linux.git/fs/zonefs, branch v6.8 Linux kernel source tree zonefs: Improve error handling 2024-02-16T01:20:35+00:00 Damien Le Moal dlemoal@kernel.org 2024-02-08T08:26:59+00:00 14db5f64a971fce3d8ea35de4dfc7f443a3efb92 Write error handling is racy and can sometime lead to the error recovery path wrongly changing the inode size of a sequential zone file to an incorrect value which results in garbage data being readable at the end of a file. There are 2 problems: 1) zonefs_file_dio_write() updates a zone file write pointer offset after issuing a direct IO with iomap_dio_rw(). This update is done only if the IO succeed for synchronous direct writes. However, for asynchronous direct writes, the update is done without waiting for the IO completion so that the next asynchronous IO can be immediately issued. However, if an asynchronous IO completes with a failure right before the i_truncate_mutex lock protecting the update, the update may change the value of the inode write pointer offset that was corrected by the error path (zonefs_io_error() function). 2) zonefs_io_error() is called when a read or write error occurs. This function executes a report zone operation using the callback function zonefs_io_error_cb(), which does all the error recovery handling based on the current zone condition, write pointer position and according to the mount options being used. However, depending on the zoned device being used, a report zone callback may be executed in a context that is different from the context of __zonefs_io_error(). As a result, zonefs_io_error_cb() may be executed without the inode truncate mutex lock held, which can lead to invalid error processing. Fix both problems as follows: - Problem 1: Perform the inode write pointer offset update before a direct write is issued with iomap_dio_rw(). This is safe to do as partial direct writes are not supported (IOMAP_DIO_PARTIAL is not set) and any failed IO will trigger the execution of zonefs_io_error() which will correct the inode write pointer offset to reflect the current state of the one on the device. - Problem 2: Change zonefs_io_error_cb() into zonefs_handle_io_error() and call this function directly from __zonefs_io_error() after obtaining the zone information using blkdev_report_zones() with a simple callback function that copies to a local stack variable the struct blk_zone obtained from the device. This ensures that error handling is performed holding the inode truncate mutex. This change also simplifies error handling for conventional zone files by bypassing the execution of report zones entirely. This is safe to do because the condition of conventional zones cannot be read-only or offline and conventional zone files are always fully mapped with a constant file size. Reported-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com> Fixes: 8dcc1a9d90c1 ("fs: New zonefs file system") Cc: stable@vger.kernel.org Signed-off-by: Damien Le Moal <dlemoal@kernel.org> Tested-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com> 
Write error handling is racy and can sometime lead to the error recovery
path wrongly changing the inode size of a sequential zone file to an
incorrect value  which results in garbage data being readable at the end
of a file. There are 2 problems:

1) zonefs_file_dio_write() updates a zone file write pointer offset
   after issuing a direct IO with iomap_dio_rw(). This update is done
   only if the IO succeed for synchronous direct writes. However, for
   asynchronous direct writes, the update is done without waiting for
   the IO completion so that the next asynchronous IO can be
   immediately issued. However, if an asynchronous IO completes with a
   failure right before the i_truncate_mutex lock protecting the update,
   the update may change the value of the inode write pointer offset
   that was corrected by the error path (zonefs_io_error() function).

2) zonefs_io_error() is called when a read or write error occurs. This
   function executes a report zone operation using the callback function
   zonefs_io_error_cb(), which does all the error recovery handling
   based on the current zone condition, write pointer position and
   according to the mount options being used. However, depending on the
   zoned device being used, a report zone callback may be executed in a
   context that is different from the context of __zonefs_io_error(). As
   a result, zonefs_io_error_cb() may be executed without the inode
   truncate mutex lock held, which can lead to invalid error processing.

Fix both problems as follows:
- Problem 1: Perform the inode write pointer offset update before a
  direct write is issued with iomap_dio_rw(). This is safe to do as
  partial direct writes are not supported (IOMAP_DIO_PARTIAL is not
  set) and any failed IO will trigger the execution of zonefs_io_error()
  which will correct the inode write pointer offset to reflect the
  current state of the one on the device.
- Problem 2: Change zonefs_io_error_cb() into zonefs_handle_io_error()
  and call this function directly from __zonefs_io_error() after
  obtaining the zone information using blkdev_report_zones() with a
  simple callback function that copies to a local stack variable the
  struct blk_zone obtained from the device. This ensures that error
  handling is performed holding the inode truncate mutex.
  This change also simplifies error handling for conventional zone files
  by bypassing the execution of report zones entirely. This is safe to
  do because the condition of conventional zones cannot be read-only or
  offline and conventional zone files are always fully mapped with a
  constant file size.

