From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([209.51.188.92]:60989) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hL4Lz-0007bi-FX for qemu-devel@nongnu.org; Mon, 29 Apr 2019 07:21:48 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hL4Ly-0008HU-Ii for qemu-devel@nongnu.org; Mon, 29 Apr 2019 07:21:47 -0400 Date: Mon, 29 Apr 2019 13:21:40 +0200 From: Kevin Wolf Message-ID: <20190429112140.GF8492@localhost.localdomain> References: <20190429105741.31033-1-kwolf@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190429105741.31033-1-kwolf@redhat.com> Subject: Re: [Qemu-devel] [PATCH] qcow2: Fix qcow2_make_empty() with external data file List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-block@nongnu.org Cc: mreitz@redhat.com, qemu-stable@nongnu.org, qemu-devel@nongnu.org Am 29.04.2019 um 12:57 hat Kevin Wolf geschrieben: > make_completely_empty() is an optimisated path for bdrv_make_empty() > where completely new metadata is created inside the image file instead > of going through all clusters and discarding them. For an external data > file, however, we actually need to do discard operations on the data > file; just overwriting the qcow2 file doesn't get rid of the data. > > The necessary slow path with an explicit discard operation already > exists for other cases. Use it for external data files, too. > > Cc: qemu-stable@nongnu.org > Signed-off-by: Kevin Wolf > --- > block/qcow2.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/block/qcow2.c b/block/qcow2.c > index 7fbef97aab..097fde56f9 100644 > --- a/block/qcow2.c > +++ b/block/qcow2.c > @@ -4384,7 +4384,8 @@ static int qcow2_make_empty(BlockDriverState *bs) > > if (s->qcow_version >= 3 && !s->snapshots && !s->nb_bitmaps && > 3 + l1_clusters <= s->refcount_block_size && > - s->crypt_method_header != QCOW_CRYPT_LUKS) { > + s->crypt_method_header != QCOW_CRYPT_LUKS && > + !has_data_file(bs)) { > /* The following function only works for qcow2 v3 images (it > * requires the dirty flag) and only as long as there are no > * features that reserve extra clusters (such as snapshots, Oops, I hadn't everything committed yet. I'll add a comment change as well: * LUKS header, or persistent bitmaps), because it completely * empties the image. Furthermore, the L1 table and three * additional clusters (image header, refcount table, one - * refcount block) have to fit inside one refcount block. */ + * refcount block) have to fit inside one refcount block. It + * only resets the image file, i.e. does not work with an + * external data file. */ return make_completely_empty(bs); } Kevin 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=-8.4 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_MUTT 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 77145C43219 for ; Mon, 29 Apr 2019 11:22:47 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 0A60B2084B for ; Mon, 29 Apr 2019 11:22:46 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0A60B2084B 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 ([127.0.0.1]:55949 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hL4Mw-00087J-2U for qemu-devel@archiver.kernel.org; Mon, 29 Apr 2019 07:22:46 -0400 Received: from eggs.gnu.org ([209.51.188.92]:60989) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hL4Lz-0007bi-FX for qemu-devel@nongnu.org; Mon, 29 Apr 2019 07:21:48 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hL4Ly-0008HU-Ii for qemu-devel@nongnu.org; Mon, 29 Apr 2019 07:21:47 -0400 Received: from mx1.redhat.com ([209.132.183.28]:53304) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hL4Lw-0008FX-C8; Mon, 29 Apr 2019 07:21:44 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 779C4821D9; Mon, 29 Apr 2019 11:21:43 +0000 (UTC) Received: from localhost.localdomain (ovpn-116-63.ams2.redhat.com [10.36.116.63]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 6CDC46928F; Mon, 29 Apr 2019 11:21:42 +0000 (UTC) Date: Mon, 29 Apr 2019 13:21:40 +0200 From: Kevin Wolf To: qemu-block@nongnu.org Message-ID: <20190429112140.GF8492@localhost.localdomain> References: <20190429105741.31033-1-kwolf@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline In-Reply-To: <20190429105741.31033-1-kwolf@redhat.com> User-Agent: Mutt/1.11.3 (2019-02-01) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.28]); Mon, 29 Apr 2019 11:21:43 +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] qcow2: Fix qcow2_make_empty() with external data file X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: qemu-devel@nongnu.org, qemu-stable@nongnu.org, mreitz@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Message-ID: <20190429112140.Jh6fbeg3ne9OtkYLChjInYcu1_rxBuQ-52rb8zo6FaM@z> Am 29.04.2019 um 12:57 hat Kevin Wolf geschrieben: > make_completely_empty() is an optimisated path for bdrv_make_empty() > where completely new metadata is created inside the image file instead > of going through all clusters and discarding them. For an external data > file, however, we actually need to do discard operations on the data > file; just overwriting the qcow2 file doesn't get rid of the data. > > The necessary slow path with an explicit discard operation already > exists for other cases. Use it for external data files, too. > > Cc: qemu-stable@nongnu.org > Signed-off-by: Kevin Wolf > --- > block/qcow2.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/block/qcow2.c b/block/qcow2.c > index 7fbef97aab..097fde56f9 100644 > --- a/block/qcow2.c > +++ b/block/qcow2.c > @@ -4384,7 +4384,8 @@ static int qcow2_make_empty(BlockDriverState *bs) > > if (s->qcow_version >= 3 && !s->snapshots && !s->nb_bitmaps && > 3 + l1_clusters <= s->refcount_block_size && > - s->crypt_method_header != QCOW_CRYPT_LUKS) { > + s->crypt_method_header != QCOW_CRYPT_LUKS && > + !has_data_file(bs)) { > /* The following function only works for qcow2 v3 images (it > * requires the dirty flag) and only as long as there are no > * features that reserve extra clusters (such as snapshots, Oops, I hadn't everything committed yet. I'll add a comment change as well: * LUKS header, or persistent bitmaps), because it completely * empties the image. Furthermore, the L1 table and three * additional clusters (image header, refcount table, one - * refcount block) have to fit inside one refcount block. */ + * refcount block) have to fit inside one refcount block. It + * only resets the image file, i.e. does not work with an + * external data file. */ return make_completely_empty(bs); } Kevin