NFSv4 provides for file delegation wherein a portion of an exported mount can be redirected for service by an alternate system in the cluster. bug 433256 asks for GFS2 support and set lease support and has proposed patches. This BZ is intended for just the GFS2 portion.
Why do we need this bug? So far as I know the original bug was all GFS2 stuff anyway and the only reason that it hadn't been submitted was that it was rejected from 5.2 so that it just needs resubmitting for 5.3 and the other bug can be put back in POST. This one can probably be closed I think.
I was under the impression that there was a bit of kernel work that was fs generic and the the GFS2 (& GPFS) work was separate. If I'm wrong on this count I have no problem with closing this as a dup.