SUNRPC: Add a helper to return the transport identifier given a netid

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

include/linux/sunrpc/xprt.h

@@ -386,6 +386,7 @@ xprt_disable_swap(struct rpc_xprt *xprt)
 int			xprt_register_transport(struct xprt_class *type);
 int			xprt_unregister_transport(struct xprt_class *type);
 int			xprt_load_transport(const char *);
+int			xprt_find_transport_ident(const char *);
 void			xprt_wait_for_reply_request_def(struct rpc_task *task);
 void			xprt_wait_for_reply_request_rtt(struct rpc_task *task);
 void			xprt_wake_pending_tasks(struct rpc_xprt *xprt, int status);

net/sunrpc/xprt.c

@@ -219,22 +219,39 @@ xprt_class_find_by_netid(const char *netid)
 }
 
 /**
- * xprt_load_transport - load a transport implementation
+ * xprt_find_transport_ident - convert a netid into a transport identifier
  * @netid: transport to load
  *
  * Returns:
- * 0:		transport successfully loaded
+ * > 0:		transport identifier
  * -ENOENT:	transport module not available
  */
-int xprt_load_transport(const char *netid)
+int xprt_find_transport_ident(const char *netid)
 {
 	const struct xprt_class *t;
+	int ret;
 
 	t = xprt_class_find_by_netid(netid);
 	if (!t)
 		return -ENOENT;
+	ret = t->ident;
 	xprt_class_release(t);
-	return 0;
+	return ret;
+}
+EXPORT_SYMBOL_GPL(xprt_find_transport_ident);
+
+/**
+ * xprt_load_transport - load a transport implementation
+ * @netid: transport to load
+ *
+ * Returns:
+ * 0:		transport successfully loaded
+ * -ENOENT:	transport module not available
+ */
+int xprt_load_transport(const char *netid)
+{
+	int ret = xprt_find_transport_ident(netid);
+	return ret < 0 ? ret : 0;
 }
 EXPORT_SYMBOL_GPL(xprt_load_transport);