From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:42107) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TNodD-0001uG-9r for qemu-devel@nongnu.org; Mon, 15 Oct 2012 13:39:15 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TNodA-0006L6-M4 for qemu-devel@nongnu.org; Mon, 15 Oct 2012 13:39:11 -0400 Received: from mail.avalus.com ([89.16.176.221]:58485) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TNodA-0006Kb-Cb for qemu-devel@nongnu.org; Mon, 15 Oct 2012 13:39:08 -0400 Date: Mon, 15 Oct 2012 18:29:34 +0100 From: Alex Bligh Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline Subject: [Qemu-devel] [PATCH] qemu-img rebase: allow backing file to be specified as '-' Reply-To: Alex Bligh List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Alex Bligh This patch allows qemu-img rebase to rebase an image to have no backing file, as opposed to merely allowing it to rebase to an existing backing file. Patch below, or pull from git at: https://github.com/abligh/qemu.git Commit visible at: https://github.com/abligh/qemu/commit/4d5b3b431d8dd276f4c564d8a82c6d25cb111381 Signed-off-by: Alex Bligh --- qemu-img.c | 26 ++++++++++++++++---------- qemu-img.texi | 4 +++- 2 files changed, 19 insertions(+), 11 deletions(-) diff --git a/qemu-img.c b/qemu-img.c index f17f187..770e221 100644 --- a/qemu-img.c +++ b/qemu-img.c @@ -1558,13 +1558,14 @@ static int img_rebase(int argc, char **argv) error_report("Could not open old backing file '%s'", backing_name); goto out; } - - bs_new_backing = bdrv_new("new_backing"); - ret = bdrv_open(bs_new_backing, out_baseimg, BDRV_O_FLAGS, + if (strcmp("-", out_baseimg)) { + bs_new_backing = bdrv_new("new_backing"); + ret = bdrv_open(bs_new_backing, out_baseimg, BDRV_O_FLAGS, new_backing_drv); - if (ret) { - error_report("Could not open new backing file '%s'", out_baseimg); - goto out; + if (ret) { + error_report("Could not open new backing file '%s'", out_baseimg); + goto out; + } } } @@ -1580,7 +1581,7 @@ static int img_rebase(int argc, char **argv) if (!unsafe) { uint64_t num_sectors; uint64_t old_backing_num_sectors; - uint64_t new_backing_num_sectors; + uint64_t new_backing_num_sectors=0; uint64_t sector; int n; uint8_t * buf_old; @@ -1592,7 +1593,8 @@ static int img_rebase(int argc, char **argv) bdrv_get_geometry(bs, &num_sectors); bdrv_get_geometry(bs_old_backing, &old_backing_num_sectors); - bdrv_get_geometry(bs_new_backing, &new_backing_num_sectors); + if (bs_new_backing) + bdrv_get_geometry(bs_new_backing, &new_backing_num_sectors); local_progress = (float)100 / (num_sectors / MIN(num_sectors, IO_BUF_SIZE / 512)); @@ -1629,7 +1631,7 @@ static int img_rebase(int argc, char **argv) } } - if (sector >= new_backing_num_sectors) { + if (sector >= new_backing_num_sectors || !bs_new_backing) { memset(buf_new, 0, n * BDRV_SECTOR_SIZE); } else { if (sector + n > new_backing_num_sectors) { @@ -1675,7 +1677,11 @@ static int img_rebase(int argc, char **argv) * backing file are overwritten in the COW file now, so the visible content * doesn't change when we switch the backing file. */ - ret = bdrv_change_backing_file(bs, out_baseimg, out_basefmt); + if (bs_new_backing) + ret = bdrv_change_backing_file(bs, out_baseimg, out_basefmt); + else + ret = bdrv_change_backing_file(bs, NULL, NULL); + if (ret == -ENOSPC) { error_report("Could not change the backing file to '%s': No " "space left in the file header", out_baseimg); diff --git a/qemu-img.texi b/qemu-img.texi index 8b05f2c..7c29f23 100644 --- a/qemu-img.texi +++ b/qemu-img.texi @@ -148,7 +148,9 @@ Changes the backing file of an image. Only the formats @code{qcow2} and The backing file is changed to @var{backing_file} and (if the image format of @var{filename} supports this) the backing file format is changed to -@var{backing_fmt}. +@var{backing_fmt}. If @var{backing_file} is specified as ``-'', then the image +is rebased onto no backing file (i.e. it will exist independently of any +backing file). There are two different modes in which @code{rebase} can operate: @table @option -- 1.7.0.4