SUNRPC: Initialize rpc_rqst outside of xprt->reserve_lock

alloc_slot is a transport-specific op, but initializing an rpc_rqst
is common to all transports. In addition, the only part of initial-
izing an rpc_rqst that needs serialization is getting a fresh XID.

Move rpc_rqst initialization to common code in preparation for
adding a transport-specific alloc_slot to xprtrdma.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

include/linux/sunrpc/xprt.h

@@ -324,6 +324,7 @@ struct xprt_class {
 struct rpc_xprt		*xprt_create_transport(struct xprt_create *args);
 void			xprt_connect(struct rpc_task *task);
 void			xprt_reserve(struct rpc_task *task);
+void			xprt_request_init(struct rpc_task *task);
 void			xprt_retry_reserve(struct rpc_task *task);
 int			xprt_reserve_xprt(struct rpc_xprt *xprt, struct rpc_task *task);
 int			xprt_reserve_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task);

net/sunrpc/clnt.c

@@ -1546,6 +1546,7 @@ call_reserveresult(struct rpc_task *task)
 	task->tk_status = 0;
 	if (status >= 0) {
 		if (task->tk_rqstp) {
+			xprt_request_init(task);
 			task->tk_action = call_refresh;
 			return;
 		}

net/sunrpc/xprt.c

@@ -66,7 +66,7 @@
  * Local functions
  */
 static void	 xprt_init(struct rpc_xprt *xprt, struct net *net);
-static void	xprt_request_init(struct rpc_task *, struct rpc_xprt *);
+static __be32	xprt_alloc_xid(struct rpc_xprt *xprt);
 static void	xprt_connect_status(struct rpc_task *task);
 static int      __xprt_get_cong(struct rpc_xprt *, struct rpc_task *);
 static void     __xprt_put_cong(struct rpc_xprt *, struct rpc_rqst *);
@@ -987,6 +987,8 @@ bool xprt_prepare_transmit(struct rpc_task *task)
 		task->tk_status = -EAGAIN;
 		goto out_unlock;
 	}
+	if (!bc_prealloc(req) && !req->rq_xmit_bytes_sent)
+		req->rq_xid = xprt_alloc_xid(xprt);
 	ret = true;
 out_unlock:
 	spin_unlock_bh(&xprt->transport_lock);
@@ -1163,10 +1165,10 @@ void xprt_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
 out_init_req:
 	xprt->stat.max_slots = max_t(unsigned int, xprt->stat.max_slots,
 				     xprt->num_reqs);
+	spin_unlock(&xprt->reserve_lock);
+
 	task->tk_status = 0;
 	task->tk_rqstp = req;
-	xprt_request_init(task, xprt);
-	spin_unlock(&xprt->reserve_lock);
 }
 EXPORT_SYMBOL_GPL(xprt_alloc_slot);
 
@@ -1303,8 +1305,9 @@ static inline void xprt_init_xid(struct rpc_xprt *xprt)
 	xprt->xid = prandom_u32();
 }
 
-static void xprt_request_init(struct rpc_task *task, struct rpc_xprt *xprt)
+void xprt_request_init(struct rpc_task *task)
 {
+	struct rpc_xprt *xprt = task->tk_xprt;
 	struct rpc_rqst	*req = task->tk_rqstp;
 
 	INIT_LIST_HEAD(&req->rq_list);
@@ -1312,7 +1315,6 @@ static void xprt_request_init(struct rpc_task *task, struct rpc_xprt *xprt)
 	req->rq_task	= task;
 	req->rq_xprt    = xprt;
 	req->rq_buffer  = NULL;
-	req->rq_xid     = xprt_alloc_xid(xprt);
 	req->rq_connect_cookie = xprt->connect_cookie - 1;
 	req->rq_bytes_sent = 0;
 	req->rq_snd_buf.len = 0;