Commit ee898d78 authored by Chandan Babu R's avatar Chandan Babu R Committed by Darrick J. Wong
Browse files

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: default avatarAllison Henderson <allison.henderson@oracle.com>
Reviewed-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: default avatarChandan Babu R <chandanrlinux@gmail.com>
Signed-off-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
parent 5f1d5bbf

fs/xfs/xfs_reflink.c

+11 −0
Original line number Diff line number Diff line
@@ -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