-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 *);
-extern void json_array_add_disk_util(struct disk_util_stat *dus,
- struct disk_util_agg *agg, struct json_array *parent);