[DLM] Consolidate transport protocols

This patch consolidates the TCP & SCTP protocols for the DLM into a single file
and makes it switchable at run-time (well, at least before the DLM actually
starts up!)

For RHEL5 this patch requires Neil Horman's patch that expands the in-kernel
socket API but that has already been twice ACKed so it should be OK.

The patch adds a new lowcomms.c file that replaces the existing lowcomms-sctp.c
& lowcomms-tcp.c files.

Signed-off-By: Patrick Caulfield <pcaulfie@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

1 files changed, 0 insertions, 1006 deletions

diff --git a/fs/dlm/lowcomms-tcp.c b/fs/dlm/lowcomms-tcp.c
deleted file mode 100644
index 919e92a6aeb..00000000000
--- a/fs/dlm/lowcomms-tcp.c
+++ /dev/null
@@ -1,1006 +0,0 @@
-/******************************************************************************
-*******************************************************************************
-**
-**  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
-**  Copyright (C) 2004-2007 Red Hat, Inc.  All rights reserved.
-**
-**  This copyrighted material is made available to anyone wishing to use,
-**  modify, copy, or redistribute it subject to the terms and conditions
-**  of the GNU General Public License v.2.
-**
-*******************************************************************************
-******************************************************************************/
-
-/*
- * lowcomms.c
- *
- * This is the "low-level" comms layer.
- *
- * It is responsible for sending/receiving messages
- * from other nodes in the cluster.
- *
- * Cluster nodes are referred to by their nodeids. nodeids are
- * simply 32 bit numbers to the locking module - if they need to
- * be expanded for the cluster infrastructure then that is it's
- * responsibility. It is this layer's
- * responsibility to resolve these into IP address or
- * whatever it needs for inter-node communication.
- *
- * The comms level is two kernel threads that deal mainly with
- * the receiving of messages from other nodes and passing them
- * up to the mid-level comms layer (which understands the
- * message format) for execution by the locking core, and
- * a send thread which does all the setting up of connections
- * to remote nodes and the sending of data. Threads are not allowed
- * to send their own data because it may cause them to wait in times
- * of high load. Also, this way, the sending thread can collect together
- * messages bound for one node and send them in one block.
- *
- * I don't see any problem with the recv thread executing the locking
- * code on behalf of remote processes as the locking code is
- * short, efficient and never waits.
- *
- */
-
-
-#include <asm/ioctls.h>
-#include <net/sock.h>
-#include <net/tcp.h>
-#include <linux/pagemap.h>
-
-#include "dlm_internal.h"
-#include "lowcomms.h"
-#include "midcomms.h"
-#include "config.h"
-
-struct cbuf {
-	unsigned int base;
-	unsigned int len;
-	unsigned int mask;
-};
-
-#define NODE_INCREMENT 32
-static void cbuf_add(struct cbuf *cb, int n)
-{
-	cb->len += n;
-}
-
-static int cbuf_data(struct cbuf *cb)
