Adding upstream version 5.10.209.upstream/5.10.209upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1912 insertions, 0 deletions

diff --git a/fs/zonefs/super.c b/fs/zonefs/super.c
new file mode 100644
index 000000000..b9522eee1
--- /dev/null
+++ b/fs/zonefs/super.c
@@ -0,0 +1,1912 @@
+// 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/fs.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/parser.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 "zonefs.h"
+
+static inline int zonefs_zone_mgmt(struct inode *inode,
+				   enum req_opf op)
+{
+	struct zonefs_inode_info *zi = ZONEFS_I(inode);
+	int ret;
+
+	lockdep_assert_held(&zi->i_truncate_mutex);
+
+	/*
+	 * 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 && !zi->i_wpoffset)
+		op = REQ_OP_ZONE_RESET;
+
+	ret = blkdev_zone_mgmt(inode->i_sb->s_bdev, op, zi->i_zsector,
+			       zi->i_zone_size >> SECTOR_SHIFT, GFP_NOFS);
+	if (ret) {
+		zonefs_err(inode->i_sb,
+			   "Zone management operation %s at %llu failed %d\n",
+			   blk_op_str(op), zi->i_zsector, ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static inline void zonefs_i_size_write(struct inode *inode, loff_t isize)
+{
+	struct zonefs_inode_info *zi = ZONEFS_I(inode);
+
+	i_size_write(inode, isize);
+	/*
+	 * A full zone is no longer open/active and does not need
+	 * explicit closing.
+	 */
+	if (isize >= zi->i_max_size)
+		zi->i_flags &= ~ZONEFS_ZONE_OPEN;
+}
+
+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 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 = (zi->i_zsector << SECTOR_SHIFT) + iomap->offset;
+		iomap->length = isize - iomap->offset;
+	}
+	mutex_unlock(&zi->i_truncate_mutex);
+
+	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 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 > zi->i_max_size))
+		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(zi->i_ztype == ZONEFS_ZTYPE_SEQ &&
+			 !(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 unwriten beyond.
+	 */
+	mutex_lock(&zi->i_truncate_mutex);
+	iomap->bdev = inode->i_sb->s_bdev;
+	iomap->offset = ALIGN_DOWN(offset, sb->s_blocksize);
+	iomap->addr = (zi->i_zsector << SECTOR_SHIFT) + iomap->offset;
+	isize = i_size_read(inode);
+	if (iomap->offset >= isize) {
+		iomap->type = IOMAP_UNWRITTEN;
+		iomap->length = zi->i_max_size - iomap->offset;
+	} else {
+		iomap->type = IOMAP_MAPPED;
+		iomap->length = isize - iomap->offset;
+	}
+	mutex_unlock(&zi->i_truncate_mutex);
+
+	return 0;
+}
+
+static const struct iomap_ops zonefs_write_iomap_ops = {
+	.iomap_begin	= zonefs_write_iomap_begin,
+};
+
+static int zonefs_readpage(struct file *unused, struct page *page)
+{
+	return iomap_readpage(page, &zonefs_read_iomap_ops);
+}
+
+static void zonefs_readahead(struct readahead_control *rac)
+{
+	iomap_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 int zonefs_write_map_blocks(struct iomap_writepage_ctx *wpc,
+				   struct inode *inode, loff_t offset)
+{
+	struct zonefs_inode_info *zi = ZONEFS_I(inode);
+
+	if (WARN_ON_ONCE(zi->i_ztype != ZONEFS_ZTYPE_CNV))
+		return -EIO;
+	if (WARN_ON_ONCE(offset >= i_size_read(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)
+		return 0;
+
+	return zonefs_write_iomap_begin(inode, offset, zi->i_max_size - offset,
+					IOMAP_WRITE, &wpc->iomap, NULL);
+}
+
+static const struct iomap_writeback_ops zonefs_writeback_ops = {
+	.map_blocks		= zonefs_write_map_blocks,
+};
+
+static int zonefs_writepage(struct page *page, struct writeback_control *wbc)
+{
+	struct iomap_writepage_ctx wpc = { };
+
+	return iomap_writepage(page, wbc, &wpc, &zonefs_writeback_ops);
+}
+
+static int zonefs_writepages(struct address_space *mapping,
+			     struct writeback_control *wbc)
+{
+	struct iomap_writepage_ctx wpc = { };
+
+	return iomap_writepages(mapping, wbc, &wpc, &zonefs_writeback_ops);
+}
+
+static int zonefs_swap_activate(struct swap_info_struct *sis,
+				struct file *swap_file, sector_t *span)
+{
+	struct inode *inode = file_inode(swap_file);
+	struct zonefs_inode_info *zi = ZONEFS_I(inode);
+
+	if (zi->i_ztype != ZONEFS_ZTYPE_CNV) {
+		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);
+}
+
+static const struct address_space_operations zonefs_file_aops = {
+	.readpage		= zonefs_readpage,
+	.readahead		= zonefs_readahead,
+	.writepage		= zonefs_writepage,
+	.writepages		= zonefs_writepages,
+	.set_page_dirty		= iomap_set_page_dirty,
+	.releasepage		= iomap_releasepage,
+	.invalidatepage		= iomap_invalidatepage,
+	.migratepage		= iomap_migrate_page,
+	.is_partially_uptodate	= iomap_is_partially_uptodate,
+	.error_remove_page	= generic_error_remove_page,
+	.direct_IO		= noop_direct_IO,
+	.swap_activate		= zonefs_swap_activate,
+};
+
+static 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 and adjust its file inode access permissions for
+ * offline and readonly zones. Return the inode size corresponding to the
+ * amount of readable data in the zone.
