[v3,00/21] block atomic writes for XFS

Message

John Garry April 29, 2024, 5:47 p.m. UTC

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 couple of patches are marked as RFC, as I am anything but 100% confident
in them. Indeed, from testing, there is an issue that I get ENOSPC at what
appears to be a moderate FS usage, like ~60%, and spaceman is reporting
appropriately-sized free extents. I notice that when I disable any
fallocate punch calls in my testing, then this issue goes away.  More
details available upon request.

Stripe alignment testing for forcealign changes should be noted at
https://lore.kernel.org/linux-xfs/[e-mail]/

Baseline is following series (which is based on v6.9-rc1):
https://lore.kernel.org/linux-block/[e-mail]/

Basic xfsprogs support at:
https://github.com/johnpgarry/xfsprogs-dev/tree/forcealign_and_atomicwrites_for_v3_xfs_block_atomic_writes

Patches for this series can be found at:
https://github.com/johnpgarry/linux/commits/atomic-writes-v6.9-v6-fs-v3/

Changes since v2:
https://lore.kernel.org/linux-xfs/[e-mail]/
- Incorporate forcealign patches from
  https://lore.kernel.org/linux-xfs/[e-mail]/
- 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

Changes since v1:
https://lore.kernel.org/linux-xfs/[e-mail]/
- Add blk_validate_atomic_write_op_size() (Darrick suggested idea)
- Swap forcealign for rtvol support (Dave requested forcealign)
- Sub-extent DIO zeroing (Dave wanted rid of XFS_BMAPI_ZERO usage)
- Improve coding for XFS statx support (Darrick, Ojaswin)
- Improve conditions for setting FMODE_CAN_ATOMIC_WRITE (Darrick)
- Improve commit message for FS_XFLAG_ATOMICWRITES flag (Darrick)
- Validate atomic writes in xfs_file_dio_write()
- Drop IOMAP_ATOMIC

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
  fs: xfs: align args->minlen for forced allocation alignment

John Garry (13):
  fs: Add generic_atomic_write_valid_size()
  xfs: Do not free EOF blocks for forcealign
  xfs: Update xfs_is_falloc_aligned() mask for forcealign
  xfs: Unmap blocks according to forcealign
  xfs: Only free full extents for forcealign
  iomap: Sub-extent zeroing
  fs: xfs: iomap: Sub-extent zeroing
  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

 fs/iomap/direct-io.c          |  27 ++-
 fs/xfs/libxfs/xfs_alloc.c     |  33 ++--
 fs/xfs/libxfs/xfs_alloc.h     |   3 +-
 fs/xfs/libxfs/xfs_bmap.c      | 302 ++++++++++++++++++----------------
 fs/xfs/libxfs/xfs_format.h    |  16 +-
 fs/xfs/libxfs/xfs_ialloc.c    |  12 +-
 fs/xfs/libxfs/xfs_inode_buf.c |  86 ++++++++++
 fs/xfs/libxfs/xfs_inode_buf.h |   3 +
 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_file.c             |  64 +++++--
 fs/xfs/xfs_inode.c            |  14 ++
 fs/xfs/xfs_inode.h            |  15 ++
 fs/xfs/xfs_ioctl.c            |  55 ++++++-
 fs/xfs/xfs_iomap.c            |  13 +-
 fs/xfs/xfs_iops.c             |  28 ++++
 fs/xfs/xfs_mount.h            |   4 +
 fs/xfs/xfs_super.c            |   8 +
 fs/xfs/xfs_trace.h            |   8 +-
 include/linux/fs.h            |  12 ++
 include/linux/iomap.h         |   1 +
 include/uapi/linux/fs.h       |   3 +
 24 files changed, 549 insertions(+), 195 deletions(-)