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

[Kevin Wolf <kwolf@redhat.com>]

Am 29.06.2021 um 09:23 hat Vladimir Sementsov-Ogievskiy geschrieben:
> 28.06.2021 20:42, Eric Blake wrote:
> > 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.
> > 
> 
> I didn't follow the discussion carefully, but that sounds good to me.

To me, too.

> What's the decision about patch 1?

I think we won't need patch 1 (and the potential backwards compatibility
problems it would introduce) when we have this one.

Kevin