[PATCH 2/7] xfs: Check for per-inode extent count overflow

Chandan Babu R
2020-06-06T08:28:17Z

The following error message was noticed when a workload added one
million xattrs, deleted 50% of them and then inserted 400,000 new
xattrs.

XFS (loop0): xfs_iflush_int: detected corrupt incore inode 131, total extents = -19916, nblocks = 102937, ptr ffff9ce33b098c00

The error message was printed during unmounting the filesystem. The
value printed under "total extents" indicates that we overflowed the
per-inode signed 16-bit xattr extent counter.

Instead of letting this silent corruption occur, this patch checks for
extent counter (both data and xattr) overflow before we assign the
new value to the corresponding in-memory extent counter.

Signed-off-by: Chandan Babu R <chandanrlinux@gmail.com>
---
fs/xfs/libxfs/xfs_bmap.c | 92 +++++++++++++++++++++++++++-------
fs/xfs/libxfs/xfs_inode_fork.c | 29 +++++++++++
fs/xfs/libxfs/xfs_inode_fork.h | 1 +
3 files changed, 104 insertions(+), 18 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index edc63dba007f..798fca5c52af 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -906,7 +906,10 @@ xfs_bmap_local_to_extents(
xfs_iext_first(ifp, &icur);
xfs_iext_insert(ip, &icur, &rec, 0);

- ifp->if_nextents = 1;
+ error = xfs_next_set(ip, whichfork, 1);
+ if (error)
+ goto done;
+
ip->i_d.di_nblocks = 1;
xfs_trans_mod_dquot_byino(tp, ip,
XFS_TRANS_DQ_BCOUNT, 1L);
@@ -1594,7 +1597,10 @@ xfs_bmap_add_extent_delay_real(
xfs_iext_remove(bma->ip, &bma->icur, state);
xfs_iext_prev(ifp, &bma->icur);
xfs_iext_update_extent(bma->ip, state, &bma->icur, &LEFT);
- ifp->if_nextents--;
+
+ error = xfs_next_set(bma->ip, whichfork, -1);
+ if (error)
+ goto done;

if (bma->cur == NULL)
rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
@@ -1698,7 +1704,10 @@ xfs_bmap_add_extent_delay_real(
PREV.br_startblock = new->br_startblock;
PREV.br_state = new->br_state;
xfs_iext_update_extent(bma->ip, state, &bma->icur, &PREV);
- ifp->if_nextents++;
+
+ error = xfs_next_set(bma->ip, whichfork, 1);
+ if (error)
+ goto done;

if (bma->cur == NULL)
rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
@@ -1764,7 +1773,10 @@ xfs_bmap_add_extent_delay_real(
* The left neighbor is not contiguous.
*/
xfs_iext_update_extent(bma->ip, state, &bma->icur, new);
- ifp->if_nextents++;
+
+ error = xfs_next_set(bma->ip, whichfork, 1);
+ if (error)
+ goto done;

if (bma->cur == NULL)
rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
@@ -1851,7 +1863,10 @@ xfs_bmap_add_extent_delay_real(
* The right neighbor is not contiguous.
*/
xfs_iext_update_extent(bma->ip, state, &bma->icur, new);
- ifp->if_nextents++;
+
+ error = xfs_next_set(bma->ip, whichfork, 1);
+ if (error)
+ goto done;

if (bma->cur == NULL)
rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
@@ -1937,7 +1952,10 @@ xfs_bmap_add_extent_delay_real(
xfs_iext_next(ifp, &bma->icur);
xfs_iext_insert(bma->ip, &bma->icur, &RIGHT, state);
xfs_iext_insert(bma->ip, &bma->icur, &LEFT, state);
- ifp->if_nextents++;
+
+ error = xfs_next_set(bma->ip, whichfork, 1);
+ if (error)
+ goto done;

if (bma->cur == NULL)
rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
@@ -2141,7 +2159,11 @@ xfs_bmap_add_extent_unwritten_real(
xfs_iext_remove(ip, icur, state);
xfs_iext_prev(ifp, icur);
xfs_iext_update_extent(ip, state, icur, &LEFT);
- ifp->if_nextents -= 2;
+
+ error = xfs_next_set(ip, whichfork, -2);
+ if (error)
+ goto done;
+
if (cur == NULL)
rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
else {
@@ -2193,7 +2215,11 @@ xfs_bmap_add_extent_unwritten_real(
xfs_iext_remove(ip, icur, state);
xfs_iext_prev(ifp, icur);
xfs_iext_update_extent(ip, state, icur, &LEFT);
- ifp->if_nextents--;
+
+ error = xfs_next_set(ip, whichfork, -1);
+ if (error)
+ goto done;
+
if (cur == NULL)
rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
else {
@@ -2235,7 +2261,10 @@ xfs_bmap_add_extent_unwritten_real(
xfs_iext_remove(ip, icur, state);
xfs_iext_prev(ifp, icur);
xfs_iext_update_extent(ip, state, icur, &PREV);
- ifp->if_nextents--;
+
+ error = xfs_next_set(ip, whichfork, -1);
+ if (error)
+ goto done;

if (cur == NULL)
rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
@@ -2343,7 +2372,10 @@ xfs_bmap_add_extent_unwritten_real(

xfs_iext_update_extent(ip, state, icur, &PREV);
xfs_iext_insert(ip, icur, new, state);
- ifp->if_nextents++;
+
+ error = xfs_next_set(ip, whichfork, 1);
+ if (error)
+ goto done;