Reported-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Fixes: 8dcc1a9d90c1 ("fs: New zonefs file system")
Cc: stable@vger.kernel.org
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Tested-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Merge tag 'pull-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2024-01-12T04:23:50+00:00 Linus Torvalds torvalds@linux-foundation.org 2024-01-12T04:23:50+00:00 488926926a1653adfda3f662355907c896524487 Pull misc filesystem updates from Al Viro: "Misc cleanups (the part that hadn't been picked by individual fs trees)" * tag 'pull-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: apparmorfs: don't duplicate kfree_link() orangefs: saner arguments passing in readdir guts ocfs2_find_match(): there's no such thing as NULL or negative ->d_parent reiserfs_add_entry(): get rid of pointless namelen checks __ocfs2_add_entry(), ocfs2_prepare_dir_for_insert(): namelen checks ext4_add_entry(): ->d_name.len is never 0 befs: d_obtain_alias(ERR_PTR(...)) will do the right thing affs: d_obtain_alias(ERR_PTR(...)) will do the right thing /proc/sys: use d_splice_alias() calling conventions to simplify failure exits hostfs: use d_splice_alias() calling conventions to simplify failure exits udf_fiiter_add_entry(): check for zero ->d_name.len is bogus... udf: d_obtain_alias(ERR_PTR(...)) will do the right thing... udf: d_splice_alias() will do the right thing on ERR_PTR() inode nfsd: kill stale comment about simple_fill_super() requirements bfs_add_entry(): get rid of pointless ->d_name.len checks nilfs2: d_obtain_alias(ERR_PTR(...)) will do the right thing... zonefs: d_splice_alias() will do the right thing on ERR_PTR() inode 
Pull misc filesystem updates from Al Viro:
 "Misc cleanups (the part that hadn't been picked by individual fs
  trees)"

* tag 'pull-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  apparmorfs: don't duplicate kfree_link()
  orangefs: saner arguments passing in readdir guts
  ocfs2_find_match(): there's no such thing as NULL or negative ->d_parent
  reiserfs_add_entry(): get rid of pointless namelen checks
  __ocfs2_add_entry(), ocfs2_prepare_dir_for_insert(): namelen checks
  ext4_add_entry(): ->d_name.len is never 0
  befs: d_obtain_alias(ERR_PTR(...)) will do the right thing
  affs: d_obtain_alias(ERR_PTR(...)) will do the right thing
  /proc/sys: use d_splice_alias() calling conventions to simplify failure exits
  hostfs: use d_splice_alias() calling conventions to simplify failure exits
  udf_fiiter_add_entry(): check for zero ->d_name.len is bogus...
  udf: d_obtain_alias(ERR_PTR(...)) will do the right thing...
  udf: d_splice_alias() will do the right thing on ERR_PTR() inode
  nfsd: kill stale comment about simple_fill_super() requirements
  bfs_add_entry(): get rid of pointless ->d_name.len checks
  nilfs2: d_obtain_alias(ERR_PTR(...)) will do the right thing...
  zonefs: d_splice_alias() will do the right thing on ERR_PTR() inode
zonefs: d_splice_alias() will do the right thing on ERR_PTR() inode 2023-12-20T17:08:03+00:00 Al Viro viro@zeniv.linux.org.uk 2023-11-11T06:13:58+00:00 00488aa21150053a568343df2aca10a33559d7d8 Acked-by: Damien Le Moal <dlemoal@kernel.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> 
Acked-by: Damien Le Moal <dlemoal@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
fs: convert error_remove_page to error_remove_folio 2023-12-11T00:51:42+00:00 Matthew Wilcox (Oracle) willy@infradead.org 2023-11-17T16:14:47+00:00 af7628d6ec196999175ecb3fdb38336489b0f88a There were already assertions that we were not passing a tail page to error_remove_page(), so make the compiler enforce that by converting everything to pass and use a folio. Link: https://lkml.kernel.org/r/20231117161447.2461643-7-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Naoya Horiguchi <naoya.horiguchi@nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> 
There were already assertions that we were not passing a tail page to
error_remove_page(), so make the compiler enforce that by converting
everything to pass and use a folio.

