Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/teigland/dlm

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/teigland/dlm:
  dlm: sanitize work_start() in lowcomms.c
  dlm: reduce cond_resched during send
  dlm: use TCP_NODELAY
  dlm: Use cmwq for send and receive workqueues
  dlm: Handle application limited situations properly.

fs/dlm/lowcomms.c

@@ -63,6 +63,9 @@
 #define NEEDED_RMEM (4*1024*1024)
 #define CONN_HASH_SIZE 32
 
+/* Number of messages to send before rescheduling */
+#define MAX_SEND_MSG_COUNT 25
+
 struct cbuf {
 	unsigned int base;
 	unsigned int len;
@@ -108,6 +111,7 @@ struct connection {
 #define CF_INIT_PENDING 4
 #define CF_IS_OTHERCON 5
 #define CF_CLOSE 6
+#define CF_APP_LIMITED 7
 	struct list_head writequeue;  /* List of outgoing writequeue_entries */
 	spinlock_t writequeue_lock;
 	int (*rx_action) (struct connection *);	/* What to do when active */
@@ -295,7 +299,17 @@ static void lowcomms_write_space(struct sock *sk)
 {
 	struct connection *con = sock2con(sk);
 
-	if (con && !test_and_set_bit(CF_WRITE_PENDING, &con->flags))
+	if (!con)
+		return;
+
+	clear_bit(SOCK_NOSPACE, &con->sock->flags);
+
+	if (test_and_clear_bit(CF_APP_LIMITED, &con->flags)) {
+		con->sock->sk->sk_write_pending--;
+		clear_bit(SOCK_ASYNC_NOSPACE, &con->sock->flags);
+	}
+
+	if (!test_and_set_bit(CF_WRITE_PENDING, &con->flags))
 		queue_work(send_workqueue, &con->swork);
 }
 
@@ -915,6 +929,7 @@ static void tcp_connect_to_sock(struct connection *con)
 	struct sockaddr_storage saddr, src_addr;
 	int addr_len;
 	struct socket *sock = NULL;
+	int one = 1;
 
 	if (con->nodeid == 0) {
 		log_print("attempt to connect sock 0 foiled");
@@ -960,6 +975,11 @@ static void tcp_connect_to_sock(struct connection *con)
 	make_sockaddr(&saddr, dlm_config.ci_tcp_port, &addr_len);
 
 	log_print("connecting to %d", con->nodeid);
+
+	/* Turn off Nagle's algorithm */
+	kernel_setsockopt(sock, SOL_TCP, TCP_NODELAY, (char *)&one,
+			  sizeof(one));
+
 	result =
 		sock->ops->connect(sock, (struct sockaddr *)&saddr, addr_len,
 				   O_NONBLOCK);
@@ -1011,6 +1031,10 @@ static struct socket *tcp_create_listen_sock(struct connection *con,
 		goto create_out;
 	}
 
+	/* Turn off Nagle's algorithm */
+	kernel_setsockopt(sock, SOL_TCP, TCP_NODELAY, (char *)&one,
+			  sizeof(one));
+
 	result = kernel_setsockopt(sock, SOL_SOCKET, SO_REUSEADDR,
 				   (char *)&one, sizeof(one));
 
@@ -1297,6 +1321,7 @@ static void send_to_sock(struct connection *con)
 	const int msg_flags = MSG_DONTWAIT | MSG_NOSIGNAL;
 	struct writequeue_entry *e;
 	int len, offset;
+	int count = 0;
 
 	mutex_lock(&con->sock_mutex);
 	if (con->sock == NULL)
@@ -1319,14 +1344,27 @@ static void send_to_sock(struct connection *con)
 			ret = kernel_sendpage(con->sock, e->page, offset, len,
 					      msg_flags);
 			if (ret == -EAGAIN || ret == 0) {
+				if (ret == -EAGAIN &&
+				    test_bit(SOCK_ASYNC_NOSPACE, &con->sock->flags) &&
+				    !test_and_set_bit(CF_APP_LIMITED, &con->flags)) {
+					/* Notify TCP that we're limited by the
+					 * application window size.
+					 */
+					set_bit(SOCK_NOSPACE, &con->sock->flags);
+					con->sock->sk->sk_write_pending++;
+				}
 				cond_resched();
 				goto out;
 			}
 			if (ret <= 0)
 				goto send_error;
 		}
-			/* Don't starve people filling buffers */
+
+		/* Don't starve people filling buffers */
+		if (++count >= MAX_SEND_MSG_COUNT) {
 			cond_resched();
+			count = 0;
+		}
 
 		spin_lock(&con->writequeue_lock);
 		e->offset += ret;
@@ -1430,20 +1468,19 @@ static void work_stop(void)
 
 static int work_start(void)
 {
-	int error;
-	recv_workqueue = create_workqueue("dlm_recv");
-	error = IS_ERR(recv_workqueue);
-	if (error) {
-		log_print("can't start dlm_recv %d", error);
-		return error;
+	recv_workqueue = alloc_workqueue("dlm_recv", WQ_MEM_RECLAIM |
+					 WQ_HIGHPRI | WQ_FREEZEABLE, 0);
+	if (!recv_workqueue) {
+		log_print("can't start dlm_recv");
+		return -ENOMEM;
 	}
 
-	send_workqueue = create_singlethread_workqueue("dlm_send");
-	error = IS_ERR(send_workqueue);
-	if (error) {
-		log_print("can't start dlm_send %d", error);
+	send_workqueue = alloc_workqueue("dlm_send", WQ_MEM_RECLAIM |
+					 WQ_HIGHPRI | WQ_FREEZEABLE, 0);
+	if (!send_workqueue) {
+		log_print("can't start dlm_send");
 		destroy_workqueue(recv_workqueue);
-		return error;
+		return -ENOMEM;
 	}
 
 	return 0;