diff --git a/fs/btrfs/block-rsv.c b/fs/btrfs/block-rsv.c
index 2044f1e18629..507b44d18572 100644
--- a/fs/btrfs/block-rsv.c
+++ b/fs/btrfs/block-rsv.c
@@ -377,6 +377,11 @@ void btrfs_update_global_block_rsv(struct btrfs_fs_info *fs_info)
 	}
 	read_unlock(&fs_info->global_root_lock);
 
+	if (btrfs_fs_compat_ro(fs_info, BLOCK_GROUP_TREE)) {
+		num_bytes += btrfs_root_used(&fs_info->block_group_root->root_item);
+		min_items++;
+	}
+
 	/*
 	 * But we also want to reserve enough space so we can do the fallback
 	 * global reserve for an unlink, which is an additional 5 items (see the