Re: [PATCH v3 1/4] block: Add trivial backing_fmt support to qcow, sheepdog, vmdk

[Eric Blake <eblake@redhat.com>]

On 3/9/20 10:48 AM, Kevin Wolf wrote:

>> Still, the point of this patch is that I want to add -F into all the
>> iotests, and without something along the lines of this patch, all of those
>> iotests are broken for these image formats.  Patch 2 is a lot harder to
>> write if we have to make our use of -F conditional on the image format in
>> question.
> 
> Hm... Maybe _make_test_img can insert/filter out -F depending on $IMGFMT?

I was hoping to avoid that, but yes, if that's what we have to do... :(

The complication is that even if I filter out -F from the command line 
based on $IMGFMT, then I have conditional output (whether backing_fmt= 
or the warning message is output), which means doubling the number of 
expected output cases, or else adding a multi-line filter which is also 
smart enough based on $IMGFMT to translate a warning on one line into an 
addition of a faked backing_fmt= on the next line.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
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