-extern void print_disk_util(struct disk_util_stat *, struct disk_util_agg *, int terse);
-extern void show_disk_util(int terse, struct json_object *parent);
+extern void print_disk_util(struct disk_util_stat *, struct disk_util_agg *, int terse, struct buf_output *);
+extern void show_disk_util(int terse, struct json_object *parent, struct buf_output *);