nfsd: Fix SP4_MACH_CRED negotiation in EXCHANGE_ID

 - don't BUG_ON() when not SP4_NONE
 - calculate recv and send reserve sizes correctly
Signed-off-by: Weston Andros Adamson <dros@netapp.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

fs/nfsd/nfs4proc.c

@@ -1524,7 +1524,7 @@ static inline u32 nfsd4_write_rsize(struct svc_rqst *rqstp, struct nfsd4_op *op)
 static inline u32 nfsd4_exchange_id_rsize(struct svc_rqst *rqstp, struct nfsd4_op *op)
 {
 	return (op_encode_hdr_size + 2 + 1 + /* eir_clientid, eir_sequenceid */\
-		1 + 1 + 0 + /* eir_flags, spr_how, SP4_NONE (for now) */\
+		1 + 1 + 2 + /* eir_flags, spr_how, spo_must_enforce & _allow */\
 		2 + /*eir_server_owner.so_minor_id */\
 		/* eir_server_owner.so_major_id<> */\
 		XDR_QUADLEN(NFS4_OPAQUE_LIMIT) + 1 +\

fs/nfsd/nfs4xdr.c

@@ -3360,7 +3360,8 @@ nfsd4_encode_exchange_id(struct nfsd4_compoundres *resp, __be32 nfserr,
 		8 /* eir_clientid */ +
 		4 /* eir_sequenceid */ +
 		4 /* eir_flags */ +
-		4 /* spr_how (SP4_NONE) */ +
+		4 /* spr_how */ +
+		8 /* spo_must_enforce, spo_must_allow */ +
 		8 /* so_minor_id */ +
 		4 /* so_major_id.len */ +
 		(XDR_QUADLEN(major_id_sz) * 4) +
@@ -3372,8 +3373,6 @@ nfsd4_encode_exchange_id(struct nfsd4_compoundres *resp, __be32 nfserr,
 	WRITE32(exid->seqid);
 	WRITE32(exid->flags);
 
-	/* state_protect4_r. Currently only support SP4_NONE */
-	BUG_ON(exid->spa_how != SP4_NONE);
 	WRITE32(exid->spa_how);
 	switch (exid->spa_how) {
 	case SP4_NONE: