
+
+	/*
+	 * Initialize super block information: the maximum file size is updated
+	 * when the zone files are created so that the format option
+	 * ZONEFS_F_AGGRCNV which increases the maximum file size of a file
+	 * beyond the zone size is taken into account.
+	 */
+	sbi = kzalloc_obj(*sbi);
+	if (!sbi)
+		return -ENOMEM;
+
+	spin_lock_init(&sbi->s_lock);
+	sb->s_fs_info = sbi;
+	sb->s_magic = ZONEFS_MAGIC;
+	sb->s_maxbytes = 0;
+	sb->s_op = &zonefs_sops;
+	sb->s_time_gran	= 1;
+
+	/*
+	 * The block size is set to the device zone write granularity to ensure
+	 * that write operations are always aligned according to the device
+	 * interface constraints.
+	 */
+	sb_set_blocksize(sb, bdev_zone_write_granularity(sb->s_bdev));
+	sbi->s_zone_sectors_shift = ilog2(bdev_zone_sectors(sb->s_bdev));
+	sbi->s_uid = GLOBAL_ROOT_UID;
+	sbi->s_gid = GLOBAL_ROOT_GID;
+	sbi->s_perm = 0640;
+	sbi->s_mount_opts = ctx->s_mount_opts;
+
+	atomic_set(&sbi->s_wro_seq_files, 0);
+	sbi->s_max_wro_seq_files = bdev_max_open_zones(sb->s_bdev);
+	atomic_set(&sbi->s_active_seq_files, 0);
+	sbi->s_max_active_seq_files = bdev_max_active_zones(sb->s_bdev);
+
+	ret = zonefs_read_super(sb);
+	if (ret)
+		return ret;
+
+	zonefs_info(sb, "Mounting %u zones", bdev_nr_zones(sb->s_bdev));
+
+	if (!sbi->s_max_wro_seq_files &&
+	    !sbi->s_max_active_seq_files &&
+	    sbi->s_mount_opts & ZONEFS_MNTOPT_EXPLICIT_OPEN) {
+		zonefs_info(sb,
+			"No open and active zone limits. Ignoring explicit_open mount option\n");
+		sbi->s_mount_opts &= ~ZONEFS_MNTOPT_EXPLICIT_OPEN;
+	}
+
+	/* Initialize the zone groups */
+	ret = zonefs_init_zgroups(sb);
+	if (ret)
+		goto cleanup;
+
+	/* Create the root directory inode */
+	ret = -ENOMEM;
+	inode = new_inode(sb);
+	if (!inode)
+		goto cleanup;
+
+	inode->i_ino = bdev_nr_zones(sb->s_bdev);
+	inode->i_mode = S_IFDIR | 0555;
+	simple_inode_init_ts(inode);
+	inode->i_op = &zonefs_dir_inode_operations;
+	inode->i_fop = &zonefs_dir_operations;
+	inode->i_size = 2;
+	set_nlink(inode, 2);
+	for (ztype = 0; ztype < ZONEFS_ZTYPE_MAX; ztype++) {
+		if (sbi->s_zgroup[ztype].g_nr_zones) {
+			inc_nlink(inode);
+			inode->i_size++;
+		}
+	}
+
+	sb->s_root = d_make_root(inode);
+	if (!sb->s_root)
+		goto cleanup;
+
+	/*
+	 * Take a reference on the zone groups directory inodes
+	 * to keep them in the inode cache.