Link: https://lkml.kernel.org/r/20231117161447.2461643-7-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
zonefs: convert to new timestamp accessors 2023-10-18T12:08:29+00:00 Jeff Layton jlayton@kernel.org 2023-10-04T18:53:03+00:00 8df379a340e765af10c33de90fd954d6d7dcd8a2 Convert to using the new inode timestamp accessor functions. Signed-off-by: Jeff Layton <jlayton@kernel.org> Link: https://lore.kernel.org/r/20231004185347.80880-76-jlayton@kernel.org Signed-off-by: Christian Brauner <brauner@kernel.org> 
Convert to using the new inode timestamp accessor functions.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://lore.kernel.org/r/20231004185347.80880-76-jlayton@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Merge tag 'iomap-6.6-merge-3' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux 2023-08-28T18:59:52+00:00 Linus Torvalds torvalds@linux-foundation.org 2023-08-28T18:59:52+00:00 6016fc9162245c5b109305841f76cca59c20a273 Pull iomap updates from Darrick Wong: "We've got some big changes for this release -- I'm very happy to be landing willy's work to enable large folios for the page cache for general read and write IOs when the fs can make contiguous space allocations, and Ritesh's work to track sub-folio dirty state to eliminate the write amplification problems inherent in using large folios. As a bonus, io_uring can now process write completions in the caller's context instead of bouncing through a workqueue, which should reduce io latency dramatically. IOWs, XFS should see a nice performance bump for both IO paths. Summary: - Make large writes to the page cache fill sparse parts of the cache with large folios, then use large memcpy calls for the large folio. - Track the per-block dirty state of each large folio so that a buffered write to a single byte on a large folio does not result in a (potentially) multi-megabyte writeback IO. - Allow some directio completions to be performed in the initiating task's context instead of punting through a workqueue. This will reduce latency for some io_uring requests" * tag 'iomap-6.6-merge-3' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux: (26 commits) iomap: support IOCB_DIO_CALLER_COMP io_uring/rw: add write support for IOCB_DIO_CALLER_COMP fs: add IOCB flags related to passing back dio completions iomap: add IOMAP_DIO_INLINE_COMP iomap: only set iocb->private for polled bio iomap: treat a write through cache the same as FUA iomap: use an unsigned type for IOMAP_DIO_* defines iomap: cleanup up iomap_dio_bio_end_io() iomap: Add per-block dirty state tracking to improve performance iomap: Allocate ifs in ->write_begin() early iomap: Refactor iomap_write_delalloc_punch() function out iomap: Use iomap_punch_t typedef iomap: Fix possible overflow condition in iomap_write_delalloc_scan iomap: Add some uptodate state handling helpers for ifs state bitmap iomap: Drop ifs argument from iomap_set_range_uptodate() iomap: Rename iomap_page to iomap_folio_state and others iomap: Copy larger chunks from userspace iomap: Create large folios in the buffered write path filemap: Allow __filemap_get_folio to allocate large folios filemap: Add fgf_t typedef ... 
Pull iomap updates from Darrick Wong:
 "We've got some big changes for this release -- I'm very happy to be
  landing willy's work to enable large folios for the page cache for
  general read and write IOs when the fs can make contiguous space
  allocations, and Ritesh's work to track sub-folio dirty state to
  eliminate the write amplification problems inherent in using large
  folios.

  As a bonus, io_uring can now process write completions in the caller's
  context instead of bouncing through a workqueue, which should reduce
  io latency dramatically. IOWs, XFS should see a nice performance bump
  for both IO paths.

  Summary:

   - Make large writes to the page cache fill sparse parts of the cache
     with large folios, then use large memcpy calls for the large folio.

   - Track the per-block dirty state of each large folio so that a
     buffered write to a single byte on a large folio does not result in
     a (potentially) multi-megabyte writeback IO.

