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=-3.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 830B0C433E7 for ; Wed, 2 Sep 2020 16:49:35 +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 4DCB020767 for ; Wed, 2 Sep 2020 16:49:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="VszKf4y6" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4DCB020767 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]:60160 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kDVx0-0006X8-GP for qemu-devel@archiver.kernel.org; Wed, 02 Sep 2020 12:49:34 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:41446) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kDVwH-0005DQ-1v for qemu-devel@nongnu.org; Wed, 02 Sep 2020 12:48:49 -0400 Received: from us-smtp-2.mimecast.com ([207.211.31.81]:50008 helo=us-smtp-delivery-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kDVwF-0006qq-3d for qemu-devel@nongnu.org; Wed, 02 Sep 2020 12:48:48 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1599065325; 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: content-transfer-encoding:content-transfer-encoding; bh=tHDKc/REg/30yOgPpdb4g2AK0OfgET4VEn/0qpTHzlk=; b=VszKf4y6BGS5tqNRMqy8PIY4fFjbD/6jALbfierfdHNTFlEnBPu/8hhZ6QcWK1bMfqyF+l evemgTZlLpKaVYbwn+cQk/wVzD8i72IE7pAXmoh8nfdoJsQGvFPldaZJZg/QA3m3A/T98Z BQ8ierZEvQI0268MdT3hsNqNh8Ko1/E= 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-325-kE_uApKNNiaRz5v05pLeYg-1; Wed, 02 Sep 2020 12:48:44 -0400 X-MC-Unique: kE_uApKNNiaRz5v05pLeYg-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 07E77640A2; Wed, 2 Sep 2020 16:48:43 +0000 (UTC) Received: from localhost (ovpn-114-169.ams2.redhat.com [10.36.114.169]) by smtp.corp.redhat.com (Postfix) with ESMTPS id A22785C1D7; Wed, 2 Sep 2020 16:48:42 +0000 (UTC) From: Max Reitz To: qemu-block@nongnu.org Subject: [PATCH 0/3] mirror: Freeze backing chain for sync=top Date: Wed, 2 Sep 2020 18:48:38 +0200 Message-Id: <20200902164841.214948-1-mreitz@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=mreitz@redhat.com X-Mimecast-Spam-Score: 0.001 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=207.211.31.81; envelope-from=mreitz@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/09/02 02:33:32 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action 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: Kevin Wolf , John Snow , qemu-devel@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Hi, On review of the “Deal with filters” series, Kevin noted that mirror doesn’t freeze its backing chain, even though we keep references to the base (for sync=top). That seems like a recipe for disaster, and as the test added in patch 3 shows, indeed it is. Patch 1 could also be squashed into “mirror: Deal with filters”. As for patch 2; maybe it would be sufficient to freeze the backing chain only down to base_overlay and until mirror_dirty_init() is done. Then we bdrv_ref(s->base) so can always be attached to the target when mirror completes. But I think the conservative approach I implemented here is fine until someone complains. Max Reitz (3): mirror: Set s->base_overlay only if s->base is set mirror: Freeze backing chain for sync=top iotests/041: x-blockdev-reopen during mirror block/mirror.c | 28 +++++++++--- tests/qemu-iotests/041 | 92 ++++++++++++++++++++++++++++++++++++++ tests/qemu-iotests/041.out | 4 +- 3 files changed, 116 insertions(+), 8 deletions(-) -- 2.26.2