Re: [Qemu-devel] [PATCH] qemu-img rebase: allow backing file to be specified as '-'

[Eric Blake <eblake@redhat.com>]

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On 10/15/2012 12:42 PM, Alex Bligh wrote:
> Eric,
> 
> --On 15 October 2012 12:11:02 -0600 Eric Blake <eblake@redhat.com> wrote:
> 
>> On the other hand, if you don't use -u, then qemu-img complains:
>>
>> $ qemu-img rebase  -b ''  bar
>> qemu-img: Could not open new backing file ''
>>
>> So I think a better patch would be to allow rebase-by-pull to work the
>> same as unsafe rebase, by honoring the empty string as a request to pull
>> the entire chain into the destination and leave no backing file.
> 
> Yes, that's exactly the case we're missing. How about the attached (as
> a single patch)
> 
> Also available at:
>  https://github.com/abligh/qemu
> as commits
>  https://github.com/abligh/qemu/commit/4cce9c961fa52a71bd6520a9c499f4dc4b174b97
> 
> and
>  https://github.com/abligh/qemu/commit/4d5b3b431d8dd276f4c564d8a82c6d25cb111381
> 
> 
> -- 
> Alex Bligh

Missing a Signed-off-by; as such, it cannot be taken as is.  Please
repost, and provide an updated subject line and a dedicated commit
message (information such as where to download the commit for testing
belongs after the --- line).  I'm not maintainer for this portion of
code, so I can only review it.

> @@ -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;

As long as you are touching this line, fix the indentation to be
consistent (or is this unusual spacing an artifact of how you pasted
your commit after your '-- ' signature rather than submitting it via
'git send-email' as a proper patch?).  Also, most of qemu uses spaces on
both sides of '='.

But the overall idea looks nice.

-- 
Eric Blake   eblake@redhat.com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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