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xfs: refine the unaligned check for always COW inodes in xfs_file_dio_write

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For always COW inodes we also must check the alignment of each individual
iovec segment, as they could end up with different I/Os due to the way
bio_iov_iter_get_pages works, and we'd then overwrite an already written
block.  The existing always_cow sysctl based code doesn't catch this
because nothing enforces that blocks aren't rewritten, but for zoned XFS
on sequential write required zones this is a hard error.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
This commit is contained in:
Christoph Hellwig 2023-10-27 09:58:24 +02:00
parent 8ae4c8cec0
commit 6fff175279
1 changed files with 10 additions and 1 deletions
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11
fs/xfs/xfs_file.c
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@ -721,7 +721,16 @@ xfs_file_dio_write(
/* direct I/O must be aligned to device logical sector size */
if ((iocb->ki_pos | count) & target->bt_logical_sectormask)
return -EINVAL;
if ((iocb->ki_pos | count) & ip->i_mount->m_blockmask)
/*
* For always COW inodes we also must check the alignment of each
* individual iovec segment, as they could end up with different
* I/Os due to the way bio_iov_iter_get_pages works, and we'd
* then overwrite an already written block.
*/
if (((iocb->ki_pos | count) & ip->i_mount->m_blockmask) ||
(xfs_is_always_cow_inode(ip) &&
(iov_iter_alignment(from) & ip->i_mount->m_blockmask)))
return xfs_file_dio_write_unaligned(ip, iocb, from);
return xfs_file_dio_write_aligned(ip, iocb, from);
}