Subject: [nfsv4] Mirja Kühlewind's No Objection on draft-ietf-nfsv4-rpcrdma-cm-pvt-data-07: (with COMMENT)

From: Mirja Kühlewind via Datatracker <[email-masked]>
Date: Wed, 19 Feb 2020 06:24:49 -0800

Mirja Kühlewind has entered the following ballot position for
draft-ietf-nfsv4-rpcrdma-cm-pvt-data-07: No Objection

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COMMENT:
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One quick thought/comment: Another option for extensibility would be to use one
of the reserved flags to e.g. extend the fields of the private data field.
However, the draft states at all reserved flags need to be zero with version 1.
This seems to be a bit of a waste of space but moreover it's a lost opportunity
for an easy way to extend the private data field. Why was that decided?

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From: Chuck Lever <[email-masked]>
Date: Wed, 19 Feb 2020 15:46:13 -0500

Hello Mirja-

> On Feb 19, 2020, at 9:24 AM, Mirja Kühlewind via Datatracker <[email-masked]> wrote:
> 

The common way to extend this kind of data structures, I assumed,
was to use the version field. The set of defined flag fields cannot
change without a bump in the version number.

I would be interested to consider another way to handle extension,
though at this point there is already an implementation of this
protocol, which limits our ability to adjust the structure format
too much.

Thanks for your comment!

--
Chuck Lever

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From: Mirja Kuehlewind <[email-masked]>
Date: Thu, 20 Feb 2020 09:42:59 +0100

Hi Chuck,

See below.

> On 19. Feb 2020, at 21:46, Chuck Lever <[email-masked]> wrote:
> 
> Hello Mirja-
> 

Yes that is a good and common way. However, usually if you have reserved flags, there is also a way to make use of those flags without changing the version which seem not the case here.

> protocol, which limits our ability to adjust the structure format

I would not think that this would change anything in the current implementation, as the current implementation should just ignore the flags. However, this is no big deal, but maybe it’s something to think about if there is a way to make better use of these reserved flags/bits. 

Mirja

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From: Chuck Lever <[email-masked]>
Date: Thu, 20 Feb 2020 09:09:30 -0500

> On Feb 20, 2020, at 3:42 AM, Mirja Kuehlewind <[email-masked]> wrote:
> 
> Hi Chuck,
> 
> See below.
> 

Right, I can think of no reason for this in the cm-pvt-data case other
than simple tradition. And by the way, the text in cm-pvt-data has been
updated due to recent ballot comments. The Flags field has been split
into a Reserved field and a 1-bit flag. The descriptions now read:

Reserved:
This 7-bit field is unused. Senders MUST set these bits to zero and
receivers MUST ignore their value.

R:
This 1-bit field indicates that the sender supports remote invalidation.
The field is set and interpreted as described in Section 4.1.

> I would not think that this would change anything in the current implementation, as the current implementation should just ignore the flags. However, this is no big deal, but maybe it’s something t…

I am intrigued to learn more. Do you know of an example RFC or
Internet-Draft?

--
Chuck Lever

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From: Mirja Kuehlewind <[email-masked]>
Date: Thu, 20 Feb 2020 15:28:25 +0100

> On 20. Feb 2020, at 15:09, Chuck Lever <[email-masked]> wrote:
> 
> 
> 

Great! Thanks!

> I am intrigued to learn more. Do you know of an example RFC or

Maybe https://tools.ietf.org/html/rfc6709

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From: Chuck Lever <[email-masked]>
Date: Thu, 20 Feb 2020 12:28:45 -0500

> On Feb 20, 2020, at 9:28 AM, Mirja Kuehlewind <[email-masked]> wrote:
> 

Thank you! I had forgotten about this valuable document.

--
Chuck Lever