-{
-	return ((cb->base + cb->len) & cb->mask);
-}
-
-static void cbuf_init(struct cbuf *cb, int size)
-{
-	cb->base = cb->len = 0;
-	cb->mask = size-1;
-}
-
-static void cbuf_eat(struct cbuf *cb, int n)
-{
-	cb->len  -= n;
-	cb->base += n;
-	cb->base &= cb->mask;
-}
-
-static bool cbuf_empty(struct cbuf *cb)
-{
-	return cb->len == 0;
-}
-
-/* Maximum number of incoming messages to process before
-   doing a cond_resched()
-*/
-#define MAX_RX_MSG_COUNT 25
-
-struct connection {
-	struct socket *sock;	/* NULL if not connected */
-	uint32_t nodeid;	/* So we know who we are in the list */
-	struct mutex sock_mutex;
-	unsigned long flags;	/* bit 1,2 = We are on the read/write lists */
-#define CF_READ_PENDING 1
-#define CF_WRITE_PENDING 2
-#define CF_CONNECT_PENDING 3
-#define CF_IS_OTHERCON 4
-	struct list_head writequeue;  /* List of outgoing writequeue_entries */
-	struct list_head listenlist;  /* List of allocated listening sockets */
-	spinlock_t writequeue_lock;
-	int (*rx_action) (struct connection *);	/* What to do when active */
-	struct page *rx_page;
-	struct cbuf cb;
-	int retries;
-#define MAX_CONNECT_RETRIES 3
-	struct connection *othercon;
-	struct work_struct rwork; /* Receive workqueue */
-	struct work_struct swork; /* Send workqueue */
-};
-#define sock2con(x) ((struct connection *)(x)->sk_user_data)
-
-/* An entry waiting to be sent */
-struct writequeue_entry {
-	struct list_head list;
-	struct page *page;
-	int offset;
-	int len;
-	int end;
-	int users;
-	struct connection *con;
-};
-
-static struct sockaddr_storage dlm_local_addr;
-
-/* Work queues */
-static struct workqueue_struct *recv_workqueue;
-static struct workqueue_struct *send_workqueue;
-
-/* An array of pointers to connections, indexed by NODEID */
-static struct connection **connections;
-static DECLARE_MUTEX(connections_lock);
-static struct kmem_cache *con_cache;
-static int conn_array_size;
-
-static void process_recv_sockets(struct work_struct *work);
-static void process_send_sockets(struct work_struct *work);
-
-static struct connection *nodeid2con(int nodeid, gfp_t allocation)
-{
-	struct connection *con = NULL;
-
-	down(&connections_lock);
-	if (nodeid >= conn_array_size) {
-		int new_size = nodeid + NODE_INCREMENT;
-		struct connection **new_conns;
-
-		new_conns = kzalloc(sizeof(struct connection *) *
-				    new_size, allocation);
-		if (!new_conns)
-			goto finish;
-
-		memcpy(new_conns, connections,  sizeof(struct connection *) * conn_array_size);
-		conn_array_size = new_size;
-		kfree(connections);
-		connections = new_conns;
-
-	}
-
-	con = connections[nodeid];
-	if (con == NULL && allocation) {
-		con = kmem_cache_zalloc(con_cache, allocation);
-		if (!con)
-			goto finish;
-
-		con->nodeid = nodeid;
-		mutex_init(&con->sock_mutex);
-		INIT_LIST_HEAD(&con->writequeue);
-		spin_lock_init(&con->writequeue_lock);
-		INIT_WORK(&con->swork, process_send_sockets);
-		INIT_WORK(&con->rwork, process_recv_sockets);
-
-		connections[nodeid] = con;
-	}
-
-finish:
-	up(&connections_lock);
-	return con;
-}
-
-/* Data available on socket or listen socket received a connect */