if (cur == NULL)
rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
@@ -2419,7 +2451,10 @@ xfs_bmap_add_extent_unwritten_real(
xfs_iext_update_extent(ip, state, icur, &PREV);
xfs_iext_next(ifp, icur);
xfs_iext_insert(ip, icur, new, state);
- ifp->if_nextents++;
+
+ error = xfs_next_set(ip, whichfork, 1);
+ if (error)
+ goto done;

if (cur == NULL)
rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
@@ -2471,7 +2506,10 @@ xfs_bmap_add_extent_unwritten_real(
xfs_iext_next(ifp, icur);
xfs_iext_insert(ip, icur, &r[1], state);
xfs_iext_insert(ip, icur, &r[0], state);
- ifp->if_nextents += 2;
+
+ error = xfs_next_set(ip, whichfork, 2);
+ if (error)
+ goto done;

if (cur == NULL)
rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
@@ -2787,7 +2825,10 @@ xfs_bmap_add_extent_hole_real(
xfs_iext_remove(ip, icur, state);
xfs_iext_prev(ifp, icur);
xfs_iext_update_extent(ip, state, icur, &left);
- ifp->if_nextents--;
+
+ error = xfs_next_set(ip, whichfork, -1);
+ if (error)
+ goto done;

if (cur == NULL) {
rval = XFS_ILOG_CORE | xfs_ilog_fext(whichfork);
@@ -2886,7 +2927,10 @@ xfs_bmap_add_extent_hole_real(
* Insert a new entry.
*/
xfs_iext_insert(ip, icur, new, state);
- ifp->if_nextents++;
+
+ error = xfs_next_set(ip, whichfork, 1);
+ if (error)
+ goto done;

if (cur == NULL) {
rval = XFS_ILOG_CORE | xfs_ilog_fext(whichfork);
@@ -5083,7 +5127,10 @@ xfs_bmap_del_extent_real(
*/
xfs_iext_remove(ip, icur, state);
xfs_iext_prev(ifp, icur);
- ifp->if_nextents--;
+
+ error = xfs_next_set(ip, whichfork, -1);
+ if (error)
+ goto done;

flags |= XFS_ILOG_CORE;
if (!cur) {
@@ -5193,7 +5240,10 @@ xfs_bmap_del_extent_real(
} else
flags |= xfs_ilog_fext(whichfork);

- ifp->if_nextents++;
+ error = xfs_next_set(ip, whichfork, 1);
+ if (error)
+ goto done;
+
xfs_iext_next(ifp, icur);
xfs_iext_insert(ip, icur, &new, state);
break;
@@ -5660,7 +5710,10 @@ xfs_bmse_merge(
* Update the on-disk extent count, the btree if necessary and log the
* inode.
*/
- ifp->if_nextents--;
+ error = xfs_next_set(ip, whichfork, -1);
+ if (error)
+ goto done;
+
*logflags |= XFS_ILOG_CORE;
if (!cur) {
*logflags |= XFS_ILOG_DEXT;
@@ -6047,7 +6100,10 @@ xfs_bmap_split_extent(
/* Add new extent */
xfs_iext_next(ifp, &icur);
xfs_iext_insert(ip, &icur, &new, 0);
- ifp->if_nextents++;
+
+ error = xfs_next_set(ip, whichfork, 1);
+ if (error)
+ goto del_cursor;

if (cur) {
error = xfs_bmbt_lookup_eq(cur, &new, &i);
diff --git a/fs/xfs/libxfs/xfs_inode_fork.c b/fs/xfs/libxfs/xfs_inode_fork.c
index 28b366275ae0..3bf5a2c391bd 100644
--- a/fs/xfs/libxfs/xfs_inode_fork.c
+++ b/fs/xfs/libxfs/xfs_inode_fork.c
@@ -728,3 +728,32 @@ xfs_ifork_verify_local_attr(

return 0;
}
+
+int
+xfs_next_set(
+ struct xfs_inode *ip,
+ int whichfork,
+ int delta)
+{
+ struct xfs_ifork *ifp;
+ int64_t nr_exts;
+ int64_t max_exts;
+
+ ifp = XFS_IFORK_PTR(ip, whichfork);
+
+ if (whichfork == XFS_DATA_FORK || whichfork == XFS_COW_FORK)
+ max_exts = MAXEXTNUM;
+ else if (whichfork == XFS_ATTR_FORK)
+ max_exts = MAXAEXTNUM;
+ else
+ ASSERT(0);
+
+ nr_exts = ifp->if_nextents + delta;
+ if ((delta > 0 && nr_exts > max_exts)
+ || (delta < 0 && nr_exts < 0))
+ return -EOVERFLOW;
+
+ ifp->if_nextents = nr_exts;
+
+ return 0;
+}
diff --git a/fs/xfs/libxfs/xfs_inode_fork.h b/fs/xfs/libxfs/xfs_inode_fork.h
index a4953e95c4f3..a84ae42ace79 100644
--- a/fs/xfs/libxfs/xfs_inode_fork.h
+++ b/fs/xfs/libxfs/xfs_inode_fork.h
@@ -173,4 +173,5 @@ extern void xfs_ifork_init_cow(struct xfs_inode *ip);
int xfs_ifork_verify_local_data(struct xfs_inode *ip);
int xfs_ifork_verify_local_attr(struct xfs_inode *ip);

+int xfs_next_set(struct xfs_inode *ip, int whichfork, int delta);
#endif /* __XFS_INODE_FORK_H__ */
--
2.20.1