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Re: [Qemu-devel] [PATCH] qemu-img rebase: allow empty file name as new b
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [PATCH] qemu-img rebase: allow empty file name as new backing file to mean rebase with no backing file [attempt 2] |
Date: |
Mon, 15 Oct 2012 14:44:59 -0600 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:16.0) Gecko/20121009 Thunderbird/16.0 |
On 10/15/2012 02:23 PM, Alex Bligh wrote:
Rather long on the subject line; 'git shortlog -30' will give you a
taste for typical commit summary length. Also, you will usually see
[PATCHv2] as the prefix, rather than [PATCH]...[attempt 2] as a suffix,
since 'git am' only strips a [] prefix. It might be better as:
qemu-img rebase: use empty string to rebase without backing file
> 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-imag rebase
s/qemu-imag/qemu-img/
> already supports this when '-u' is used; this adds support when -u is not
> used.
>
> Signed-off-by: Alex Bligh <address@hidden>
> ---
> @@ -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);
Should we error out if the user specifies basefmt but gives the empty
string, instead of silently ignoring the bogus basefmt? But that's
bikeshedding, I can live with what you wrote.
Reviewed-by: Eric Blake <address@hidden>
--
Eric Blake address@hidden +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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