-static void lowcomms_data_ready(struct sock *sk, int count_unused)
-{
-	struct connection *con = sock2con(sk);
-
-	if (!test_and_set_bit(CF_READ_PENDING, &con->flags))
-		queue_work(recv_workqueue, &con->rwork);
-}
-
-static void lowcomms_write_space(struct sock *sk)
-{
-	struct connection *con = sock2con(sk);
-
-	if (!test_and_set_bit(CF_WRITE_PENDING, &con->flags))
-		queue_work(send_workqueue, &con->swork);
-}
-
-static inline void lowcomms_connect_sock(struct connection *con)
-{
-	if (!test_and_set_bit(CF_CONNECT_PENDING, &con->flags))
-		queue_work(send_workqueue, &con->swork);
-}
-
-static void lowcomms_state_change(struct sock *sk)
-{
-	if (sk->sk_state == TCP_ESTABLISHED)
-		lowcomms_write_space(sk);
-}
-
-/* Make a socket active */
-static int add_sock(struct socket *sock, struct connection *con)
-{
-	con->sock = sock;
-
-	/* Install a data_ready callback */
-	con->sock->sk->sk_data_ready = lowcomms_data_ready;
-	con->sock->sk->sk_write_space = lowcomms_write_space;
-	con->sock->sk->sk_state_change = lowcomms_state_change;
-
-	return 0;
-}
-
-/* Add the port number to an IP6 or 4 sockaddr and return the address
-   length */
-static void make_sockaddr(struct sockaddr_storage *saddr, uint16_t port,
-			  int *addr_len)
-{
-	saddr->ss_family =  dlm_local_addr.ss_family;
-	if (saddr->ss_family == AF_INET) {
-		struct sockaddr_in *in4_addr = (struct sockaddr_in *)saddr;
-		in4_addr->sin_port = cpu_to_be16(port);
-		*addr_len = sizeof(struct sockaddr_in);
-	} else {
-		struct sockaddr_in6 *in6_addr = (struct sockaddr_in6 *)saddr;
-		in6_addr->sin6_port = cpu_to_be16(port);
-		*addr_len = sizeof(struct sockaddr_in6);
-	}
-}
-
-/* Close a remote connection and tidy up */
-static void close_connection(struct connection *con, bool and_other)
-{
-	mutex_lock(&con->sock_mutex);
-
-	if (con->sock) {
-		sock_release(con->sock);
-		con->sock = NULL;
-	}
-	if (con->othercon && and_other) {
-		/* Will only re-enter once. */
-		close_connection(con->othercon, false);
-	}
-	if (con->rx_page) {
-		__free_page(con->rx_page);
-		con->rx_page = NULL;
-	}
-	con->retries = 0;
-	mutex_unlock(&con->sock_mutex);
-}
-
-/* Data received from remote end */
-static int receive_from_sock(struct connection *con)
-{
-	int ret = 0;
-	struct msghdr msg = {};
-	struct kvec iov[2];
-	unsigned len;
-	int r;
-	int call_again_soon = 0;
-	int nvec;
-
-	mutex_lock(&con->sock_mutex);
-
-	if (con->sock == NULL) {
-		ret = -EAGAIN;
-		goto out_close;
-	}
-
-	if (con->rx_page == NULL) {
-		/*
-		 * This doesn't need to be atomic, but I think it should
-		 * improve performance if it is.
-		 */
-		con->rx_page = alloc_page(GFP_ATOMIC);
-		if (con->rx_page == NULL)
-			goto out_resched;
-		cbuf_init(&con->cb, PAGE_CACHE_SIZE);
-	}
-
-	/*
-	 * iov[0] is the bit of the circular buffer between the current end
-	 * point (cb.base + cb.len) and the end of the buffer.
-	 */
-	iov[0].iov_len = con->cb.base - cbuf_data(&con->cb);
-	iov[0].iov_base = page_address(con->rx_page) + cbuf_data(&con->cb);
-	iov[1].iov_len = 0;
-	nvec = 1;
-
-	/*
-	 * iov[1] is the bit of the circular buffer between the start of the
