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 3128CC432C3 for ; Wed, 20 Nov 2019 14:21:24 +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 EDB592230E for ; Wed, 20 Nov 2019 14:21:23 +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="Pt93TisJ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EDB592230E 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]:58594 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iXQrD-0000Ga-5d for qemu-devel@archiver.kernel.org; Wed, 20 Nov 2019 09:21:23 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:50326) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iXQqT-000898-UF for qemu-devel@nongnu.org; Wed, 20 Nov 2019 09:20:38 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iXQqS-0008G1-8h for qemu-devel@nongnu.org; Wed, 20 Nov 2019 09:20:37 -0500 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:37544 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iXQqR-0008FS-Qt for qemu-devel@nongnu.org; Wed, 20 Nov 2019 09:20:36 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1574259634; 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=C5DsW2oXPcvT0d/fO5GK8Ye21JORfoinsq2i7K+dORE=; b=Pt93TisJbS2EAunAPG5hOGDvoNnTaUuUy0/coh8DY3cRohMIpOsMAVcobbjUOLxXtEPfig QPNgeUrlxegFapMjNmKZKNsUUdMHpARQVjbEBTIbCTZelewU35RcWgtlfwbWGDFrKJ00b6 drAJrbiCKwzBlrZxw2wYx8ZkVGE+1Ig= 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-185-IZpBZDaJOYmWJxbTsjQkow-1; Wed, 20 Nov 2019 09:20:29 -0500 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id E9C0E1883523; Wed, 20 Nov 2019 14:20:27 +0000 (UTC) Received: from [10.3.116.221] (ovpn-116-221.phx2.redhat.com [10.3.116.221]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 6BA995F77B; Wed, 20 Nov 2019 14:20:24 +0000 (UTC) Subject: Re: [PATCH 2/6] block: truncate: Don't make backing file data visible To: Kevin Wolf , qemu-block@nongnu.org References: <20191120140319.1505-1-kwolf@redhat.com> <20191120140319.1505-3-kwolf@redhat.com> From: Eric Blake Organization: Red Hat, Inc. Message-ID: <95e8d68a-94ae-2fff-0c40-44b96d237c2d@redhat.com> Date: Wed, 20 Nov 2019 08:20:23 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.1.1 MIME-Version: 1.0 In-Reply-To: <20191120140319.1505-3-kwolf@redhat.com> Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-MC-Unique: IZpBZDaJOYmWJxbTsjQkow-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 207.211.31.120 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: vsementsov@virtuozzo.com, qemu-devel@nongnu.org, stefanha@redhat.com, mreitz@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 11/20/19 8:03 AM, Kevin Wolf wrote: > When extending the size of an image that has a backing file larger than > its old size, make sure that the backing file data doesn't become > visible in the guest, but the added area is properly zeroed out. >=20 > The old behaviour made a difference in 'block_resize' (where showing the > backing file data from an old snapshot rather than zeros is > questionable) as well as in commit block jobs (both from active and > intermediate nodes) and HMP 'commit', where committing to a short > backing file would incorrectly omit writing zeroes for unallocated > blocks on the top layer after the EOF of the short backing file. >=20 > Signed-off-by: Kevin Wolf > --- > block/io.c | 25 +++++++++++++++++++++++++ > 1 file changed, 25 insertions(+) Reviewed-by: Eric Blake --=20 Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org