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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: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jens Axboe <axboe@suse.de>
This commit is contained in:
Tejun Heo 2005-10-20 16:46:23 +02:00 committed by Jens Axboe
parent b4878f245e
commit 06b86245c0
2 changed files with 21 additions and 25 deletions
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43
drivers/block/elevator.c
View File

@ -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)

3
include/linux/blkdev.h
View File

@ -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);