From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7B46AC433E2 for ; Sat, 5 Sep 2020 11:27:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 47A372074B for ; Sat, 5 Sep 2020 11:27:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728503AbgIEL1w (ORCPT ); Sat, 5 Sep 2020 07:27:52 -0400 Received: from szxga07-in.huawei.com ([45.249.212.35]:47926 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728472AbgIEL1e (ORCPT ); Sat, 5 Sep 2020 07:27:34 -0400 Received: from DGGEMS410-HUB.china.huawei.com (unknown [172.30.72.59]) by Forcepoint Email with ESMTP id 41F7DFADDC2DB11BBDDD; Sat, 5 Sep 2020 19:26:40 +0800 (CST) Received: from code-website.localdomain (10.175.127.227) by DGGEMS410-HUB.china.huawei.com (10.3.19.210) with Microsoft SMTP Server id 14.3.487.0; Sat, 5 Sep 2020 19:26:29 +0800 From: yangerkun To: CC: , , , , , Subject: [PATCH v2] blk-mq: call commit_rqs while list empty but error happen Date: Sat, 5 Sep 2020 19:25:56 +0800 Message-ID: <20200905112556.1735962-1-yangerkun@huawei.com> X-Mailer: git-send-email 2.25.4 MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Content-Type: text/plain; charset=US-ASCII X-Originating-IP: [10.175.127.227] X-CFilter-Loop: Reflected Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Blk-mq should call commit_rqs once 'bd.last != true' and no more request will come(so virtscsi can kick the virtqueue, e.g.). We already do that in 'blk_mq_dispatch_rq_list/blk_mq_try_issue_list_directly' while list not empty and 'queued > 0'. However, we can seen the same scene once the last request in list call queue_rq and return error like BLK_STS_IOERR which will not requeue the request, and lead that list empty but need call commit_rqs too(Or the request for virtscsi will stay timeout until other request kick virtqueue). We found this problem by do fsstress test with offline/online virtscsi device repeat quickly. Fixes: d666ba98f849 ("blk-mq: add mq_ops->commit_rqs()") Reported-by: zhangyi (F) Signed-off-by: yangerkun --- block/blk-mq.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) v1->v2: delete the comment diff --git a/block/blk-mq.c b/block/blk-mq.c index b3d2785eefe9..cdced4aca2e8 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1412,6 +1412,11 @@ bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list, hctx->dispatched[queued_to_index(queued)]++; + /* If we didn't flush the entire list, we could have told the driver + * there was more coming, but that turned out to be a lie. + */ + if ((!list_empty(list) || errors) && q->mq_ops->commit_rqs && queued) + q->mq_ops->commit_rqs(hctx); /* * Any items that need requeuing? Stuff them into hctx->dispatch, * that is where we will continue on next queue run. @@ -1425,14 +1430,6 @@ bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list, blk_mq_release_budgets(q, nr_budgets); - /* - * If we didn't flush the entire list, we could have told - * the driver there was more coming, but that turned out to - * be a lie. - */ - if (q->mq_ops->commit_rqs && queued) - q->mq_ops->commit_rqs(hctx); - spin_lock(&hctx->lock); list_splice_tail_init(list, &hctx->dispatch); spin_unlock(&hctx->lock); @@ -2079,6 +2076,7 @@ void blk_mq_try_issue_list_directly(struct blk_mq_hw_ctx *hctx, struct list_head *list) { int queued = 0; + int errors = 0; while (!list_empty(list)) { blk_status_t ret; @@ -2095,6 +2093,7 @@ void blk_mq_try_issue_list_directly(struct blk_mq_hw_ctx *hctx, break; } blk_mq_end_request(rq, ret); + errors++; } else queued++; } @@ -2104,7 +2103,8 @@ void blk_mq_try_issue_list_directly(struct blk_mq_hw_ctx *hctx, * the driver there was more coming, but that turned out to * be a lie. */ - if (!list_empty(list) && hctx->queue->mq_ops->commit_rqs && queued) + if ((!list_empty(list) || errors) && + hctx->queue->mq_ops->commit_rqs && queued) hctx->queue->mq_ops->commit_rqs(hctx); } -- 2.25.4