[RFC] Reinstate NFS exportability for JFFS2.

[David Woodhouse]

On Fri, 2008-05-02 at 11:38 +1000, Neil Brown wrote:
> Why is there a deadlock here?
> Both readdir and lookup are called with i_mutex held on the directory
> so there should need to do any extra locking (he said, naively).  In
> the readdirplus cases, i_mutex is held across both the readdir and the
> lookup....
> 
> One problem with your proposed solution is that filehandles aren't all
> the same length, so you cannot reliably leave space for them.
> 
> Awkward.

Yeah. I think the sanest plan for the short term is, as hch suggests,
just to transplant the existing XFS hack into the nfsd code. That way,
at least we can avoid using the hack for local users. And it makes NFS
export from other file systems (jffs2, btrfs, etc.) easier without
having to put the same hacks in each one.

Git tree at git.infradead.org/users/dwmw2/nfsexport-2.6.git; patch
sequence follows...

-- 
David Woodhouse                            Open Source Technology Centre
David.Woodhouse at intel.com                              Intel Corporation