+ */
+static loff_t zonefs_check_zone_condition(struct inode *inode,
+					  struct blk_zone *zone, bool warn,
+					  bool mount)
+{
+	struct zonefs_inode_info *zi = ZONEFS_I(inode);
+
+	switch (zone->cond) {
+	case BLK_ZONE_COND_OFFLINE:
+		/*
+		 * Dead zone: make the inode immutable, disable all accesses
+		 * and set the file size to 0 (zone wp set to zone start).
+		 */
+		if (warn)
+			zonefs_warn(inode->i_sb, "inode %lu: offline zone\n",
+				    inode->i_ino);
+		inode->i_flags |= S_IMMUTABLE;
+		inode->i_mode &= ~0777;
+		zone->wp = zone->start;
+		return 0;
+	case BLK_ZONE_COND_READONLY:
+		/*
+		 * The write pointer of read-only zones is invalid. If such a
+		 * zone is found during mount, the file size cannot be retrieved
+		 * so we treat the zone as offline (mount == true case).
+		 * Otherwise, keep the file size as it was when last updated
+		 * so that the user can recover data. In both cases, writes are
+		 * always disabled for the zone.
+		 */
+		if (warn)
+			zonefs_warn(inode->i_sb, "inode %lu: read-only zone\n",
+				    inode->i_ino);
+		inode->i_flags |= S_IMMUTABLE;
+		if (mount) {
+			zone->cond = BLK_ZONE_COND_OFFLINE;
+			inode->i_mode &= ~0777;
+			zone->wp = zone->start;
+			return 0;
+		}
+		inode->i_mode &= ~0222;
+		return i_size_read(inode);
+	case BLK_ZONE_COND_FULL:
+		/* The write pointer of full zones is invalid. */
+		return zi->i_max_size;
+	default:
+		if (zi->i_ztype == ZONEFS_ZTYPE_CNV)
+			return zi->i_max_size;
+		return (zone->wp - zone->start) << SECTOR_SHIFT;
+	}
+}
+
+struct zonefs_ioerr_data {
+	struct inode	*inode;
+	bool		write;
+};
+
+static int zonefs_io_error_cb(struct blk_zone *zone, unsigned int idx,
+			      void *data)
+{
+	struct zonefs_ioerr_data *err = data;
+	struct inode *inode = err->inode;
+	struct zonefs_inode_info *zi = ZONEFS_I(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 writen in the zone (data_size).
+	 */
+	data_size = zonefs_check_zone_condition(inode, zone, true, false);
+	isize = i_size_read(inode);
+	if (zone->cond != BLK_ZONE_COND_OFFLINE &&
+	    zone->cond != BLK_ZONE_COND_READONLY &&
+	    !err->write && isize == data_size)
+		return 0;
+
+	/*
+	 * 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 writen 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 (zi->i_ztype == ZONEFS_ZTYPE_SEQ && isize != data_size)
+		zonefs_warn(sb, "inode %lu: 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 (zone->cond == BLK_ZONE_COND_OFFLINE ||
+	    sbi->s_mount_opts & ZONEFS_MNTOPT_ERRORS_ZOL) {
+		zonefs_warn(sb, "inode %lu: read/write access disabled\n",
+			    inode->i_ino);
+		if (zone->cond != BLK_ZONE_COND_OFFLINE) {
+			zone->cond = BLK_ZONE_COND_OFFLINE;
+			data_size = zonefs_check_zone_condition(inode, zone,
+								false, false);
+		}
+	} else if (zone->cond == BLK_ZONE_COND_READONLY ||
+		   sbi->s_mount_opts & ZONEFS_MNTOPT_ERRORS_ZRO) {
+		zonefs_warn(sb, "inode %lu: write access disabled\n",
+			    inode->i_ino);
+		if (zone->cond != BLK_ZONE_COND_READONLY) {
+			zone->cond = BLK_ZONE_COND_READONLY;
+			data_size = zonefs_check_zone_condition(inode, zone,
+								false, false);
+		}
+	} 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) &&
+	    (zone->cond == BLK_ZONE_COND_OFFLINE ||
+	     zone->cond == BLK_ZONE_COND_READONLY))
+		zi->i_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);
+	zi->i_wpoffset = data_size;
+
+	return 0;
+}
+
+/*
+ * 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).
+ */
+static void __zonefs_io_error(struct inode *inode, bool write)
+{
+	struct zonefs_inode_info *zi = ZONEFS_I(inode);
+	struct super_block *sb = inode->i_sb;
+	struct zonefs_sb_info *sbi = ZONEFS_SB(sb);
+	unsigned int noio_flag;
+	unsigned int nr_zones = 1;
+	struct zonefs_ioerr_data err = {
+		.inode = inode,
+		.write = write,
+	};
+	int ret;
+
+	/*
+	 * The only files that have more than one zone are conventional zone
+	 * files with aggregated conventional zones, for which the inode zone
+	 * size is always larger than the device zone size.
