Re: [nfsv4] CREATE_SESSION backchannel question

"J. Bruce Fields" <bfields@fieldses.org> Thu, 14 October 2010 19:32 UTC

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Date: Thu, 14 Oct 2010 15:33:47 -0400
From: "J. Bruce Fields" <bfields@fieldses.org>
To: "Matt W. Benjamin" <matt@linuxbox.com>
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Cc: nfsv4 <nfsv4@ietf.org>
Subject: Re: [nfsv4] CREATE_SESSION backchannel question
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On Thu, Oct 14, 2010 at 12:26:01PM -0400, bfields wrote:
> On Thu, Oct 14, 2010 at 11:07:33AM -0400, Matt W. Benjamin wrote:
> > I wondered a bit about the server's backchannel preferences in
> > CREATE_SESSION, for example, if the server implementation would prefer
> > (or even require) a dedicated backchannel.  The server can accept or
> > reject a client request to use the current connection as a forechannel
> > and backchannel.
> 
> I'd never actually noticed that was allowed!
> 
> > If the server clears the backchannel flag, or the
> > client did not set it, can the server expect that the client will
> > offer a backchannel in a subsequent BIND_CONN_TO_SESSION (under its
> > obligations under 2.9.2, item 3).
> 
> I don't think the existing Linux client is prepared to handle that; more
> likely telling it that the backchannel wasn't set up will cause it to
> destroy the client and try to create a new one, resulting in an infinite

(Sorry, I meant "destroy the session and try to create a new one".)

--b.

> loop....  (But I haven't tested that, much less other clients.)
> 
> It seems like mildly antisocial behavior on the part of the server, but
> I can believe it would be convenient to not have to handle the
> shared-connection case, and probably wouldn't be difficult to handle on
> the client.
> 
> --b.