Commit 1b47f531 authored by Jens Axboe's avatar Jens Axboe Committed by Jens Axboe
Browse files

[PATCH] generic dispatch fixes 



- Split elv_dispatch_insert() into two functions
- Rename rq_last_sector() to rq_end_sector()

Signed-off-by: default avatarJens Axboe <axboe@suse.de>
parent 8922e16c

drivers/block/elevator.c

+12 −21
Original line number Diff line number Diff line
@@ -40,11 +40,6 @@ 
static DEFINE_SPINLOCK(elv_list_lock);

static LIST_HEAD(elv_list);



static inline sector_t rq_last_sector(struct request *rq)

{

	return rq->sector + rq->nr_sectors;

}



/*

 * can we safely merge with this request?

 */
@@ -148,7 +143,7 @@ static int elevator_attach(request_queue_t *q, struct elevator_type *e, 
	INIT_LIST_HEAD(&q->queue_head);

	q->last_merge = NULL;

	q->elevator = eq;

	q->last_sector = 0;

	q->end_sector = 0;

	q->boundary_rq = NULL;

	q->max_back_kb = 0;
@@ -233,26 +228,22 @@ void elevator_exit(elevator_t *e) 
	kfree(e);

}



void elv_dispatch_insert_tail(request_queue_t *q, struct request *rq)

{

}



/*

 * Insert rq into dispatch queue of q.  Queue lock must be held on

 * entry.  If sort != 0, rq is sort-inserted; otherwise, rq will be

 * appended to the dispatch queue.  To be used by specific elevators.

 */

void elv_dispatch_insert(request_queue_t *q, struct request *rq, int sort)

void elv_dispatch_sort(request_queue_t *q, struct request *rq)

{

	sector_t boundary;

	unsigned max_back;

	struct list_head *entry;



	if (!sort) {

		/* Specific elevator is performing sort.  Step away. */

		q->last_sector = rq_last_sector(rq);

		q->boundary_rq = rq;

		list_add_tail(&rq->queuelist, &q->queue_head);

		return;

	}



	boundary = q->last_sector;

	boundary = q->end_sector;

	max_back = q->max_back_kb * 2;

	boundary = boundary > max_back ? boundary - max_back : 0;
@@ -343,10 +334,10 @@ void __elv_add_request(request_queue_t *q, struct request *rq, int where, 
			where = ELEVATOR_INSERT_BACK;



		/*

		 * this request is scheduling boundary, update last_sector

		 * this request is scheduling boundary, update end_sector

		 */

		if (blk_fs_request(rq)) {

			q->last_sector = rq_last_sector(rq);

			q->end_sector = rq_end_sector(rq);

			q->boundary_rq = rq;

		}

	}
@@ -479,7 +470,7 @@ struct request *elv_next_request(request_queue_t *q) 
			q->last_merge = NULL;



		if (!q->boundary_rq || q->boundary_rq == rq) {

			q->last_sector = rq_last_sector(rq);

			q->end_sector = rq_end_sector(rq);

			q->boundary_rq = NULL;

		}
@@ -802,7 +793,7 @@ ssize_t elv_iosched_show(request_queue_t *q, char *name) 
	return len;

}



EXPORT_SYMBOL(elv_dispatch_insert);

EXPORT_SYMBOL(elv_dispatch_sort);

EXPORT_SYMBOL(elv_add_request);

EXPORT_SYMBOL(__elv_add_request);

EXPORT_SYMBOL(elv_requeue_request);

include/linux/blkdev.h

+12 −1
Original line number Diff line number Diff line
@@ -337,7 +337,7 @@ struct request_queue 
	/*

	 * Dispatch queue sorting

	 */

	sector_t		last_sector;

	sector_t		end_sector;

	struct request		*boundary_rq;

	unsigned int		max_back_kb;
@@ -624,6 +624,17 @@ static inline void blkdev_dequeue_request(struct request *req) 
	elv_dequeue_request(req->q, req);

}



/*

 * This should be in elevator.h, but that requires pulling in rq and q

 */

static inline void elv_dispatch_add_tail(struct request_queue *q,

					 struct request *rq)

{

	q->end_sector = rq_end_sector(rq);

	q->boundary_rq = rq;

	list_add_tail(&rq->queuelist, &q->queue_head);

}



/*

 * Access functions for manipulating queue properties

 */

include/linux/elevator.h

+3 −1
Original line number Diff line number Diff line
@@ -79,7 +79,7 @@ struct elevator_queue 
/*

 * block elevator interface

 */

extern void elv_dispatch_insert(request_queue_t *, struct request *, int);

extern void elv_dispatch_sort(request_queue_t *, struct request *);

extern void elv_add_request(request_queue_t *, struct request *, int, int);

extern void __elv_add_request(request_queue_t *, struct request *, int, int);

extern int elv_merge(request_queue_t *, struct request **, struct bio *);
@@ -140,4 +140,6 @@ enum { 
	ELV_MQUEUE_MUST,

};



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



#endif