+	 */
+	if (zi->i_zone_size > bdev_zone_sectors(sb->s_bdev))
+		nr_zones = zi->i_zone_size >>
+			(sbi->s_zone_sectors_shift + SECTOR_SHIFT);
+
+	/*
+	 * 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, zi->i_zsector, nr_zones,
+				  zonefs_io_error_cb, &err);
+	if (ret != nr_zones)
+		zonefs_err(sb, "Get inode %lu zone information failed %d\n",
+			   inode->i_ino, ret);
+	memalloc_noio_restore(noio_flag);
+}
+
+static 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);
+}
+
+static int zonefs_file_truncate(struct inode *inode, loff_t isize)
+{
+	struct zonefs_inode_info *zi = ZONEFS_I(inode);
+	loff_t old_isize;
+	enum req_opf 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 (zi->i_ztype != ZONEFS_ZTYPE_SEQ)
+		return -EPERM;
+
+	if (!isize)
+		op = REQ_OP_ZONE_RESET;
+	else if (isize == zi->i_max_size)
+		op = REQ_OP_ZONE_FINISH;
+	else
+		return -EPERM;
+
+	inode_dio_wait(inode);
+
+	/* Serialize against page faults */
+	down_write(&zi->i_mmap_sem);
+
+	/* 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_zone_mgmt(inode, op);
+	if (ret)
+		goto unlock;
+
+	/*
+	 * If the mount option ZONEFS_MNTOPT_EXPLICIT_OPEN is set,
+	 * take care of open zones.
+	 */
+	if (zi->i_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_zone_mgmt(inode, REQ_OP_ZONE_OPEN);
+		else
+			zi->i_flags &= ~ZONEFS_ZONE_OPEN;
+	}
+
+	zonefs_update_stats(inode, isize);
+	truncate_setsize(inode, isize);
+	zi->i_wpoffset = isize;
+
+unlock:
+	mutex_unlock(&zi->i_truncate_mutex);
+	up_write(&zi->i_mmap_sem);
+
+	return ret;
+}
+
+static int zonefs_inode_setattr(struct dentry *dentry, struct iattr *iattr)
+{
+	struct inode *inode = d_inode(dentry);
+	int ret;
+
+	if (unlikely(IS_IMMUTABLE(inode)))
+		return -EPERM;
+
+	ret = setattr_prepare(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(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(inode, iattr);
+
+	return 0;
+}
+
+static const struct inode_operations zonefs_file_inode_operations = {
+	.setattr	= zonefs_inode_setattr,
+};
+
+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_I(inode)->i_ztype == ZONEFS_ZTYPE_CNV)
+		ret = file_write_and_wait_range(file, start, end);
+	if (!ret)
+		ret = blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL);
+
+	if (ret)
+		zonefs_io_error(inode, true);
+
+	return ret;
+}
+
+static vm_fault_t zonefs_filemap_fault(struct vm_fault *vmf)
+{
+	struct zonefs_inode_info *zi = ZONEFS_I(file_inode(vmf->vma->vm_file));
+	vm_fault_t ret;
+
+	down_read(&zi->i_mmap_sem);
+	ret = filemap_fault(vmf);
+	up_read(&zi->i_mmap_sem);
+
+	return ret;
+}
+
+static vm_fault_t zonefs_filemap_page_mkwrite(struct vm_fault *vmf)
+{
+	struct inode *inode = file_inode(vmf->vma->vm_file);
+	struct zonefs_inode_info *zi = ZONEFS_I(inode);
+	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 (WARN_ON_ONCE(zi->i_ztype != ZONEFS_ZTYPE_CNV))
+		return VM_FAULT_NOPAGE;
+
+	sb_start_pagefault(inode->i_sb);
+	file_update_time(vmf->vma->vm_file);
+
+	/* Serialize against truncates */
+	down_read(&zi->i_mmap_sem);
+	ret = iomap_page_mkwrite(vmf, &zonefs_write_iomap_ops);
+	up_read(&zi->i_mmap_sem);
+
+	sb_end_pagefault(inode->i_sb);
+	return ret;
+}
+
+static const struct vm_operations_struct zonefs_file_vm_ops = {
+	.fault		= zonefs_filemap_fault,
+	.map_pages	= filemap_map_pages,
+	.page_mkwrite	= zonefs_filemap_page_mkwrite,
+};
+
+static int zonefs_file_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	/*
+	 * 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_I(file_inode(file))->i_ztype == ZONEFS_ZTYPE_SEQ &&
+	    (vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))
+		return -EINVAL;
+
+	file_accessed(file);
+	vma->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) {
