From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:34608) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1W5n5B-0006uW-CA for qemu-devel@nongnu.org; Tue, 21 Jan 2014 20:58:27 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1W5n55-0008TE-Bo for qemu-devel@nongnu.org; Tue, 21 Jan 2014 20:58:21 -0500 Received: from mx1.redhat.com ([209.132.183.28]:14112) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1W5n55-0008TA-2i for qemu-devel@nongnu.org; Tue, 21 Jan 2014 20:58:15 -0500 Received: from int-mx12.intmail.prod.int.phx2.redhat.com (int-mx12.intmail.prod.int.phx2.redhat.com [10.5.11.25]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id s0M1wEXW014638 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Tue, 21 Jan 2014 20:58:14 -0500 Date: Wed, 22 Jan 2014 09:58:15 +0800 From: Fam Zheng Message-ID: <20140122015815.GE24604@T430.redhat.com> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Subject: Re: [Qemu-devel] [PATCH v2 1/3] block: resize backing file image during offline commit, if necessary List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jeff Cody Cc: kwolf@redhat.com, qemu-devel@nongnu.org, stefanha@redhat.com On Tue, 01/21 11:31, Jeff Cody wrote: > 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 | 23 ++++++++++++++++++++--- > 1 file changed, 20 insertions(+), 3 deletions(-) > > diff --git a/block.c b/block.c > index 64e7d22..dea7591 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, backing_length; > int n, ro, open_flags; > int ret = 0; > - uint8_t *buf; > + uint8_t *buf = NULL; > char filename[PATH_MAX]; > > if (!drv) > @@ -1904,7 +1904,24 @@ int bdrv_commit(BlockDriverState *bs) > } > } > > - total_sectors = bdrv_getlength(bs) >> BDRV_SECTOR_BITS; > + length = bdrv_getlength(bs); > + backing_length = bdrv_getlength(bs->backing_hd); > + > + if (length < 0 || backing_length < 0) { > + goto ro_cleanup; > + } > + > + /* 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 > backing_length) { > + 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) { > -- > 1.8.3.1 > Reviewed-by: Fam Zheng