Re: [Qemu-devel] [PATCH v3] qemu-img: Check for backing image if specified during create

[Eric Blake]

On 05/11/2017 10:11 AM, John Snow wrote:
> Or, rather, force the open of a backing image if one was specified
> for creation. Using a similar -unsafe option as rebase, allow qemu-img
> to ignore the backing file validation if possible.
> 
> It may not always be possible, as in the existing case when a filesize
> for the new image was not specified.
> 
> This is accomplished by shifting around the conditionals in
> bdrv_img_create, such that a backing file is always opened unless we
> provide BDRV_O_NO_BACKING. qemu-img is adjusted to pass this new flag
> when -u is provided to create.
> 
> Sorry for the heinous looking diffstat, but it's mostly whitespace.
> 
> Inspired by: https://bugzilla.redhat.com/show_bug.cgi?id=1213786
> 
> Signed-off-by: John Snow <address@hidden>
> ---
> v3: Rebased
> 

> +++ b/qemu-img.c
> @@ -145,9 +145,11 @@ static void QEMU_NORETURN help(void)
>             "  'snapshot_id_or_name' is deprecated, use 'snapshot_param'\n"
>             "    instead\n"
>             "  '-c' indicates that target image must be compressed (qcow 
> format only)\n"
> -           "  '-u' enables unsafe rebasing. It is assumed that old and new 
> backing file\n"
> -           "       match exactly. The image doesn't need a working backing 
> file before\n"
> -           "       rebasing in this case (useful for renaming the backing 
> file)\n"
> +           "  '-u' allows unsafe backing chains. For rebasing, it is assumed 
> that old and new\n"
> +           "       backing file match exactly. The image doesn't need a 
> working backing file\n"
> +           "       before rebasing in this case (useful for renaming the 
> backing file)\n"
> +           "       For image creation, allow creating without attempting to"
> +           "       open the backing file.\n"

You forgot to fix my v2 review comments ('.', \n)

With that (actually) fixed,
Reviewed-by: Eric Blake <address@hidden>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org

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