[{"id":2456278,"web_url":"http://patchwork.ozlabs.org/comment/2456278/","msgid":"","list_archive_url":null,"date":"2020-06-10T19:43:53","subject":"Re: [PATCH v8 33/34] qcow2: Assert that expand_zero_clusters_in_l1()\n does not support subclusters","submitter":{"id":6591,"url":"http://patchwork.ozlabs.org/api/people/6591/","name":"Eric Blake","email":"eblake@redhat.com"},"content":"On 6/10/20 10:03 AM, Alberto Garcia wrote:\n> This function is only used by qcow2_expand_zero_clusters() to\n> downgrade a qcow2 image to a previous version. It is however not\n> possible to downgrade an image with extended L2 entries because older\n> versions of qcow2 do not have this feature.\n\nWell, it _is_ possible, but it would involve rewriting the entire L1/L2 \ntables (including all internal snapshots), as well as causing I/O to COW \nevery cluster where not all subclusters are allocated; and doing that \nconversion while remaining crash-consistent requires some thought and a \ntemporary extra load on disk space (we can't discard the old table until \nthe new one is completely written).\n\nIt would be more accurate to merely state that we are not prepared to \nimplement it at this time.\n\n> \n> Signed-off-by: Alberto Garcia \n> Reviewed-by: Eric Blake \n> ---\n> block/qcow2-cluster.c | 8 +++++++-\n> tests/qemu-iotests/061 | 6 ++++++\n> tests/qemu-iotests/061.out | 5 +++++\n> 3 files changed, 18 insertions(+), 1 deletion(-)\n> \n\nWhether or not we update the commit message, R-b stands for the code.","headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@bilbo.ozlabs.org","Authentication-Results":["ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org\n (client-ip=209.51.188.17; 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Wed, 10 Jun 2020 15:44:07 -0400","from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:46661\n helo=us-smtp-1.mimecast.com)\n by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256)\n (Exim 4.90_1) (envelope-from ) id 1jj6dq-0005Oh-57\n for qemu-devel@nongnu.org; Wed, 10 Jun 2020 15:44:06 -0400","from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com\n [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id\n us-mta-102-8U1o5u8vOKGvqFNUwGvJiA-1; Wed, 10 Jun 2020 15:44:03 -0400","from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com\n [10.5.11.13])\n (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits))\n (No client certificate requested)\n by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 1AD4D108BD09;\n Wed, 10 Jun 2020 19:44:02 +0000 (UTC)","from [10.3.113.22] (ovpn-113-22.phx2.redhat.com [10.3.113.22])\n by smtp.corp.redhat.com (Postfix) with ESMTPS id 4AD8D7CCF0;\n Wed, 10 Jun 2020 19:43:56 +0000 (UTC)"],"DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com;\n s=mimecast20190719; t=1591818245;\n h=from:from:reply-to:subject:subject:date:date:message-id:message-id:\n to:to:cc:cc:mime-version:mime-version:content-type:content-type:\n content-transfer-encoding:content-transfer-encoding:\n in-reply-to:in-reply-to:references:references;\n bh=xnjZZRG0wkflNR1WORyD8Iy6jpm5Iq6gcwaR4msTDFw=;\n b=GiJ/Svw8OjHMERbgwI/GCCJaSArjSgYNTGWuxRNabYFQy4fHfyXB+QVK+9ubQdW2nhbBMg\n IZ9bnYlbGbQjx3y9IxMZgBAj9VLTq97h49AE1i/2phyq7kIIK4n8/NBZn0QLA+stVxPfOa\n PFAvodPzU0JvArk7upjJG1ZygGNPOh0=","X-MC-Unique":"8U1o5u8vOKGvqFNUwGvJiA-1","Subject":"Re: [PATCH v8 33/34] qcow2: Assert that expand_zero_clusters_in_l1()\n does not support subclusters","To":"Alberto Garcia , qemu-devel@nongnu.org","References":"\n <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\n Thunderbird/68.8.0","MIME-Version":"1.0","In-Reply-To":"\n <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;\n 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,\n DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1,\n RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=-0.01, RCVD_IN_MSPIKE_WL=-0.01,\n 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":",\n ","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n ","Cc":"Kevin Wolf , Derek Su ,\n Vladimir Sementsov-Ogievskiy ,\n qemu-block@nongnu.org,\n Max Reitz ","Errors-To":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org","Sender":"\"Qemu-devel\"\n "}},{"id":2456779,"web_url":"http://patchwork.ozlabs.org/comment/2456779/","msgid":"","list_archive_url":null,"date":"2020-06-11T13:24:30","subject":"Re: [PATCH v8 33/34] qcow2: Assert that expand_zero_clusters_in_l1()\n does not support subclusters","submitter":{"id":65704,"url":"http://patchwork.ozlabs.org/api/people/65704/","name":"Alberto Garcia","email":"berto@igalia.com"},"content":"On Wed 10 Jun 2020 09:43:53 PM CEST, Eric Blake wrote:\n> On 6/10/20 10:03 AM, Alberto Garcia wrote:\n>> This function is only used by qcow2_expand_zero_clusters() to\n>> downgrade a qcow2 image to a previous version. It is however not\n>> possible to downgrade an image with extended L2 entries because older\n>> versions of qcow2 do not have this feature.\n>\n> Well, it _is_ possible, but it would involve rewriting the entire\n> L1/L2 tables (including all internal snapshots)\n\nRight :-) Let's try this way:\n\n This function is only used by qcow2_expand_zero_clusters() to\n downgrade a qcow2 image to a previous version. This would require\n transforming all extended L2 entries into normal L2 entries but\n this is not a simple task and there are no plans to implement this\n at the moment.\n\nBerto","headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@bilbo.ozlabs.org","Authentication-Results":["ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org\n (client-ip=209.51.188.17; helo=lists.gnu.org;\n envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org;\n receiver=)","ozlabs.org;\n dmarc=none (p=none dis=none) header.from=igalia.com","ozlabs.org;\n\tdkim=fail reason=\"signature verification failed\" (2048-bit key;\n unprotected) header.d=igalia.com header.i=@igalia.com header.a=rsa-sha256\n header.s=20170329 header.b=Chi9BmGi;\n\tdkim-atps=neutral"],"Received":["from lists.gnu.org (lists.gnu.org [209.51.188.17])\n\t(using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))\n\t(No client certificate requested)\n\tby ozlabs.org (Postfix) with ESMTPS id 49jPk80td6z9sQx\n\tfor ; Thu, 11 Jun 2020 23:25:36 +1000 (AEST)","from localhost ([::1]:40888 helo=lists1p.gnu.org)\n\tby lists.gnu.org with esmtp (Exim 4.90_1)\n\t(envelope-from )\n\tid 1jjND3-0003SH-KE\n\tfor incoming@patchwork.ozlabs.org; Thu, 11 Jun 2020 09:25:33 -0400","from eggs.gnu.org ([2001:470:142:3::10]:34420)\n by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256)\n (Exim 4.90_1) (envelope-from )\n id 1jjNCT-0003PM-5f; Thu, 11 Jun 2020 09:24:57 -0400","from fanzine.igalia.com ([178.60.130.6]:54281)\n by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128)\n (Exim 4.90_1) (envelope-from )\n id 1jjNCR-0000Mz-Ho; Thu, 11 Jun 2020 09:24:56 -0400","from maestria.local.igalia.com ([192.168.10.14]\n helo=mail.igalia.com)\n by fanzine.igalia.com with esmtps\n (Cipher TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim)\n id 1jjNC2-00061n-Ru; Thu, 11 Jun 2020 15:24:30 +0200","from berto by mail.igalia.com with local (Exim)\n id 1jjNC2-0006sE-Hj; Thu, 11 Jun 2020 15:24:30 +0200"],"DKIM-Signature":"v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com;\n s=20170329;\n h=Content-Type:MIME-Version:Message-ID:Date:References:In-Reply-To:Subject:Cc:To:From;\n bh=TbGuVxNClVfyTAUvLHlpJV0TvM5BxgfRDVj0lAWDjZo=;\n b=Chi9BmGi0idvpgfzsClghcy+VfTB2acQz1wt+33nt+GGAexQBKs4PKzciLZy/VOXvk8AOyeqXl3kWZwKlLBYQECLKl1/ebbDIrRWqxP4WWIzQR3h2LuiWW20/hyuub+goKQ7yD9Us6ESV66TAjX+Yz1OC33g1l4ZLcOflDhXk1lrZISvNdRpoLrlAq4Ip3NpF58ZGLg4881jbhesN0RCS3Necj4LRysbD0vdC643ctEosDk0vQJBHACYScADVOYYQObLBaq1RdgV/vTgOqI9Pf8T/eGLHmx+zcdOG3ztdrYOo1pm+aKQPjjL3A/EWAMiCuNqbM7JbMzZJP+pIKS1Bg==;","From":"Alberto Garcia ","To":"Eric Blake , qemu-devel@nongnu.org","Subject":"Re: [PATCH v8 33/34] qcow2: Assert that expand_zero_clusters_in_l1()\n does not support subclusters","In-Reply-To":"","References":"\n <19afb93b267b9698edf5e0253458c5db69ef91a2.1591801197.git.berto@igalia.com>\n ","User-Agent":"Notmuch/0.18.2 (http://notmuchmail.org) Emacs/24.4.1\n (i586-pc-linux-gnu)","Date":"Thu, 11 Jun 2020 15:24:30 +0200","Message-ID":"","MIME-Version":"1.0","Content-Type":"text/plain","Received-SPF":"pass client-ip=178.60.130.6; envelope-from=berto@igalia.com;\n helo=fanzine.igalia.com","X-detected-operating-system":"by eggs.gnu.org: First seen = 2020/06/11 09:24:32","X-ACL-Warn":"Detected OS = Linux 2.2.x-3.x (no timestamps) [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, DKIM_SIGNED=0.1,\n DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, SPF_HELO_NONE=0.001,\n SPF_PASS=-0.001, URIBL_BLOCKED=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":",\n ","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n ","Cc":"Kevin Wolf , Derek Su ,\n Vladimir Sementsov-Ogievskiy ,\n qemu-block@nongnu.org,\n Max Reitz ","Errors-To":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org","Sender":"\"Qemu-devel\"\n "}},{"id":2456820,"web_url":"http://patchwork.ozlabs.org/comment/2456820/","msgid":"<033a2dc9-6dbf-dca8-9963-84f0a374e907@redhat.com>","list_archive_url":null,"date":"2020-06-11T14:36:48","subject":"Re: [PATCH v8 33/34] qcow2: Assert that expand_zero_clusters_in_l1()\n does not support subclusters","submitter":{"id":6591,"url":"http://patchwork.ozlabs.org/api/people/6591/","name":"Eric Blake","email":"eblake@redhat.com"},"content":"On 6/11/20 8:24 AM, Alberto Garcia wrote:\n> On Wed 10 Jun 2020 09:43:53 PM CEST, Eric Blake wrote:\n>> On 6/10/20 10:03 AM, Alberto Garcia wrote:\n>>> This function is only used by qcow2_expand_zero_clusters() to\n>>> downgrade a qcow2 image to a previous version. It is however not\n>>> possible to downgrade an image with extended L2 entries because older\n>>> versions of qcow2 do not have this feature.\n>>\n>> Well, it _is_ possible, but it would involve rewriting the entire\n>> L1/L2 tables (including all internal snapshots)\n> \n> Right :-) Let's try this way:\n> \n> This function is only used by qcow2_expand_zero_clusters() to\n> downgrade a qcow2 image to a previous version. This would require\n> transforming all extended L2 entries into normal L2 entries but\n> this is not a simple task and there are no plans to implement this\n> at the moment.