xfs: Check for extent overflow when adding dir entries

Directory entry addition 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.

Signed-off-by: Chandan Babu R <chandanrlinux@gmail.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

fs/xfs/libxfs/xfs_inode_fork.h

@@ -47,6 +47,19 @@ struct xfs_ifork {
  */
 #define XFS_IEXT_PUNCH_HOLE_CNT		(1)
 
+/*
+ * Directory entry addition 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.
  */

fs/xfs/xfs_inode.c

@@ -1042,6 +1042,11 @@ 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
@@ -1258,6 +1263,11 @@ 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

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.
 	 */