From patchwork Mon Jan 13 20:18:45 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeff Cody X-Patchwork-Id: 310374 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 147AA2C008F for ; Tue, 14 Jan 2014 07:21:01 +1100 (EST) Received: from localhost ([::1]:44855 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1W2o0I-0005TY-Ln for incoming@patchwork.ozlabs.org; Mon, 13 Jan 2014 15:20:58 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:58292) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1W2nyN-0002x2-2T for qemu-devel@nongnu.org; Mon, 13 Jan 2014 15:19:04 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1W2nyG-0003A2-V2 for qemu-devel@nongnu.org; Mon, 13 Jan 2014 15:18:59 -0500 Received: from mx1.redhat.com ([209.132.183.28]:40488) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1W2nyG-00039x-Lr for qemu-devel@nongnu.org; Mon, 13 Jan 2014 15:18:52 -0500 Received: from int-mx11.intmail.prod.int.phx2.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.24]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id s0DKIpaK019558 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Mon, 13 Jan 2014 15:18:51 -0500 Received: from localhost (ovpn-112-26.phx2.redhat.com [10.3.112.26]) by int-mx11.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id s0DKInJp003857 (version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=NO); Mon, 13 Jan 2014 15:18:51 -0500 From: Jeff Cody To: qemu-devel@nongnu.org Date: Mon, 13 Jan 2014 15:18:45 -0500 Message-Id: <677e470b5c2823a06afd63ba72f17f083d944fa3.1389644007.git.jcody@redhat.com> In-Reply-To: References: In-Reply-To: References: X-Scanned-By: MIMEDefang 2.68 on 10.5.11.24 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 209.132.183.28 Cc: kwolf@redhat.com, famz@redhat.com, stefanha@redhat.com Subject: [Qemu-devel] [PATCH 1/2] block: resize backing file image during offline commit, if necessary X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Currently, if an image file is logically larger than its backing file, commiting it via 'qemu-img commit' will fail. For instance, if we have a base image with a virtual size 10G, and a snapshot image of size 20G, then committing the snapshot offline with 'qemu-img commit' will likely fail. This will automatically attempt to resize the base image, if the snapshot image to be committed is larger. Signed-off-by: Jeff Cody --- block.c | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-) diff --git a/block.c b/block.c index 64e7d22..5e895fa 100644 --- a/block.c +++ b/block.c @@ -1876,10 +1876,10 @@ int bdrv_check(BlockDriverState *bs, BdrvCheckResult *res, BdrvCheckMode fix) int bdrv_commit(BlockDriverState *bs) { BlockDriver *drv = bs->drv; - int64_t sector, total_sectors; + int64_t sector, total_sectors, length; int n, ro, open_flags; int ret = 0; - uint8_t *buf; + uint8_t *buf = NULL; char filename[PATH_MAX]; if (!drv) @@ -1904,7 +1904,19 @@ int bdrv_commit(BlockDriverState *bs) } } - total_sectors = bdrv_getlength(bs) >> BDRV_SECTOR_BITS; + length = bdrv_getlength(bs); + + /* If our top snapshot is larger than the backing file image, + * grow the backing file image if possible. If not possible, + * we must return an error */ + if (length > bdrv_getlength(bs->backing_hd)) { + ret = bdrv_truncate(bs->backing_hd, length); + if (ret < 0) { + goto ro_cleanup; + } + } + + total_sectors = length >> BDRV_SECTOR_BITS; buf = g_malloc(COMMIT_BUF_SECTORS * BDRV_SECTOR_SIZE); for (sector = 0; sector < total_sectors; sector += n) {