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From:   Anna Schumaker <schumaker.anna@gmail.com>
Date:   Sun, 19 Nov 2023 12:20:36 -0500
Message-ID: <CAFX2JfmUAfDGfYKa5AcNdmp8AsU0tKF=xrj10eormK9RXghkcA@mail.gmail.com>
Subject: Re: NFSv4.1 --> NFSv4.2 client implementation?
To:     Cedric Blancher <cedric.blancher@gmail.com>
Cc:     Linux NFS Mailing List <linux-nfs@vger.kernel.org>
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Hi Ced,

On Sun, Nov 19, 2023 at 11:58=E2=80=AFAM Cedric Blancher
<cedric.blancher@gmail.com> wrote:
>
> On Sat, 18 Nov 2023 at 13:01, Jeff Layton <jlayton@kernel.org> wrote:
> >
> > On Sat, 2023-11-18 at 08:53 +0100, Cedric Blancher wrote:
> > > Good morning!
> > >
> > > What are the differences between NFSv4.1 and NFSv4.2 for a NFSv4
> > > client, if we ignore server-side copy and READ_PLUS support?
> > > Can a NFSv4.1 client then identify itself als NFSv4.2 client?
> > >
> >
> > Yes. I believe that NFSv4.2 consists entirely of optional features over
> > NFSv4.1, so it's legitimate for a client or server to advertise itself
> > as a v4.2 capable, but support none of the features.
>
> Can anyone confirm this? So NFSv4.2 does not require protocol minor
> version negotiation, or how does it work?

I can confirm this. When mounting with NFS v4.2, the client will
detect if the server doesn't support one of the new operations (by the
server returning NFS4ERR_NOTSUPP) and will remember not to try it
again.

Anna

>
> Ced
> --
> Cedric Blancher <cedric.blancher@gmail.com>
> [https://plus.google.com/u/0/+CedricBlancher/]
> Institute Pasteur