+		zonefs_io_error(inode, true);
+		return error;
+	}
+
+	if (size && zi->i_ztype != ZONEFS_ZTYPE_CNV) {
+		/*
+		 * 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,
+};
+
+static ssize_t zonefs_file_dio_append(struct kiocb *iocb, struct iov_iter *from)
+{
+	struct inode *inode = file_inode(iocb->ki_filp);
+	struct zonefs_inode_info *zi = ZONEFS_I(inode);
+	struct block_device *bdev = inode->i_sb->s_bdev;
+	unsigned int max;
+	struct bio *bio;
+	ssize_t size;
+	int nr_pages;
+	ssize_t ret;
+
+	max = queue_max_zone_append_sectors(bdev_get_queue(bdev));
+	max = ALIGN_DOWN(max << SECTOR_SHIFT, inode->i_sb->s_blocksize);
+	iov_iter_truncate(from, max);
+
+	nr_pages = iov_iter_npages(from, BIO_MAX_PAGES);
+	if (!nr_pages)
+		return 0;
+
+	bio = bio_alloc_bioset(GFP_NOFS, nr_pages, &fs_bio_set);
+	if (!bio)
+		return -ENOMEM;
+
+	bio_set_dev(bio, bdev);
+	bio->bi_iter.bi_sector = zi->i_zsector;
+	bio->bi_write_hint = iocb->ki_hint;
+	bio->bi_ioprio = iocb->ki_ioprio;
+	bio->bi_opf = REQ_OP_ZONE_APPEND | REQ_SYNC | REQ_IDLE;
+	if (iocb->ki_flags & IOCB_DSYNC)
+		bio->bi_opf |= REQ_FUA;
+
+	ret = bio_iov_iter_get_pages(bio, from);
+	if (unlikely(ret))
+		goto out_release;
+
+	size = bio->bi_iter.bi_size;
+	task_io_account_write(size);
+
+	if (iocb->ki_flags & IOCB_HIPRI)
+		bio_set_polled(bio, iocb);
+
+	ret = submit_bio_wait(bio);
+
+	/*
+	 * If the file zone was written underneath the file system, the zone
+	 * write pointer may not be where we expect it to be, but the zone
+	 * append write can still succeed. So check manually that we wrote where
+	 * we intended to, that is, at zi->i_wpoffset.
+	 */
+	if (!ret) {
+		sector_t wpsector =
+			zi->i_zsector + (zi->i_wpoffset >> SECTOR_SHIFT);
+
+		if (bio->bi_iter.bi_sector != wpsector) {
+			zonefs_warn(inode->i_sb,
+				"Corrupted write pointer %llu for zone at %llu\n",
+				bio->bi_iter.bi_sector, zi->i_zsector);
+			ret = -EIO;
+		}
+	}
+
+	zonefs_file_write_dio_end_io(iocb, size, ret, 0);
+
+out_release:
+	bio_release_pages(bio, false);
+	bio_put(bio);
+
+	if (ret >= 0) {
+		iocb->ki_pos += size;
+		return size;
+	}
+
+	return ret;
+}
+
+/*
+ * 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_inode_info *zi = ZONEFS_I(inode);
+	loff_t limit = rlimit(RLIMIT_FSIZE);
+	loff_t max_size = zi->i_max_size;
+
+	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);
+	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 (zi->i_ztype != ZONEFS_ZTYPE_SEQ)
+			return -EINVAL;
+		mutex_lock(&zi->i_truncate_mutex);
+		iocb->ki_pos = zi->i_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 super_block *sb = inode->i_sb;
+	bool sync = is_sync_kiocb(iocb);
+	bool append = false;
+	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 (zi->i_ztype == ZONEFS_ZTYPE_SEQ && !sync &&
+	    (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 (zi->i_ztype == ZONEFS_ZTYPE_SEQ) {
+		mutex_lock(&zi->i_truncate_mutex);
+		if (iocb->ki_pos != zi->i_wpoffset) {
+			mutex_unlock(&zi->i_truncate_mutex);
+			ret = -EINVAL;
+			goto inode_unlock;
+		}
+		mutex_unlock(&zi->i_truncate_mutex);
+		append = sync;
+	}
+
+	if (append)
+		ret = zonefs_file_dio_append(iocb, from);
+	else
+		ret = iomap_dio_rw(iocb, from, &zonefs_write_iomap_ops,
+				   &zonefs_write_dio_ops, sync);
+	if (zi->i_ztype == ZONEFS_ZTYPE_SEQ &&
+	    (ret > 0 || ret == -EIOCBQUEUED)) {
+		if (ret > 0)
+			count = ret;
+		mutex_lock(&zi->i_truncate_mutex);
+		zi->i_wpoffset += count;
+		mutex_unlock(&zi->i_truncate_mutex);
+	}
+
+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);
+	struct zonefs_inode_info *zi = ZONEFS_I(inode);
+	ssize_t ret;
+
+	/*
+	 * Direct IO writes are mandatory for sequential zone files so that the
+	 * write IO issuing order is preserved.
