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From: Jianchao Wang <jianchao.w.wang@oracle.com>
To: axboe@kernel.dk
Cc: ming.lei@redhat.com, linux-block@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH V6 1/5] blk-mq: refactor the code of issue request directly
Date: Tue, 13 Nov 2018 17:56:52 +0800	[thread overview]
Message-ID: <1542103016-21037-2-git-send-email-jianchao.w.wang@oracle.com> (raw)
In-Reply-To: <1542103016-21037-1-git-send-email-jianchao.w.wang@oracle.com>

Merge blk_mq_try_issue_directly and __blk_mq_try_issue_directly
into one interface to unify the interfaces to issue requests
directly. The merged interface takes over the requests totally,
it could insert, end or do nothing based on the return value of
.queue_rq and 'bypass' parameter. Then caller needn't any other
handling any more.

Signed-off-by: Jianchao Wang <jianchao.w.wang@oracle.com>
---
 block/blk-mq.c | 93 ++++++++++++++++++++++++++++------------------------------
 1 file changed, 45 insertions(+), 48 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 411be60..14b4d06 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1766,78 +1766,75 @@ static blk_status_t __blk_mq_issue_directly(struct blk_mq_hw_ctx *hctx,
 	return ret;
 }
 
-static blk_status_t __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
+static blk_status_t blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
 						struct request *rq,
 						blk_qc_t *cookie,
-						bool bypass_insert)
+						bool bypass)
 {
 	struct request_queue *q = rq->q;
 	bool run_queue = true;
+	blk_status_t ret = BLK_STS_RESOURCE;
+	int srcu_idx;
 
+	hctx_lock(hctx, &srcu_idx);
 	/*
-	 * RCU or SRCU read lock is needed before checking quiesced flag.
+	 * hctx_lock is needed before checking quiesced flag.
 	 *
-	 * When queue is stopped or quiesced, ignore 'bypass_insert' from
-	 * blk_mq_request_issue_directly(), and return BLK_STS_OK to caller,
-	 * and avoid driver to try to dispatch again.
+	 * When queue is stopped or quiesced, ignore 'bypass', insert
+	 * and return BLK_STS_OK to caller, and avoid driver to try to
+	 * dispatch again.
 	 */
-	if (blk_mq_hctx_stopped(hctx) || blk_queue_quiesced(q)) {
+	if (unlikely(blk_mq_hctx_stopped(hctx) || blk_queue_quiesced(q))) {
 		run_queue = false;
-		bypass_insert = false;
-		goto insert;
+		bypass = false;
+		goto out_unlock;
 	}
 
-	if (q->elevator && !bypass_insert)
-		goto insert;
+	/*
+	 * Bypass the potential scheduler on the bottom device.
+	 */
+	if (unlikely(q->elevator && !bypass))
+		goto out_unlock;
 
-	if (!blk_mq_get_dispatch_budget(hctx))
-		goto insert;
+	if (unlikely(!blk_mq_get_dispatch_budget(hctx)))
+		goto out_unlock;
 
-	if (!blk_mq_get_driver_tag(rq)) {
+	if (unlikely(!blk_mq_get_driver_tag(rq))) {
 		blk_mq_put_dispatch_budget(hctx);
-		goto insert;
+		goto out_unlock;
 	}
 
-	return __blk_mq_issue_directly(hctx, rq, cookie);
-insert:
-	if (bypass_insert)
-		return BLK_STS_RESOURCE;
-
-	blk_mq_sched_insert_request(rq, false, run_queue, false);
-	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);
+	ret = __blk_mq_issue_directly(hctx, rq, cookie);
 
-	hctx_lock(hctx, &srcu_idx);
+out_unlock:
+	hctx_unlock(hctx, srcu_idx);
 
-	ret = __blk_mq_try_issue_directly(hctx, rq, cookie, false);
-	if (ret == BLK_STS_RESOURCE || ret == BLK_STS_DEV_RESOURCE)
-		blk_mq_sched_insert_request(rq, false, true, false);
-	else if (ret != BLK_STS_OK)
-		blk_mq_end_request(rq, ret);
+	switch (ret) {
+	case BLK_STS_OK:
+		break;
+	case BLK_STS_DEV_RESOURCE:
+	case BLK_STS_RESOURCE:
+		if (!bypass) {
+			blk_mq_sched_insert_request(rq, false, run_queue, false);
+			ret = BLK_STS_OK;
+		}
+		break;
+	default:
+		if (!bypass) {
+			blk_mq_end_request(rq, ret);
+			ret = BLK_STS_OK;
+		}
+		break;
+	}
 
-	hctx_unlock(hctx, srcu_idx);
+	return ret;
 }
 
 blk_status_t blk_mq_request_issue_directly(struct request *rq)
 {
-	blk_status_t ret;
-	int srcu_idx;
 	blk_qc_t unused_cookie;
-	struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
 
-	hctx_lock(hctx, &srcu_idx);
-	ret = __blk_mq_try_issue_directly(hctx, rq, &unused_cookie, true);
-	hctx_unlock(hctx, srcu_idx);
-
-	return ret;
+	return blk_mq_try_issue_directly(rq->mq_hctx, rq, &unused_cookie, true);
 }
 
 void blk_mq_try_issue_list_directly(struct blk_mq_hw_ctx *hctx,
@@ -1958,13 +1955,13 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
 		if (same_queue_rq) {
 			data.hctx = same_queue_rq->mq_hctx;
 			blk_mq_try_issue_directly(data.hctx, same_queue_rq,
-					&cookie);
+					&cookie, false);
 		}
 	} else if ((q->nr_hw_queues > 1 && is_sync) || (!q->elevator &&
 			!data.hctx->dispatch_busy)) {
 		blk_mq_put_ctx(data.ctx);
 		blk_mq_bio_to_request(rq, bio);
-		blk_mq_try_issue_directly(data.hctx, rq, &cookie);
+		blk_mq_try_issue_directly(data.hctx, rq, &cookie, false);
 	} else {
 		blk_mq_put_ctx(data.ctx);
 		blk_mq_bio_to_request(rq, bio);
-- 
2.7.4


  reply	other threads:[~2018-11-13  9:57 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-13  9:56 [PATCH V6 0/5] blk-mq: refactor and fix on " Jianchao Wang
2018-11-13  9:56 ` Jianchao Wang [this message]
2018-11-13  9:56 ` [PATCH V6 2/5] blk-mq: fix issue directly case when q is stopped or quiesced Jianchao Wang
2018-11-13  9:56 ` [PATCH V6 3/5] blk-mq: ensure hctx to be ran on mapped cpu when issue directly Jianchao Wang
2018-11-13 13:44   ` Jens Axboe
2018-11-14  2:15     ` jianchao.wang
2018-11-14  3:02       ` Ming Lei
2018-11-14  3:38         ` jianchao.wang
2018-11-13  9:56 ` [PATCH V6 4/5] blk-mq: issue directly with bypass 'false' in blk_mq_sched_insert_requests Jianchao Wang
2018-11-13  9:56 ` [PATCH V6 5/5] blk-mq: replace and kill blk_mq_request_issue_directly Jianchao Wang

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