-	 * buffer and the start of the currently used section (cb.base)
-	 */
-	if (cbuf_data(&con->cb) >= con->cb.base) {
-		iov[0].iov_len = PAGE_CACHE_SIZE - cbuf_data(&con->cb);
-		iov[1].iov_len = con->cb.base;
-		iov[1].iov_base = page_address(con->rx_page);
-		nvec = 2;
-	}
-	len = iov[0].iov_len + iov[1].iov_len;
-
-	r = ret = kernel_recvmsg(con->sock, &msg, iov, nvec, len,
-			       MSG_DONTWAIT | MSG_NOSIGNAL);
-
-	if (ret <= 0)
-		goto out_close;
-
-	if (ret == len)
-		call_again_soon = 1;
-	cbuf_add(&con->cb, ret);
-	ret = dlm_process_incoming_buffer(con->nodeid,
-					  page_address(con->rx_page),
-					  con->cb.base, con->cb.len,
-					  PAGE_CACHE_SIZE);
-	if (ret == -EBADMSG) {
-		printk(KERN_INFO "dlm: lowcomms: addr=%p, base=%u, len=%u, "
-		       "iov_len=%u, iov_base[0]=%p, read=%d\n",
-		       page_address(con->rx_page), con->cb.base, con->cb.len,
-		       len, iov[0].iov_base, r);
-	}
-	if (ret < 0)
-		goto out_close;
-	cbuf_eat(&con->cb, ret);
-
-	if (cbuf_empty(&con->cb) && !call_again_soon) {
-		__free_page(con->rx_page);
-		con->rx_page = NULL;
-	}
-
-	if (call_again_soon)
-		goto out_resched;
-	mutex_unlock(&con->sock_mutex);
-	return 0;
-
-out_resched:
-	if (!test_and_set_bit(CF_READ_PENDING, &con->flags))
-		queue_work(recv_workqueue, &con->rwork);
-	mutex_unlock(&con->sock_mutex);
-	return -EAGAIN;
-
-out_close:
-	mutex_unlock(&con->sock_mutex);
-	if (ret != -EAGAIN && !test_bit(CF_IS_OTHERCON, &con->flags)) {
-		close_connection(con, false);
-		/* Reconnect when there is something to send */
-	}
-	/* Don't return success if we really got EOF */
-	if (ret == 0)
-		ret = -EAGAIN;
-
-	return ret;
-}
-
-/* Listening socket is busy, accept a connection */
-static int accept_from_sock(struct connection *con)
-{
-	int result;
-	struct sockaddr_storage peeraddr;
-	struct socket *newsock;
-	int len;
-	int nodeid;
-	struct connection *newcon;
-	struct connection *addcon;
-
-	memset(&peeraddr, 0, sizeof(peeraddr));
-	result = sock_create_kern(dlm_local_addr.ss_family, SOCK_STREAM,
-				  IPPROTO_TCP, &newsock);
-	if (result < 0)
-		return -ENOMEM;
-
-	mutex_lock_nested(&con->sock_mutex, 0);
-
-	result = -ENOTCONN;
-	if (con->sock == NULL)
-		goto accept_err;
-
-	newsock->type = con->sock->type;
-	newsock->ops = con->sock->ops;
-
-	result = con->sock->ops->accept(con->sock, newsock, O_NONBLOCK);
-	if (result < 0)
-		goto accept_err;
-
-	/* Get the connected socket's peer */
-	memset(&peeraddr, 0, sizeof(peeraddr));
-	if (newsock->ops->getname(newsock, (struct sockaddr *)&peeraddr,
-				  &len, 2)) {
-		result = -ECONNABORTED;
-		goto accept_err;
-	}
-
-	/* Get the new node's NODEID */
-	make_sockaddr(&peeraddr, 0, &len);
-	if (dlm_addr_to_nodeid(&peeraddr, &nodeid)) {
-		printk("dlm: connect from non cluster node\n");
-		sock_release(newsock);
-		mutex_unlock(&con->sock_mutex);
-		return -1;
-	}
-
-	log_print("got connection from %d", nodeid);
-
-	/*  Check to see if we already have a connection to this node. This
-	 *  could happen if the two nodes initiate a connection at roughly
-	 *  the same time and the connections cross on the wire.
