SUNRPC: allow the caller of rpc_run_task to preallocate the struct rpc_task

Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

include/linux/sunrpc/sched.h

@@ -118,6 +118,7 @@ struct rpc_call_ops {
 };
 
 struct rpc_task_setup {
+	struct rpc_task *task;
 	struct rpc_clnt *rpc_client;
 	const struct rpc_message *rpc_message;
 	const struct rpc_call_ops *callback_ops;

net/sunrpc/sched.c

@@ -885,16 +885,20 @@ static void rpc_free_task(struct rcu_head *rcu)
  */
 struct rpc_task *rpc_new_task(const struct rpc_task_setup *setup_data)
 {
-	struct rpc_task	*task;
+	struct rpc_task	*task = setup_data->task;
+	unsigned short flags = 0;
 
+	if (task == NULL) {
 		task = rpc_alloc_task();
-	if (!task)
+		if (task == NULL)
 			goto out;
+		flags = RPC_TASK_DYNAMIC;
+	}
 
 	rpc_init_task(task, setup_data);
 
+	task->tk_flags |= flags;
 	dprintk("RPC:       allocated task %p\n", task);
-	task->tk_flags |= RPC_TASK_DYNAMIC;
 out:
 	return task;
 }