NFSv4: Fix atomicity problems with lock stateid updates

When we update the lock stateid, we really do need to ensure that this is
done under the state->state_lock, and that we are indeed only updating
confirmed locks with a newer version of the same stateid.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

diff --cc fs/nfs/nfs4proc.c
Simple merge