RE: LOOKUP vs OPEN in NFSV4

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From: Noveck, Dave (Dave.Noveck@netapp.com)
Date: 07/03/01-06:59:47 AM Z


Message-ID: <8C610D86AF6CD4119C9800B0D0499E333354D5@red.nane.netapp.com>
From: "Noveck, Dave" <Dave.Noveck@netapp.com>
Subject: RE: LOOKUP vs OPEN in NFSV4
Date: Tue, 3 Jul 2001 04:59:47 -0700 

Well, if you do a LOOKUP or OPEN, you (the client) has
to be interested in the result, while for some other
operations that change the current filehandle, this 
may not be the case.  So I would not extend this to
any other ops.

As far as the chances of making such a change, they 
aren't very great because most people within the 
working group are satisfied with the GETFH approach.
The size of the change isn't the issue.

 
-----Original Message-----
From: Som [mailto:somenathb@yahoo.com]
Sent: Tuesday, July 03, 2001 12:06 AM
To: Noveck, Dave; nfsv4-wg@sunroof.eng.sun.com
Subject: RE: LOOKUP vs OPEN in NFSV4



--- "Noveck, Dave" <Dave.Noveck@netapp.com> wrote:
> Som wrote:
> > 3. Why don't the structure OPEN4resok contain the
> OPEN
> > generated filehandle instead of client doing one
> more
> > GETFH and getting the same filehandle? It atleast
> > reduces one operation for each open! 
> 
> Actually, I think OPEN and LOOKUP should directly
> return
> the filehandle (and not just when the op succeeds),
> but 
> this is very much a minority opinion in the working
> group.
> 
> V4 only returns handles via GETFH.  Ops that produce
> filehandles only change the current filehandle and
> there
> is a value in having that kind of uniformity.
> 
> The reason I think that LOOKUP and OPEN should
> return
> filehandles has to do with the handling of
> multi-component
> lookups/opens.  If a lookup encounters a symlink (or
> some
> other error situation), you'd like to be able to
> restart 
> the process at the point of failure, which means
> that you 
> need the filehandle where you stopped.  A
> COMPOUNDEDed
> GETFH can't do it, since the error stops the
> request,
> preventing the GETFH from being executed.  This
> makes 
> multi-component lookup/open kind of useless in any 
> environment where symlink might be encountered.
> 
>  

So, now that we have a very good reason to return
filehandle as part of OPEN4resok structure , applying
the same consistency rule ( :-) ) , why not return
filehandles for every state modifying operations? I
mean whenever client has to do GETFH, why not just
return the result always in OPEN4resok strucutre? 

Since NFSV4 is a very new protocol from earlier
versions this change should be possible to do....this
also saves considerable amount of wire traffic...is
this too big a change for NFSV4?

thanks, som.

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