nfsd41: stateid handling

When sessions are used, stateful operation sequenceid and stateid handling
are not used. When sessions are used,  on the first open set the seqid to 1,
mark state confirmed and skip seqid processing.

When sessionas are used the stateid generation number is ignored when it is zero
whereas without sessions bad_stateid or stale stateid is returned.

Add flags to propagate session use to all stateful ops and down to
check_stateid_generation.

Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: Andy Adamson <andros@netapp.com>
[nfsd4_has_session should return a boolean, not u32]
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
[nfsd41: pass nfsd4_compoundres * to nfsd4_process_open1]
[nfsd41: calculate HAS_SESSION in nfs4_preprocess_stateid_op]
[nfsd41: calculate HAS_SESSION in nfs4_preprocess_seqid_op]
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>