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Re: [Qemu-devel] [PATCHv4] qemu-img rebase: use empty string to rebase w
From: |
Kevin Wolf |
Subject: |
Re: [Qemu-devel] [PATCHv4] qemu-img rebase: use empty string to rebase without backing file |
Date: |
Wed, 17 Oct 2012 16:45:39 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:13.0) Gecko/20120605 Thunderbird/13.0 |
Am 16.10.2012 14:46, schrieb Alex Bligh:
> 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 <address@hidden>
> ---
> qemu-img.c | 29 +++++++++++++++++++----------
> qemu-img.texi | 4 +++-
> 2 files changed, 22 insertions(+), 11 deletions(-)
>
> Also obtainable from:
> https://github.com/abligh/qemu.git
> Commit at:
>
> https://github.com/abligh/qemu/commit/982ec105018f9901619663642de9d0a5de86799d
>
> diff --git a/qemu-img.c b/qemu-img.c
> index f17f187..2816f37 100644
> --- a/qemu-img.c
> +++ b/qemu-img.c
> @@ -1558,13 +1558,15 @@ 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 +1582,7 @@ 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 +1594,9 @@ 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 +1633,7 @@ 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 +1679,12 @@ 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) {
I think this needs to be out_baseimg, otherwise -u is broken. I've
updated the patch, please check if you agree with the fix.
Kevin