[PATCH v4 00/22] block atomic writes for xfs

Sat Jun 8 00:38:57 AEST 2024

This series expands atomic write support to filesystems, specifically
XFS. Extent alignment is based on new feature forcealign.

Flag FS_XFLAG_ATOMICWRITES is added as an enabling flag for atomic writes.

XFS can be formatted for atomic writes as follows:
mkfs.xfs -i forcealign=1 -d extsize=16384 -d atomic-writes=1  /dev/sda

atomic-writes=1 just enables atomic writes in the SB, but does not auto-
enable atomic writes for each file.

Support can be enabled through xfs_io command:
$xfs_io -c "lsattr -v" filename
[extsize, force-align]
$xfs_io -c "extsize" filename
[16384] filename
$xfs_io -c "chattr +W" filename
$xfs_io -c "lsattr -v" filename
[extsize, force-align, atomic-writes] filename
$xfs_io -c statx filename
...
stat.stx_atomic_write_unit_min = 4096
stat.stx_atomic_write_unit_max = 16384
stat.stx_atomic_write_segments_max = 1
...

A known issue - as reported in
https://urldefense.com/v3/__https://lore.kernel.org/linux-xfs/20240429174746.2132161-1-john.g.garry@oracle.com/T/*m7093bc85a8e0cbe13c111284768476d294aa077a__;Iw!!ACWV5N9M2RV99hQ!NbuQfXN8ZuUf_an3A6jHUXg3L1oCzefzyTYl0QWgJP1WbQCO8J_NPT9GHdGothSf36d0vxzJAjVUvcIB6IoU9nq3XExF$ 
-
is that forcealign is broken for !power-of-2 sizes. That needs fixing.

New in this series is a re-work of the iomap extent granularity zeroing
code. In the earlier series, iomap would consider a larger block zeroing
size when a member is set in struct iomap. Now each fs is responsible for
setting this size, which is i_blocksize(inode) when we just want regular
sub-fs block zeroing. All relevant FSes which use iomap are fixing up for
this.

Baseline is following series (which is based on Jens' block-6.10 branch):
https://lore.kernel.org/linux-nvme/96cb2069-a8e2-4723-802c-3ad4ba3e3d42@oracle.com/T/#mb980c084be402472601831c47fb2b66d0bfa8f0e

Basic xfsprogs support at:
https://github.com/johnpgarry/xfsprogs-dev/tree/forcealign_and_atomicwrites_for_v4_xfs_block_atomic_writes

Patches for this series can be found at:
https://github.com/johnpgarry/linux/commits/atomic-writes-v6.10-v7-fs-v4/

Changes since v3:
https://lore.kernel.org/linux-xfs/20240429174746.2132161-1-john.g.garry@oracle.com/T/#m9424b3cd1ccfde795d04474fdb4456520b6b4242
- Only enforce forcealign extsize is power-of-2 for atomic writes
- Re-org some validation code
- Fix xfs_bmap_process_allocated_extent() for forcealign
- Support iomap->io_block_size and make each fs support it
- Add !power-of-2 iomap support for io_block_size
- Make iomap dio iter handle atomic write failure properly by zeroing the
  remaining io_block_size

Changes since v2:
https://lore.kernel.org/linux-xfs/20240304130428.13026-1-john.g.garry@oracle.com/
- Incorporate forcealign patches from
  https://lore.kernel.org/linux-xfs/20240402233006.1210262-1-david@fromorbit.com/
- Put bdev awu min and max in buftarg
- Extra forcealign patches to deal with truncate and fallocate punch,
  insert, collapse
- Add generic_atomic_write_valid_size()
- Change iomap.extent_shift -> .extent_size

Darrick J. Wong (2):
  xfs: Introduce FORCEALIGN inode flag
  xfs: Enable file data forcealign feature

Dave Chinner (6):
  xfs: only allow minlen allocations when near ENOSPC
  xfs: always tail align maxlen allocations
  xfs: simplify extent allocation alignment
  xfs: make EOF allocation simpler
  xfs: introduce forced allocation alignment
  xfs: align args->minlen for forced allocation alignment

John Garry (14):
  fs: Add generic_atomic_write_valid_size()
  iomap: Allow filesystems set IO block zeroing size
  xfs: Use extent size granularity for iomap->io_block_size
  xfs: Do not free EOF blocks for forcealign
  xfs: Update xfs_inode_alloc_unitsize_fsb() for forcealign
  xfs: Unmap blocks according to forcealign
  xfs: Only free full extents for forcealign
  xfs: Don't revert allocated offset for forcealign
  fs: Add FS_XFLAG_ATOMICWRITES flag
  iomap: Atomic write support
  xfs: Support FS_XFLAG_ATOMICWRITES for forcealign
  xfs: Support atomic write for statx
  xfs: Validate atomic writes
  xfs: Support setting FMODE_CAN_ATOMIC_WRITE

 block/fops.c                  |   1 +
 fs/btrfs/inode.c              |   1 +
 fs/erofs/data.c               |   1 +
 fs/erofs/zmap.c               |   1 +
 fs/ext2/inode.c               |   1 +
 fs/ext4/extents.c             |   1 +
 fs/ext4/inode.c               |   1 +
 fs/f2fs/data.c                |   1 +
 fs/fuse/dax.c                 |   1 +
 fs/gfs2/bmap.c                |   1 +
 fs/hpfs/file.c                |   1 +
 fs/iomap/direct-io.c          |  41 ++++-
 fs/xfs/libxfs/xfs_alloc.c     |  33 ++--
 fs/xfs/libxfs/xfs_alloc.h     |   3 +-
 fs/xfs/libxfs/xfs_bmap.c      | 308 ++++++++++++++++++----------------
 fs/xfs/libxfs/xfs_format.h    |  16 +-
 fs/xfs/libxfs/xfs_ialloc.c    |  12 +-
 fs/xfs/libxfs/xfs_inode_buf.c | 105 ++++++++++++
 fs/xfs/libxfs/xfs_inode_buf.h |   5 +
 fs/xfs/libxfs/xfs_sb.c        |   4 +
 fs/xfs/xfs_bmap_util.c        |  14 +-
 fs/xfs/xfs_buf.c              |  15 +-
 fs/xfs/xfs_buf.h              |   4 +-
 fs/xfs/xfs_buf_mem.c          |   2 +-
 fs/xfs/xfs_file.c             |  49 +++++-
 fs/xfs/xfs_inode.c            |  41 ++++-
 fs/xfs/xfs_inode.h            |  29 ++++
 fs/xfs/xfs_ioctl.c            |  83 ++++++++-
 fs/xfs/xfs_iomap.c            |   7 +
 fs/xfs/xfs_iops.c             |  28 ++++
 fs/xfs/xfs_mount.h            |   4 +
 fs/xfs/xfs_reflink.h          |  10 --
 fs/xfs/xfs_super.c            |   8 +
 fs/xfs/xfs_trace.h            |   8 +-
 fs/zonefs/file.c              |   2 +
 include/linux/fs.h            |  12 ++
 include/linux/iomap.h         |   2 +
 include/uapi/linux/fs.h       |   3 +
 38 files changed, 656 insertions(+), 203 deletions(-)

-- 
2.31.1