Re: knfsd and FS_REQUIRES_DEV

[torvalds@transmeta.com (Linus Torvalds)]

In article <20011211.162011.21927662.davem@redhat.com>,
David S. Miller <davem@redhat.com> wrote:
>   From: Elliot Lee <sopwith@redhat.com>
>   Date: Tue, 11 Dec 2001 19:13:48 -0500 (EST)
>
>   I'm looking for information on knfsd's requirement that a filesystem be
>   FS_REQUIRES_DEV in order to export it. Would someone point me in the right
>   direction?
>   
>   Needing to implement some not-quite-kosher exports,
>
>NFSD puts dev/ino into the filehandles it gives to the
>client, it uses this to lookup the inode in question.

Well, that actually could work with things like /proc, which actually
has meaningful inode numbers. They may not be stable across reboots, of
course, nor even really stable in general, but in _theory_ there's
nothing to keep us from exporting /proc files and potentially other
virtual filesystems.

In practice I suspect there are tons of other problems, not the least of
which is that /proc doesn't give a proper filesize. 

Other not-so-kosher filesystems (ie tmpfs) might be easier than /proc in
those respects. 

		Linus