[PATCH] elevator: introduce a way to reuse rq for internal FIFO handling

#define rq_end_sector(rq)	((rq)->sector + (rq)->nr_sectors)

#define rb_entry_rq(node)	rb_entry((node), struct request, rb_node)

/*

 * Hack to reuse the donelist list_head as the fifo time holder while

 * the request is in the io scheduler. Saves an unsigned long in rq.

 */

#define rq_fifo_time(rq)	((unsigned long) (rq)->donelist.next)

#define rq_set_fifo_time(rq,exp)	((rq)->donelist.next = (void *) (exp))

#define rq_entry_fifo(ptr)	list_entry((ptr), struct request, queuelist)

#define rq_fifo_clear(rq)	do {		\

	list_del_init(&(rq)->queuelist);	\

	INIT_LIST_HEAD(&(rq)->donelist);	\

	} while (0)

#endif