+	 */
+	if (zi->i_ztype != ZONEFS_ZTYPE_CNV)
+		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);
+	if (ret > 0)
+		iocb->ki_pos += ret;
+	else 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);
+
+	if (unlikely(IS_IMMUTABLE(inode)))
+		return -EPERM;
+
+	if (sb_rdonly(inode->i_sb))
+		return -EROFS;
+
+	/* Write operations beyond the zone size are not allowed */
+	if (iocb->ki_pos >= ZONEFS_I(inode)->i_max_size)
+		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 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 >= zi->i_max_size)
+		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, is_sync_kiocb(iocb));
+	} 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 inline bool zonefs_file_use_exp_open(struct inode *inode, struct file *file)
+{
+	struct zonefs_inode_info *zi = ZONEFS_I(inode);
+	struct zonefs_sb_info *sbi = ZONEFS_SB(inode->i_sb);
+
+	if (!(sbi->s_mount_opts & ZONEFS_MNTOPT_EXPLICIT_OPEN))
+		return false;
+
+	if (zi->i_ztype != ZONEFS_ZTYPE_SEQ)
+		return false;
+
+	if (!(file->f_mode & FMODE_WRITE))
+		return false;
+
+	return true;
+}
+
+static int zonefs_open_zone(struct inode *inode)
+{
+	struct zonefs_inode_info *zi = ZONEFS_I(inode);
+	struct zonefs_sb_info *sbi = ZONEFS_SB(inode->i_sb);
+	int ret = 0;
+
+	mutex_lock(&zi->i_truncate_mutex);
+
+	if (!zi->i_wr_refcnt) {
+		if (atomic_inc_return(&sbi->s_open_zones) > sbi->s_max_open_zones) {
+			atomic_dec(&sbi->s_open_zones);
+			ret = -EBUSY;
+			goto unlock;
+		}
+
+		if (i_size_read(inode) < zi->i_max_size) {
+			ret = zonefs_zone_mgmt(inode, REQ_OP_ZONE_OPEN);
+			if (ret) {
+				atomic_dec(&sbi->s_open_zones);
+				goto unlock;
+			}
+			zi->i_flags |= ZONEFS_ZONE_OPEN;
+		}
+	}
+
+	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;
+
+	ret = generic_file_open(inode, file);
+	if (ret)
+		return ret;
+
+	if (zonefs_file_use_exp_open(inode, file))
+		return zonefs_open_zone(inode);
+
+	return 0;
+}
+
+static void zonefs_close_zone(struct inode *inode)
+{
+	struct zonefs_inode_info *zi = ZONEFS_I(inode);
+	int ret = 0;
+
+	mutex_lock(&zi->i_truncate_mutex);
+	zi->i_wr_refcnt--;
+	if (!zi->i_wr_refcnt) {
+		struct zonefs_sb_info *sbi = ZONEFS_SB(inode->i_sb);
+		struct super_block *sb = inode->i_sb;
+
+		/*
+		 * If the file zone is full, it is not open anymore and we only
+		 * need to decrement the open count.
+		 */
+		if (!(zi->i_flags & ZONEFS_ZONE_OPEN))
+			goto dec;
+
+		ret = zonefs_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 (zi->i_flags & ZONEFS_ZONE_OPEN &&
+			    !(sb->s_flags & SB_RDONLY)) {
+				zonefs_warn(sb, "closing zone failed, remounting filesystem read-only\n");
+				sb->s_flags |= SB_RDONLY;
+			}
+		}
+		zi->i_flags &= ~ZONEFS_ZONE_OPEN;
+dec:
+		atomic_dec(&sbi->s_open_zones);
+	}
+	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_file_use_exp_open(inode, file))
+		zonefs_close_zone(inode);
+
+	return 0;
+}
+
+static const struct file_operations zonefs_file_operations = {
+	.open		= zonefs_file_open,
+	.release	= zonefs_file_release,
+	.fsync		= zonefs_file_fsync,
+	.mmap		= zonefs_file_mmap,
+	.llseek		= zonefs_file_llseek,
+	.read_iter	= zonefs_file_read_iter,
+	.write_iter	= zonefs_file_write_iter,
+	.splice_read	= generic_file_splice_read,
+	.splice_write	= iter_file_splice_write,
+	.iopoll		= iomap_dio_iopoll,
+};
+
+static struct kmem_cache *zonefs_inode_cachep;
+
+static struct inode *zonefs_alloc_inode(struct super_block *sb)
+{
+	struct zonefs_inode_info *zi;
+
+	zi = kmem_cache_alloc(zonefs_inode_cachep, GFP_KERNEL);
+	if (!zi)
+		return NULL;
+
+	inode_init_once(&zi->i_vnode);
+	mutex_init(&zi->i_truncate_mutex);
+	init_rwsem(&zi->i_mmap_sem);
+	zi->i_wr_refcnt = 0;
+	zi->i_flags = 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;
+	u64 fsid;
+
+	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_nr_files[t])
+			buf->f_files += sbi->s_nr_files[t] + 1;
+	}
+	buf->f_ffree = 0;
+
+	spin_unlock(&sbi->s_lock);
+
+	fsid = le64_to_cpup((void *)sbi->s_uuid.b) ^
+		le64_to_cpup((void *)sbi->s_uuid.b + sizeof(u64));
+	buf->f_fsid = u64_to_fsid(fsid);
+
+	return 0;
+}
+
+enum {
+	Opt_errors_ro, Opt_errors_zro, Opt_errors_zol, Opt_errors_repair,
+	Opt_explicit_open, Opt_err,
+};
+
+static const match_table_t tokens = {
+	{ Opt_errors_ro,	"errors=remount-ro"},
+	{ Opt_errors_zro,	"errors=zone-ro"},
+	{ Opt_errors_zol,	"errors=zone-offline"},
+	{ Opt_errors_repair,	"errors=repair"},
+	{ Opt_explicit_open,	"explicit-open" },
+	{ Opt_err,		NULL}
+};
+
+static int zonefs_parse_options(struct super_block *sb, char *options)
