diff mbox series

[V15,10/16] xfs: Check for extent overflow when remapping an extent

Message ID 20210126063232.3648053-11-chandanrlinux@gmail.com (mailing list archive)
State Accepted, archived
Headers show
Series Bail out if transaction can cause extent count to overflow | expand

Commit Message

Chandan Babu R Jan. 26, 2021, 6:32 a.m. UTC 
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>
---
 fs/xfs/xfs_reflink.c | 11 +++++++++++
 1 file changed, 11 insertions(+)
diff mbox series

Patch

diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index ca0ac1426d74..e1c98dbf79e4 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -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