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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 3D518C4332F for ; Tue, 18 Oct 2022 08:56:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=V1i+ZQl4Y4THZO210D0hR+zLW8ivaq+kCbavH2jLggc=; b=KqVaiEw+n653SgMuK4+NFYnKHk eA3mlSRJWT80mDY+qWG11mxYURzAE0ZEqLBcASwQV94Gc5aS0wR6nNS+PkUgxGCeGhDTwQZpSbi78 NbfqHjRn5VVJHaGYX7vHeALpLbfvt2iZLR4VwQplO82ChBWumIA7pnHaQqdC3ENcBkeJeeRw1K4qj yniqIl2p5pbVBno/Eat7c49TpzHohSukx/YgwB+CIawIFQqEL4z5cj9GVvLACD62A4iIEmrTjFbov lz0mLeN10vPxXI4aFlqs1OURj0EFl+qOpKtManLd0of5enU02zayHu1PKKCeYYpttWkSXrOQATpG7 NHbRIh7A==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1okiOO-004YoR-OB; Tue, 18 Oct 2022 08:56:08 +0000 Received: from verein.lst.de ([213.95.11.211]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1okiOL-004YiO-5g for linux-nvme@lists.infradead.org; Tue, 18 Oct 2022 08:56:08 +0000 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) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221018_015605_414025_5DAD548C X-CRM114-Status: GOOD ( 17.24 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.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); } /**