NFS 'noac' attr

[Alan Cox]

> Should the 'noac' attribute guarantee that directory contents are
> collected from the master and written back to the master rather
> than being cached locally? And is this done at diropen/dirclose?

It'll guarantee some stuff isn't cached but not namespace. So the date
will be right but perhaps not other things.

NFS locking is an interesting art as you've really only got lockf() and
open/close consistency guarantees. 

Alan