Re: [PATCH v2 3/6] spec: Add NBD_OPT_EXTENDED_HEADERS

[Wouter Verhelst]

On Fri, Mar 03, 2023 at 04:36:41PM -0600, Eric Blake wrote:
> On Wed, Feb 22, 2023 at 11:49:18AM +0200, Wouter Verhelst wrote:
> > On Mon, Nov 14, 2022 at 04:46:52PM -0600, Eric Blake wrote:
[...]
> > > +  Note that even when extended headers are in use, the client MUST be
> > > +  prepared for the server to use either the compact or extended chunk
> > > +  type, regardless of whether the client's hinted effect length was
> > > +  more or less than 32 bits; but the server MUST use exactly one of
> > > +  the two chunk types per negotiated metacontext ID.
> > 
> > Is this last paragraph really a good idea? I would think it makes more
> > sense to require the new format if we're already required to support it
> > on both sides anyway.
> 
> My proof of implementation was easier to code when I didn't have to
> resize the block status reply sizing in the same patch as adding the
> 64-bit headers.  But if you think requiring the 64-bit reply type
> always (and forbidding the 32-bit reply) when extended headers are in
> force, that's also possible.

Intuitively, this sounds off. It would seem to me that it's easier to do
if you don't have to have a conditional on each received data packet.
But maybe I'm missing something -- I haven't done an implementation yet,
anyway.

-- 
     w@uter.{be,co.za}
wouter@{grep.be,fosdem.org,debian.org}

I will have a Tin-Actinium-Potassium mixture, thanks.