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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 B43D1C388F3 for ; Tue, 1 Oct 2019 11:47:18 +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 8896521906 for ; Tue, 1 Oct 2019 11:47:18 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8896521906 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]:40664 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iFGcN-0002mU-VF for qemu-devel@archiver.kernel.org; Tue, 01 Oct 2019 07:47:00 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:34729) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iFGay-0001rg-D4 for qemu-devel@nongnu.org; Tue, 01 Oct 2019 07:45:33 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iFGax-0006CJ-4Y for qemu-devel@nongnu.org; Tue, 01 Oct 2019 07:45:32 -0400 Received: from mx1.redhat.com ([209.132.183.28]:42628) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iFGau-00060G-4h; Tue, 01 Oct 2019 07:45:28 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id C3FC2356CE; Tue, 1 Oct 2019 11:45:20 +0000 (UTC) Received: from angien.pipo.sk (unknown [10.43.2.229]) by smtp.corp.redhat.com (Postfix) with ESMTPS id B88C96012D; Tue, 1 Oct 2019 11:45:16 +0000 (UTC) Date: Tue, 1 Oct 2019 13:45:14 +0200 From: Peter Krempa To: Vladimir Sementsov-Ogievskiy Subject: Re: bitmap migration bug with -drive while block mirror runs Message-ID: <20191001114514.GA9210@angien.pipo.sk> References: <315cff78-dcdb-a3ce-2742-da3cc9f0ca97@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable In-Reply-To: X-PGP-Key-ID: 0xD018682B X-PGP-Key-Fingerprint: D294 FF38 A6A2 BF40 6C75 5DEF 36EC 16AC D018 682B User-Agent: Mutt/1.12.1 (2019-06-15) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Tue, 01 Oct 2019 11:45:20 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.132.183.28 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: John Snow , qemu-devel , Qemu-block , Max Reitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Tue, Oct 01, 2019 at 08:57:37 +0000, Vladimir Sementsov-Ogievskiy wrote: > 01.10.2019 3:09, John Snow wrote: > > Hi folks, I identified a problem with the migration code that Red Hat QE > > found and thought you'd like to see it: > >=20 > > https://bugzilla.redhat.com/show_bug.cgi?id=3D1652424#c20 > >=20 > > Very, very briefly: drive-mirror inserts a filter node that changes what > > bdrv_get_device_or_node_name() returns, which causes a migration proble= m. > >=20 > >=20 > > Ignorant question #1: Can we multi-parent the filter node and > > source-node? It looks like at the moment both consider their only parent > > to be the block-job and don't have a link back to their parents otherwi= se. > >=20 > >=20 > > Otherwise: I have a lot of cloudy ideas on how to solve this, but > > ultimately what we want is to be able to find the "addressable" name for > > the node the bitmap is attached to, which would be the name of the first > > ancestor node that isn't a filter. (OR, the name of the block-backend > > above that node.) >=20 >=20 > Better would be to migrate by node-name only.. But am I right that node-n= ames > are different on source and destination? Or this situation changed? They may be different. Some time ago when I asked I was told that node names are not bound to any state in qemu and thus can be re-created on destination. Otherwise they technically become guest ABI which would require changes to libvirt's blockdev usage.