NFS: send state management on a single connection.

With NFSv4.1, different network connections need to be explicitly
bound to a session.  During session startup, this is not possible
so only a single connection must be used for session startup.

So add a task flag to disable the default round-robin choice of
connections (when nconnect > 1) and force the use of a single
connection.
Then use that flag on all requests for session management - for
consistence, include NFSv4.0 management (SETCLIENTID) and session
destruction

Reported-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

1 files changed, 23 insertions, 1 deletions

diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index b6aca8cb5ae6..d599fab8adcb 100644
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -995,6 +995,24 @@ rpc_task_get_xprt(struct rpc_clnt *clnt)
         return xprt;
 }
 
+static struct rpc_xprt *
+rpc_task_get_first_xprt(struct rpc_clnt *clnt)
+{
+        struct rpc_xprt_switch *xps;
+        struct rpc_xprt *xprt;
+
+        rcu_read_lock();
+        xprt = xprt_get(rcu_dereference(clnt->cl_xprt));
+        if (xprt) {
+                atomic_long_inc(&xprt->queuelen);
+                xps = rcu_dereference(clnt->cl_xpi.xpi_xpswitch);
+                atomic_long_inc(&xps->xps_queuelen);
+        }
+        rcu_read_unlock();
+
+        return xprt;
+}
+
 static void
 rpc_task_release_xprt(struct rpc_clnt *clnt, struct rpc_xprt *xprt)
 {
@@ -1042,7 +1060,11 @@ void rpc_task_release_client(struct rpc_task *task)
 static
 void rpc_task_set_transport(struct rpc_task *task, struct rpc_clnt *clnt)
 {
-        if (!task->tk_xprt)
+        if (task->tk_xprt)
+                return;
+        if (task->tk_flags & RPC_TASK_NO_ROUND_ROBIN)
+                task->tk_xprt = rpc_task_get_first_xprt(clnt);
+        else
                 task->tk_xprt = rpc_task_get_xprt(clnt);
 }