pNFS/NFSv4: Improve rejection of out-of-order layouts

pNFS/NFSv4: Improve rejection of out-of-order layouts

[ Upstream commit d29b468da4f940bd2bff2628ba8d2d652671d244 ]

If a layoutget ends up being reordered w.r.t. a layoutreturn, e.g. due
to a layoutget-on-open not knowing a priori which file to lock, then we
must assume the layout is no longer being considered valid state by the
server.
Incrementally improve our ability to reject such states by using the
cached old stateid in conjunction with the plh_barrier to try to
identify them.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>