+{
+	struct zonefs_sb_info *sbi = ZONEFS_SB(sb);
+	substring_t args[MAX_OPT_ARGS];
+	char *p;
+
+	if (!options)
+		return 0;
+
+	while ((p = strsep(&options, ",")) != NULL) {
+		int token;
+
+		if (!*p)
+			continue;
+
+		token = match_token(p, tokens, args);
+		switch (token) {
+		case Opt_errors_ro:
+			sbi->s_mount_opts &= ~ZONEFS_MNTOPT_ERRORS_MASK;
+			sbi->s_mount_opts |= ZONEFS_MNTOPT_ERRORS_RO;
+			break;
+		case Opt_errors_zro:
+			sbi->s_mount_opts &= ~ZONEFS_MNTOPT_ERRORS_MASK;
+			sbi->s_mount_opts |= ZONEFS_MNTOPT_ERRORS_ZRO;
+			break;
+		case Opt_errors_zol:
+			sbi->s_mount_opts &= ~ZONEFS_MNTOPT_ERRORS_MASK;
+			sbi->s_mount_opts |= ZONEFS_MNTOPT_ERRORS_ZOL;
+			break;
+		case Opt_errors_repair:
+			sbi->s_mount_opts &= ~ZONEFS_MNTOPT_ERRORS_MASK;
+			sbi->s_mount_opts |= ZONEFS_MNTOPT_ERRORS_REPAIR;
+			break;
+		case Opt_explicit_open:
+			sbi->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_remount(struct super_block *sb, int *flags, char *data)
+{
+	sync_filesystem(sb);
+
+	return zonefs_parse_options(sb, data);
+}
+
+static const struct super_operations zonefs_sops = {
+	.alloc_inode	= zonefs_alloc_inode,
+	.free_inode	= zonefs_free_inode,
+	.statfs		= zonefs_statfs,
+	.remount_fs	= zonefs_remount,
+	.show_options	= zonefs_show_options,
+};
+
+static const struct inode_operations zonefs_dir_inode_operations = {
+	.lookup		= simple_lookup,
+	.setattr	= zonefs_inode_setattr,
+};
+
+static void zonefs_init_dir_inode(struct inode *parent, struct inode *inode,
+				  enum zonefs_ztype type)
+{
+	struct super_block *sb = parent->i_sb;
+
+	inode->i_ino = blkdev_nr_zones(sb->s_bdev->bd_disk) + type + 1;
+	inode_init_owner(inode, parent, S_IFDIR | 0555);
+	inode->i_op = &zonefs_dir_inode_operations;
+	inode->i_fop = &simple_dir_operations;
+	set_nlink(inode, 2);
+	inc_nlink(parent);
+}
+
+static int zonefs_init_file_inode(struct inode *inode, struct blk_zone *zone,
+				  enum zonefs_ztype type)
+{
+	struct super_block *sb = inode->i_sb;
+	struct zonefs_sb_info *sbi = ZONEFS_SB(sb);
+	struct zonefs_inode_info *zi = ZONEFS_I(inode);
+	int ret = 0;
+
+	inode->i_ino = zone->start >> sbi->s_zone_sectors_shift;
+	inode->i_mode = S_IFREG | sbi->s_perm;
+
+	zi->i_ztype = type;
+	zi->i_zsector = zone->start;
+	zi->i_zone_size = zone->len << SECTOR_SHIFT;
+	if (zi->i_zone_size > bdev_zone_sectors(sb->s_bdev) << SECTOR_SHIFT &&
+	    !(sbi->s_features & ZONEFS_F_AGGRCNV)) {
+		zonefs_err(sb,
+			   "zone size %llu doesn't match device's zone sectors %llu\n",
+			   zi->i_zone_size,
+			   bdev_zone_sectors(sb->s_bdev) << SECTOR_SHIFT);
+		return -EINVAL;
+	}
+
+	zi->i_max_size = min_t(loff_t, MAX_LFS_FILESIZE,
+			       zone->capacity << SECTOR_SHIFT);
+	zi->i_wpoffset = zonefs_check_zone_condition(inode, zone, true, true);
+
+	inode->i_uid = sbi->s_uid;
+	inode->i_gid = sbi->s_gid;
+	inode->i_size = zi->i_wpoffset;
+	inode->i_blocks = zi->i_max_size >> SECTOR_SHIFT;
+
+	inode->i_op = &zonefs_file_inode_operations;
+	inode->i_fop = &zonefs_file_operations;
+	inode->i_mapping->a_ops = &zonefs_file_aops;
+
+	sb->s_maxbytes = max(zi->i_max_size, sb->s_maxbytes);
+	sbi->s_blocks += zi->i_max_size >> sb->s_blocksize_bits;
+	sbi->s_used_blocks += zi->i_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 (type == ZONEFS_ZTYPE_SEQ &&
+	    (zone->cond == BLK_ZONE_COND_IMP_OPEN ||
+	     zone->cond == BLK_ZONE_COND_EXP_OPEN)) {
+		mutex_lock(&zi->i_truncate_mutex);
+		ret = zonefs_zone_mgmt(inode, REQ_OP_ZONE_CLOSE);
+		mutex_unlock(&zi->i_truncate_mutex);
+	}
+
+	return ret;
+}
+
+static struct dentry *zonefs_create_inode(struct dentry *parent,
+					const char *name, struct blk_zone *zone,
+					enum zonefs_ztype type)
+{
+	struct inode *dir = d_inode(parent);
+	struct dentry *dentry;
+	struct inode *inode;
+	int ret = -ENOMEM;
+
+	dentry = d_alloc_name(parent, name);
+	if (!dentry)
+		return ERR_PTR(ret);
+
+	inode = new_inode(parent->d_sb);
+	if (!inode)
+		goto dput;
+
+	inode->i_ctime = inode->i_mtime = inode->i_atime = dir->i_ctime;
+	if (zone) {
+		ret = zonefs_init_file_inode(inode, zone, type);
+		if (ret) {
+			iput(inode);
+			goto dput;
+		}
+	} else {
+		zonefs_init_dir_inode(dir, inode, type);
+	}
+
+	d_add(dentry, inode);
+	dir->i_size++;
+
+	return dentry;
+
+dput:
+	dput(dentry);
+
+	return ERR_PTR(ret);
+}
+
+struct zonefs_zone_data {
+	struct super_block	*sb;
+	unsigned int		nr_zones[ZONEFS_ZTYPE_MAX];
+	struct blk_zone		*zones;
+};
+
+/*
+ * Create a zone group and populate it with zone files.
