xfs: make COW fork unwritten extent conversions more robust

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If we have racing buffered and direct I/O COW fork extents under
writeback can have been moved to the data fork by the time we call
xfs_reflink_convert_cow from xfs_submit_ioend.  This would be mostly
harmless as the block numbers don't change by this move, except for
the fact that xfs_bmapi_write will crash or trigger asserts when
not finding existing extents, even despite trying to paper over this
with the XFS_BMAPI_CONVERT_ONLY flag.

Instead of special casing non-transaction conversions in the already
way too complicated xfs_bmapi_write just add a new helper for the much
simpler non-transactional COW fork case, which simplify ignores not
found extents.

Signed-off-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>

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This commit is contained in:

Christoph Hellwig 2019-02-18 09:38:48 -08:00 • committed by Darrick J. Wong

parent db46e604ad

commit 26b91c728b

3 changed files with 45 additions and 33 deletions

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9

fs/xfs/libxfs/xfs_bmap.c

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8

fs/xfs/libxfs/xfs_bmap.h

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61

fs/xfs/xfs_reflink.c

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