2 files changed, 10 insertions, 0 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 851f2355f3c8..8b851ac7c3fa 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1061,6 +1061,12 @@ struct btrfs_block_group_item {
         __le64 flags;
 } __attribute__ ((__packed__));
 
+#define BTRFS_QGROUP_LEVEL_SHIFT                48
+static inline u64 btrfs_qgroup_level(u64 qgroupid)
+{
+        return qgroupid >> BTRFS_QGROUP_LEVEL_SHIFT;
+}
+
 /*
  * is subvolume quota turned on?
  */
diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
index 464d1e237512..4fb9610beec7 100644
--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -1009,6 +1009,10 @@ int btrfs_add_qgroup_relation(struct btrfs_trans_handle *trans,
         struct btrfs_qgroup_list *list;
         int ret = 0;
 
+        /* Check the level of src and dst first */
+        if (btrfs_qgroup_level(src) >= btrfs_qgroup_level(dst))
+                return -EINVAL;
+
         mutex_lock(&fs_info->qgroup_ioctl_lock);
         quota_root = fs_info->quota_root;
         if (!quota_root) {