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=-5.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,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 A9F45C433E0 for ; Wed, 10 Jun 2020 19:44:49 +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 77D97206F7 for ; Wed, 10 Jun 2020 19:44:49 +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="GiJ/Svw8" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 77D97206F7 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]:59044 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jj6eW-00037t-D5 for qemu-devel@archiver.kernel.org; Wed, 10 Jun 2020 15:44:48 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:36704) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jj6dr-0002bz-3i for qemu-devel@nongnu.org; Wed, 10 Jun 2020 15:44:07 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:46661 helo=us-smtp-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 1jj6dq-0005Oh-57 for qemu-devel@nongnu.org; Wed, 10 Jun 2020 15:44:06 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1591818245; 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: in-reply-to:in-reply-to:references:references; bh=xnjZZRG0wkflNR1WORyD8Iy6jpm5Iq6gcwaR4msTDFw=; b=GiJ/Svw8OjHMERbgwI/GCCJaSArjSgYNTGWuxRNabYFQy4fHfyXB+QVK+9ubQdW2nhbBMg IZ9bnYlbGbQjx3y9IxMZgBAj9VLTq97h49AE1i/2phyq7kIIK4n8/NBZn0QLA+stVxPfOa PFAvodPzU0JvArk7upjJG1ZygGNPOh0= 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-102-8U1o5u8vOKGvqFNUwGvJiA-1; Wed, 10 Jun 2020 15:44:03 -0400 X-MC-Unique: 8U1o5u8vOKGvqFNUwGvJiA-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 1AD4D108BD09; Wed, 10 Jun 2020 19:44:02 +0000 (UTC) Received: from [10.3.113.22] (ovpn-113-22.phx2.redhat.com [10.3.113.22]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 4AD8D7CCF0; Wed, 10 Jun 2020 19:43:56 +0000 (UTC) Subject: Re: [PATCH v8 33/34] qcow2: Assert that expand_zero_clusters_in_l1() does not support subclusters To: Alberto Garcia , qemu-devel@nongnu.org References: <19afb93b267b9698edf5e0253458c5db69ef91a2.1591801197.git.berto@igalia.com> From: Eric Blake Organization: Red Hat, Inc. Message-ID: Date: Wed, 10 Jun 2020 14:43:53 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <19afb93b267b9698edf5e0253458c5db69ef91a2.1591801197.git.berto@igalia.com> Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=205.139.110.120; envelope-from=eblake@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/06/10 15:44:05 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, 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_H4=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=_AUTOLEARN 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 , Derek Su , Vladimir Sementsov-Ogievskiy , qemu-block@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 6/10/20 10:03 AM, Alberto Garcia wrote: > This function is only used by qcow2_expand_zero_clusters() to > downgrade a qcow2 image to a previous version. It is however not > possible to downgrade an image with extended L2 entries because older > versions of qcow2 do not have this feature. Well, it _is_ possible, but it would involve rewriting the entire L1/L2 tables (including all internal snapshots), as well as causing I/O to COW every cluster where not all subclusters are allocated; and doing that conversion while remaining crash-consistent requires some thought and a temporary extra load on disk space (we can't discard the old table until the new one is completely written). It would be more accurate to merely state that we are not prepared to implement it at this time. > > Signed-off-by: Alberto Garcia > Reviewed-by: Eric Blake > --- > block/qcow2-cluster.c | 8 +++++++- > tests/qemu-iotests/061 | 6 ++++++ > tests/qemu-iotests/061.out | 5 +++++ > 3 files changed, 18 insertions(+), 1 deletion(-) > Whether or not we update the commit message, R-b stands for the code. -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org