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 AF584C433E0 for ; Wed, 10 Jun 2020 16:45:56 +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 7AFA0206F4 for ; Wed, 10 Jun 2020 16:45:56 +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="MdZj8DCe" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7AFA0206F4 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]:44024 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jj3rP-0007F1-Nl for qemu-devel@archiver.kernel.org; Wed, 10 Jun 2020 12:45:55 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:42744) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jj3qT-0006ND-KM for qemu-devel@nongnu.org; Wed, 10 Jun 2020 12:44:57 -0400 Received: from us-smtp-1.mimecast.com ([207.211.31.81]:22251 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 1jj3qS-0008Tt-UG for qemu-devel@nongnu.org; Wed, 10 Jun 2020 12:44:57 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1591807496; 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=wB4khYeT5Kk0OngYYHb5SBNKLmkbP50lSa7RRW+B72c=; b=MdZj8DCeZrnqDrPaRAHG219pwqkm9LCRpeFgq2tW5I4Q/ne/o92lDVz8x57Cc17l5tpkaN xO2kbo/YmSDi4iMu2yfhBHyaH82T9cDQjXi4NSSs5tGEsfhisTgJjOFxYjcCzuze7orcwr EVQ3nsj4d/1MW/KtMqntQsGE8xb14bU= 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-305-doLWGNaoOlyuNtlXB4N-mQ-1; Wed, 10 Jun 2020 12:44:52 -0400 X-MC-Unique: doLWGNaoOlyuNtlXB4N-mQ-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 B5B89107ACCD; Wed, 10 Jun 2020 16:44:50 +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 BBBD9891E2; Wed, 10 Jun 2020 16:44:49 +0000 (UTC) Subject: Re: [PATCH v8 30/34] qcow2: Add prealloc field to QCowL2Meta To: Alberto Garcia , qemu-devel@nongnu.org References: <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 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <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; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=207.211.31.81; envelope-from=eblake@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/06/09 23:22:15 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 field allows us to indicate that the L2 metadata update does not > come from a write request with actual data but from a preallocation > request. > > For traditional images this does not make any difference, but for > images with extended L2 entries this means that the clusters are > allocated normally in the L2 table but individual subclusters are > marked as unallocated. > > This will allow preallocating images that have a backing file. > > There is one special case: when we resize an existing image we can > also request that the new clusters are preallocated. If the image > already had a backing file then we have to hide any possible stale > data and zero out the new clusters (see commit 955c7d6687 for more > details). > > In this case the subclusters cannot be left as unallocated so the L2 > bitmap must be updated. > > Signed-off-by: Alberto Garcia > --- Reviewed-by: Eric Blake -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org