\n\nWorks for me.","headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@bilbo.ozlabs.org","Authentication-Results":["ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org\n (client-ip=209.51.188.17; helo=lists.gnu.org;\n envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org;\n receiver=)","ozlabs.org;\n dmarc=fail (p=none dis=none) header.from=redhat.com","ozlabs.org;\n\tdkim=fail reason=\"signature verification failed\" (1024-bit key;\n unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256\n header.s=mimecast20190719 header.b=A7V5c6jb;\n\tdkim-atps=neutral"],"Received":["from lists.gnu.org (lists.gnu.org [209.51.188.17])\n\t(using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))\n\t(No client certificate requested)\n\tby ozlabs.org (Postfix) with ESMTPS id 49jRJy5mFzz9sR4\n\tfor ; Fri, 12 Jun 2020 00:37:22 +1000 (AEST)","from localhost ([::1]:43216 helo=lists1p.gnu.org)\n\tby lists.gnu.org with esmtp (Exim 4.90_1)\n\t(envelope-from )\n\tid 1jjOKW-0004U2-HW\n\tfor incoming@patchwork.ozlabs.org; Thu, 11 Jun 2020 10:37:20 -0400","from eggs.gnu.org ([2001:470:142:3::10]:37636)\n by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256)\n (Exim 4.90_1) (envelope-from ) id 1jjOK7-0004SM-WE\n for qemu-devel@nongnu.org; Thu, 11 Jun 2020 10:36:56 -0400","from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:57482\n helo=us-smtp-1.mimecast.com)\n by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256)\n (Exim 4.90_1) (envelope-from ) id 1jjOK6-0001vQ-9y\n for qemu-devel@nongnu.org; Thu, 11 Jun 2020 10:36:55 -0400","from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com\n [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id\n us-mta-169-vDfpWE7aPmKNghQaMSfkwA-1; Thu, 11 Jun 2020 10:36:51 -0400","from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com\n [10.5.11.13])\n (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits))\n (No client certificate requested)\n by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 4A3BA18A8220;\n Thu, 11 Jun 2020 14:36:50 +0000 (UTC)","from [10.3.113.22] (ovpn-113-22.phx2.redhat.com [10.3.113.22])\n by smtp.corp.redhat.com (Postfix) with ESMTPS id BA0A18FF81;\n Thu, 11 Jun 2020 14:36:48 +0000 (UTC)"],"DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com;\n s=mimecast20190719; t=1591886213;\n h=from:from:reply-to:subject:subject:date:date:message-id:message-id:\n to:to:cc:cc:mime-version:mime-version:content-type:content-type:\n content-transfer-encoding:content-transfer-encoding:\n in-reply-to:in-reply-to:references:references;\n bh=R8iGEVR1kQQwsgaN0ZpVmjwYHpEbDiFbdqFaOwDYgTE=;\n b=A7V5c6jbX5uY/Dv4kSTlbl6tuZ/Gg5kT6T4tvdetLMucdTc/OnH+QB1ubX8IsAMvvtWwsr\n DinDSRO951pb6F8QE/yr/U3urvo+uBcL+0ktEuehlXoeN6eUB7d77Dy867lUs+MPbBnAUY\n 0RxE/pON8Il8HG3iHHahYAB3yxyA3iE=","X-MC-Unique":"vDfpWE7aPmKNghQaMSfkwA-1","Subject":"Re: [PATCH v8 33/34] qcow2: Assert that expand_zero_clusters_in_l1()\n does not support subclusters","To":"Alberto Garcia , qemu-devel@nongnu.org","References":"\n <19afb93b267b9698edf5e0253458c5db69ef91a2.1591801197.git.berto@igalia.com>\n \n ","From":"Eric Blake ","Organization":"Red Hat, Inc.","Message-ID":"<033a2dc9-6dbf-dca8-9963-84f0a374e907@redhat.com>","Date":"Thu, 11 Jun 2020 09:36:48 -0500","User-Agent":"Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101\n Thunderbird/68.8.0","MIME-Version":"1.0","In-Reply-To":"","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=207.211.31.120; envelope-from=eblake@redhat.com;\n helo=us-smtp-1.mimecast.com","X-detected-operating-system":"by eggs.gnu.org: First seen = 2020/06/11 08:37:10","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,\n DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1,\n RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01,\n 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":",\n ","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n ","Cc":"Kevin Wolf , Derek Su ,\n Vladimir Sementsov-Ogievskiy ,\n qemu-block@nongnu.org,\n Max Reitz ","Errors-To":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org","Sender":"\"Qemu-devel\"\n "}}]