+	 */
+	ret = zonefs_get_zgroup_inodes(sb);
+	if (ret)
+		goto cleanup;
+
+	ret = zonefs_sysfs_register(sb);
+	if (ret)
+		goto cleanup;
+
+	return 0;
+
+cleanup:
+	zonefs_release_zgroup_inodes(sb);
+	zonefs_free_zgroups(sb);
+
+	return ret;
+}
+
+static void zonefs_kill_super(struct super_block *sb)
+{
+	struct zonefs_sb_info *sbi = ZONEFS_SB(sb);
+
+	/* Release the reference on the zone group directory inodes */
+	zonefs_release_zgroup_inodes(sb);
+
+	kill_block_super(sb);
+
+	zonefs_sysfs_unregister(sb);
+	zonefs_free_zgroups(sb);
+	kfree(sbi);
+}
+
+static void zonefs_free_fc(struct fs_context *fc)
+{
+	struct zonefs_context *ctx = fc->fs_private;
+
+	kfree(ctx);
+}
+
+static int zonefs_get_tree(struct fs_context *fc)
+{
+	return get_tree_bdev(fc, zonefs_fill_super);
+}
+
+static int zonefs_reconfigure(struct fs_context *fc)
+{
+	struct zonefs_context *ctx = fc->fs_private;
+	struct super_block *sb = fc->root->d_sb;
+	struct zonefs_sb_info *sbi = sb->s_fs_info;
+
+	sync_filesystem(fc->root->d_sb);
+	/* Copy new options from ctx into sbi. */
+	sbi->s_mount_opts = ctx->s_mount_opts;
+
+	return 0;
+}
+
+static const struct fs_context_operations zonefs_context_ops = {
+	.parse_param    = zonefs_parse_param,
+	.get_tree       = zonefs_get_tree,
+	.reconfigure	= zonefs_reconfigure,
+	.free           = zonefs_free_fc,
+};
+
+/*
+ * Set up the filesystem mount context.
+ */
+static int zonefs_init_fs_context(struct fs_context *fc)
+{
+	struct zonefs_context *ctx;
+
+	ctx = kzalloc_obj(struct zonefs_context);
+	if (!ctx)
+		return -ENOMEM;
+	ctx->s_mount_opts = ZONEFS_MNTOPT_ERRORS_RO;
+	fc->ops = &zonefs_context_ops;
+	fc->fs_private = ctx;
+
+	return 0;
+}
+
+/*
+ * File system definition and registration.
+ */
+static struct file_system_type zonefs_type = {
+	.owner			= THIS_MODULE,
+	.name			= "zonefs",
+	.kill_sb		= zonefs_kill_super,
+	.fs_flags		= FS_REQUIRES_DEV,
+	.init_fs_context	= zonefs_init_fs_context,
+	.parameters		= zonefs_param_spec,
+};
+
+static int __init zonefs_init_inodecache(void)
+{
+	zonefs_inode_cachep = kmem_cache_create("zonefs_inode_cache",
+			sizeof(struct zonefs_inode_info), 0,
+			SLAB_RECLAIM_ACCOUNT | SLAB_ACCOUNT,
+			NULL);
+	if (zonefs_inode_cachep == NULL)
+		return -ENOMEM;
+	return 0;
+}
+
+static void zonefs_destroy_inodecache(void)
+{
+	/*
+	 * Make sure all delayed rcu free inodes are flushed before we
+	 * destroy the inode cache.
+	 */
+	rcu_barrier();
+	kmem_cache_destroy(zonefs_inode_cachep);
+}
+
+static int __init zonefs_init(void)
+{
+	int ret;
+
+	BUILD_BUG_ON(sizeof(struct zonefs_super) != ZONEFS_SUPER_SIZE);
+
+	ret = zonefs_init_inodecache();
+	if (ret)
+		return ret;
+
+	ret = zonefs_sysfs_init();
+	if (ret)
+		goto destroy_inodecache;
+
+	ret = register_filesystem(&zonefs_type);
+	if (ret)
+		goto sysfs_exit;
+
+	return 0;
+
+sysfs_exit:
+	zonefs_sysfs_exit();
+destroy_inodecache:
+	zonefs_destroy_inodecache();
+
+	return ret;
+}
+
+static void __exit zonefs_exit(void)
+{
+	unregister_filesystem(&zonefs_type);
+	zonefs_sysfs_exit();
+	zonefs_destroy_inodecache();
+}
+
+MODULE_AUTHOR("Damien Le Moal");
+MODULE_DESCRIPTION("Zone file system for zoned block devices");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_FS("zonefs");
+module_init(zonefs_init);
+module_exit(zonefs_exit);
diff --git a/fs/zonefs/sysfs.c b/fs/zonefs/sysfs.c
new file mode 100644
index 000000000..ff9a688f1
--- /dev/null
+++ b/fs/zonefs/sysfs.c
@@ -0,0 +1,135 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Simple file system for zoned block devices exposing zones as files.
