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From: Neil Brown <neilb@cse.unsw.edu.au>
To: Stephan von Krawczynski <skraw@ithnet.com>
Date: Wed, 6 Aug 2003 11:12:38 +1000
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Subject: Re: FS: hardlinks on directories
In-Reply-To: message from Stephan von Krawczynski on Tuesday August 5
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On Tuesday August 5, skraw@ithnet.com wrote:
> > > Hm, and I just found out that re-exporting "mount --bind" volumes does not
> > > work over nfs...
> > > 
> > > Is this correct, Neil?
> > 
> > Yes, though there is a reasonable chance that it can be made to work
> > with linux-2.6.0 and nfs-utils-1.1.0 (neither of which have been
> > released yet:-)
> 
> Is this a complex issue? Can you imagine a not-too-big sized patch can make it
> work in 2.4? What is the basic reason it does in fact not work?

On reflection, it could probably work in 2.4 and current nfs-utils,
but admin might be a bit clumsy.

To allow knfsd to see a mountpoint, you have to export the mounted
directory with the "nohide" option.  Currently "nohide" only works
properly for exports to specific hosts, not to wildcarded hosts or
netgroups.
So if your /etc/export contains:

  /path/to/some/--bind/mountpoint servername(nohide,....)

for every mountpoint and every server, then it should work.

In 2.6, you can (will be able to) just export the top level mount
point with "crossmnt" and it should all work for you.

Getting that functionality into 2.4 would be a very big job.

NeilBrown