[PATCH] kNFSd: Allow larger writes to sunrpc/svc caches.

[PATCH] kNFSd: Allow larger writes to sunrpc/svc caches.

From: NeilBrown <neilb@cse.unsw.edu.au>

We currently serialize all writes to these caches with queue_io_sem, so we
only needed one buffer.

There is some need for larger-than-one-page writes, so we can just statically
allocate a buffer.