[PATCH] RPC: clean up after nocong was removed

 Clean-up:  Move some macros that are specific to the Van Jacobson
 implementation into xprt.c.  Get rid of the cong_wait field in
 rpc_xprt, which is no longer used.  Get rid of xprt_clear_backlog.

 Test-plan:
 Compile with CONFIG_NFS enabled.
Signed-off-by: Chuck Lever <cel@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

include/linux/sunrpc/xprt.h

@@ -15,20 +15,6 @@
 #include <linux/sunrpc/sched.h>
 #include <linux/sunrpc/xdr.h>
 
-/*
- * The transport code maintains an estimate on the maximum number of out-
- * standing RPC requests, using a smoothed version of the congestion
- * avoidance implemented in 44BSD. This is basically the Van Jacobson
- * congestion algorithm: If a retransmit occurs, the congestion window is
- * halved; otherwise, it is incremented by 1/cwnd when
- *
- *	-	a reply is received and
- *	-	a full number of requests are outstanding and
- *	-	the congestion window hasn't been updated recently.
- *
- * Upper procedures may check whether a request would block waiting for
- * a free RPC slot by using the RPC_CONGESTED() macro.
- */
 extern unsigned int xprt_udp_slot_table_entries;
 extern unsigned int xprt_tcp_slot_table_entries;
 
@@ -36,12 +22,6 @@ extern unsigned int xprt_tcp_slot_table_entries;
 #define RPC_DEF_SLOT_TABLE	(16U)
 #define RPC_MAX_SLOT_TABLE	(128U)
 
-#define RPC_CWNDSHIFT		(8U)
-#define RPC_CWNDSCALE		(1U << RPC_CWNDSHIFT)
-#define RPC_INITCWND		RPC_CWNDSCALE
-#define RPC_MAXCWND(xprt)	((xprt)->max_reqs << RPC_CWNDSHIFT)
-#define RPCXPRT_CONGESTED(xprt) ((xprt)->cong >= (xprt)->cwnd)
-
 /* Default timeout values */
 #define RPC_MAX_UDP_TIMEOUT	(60*HZ)
 #define RPC_MAX_TCP_TIMEOUT	(600*HZ)
@@ -213,8 +193,6 @@ struct rpc_xprt {
 	void			(*old_data_ready)(struct sock *, int);
 	void			(*old_state_change)(struct sock *);
 	void			(*old_write_space)(struct sock *);
-
-	wait_queue_head_t	cong_wait;
 };
 
 #define XPRT_LAST_FRAG		(1 << 0)

net/sunrpc/xprt.c

@@ -62,7 +62,23 @@ static inline void	do_xprt_reserve(struct rpc_task *);
 static void	xprt_connect_status(struct rpc_task *task);
 static int      __xprt_get_cong(struct rpc_xprt *, struct rpc_task *);
 
-static int	xprt_clear_backlog(struct rpc_xprt *xprt);
+/*
+ * The transport code maintains an estimate on the maximum number of out-
+ * standing RPC requests, using a smoothed version of the congestion
+ * avoidance implemented in 44BSD. This is basically the Van Jacobson
+ * congestion algorithm: If a retransmit occurs, the congestion window is
+ * halved; otherwise, it is incremented by 1/cwnd when
+ *
+ *	-	a reply is received and
+ *	-	a full number of requests are outstanding and
+ *	-	the congestion window hasn't been updated recently.
+ */
+#define RPC_CWNDSHIFT		(8U)
+#define RPC_CWNDSCALE		(1U << RPC_CWNDSHIFT)
+#define RPC_INITCWND		RPC_CWNDSCALE
+#define RPC_MAXCWND(xprt)	((xprt)->max_reqs << RPC_CWNDSHIFT)
+
+#define RPCXPRT_CONGESTED(xprt) ((xprt)->cong >= (xprt)->cwnd)
 
 /**
  * xprt_reserve_xprt - serialize write access to transports
@@ -850,7 +866,7 @@ void xprt_release(struct rpc_task *task)
 
 	spin_lock(&xprt->reserve_lock);
 	list_add(&req->rq_list, &xprt->free);
-	xprt_clear_backlog(xprt);
+	rpc_wake_up_next(&xprt->backlog);
 	spin_unlock(&xprt->reserve_lock);
 }
 
@@ -902,7 +918,6 @@ static struct rpc_xprt *xprt_setup(int proto, struct sockaddr_in *ap, struct rpc
 
 	spin_lock_init(&xprt->transport_lock);
 	spin_lock_init(&xprt->reserve_lock);
-	init_waitqueue_head(&xprt->cong_wait);
 
 	INIT_LIST_HEAD(&xprt->free);
 	INIT_LIST_HEAD(&xprt->recv);
@@ -911,6 +926,7 @@ static struct rpc_xprt *xprt_setup(int proto, struct sockaddr_in *ap, struct rpc
 	xprt->timer.function = xprt_init_autodisconnect;
 	xprt->timer.data = (unsigned long) xprt;
 	xprt->last_used = jiffies;
+	xprt->cwnd = RPC_INITCWND;
 
 	rpc_init_wait_queue(&xprt->pending, "xprt_pending");
 	rpc_init_wait_queue(&xprt->sending, "xprt_sending");
@@ -955,16 +971,9 @@ static void xprt_shutdown(struct rpc_xprt *xprt)
 	rpc_wake_up(&xprt->resend);
 	xprt_wake_pending_tasks(xprt, -EIO);
 	rpc_wake_up(&xprt->backlog);
-	wake_up(&xprt->cong_wait);
 	del_timer_sync(&xprt->timer);
 }
 
-static int xprt_clear_backlog(struct rpc_xprt *xprt) {
-	rpc_wake_up_next(&xprt->backlog);
-	wake_up(&xprt->cong_wait);
-	return 1;
-}
-
 /**
  * xprt_destroy - destroy an RPC transport, killing off all requests.
  * @xprt: transport to destroy

net/sunrpc/xprtsock.c

@@ -1100,7 +1100,6 @@ int xs_setup_udp(struct rpc_xprt *xprt, struct rpc_timeout *to)
 	xprt->prot = IPPROTO_UDP;
 	xprt->port = XS_MAX_RESVPORT;
 	xprt->tsh_size = 0;
-	xprt->cwnd = RPC_INITCWND;
 	xprt->resvport = capable(CAP_NET_BIND_SERVICE) ? 1 : 0;
 	/* XXX: header size can vary due to auth type, IPv6, etc. */
 	xprt->max_payload = (1U << 16) - (MAX_HEADER << 3);
@@ -1139,7 +1138,6 @@ int xs_setup_tcp(struct rpc_xprt *xprt, struct rpc_timeout *to)
 	xprt->prot = IPPROTO_TCP;
 	xprt->port = XS_MAX_RESVPORT;
 	xprt->tsh_size = sizeof(rpc_fraghdr) / sizeof(u32);
-	xprt->cwnd = RPC_MAXCWND(xprt);
 	xprt->resvport = capable(CAP_NET_BIND_SERVICE) ? 1 : 0;
 	xprt->max_payload = RPC_MAX_FRAGMENT_SIZE;