SUNRPC: Add a convenient default for the hostname when calling rpc_create()

A couple of callers just use a stringified IP address for the rpc client's
hostname.  Move the logic for constructing this into rpc_create(), so it can
be shared.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/mount_clnt.c

@@ -28,8 +28,7 @@
 #define MOUNT_UMNT		3
  */
 
-static struct rpc_clnt *	mnt_create(char *, struct sockaddr_in *,
-								int, int);
+static struct rpc_clnt *	mnt_create(struct sockaddr_in *, int, int);
 static struct rpc_program	mnt_program;
 
 struct mnt_fhstatus {
@@ -52,14 +51,12 @@ nfsroot_mount(struct sockaddr_in *addr, char *path, struct nfs_fh *fh,
 		.rpc_argp	= path,
 		.rpc_resp	= &result,
 	};
-	char			hostname[32];
 	int			status;
 
 	dprintk("NFS:      nfs_mount(%08x:%s)\n",
 			(unsigned)ntohl(addr->sin_addr.s_addr), path);
 
-	sprintf(hostname, "%u.%u.%u.%u", NIPQUAD(addr->sin_addr.s_addr));
-	mnt_clnt = mnt_create(hostname, addr, version, protocol);
+	mnt_clnt = mnt_create(addr, version, protocol);
 	if (IS_ERR(mnt_clnt))
 		return PTR_ERR(mnt_clnt);
 
@@ -73,15 +70,13 @@ nfsroot_mount(struct sockaddr_in *addr, char *path, struct nfs_fh *fh,
 	return status < 0? status : (result.status? -EACCES : 0);
 }
 
-static struct rpc_clnt *
-mnt_create(char *hostname, struct sockaddr_in *srvaddr, int version,
+static struct rpc_clnt *mnt_create(struct sockaddr_in *srvaddr, int version,
 				   int protocol)
 {
 	struct rpc_create_args args = {
 		.protocol	= protocol,
 		.address	= (struct sockaddr *)srvaddr,
 		.addrsize	= sizeof(*srvaddr),
-		.servername	= hostname,
 		.program	= &mnt_program,
 		.version	= version,
 		.authflavor	= RPC_AUTH_UNIX,

fs/nfsd/nfs4callback.c

@@ -394,7 +394,6 @@ nfsd4_probe_callback(struct nfs4_client *clp)
 		.rpc_proc       = &nfs4_cb_procedures[NFSPROC4_CLNT_CB_NULL],
 		.rpc_argp       = clp,
 	};
-	char clientname[16];
 	int status;
 
 	if (atomic_read(&cb->cb_set))
@@ -417,11 +416,6 @@ nfsd4_probe_callback(struct nfs4_client *clp)
 	memset(program->stats, 0, sizeof(cb->cb_stat));
 	program->stats->program = program;
 
-	/* Just here to make some printk's more useful: */
-	snprintf(clientname, sizeof(clientname),
-		"%u.%u.%u.%u", NIPQUAD(addr.sin_addr));
-	args.servername = clientname;
-
 	/* Create RPC client */
 	cb->cb_client = rpc_create(&args);
 	if (IS_ERR(cb->cb_client)) {

net/sunrpc/clnt.c

@@ -234,12 +234,25 @@ struct rpc_clnt *rpc_create(struct rpc_create_args *args)
 {
 	struct rpc_xprt *xprt;
 	struct rpc_clnt *clnt;
+	char servername[20];
 
 	xprt = xprt_create_transport(args->protocol, args->address,
 					args->addrsize, args->timeout);
 	if (IS_ERR(xprt))
 		return (struct rpc_clnt *)xprt;
 
+	/*
+	 * If the caller chooses not to specify a hostname, whip
+	 * up a string representation of the passed-in address.
+	 */
+	if (args->servername == NULL) {
+		struct sockaddr_in *addr =
+					(struct sockaddr_in *) &args->address;
+		snprintf(servername, sizeof(servername), NIPQUAD_FMT,
+			NIPQUAD(addr->sin_addr.s_addr));
+		args->servername = servername;
+	}
+
 	/*
 	 * By default, kernel RPC client connects from a reserved port.
 	 * CAP_NET_BIND_SERVICE will not be set for unprivileged requesters,