SUNRPC: introduce rpcbind: replacement for in-kernel portmapper

Introduce a replacement for the in-kernel portmapper client that supports
all 3 versions of the rpcbind protocol.  This code is not used yet.

Original code by Groupe Bull updated for the latest kernel, with multiple
bug fixes.

Note that rpcb_clnt.c does not yet support registering via versions 3 and
4 of the rpcbind protocol.  That is planned for a later patch.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

include/linux/sunrpc/clnt.h

@@ -124,6 +124,8 @@ int		rpc_destroy_client(struct rpc_clnt *);
 void		rpc_release_client(struct rpc_clnt *);
 void		rpc_getport(struct rpc_task *);
 int		rpc_register(u32, u32, int, unsigned short, int *);
+int		rpcb_register(u32, u32, int, unsigned short, int *);
+void		rpcb_getport(struct rpc_task *);
 
 void		rpc_call_setup(struct rpc_task *, struct rpc_message *, int);
 
@@ -146,6 +148,7 @@ char *		rpc_peeraddr2str(struct rpc_clnt *, enum rpc_display_format_t);
  * Helper function for NFSroot support
  */
 int		rpc_getport_external(struct sockaddr_in *, __u32, __u32, int);
+int		rpcb_getport_external(struct sockaddr_in *, __u32, __u32, int);
 
 #endif /* __KERNEL__ */
 #endif /* _LINUX_SUNRPC_CLNT_H */

include/linux/sunrpc/debug.h

@@ -18,6 +18,7 @@
 #define RPCDBG_NFS		0x0008
 #define RPCDBG_AUTH		0x0010
 #define RPCDBG_PMAP		0x0020
+#define RPCDBG_BIND		0x0020
 #define RPCDBG_SCHED		0x0040
 #define RPCDBG_TRANS		0x0080
 #define RPCDBG_SVCSOCK		0x0100

include/linux/sunrpc/xprt.h

@@ -152,6 +152,7 @@ struct rpc_xprt {
 	unsigned long		state;		/* transport state */
 	unsigned char		shutdown   : 1,	/* being shut down */
 				resvport   : 1; /* use a reserved port */
+	unsigned int		bind_index;	/* bind function index */
 
 	/*
 	 * Connection of transports

net/sunrpc/Makefile

@@ -9,7 +9,7 @@ obj-$(CONFIG_SUNRPC_GSS) += auth_gss/
 sunrpc-y := clnt.o xprt.o socklib.o xprtsock.o sched.o \
 	    auth.o auth_null.o auth_unix.o \
 	    svc.o svcsock.o svcauth.o svcauth_unix.o \
-	    pmap_clnt.o timer.o xdr.o \
+	    pmap_clnt.o rpcb_clnt.o timer.o xdr.o \
 	    sunrpc_syms.o cache.o rpc_pipe.o
 sunrpc-$(CONFIG_PROC_FS) += stats.o
 sunrpc-$(CONFIG_SYSCTL) += sysctl.o