-	 * TEMPORARY FIX:
-	 *  In this case we store the incoming one in "othercon"
-	 */
-	newcon = nodeid2con(nodeid, GFP_KERNEL);
-	if (!newcon) {
-		result = -ENOMEM;
-		goto accept_err;
-	}
-	mutex_lock_nested(&newcon->sock_mutex, 1);
-	if (newcon->sock) {
-		struct connection *othercon = newcon->othercon;
-
-		if (!othercon) {
-			othercon = kmem_cache_zalloc(con_cache, GFP_KERNEL);
-			if (!othercon) {
-				printk("dlm: failed to allocate incoming socket\n");
-				mutex_unlock(&newcon->sock_mutex);
-				result = -ENOMEM;
-				goto accept_err;
-			}
-			othercon->nodeid = nodeid;
-			othercon->rx_action = receive_from_sock;
-			mutex_init(&othercon->sock_mutex);
-			INIT_WORK(&othercon->swork, process_send_sockets);
-			INIT_WORK(&othercon->rwork, process_recv_sockets);
-			set_bit(CF_IS_OTHERCON, &othercon->flags);
-			newcon->othercon = othercon;
-		}
-		othercon->sock = newsock;
-		newsock->sk->sk_user_data = othercon;
-		add_sock(newsock, othercon);
-		addcon = othercon;
-	}
-	else {
-		newsock->sk->sk_user_data = newcon;
-		newcon->rx_action = receive_from_sock;
-		add_sock(newsock, newcon);
-		addcon = newcon;
-	}
-
-	mutex_unlock(&newcon->sock_mutex);
-
-	/*
-	 * Add it to the active queue in case we got data
-	 * beween processing the accept adding the socket
-	 * to the read_sockets list
-	 */
-	if (!test_and_set_bit(CF_READ_PENDING, &addcon->flags))
-		queue_work(recv_workqueue, &addcon->rwork);
-	mutex_unlock(&con->sock_mutex);
-
-	return 0;
-
-accept_err:
-	mutex_unlock(&con->sock_mutex);
-	sock_release(newsock);
-
-	if (result != -EAGAIN)
-		printk("dlm: error accepting connection from node: %d\n", result);
-	return result;
-}
-
-/* Connect a new socket to its peer */
-static void connect_to_sock(struct connection *con)
-{
-	int result = -EHOSTUNREACH;
-	struct sockaddr_storage saddr;
-	int addr_len;
-	struct socket *sock;
-
-	if (con->nodeid == 0) {
-		log_print("attempt to connect sock 0 foiled");
-		return;
-	}
-
-	mutex_lock(&con->sock_mutex);
-	if (con->retries++ > MAX_CONNECT_RETRIES)
-		goto out;
-
-	/* Some odd races can cause double-connects, ignore them */
-	if (con->sock) {
-		result = 0;
-		goto out;
-	}
-
-	/* Create a socket to communicate with */
-	result = sock_create_kern(dlm_local_addr.ss_family, SOCK_STREAM,
-				  IPPROTO_TCP, &sock);
-	if (result < 0)
-		goto out_err;
-
-	memset(&saddr, 0, sizeof(saddr));
-	if (dlm_nodeid_to_addr(con->nodeid, &saddr))
-		goto out_err;
-
-	sock->sk->sk_user_data = con;
-	con->rx_action = receive_from_sock;
-
-	make_sockaddr(&saddr, dlm_config.ci_tcp_port, &addr_len);
-
-	add_sock(sock, con);
-
-	log_print("connecting to %d", con->nodeid);
-	result =
-		sock->ops->connect(sock, (struct sockaddr *)&saddr, addr_len,
-				   O_NONBLOCK);
-	if (result == -EINPROGRESS)
-		result = 0;
-	if (result == 0)
-		goto out;
-
-out_err:
-	if (con->sock) {
-		sock_release(con->sock);
-		con->sock = NULL;
-	}
-	/*
-	 * Some errors are fatal and this list might need adjusting. For other
-	 * errors we try again until the max number of retries is reached.
