[PATCH] RPC: Allow multiple RPC client programs to share the same transport

 Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
 Acked-by: Olaf Kirch <okir@suse.de>
 Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

include/linux/sunrpc/clnt.h

@@ -114,6 +114,8 @@ struct rpc_clnt *rpc_create_client(struct rpc_xprt *xprt, char *servname,
 struct rpc_clnt *rpc_new_client(struct rpc_xprt *xprt, char *servname,
 				struct rpc_program *info,
 				u32 version, rpc_authflavor_t authflavor);
+struct rpc_clnt	*rpc_bind_new_program(struct rpc_clnt *,
+				struct rpc_program *, int);
 struct rpc_clnt *rpc_clone_client(struct rpc_clnt *);
 int		rpc_shutdown_client(struct rpc_clnt *);
 int		rpc_destroy_client(struct rpc_clnt *);

net/sunrpc/clnt.c

@@ -241,6 +241,8 @@ rpc_clone_client(struct rpc_clnt *clnt)
 	rpc_init_rtt(&new->cl_rtt_default, clnt->cl_xprt->timeout.to_initval);
 	if (new->cl_auth)
 		atomic_inc(&new->cl_auth->au_count);
+	new->cl_pmap		= &new->cl_pmap_default;
+	rpc_init_wait_queue(&new->cl_pmap_default.pm_bindwait, "bindwait");
 	return new;
 out_no_clnt:
 	printk(KERN_INFO "RPC: out of memory in %s\n", __FUNCTION__);
@@ -329,6 +331,44 @@ rpc_release_client(struct rpc_clnt *clnt)
 		rpc_destroy_client(clnt);
 }
 
+/**
+ * rpc_bind_new_program - bind a new RPC program to an existing client
+ * @old - old rpc_client
+ * @program - rpc program to set
+ * @vers - rpc program version
+ *
+ * Clones the rpc client and sets up a new RPC program. This is mainly
+ * of use for enabling different RPC programs to share the same transport.
+ * The Sun NFSv2/v3 ACL protocol can do this.
+ */
+struct rpc_clnt *rpc_bind_new_program(struct rpc_clnt *old,
+				      struct rpc_program *program,
+				      int vers)
+{
+	struct rpc_clnt *clnt;
+	struct rpc_version *version;
+	int err;
+
+	BUG_ON(vers >= program->nrvers || !program->version[vers]);
+	version = program->version[vers];
+	clnt = rpc_clone_client(old);
+	if (IS_ERR(clnt))
+		goto out;
+	clnt->cl_procinfo = version->procs;
+	clnt->cl_maxproc  = version->nrprocs;
+	clnt->cl_protname = program->name;
+	clnt->cl_prog     = program->number;
+	clnt->cl_vers     = version->number;
+	clnt->cl_stats    = program->stats;
+	err = rpc_ping(clnt, RPC_TASK_SOFT|RPC_TASK_NOINTR);
+	if (err != 0) {
+		rpc_shutdown_client(clnt);
+		clnt = ERR_PTR(err);
+	}
+out:	
+	return clnt;
+}
+
 /*
  * Default callback for async RPC calls
  */

net/sunrpc/pmap_clnt.c

@@ -53,6 +53,9 @@ rpc_getport(struct rpc_task *task, struct rpc_clnt *clnt)
 			task->tk_pid, clnt->cl_server,
 			map->pm_prog, map->pm_vers, map->pm_prot);
 
+	/* Autobind on cloned rpc clients is discouraged */
+	BUG_ON(clnt->cl_parent != clnt);
+
 	spin_lock(&pmap_lock);
 	if (map->pm_binding) {
 		rpc_sleep_on(&map->pm_bindwait, task, NULL, NULL);

net/sunrpc/sunrpc_syms.c

@@ -42,6 +42,7 @@ EXPORT_SYMBOL(rpc_release_task);
 /* RPC client functions */
 EXPORT_SYMBOL(rpc_create_client);
 EXPORT_SYMBOL(rpc_clone_client);
+EXPORT_SYMBOL(rpc_bind_new_program);
 EXPORT_SYMBOL(rpc_destroy_client);
 EXPORT_SYMBOL(rpc_shutdown_client);
 EXPORT_SYMBOL(rpc_release_client);