Use nfs4_sanity_check_FH for nfsa4_op_delegreturn

For correctness to RFC, replace NFS4ERR_ISDIR with NFS4ERR_INVAL.

Signed-off-by: Frank S. Filz <ffilzlnx@mindspring.com>
Reorganize state_t and remove some typedefs

Signed-off-by: Frank S. Filz <ffilzlnx@mindspring.com>
Hold state_lock in write for nfs4_return_one_state and state_lookup_layout_state

nfs4_return_one_state does a glist_length which requires the state lock,
since most callers hold the lock, change so all callers hold the lock.

Signed-off-by: Frank S. Filz <ffilzlnx@mindspring.com>
Add refcount to state_t

Signed-off-by: Frank S. Filz <ffilzlnx@mindspring.com>
Eliminate separate deleg_data structue

Signed-off-by: Frank S. Filz <ffilzlnx@mindspring.com>