   - Allow some directio completions to be performed in the initiating
     task's context instead of punting through a workqueue. This will
     reduce latency for some io_uring requests"

* tag 'iomap-6.6-merge-3' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux: (26 commits)
  iomap: support IOCB_DIO_CALLER_COMP
  io_uring/rw: add write support for IOCB_DIO_CALLER_COMP
  fs: add IOCB flags related to passing back dio completions
  iomap: add IOMAP_DIO_INLINE_COMP
  iomap: only set iocb->private for polled bio
  iomap: treat a write through cache the same as FUA
  iomap: use an unsigned type for IOMAP_DIO_* defines
  iomap: cleanup up iomap_dio_bio_end_io()
  iomap: Add per-block dirty state tracking to improve performance
  iomap: Allocate ifs in ->write_begin() early
  iomap: Refactor iomap_write_delalloc_punch() function out
  iomap: Use iomap_punch_t typedef
  iomap: Fix possible overflow condition in iomap_write_delalloc_scan
  iomap: Add some uptodate state handling helpers for ifs state bitmap
  iomap: Drop ifs argument from iomap_set_range_uptodate()
  iomap: Rename iomap_page to iomap_folio_state and others
  iomap: Copy larger chunks from userspace
  iomap: Create large folios in the buffered write path
  filemap: Allow __filemap_get_folio to allocate large folios
  filemap: Add fgf_t typedef
  ...
Merge tag 'v6.6-vfs.ctime' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs 2023-08-28T16:31:32+00:00 Linus Torvalds torvalds@linux-foundation.org 2023-08-28T16:31:32+00:00 615e95831ec3d428cc554ac12e9439e2d66038d3 Pull vfs timestamp updates from Christian Brauner: "This adds VFS support for multi-grain timestamps and converts tmpfs, xfs, ext4, and btrfs to use them. This carries acks from all relevant filesystems. The VFS always uses coarse-grained timestamps when updating the ctime and mtime after a change. This has the benefit of allowing filesystems to optimize away a lot of metadata updates, down to around 1 per jiffy, even when a file is under heavy writes. Unfortunately, this has always been an issue when we're exporting via NFSv3, which relies on timestamps to validate caches. A lot of changes can happen in a jiffy, so timestamps aren't sufficient to help the client decide to invalidate the cache. Even with NFSv4, a lot of exported filesystems don't properly support a change attribute and are subject to the same problems with timestamp granularity. Other applications have similar issues with timestamps (e.g., backup applications). If we were to always use fine-grained timestamps, that would improve the situation, but that becomes rather expensive, as the underlying filesystem would have to log a lot more metadata updates. This introduces fine-grained timestamps that are used when they are actively queried. This uses the 31st bit of the ctime tv_nsec field to indicate that something has queried the inode for the mtime or ctime. When this flag is set, on the next mtime or ctime update, the kernel will fetch a fine-grained timestamp instead of the usual coarse-grained one. As POSIX generally mandates that when the mtime changes, the ctime must also change the kernel always stores normalized ctime values, so only the first 30 bits of the tv_nsec field are ever used. Filesytems can opt into this behavior by setting the FS_MGTIME flag in the fstype. Filesystems that don't set this flag will continue to use coarse-grained timestamps. Various preparatory changes, fixes and cleanups are included: - Fixup all relevant places where POSIX requires updating ctime together with mtime. This is a wide-range of places and all maintainers provided necessary Acks. - Add new accessors for inode->i_ctime directly and change all callers to rely on them. Plain accesses to inode->i_ctime are now gone and it is accordingly rename to inode->__i_ctime and commented as requiring accessors. - Extend generic_fillattr() to pass in a request mask mirroring in a sense the statx() uapi. This allows callers to pass in a request mask to only get a subset of attributes filled in. - Rework timestamp updates so it's possible to drop the @now parameter the update_time() inode operation and associated helpers. - Add inode_update_timestamps() and convert all filesystems to it removing a bunch of open-coding" * tag 'v6.6-vfs.ctime' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (107 commits) btrfs: convert to multigrain timestamps ext4: switch to multigrain timestamps xfs: switch to multigrain timestamps tmpfs: add support for multigrain timestamps fs: add infrastructure for multigrain timestamps fs: drop the timespec64 argument from update_time xfs: have xfs_vn_update_time gets its own timestamp fat: make fat_update_time get its own timestamp fat: remove i_version handling from fat_update_time ubifs: have ubifs_update_time use inode_update_timestamps btrfs: have it use inode_update_timestamps fs: drop the timespec64 arg from generic_update_time fs: pass the request_mask to generic_fillattr fs: remove silly warning from current_time gfs2: fix timestamp handling on quota inodes fs: rename i_ctime field to __i_ctime selinux: convert to ctime accessor functions security: convert to ctime accessor functions apparmor: convert to ctime accessor functions sunrpc: convert to ctime accessor functions ... 
Pull vfs timestamp updates from Christian Brauner:
 "This adds VFS support for multi-grain timestamps and converts tmpfs,
  xfs, ext4, and btrfs to use them. This carries acks from all relevant
  filesystems.

