[PATCH V3 07/10] xfs: Check for extent overflow when inserting a hole

[Chandan Babu R <chandanrlinux@gmail.com>]

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.

Signed-off-by: Chandan Babu R <chandanrlinux@gmail.com>
---
 fs/xfs/libxfs/xfs_inode_fork.h | 6 ++++++
 fs/xfs/xfs_bmap_util.c         | 9 +++++++++
 2 files changed, 15 insertions(+)

diff --git a/fs/xfs/libxfs/xfs_inode_fork.h b/fs/xfs/libxfs/xfs_inode_fork.h
index 83ff90e2a5fe..d0e49b015b62 100644
--- a/fs/xfs/libxfs/xfs_inode_fork.h
+++ b/fs/xfs/libxfs/xfs_inode_fork.h
@@ -73,6 +73,12 @@ struct xfs_ifork {
  * Hence extent count can increase by 2.
  */
 #define XFS_IEXT_WRITE_UNWRITTEN_CNT	(2)
+/*
+ * 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.
+ */
+#define XFS_IEXT_INSERT_HOLE_CNT	(1)
+
 
 /*
  * Fork handling.
diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
index 59d4da38aadf..e682eecebb1f 100644
--- a/fs/xfs/xfs_bmap_util.c
+++ b/fs/xfs/xfs_bmap_util.c
@@ -1165,6 +1165,15 @@ xfs_insert_file_space(
 	xfs_ilock(ip, XFS_ILOCK_EXCL);
 	xfs_trans_ijoin(tp, ip, 0);
 
+	/*
+	 * Splitting the extent mapping containing stop_fsb will cause
+	 * extent count to increase by 1.
+	 */
+	error = xfs_iext_count_may_overflow(ip, XFS_DATA_FORK,
+			XFS_IEXT_INSERT_HOLE_CNT);
+	if (error)
+		goto out_trans_cancel;
+
 	/*
 	 * The extent shifting code works on extent granularity. So, if stop_fsb
 	 * is not the starting block of extent, we need to split the extent at
-- 
2.28.0