+ */
+static int zonefs_create_zgroup(struct zonefs_zone_data *zd,
+				enum zonefs_ztype type)
+{
+	struct super_block *sb = zd->sb;
+	struct zonefs_sb_info *sbi = ZONEFS_SB(sb);
+	struct blk_zone *zone, *next, *end;
+	const char *zgroup_name;
+	char *file_name;
+	struct dentry *dir, *dent;
+	unsigned int n = 0;
+	int ret;
+
+	/* If the group is empty, there is nothing to do */
+	if (!zd->nr_zones[type])
+		return 0;
+
+	file_name = kmalloc(ZONEFS_NAME_MAX, GFP_KERNEL);
+	if (!file_name)
+		return -ENOMEM;
+
+	if (type == ZONEFS_ZTYPE_CNV)
+		zgroup_name = "cnv";
+	else
+		zgroup_name = "seq";
+
+	dir = zonefs_create_inode(sb->s_root, zgroup_name, NULL, type);
+	if (IS_ERR(dir)) {
+		ret = PTR_ERR(dir);
+		goto free;
+	}
+
+	/*
+	 * The first zone contains the super block: skip it.
+	 */
+	end = zd->zones + blkdev_nr_zones(sb->s_bdev->bd_disk);
+	for (zone = &zd->zones[1]; zone < end; zone = next) {
+
+		next = zone + 1;
+		if (zonefs_zone_type(zone) != type)
+			continue;
+
+		/*
+		 * 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 (type == ZONEFS_ZTYPE_CNV &&
+		    (sbi->s_features & ZONEFS_F_AGGRCNV)) {
+			for (; next < end; next++) {
+				if (zonefs_zone_type(next) != type)
+					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;
+			}
+			if (zone->capacity != zone->len) {
+				zonefs_err(sb, "Invalid conventional zone capacity\n");
+				ret = -EINVAL;
+				goto free;
+			}
+		}
+
+		/*
+		 * Use the file number within its group as file name.
+		 */
+		snprintf(file_name, ZONEFS_NAME_MAX - 1, "%u", n);
+		dent = zonefs_create_inode(dir, file_name, zone, type);
+		if (IS_ERR(dent)) {
+			ret = PTR_ERR(dent);
+			goto free;
+		}
+
+		n++;
+	}
+
+	zonefs_info(sb, "Zone group \"%s\" has %u file%s\n",
+		    zgroup_name, n, n > 1 ? "s" : "");
+
+	sbi->s_nr_files[type] = n;
+	ret = 0;
+
+free:
+	kfree(file_name);
+
+	return ret;
+}
+
+static int zonefs_get_zone_info_cb(struct blk_zone *zone, unsigned int idx,
+				   void *data)
+{
+	struct zonefs_zone_data *zd = data;
+
+	/*
+	 * Count the number of usable zones: the first zone at index 0 contains
+	 * the super block and is ignored.
