diff --git a/fs/btrfs/disk-io.h b/fs/btrfs/disk-io.h
index c99d0a8f..2bb5f59 100644
--- a/fs/btrfs/disk-io.h
+++ b/fs/btrfs/disk-io.h
@@ -86,6 +86,8 @@
 int btrfs_add_log_tree(struct btrfs_trans_handle *trans,
 		       struct btrfs_root *root);
 
+struct btrfs_root *btrfs_alloc_root(struct btrfs_fs_info *fs_info);
+
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 void btrfs_init_lockdep(void);
 void btrfs_set_buffer_lockdep_class(u64 objectid,