From patchwork Wed Jan 4 14:22:56 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kemeng Shi X-Patchwork-Id: 13088209 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D9457C4332F for ; Wed, 4 Jan 2023 06:24:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230241AbjADGYb (ORCPT ); Wed, 4 Jan 2023 01:24:31 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41946 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232799AbjADGYY (ORCPT ); Wed, 4 Jan 2023 01:24:24 -0500 Received: from dggsgout11.his.huawei.com (dggsgout11.his.huawei.com [45.249.212.51]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E168117E01; Tue, 3 Jan 2023 22:24:23 -0800 (PST) Received: from mail02.huawei.com (unknown [172.30.67.153]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTP id 4Nn01Z03kwz4f3pPK; Wed, 4 Jan 2023 14:24:18 +0800 (CST) Received: from huaweicloud.com (unknown [10.175.124.27]) by APP4 (Coremail) with SMTP id gCh0CgDnnbGOG7Vju3lKBA--.23788S12; Wed, 04 Jan 2023 14:24:20 +0800 (CST) From: Kemeng Shi To: axboe@kernel.dk, dwagner@suse.de, hare@suse.de, ming.lei@redhat.com, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org Cc: hch@lst.de, john.garry@huawei.com, jack@suse.cz Subject: [PATCH v2 10/13] blk-mq: remove set of bd->last when get driver tag for next request fails Date: Wed, 4 Jan 2023 22:22:56 +0800 Message-Id: <20230104142259.2673013-11-shikemeng@huaweicloud.com> X-Mailer: git-send-email 2.30.0 In-Reply-To: <20230104142259.2673013-1-shikemeng@huaweicloud.com> References: <20230104142259.2673013-1-shikemeng@huaweicloud.com> MIME-Version: 1.0 X-CM-TRANSID: gCh0CgDnnbGOG7Vju3lKBA--.23788S12 X-Coremail-Antispam: 1UD129KBjvJXoW7ZryrKr17Cr1DAw1rCrWxWFg_yoW8Kr18pF WfJayakr45XF40qFW8AwsrWF45Jw4DAryayrsxC34Sqrn8Crs2gFyUJ3yUZa4SvrWkCrsI gr4qgr1DZr48XFDanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUBIb4IE77IF4wAFF20E14v26rWj6s0DM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M280x2IEY4vEnII2IxkI6r1a6r45M2 8IrcIa0xkI8VA2jI8067AKxVWUAVCq3wA2048vs2IY020Ec7CjxVAFwI0_Xr0E3s1l8cAv FVAK0II2c7xJM28CjxkF64kEwVA0rcxSw2x7M28EF7xvwVC0I7IYx2IY67AKxVWDJVCq3w A2z4x0Y4vE2Ix0cI8IcVCY1x0267AKxVW8Jr0_Cr1UM28EF7xvwVC2z280aVAFwI0_GcCE 3s1l84ACjcxK6I8E87Iv6xkF7I0E14v26rxl6s0DM2AIxVAIcxkEcVAq07x20xvEncxIr2 1l5I8CrVACY4xI64kE6c02F40Ex7xfMcIj6xIIjxv20xvE14v26r1j6r18McIj6I8E87Iv 67AKxVWUJVW8JwAm72CE4IkC6x0Yz7v_Jr0_Gr1lF7xvr2IYc2Ij64vIr41l42xK82IYc2 Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4xG67AKxVWUJVWUGwC20s02 6x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r1q6r43MIIYrxkI7VAKI48JMIIF0x vE2Ix0cI8IcVAFwI0_Gr0_Xr1lIxAIcVC0I7IYx2IY6xkF7I0E14v26F4j6r4UJwCI42IY 6xAIw20EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aVAFwI0_Gr0_Cr1lIxAIcVC2z280aV CY1x0267AKxVW8JVW8JrUvcSsGvfC2KfnxnUUI43ZEXa7IU0TqcUUUUUU== X-CM-SenderInfo: 5vklyvpphqwq5kxd4v5lfo033gof0z/ X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Commit 113285b473824 ("blk-mq: ensure that bd->last is always set correctly") will set last if we failed to get driver tag for next request to avoid flush miss as we break the list walk and will not send the last request in the list which will be sent with last set normally. This code seems stale now becase the flush introduced is always redundant as: For case tag is really out, we will send a extra flush if we find list is not empty after list walk. For case some tag is freed before retry in blk_mq_prep_dispatch_rq for next, then we can get a tag for next request in retry and flush notified already is not necessary. Just remove these stale codes. Signed-off-by: Kemeng Shi --- block/blk-mq.c | 24 ++---------------------- 1 file changed, 2 insertions(+), 22 deletions(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index c1d4d899f059..882c03a3f0aa 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1917,16 +1917,6 @@ static void blk_mq_update_dispatch_busy(struct blk_mq_hw_ctx *hctx, bool busy) static void blk_mq_handle_dev_resource(struct request *rq, struct list_head *list) { - struct request *next = - list_first_entry_or_null(list, struct request, queuelist); - - /* - * If an I/O scheduler has been configured and we got a driver tag for - * the next request already, free it. - */ - if (next) - blk_mq_put_driver_tag(next); - list_add(&rq->queuelist, list); __blk_mq_requeue_request(rq); } @@ -2009,7 +1999,7 @@ bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list, { enum prep_dispatch prep; struct request_queue *q = hctx->queue; - struct request *rq, *nxt; + struct request *rq; int queued; blk_status_t ret = BLK_STS_OK; LIST_HEAD(zone_list); @@ -2035,17 +2025,7 @@ bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list, list_del_init(&rq->queuelist); bd.rq = rq; - - /* - * Flag last if we have no more requests, or if we have more - * but can't assign a driver tag to it. - */ - if (list_empty(list)) - bd.last = true; - else { - nxt = list_first_entry(list, struct request, queuelist); - bd.last = !blk_mq_get_driver_tag(nxt); - } + bd.last = list_empty(list); /* * once the request is queued to lld, no need to cover the