nfs4.1: Minimal SP4_MACH_CRED implementation

This is a minimal client side implementation of SP4_MACH_CRED.  It will
attempt to negotiate SP4_MACH_CRED iff the EXCHANGE_ID is using
krb5i or krb5p auth.  SP4_MACH_CRED will be used if the server supports the
minimal operations:

 BIND_CONN_TO_SESSION
 EXCHANGE_ID
 CREATE_SESSION
 DESTROY_SESSION
 DESTROY_CLIENTID

This patch only includes the EXCHANGE_ID negotiation code because
the client will already use the machine cred for these operations.

If the server doesn't support SP4_MACH_CRED or doesn't support the minimal
operations, the exchange id will be resent with SP4_NONE.

Signed-off-by: Weston Andros Adamson <dros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
index 7c3956d..01fd84b 100644
--- a/include/linux/nfs_xdr.h
+++ b/include/linux/nfs_xdr.h
@@ -1107,6 +1107,23 @@
 	struct pnfs_commit_bucket *buckets;
 };
 
+#define NFS4_OP_MAP_NUM_LONGS \
+	DIV_ROUND_UP(LAST_NFS4_OP, 8 * sizeof(unsigned long))
+#define NFS4_OP_MAP_NUM_WORDS \
+	(NFS4_OP_MAP_NUM_LONGS * sizeof(unsigned long) / sizeof(u32))
+struct nfs4_op_map {
+	union {
+		unsigned long longs[NFS4_OP_MAP_NUM_LONGS];
+		u32 words[NFS4_OP_MAP_NUM_WORDS];
+	} u;
+};
+
+struct nfs41_state_protection {
+	u32 how;
+	struct nfs4_op_map enforce;
+	struct nfs4_op_map allow;
+};
+
 #define NFS4_EXCHANGE_ID_LEN	(48)
 struct nfs41_exchange_id_args {
 	struct nfs_client		*client;
@@ -1114,6 +1131,7 @@
 	unsigned int 			id_len;
 	char 				id[NFS4_EXCHANGE_ID_LEN];
 	u32				flags;
+	struct nfs41_state_protection	state_protect;
 };
 
 struct nfs41_server_owner {
@@ -1146,6 +1164,7 @@
 	struct nfs41_server_owner	*server_owner;
 	struct nfs41_server_scope	*server_scope;
 	struct nfs41_impl_id		*impl_id;
+	struct nfs41_state_protection	state_protect;
 };
 
 struct nfs41_create_session_args {