+ *
+ * Copyright (C) 2022 Western Digital Corporation or its affiliates.
+ */
+#include <linux/fs.h>
+#include <linux/seq_file.h>
+#include <linux/blkdev.h>
+
+#include "zonefs.h"
+
+struct zonefs_sysfs_attr {
+	struct attribute attr;
+	ssize_t (*show)(struct zonefs_sb_info *sbi, char *buf);
+};
+
+#define ZONEFS_SYSFS_ATTR_RO(name) \
+static struct zonefs_sysfs_attr zonefs_sysfs_attr_##name = __ATTR_RO(name)
+
+#define ATTR_LIST(name) &zonefs_sysfs_attr_##name.attr
+
+static ssize_t zonefs_sysfs_attr_show(struct kobject *kobj,
+				      struct attribute *attr, char *buf)
+{
+	struct zonefs_sb_info *sbi =
+		container_of(kobj, struct zonefs_sb_info, s_kobj);
+	struct zonefs_sysfs_attr *zonefs_attr =
+		container_of(attr, struct zonefs_sysfs_attr, attr);
+
+	if (!zonefs_attr->show)
+		return 0;
+
+	return zonefs_attr->show(sbi, buf);
+}
+
+static ssize_t max_wro_seq_files_show(struct zonefs_sb_info *sbi, char *buf)
+{
+	return sysfs_emit(buf, "%u\n", sbi->s_max_wro_seq_files);
+}
+ZONEFS_SYSFS_ATTR_RO(max_wro_seq_files);
+
+static ssize_t nr_wro_seq_files_show(struct zonefs_sb_info *sbi, char *buf)
+{
+	return sysfs_emit(buf, "%d\n", atomic_read(&sbi->s_wro_seq_files));
+}
+ZONEFS_SYSFS_ATTR_RO(nr_wro_seq_files);
+
+static ssize_t max_active_seq_files_show(struct zonefs_sb_info *sbi, char *buf)
+{
+	return sysfs_emit(buf, "%u\n", sbi->s_max_active_seq_files);
+}
+ZONEFS_SYSFS_ATTR_RO(max_active_seq_files);
+
+static ssize_t nr_active_seq_files_show(struct zonefs_sb_info *sbi, char *buf)
+{
+	return sysfs_emit(buf, "%d\n", atomic_read(&sbi->s_active_seq_files));
+}
+ZONEFS_SYSFS_ATTR_RO(nr_active_seq_files);
+
+static struct attribute *zonefs_sysfs_attrs[] = {
+	ATTR_LIST(max_wro_seq_files),
+	ATTR_LIST(nr_wro_seq_files),
+	ATTR_LIST(max_active_seq_files),
+	ATTR_LIST(nr_active_seq_files),
+	NULL,
+};
+ATTRIBUTE_GROUPS(zonefs_sysfs);
+
+static void zonefs_sysfs_sb_release(struct kobject *kobj)
+{
+	struct zonefs_sb_info *sbi =
+		container_of(kobj, struct zonefs_sb_info, s_kobj);
+
+	complete(&sbi->s_kobj_unregister);
+}
+
+static const struct sysfs_ops zonefs_sysfs_attr_ops = {
+	.show	= zonefs_sysfs_attr_show,
+};
+
+static const struct kobj_type zonefs_sb_ktype = {
+	.default_groups = zonefs_sysfs_groups,
+	.sysfs_ops	= &zonefs_sysfs_attr_ops,
+	.release	= zonefs_sysfs_sb_release,
+};
+
+static struct kobject *zonefs_sysfs_root;
+
+int zonefs_sysfs_register(struct super_block *sb)
+{
+	struct zonefs_sb_info *sbi = ZONEFS_SB(sb);
+	int ret;
+
+	super_set_sysfs_name_id(sb);
+	init_completion(&sbi->s_kobj_unregister);
+	ret = kobject_init_and_add(&sbi->s_kobj, &zonefs_sb_ktype,
+				   zonefs_sysfs_root, "%s", sb->s_id);
+	if (ret) {
+		kobject_put(&sbi->s_kobj);
+		wait_for_completion(&sbi->s_kobj_unregister);
+		return ret;
+	}
+
+	sbi->s_sysfs_registered = true;
+
+	return 0;
+}
+
+void zonefs_sysfs_unregister(struct super_block *sb)
+{
+	struct zonefs_sb_info *sbi = ZONEFS_SB(sb);
+
+	if (!sbi || !sbi->s_sysfs_registered)
+		return;
+
+	kobject_del(&sbi->s_kobj);
+	kobject_put(&sbi->s_kobj);
+	wait_for_completion(&sbi->s_kobj_unregister);
+}
+
+int __init zonefs_sysfs_init(void)
+{
+	zonefs_sysfs_root = kobject_create_and_add("zonefs", fs_kobj);
+	if (!zonefs_sysfs_root)
+		return -ENOMEM;
+
+	return 0;
+}
+
+void zonefs_sysfs_exit(void)
+{
+	kobject_put(zonefs_sysfs_root);
+	zonefs_sysfs_root = NULL;
+}
diff --git a/fs/zonefs/trace.h b/fs/zonefs/trace.h
new file mode 100644
index 000000000..7315a72ca
--- /dev/null
+++ b/fs/zonefs/trace.h
@@ -0,0 +1,106 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * zonefs filesystem driver tracepoints.
+ *
+ * Copyright (C) 2021 Western Digital Corporation or its affiliates.
+ */
+
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM zonefs
+
+#if !defined(_TRACE_ZONEFS_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_ZONEFS_H
+
+#include <linux/tracepoint.h>
+#include <linux/trace_seq.h>
+#include <linux/blkdev.h>
+
+#include "zonefs.h"
+
+#define show_dev(dev) MAJOR(dev), MINOR(dev)
+
+TRACE_EVENT(zonefs_zone_mgmt,
+	    TP_PROTO(struct super_block *sb, struct zonefs_zone *z,
+		     enum req_op op),
+	    TP_ARGS(sb, z, op),
+	    TP_STRUCT__entry(
+			     __field(dev_t, dev)
+			     __field(u64, ino)
+			     __field(enum req_op, op)
+			     __field(sector_t, sector)
+			     __field(sector_t, nr_sectors)
+	    ),
+	    TP_fast_assign(
+			   __entry->dev = sb->s_dev;
+			   __entry->ino =
+				z->z_sector >> ZONEFS_SB(sb)->s_zone_sectors_shift;
+			   __entry->op = op;
+			   __entry->sector = z->z_sector;
+			   __entry->nr_sectors = z->z_size >> SECTOR_SHIFT;
+	    ),
+	    TP_printk("bdev=(%d,%d), ino=%llu op=%s, sector=%llu, nr_sectors=%llu",
+		      show_dev(__entry->dev), __entry->ino,
+		      blk_op_str(__entry->op), __entry->sector,
+		      __entry->nr_sectors
+	    )
+);
+
+TRACE_EVENT(zonefs_file_dio_append,
+	    TP_PROTO(struct inode *inode, ssize_t size, ssize_t ret),
+	    TP_ARGS(inode, size, ret),
+	    TP_STRUCT__entry(
+			     __field(dev_t, dev)
+			     __field(u64, ino)
+			     __field(sector_t, sector)
+			     __field(ssize_t, size)
+			     __field(loff_t, wpoffset)
+			     __field(ssize_t, ret)
+	    ),
+	    TP_fast_assign(
+			   __entry->dev = inode->i_sb->s_dev;
+			   __entry->ino = inode->i_ino;
+			   __entry->sector = zonefs_inode_zone(inode)->z_sector;
+			   __entry->size = size;
+			   __entry->wpoffset =
+				zonefs_inode_zone(inode)->z_wpoffset;
+			   __entry->ret = ret;
+	    ),
+	    TP_printk("bdev=(%d, %d), ino=%llu, sector=%llu, size=%zu, wpoffset=%llu, ret=%zu",
+		      show_dev(__entry->dev), __entry->ino,
+		      __entry->sector, __entry->size, __entry->wpoffset,
+		      __entry->ret
+	    )
+);
+
+TRACE_EVENT(zonefs_iomap_begin,
+	    TP_PROTO(struct inode *inode, struct iomap *iomap),
+	    TP_ARGS(inode, iomap),
+	    TP_STRUCT__entry(
+			     __field(dev_t, dev)
+			     __field(u64, ino)
+			     __field(u64, addr)
+			     __field(loff_t, offset)
+			     __field(u64, length)
+	    ),
+	    TP_fast_assign(
+			   __entry->dev = inode->i_sb->s_dev;
+			   __entry->ino = inode->i_ino;
+			   __entry->addr = iomap->addr;
+			   __entry->offset = iomap->offset;
+			   __entry->length = iomap->length;
+	    ),
+	    TP_printk("bdev=(%d,%d), ino=%llu, addr=%llu, offset=%llu, length=%llu",
+		      show_dev(__entry->dev), __entry->ino,
+		      __entry->addr, __entry->offset, __entry->length
+	    )
+);
+
+#endif /* _TRACE_ZONEFS_H */
+
+#undef TRACE_INCLUDE_PATH
+#define TRACE_INCLUDE_PATH .