  The VFS always uses coarse-grained timestamps when updating the ctime
  and mtime after a change. This has the benefit of allowing filesystems
  to optimize away a lot of metadata updates, down to around 1 per
  jiffy, even when a file is under heavy writes.

  Unfortunately, this has always been an issue when we're exporting via
  NFSv3, which relies on timestamps to validate caches. A lot of changes
  can happen in a jiffy, so timestamps aren't sufficient to help the
  client decide to invalidate the cache.

  Even with NFSv4, a lot of exported filesystems don't properly support
  a change attribute and are subject to the same problems with timestamp
  granularity. Other applications have similar issues with timestamps
  (e.g., backup applications).

  If we were to always use fine-grained timestamps, that would improve
  the situation, but that becomes rather expensive, as the underlying
  filesystem would have to log a lot more metadata updates.

  This introduces fine-grained timestamps that are used when they are
  actively queried.

  This uses the 31st bit of the ctime tv_nsec field to indicate that
  something has queried the inode for the mtime or ctime. When this flag
  is set, on the next mtime or ctime update, the kernel will fetch a
  fine-grained timestamp instead of the usual coarse-grained one.

  As POSIX generally mandates that when the mtime changes, the ctime
  must also change the kernel always stores normalized ctime values, so
  only the first 30 bits of the tv_nsec field are ever used.

  Filesytems can opt into this behavior by setting the FS_MGTIME flag in
  the fstype. Filesystems that don't set this flag will continue to use
  coarse-grained timestamps.

  Various preparatory changes, fixes and cleanups are included:

   - Fixup all relevant places where POSIX requires updating ctime
     together with mtime. This is a wide-range of places and all
     maintainers provided necessary Acks.

   - Add new accessors for inode->i_ctime directly and change all
     callers to rely on them. Plain accesses to inode->i_ctime are now
     gone and it is accordingly rename to inode->__i_ctime and commented
     as requiring accessors.

   - Extend generic_fillattr() to pass in a request mask mirroring in a
     sense the statx() uapi. This allows callers to pass in a request
     mask to only get a subset of attributes filled in.

   - Rework timestamp updates so it's possible to drop the @now
     parameter the update_time() inode operation and associated helpers.

   - Add inode_update_timestamps() and convert all filesystems to it
     removing a bunch of open-coding"

