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xfs: Check for extent overflow when remapping an extent 

Remapping an extent involves unmapping the existing extent and mapping
in the new extent. When unmapping, an extent containing the entire unmap
range can be split into two extents,
i.e. | Old extent | hole | Old extent |
Hence extent count increases by 1.

Mapping in the new extent into the destination file can increase the
extent count by 1.

Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
Reviewed-by: Darrick J. Wong <darrick.wong@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 5f1d5bbfb2
commit ee898d78c3
1 changed files with 11 additions and 0 deletions
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11
fs/xfs/xfs_reflink.c
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@ -1006,6 +1006,7 @@ xfs_reflink_remap_extent(
unsigned int resblks;
bool smap_real;
bool dmap_written = xfs_bmap_is_written_extent(dmap);
int iext_delta = 0;
int nimaps;
int error;
@ -1099,6 +1100,16 @@ xfs_reflink_remap_extent(
goto out_cancel;
}
if (smap_real)
++iext_delta;
if (dmap_written)
++iext_delta;
error = xfs_iext_count_may_overflow(ip, XFS_DATA_FORK, iext_delta);
if (error)
goto out_cancel;
if (smap_real) {
/*
* If the extent we're unmapping is backed by storage (written