+#undef TRACE_INCLUDE_FILE
+#define TRACE_INCLUDE_FILE trace
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
diff --git a/fs/zonefs/zonefs.h b/fs/zonefs/zonefs.h
new file mode 100644
index 000000000..817565224
--- /dev/null
+++ b/fs/zonefs/zonefs.h
@@ -0,0 +1,289 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Simple zone file system for zoned block devices.
+ *
+ * Copyright (C) 2019 Western Digital Corporation or its affiliates.
+ */
+#ifndef __ZONEFS_H__
+#define __ZONEFS_H__
+
+#include <linux/fs.h>
+#include <linux/magic.h>
+#include <linux/uuid.h>
+#include <linux/mutex.h>
+#include <linux/rwsem.h>
+#include <linux/kobject.h>
+
+/*
+ * Maximum length of file names: this only needs to be large enough to fit
+ * the zone group directory names and a decimal zone number for file names.
+ * 16 characters is plenty.
+ */
+#define ZONEFS_NAME_MAX		16
+
+/*
+ * Zone types: ZONEFS_ZTYPE_SEQ is used for all sequential zone types
+ * defined in linux/blkzoned.h, that is, BLK_ZONE_TYPE_SEQWRITE_REQ and
+ * BLK_ZONE_TYPE_SEQWRITE_PREF.
+ */
+enum zonefs_ztype {
+	ZONEFS_ZTYPE_CNV,
+	ZONEFS_ZTYPE_SEQ,
+	ZONEFS_ZTYPE_MAX,
+};
+
+static inline enum zonefs_ztype zonefs_zone_type(struct blk_zone *zone)
+{
+	if (zone->type == BLK_ZONE_TYPE_CONVENTIONAL)
+		return ZONEFS_ZTYPE_CNV;
+	return ZONEFS_ZTYPE_SEQ;
+}
+
+#define ZONEFS_ZONE_INIT_MODE	(1U << 0)
+#define ZONEFS_ZONE_OPEN	(1U << 1)
+#define ZONEFS_ZONE_ACTIVE	(1U << 2)
+#define ZONEFS_ZONE_OFFLINE	(1U << 3)
+#define ZONEFS_ZONE_READONLY	(1U << 4)
+#define ZONEFS_ZONE_CNV		(1U << 31)
+
+/*
+ * In-memory per-file inode zone data.
+ */
+struct zonefs_zone {
+	/* Zone state flags */
+	unsigned int		z_flags;
+
+	/* Zone start sector (512B unit) */
+	sector_t		z_sector;
+
+	/* Zone size (bytes) */
+	loff_t			z_size;
+
+	/* Zone capacity (file maximum size, bytes) */
+	loff_t			z_capacity;
+
+	/* Write pointer offset in the zone (sequential zones only, bytes) */
+	loff_t			z_wpoffset;
+
+	/* Saved inode uid, gid and access rights */
+	umode_t			z_mode;
+	kuid_t			z_uid;
+	kgid_t			z_gid;
+};
+
+/*
+ * In memory zone group information: all zones of a group are exposed
+ * as files, one file per zone.
