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blk-mq: abstract out blk-mq-sched rq list iteration bio merge helper 

No functional changes in this patch, just a prep patch for utilizing
this in an IO scheduler.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Omar Sandoval <osandov@fb.com>
This commit is contained in:
Jens Axboe 2018-05-30 15:26:07 +08:00
parent 5de815a7ee
commit 9c55873464
2 changed files with 26 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

34
block/blk-mq-sched.c
View File

@ -268,19 +268,16 @@ bool blk_mq_sched_try_merge(struct request_queue *q, struct bio *bio,
EXPORT_SYMBOL_GPL(blk_mq_sched_try_merge);
/*
* Reverse check our software queue for entries that we could potentially
* merge with. Currently includes a hand-wavy stop count of 8, to not spend
* too much time checking for merges.
* Iterate list of requests and see if we can merge this bio with any
* of them.
*/
static bool blk_mq_attempt_merge(struct request_queue *q,
struct blk_mq_ctx *ctx, struct bio *bio)
bool blk_mq_bio_list_merge(struct request_queue *q, struct list_head *list,
struct bio *bio)
{
struct request *rq;
int checked = 8;
lockdep_assert_held(&ctx->lock);
list_for_each_entry_reverse(rq, &ctx->rq_list, queuelist) {
list_for_each_entry_reverse(rq, list, queuelist) {
bool merged = false;
if (!checked--)
@ -305,13 +302,30 @@ static bool blk_mq_attempt_merge(struct request_queue *q,
continue;
}
if (merged)
ctx->rq_merged++;
return merged;
}
return false;
}
EXPORT_SYMBOL_GPL(blk_mq_bio_list_merge);
/*
* Reverse check our software queue for entries that we could potentially
* merge with. Currently includes a hand-wavy stop count of 8, to not spend
* too much time checking for merges.
*/
static bool blk_mq_attempt_merge(struct request_queue *q,
struct blk_mq_ctx *ctx, struct bio *bio)
{
lockdep_assert_held(&ctx->lock);
if (blk_mq_bio_list_merge(q, &ctx->rq_list, bio)) {
ctx->rq_merged++;
return true;
}
return false;
}
bool __blk_mq_sched_bio_merge(struct request_queue *q, struct bio *bio)
{

3
include/linux/blk-mq.h
View File

@ -259,7 +259,8 @@ void blk_mq_add_to_requeue_list(struct request *rq, bool at_head,
void blk_mq_kick_requeue_list(struct request_queue *q);
void blk_mq_delay_kick_requeue_list(struct request_queue *q, unsigned long msecs);
void blk_mq_complete_request(struct request *rq);
bool blk_mq_bio_list_merge(struct request_queue *q, struct list_head *list,
struct bio *bio);
bool blk_mq_queue_stopped(struct request_queue *q);
void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx);
void blk_mq_start_hw_queue(struct blk_mq_hw_ctx *hctx);