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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 109B8C433EF for ; Wed, 10 Nov 2021 09:29:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E63C661207 for ; Wed, 10 Nov 2021 09:29:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229781AbhKJJcl (ORCPT ); Wed, 10 Nov 2021 04:32:41 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:42251 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230043AbhKJJck (ORCPT ); Wed, 10 Nov 2021 04:32:40 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1636536592; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=oarUMsE+yLHYJ5q9sN/Q6TTYzT0GV/hjLx4CUDud2S0=; b=OoQOqnlsbkNhsf8D8b8e6m7iUPcOx0ye4wEoC9oW3ObC3dAlTGVwifgVw+az8h993fsYQH zhrvSdja89DHTIhqgBPusYJve4+F+6JSTuayElNexgtZaU5UpDuOxFGJyntnEKIx0Z2WhK VT4gUJPSX+bjybWZaX3C1XoawlshC6w= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-220-xoD12RhyOSCKeWJsjuROZA-1; Wed, 10 Nov 2021 04:29:47 -0500 X-MC-Unique: xoD12RhyOSCKeWJsjuROZA-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 59E2F804147; Wed, 10 Nov 2021 09:29:46 +0000 (UTC) Received: from T590 (ovpn-8-19.pek2.redhat.com [10.72.8.19]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 384F860C05; Wed, 10 Nov 2021 09:29:31 +0000 (UTC) Date: Wed, 10 Nov 2021 17:29:26 +0800 From: Ming Lei To: Christoph Hellwig Cc: Jens Axboe , linux-block@vger.kernel.org, linux-scsi@vger.kernel.org, linux-nvme@lists.infradead.org Subject: Re: sorting out the freeze / quiesce mess Message-ID: References: <20211110091407.GA8396@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211110091407.GA8396@lst.de> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Wed, Nov 10, 2021 at 10:14:07AM +0100, Christoph Hellwig wrote: > Hi Jens and Ming, > > I've been looking into properly supporting queue freezing for bio based > drivers (that is only release q_usage_counter on bio completion for them). > And the deeper I look into the code the more I'm confused by us having > the blk_mq_quiesce* interface in addition to blk_freeze_queue. What > is a good reason to do a quiesce separately from a freeze? freeze can make sure that all requests are done, quiesce can make sure that dispatch critical area(covered by hctx lock/unlock) is done. Thanks, Ming