Re: [PATCH v2 2/1] qemu-img: Add "backing":true to unallocated map segments

[Eric Blake]

On Wed, Jun 23, 2021 at 06:04:19PM +0200, Kevin Wolf wrote:
> > This is fine, but it means that this flag will present in all ranges,
> > instead of only in unallocated ranges (what this patch is doing).
> 
> An argument for always having the flag would be that it's probably
> useful for a tool to know whether a given block is actually absent or
> whether it's just running an old qemu-img.
> 
> If we didn't care about this, I would still define the actual value, but
> also document a default.

So to summarize, it looks like my v3 will have the best chance of
approval if I go with always outputting the new field (instead of only
on one of its two boolean values), and put it at the end of the JSON
output.  It also looks like we have consensus on spelling the new
field "present":true for data found in the backing chain, and
"present":false for places where we would defer to another file if a
backing file is later added.

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