xfs: Check for extent overflow when punching a hole

Source kernel commit: 85ef08b5a667615bc7be5058259753dc42a7adcd

The extent mapping the file offset at which a hole has to be
inserted will be split into two extents causing extent count to
increase by 1.

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>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>

diff --git a/libxfs/xfs_inode_fork.h b/libxfs/xfs_inode_fork.h
index 7fc2b129a2e79ff998acc4c0ced441cf8d18e205..bcac769a7df6fddf9baca65f294cbfb2388c448c 100644 (file)
--- a/libxfs/xfs_inode_fork.h
+++ b/libxfs/xfs_inode_fork.h
@@ -40,6 +40,13 @@ struct xfs_ifork {
  */
 #define XFS_IEXT_ADD_NOSPLIT_CNT       (1)
 
+/*
+ * Punching out an extent from the middle of an existing extent can cause the
+ * extent count to increase by 1.
+ * i.e. | Old extent | Hole | Old extent |
+ */
+#define XFS_IEXT_PUNCH_HOLE_CNT                (1)
+
 /*
  * Fork handling.
  */