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=-5.4 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 D3FF7C004C9 for ; Tue, 7 May 2019 08:54:09 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id A08FD204FD for ; Tue, 7 May 2019 08:54:09 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A08FD204FD 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 ([127.0.0.1]:42541 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hNvrU-00029V-QO for qemu-devel@archiver.kernel.org; Tue, 07 May 2019 04:54:08 -0400 Received: from eggs.gnu.org ([209.51.188.92]:36599) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hNvnz-0008V6-0s for qemu-devel@nongnu.org; Tue, 07 May 2019 04:50:32 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hNvny-00021r-07 for qemu-devel@nongnu.org; Tue, 07 May 2019 04:50:30 -0400 Received: from mx1.redhat.com ([209.132.183.28]:3698) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hNvnv-0001yH-Qf; Tue, 07 May 2019 04:50:27 -0400 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 2365130842A0; Tue, 7 May 2019 08:50:27 +0000 (UTC) Received: from localhost.localdomain (ovpn-116-186.ams2.redhat.com [10.36.116.186]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 56C734123; Tue, 7 May 2019 08:50:23 +0000 (UTC) Date: Tue, 7 May 2019 10:50:21 +0200 From: Kevin Wolf To: John Snow Message-ID: <20190507085021.GB5808@localhost.localdomain> References: <20190506203344.30781-1-jsnow@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190506203344.30781-1-jsnow@redhat.com> User-Agent: Mutt/1.11.3 (2019-02-01) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.40]); Tue, 07 May 2019 08:50:27 +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] [PATCH] blockdev-backup: don't check aio_context too early X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: aihua liang , qemu-block@nongnu.org, qemu-devel@nongnu.org, qemu-stable@nongnu.org, Markus Armbruster , Max Reitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Am 06.05.2019 um 22:33 hat John Snow geschrieben: > in blockdev_backup_prepare, we check to make sure that the target is > associated with a compatible aio context. However, do_blockdev_backup is > called later and has some logic to move the target to a compatible > aio_context. The transaction version will fail certain commands > needlessly early as a result. > > Allow blockdev_backup_prepare to simply call do_blockdev_backup, which > will ultimately decide if the contexts are compatible or not. > > Note: the transaction version has always disallowed this operation since > its initial commit bd8baecd (2014), whereas the version of > qmp_blockdev_backup at the time, from commit c29c1dd312f, tried to > enforce the aio_context switch instead. It's not clear, and I can't see > from the mailing list archives at the time, why the two functions take a > different approach. It wasn't until later in efd7556708b (2016) that the > standalone version tried to determine if it could set the context or > not. > > Reported-by: aihua liang > Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1683498 Signed-off-by is missing, and a testcase, too. :-) > diff --git a/blockdev.c b/blockdev.c > index 79fbac8450..a81d88980c 100644 > --- a/blockdev.c > +++ b/blockdev.c > @@ -1872,10 +1872,6 @@ static void blockdev_backup_prepare(BlkActionState *common, Error **errp) > } > > aio_context = bdrv_get_aio_context(bs); > - if (aio_context != bdrv_get_aio_context(target)) { > - error_setg(errp, "Backup between two IO threads is not implemented"); > - return; > - } > aio_context_acquire(aio_context); > state->bs = bs; The actual change looks good to me. Kevin