sunrpc: add a symlink from rpc-client directory to the xprt_switch

An rpc client uses a transport switch and one ore more transports
associated with that switch. Since transports are shared among
rpc clients, create a symlink into the xprt_switch directory
instead of duplicating entries under each rpc client.
Signed-off-by: Olga Kornievskaia <kolga@netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

net/sunrpc/clnt.c

@@ -301,7 +301,6 @@ static int rpc_client_register(struct rpc_clnt *clnt,
 	int err;
 
 	rpc_clnt_debugfs_register(clnt);
-	rpc_sysfs_client_setup(clnt, net);
 
 	pipefs_sb = rpc_get_sb_net(net);
 	if (pipefs_sb) {
@@ -426,6 +425,7 @@ static struct rpc_clnt * rpc_new_client(const struct rpc_create_args *args,
 	/* save the nodename */
 	rpc_clnt_set_nodename(clnt, nodename);
 
+	rpc_sysfs_client_setup(clnt, xps, rpc_net_ns(clnt));
 	err = rpc_client_register(clnt, args->authflavor, args->client_name);
 	if (err)
 		goto out_no_path;

net/sunrpc/sysfs.c

@@ -151,14 +151,29 @@ rpc_sysfs_xprt_switch_alloc(struct kobject *parent,
 	return NULL;
 }
 
-void rpc_sysfs_client_setup(struct rpc_clnt *clnt, struct net *net)
+void rpc_sysfs_client_setup(struct rpc_clnt *clnt,
+			    struct rpc_xprt_switch *xprt_switch,
+			    struct net *net)
 {
 	struct rpc_sysfs_client *rpc_client;
 
-	rpc_client = rpc_sysfs_client_alloc(rpc_sunrpc_client_kobj, net, clnt->cl_clid);
+	rpc_client = rpc_sysfs_client_alloc(rpc_sunrpc_client_kobj,
+					    net, clnt->cl_clid);
 	if (rpc_client) {
+		char name[] = "switch";
+		struct rpc_sysfs_xprt_switch *xswitch =
+			(struct rpc_sysfs_xprt_switch *)xprt_switch->xps_sysfs;
+		int ret;
+
 		clnt->cl_sysfs = rpc_client;
+		rpc_client->clnt = clnt;
+		rpc_client->xprt_switch = xprt_switch;
 		kobject_uevent(&rpc_client->kobject, KOBJ_ADD);
+		ret = sysfs_create_link_nowarn(&rpc_client->kobject,
+					       &xswitch->kobject, name);
+		if (ret)
+			pr_warn("can't create link to %s in sysfs (%d)\n",
+				name, ret);
 	}
 }
 
@@ -189,6 +204,9 @@ void rpc_sysfs_client_destroy(struct rpc_clnt *clnt)
 	struct rpc_sysfs_client *rpc_client = clnt->cl_sysfs;
 
 	if (rpc_client) {
+		char name[] = "switch";
+
+		sysfs_remove_link(&rpc_client->kobject, name);
 		kobject_uevent(&rpc_client->kobject, KOBJ_REMOVE);
 		kobject_del(&rpc_client->kobject);
 		kobject_put(&rpc_client->kobject);

net/sunrpc/sysfs.h

@@ -8,6 +8,8 @@
 struct rpc_sysfs_client {
 	struct kobject kobject;
 	struct net *net;
+	struct rpc_clnt *clnt;
+	struct rpc_xprt_switch *xprt_switch;
 };
 
 struct rpc_sysfs_xprt_switch {
@@ -20,7 +22,9 @@ struct rpc_sysfs_xprt_switch {
 int rpc_sysfs_init(void);
 void rpc_sysfs_exit(void);
 
-void rpc_sysfs_client_setup(struct rpc_clnt *clnt, struct net *net);
+void rpc_sysfs_client_setup(struct rpc_clnt *clnt,
+			    struct rpc_xprt_switch *xprt_switch,
+			    struct net *net);
 void rpc_sysfs_client_destroy(struct rpc_clnt *clnt);
 void rpc_sysfs_xprt_switch_setup(struct rpc_xprt_switch *xprt_switch,
 				 struct rpc_xprt *xprt, gfp_t gfp_flags);