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=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 00BD5C49ED7 for ; Mon, 16 Sep 2019 07:54:12 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id CB2BC20650 for ; Mon, 16 Sep 2019 07:54:11 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CB2BC20650 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:59618 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i9lpq-0002St-W0 for qemu-devel@archiver.kernel.org; Mon, 16 Sep 2019 03:54:11 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:53727) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i9lp4-0001zp-M1 for qemu-devel@nongnu.org; Mon, 16 Sep 2019 03:53:23 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1i9lp3-0003Tc-IZ for qemu-devel@nongnu.org; Mon, 16 Sep 2019 03:53:22 -0400 Received: from mx1.redhat.com ([209.132.183.28]:33490) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1i9lp1-0003SE-GQ; Mon, 16 Sep 2019 03:53:19 -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 0783A4E926; Mon, 16 Sep 2019 07:53:18 +0000 (UTC) Received: from localhost.localdomain (ovpn-116-251.ams2.redhat.com [10.36.116.251]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 2A25A5D6B2; Mon, 16 Sep 2019 07:53:04 +0000 (UTC) Date: Mon, 16 Sep 2019 09:53:03 +0200 From: Kevin Wolf To: John Snow Message-ID: <20190916075303.GA10930@localhost.localdomain> References: <20190913152507.56197-1-slp@redhat.com> <20190913152507.56197-2-slp@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.12.1 (2019-06-15) 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 [10.5.110.38]); Mon, 16 Sep 2019 07:53:18 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [Qemu-block] [PATCH v2 1/2] blockdev: release the AioContext at drive_backup_prepare X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: qemu-devel@nongnu.org, mreitz@redhat.com, qemu-block@nongnu.org, Sergio Lopez , armbru@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Am 13.09.2019 um 21:54 hat John Snow geschrieben: > > > On 9/13/19 11:25 AM, Sergio Lopez wrote: > > do_drive_backup() already acquires the AioContext, so release it > > before the call. > > > > Signed-off-by: Sergio Lopez > > --- > > blockdev.c | 6 +----- > > 1 file changed, 1 insertion(+), 5 deletions(-) > > > > diff --git a/blockdev.c b/blockdev.c > > index fbef6845c8..3927fdab80 100644 > > --- a/blockdev.c > > +++ b/blockdev.c > > @@ -1783,20 +1783,16 @@ static void drive_backup_prepare(BlkActionState *common, Error **errp) > > > > aio_context = bdrv_get_aio_context(bs); > > aio_context_acquire(aio_context); > > - Are you removing this unrelated empty line intentionally? > > /* Paired with .clean() */ > > bdrv_drained_begin(bs); > > Do we need to make this change to blockdev_backup_prepare as well? Actually, the whole structure feels a bit wrong. We get the bs here and take its lock, then release the lock again and forget the reference, only to do both things again inside do_drive_backup(). The way snapshots work is that the "normal" snapshot commands are wrappers that turn it into a single-entry transaction. Then you have only one code path where you can resolve the ID and take the lock just once. So maybe backup should work like this, too? Kevin