[PATCH V9 09/14] xfs: Check for extent overflow when swapping extents

Chandan Babu R
2020-11-02T09:51:28Z

Removing an initial range of source/donor file's extent and adding a new
extent (from donor/source file) in its place will cause extent count to
increase by 1.

Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
Signed-off-by: Chandan Babu R <chandanrlinux@gmail.com>
---
fs/xfs/libxfs/xfs_inode_fork.h | 7 +++++++
fs/xfs/xfs_bmap_util.c | 16 ++++++++++++++++
2 files changed, 23 insertions(+)

diff --git a/fs/xfs/libxfs/xfs_inode_fork.h b/fs/xfs/libxfs/xfs_inode_fork.h
index b99e67e7b59b..969b06160d44 100644
--- a/fs/xfs/libxfs/xfs_inode_fork.h
+++ b/fs/xfs/libxfs/xfs_inode_fork.h
@@ -87,6 +87,13 @@ struct xfs_ifork {
*/
#define XFS_IEXT_REFLINK_END_COW_CNT (2)

+/*
+ * Removing an initial range of source/donor file's extent and adding a new
+ * extent (from donor/source file) in its place will cause extent count to
+ * increase by 1.
+ */
+#define XFS_IEXT_SWAP_RMAP_CNT (1)
+
/*
* Fork handling.
*/
diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
index 0776abd0103c..b6728fdf50ae 100644
--- a/fs/xfs/xfs_bmap_util.c
+++ b/fs/xfs/xfs_bmap_util.c
@@ -1407,6 +1407,22 @@ xfs_swap_extent_rmap(
irec.br_blockcount);
trace_xfs_swap_extent_rmap_remap_piece(tip, &uirec);

+ if (xfs_bmap_is_real_extent(&uirec)) {
+ error = xfs_iext_count_may_overflow(ip,
+ XFS_DATA_FORK,
+ XFS_IEXT_SWAP_RMAP_CNT);
+ if (error)
+ goto out;
+ }
+
+ if (xfs_bmap_is_real_extent(&irec)) {
+ error = xfs_iext_count_may_overflow(tip,
+ XFS_DATA_FORK,
+ XFS_IEXT_SWAP_RMAP_CNT);
+ if (error)
+ goto out;
+ }
+
/* Remove the mapping from the donor file. */
xfs_bmap_unmap_extent(tp, tip, &uirec);

--
2.28.0