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blk-mq: factor out a few helpers from __blk_mq_try_issue_directly

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No functional change.  Just makes code flow more logically.

In following commit, __blk_mq_try_issue_directly() will be used to
return the dispatch result (blk_status_t) to DM.  DM needs this
information to improve IO merging.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Mike Snitzer 2018-01-17 11:25:56 -05:00 committed by Jens Axboe
parent 7df938fbc4
commit 0f95549c0e
1 changed files with 52 additions and 27 deletions
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79
block/blk-mq.c
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@ -1738,9 +1738,9 @@ static blk_qc_t request_to_qc_t(struct blk_mq_hw_ctx *hctx, struct request *rq)
return blk_tag_to_qc_t(rq->internal_tag, hctx->queue_num, true);
}
static void __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
struct request *rq,
blk_qc_t *cookie)
static blk_status_t __blk_mq_issue_directly(struct blk_mq_hw_ctx *hctx,
struct request *rq,
blk_qc_t *cookie)
{
struct request_queue *q = rq->q;
struct blk_mq_queue_data bd = {
@ -1749,6 +1749,43 @@ static void __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
};
blk_qc_t new_cookie;
blk_status_t ret;
new_cookie = request_to_qc_t(hctx, rq);
/*
* For OK queue, we are done. For error, caller may kill it.
* Any other error (busy), just add it to our list as we
* previously would have done.
*/
ret = q->mq_ops->queue_rq(hctx, &bd);
switch (ret) {
case BLK_STS_OK:
*cookie = new_cookie;
break;
case BLK_STS_RESOURCE:
__blk_mq_requeue_request(rq);
break;
default:
*cookie = BLK_QC_T_NONE;
break;
}
return ret;
}
static void __blk_mq_fallback_to_insert(struct blk_mq_hw_ctx *hctx,
struct request *rq,
bool run_queue)
{
blk_mq_sched_insert_request(rq, false, run_queue, false,
hctx->flags & BLK_MQ_F_BLOCKING);
}
static blk_status_t __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
struct request *rq,
blk_qc_t *cookie)
{
struct request_queue *q = rq->q;
bool run_queue = true;
/* RCU or SRCU read lock is needed before checking quiesced flag */
@ -1768,41 +1805,29 @@ static void __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
goto insert;
}
new_cookie = request_to_qc_t(hctx, rq);
/*
* For OK queue, we are done. For error, kill it. Any other
* error (busy), just add it to our list as we previously
* would have done
*/
ret = q->mq_ops->queue_rq(hctx, &bd);
switch (ret) {
case BLK_STS_OK:
*cookie = new_cookie;
return;
case BLK_STS_RESOURCE:
__blk_mq_requeue_request(rq);
goto insert;
default:
*cookie = BLK_QC_T_NONE;
blk_mq_end_request(rq, ret);
return;
}
return __blk_mq_issue_directly(hctx, rq, cookie);
insert:
blk_mq_sched_insert_request(rq, false, run_queue, false,
hctx->flags & BLK_MQ_F_BLOCKING);
__blk_mq_fallback_to_insert(hctx, rq, run_queue);
return BLK_STS_OK;
}
static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
struct request *rq, blk_qc_t *cookie)
{
blk_status_t ret;
int srcu_idx;
might_sleep_if(hctx->flags & BLK_MQ_F_BLOCKING);
hctx_lock(hctx, &srcu_idx);
__blk_mq_try_issue_directly(hctx, rq, cookie);
ret = __blk_mq_try_issue_directly(hctx, rq, cookie);
if (ret == BLK_STS_RESOURCE)
__blk_mq_fallback_to_insert(hctx, rq, true);
else if (ret != BLK_STS_OK)
blk_mq_end_request(rq, ret);
hctx_unlock(hctx, srcu_idx);
}