Re: + knfsd-exportfs-add-exportfsh-header-fix.patch added to -mm tree

[Christoph Hellwig <hch@infradead.org>]

On Wed, May 16, 2007 at 09:55:41AM -0500, Steven French wrote:
> Any ideas what are the minimum export operation(s) that cifs would need to 
> add to export under nfsd?  It was not clear to me after reading the 
> Exporting document in Documentation directory.
> 
> (some users had wanted to export files from Windows servers to nfs clients 
> files by putting an nfs server mounted over cifs in between - I realize 
> that this can corrupt data due to nfs client caching etc., as even in some 
> cases could happen if you try to export a cluster file system under nfsd).

In current mainline knfsd will let you export a filesystem with no method
present at all, but you really need a ->get_parent to not corrupt data
once the dcache gets flushed or you reboot.  After this patchset you
will also need a ->get_dentry instead of the iget fallback before which
was the wrong thing for almost every filesystem.  Unless you actually
have traditional unix filesystem stable 32bit inode numbers and a generation
number you will also need a ->decode_fh and ->encode_fh method, but the
names and semantics of all these will change with some more patches I
have pending.  These patches will also document the requirements a little
better and enforce stricter checks of the required methods.