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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 ECAB3C4360C for ; Mon, 14 Oct 2019 01:51:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CBE6120650 for ; Mon, 14 Oct 2019 01:51:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729726AbfJNBvR (ORCPT ); Sun, 13 Oct 2019 21:51:17 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36878 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729630AbfJNBvR (ORCPT ); Sun, 13 Oct 2019 21:51:17 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id E5D48307D8BE; Mon, 14 Oct 2019 01:51:16 +0000 (UTC) Received: from localhost (ovpn-8-17.pek2.redhat.com [10.72.8.17]) by smtp.corp.redhat.com (Postfix) with ESMTP id 7CFFC5D6A3; Mon, 14 Oct 2019 01:51:13 +0000 (UTC) From: Ming Lei To: Jens Axboe Cc: linux-block@vger.kernel.org, Ming Lei , John Garry , Bart Van Assche , Hannes Reinecke , Christoph Hellwig , Thomas Gleixner , Keith Busch Subject: [PATCH V4 4/5] blk-mq: re-submit IO in case that hctx is dead Date: Mon, 14 Oct 2019 09:50:42 +0800 Message-Id: <20191014015043.25029-5-ming.lei@redhat.com> In-Reply-To: <20191014015043.25029-1-ming.lei@redhat.com> References: <20191014015043.25029-1-ming.lei@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.48]); Mon, 14 Oct 2019 01:51:17 +0000 (UTC) Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org When all CPUs in one hctx are offline, we shouldn't run this hw queue for completing request any more. So steal bios from the request, and resubmit them, and finally free the request in blk_mq_hctx_notify_dead(). Cc: John Garry Cc: Bart Van Assche Cc: Hannes Reinecke Cc: Christoph Hellwig Cc: Thomas Gleixner Cc: Keith Busch Signed-off-by: Ming Lei --- block/blk-mq.c | 54 ++++++++++++++++++++++++++++++++++++++++++++------ 1 file changed, 48 insertions(+), 6 deletions(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index 3384242202eb..17f0a9ef32a8 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -2268,10 +2268,34 @@ static int blk_mq_hctx_notify_online(unsigned int cpu, struct hlist_node *node) return 0; } +static void blk_mq_resubmit_io(struct request *rq) +{ + struct bio_list list; + struct bio *bio; + + bio_list_init(&list); + blk_steal_bios(&list, rq); + + /* + * Free the old empty request before submitting bio for avoiding + * potential deadlock + */ + blk_mq_cleanup_rq(rq); + blk_mq_end_request(rq, 0); + + while (true) { + bio = bio_list_pop(&list); + if (!bio) + break; + + generic_make_request(bio); + } +} + /* - * 'cpu' is going away. splice any existing rq_list entries from this - * software queue to the hw queue dispatch list, and ensure that it - * gets run. + * 'cpu' has gone away. If this hctx is dead, we can't dispatch request + * to the hctx any more, so steal bios from requests of this hctx, and + * re-submit them to the request queue, and free these requests finally. */ static int blk_mq_hctx_notify_dead(unsigned int cpu, struct hlist_node *node) { @@ -2279,6 +2303,8 @@ static int blk_mq_hctx_notify_dead(unsigned int cpu, struct hlist_node *node) struct blk_mq_ctx *ctx; LIST_HEAD(tmp); enum hctx_type type; + bool hctx_dead; + struct request *rq; hctx = hlist_entry_safe(node, struct blk_mq_hw_ctx, cpuhp_dead); ctx = __blk_mq_get_ctx(hctx->queue, cpu); @@ -2286,6 +2312,9 @@ static int blk_mq_hctx_notify_dead(unsigned int cpu, struct hlist_node *node) clear_bit(BLK_MQ_S_INTERNAL_STOPPED, &hctx->state); + hctx_dead = cpumask_first_and(hctx->cpumask, cpu_online_mask) >= + nr_cpu_ids; + spin_lock(&ctx->lock); if (!list_empty(&ctx->rq_lists[type])) { list_splice_init(&ctx->rq_lists[type], &tmp); @@ -2293,14 +2322,27 @@ static int blk_mq_hctx_notify_dead(unsigned int cpu, struct hlist_node *node) } spin_unlock(&ctx->lock); - if (list_empty(&tmp)) + if (!hctx_dead) { + if (list_empty(&tmp)) + return 0; + spin_lock(&hctx->lock); + list_splice_tail_init(&tmp, &hctx->dispatch); + spin_unlock(&hctx->lock); + blk_mq_run_hw_queue(hctx, true); return 0; + } + /* requests in dispatch list has to be re-submitted too */ spin_lock(&hctx->lock); - list_splice_tail_init(&tmp, &hctx->dispatch); + list_splice_tail_init(&hctx->dispatch, &tmp); spin_unlock(&hctx->lock); - blk_mq_run_hw_queue(hctx, true); + while (!list_empty(&tmp)) { + rq = list_entry(tmp.next, struct request, queuelist); + list_del_init(&rq->queuelist); + blk_mq_resubmit_io(rq); + } + return 0; } -- 2.20.1