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authorBrian Foster <bfoster@redhat.com>2017-02-16 17:19:12 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-02-26 11:10:52 +0100
commitd004006055974a976841c4f95e8c25ca7b5b38d5 (patch)
parent57d759622aa76591958f46707edebe20c284b7d2 (diff)
xfs: clear delalloc and cache on buffered write failure
commit fa7f138ac4c70dc00519c124cf7cd4862a0a5b0e upstream. The buffered write failure handling code in xfs_file_iomap_end_delalloc() has a couple minor problems. First, if written == 0, start_fsb is not rounded down and it fails to kill off a delalloc block if the start offset is block unaligned. This results in a lingering delalloc block and broken delalloc block accounting detected at unmount time. Fix this by rounding down start_fsb in the unlikely event that written == 0. Second, it is possible for a failed overwrite of a delalloc extent to leave dirty pagecache around over a hole in the file. This is because is possible to hit ->iomap_end() on write failure before the iomap code has attempted to allocate pagecache, and thus has no need to clean it up. If the targeted delalloc extent was successfully written by a previous write, however, then it does still have dirty pages when ->iomap_end() punches out the underlying blocks. This ultimately results in writeback over a hole. To fix this problem, unconditionally punch out the pagecache from XFS before the associated delalloc range. Signed-off-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 files changed, 12 insertions, 1 deletions
diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index cdc6bdd495be..e8889614cec3 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -1068,7 +1068,15 @@ xfs_file_iomap_end_delalloc(
xfs_fileoff_t end_fsb;
int error = 0;
- start_fsb = XFS_B_TO_FSB(mp, offset + written);
+ /*
+ * start_fsb refers to the first unused block after a short write. If
+ * nothing was written, round offset down to point at the first block in
+ * the range.
+ */
+ if (unlikely(!written))
+ start_fsb = XFS_B_TO_FSBT(mp, offset);
+ else
+ start_fsb = XFS_B_TO_FSB(mp, offset + written);
end_fsb = XFS_B_TO_FSB(mp, offset + length);
@@ -1080,6 +1088,9 @@ xfs_file_iomap_end_delalloc(
* blocks in the range, they are ours.
if (start_fsb < end_fsb) {
+ truncate_pagecache_range(VFS_I(ip), XFS_FSB_TO_B(mp, start_fsb),
+ XFS_FSB_TO_B(mp, end_fsb) - 1);
xfs_ilock(ip, XFS_ILOCK_EXCL);
error = xfs_bmap_punch_delalloc_range(ip, start_fsb,
end_fsb - start_fsb);