* tag 'v6.6-vfs.ctime' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (107 commits)
  btrfs: convert to multigrain timestamps
  ext4: switch to multigrain timestamps
  xfs: switch to multigrain timestamps
  tmpfs: add support for multigrain timestamps
  fs: add infrastructure for multigrain timestamps
  fs: drop the timespec64 argument from update_time
  xfs: have xfs_vn_update_time gets its own timestamp
  fat: make fat_update_time get its own timestamp
  fat: remove i_version handling from fat_update_time
  ubifs: have ubifs_update_time use inode_update_timestamps
  btrfs: have it use inode_update_timestamps
  fs: drop the timespec64 arg from generic_update_time
  fs: pass the request_mask to generic_fillattr
  fs: remove silly warning from current_time
  gfs2: fix timestamp handling on quota inodes
  fs: rename i_ctime field to __i_ctime
  selinux: convert to ctime accessor functions
  security: convert to ctime accessor functions
  apparmor: convert to ctime accessor functions
  sunrpc: convert to ctime accessor functions
  ...
zonefs: fix synchronous direct writes to sequential files 2023-08-10T03:59:47+00:00 Damien Le Moal dlemoal@kernel.org 2023-08-07T04:11:48+00:00 fe9da61ffccad80ae79fadad836971acf0d465bd Commit 16d7fd3cfa72 ("zonefs: use iomap for synchronous direct writes") changes zonefs code from a self-built zone append BIO to using iomap for synchronous direct writes. This change relies on iomap submit BIO callback to change the write BIO built by iomap to a zone append BIO. However, this change overlooked the fact that a write BIO may be very large as it is split when issued. The change from a regular write to a zone append operation for the built BIO can result in a block layer warning as zone append BIO are not allowed to be split. WARNING: CPU: 18 PID: 202210 at block/bio.c:1644 bio_split+0x288/0x350 Call Trace: ? __warn+0xc9/0x2b0 ? bio_split+0x288/0x350 ? report_bug+0x2e6/0x390 ? handle_bug+0x41/0x80 ? exc_invalid_op+0x13/0x40 ? asm_exc_invalid_op+0x16/0x20 ? bio_split+0x288/0x350 bio_split_rw+0x4bc/0x810 ? __pfx_bio_split_rw+0x10/0x10 ? lockdep_unlock+0xf2/0x250 __bio_split_to_limits+0x1d8/0x900 blk_mq_submit_bio+0x1cf/0x18a0 ? __pfx_iov_iter_extract_pages+0x10/0x10 ? __pfx_blk_mq_submit_bio+0x10/0x10 ? find_held_lock+0x2d/0x110 ? lock_release+0x362/0x620 ? mark_held_locks+0x9e/0xe0 __submit_bio+0x1ea/0x290 ? __pfx___submit_bio+0x10/0x10 ? seqcount_lockdep_reader_access.constprop.0+0x82/0x90 submit_bio_noacct_nocheck+0x675/0xa20 ? __pfx_bio_iov_iter_get_pages+0x10/0x10 ? __pfx_submit_bio_noacct_nocheck+0x10/0x10 iomap_dio_bio_iter+0x624/0x1280 __iomap_dio_rw+0xa22/0x18a0 ? lock_is_held_type+0xe3/0x140 ? __pfx___iomap_dio_rw+0x10/0x10 ? lock_release+0x362/0x620 ? zonefs_file_write_iter+0x74c/0xc80 [zonefs] ? down_write+0x13d/0x1e0 iomap_dio_rw+0xe/0x40 zonefs_file_write_iter+0x5ea/0xc80 [zonefs] do_iter_readv_writev+0x18b/0x2c0 ? __pfx_do_iter_readv_writev+0x10/0x10 ? inode_security+0x54/0xf0 do_iter_write+0x13b/0x7c0 ? lock_is_held_type+0xe3/0x140 vfs_writev+0x185/0x550 ? __pfx_vfs_writev+0x10/0x10 ? __handle_mm_fault+0x9bd/0x1c90 ? find_held_lock+0x2d/0x110 ? lock_release+0x362/0x620 ? find_held_lock+0x2d/0x110 ? lock_release+0x362/0x620 ? __up_read+0x1ea/0x720 ? do_pwritev+0x136/0x1f0 do_pwritev+0x136/0x1f0 ? __pfx_do_pwritev+0x10/0x10 ? syscall_enter_from_user_mode+0x22/0x90 ? lockdep_hardirqs_on+0x7d/0x100 do_syscall_64+0x58/0x80 This error depends on the hardware used, specifically on the max zone append bytes and max_[hw_]sectors limits. Tests using AMD Epyc machines that have low limits did not reveal this issue while runs on Intel Xeon machines with larger limits trigger it. Manually splitting the zone append BIO using bio_split_rw() can solve this issue but also requires issuing the fragment BIOs synchronously with submit_bio_wait(), to avoid potential reordering of the zone append BIO fragments, which would lead to data corruption. That is, this solution is not better than using regular write BIOs which are subject to serialization using zone write locking at the IO scheduler level. Given this, fix the issue by removing zone append support and using regular write BIOs for synchronous direct writes. This allows preseving the use of iomap and having identical synchronous and asynchronous sequential file write path. Zone append support will be reintroduced later through io_uring commands to ensure that the needed special handling is done correctly. Reported-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com> Fixes: 16d7fd3cfa72 ("zonefs: use iomap for synchronous direct writes") Cc: stable@vger.kernel.org Signed-off-by: Damien Le Moal <dlemoal@kernel.org> Tested-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com> Reviewed-by: Christoph Hellwig <hch@lst.de> 
Commit 16d7fd3cfa72 ("zonefs: use iomap for synchronous direct writes")
changes zonefs code from a self-built zone append BIO to using iomap for
synchronous direct writes. This change relies on iomap submit BIO
callback to change the write BIO built by iomap to a zone append BIO.
However, this change overlooked the fact that a write BIO may be very
large as it is split when issued. The change from a regular write to a
zone append operation for the built BIO can result in a block layer
warning as zone append BIO are not allowed to be split.

