SUNRPC: Introduce transport switch callout for pluggable rpcbind

Introduce a clean transport switch API for plugging in different types of
rpcbind mechanisms.  For instance, rpcbind can cleanly replace the
existing portmapper client, or a transport can choose to implement RPC
binding any way it likes.

Test plan:
Destructive testing (unplugging the network temporarily).  Connectathon
with UDP and TCP.  NFSv2/3 and NFSv4 mounting should be carefully checked.
Probably need to rig a server where certain services aren't running, or
that returns an error for some typical operation.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

3 files changed, 5 insertions, 4 deletions

diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index cee504162a3f..d003c2f5688f 100644
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -774,7 +774,6 @@ call_encode(struct rpc_task *task)
 static void
 call_bind(struct rpc_task *task)
 {
-        struct rpc_clnt *clnt = task->tk_client;
         struct rpc_xprt *xprt = task->tk_xprt;
 
         dprintk("RPC: %4d call_bind (status %d)\n",
@@ -784,7 +783,7 @@ call_bind(struct rpc_task *task)
         if (!xprt_bound(xprt)) {
                 task->tk_action = call_bind_status;
                 task->tk_timeout = xprt->bind_timeout;
-                rpc_getport(task, clnt);
+                xprt->ops->rpcbind(task);
         }
 }
 
diff --git a/net/sunrpc/pmap_clnt.c b/net/sunrpc/pmap_clnt.c
index 0efcbf1302a2..f7b279a63baa 100644
--- a/net/sunrpc/pmap_clnt.c
+++ b/net/sunrpc/pmap_clnt.c
@@ -81,13 +81,13 @@ static inline void pmap_wake_portmap_waiters(struct rpc_xprt *xprt)
 /**
  * rpc_getport - obtain the port for a given RPC service on a given host
  * @task: task that is waiting for portmapper request
- * @clnt: controlling rpc_clnt
  *
  * This one can be called for an ongoing RPC request, and can be used in
  * an async (rpciod) context.
  */
-void rpc_getport(struct rpc_task *task, struct rpc_clnt *clnt)
+void rpc_getport(struct rpc_task *task)
 {
+        struct rpc_clnt *clnt = task->tk_client;
         struct rpc_xprt *xprt = task->tk_xprt;
         struct sockaddr_in *sap = &xprt->addr;
         struct portmap_args *map;
diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index 123ac1e5ba15..4c98b89a5b48 100644
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -1262,6 +1262,7 @@ static struct rpc_xprt_ops xs_udp_ops = {
         .set_buffer_size        = xs_udp_set_buffer_size,
         .reserve_xprt           = xprt_reserve_xprt_cong,
         .release_xprt           = xprt_release_xprt_cong,
+        .rpcbind                = rpc_getport,
         .set_port               = xs_set_port,
         .connect                = xs_connect,
         .buf_alloc              = rpc_malloc,
@@ -1278,6 +1279,7 @@ static struct rpc_xprt_ops xs_udp_ops = {
 static struct rpc_xprt_ops xs_tcp_ops = {
         .reserve_xprt           = xprt_reserve_xprt,
         .release_xprt           = xs_tcp_release_xprt,
+        .rpcbind                = rpc_getport,
         .set_port               = xs_set_port,
         .connect                = xs_connect,
         .buf_alloc              = rpc_malloc,