From patchwork Mon Oct 15 20:50:41 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alex Bligh X-Patchwork-Id: 191663 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 307932C009F for ; Tue, 16 Oct 2012 07:50:58 +1100 (EST) Received: from localhost ([::1]:41999 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TNrcm-0007M1-Ap for incoming@patchwork.ozlabs.org; Mon, 15 Oct 2012 16:50:56 -0400 Received: from eggs.gnu.org ([208.118.235.92]:51521) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TNrcc-0007Li-Es for qemu-devel@nongnu.org; Mon, 15 Oct 2012 16:50:47 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TNrcb-0008Mk-0h for qemu-devel@nongnu.org; Mon, 15 Oct 2012 16:50:46 -0400 Received: from mail.avalus.com ([89.16.176.221]:57817) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TNrca-0008M5-Nz for qemu-devel@nongnu.org; Mon, 15 Oct 2012 16:50:44 -0400 Received: by mail.avalus.com (Postfix) with ESMTPSA id 7F4E2C5617F; Mon, 15 Oct 2012 21:50:43 +0100 (BST) From: Alex Bligh To: qemu-devel@nongnu.org Date: Mon, 15 Oct 2012 21:50:41 +0100 Message-Id: <1350334241-1718-1-git-send-email-alex@alex.org.uk> X-Mailer: git-send-email 1.7.4.1 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.6 (newer, 3) X-Received-From: 89.16.176.221 Cc: alex@alex.org.uk Subject: [Qemu-devel] [PATCHv3] qemu-img rebase: use empty string to rebase without backing file 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 This patch allows an empty filename to be passed as the new base image name for qemu-img rebase to mean base the image on no backing file (i.e. independent of any backing file). According to Eric Blake, qemu-img rebase already supports this when '-u' is used; this adds support when -u is not used. Signed-off-by: Alex Bligh Reviewed-by: Eric Blake --- qemu-img.c | 26 ++++++++++++++++---------- qemu-img.texi | 4 +++- 2 files changed, 19 insertions(+), 11 deletions(-) Also obtainable from: https://github.com/abligh/qemu.git Commit at: https://github.com/abligh/qemu/commit/49cd454aa09062b151710cc7afd4bb7fcf1070d0 diff --git a/qemu-img.c b/qemu-img.c index f17f187..e817498 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 (out_baseimg[0]) { + 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..42ec392 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 ``'' (the empty +string), 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