sunrpc: add xprt id

This adds a unique identifier for a sunrpc transport in sysfs, which is
similarly managed to the unique IDs of clients.

Signed-off-by: Dan Aloni <dan@kernelim.com>

include/linux/sunrpc/xprt.h

@@ -185,6 +185,7 @@ enum xprt_transports {
 struct rpc_xprt {
 	struct kref		kref;		/* Reference count */
 	const struct rpc_xprt_ops *ops;		/* transport methods */
+	unsigned int		id;		/* transport id */
 
 	const struct rpc_timeout *timeout;	/* timeout parms */
 	struct sockaddr_storage	addr;		/* server address */
@@ -368,6 +369,7 @@ struct rpc_xprt *	xprt_alloc(struct net *net, size_t size,
 				unsigned int num_prealloc,
 				unsigned int max_req);
 void			xprt_free(struct rpc_xprt *);
+void			xprt_cleanup_ids(void);
 
 static inline int
 xprt_enable_swap(struct rpc_xprt *xprt)

net/sunrpc/sunrpc_syms.c

@@ -133,6 +133,7 @@ cleanup_sunrpc(void)
 {
 	rpc_sysfs_exit();
 	rpc_cleanup_clids();
+	xprt_cleanup_ids();
 	rpcauth_remove_module();
 	cleanup_socket_xprt();
 	svc_cleanup_xprt_sock();

net/sunrpc/xprt.c

@@ -1722,6 +1722,30 @@ static void xprt_free_all_slots(struct rpc_xprt *xprt)
 	}
 }
 
+static DEFINE_IDA(rpc_xprt_ids);
+
+void xprt_cleanup_ids(void)
+{
+	ida_destroy(&rpc_xprt_ids);
+}
+
+static int xprt_alloc_id(struct rpc_xprt *xprt)
+{
+	int id;
+
+	id = ida_simple_get(&rpc_xprt_ids, 0, 0, GFP_KERNEL);
+	if (id < 0)
+		return id;
+
+	xprt->id = id;
+	return 0;
+}
+
+static void xprt_free_id(struct rpc_xprt *xprt)
+{
+	ida_simple_remove(&rpc_xprt_ids, xprt->id);
+}
+
 struct rpc_xprt *xprt_alloc(struct net *net, size_t size,
 		unsigned int num_prealloc,
 		unsigned int max_alloc)
@@ -1734,6 +1758,7 @@ struct rpc_xprt *xprt_alloc(struct net *net, size_t size,
 	if (xprt == NULL)
 		goto out;
 
+	xprt_alloc_id(xprt);
 	xprt_init(xprt, net);
 
 	for (i = 0; i < num_prealloc; i++) {
@@ -1762,6 +1787,7 @@ void xprt_free(struct rpc_xprt *xprt)
 {
 	put_net(xprt->xprt_net);
 	xprt_free_all_slots(xprt);
+	xprt_free_id(xprt);
 	kfree_rcu(xprt, rcu);
 }
 EXPORT_SYMBOL_GPL(xprt_free);