nfsd41: Deny new lock before RECLAIM_COMPLETE done

Before nfs41 client's RECLAIM_COMPLETE done, nfs server should deny any
new locks or opens.

rfc5661:

   " Whenever a client establishes a new client ID and before it does
   the first non-reclaim operation that obtains a lock, it MUST send a
   RECLAIM_COMPLETE with rca_one_fs set to FALSE, even if there are no
   locks to reclaim.  If non-reclaim locking operations are done before
   the RECLAIM_COMPLETE, an NFS4ERR_GRACE error will be returned. "
Signed-off-by: Mi Jinlong <mijinlong@cn.fujitsu.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

fs/nfsd/nfs4proc.c

@@ -291,6 +291,15 @@ nfsd4_open(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 	if (open->op_create && open->op_claim_type != NFS4_OPEN_CLAIM_NULL)
 		return nfserr_inval;
 
+	/*
+	 * RFC5661 18.51.3
+	 * Before RECLAIM_COMPLETE done, server should deny new lock
+	 */
+	if (nfsd4_has_session(cstate) &&
+	    !cstate->session->se_client->cl_firststate &&
+	    open->op_claim_type != NFS4_OPEN_CLAIM_PREVIOUS)
+		return nfserr_grace;
+
 	if (nfsd4_has_session(cstate))
 		copy_clientid(&open->op_clientid, cstate->session);