-	 */
-	if (result != -EHOSTUNREACH && result != -ENETUNREACH &&
-	    result != -ENETDOWN && result != EINVAL
-	    && result != -EPROTONOSUPPORT) {
-		lowcomms_connect_sock(con);
-		result = 0;
-	}
-out:
-	mutex_unlock(&con->sock_mutex);
-	return;
-}
-
-static struct socket *create_listen_sock(struct connection *con,
-					 struct sockaddr_storage *saddr)
-{
-	struct socket *sock = NULL;
-	mm_segment_t fs;
-	int result = 0;
-	int one = 1;
-	int addr_len;
-
-	if (dlm_local_addr.ss_family == AF_INET)
-		addr_len = sizeof(struct sockaddr_in);
-	else
-		addr_len = sizeof(struct sockaddr_in6);
-
-	/* Create a socket to communicate with */
-	result = sock_create_kern(dlm_local_addr.ss_family, SOCK_STREAM, IPPROTO_TCP, &sock);
-	if (result < 0) {
-		printk("dlm: Can't create listening comms socket\n");
-		goto create_out;
-	}
-
-	fs = get_fs();
-	set_fs(get_ds());
-	result = sock_setsockopt(sock, SOL_SOCKET, SO_REUSEADDR,
-				 (char *)&one, sizeof(one));
-	set_fs(fs);
-	if (result < 0) {
-		printk("dlm: Failed to set SO_REUSEADDR on socket: result=%d\n",
-		       result);
-	}
-	sock->sk->sk_user_data = con;
-	con->rx_action = accept_from_sock;
-	con->sock = sock;
-
-	/* Bind to our port */
-	make_sockaddr(saddr, dlm_config.ci_tcp_port, &addr_len);
-	result = sock->ops->bind(sock, (struct sockaddr *) saddr, addr_len);
-	if (result < 0) {
-		printk("dlm: Can't bind to port %d\n", dlm_config.ci_tcp_port);
-		sock_release(sock);
-		sock = NULL;
-		con->sock = NULL;
-		goto create_out;
-	}
-
-	fs = get_fs();
-	set_fs(get_ds());
-
-	result = sock_setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE,
-				 (char *)&one, sizeof(one));
-	set_fs(fs);
-	if (result < 0) {
-		printk("dlm: Set keepalive failed: %d\n", result);
-	}
-
-	result = sock->ops->listen(sock, 5);
-	if (result < 0) {
-		printk("dlm: Can't listen on port %d\n", dlm_config.ci_tcp_port);
-		sock_release(sock);
-		sock = NULL;
-		goto create_out;
-	}
-
-create_out:
-	return sock;
-}
-
-
-/* Listen on all interfaces */
-static int listen_for_all(void)
-{
-	struct socket *sock = NULL;
-	struct connection *con = nodeid2con(0, GFP_KERNEL);
-	int result = -EINVAL;
-
-	/* We don't support multi-homed hosts */
-	set_bit(CF_IS_OTHERCON, &con->flags);
-
-	sock = create_listen_sock(con, &dlm_local_addr);
-	if (sock) {
-		add_sock(sock, con);
-		result = 0;
-	}
-	else {
-		result = -EADDRINUSE;
-	}
-
-	return result;
-}
-
-
-
-static struct writequeue_entry *new_writequeue_entry(struct connection *con,
-						     gfp_t allocation)
-{
-	struct writequeue_entry *entry;
-
-	entry = kmalloc(sizeof(struct writequeue_entry), allocation);
-	if (!entry)
-		return NULL;
-
-	entry->page = alloc_page(allocation);
-	if (!entry->page) {
-		kfree(entry);
-		return NULL;
-	}
-
-	entry->offset = 0;
-	entry->len = 0;
-	entry->end = 0;
-	entry->users = 0;
-	entry->con = con;
-
-	return entry;
-}
-
-void *dlm_lowcomms_get_buffer(int nodeid, int len,
-			      gfp_t allocation, char **ppc)
-{
-	struct connection *con;
-	struct writequeue_entry *e;
-	int offset = 0;
-	int users = 0;
-
-	con = nodeid2con(nodeid, allocation);
-	if (!con)
-		return NULL;
-
-	spin_lock(&con->writequeue_lock);
-	e = list_entry(con->writequeue.prev, struct writequeue_entry, list);
-	if ((&e->list == &con->writequeue) ||
-	    (PAGE_CACHE_SIZE - e->end < len)) {
-		e = NULL;
-	} else {
-		offset = e->end;
