SUNRPC: Eliminate task->tk_xprt accesses that bypass rcu_dereference()

tk_xprt is just a shortcut for tk_client->cl_xprt, however cl_xprt is
defined as an __rcu variable. Replace dereferences of tk_xprt with
non-rcu dereferences where it is safe to do so.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/net/sunrpc/xprtrdma/transport.c b/net/sunrpc/xprtrdma/transport.c
index c9aa7a3..b357c52 100644
--- a/net/sunrpc/xprtrdma/transport.c
+++ b/net/sunrpc/xprtrdma/transport.c
@@ -475,7 +475,7 @@
 static void *
 xprt_rdma_allocate(struct rpc_task *task, size_t size)
 {
-	struct rpc_xprt *xprt = task->tk_xprt;
+	struct rpc_xprt *xprt = task->tk_rqstp->rq_xprt;
 	struct rpcrdma_req *req, *nreq;
 
 	req = rpcrdma_buffer_get(&rpcx_to_rdmax(xprt)->rx_buf);
@@ -627,7 +627,7 @@
 xprt_rdma_send_request(struct rpc_task *task)
 {
 	struct rpc_rqst *rqst = task->tk_rqstp;
-	struct rpc_xprt *xprt = task->tk_xprt;
+	struct rpc_xprt *xprt = rqst->rq_xprt;
 	struct rpcrdma_req *req = rpcr_to_rdmar(rqst);
 	struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);