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Commit 06b86245 authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe
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[PATCH] 03/05 move last_merge handlin into generic elevator code 



Currently, both generic elevator code and specific ioscheds
participate in the management and usage of last_merge.  This
and the following patches move last_merge handling into
generic elevator code.

Signed-off-by: default avatarTejun Heo <htejun@gmail.com>
Signed-off-by: default avatarJens Axboe <axboe@suse.de>
parent b4878f24

drivers/block/elevator.c

+18 −25
Original line number Diff line number Diff line
@@ -83,15 +83,6 @@ inline int elv_try_merge(struct request *__rq, struct bio *bio) 
}

EXPORT_SYMBOL(elv_try_merge);



inline int elv_try_last_merge(request_queue_t *q, struct bio *bio)

{

	if (q->last_merge)

		return elv_try_merge(q->last_merge, bio);



	return ELEVATOR_NO_MERGE;

}

EXPORT_SYMBOL(elv_try_last_merge);



static struct elevator_type *elevator_find(const char *name)

{

	struct elevator_type *e = NULL;
@@ -239,6 +230,9 @@ void elv_dispatch_sort(request_queue_t *q, struct request *rq) 
	unsigned max_back;

	struct list_head *entry;



	if (q->last_merge == rq)

		q->last_merge = NULL;



	boundary = q->end_sector;

	max_back = q->max_back_kb * 2;

	boundary = boundary > max_back ? boundary - max_back : 0;
@@ -265,6 +259,15 @@ void elv_dispatch_sort(request_queue_t *q, struct request *rq) 
int elv_merge(request_queue_t *q, struct request **req, struct bio *bio)

{

	elevator_t *e = q->elevator;

	int ret;



	if (q->last_merge) {

		ret = elv_try_merge(q->last_merge, bio);

		if (ret != ELEVATOR_NO_MERGE) {

			*req = q->last_merge;

			return ret;

		}

	}



	if (e->ops->elevator_merge_fn)

		return e->ops->elevator_merge_fn(q, req, bio);
@@ -278,6 +281,8 @@ void elv_merged_request(request_queue_t *q, struct request *rq) 


	if (e->ops->elevator_merged_fn)

		e->ops->elevator_merged_fn(q, rq);



	q->last_merge = rq;

}



void elv_merge_requests(request_queue_t *q, struct request *rq,
@@ -285,11 +290,10 @@ void elv_merge_requests(request_queue_t *q, struct request *rq, 
{

	elevator_t *e = q->elevator;



	if (q->last_merge == next)

		q->last_merge = NULL;



	if (e->ops->elevator_merge_req_fn)

		e->ops->elevator_merge_req_fn(q, rq, next);



	q->last_merge = rq;

}



void elv_requeue_request(request_queue_t *q, struct request *rq)
@@ -384,6 +388,8 @@ void __elv_add_request(request_queue_t *q, struct request *rq, int where, 
		BUG_ON(!blk_fs_request(rq));

		rq->flags |= REQ_SORTED;

		q->elevator->ops->elevator_add_req_fn(q, rq);

		if (q->last_merge == NULL && rq_mergeable(rq))

			q->last_merge = rq;

		break;



	default:
@@ -462,9 +468,6 @@ struct request *elv_next_request(request_queue_t *q) 
			rq->flags |= REQ_STARTED;

		}



		if (rq == q->last_merge)

			q->last_merge = NULL;



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

			q->end_sector = rq_end_sector(rq);

			q->boundary_rq = NULL;
@@ -518,16 +521,6 @@ void elv_dequeue_request(request_queue_t *q, struct request *rq) 
	 */

	if (blk_account_rq(rq))

		q->in_flight++;



	/*

	 * the main clearing point for q->last_merge is on retrieval of

	 * request by driver (it calls elv_next_request()), but it _can_

	 * also happen here if a request is added to the queue but later

	 * deleted without ever being given to driver (merged with another

	 * request).

	 */

	if (rq == q->last_merge)

		q->last_merge = NULL;

}



int elv_queue_empty(request_queue_t *q)

include/linux/blkdev.h

+3 −0
Original line number Diff line number Diff line
@@ -630,6 +630,9 @@ static inline void blkdev_dequeue_request(struct request *req) 
static inline void elv_dispatch_add_tail(struct request_queue *q,

					 struct request *rq)

{

	if (q->last_merge == rq)

		q->last_merge = NULL;



	q->end_sector = rq_end_sector(rq);

	q->boundary_rq = rq;

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