-		e->end += len;
-		users = e->users++;
-	}
-	spin_unlock(&con->writequeue_lock);
-
-	if (e) {
-	got_one:
-		if (users == 0)
-			kmap(e->page);
-		*ppc = page_address(e->page) + offset;
-		return e;
-	}
-
-	e = new_writequeue_entry(con, allocation);
-	if (e) {
-		spin_lock(&con->writequeue_lock);
-		offset = e->end;
-		e->end += len;
-		users = e->users++;
-		list_add_tail(&e->list, &con->writequeue);
-		spin_unlock(&con->writequeue_lock);
-		goto got_one;
-	}
-	return NULL;
-}
-
-void dlm_lowcomms_commit_buffer(void *mh)
-{
-	struct writequeue_entry *e = (struct writequeue_entry *)mh;
-	struct connection *con = e->con;
-	int users;
-
-	spin_lock(&con->writequeue_lock);
-	users = --e->users;
-	if (users)
-		goto out;
-	e->len = e->end - e->offset;
-	kunmap(e->page);
-	spin_unlock(&con->writequeue_lock);
-
-	if (!test_and_set_bit(CF_WRITE_PENDING, &con->flags)) {
-		queue_work(send_workqueue, &con->swork);
-	}
-	return;
-
-out:
-	spin_unlock(&con->writequeue_lock);
-	return;
-}
-
-static void free_entry(struct writequeue_entry *e)
-{
-	__free_page(e->page);
-	kfree(e);
-}
-
-/* Send a message */
-static void send_to_sock(struct connection *con)
-{
-	int ret = 0;
-	ssize_t(*sendpage) (struct socket *, struct page *, int, size_t, int);
-	const int msg_flags = MSG_DONTWAIT | MSG_NOSIGNAL;
-	struct writequeue_entry *e;
-	int len, offset;
-
-	mutex_lock(&con->sock_mutex);
-	if (con->sock == NULL)
-		goto out_connect;
-
-	sendpage = con->sock->ops->sendpage;
-
-	spin_lock(&con->writequeue_lock);
-	for (;;) {
-		e = list_entry(con->writequeue.next, struct writequeue_entry,
-			       list);
-		if ((struct list_head *) e == &con->writequeue)
-			break;
-
-		len = e->len;
-		offset = e->offset;
-		BUG_ON(len == 0 && e->users == 0);
-		spin_unlock(&con->writequeue_lock);
-		kmap(e->page);
-
-		ret = 0;
-		if (len) {
-			ret = sendpage(con->sock, e->page, offset, len,
-				       msg_flags);
-			if (ret == -EAGAIN || ret == 0)
-				goto out;
-			if (ret <= 0)
-				goto send_error;
-		}
-		else {
-			/* Don't starve people filling buffers */
-			cond_resched();
-		}
-
-		spin_lock(&con->writequeue_lock);
-		e->offset += ret;
-		e->len -= ret;
-
-		if (e->len == 0 && e->users == 0) {
-			list_del(&e->list);
-			kunmap(e->page);
-			free_entry(e);
-			continue;
-		}
-	}
-	spin_unlock(&con->writequeue_lock);
-out:
-	mutex_unlock(&con->sock_mutex);
-	return;
-
-send_error:
-	mutex_unlock(&con->sock_mutex);
-	close_connection(con, false);
-	lowcomms_connect_sock(con);
-	return;
-
-out_connect:
-	mutex_unlock(&con->sock_mutex);
-	connect_to_sock(con);
-	return;
-}
-
-static void clean_one_writequeue(struct connection *con)
-{
-	struct list_head *list;
-	struct list_head *temp;
-
-	spin_lock(&con->writequeue_lock);
-	list_for_each_safe(list, temp, &con->writequeue) {
-		struct writequeue_entry *e =
-			list_entry(list, struct writequeue_entry, list);
-		list_del(&e->list);
-		free_entry(e);
-	}
-	spin_unlock(&con->writequeue_lock);
-}
-
-/* Called from recovery when it knows that a node has
-   left the cluster */
-int dlm_lowcomms_close(int nodeid)
-{
-	struct connection *con;
-
-	if (!connections)
-		goto out;
-
-	log_print("closing connection to node %d", nodeid);
-	con = nodeid2con(nodeid, 0);
-	if (con) {
-		clean_one_writequeue(con);
-		close_connection(con, true);
-	}
-	return 0;
-
-out:
-	return -1;
-}
