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xfs: reclaim speculative preallocations for append only files

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The XFS XFS_DIFLAG_APPEND maps to the VFS S_APPEND flag, which forbids
writes that don't append at the current EOF.

But the commit originally adding XFS_DIFLAG_APPEND support (commit
a23321e766d in xfs xfs-import repository) also checked it to skip
releasing speculative preallocations, which doesn't make any sense.

Another commit (dd9f438e32 in the xfs-import repository) later extended
that flag to also report these speculation preallocations which should
not exist in getbmap.

Remove these checks as nothing XFS_DIFLAG_APPEND implies that
preallocations beyond EOF should exist, but explicitly check for
XFS_DIFLAG_APPEND in xfs_file_release to bypass the algorithm that
discard preallocations on the first close as append only files aren't
expected to be written to only once.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>
This commit is contained in:
Christoph Hellwig 2024-08-13 09:39:42 +02:00 committed by Chandan Babu R
parent 11f4c3a53a
commit 9372dce08b
3 changed files with 10 additions and 8 deletions
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12
fs/xfs/xfs_bmap_util.c
View File

@ -331,8 +331,7 @@ xfs_getbmap(
} }
if (xfs_get_extsz_hint(ip) || if (xfs_get_extsz_hint(ip) ||
(ip->i_diflags & (ip->i_diflags & XFS_DIFLAG_PREALLOC))
(XFS_DIFLAG_PREALLOC | XFS_DIFLAG_APPEND)))
max_len = mp->m_super->s_maxbytes; max_len = mp->m_super->s_maxbytes;
else else
max_len = XFS_ISIZE(ip); max_len = XFS_ISIZE(ip);
@ -524,12 +523,11 @@ xfs_can_free_eofblocks(
return false; return false;
/* /*
* Only free real extents for inodes with persistent preallocations or * Do not free real extents in preallocated files unless the file has
* the append-only flag. * delalloc blocks and we are forced to remove them.
*/ */
if (ip->i_diflags & (XFS_DIFLAG_PREALLOC | XFS_DIFLAG_APPEND)) if ((ip->i_diflags & XFS_DIFLAG_PREALLOC) && !ip->i_delayed_blks)
if (ip->i_delayed_blks == 0) return false;
return false;
/* /*
* Do not try to free post-EOF blocks if EOF is beyond the end of the * Do not try to free post-EOF blocks if EOF is beyond the end of the

4
fs/xfs/xfs_file.c
View File

@ -1220,6 +1220,9 @@ xfs_file_release(
* one file after another without going back to it while keeping the * one file after another without going back to it while keeping the
* preallocation for files that have recurring open/write/close cycles. * preallocation for files that have recurring open/write/close cycles.
* *
* This heuristic is skipped for inodes with the append-only flag as
* that flag is rather pointless for inodes written only once.
*
* There is no point in freeing blocks here for open but unlinked files * There is no point in freeing blocks here for open but unlinked files
* as they will be taken care of by the inactivation path soon. * as they will be taken care of by the inactivation path soon.
* *
@ -1234,6 +1237,7 @@ xfs_file_release(
*/ */
if (inode->i_nlink && if (inode->i_nlink &&
(file->f_mode & FMODE_WRITE) && (file->f_mode & FMODE_WRITE) &&
!(ip->i_diflags & XFS_DIFLAG_APPEND) &&
!xfs_iflags_test(ip, XFS_EOFBLOCKS_RELEASED) && !xfs_iflags_test(ip, XFS_EOFBLOCKS_RELEASED) &&
xfs_ilock_nowait(ip, XFS_IOLOCK_EXCL)) { xfs_ilock_nowait(ip, XFS_IOLOCK_EXCL)) {
if (xfs_can_free_eofblocks(ip) && if (xfs_can_free_eofblocks(ip) &&

2
fs/xfs/xfs_icache.c
View File

@ -1159,7 +1159,7 @@ xfs_inode_free_eofblocks(
if (xfs_can_free_eofblocks(ip)) if (xfs_can_free_eofblocks(ip))
return xfs_free_eofblocks(ip); return xfs_free_eofblocks(ip);
/* inode could be preallocated or append-only */ /* inode could be preallocated */
trace_xfs_inode_free_eofblocks_invalid(ip); trace_xfs_inode_free_eofblocks_invalid(ip);
xfs_inode_clear_eofblocks_tag(ip); xfs_inode_clear_eofblocks_tag(ip);
return 0; return 0;