xfs: commit CoW-based atomic writes atomically

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When completing a CoW-based write, each extent range mapping update is
covered by a separate transaction.

For a CoW-based atomic write, all mappings must be changed at once, so
change to use a single transaction.

Note that there is a limit on the amount of log intent items which can be
fit into a single transaction, but this is being ignored for now since
the count of items for a typical atomic write would be much less than is
typically supported. A typical atomic write would be expected to be 64KB
or less, which means only 16 possible extents unmaps, which is quite
small.

Reviewed-by: Darrick J. Wong <djwong@kernel.org>
[djwong: add tr_atomic_ioend]
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: John Garry <john.g.garry@oracle.com>

...

This commit is contained in:

John Garry 2025-05-07 14:18:31 -07:00 • committed by Darrick J. Wong

parent 11ab31909d

commit b1e09178b7

6 changed files with 82 additions and 1 deletions

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4

fs/xfs/libxfs/xfs_log_rlimit.c

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fs/xfs/libxfs/xfs_trans_resv.c

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fs/xfs/libxfs/xfs_trans_resv.h

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fs/xfs/xfs_file.c

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fs/xfs/xfs_reflink.c

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fs/xfs/xfs_reflink.h

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