btrfs: move checks for DUMMY_ROOT into a helper

Signed-off-by: David Sterba <dsterba@suse.cz>

fs/btrfs/qgroup.c

@@ -539,10 +539,9 @@ static int add_qgroup_item(struct btrfs_trans_handle *trans,
 	struct extent_buffer *leaf;
 	struct btrfs_key key;
 
-#ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
-	if (unlikely(test_bit(BTRFS_ROOT_DUMMY_ROOT, &quota_root->state)))
+	if (btrfs_test_is_dummy_root(quota_root))
 		return 0;
-#endif
+
 	path = btrfs_alloc_path();
 	if (!path)
 		return -ENOMEM;
@@ -698,10 +697,9 @@ static int update_qgroup_info_item(struct btrfs_trans_handle *trans,
 	int ret;
 	int slot;
 
-#ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
-	if (unlikely(test_bit(BTRFS_ROOT_DUMMY_ROOT, &root->state)))
+	if (btrfs_test_is_dummy_root(root))
 		return 0;
-#endif
+
 	key.objectid = 0;
 	key.type = BTRFS_QGROUP_INFO_KEY;
 	key.offset = qgroup->qgroupid;