+	 */
+	switch (zone->type) {
+	case BLK_ZONE_TYPE_CONVENTIONAL:
+		zone->wp = zone->start + zone->len;
+		if (idx)
+			zd->nr_zones[ZONEFS_ZTYPE_CNV]++;
+		break;
+	case BLK_ZONE_TYPE_SEQWRITE_REQ:
+	case BLK_ZONE_TYPE_SEQWRITE_PREF:
+		if (idx)
+			zd->nr_zones[ZONEFS_ZTYPE_SEQ]++;
+		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 = kvcalloc(blkdev_nr_zones(bdev->bd_disk),
+			     sizeof(struct blk_zone), GFP_KERNEL);
+	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 != blkdev_nr_zones(bdev->bd_disk)) {
+		zonefs_err(zd->sb, "Invalid zone report (%d/%u zones)\n",
+			   ret, blkdev_nr_zones(bdev->bd_disk));
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static inline void zonefs_cleanup_zone_info(struct zonefs_zone_data *zd)
+{
+	kvfree(zd->zones);
+}
+
+/*
+ * 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;
+	struct page *page;
+	struct bio_vec bio_vec;
+	struct bio bio;
+	int ret;
+
+	page = alloc_page(GFP_KERNEL);
+	if (!page)
+		return -ENOMEM;
+
+	bio_init(&bio, &bio_vec, 1);
+	bio.bi_iter.bi_sector = 0;
+	bio.bi_opf = REQ_OP_READ;
+	bio_set_dev(&bio, sb->s_bdev);
+	bio_add_page(&bio, page, PAGE_SIZE, 0);
+
+	ret = submit_bio_wait(&bio);
+	if (ret)
+		goto free_page;
+
+	super = kmap(page);
+
+	ret = -EINVAL;
+	if (le32_to_cpu(super->s_magic) != ZONEFS_MAGIC)
+		goto unmap;
+
+	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 unmap;
+	}
+
+	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 unmap;
+	}
+
+	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 unmap;
+		}
+	}
+
+	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 unmap;
+		}
+	}
+
+	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 unmap;
+	}
+
+	import_uuid(&sbi->s_uuid, super->s_uuid);
+	ret = 0;
+
+unmap:
+	kunmap(page);
+free_page:
+	__free_page(page);
+
+	return ret;
+}
+
+/*
+ * 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, void *data, int silent)
+{
+	struct zonefs_zone_data zd;
+	struct zonefs_sb_info *sbi;
+	struct inode *inode;
+	enum zonefs_ztype t;
+	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(sizeof(*sbi), GFP_KERNEL);
+	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 physical sector size to ensure
+	 * that write operations on 512e devices (512B logical block and 4KB
+	 * physical block) are always aligned to the device physical blocks,
+	 * as mandated by the ZBC/ZAC specifications.
+	 */
+	sb_set_blocksize(sb, bdev_physical_block_size(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 = ZONEFS_MNTOPT_ERRORS_RO;
+	sbi->s_max_open_zones = bdev_max_open_zones(sb->s_bdev);
+	atomic_set(&sbi->s_open_zones, 0);
+
+	ret = zonefs_read_super(sb);
+	if (ret)
+		return ret;
+
+	ret = zonefs_parse_options(sb, data);
+	if (ret)
+		return ret;
+
+	memset(&zd, 0, sizeof(struct zonefs_zone_data));
+	zd.sb = sb;
+	ret = zonefs_get_zone_info(&zd);
+	if (ret)
+		goto cleanup;
+
+	zonefs_info(sb, "Mounting %u zones",
+		    blkdev_nr_zones(sb->s_bdev->bd_disk));
+
+	if (!sbi->s_max_open_zones &&
+	    sbi->s_mount_opts & ZONEFS_MNTOPT_EXPLICIT_OPEN) {
+		zonefs_info(sb, "No open zones limit. Ignoring explicit_open mount option\n");
+		sbi->s_mount_opts &= ~ZONEFS_MNTOPT_EXPLICIT_OPEN;
+	}
+
+	/* Create root directory inode */
+	ret = -ENOMEM;
+	inode = new_inode(sb);
+	if (!inode)
+		goto cleanup;
+
+	inode->i_ino = blkdev_nr_zones(sb->s_bdev->bd_disk);
+	inode->i_mode = S_IFDIR | 0555;
+	inode->i_ctime = inode->i_mtime = inode->i_atime = current_time(inode);
+	inode->i_op = &zonefs_dir_inode_operations;
+	inode->i_fop = &simple_dir_operations;
+	set_nlink(inode, 2);
+
+	sb->s_root = d_make_root(inode);
+	if (!sb->s_root)
+		goto cleanup;
+
+	/* Create and populate files in zone groups directories */
+	for (t = 0; t < ZONEFS_ZTYPE_MAX; t++) {
+		ret = zonefs_create_zgroup(&zd, t);
+		if (ret)
+			break;
+	}
+
+cleanup:
+	zonefs_cleanup_zone_info(&zd);
+
+	return ret;
+}
+
+static struct dentry *zonefs_mount(struct file_system_type *fs_type,
+				   int flags, const char *dev_name, void *data)
+{
+	return mount_bdev(fs_type, flags, dev_name, data, zonefs_fill_super);
+}
+
+static void zonefs_kill_super(struct super_block *sb)
+{
+	struct zonefs_sb_info *sbi = ZONEFS_SB(sb);
+
+	if (sb->s_root)
+		d_genocide(sb->s_root);
+	kill_block_super(sb);
+	kfree(sbi);
+}
+
+/*
+ * File system definition and registration.
+ */
+static struct file_system_type zonefs_type = {
+	.owner		= THIS_MODULE,
+	.name		= "zonefs",
+	.mount		= zonefs_mount,
+	.kill_sb	= zonefs_kill_super,
+	.fs_flags	= FS_REQUIRES_DEV,
+};
+
+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_MEM_SPREAD | 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 = register_filesystem(&zonefs_type);
+	if (ret) {
+		zonefs_destroy_inodecache();
+		return ret;
+	}
+
+	return 0;
+}
+
+static void __exit zonefs_exit(void)
+{
+	zonefs_destroy_inodecache();
+	unregister_filesystem(&zonefs_type);
+}
+
+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);