WARNING: CPU: 18 PID: 202210 at block/bio.c:1644 bio_split+0x288/0x350
Call Trace:
? __warn+0xc9/0x2b0
? bio_split+0x288/0x350
? report_bug+0x2e6/0x390
? handle_bug+0x41/0x80
? exc_invalid_op+0x13/0x40
? asm_exc_invalid_op+0x16/0x20
? bio_split+0x288/0x350
bio_split_rw+0x4bc/0x810
? __pfx_bio_split_rw+0x10/0x10
? lockdep_unlock+0xf2/0x250
__bio_split_to_limits+0x1d8/0x900
blk_mq_submit_bio+0x1cf/0x18a0
? __pfx_iov_iter_extract_pages+0x10/0x10
? __pfx_blk_mq_submit_bio+0x10/0x10
? find_held_lock+0x2d/0x110
? lock_release+0x362/0x620
? mark_held_locks+0x9e/0xe0
__submit_bio+0x1ea/0x290
? __pfx___submit_bio+0x10/0x10
? seqcount_lockdep_reader_access.constprop.0+0x82/0x90
submit_bio_noacct_nocheck+0x675/0xa20
? __pfx_bio_iov_iter_get_pages+0x10/0x10
? __pfx_submit_bio_noacct_nocheck+0x10/0x10
iomap_dio_bio_iter+0x624/0x1280
__iomap_dio_rw+0xa22/0x18a0
? lock_is_held_type+0xe3/0x140
? __pfx___iomap_dio_rw+0x10/0x10
? lock_release+0x362/0x620
? zonefs_file_write_iter+0x74c/0xc80 [zonefs]
? down_write+0x13d/0x1e0
iomap_dio_rw+0xe/0x40
zonefs_file_write_iter+0x5ea/0xc80 [zonefs]
do_iter_readv_writev+0x18b/0x2c0
? __pfx_do_iter_readv_writev+0x10/0x10
? inode_security+0x54/0xf0
do_iter_write+0x13b/0x7c0
? lock_is_held_type+0xe3/0x140
vfs_writev+0x185/0x550
? __pfx_vfs_writev+0x10/0x10
? __handle_mm_fault+0x9bd/0x1c90
? find_held_lock+0x2d/0x110
? lock_release+0x362/0x620
? find_held_lock+0x2d/0x110
? lock_release+0x362/0x620
? __up_read+0x1ea/0x720
? do_pwritev+0x136/0x1f0
do_pwritev+0x136/0x1f0
? __pfx_do_pwritev+0x10/0x10
? syscall_enter_from_user_mode+0x22/0x90
? lockdep_hardirqs_on+0x7d/0x100
do_syscall_64+0x58/0x80

This error depends on the hardware used, specifically on the max zone
append bytes and max_[hw_]sectors limits. Tests using AMD Epyc machines
that have low limits did not reveal this issue while runs on Intel Xeon
machines with larger limits trigger it.

Manually splitting the zone append BIO using bio_split_rw() can solve
this issue but also requires issuing the fragment BIOs synchronously
with submit_bio_wait(), to avoid potential reordering of the zone append
BIO fragments, which would lead to data corruption. That is, this
solution is not better than using regular write BIOs which are subject
to serialization using zone write locking at the IO scheduler level.

