[PATCH V4 03/10] xfs: Check for extent overflow when punching a hole

Chandan Babu R
2020-09-18T09:48:27Z

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 | 7 +++++++
fs/xfs/xfs_bmap_item.c | 5 +++++
fs/xfs/xfs_bmap_util.c | 10 ++++++++++
3 files changed, 22 insertions(+)

diff --git a/fs/xfs/libxfs/xfs_inode_fork.h b/fs/xfs/libxfs/xfs_inode_fork.h
index 7fc2b129a2e7..bcac769a7df6 100644
--- a/fs/xfs/libxfs/xfs_inode_fork.h
+++ b/fs/xfs/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.
*/
diff --git a/fs/xfs/xfs_bmap_item.c b/fs/xfs/xfs_bmap_item.c
index ec3691372e7c..5c7d08da8ff1 100644
--- a/fs/xfs/xfs_bmap_item.c
+++ b/fs/xfs/xfs_bmap_item.c
@@ -519,6 +519,11 @@ xfs_bui_item_recover(
}
xfs_trans_ijoin(tp, ip, 0);

+ error = xfs_iext_count_may_overflow(ip, whichfork,
+ XFS_IEXT_PUNCH_HOLE_CNT);
+ if (error)
+ goto err_inode;
+
count = bmap->me_len;
error = xfs_trans_log_finish_bmap_update(tp, budp, type, ip, whichfork,
bmap->me_startoff, bmap->me_startblock, &count, state);
diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
index dcd6e61df711..0776abd0103c 100644
--- a/fs/xfs/xfs_bmap_util.c
+++ b/fs/xfs/xfs_bmap_util.c
@@ -891,6 +891,11 @@ xfs_unmap_extent(

xfs_trans_ijoin(tp, ip, 0);

+ error = xfs_iext_count_may_overflow(ip, XFS_DATA_FORK,
+ XFS_IEXT_PUNCH_HOLE_CNT);
+ if (error)
+ goto out_trans_cancel;
+
error = xfs_bunmapi(tp, ip, startoffset_fsb, len_fsb, 0, 2, done);
if (error)
goto out_trans_cancel;
@@ -1176,6 +1181,11 @@ xfs_insert_file_space(
xfs_ilock(ip, XFS_ILOCK_EXCL);
xfs_trans_ijoin(tp, ip, 0);

+ error = xfs_iext_count_may_overflow(ip, XFS_DATA_FORK,
+ XFS_IEXT_PUNCH_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