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xfs: Check for extent overflow when moving extent from cow to data fork

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Moving an extent to data fork can cause a sub-interval of an existing
extent to be unmapped. This will increase extent count by 1. Mapping in
the new extent can increase the extent count by 1 again i.e.
 | Old extent | New extent | Old extent |
Hence number of extents increases by 2.

Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
Signed-off-by: Chandan Babu R <chandanrlinux@gmail.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
This commit is contained in:
Chandan Babu R 2021-01-22 16:48:14 -08:00 committed by Darrick J. Wong
parent c442f3086d
commit 5f1d5bbfb2
2 changed files with 14 additions and 0 deletions
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9
fs/xfs/libxfs/xfs_inode_fork.h
View File

@ -79,6 +79,15 @@ struct xfs_ifork {
#define XFS_IEXT_WRITE_UNWRITTEN_CNT (2)
/*
* Moving an extent to data fork can cause a sub-interval of an existing extent
* to be unmapped. This will increase extent count by 1. Mapping in the new
* extent can increase the extent count by 1 again i.e.
* | Old extent | New extent | Old extent |
* Hence number of extents increases by 2.
*/
#define XFS_IEXT_REFLINK_END_COW_CNT (2)
/*
* Fork handling.
*/

5
fs/xfs/xfs_reflink.c
View File

@ -628,6 +628,11 @@ xfs_reflink_end_cow_extent(
xfs_ilock(ip, XFS_ILOCK_EXCL);
xfs_trans_ijoin(tp, ip, 0);
error = xfs_iext_count_may_overflow(ip, XFS_DATA_FORK,
XFS_IEXT_REFLINK_END_COW_CNT);
if (error)
goto out_cancel;
/*
* In case of racing, overlapping AIO writes no COW extents might be
* left by the time I/O completes for the loser of the race. In that