[PATCH V4 09/10] xfs: Check for extent overflow when swapping extents

Chandan Babu R
2020-09-18T09:48:45Z

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.

Signed-off-by: Chandan Babu R <chandanrlinux@gmail.com>
---
fs/xfs/libxfs/xfs_bmap.c | 18 +++++++++---------
fs/xfs/libxfs/xfs_bmap.h | 1 +
fs/xfs/libxfs/xfs_inode_fork.h | 7 +++++++
fs/xfs/xfs_bmap_util.c | 17 +++++++++++++++++
4 files changed, 34 insertions(+), 9 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index 51c2d2690f05..9c665e379dfc 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -6104,15 +6104,6 @@ xfs_bmap_split_extent(
return error;
}

-/* Deferred mapping is only for real extents in the data fork. */
-static bool
-xfs_bmap_is_update_needed(
- struct xfs_bmbt_irec *bmap)
-{
- return bmap->br_startblock != HOLESTARTBLOCK &&
- bmap->br_startblock != DELAYSTARTBLOCK;
-}
-
/* Record a bmap intent. */
static int
__xfs_bmap_add(
@@ -6144,6 +6135,15 @@ __xfs_bmap_add(
return 0;
}

+/* Deferred mapping is only for real extents in the data fork. */
+bool
+xfs_bmap_is_update_needed(
+ struct xfs_bmbt_irec *bmap)
+{
+ return bmap->br_startblock != HOLESTARTBLOCK &&
+ bmap->br_startblock != DELAYSTARTBLOCK;
+}
+
/* Map an extent into a file. */
void
xfs_bmap_map_extent(
diff --git a/fs/xfs/libxfs/xfs_bmap.h b/fs/xfs/libxfs/xfs_bmap.h
index e1bd484e5548..60fbe184d5f4 100644
--- a/fs/xfs/libxfs/xfs_bmap.h
+++ b/fs/xfs/libxfs/xfs_bmap.h
@@ -263,6 +263,7 @@ struct xfs_bmap_intent {
struct xfs_bmbt_irec bi_bmap;
};

+bool xfs_bmap_is_update_needed(struct xfs_bmbt_irec *bmap);
int xfs_bmap_finish_one(struct xfs_trans *tp, struct xfs_inode *ip,
enum xfs_bmap_intent_type type, int whichfork,
xfs_fileoff_t startoff, xfs_fsblock_t startblock,
diff --git a/fs/xfs/libxfs/xfs_inode_fork.h b/fs/xfs/libxfs/xfs_inode_fork.h
index ded3c1b56c94..837c01595439 100644
--- a/fs/xfs/libxfs/xfs_inode_fork.h
+++ b/fs/xfs/libxfs/xfs_inode_fork.h
@@ -102,6 +102,13 @@ struct xfs_ifork {
#define XFS_IEXT_REFLINK_REMAP_CNT(smap_real, dmap_written) \
(((smap_real) ? 1 : 0) + ((dmap_written) ? 1 : 0))

+/*
+ * 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..542f990247c4 100644
--- a/fs/xfs/xfs_bmap_util.c
+++ b/fs/xfs/xfs_bmap_util.c
@@ -28,6 +28,7 @@
#include "xfs_icache.h"
#include "xfs_iomap.h"
#include "xfs_reflink.h"
+#include "xfs_bmap.h"

/* Kernel only BMAP related definitions and functions */

@@ -1407,6 +1408,22 @@ xfs_swap_extent_rmap(
irec.br_blockcount);
trace_xfs_swap_extent_rmap_remap_piece(tip, &uirec);

+ if (xfs_bmap_is_update_needed(&uirec)) {
+ error = xfs_iext_count_may_overflow(ip,
+ XFS_DATA_FORK,
+ XFS_IEXT_SWAP_RMAP_CNT);
+ if (error)
+ goto out;
+ }
+
+ if (xfs_bmap_is_update_needed(&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