-
-/* Look for activity on active sockets */
-static void process_recv_sockets(struct work_struct *work)
-{
-	struct connection *con = container_of(work, struct connection, rwork);
-	int err;
-
-	clear_bit(CF_READ_PENDING, &con->flags);
-	do {
-		err = con->rx_action(con);
-	} while (!err);
-}
-
-
-static void process_send_sockets(struct work_struct *work)
-{
-	struct connection *con = container_of(work, struct connection, swork);
-
-	if (test_and_clear_bit(CF_CONNECT_PENDING, &con->flags)) {
-		connect_to_sock(con);
-	}
-
-	clear_bit(CF_WRITE_PENDING, &con->flags);
-	send_to_sock(con);
-}
-
-
-/* Discard all entries on the write queues */
-static void clean_writequeues(void)
-{
-	int nodeid;
-
-	for (nodeid = 1; nodeid < conn_array_size; nodeid++) {
-		struct connection *con = nodeid2con(nodeid, 0);
-
-		if (con)
-			clean_one_writequeue(con);
-	}
-}
-
-static void work_stop(void)
-{
-	destroy_workqueue(recv_workqueue);
-	destroy_workqueue(send_workqueue);
-}
-
-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;
-	}
-
-	send_workqueue = create_singlethread_workqueue("dlm_send");
-	error = IS_ERR(send_workqueue);
-	if (error) {
-		log_print("can't start dlm_send %d", error);
-		destroy_workqueue(recv_workqueue);
-		return error;
-	}
-
-	return 0;
-}
-
-void dlm_lowcomms_stop(void)
-{
-	int i;
-
-	/* Set all the flags to prevent any
-	   socket activity.
-	*/
-	for (i = 0; i < conn_array_size; i++) {
-		if (connections[i])
-			connections[i]->flags |= 0xFF;
-	}
-
-	work_stop();
-	clean_writequeues();
-
-	for (i = 0; i < conn_array_size; i++) {
-		if (connections[i]) {
-			close_connection(connections[i], true);
-			if (connections[i]->othercon)
-				kmem_cache_free(con_cache, connections[i]->othercon);
-			kmem_cache_free(con_cache, connections[i]);
-		}
-	}
-
-	kfree(connections);
-	connections = NULL;
-
-	kmem_cache_destroy(con_cache);
-}
-
-/* This is quite likely to sleep... */
-int dlm_lowcomms_start(void)
-{
-	int error = 0;
-
-	error = -ENOMEM;
-	connections = kzalloc(sizeof(struct connection *) *
-			      NODE_INCREMENT, GFP_KERNEL);
-	if (!connections)
-		goto out;
-
-	conn_array_size = NODE_INCREMENT;
-
-	if (dlm_our_addr(&dlm_local_addr, 0)) {
-		log_print("no local IP address has been set");
-		goto fail_free_conn;
-	}
-	if (!dlm_our_addr(&dlm_local_addr, 1)) {
-		log_print("This dlm comms module does not support multi-homed clustering");
-		goto fail_free_conn;
-	}
-
-	con_cache = kmem_cache_create("dlm_conn", sizeof(struct connection),
-				      __alignof__(struct connection), 0,
-				      NULL, NULL);
-	if (!con_cache)
-		goto fail_free_conn;
-
-
-	/* Start listening */
-	error = listen_for_all();
-	if (error)
-		goto fail_unlisten;
-
-	error = work_start();
-	if (error)
-		goto fail_unlisten;
-
-	return 0;
-
-fail_unlisten:
-	close_connection(connections[0], false);
-	kmem_cache_free(con_cache, connections[0]);
-	kmem_cache_destroy(con_cache);
-
-fail_free_conn:
-	kfree(connections);
-
-out:
-	return error;
-}
-
-/*
- * Overrides for Emacs so that we follow Linus's tabbing style.
- * Emacs will notice this stuff at the end of the file and automatically
- * adjust the settings for this buffer only.  This must remain at the end
- * of the file.
- * ---------------------------------------------------------------------------
- * Local variables:
- * c-file-style: "linux"
- * End:
- */