+ */
+struct zonefs_zone_group {
+	struct inode		*g_inode;
+	unsigned int		g_nr_zones;
+	struct zonefs_zone	*g_zones;
+};
+
+/*
+ * In-memory inode data.
+ */
+struct zonefs_inode_info {
+	struct inode		i_vnode;
+
+	/*
+	 * To serialise fully against both syscall and mmap based IO and
+	 * sequential file truncation, two locks are used. For serializing
+	 * zonefs_seq_file_truncate() against zonefs_iomap_begin(), that is,
+	 * file truncate operations against block mapping, i_truncate_mutex is
+	 * used. i_truncate_mutex also protects against concurrent accesses
+	 * and changes to the inode private data, and in particular changes to
+	 * a sequential file size on completion of direct IO writes.
+	 * Serialization of mmap read IOs with truncate and syscall IO
+	 * operations is done with invalidate_lock in addition to
+	 * i_truncate_mutex.  Only zonefs_seq_file_truncate() takes both lock
+	 * (invalidate_lock first, i_truncate_mutex second).
+	 */
+	struct mutex		i_truncate_mutex;
+
+	/* guarded by i_truncate_mutex */
+	unsigned int		i_wr_refcnt;
+};
+
+static inline struct zonefs_inode_info *ZONEFS_I(struct inode *inode)
+{
+	return container_of(inode, struct zonefs_inode_info, i_vnode);
+}
+
+static inline bool zonefs_zone_is_cnv(struct zonefs_zone *z)
+{
+	return z->z_flags & ZONEFS_ZONE_CNV;
+}
+
+static inline bool zonefs_zone_is_seq(struct zonefs_zone *z)
+{
+	return !zonefs_zone_is_cnv(z);
+}
+
+static inline struct zonefs_zone *zonefs_inode_zone(struct inode *inode)
+{
+	return inode->i_private;
+}
+
+static inline bool zonefs_inode_is_cnv(struct inode *inode)
+{
+	return zonefs_zone_is_cnv(zonefs_inode_zone(inode));
+}
+
+static inline bool zonefs_inode_is_seq(struct inode *inode)
+{
+	return zonefs_zone_is_seq(zonefs_inode_zone(inode));
+}
+
+/*
+ * On-disk super block (block 0).
+ */
+#define ZONEFS_LABEL_LEN	64
+#define ZONEFS_UUID_SIZE	16
+#define ZONEFS_SUPER_SIZE	4096
+
+struct zonefs_super {
+
+	/* Magic number */
+	__le32		s_magic;
+
+	/* Checksum */
+	__le32		s_crc;
+
+	/* Volume label */
+	char		s_label[ZONEFS_LABEL_LEN];
+
+	/* 128-bit uuid */
+	__u8		s_uuid[ZONEFS_UUID_SIZE];
+
+	/* Features */
+	__le64		s_features;
+
+	/* UID/GID to use for files */
+	__le32		s_uid;
+	__le32		s_gid;
+
+	/* File permissions */
+	__le32		s_perm;
+
+	/* Padding to ZONEFS_SUPER_SIZE bytes */
+	__u8		s_reserved[3988];
+
+} __packed;
+
+/*
+ * Feature flags: specified in the s_features field of the on-disk super
+ * block struct zonefs_super and in-memory in the s_feartures field of
+ * struct zonefs_sb_info.
+ */
+enum zonefs_features {
+	/*
+	 * Aggregate contiguous conventional zones into a single file.
+	 */
+	ZONEFS_F_AGGRCNV = 1ULL << 0,
+	/*
+	 * Use super block specified UID for files instead of default 0.
+	 */
+	ZONEFS_F_UID = 1ULL << 1,
+	/*
+	 * Use super block specified GID for files instead of default 0.
+	 */
+	ZONEFS_F_GID = 1ULL << 2,
+	/*
+	 * Use super block specified file permissions instead of default 640.
