From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753923AbeAREHX (ORCPT ); Wed, 17 Jan 2018 23:07:23 -0500 Received: from mx1.redhat.com ([209.132.183.28]:54404 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752659AbeAREHV (ORCPT ); Wed, 17 Jan 2018 23:07:21 -0500 From: Ming Lei To: Jens Axboe , linux-block@vger.kernel.org, Mike Snitzer , dm-devel@redhat.com Cc: Christoph Hellwig , Bart Van Assche , linux-kernel@vger.kernel.org, Ming Lei Subject: [PATCH] blk-mq: don't dispatch request in blk_mq_request_direct_issue if queue is busy Date: Thu, 18 Jan 2018 12:06:59 +0800 Message-Id: <20180118040659.20202-1-ming.lei@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If we run into blk_mq_request_direct_issue(), when queue is busy, we don't want to dispatch this request into hctx->dispatch_list, and what we need to do is to return the queue busy info to caller, so that caller can deal with it well. Fixes: 396eaf21ee ("blk-mq: improve DM's blk-mq IO merging via blk_insert_cloned_request feedback") Reported-by: Laurence Oberman Reviewed-by: Mike Snitzer Signed-off-by: Ming Lei --- block/blk-mq.c | 22 ++++++++++------------ 1 file changed, 10 insertions(+), 12 deletions(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index 4d4af8d712da..1af7fa70993b 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1856,15 +1856,6 @@ static blk_status_t __blk_mq_issue_directly(struct blk_mq_hw_ctx *hctx, return ret; } -static void __blk_mq_fallback_to_insert(struct request *rq, - bool run_queue, bool bypass_insert) -{ - if (!bypass_insert) - blk_mq_sched_insert_request(rq, false, run_queue, false); - else - blk_mq_request_bypass_insert(rq, run_queue); -} - static blk_status_t __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx, struct request *rq, blk_qc_t *cookie, @@ -1873,9 +1864,16 @@ static blk_status_t __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx, struct request_queue *q = rq->q; bool run_queue = true; - /* RCU or SRCU read lock is needed before checking quiesced flag */ + /* + * RCU or SRCU read lock is needed before checking quiesced flag. + * + * When queue is stopped or quiesced, ignore 'bypass_insert' from + * blk_mq_request_direct_issue(), 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)) { run_queue = false; + bypass_insert = false; goto insert; } @@ -1892,10 +1890,10 @@ static blk_status_t __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx, return __blk_mq_issue_directly(hctx, rq, cookie); insert: - __blk_mq_fallback_to_insert(rq, run_queue, bypass_insert); if (bypass_insert) return BLK_STS_RESOURCE; + blk_mq_sched_insert_request(rq, false, run_queue, false); return BLK_STS_OK; } @@ -1911,7 +1909,7 @@ static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx, ret = __blk_mq_try_issue_directly(hctx, rq, cookie, false); if (ret == BLK_STS_RESOURCE) - __blk_mq_fallback_to_insert(rq, true, false); + blk_mq_sched_insert_request(rq, false, true, false); else if (ret != BLK_STS_OK) blk_mq_end_request(rq, ret); -- 2.9.5