Given this, fix the issue by removing zone append support and using
regular write BIOs for synchronous direct writes. This allows preseving
the use of iomap and having identical synchronous and asynchronous
sequential file write path. Zone append support will be reintroduced
later through io_uring commands to ensure that the needed special
handling is done correctly.

Reported-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Fixes: 16d7fd3cfa72 ("zonefs: use iomap for synchronous direct writes")
Cc: stable@vger.kernel.org
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Tested-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
iomap: Add per-block dirty state tracking to improve performance 2023-07-25T05:25:56+00:00 Ritesh Harjani (IBM) ritesh.list@gmail.com 2023-07-10T21:12:43+00:00 4ce02c67972211be488408c275c8fbf19faf29b3 When filesystem blocksize is less than folio size (either with mapping_large_folio_support() or with blocksize < pagesize) and when the folio is uptodate in pagecache, then even a byte write can cause an entire folio to be written to disk during writeback. This happens because we currently don't have a mechanism to track per-block dirty state within struct iomap_folio_state. We currently only track uptodate state. This patch implements support for tracking per-block dirty state in iomap_folio_state->state bitmap. This should help improve the filesystem write performance and help reduce write amplification. Performance testing of below fio workload reveals ~16x performance improvement using nvme with XFS (4k blocksize) on Power (64K pagesize) FIO reported write bw scores improved from around ~28 MBps to ~452 MBps. 1. <test_randwrite.fio> [global] ioengine=psync rw=randwrite overwrite=1 pre_read=1 direct=0 bs=4k size=1G dir=./ numjobs=8 fdatasync=1 runtime=60 iodepth=64 group_reporting=1 [fio-run] 2. Also our internal performance team reported that this patch improves their database workload performance by around ~83% (with XFS on Power) Reported-by: Aravinda Herle <araherle@in.ibm.com> Reported-by: Brian Foster <bfoster@redhat.com> Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com> Reviewed-by: Darrick J. Wong <djwong@kernel.org> 
When filesystem blocksize is less than folio size (either with
mapping_large_folio_support() or with blocksize < pagesize) and when the
folio is uptodate in pagecache, then even a byte write can cause
an entire folio to be written to disk during writeback. This happens
because we currently don't have a mechanism to track per-block dirty
state within struct iomap_folio_state. We currently only track uptodate
state.

This patch implements support for tracking per-block dirty state in
iomap_folio_state->state bitmap. This should help improve the filesystem
write performance and help reduce write amplification.

Performance testing of below fio workload reveals ~16x performance
improvement using nvme with XFS (4k blocksize) on Power (64K pagesize)
FIO reported write bw scores improved from around ~28 MBps to ~452 MBps.

1. <test_randwrite.fio>
[global]
	ioengine=psync
	rw=randwrite
	overwrite=1
	pre_read=1
	direct=0
	bs=4k
	size=1G
	dir=./
	numjobs=8
	fdatasync=1
	runtime=60
	iodepth=64
	group_reporting=1

[fio-run]

2. Also our internal performance team reported that this patch improves
   their database workload performance by around ~83% (with XFS on Power)

Reported-by: Aravinda Herle <araherle@in.ibm.com>
Reported-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
zonefs: convert to ctime accessor functions 2023-07-24T08:30:06+00:00 Jeff Layton jlayton@kernel.org 2023-07-05T19:01:48+00:00 f74207d84dab31ed7e36f530281c556c9815cbc5 In later patches, we're going to change how the inode's ctime field is used. Switch to using accessor functions instead of raw accesses of inode->i_ctime. Acked-by: Damien Le Moal <dlemoal@kernel.org> Signed-off-by: Jeff Layton <jlayton@kernel.org> Reviewed-by: Jan Kara <jack@suse.cz> Message-Id: <20230705190309.579783-81-jlayton@kernel.org> Signed-off-by: Christian Brauner <brauner@kernel.org> 
In later patches, we're going to change how the inode's ctime field is
used. Switch to using accessor functions instead of raw accesses of
inode->i_ctime.

Acked-by: Damien Le Moal <dlemoal@kernel.org>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Message-Id: <20230705190309.579783-81-jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>