+	 */
+	ZONEFS_F_PERM = 1ULL << 3,
+};
+
+#define ZONEFS_F_DEFINED_FEATURES \
+	(ZONEFS_F_AGGRCNV | ZONEFS_F_UID | ZONEFS_F_GID | ZONEFS_F_PERM)
+
+/*
+ * Mount options for zone write pointer error handling.
+ */
+#define ZONEFS_MNTOPT_ERRORS_RO		(1 << 0) /* Make zone file readonly */
+#define ZONEFS_MNTOPT_ERRORS_ZRO	(1 << 1) /* Make zone file offline */
+#define ZONEFS_MNTOPT_ERRORS_ZOL	(1 << 2) /* Make zone file offline */
+#define ZONEFS_MNTOPT_ERRORS_REPAIR	(1 << 3) /* Remount read-only */
+#define ZONEFS_MNTOPT_ERRORS_MASK	\
+	(ZONEFS_MNTOPT_ERRORS_RO | ZONEFS_MNTOPT_ERRORS_ZRO | \
+	 ZONEFS_MNTOPT_ERRORS_ZOL | ZONEFS_MNTOPT_ERRORS_REPAIR)
+#define ZONEFS_MNTOPT_EXPLICIT_OPEN	(1 << 4) /* Explicit open/close of zones on open/close */
+
+/*
+ * In-memory Super block information.
+ */
+struct zonefs_sb_info {
+
+	unsigned long		s_mount_opts;
+
+	spinlock_t		s_lock;
+
+	unsigned long long	s_features;
+	kuid_t			s_uid;
+	kgid_t			s_gid;
+	umode_t			s_perm;
+	uuid_t			s_uuid;
+	unsigned int		s_zone_sectors_shift;
+
+	struct zonefs_zone_group s_zgroup[ZONEFS_ZTYPE_MAX];
+
+	loff_t			s_blocks;
+	loff_t			s_used_blocks;
+
+	unsigned int		s_max_wro_seq_files;
+	atomic_t		s_wro_seq_files;
+
+	unsigned int		s_max_active_seq_files;
+	atomic_t		s_active_seq_files;
+
+	bool			s_sysfs_registered;
+	struct kobject		s_kobj;
+	struct completion	s_kobj_unregister;
+};
+
+static inline struct zonefs_sb_info *ZONEFS_SB(struct super_block *sb)
+{
+	return sb->s_fs_info;
+}
+
+#define zonefs_info(sb, format, args...)	\
+	pr_info("zonefs (%s): " format, sb->s_id, ## args)
+#define zonefs_err(sb, format, args...)		\
+	pr_err("zonefs (%s) ERROR: " format, sb->s_id, ## args)
+#define zonefs_warn(sb, format, args...)	\
+	pr_warn("zonefs (%s) WARNING: " format, sb->s_id, ## args)
+
+/* In super.c */
+void zonefs_inode_account_active(struct inode *inode);
+int zonefs_inode_zone_mgmt(struct inode *inode, enum req_op op);
+void zonefs_i_size_write(struct inode *inode, loff_t isize);
+void zonefs_update_stats(struct inode *inode, loff_t new_isize);
+void __zonefs_io_error(struct inode *inode, bool write);
+
+static inline void zonefs_io_error(struct inode *inode, bool write)
+{
+	struct zonefs_inode_info *zi = ZONEFS_I(inode);
+
+	mutex_lock(&zi->i_truncate_mutex);
+	__zonefs_io_error(inode, write);
+	mutex_unlock(&zi->i_truncate_mutex);
+}
+
+/* In super.c */
+extern const struct inode_operations zonefs_dir_inode_operations;
+extern const struct file_operations zonefs_dir_operations;
+
+/* In file.c */
+extern const struct address_space_operations zonefs_file_aops;
+extern const struct file_operations zonefs_file_operations;
+int zonefs_file_truncate(struct inode *inode, loff_t isize);
+
+/* In sysfs.c */
+int zonefs_sysfs_register(struct super_block *sb);
+void zonefs_sysfs_unregister(struct super_block *sb);
+int zonefs_sysfs_init(void);
+void zonefs_sysfs_exit(void);
+
+#endif