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From: Trond Myklebust <trond.myklebust@fys.uio.no>
Organization: Dept. of Physics, University of Oslo
To: NIIBE Yutaka <gniibe@m17n.org>
Subject: Re: BUG REPORT: kernel nfs between 2.4.19-pre2 (server) and 2.2.21-pre3 (client)
Date: Tue, 19 Mar 2002 15:45:38 +0100
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Cc: Stephan von Krawczynski <skraw@ithnet.com>,
        linux-kernel <linux-kernel@vger.kernel.org>
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On Tuesday 19. March 2002 00:57, NIIBE Yutaka wrote:
> File handle must be unique.  But I think that it may be reused (for
> different type).  Client side cache should handle this case, IMO.

No...

>From RFC1094:
----------------
2.3.3.  fhandle

          typedef opaque fhandle[FHSIZE];

      The "fhandle" is the file handle passed between the server and the
      client.  All file operations are done using file handles to refer
      to a file or directory.  The file handle can contain whatever
      information the server needs to distinguish an individual file.
-----------------
IOW: the server is required to distinguish an individual file.

Note that there is no time limit on this: if I try to write to a file that 
was deleted behind my back, the server is supposed to be able to determine 
which file I was writing to.

This is further clarified in RFC1813:
-----------------
      If two file handles from the same server are equal, they must refer to
      the same file
------------------

Again: at no point does the RFC say that there is a timelimit on the above 
(unlike the so-called 'volatile filehandles' that were introduced for NFSv4)

Indeed if you think about it, then there is no way the RFC *can* allow the 
client to take the burden: we are talking about a stateless system. Unless 
the server has a way of notifying the client that a filehandle is invalid, 
and/or the file was deleted there is no way that the client can know...

Cheers,
  Trond
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