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Date:      Mon, 24 Jul 1995 12:00:54 +0100 (BST)
From:      Doug Rabson <dfr@render.com>
To:        "Jordan K. Hubbard" <jkh@freebsd.org>
Cc:        current@freefall.cdrom.com
Subject:   Re: Interesting NFS problem with -current
Message-ID:  <Pine.BSF.3.91.950724115416.12542C-100000@minnow.render.com>
In-Reply-To: <199507240605.XAA00457@throck.cdrom.com>

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On Sun, 23 Jul 1995, Jordan K. Hubbard wrote:

> Scenario:  Several hosts with cross-mount privs managed by AMD.  Host foo
> exports its cdrom drive to host bar, which can see it in /host/foo/cdrom.
> So far, so good.  Now say that foo unmounts the CD in the drive and mounts
> a new one.  Host bar now sees:
> 
> 	<some command>: /host/foo/cdrom: Stale NFS file handle
> 
> In response to any access to the newly mounted CD.  At the
> same time as the access, host foo prints:
> 
> fhtovp: file start miss 60 vs 20
> 
> On its system console.
> 
> I figure this is something to do with NFS v3, but perhaps the data
> is of use to someone working in that area.

The problem is that cd9660 filehandles are only valid for one particular 
disk.  The handle for the old disk was being used for the new one and the 
system was, correctly, complaining.  The extra printf shouldn't really be 
there but it does no harm.  This shouldn't be affected by v3 since the 
filehandle concepts are the same in v2.

When a server changes a disk in its CD drive, all the clients should remount
the filesystem to get a new root filehandle.  With AMD, the only thing you
can do is to reduce the timeout on the client or forcible unmount it using
something like:
	
	amq -u /host/foo/cdrom

--
Doug Rabson, Microsoft RenderMorphics Ltd.	Mail:  dfr@render.com
						Phone: +44 171 251 4411
						FAX:   +44 171 251 0939




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