[{"id":2456154,"web_url":"http://patchwork.ozlabs.org/comment/2456154/","msgid":"","list_archive_url":null,"date":"2020-06-10T16:44:49","subject":"Re: [PATCH v8 30/34] qcow2: Add prealloc field to QCowL2Meta","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 field allows us to indicate that the L2 metadata update does not\n> come from a write request with actual data but from a preallocation\n> request.\n> \n> For traditional images this does not make any difference, but for\n> images with extended L2 entries this means that the clusters are\n> allocated normally in the L2 table but individual subclusters are\n> marked as unallocated.\n> \n> This will allow preallocating images that have a backing file.\n> \n> There is one special case: when we resize an existing image we can\n> also request that the new clusters are preallocated. If the image\n> already had a backing file then we have to hide any possible stale\n> data and zero out the new clusters (see commit 955c7d6687 for more\n> details).\n> \n> In this case the subclusters cannot be left as unallocated so the L2\n> bitmap must be updated.\n> \n> Signed-off-by: Alberto Garcia \n> ---\n\nReviewed-by: Eric Blake ","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=MdZj8DCe;\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 49htCM20gqz9sRR\n\tfor ; Thu, 11 Jun 2020 02:45:33 +1000 (AEST)","from localhost ([::1]:42288 helo=lists1p.gnu.org)\n\tby lists.gnu.org with esmtp (Exim 4.90_1)\n\t(envelope-from )\n\tid 1jj3r0-0006OP-4j\n\tfor incoming@patchwork.ozlabs.org; Wed, 10 Jun 2020 12:45:30 -0400","from eggs.gnu.org ([2001:470:142:3::10]:42744)\n by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256)\n (Exim 4.90_1) (envelope-from ) id 1jj3qT-0006ND-KM\n for qemu-devel@nongnu.org; Wed, 10 Jun 2020 12:44:57 -0400","from us-smtp-1.mimecast.com ([207.211.31.81]:22251\n helo=us-smtp-delivery-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 1jj3qS-0008Tt-UG\n for qemu-devel@nongnu.org; Wed, 10 Jun 2020 12:44:57 -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-305-doLWGNaoOlyuNtlXB4N-mQ-1; Wed, 10 Jun 2020 12:44:52 -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 B5B89107ACCD;\n Wed, 10 Jun 2020 16:44:50 +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 BBBD9891E2;\n Wed, 10 Jun 2020 16:44:49 +0000 (UTC)"],"DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com;\n s=mimecast20190719; t=1591807496;\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=wB4khYeT5Kk0OngYYHb5SBNKLmkbP50lSa7RRW+B72c=;\n b=MdZj8DCeZrnqDrPaRAHG219pwqkm9LCRpeFgq2tW5I4Q/ne/o92lDVz8x57Cc17l5tpkaN\n xO2kbo/YmSDi4iMu2yfhBHyaH82T9cDQjXi4NSSs5tGEsfhisTgJjOFxYjcCzuze7orcwr\n EVQ3nsj4d/1MW/KtMqntQsGE8xb14bU=","X-MC-Unique":"doLWGNaoOlyuNtlXB4N-mQ-1","Subject":"Re: [PATCH v8 30/34] qcow2: Add prealloc field to QCowL2Meta","To":"Alberto Garcia , qemu-devel@nongnu.org","References":"\n <259e53cff2911316e427c40001801004e6b4257d.1591801197.git.berto@igalia.com>","From":"Eric Blake ","Organization":"Red Hat, Inc.","Message-ID":"","Date":"Wed, 10 Jun 2020 11:44:49 -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 <259e53cff2911316e427c40001801004e6b4257d.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; 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