[PATCH V4 04/10] xfs: Check for extent overflow when adding/removing xattrs

Chandan Babu R
2020-09-18T09:48:30Z

Adding/removing an xattr can cause XFS_DA_NODE_MAXDEPTH extents to be
added. One extra extent for dabtree in case a local attr is large enough
to cause a double split. It can also cause extent count to increase
proportional to the size of a remote xattr's value.

Signed-off-by: Chandan Babu R <chandanrlinux@gmail.com>
---
fs/xfs/libxfs/xfs_attr.c | 13 +++++++++++++
fs/xfs/libxfs/xfs_inode_fork.h | 10 ++++++++++
2 files changed, 23 insertions(+)

diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
index fd8e6418a0d3..be51e7068dcd 100644
--- a/fs/xfs/libxfs/xfs_attr.c
+++ b/fs/xfs/libxfs/xfs_attr.c
@@ -396,6 +396,7 @@ xfs_attr_set(
struct xfs_trans_res tres;
bool rsvd = (args->attr_filter & XFS_ATTR_ROOT);
int error, local;
+ int rmt_blks = 0;
unsigned int total;

if (XFS_FORCED_SHUTDOWN(dp->i_mount))
@@ -442,11 +443,15 @@ xfs_attr_set(
tres.tr_logcount = XFS_ATTRSET_LOG_COUNT;
tres.tr_logflags = XFS_TRANS_PERM_LOG_RES;
total = args->total;
+
+ if (!local)
+ rmt_blks = xfs_attr3_rmt_blocks(mp, args->valuelen);
} else {
XFS_STATS_INC(mp, xs_attr_remove);

tres = M_RES(mp)->tr_attrrm;
total = XFS_ATTRRM_SPACE_RES(mp);
+ rmt_blks = xfs_attr3_rmt_blocks(mp, XFS_XATTR_SIZE_MAX);
}

/*
@@ -460,6 +465,14 @@ xfs_attr_set(

xfs_ilock(dp, XFS_ILOCK_EXCL);
xfs_trans_ijoin(args->trans, dp, 0);
+
+ if (args->value || xfs_inode_hasattr(dp)) {
+ error = xfs_iext_count_may_overflow(dp, XFS_ATTR_FORK,
+ XFS_IEXT_ATTR_MANIP_CNT(rmt_blks));
+ if (error)
+ goto out_trans_cancel;
+ }
+
if (args->value) {
unsigned int quota_flags = XFS_QMOPT_RES_REGBLKS;

diff --git a/fs/xfs/libxfs/xfs_inode_fork.h b/fs/xfs/libxfs/xfs_inode_fork.h
index bcac769a7df6..5de2f07d0dd5 100644
--- a/fs/xfs/libxfs/xfs_inode_fork.h
+++ b/fs/xfs/libxfs/xfs_inode_fork.h
@@ -47,6 +47,16 @@ struct xfs_ifork {
*/
#define XFS_IEXT_PUNCH_HOLE_CNT (1)

+/*
+ * Adding/removing an xattr can cause XFS_DA_NODE_MAXDEPTH extents to
+ * be added. One extra extent for dabtree in case a local attr is
+ * large enough to cause a double split. It can also cause extent
+ * count to increase proportional to the size of a remote xattr's
+ * value.
+ */
+#define XFS_IEXT_ATTR_MANIP_CNT(rmt_blks) \
+ (XFS_DA_NODE_MAXDEPTH + max(1, rmt_blks))
+
/*
* Fork handling.
*/
--
2.28.0