[PATCH V7 05/14] xfs: Check for extent overflow when adding/removing dir entries

Chandan Babu R
2020-10-19T06:41:27Z

Directory entry addition/removal can cause the following,
1. Data block can be added/removed.
A new extent can cause extent count to increase by 1.
2. Free disk block can be added/removed.
Same behaviour as described above for Data block.
3. Dabtree blocks.
XFS_DA_NODE_MAXDEPTH blocks can be added. Each of these
can be new extents. Hence extent count can increase by
XFS_DA_NODE_MAXDEPTH.

Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Chandan Babu R <chandanrlinux@gmail.com>
---
fs/xfs/libxfs/xfs_inode_fork.h | 13 +++++++++++++
fs/xfs/xfs_inode.c | 27 +++++++++++++++++++++++++++
fs/xfs/xfs_symlink.c | 5 +++++
3 files changed, 45 insertions(+)

diff --git a/fs/xfs/libxfs/xfs_inode_fork.h b/fs/xfs/libxfs/xfs_inode_fork.h
index 5de2f07d0dd5..fd93fdc67ee4 100644
--- a/fs/xfs/libxfs/xfs_inode_fork.h
+++ b/fs/xfs/libxfs/xfs_inode_fork.h
@@ -57,6 +57,19 @@ struct xfs_ifork {
#define XFS_IEXT_ATTR_MANIP_CNT(rmt_blks) \
(XFS_DA_NODE_MAXDEPTH + max(1, rmt_blks))

+/*
+ * Directory entry addition/removal can cause the following,
+ * 1. Data block can be added/removed.
+ * A new extent can cause extent count to increase by 1.
+ * 2. Free disk block can be added/removed.
+ * Same behaviour as described above for Data block.
+ * 3. Dabtree blocks.
+ * XFS_DA_NODE_MAXDEPTH blocks can be added. Each of these can be new
+ * extents. Hence extent count can increase by XFS_DA_NODE_MAXDEPTH.
+ */
+#define XFS_IEXT_DIR_MANIP_CNT(mp) \
+ ((XFS_DA_NODE_MAXDEPTH + 1 + 1) * (mp)->m_dir_geo->fsbcount)
+
/*
* Fork handling.
*/
diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index 2bfbcf28b1bd..5b41ffaf04d7 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -1177,6 +1177,11 @@ xfs_create(
if (error)
goto out_trans_cancel;

+ error = xfs_iext_count_may_overflow(dp, XFS_DATA_FORK,
+ XFS_IEXT_DIR_MANIP_CNT(mp));
+ if (error)
+ goto out_trans_cancel;
+
/*
* A newly created regular or special file just has one directory
* entry pointing to them, but a directory also the "." entry
@@ -1393,6 +1398,11 @@ xfs_link(
xfs_trans_ijoin(tp, sip, XFS_ILOCK_EXCL);
xfs_trans_ijoin(tp, tdp, XFS_ILOCK_EXCL);

+ error = xfs_iext_count_may_overflow(tdp, XFS_DATA_FORK,
+ XFS_IEXT_DIR_MANIP_CNT(mp));
+ if (error)
+ goto error_return;
+
/*
* If we are using project inheritance, we only allow hard link
* creation in our tree when the project IDs are the same; else
@@ -2861,6 +2871,11 @@ xfs_remove(
xfs_trans_ijoin(tp, dp, XFS_ILOCK_EXCL);
xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);

+ error = xfs_iext_count_may_overflow(dp, XFS_DATA_FORK,
+ XFS_IEXT_DIR_MANIP_CNT(mp));
+ if (error)
+ goto out_trans_cancel;
+
/*
* If we're removing a directory perform some additional validation.
*/
@@ -3221,6 +3236,18 @@ xfs_rename(
if (wip)
xfs_trans_ijoin(tp, wip, XFS_ILOCK_EXCL);

+ error = xfs_iext_count_may_overflow(src_dp, XFS_DATA_FORK,
+ XFS_IEXT_DIR_MANIP_CNT(mp));
+ if (error)
+ goto out_trans_cancel;
+
+ if (target_ip == NULL) {
+ error = xfs_iext_count_may_overflow(target_dp, XFS_DATA_FORK,
+ XFS_IEXT_DIR_MANIP_CNT(mp));
+ if (error)
+ goto out_trans_cancel;
+ }
+
/*
* If we are using project inheritance, we only allow renames
* into our tree when the project IDs are the same; else the
diff --git a/fs/xfs/xfs_symlink.c b/fs/xfs/xfs_symlink.c
index 8e88a7ca387e..581a4032a817 100644
--- a/fs/xfs/xfs_symlink.c
+++ b/fs/xfs/xfs_symlink.c
@@ -220,6 +220,11 @@ xfs_symlink(
if (error)
goto out_trans_cancel;

+ error = xfs_iext_count_may_overflow(dp, XFS_DATA_FORK,
+ XFS_IEXT_DIR_MANIP_CNT(mp));
+ if (error)
+ goto out_trans_cancel;
+
/*
* Allocate an inode for the symlink.
*/
--
2.28.0