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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 7C2BDC7618B for ; Thu, 25 Jul 2019 15:30:36 +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 5499421951 for ; Thu, 25 Jul 2019 15:30:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5499421951 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]:32930 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hqfhT-00086J-G6 for qemu-devel@archiver.kernel.org; Thu, 25 Jul 2019 11:30:35 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:48677) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hqfhG-0007Rd-3E for qemu-devel@nongnu.org; Thu, 25 Jul 2019 11:30:23 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hqfhE-0001OR-AE for qemu-devel@nongnu.org; Thu, 25 Jul 2019 11:30:21 -0400 Received: from mx1.redhat.com ([209.132.183.28]:60728) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hqfhA-0001Lg-4u; Thu, 25 Jul 2019 11:30:16 -0400 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 mx1.redhat.com (Postfix) with ESMTPS id 052194628B; Thu, 25 Jul 2019 15:30:15 +0000 (UTC) Received: from maximlenovopc.usersys.redhat.com (unknown [10.35.206.87]) by smtp.corp.redhat.com (Postfix) with ESMTP id 9204C60852; Thu, 25 Jul 2019 15:30:13 +0000 (UTC) Message-ID: From: Maxim Levitsky To: Max Reitz , qemu-block@nongnu.org Date: Thu, 25 Jul 2019 18:30:12 +0300 In-Reply-To: <20190724171239.8764-9-mreitz@redhat.com> References: <20190724171239.8764-1-mreitz@redhat.com> <20190724171239.8764-9-mreitz@redhat.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Thu, 25 Jul 2019 15:30:15 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [PATCH v2 08/11] vhdx: Fix .bdrv_has_zero_init() 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 , qemu-devel@nongnu.org, Stefano Garzarella Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, 2019-07-24 at 19:12 +0200, Max Reitz wrote: > Fixed VHDX images cannot guarantee to be zero-initialized. If the image > has the "fixed" subformat, forward the call to the underlying storage > node. > > Reported-by: Stefano Garzarella > Signed-off-by: Max Reitz > --- > block/vhdx.c | 26 +++++++++++++++++++++++++- > 1 file changed, 25 insertions(+), 1 deletion(-) > > diff --git a/block/vhdx.c b/block/vhdx.c > index a02d1c99a7..6a09d0a55c 100644 > --- a/block/vhdx.c > +++ b/block/vhdx.c > @@ -2075,6 +2075,30 @@ static int coroutine_fn vhdx_co_check(BlockDriverState *bs, > return 0; > } > > +static int vhdx_has_zero_init(BlockDriverState *bs) > +{ > + BDRVVHDXState *s = bs->opaque; > + int state; > + > + /* > + * Check the subformat: Fixed images have all BAT entries present, > + * dynamic images have none (right after creation). It is > + * therefore enough to check the first BAT entry. > + */ > + if (!s->bat_entries) { > + return 1; > + } > + > + state = s->bat[0] & VHDX_BAT_STATE_BIT_MASK; > + if (state == PAYLOAD_BLOCK_FULLY_PRESENT) { > + /* Fixed subformat */ > + return bdrv_has_zero_init(bs->file->bs); > + } > + > + /* Dynamic subformat */ > + return 1; > +} > + > static QemuOptsList vhdx_create_opts = { > .name = "vhdx-create-opts", > .head = QTAILQ_HEAD_INITIALIZER(vhdx_create_opts.head), > @@ -2128,7 +2152,7 @@ static BlockDriver bdrv_vhdx = { > .bdrv_co_create_opts = vhdx_co_create_opts, > .bdrv_get_info = vhdx_get_info, > .bdrv_co_check = vhdx_co_check, > - .bdrv_has_zero_init = bdrv_has_zero_init_1, > + .bdrv_has_zero_init = vhdx_has_zero_init, > > .create_opts = &vhdx_create_opts, > }; I am not familiar with VHDX format to be honest too, but knowing that dynamic format allows for growing and static are preallocated this makes sense. Its a bit amusing and not surprising that the the spec for this format is in .docx. I took a quick look to get a rough impression of the file format. Reviewed-by: Maxim Levitsky Best regards, Maxim Levitsky