From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45279) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1W6S97-0001Io-RU for qemu-devel@nongnu.org; Thu, 23 Jan 2014 16:49:15 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1W6S91-0001iz-SA for qemu-devel@nongnu.org; Thu, 23 Jan 2014 16:49:09 -0500 Received: from mx1.redhat.com ([209.132.183.28]:38025) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1W6S91-0001iv-Ic for qemu-devel@nongnu.org; Thu, 23 Jan 2014 16:49:03 -0500 Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id s0NLn27i003428 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Thu, 23 Jan 2014 16:49:03 -0500 From: Jeff Cody Date: Thu, 23 Jan 2014 16:48:55 -0500 Message-Id: In-Reply-To: References: In-Reply-To: References: Subject: [Qemu-devel] [PATCH v3 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: qemu-devel@nongnu.org Cc: kwolf@redhat.com, famz@redhat.com, stefanha@redhat.com 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 Reviewed-by: Fam Zheng Reviewed-by: Eric Blake --- 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