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From: Neil Brown <neilb@cse.unsw.edu.au>
To: Elliot Lee <sopwith@redhat.com>
Date: Wed, 12 Dec 2001 12:21:28 +1100 (EST)
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Cc: "David S. Miller" <davem@redhat.com>, <linux-kernel@vger.kernel.org>
Subject: Re: knfsd and FS_REQUIRES_DEV
In-Reply-To: message from Elliot Lee on Tuesday December 11
In-Reply-To: <20011211.162011.21927662.davem@redhat.com>
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On Tuesday December 11, sopwith@redhat.com wrote:
> I'm not worried about problems where files mysteriously disappear due to
> me screwing up inode numbers in my code, only about causing kernel panics
> or other Bad Things in the server's kernel. If I were to remove the
> FS_REQUIRES_DEV check (or, more likely, submit a patch adding an nfsd
> module option to remove the check...), what are the worst things that
> could theoretically and realistically happen?

If you just removed the check, the worst that would happen is that
after a server reboot you have to remount everything on your clients.

If you submit a patch to make it an option, the worst that can happen
is that I jump on you (but I'm not a good long jumper, so you are
pretty safe).

I plan to make a change to knfsd in the near future so that you can
have an option like:
   fs=27
in /etc/exports and the the kernel puts the magic number "27" in the
filehandle instead of the device number.  Then as long as you export
each filesystem with a unique and consistant fs number, you won't need
to worry about the instability of device numbers.

NeilBrown
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