2 files changed, 9 insertions, 1 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 8b851ac7c3fa..6f364e1d8d3d 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -4219,7 +4219,8 @@ int btree_readahead_hook(struct btrfs_root *root, struct extent_buffer *eb,
 static inline int is_fstree(u64 rootid)
 {
         if (rootid == BTRFS_FS_TREE_OBJECTID ||
-            (s64)rootid >= (s64)BTRFS_FIRST_FREE_OBJECTID)
+            ((s64)rootid >= (s64)BTRFS_FIRST_FREE_OBJECTID &&
+              !btrfs_qgroup_level(rootid)))
                 return 1;
         return 0;
 }
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 2e66d8e76f32..e38b645c5015 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -456,6 +456,13 @@ static noinline int create_subvol(struct inode *dir,
         if (ret)
                 return ret;
 
+        /*
+         * Don't create subvolume whose level is not zero. Or qgroup will be
+         * screwed up since it assume subvolme qgroup's level to be 0.
+         */
+        if (btrfs_qgroup_level(objectid))
+                return -ENOSPC;
+
         btrfs_init_block_rsv(&block_rsv, BTRFS_BLOCK_RSV_TEMP);
         /*
          * The same as the snapshot creation, please see the comment