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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BCBDCC4332F for ; Tue, 18 Oct 2022 08:56:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229572AbiJRI4C (ORCPT ); Tue, 18 Oct 2022 04:56:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46618 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230239AbiJRI4C (ORCPT ); Tue, 18 Oct 2022 04:56:02 -0400 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F070131ED2 for ; Tue, 18 Oct 2022 01:56:00 -0700 (PDT) Received: by verein.lst.de (Postfix, from userid 2407) id 4246D68C4E; Tue, 18 Oct 2022 10:55:57 +0200 (CEST) Date: Tue, 18 Oct 2022 10:55:57 +0200 From: Christoph Hellwig To: Sagi Grimberg Cc: Christoph Hellwig , Chao Leng , linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, kbusch@kernel.org, ming.lei@redhat.com, axboe@kernel.dk Subject: Re: [PATCH v2 1/2] blk-mq: add tagset quiesce interface Message-ID: <20221018085557.GA28266@lst.de> References: <20221013094450.5947-1-lengchao@huawei.com> <20221013094450.5947-2-lengchao@huawei.com> <20221017133906.GA24492@lst.de> <20221017134244.GA24775@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Tue, Oct 18, 2022 at 11:39:30AM +0300, Sagi Grimberg wrote: > The only question in my mind is regarding patch 2/2 with the subtle > ordering of nvme_set_queue_dying... I think we need to sort that out as a pre-patch. There is quite some history there was a fair amount of dead lock potential earlier, but I think I sorted quite a lot out there, including a new lock for setting the gendisk size, which is what the comment refers to. Something like this: diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c index 059737c1a2c19..cb7623b5d2c8b 100644 --- a/drivers/nvme/host/core.c +++ b/drivers/nvme/host/core.c @@ -5105,21 +5105,21 @@ static void nvme_stop_ns_queue(struct nvme_ns *ns) /* * Prepare a queue for teardown. - * - * This must forcibly unquiesce queues to avoid blocking dispatch, and only set - * the capacity to 0 after that to avoid blocking dispatchers that may be - * holding bd_butex. This will end buffered writers dirtying pages that can't - * be synced. */ static void nvme_set_queue_dying(struct nvme_ns *ns) { if (test_and_set_bit(NVME_NS_DEAD, &ns->flags)) return; + /* + * Mark the disk dead to prevent new opens, and set the capacity to 0 + * to end buffered writers dirtying pages that can't be synced. + */ blk_mark_disk_dead(ns->disk); - nvme_start_ns_queue(ns); - set_capacity_and_notify(ns->disk, 0); + + /* forcibly unquiesce queues to avoid blocking dispatch */ + nvme_start_ns_queue(ns); } /**