Date: Thu, 02 Nov 2006 17:14:49 +0000
From: Patrick Caulfield <pcaulfie@redhat.com>
Subject: [RHEL5U2 BZ#211777 & others] dlm: add tcp communications

OK, I expect flak for this, I'm sorry.

The SCTP stack in the current kernel doesn't seem to be reliable enough to support the DLM at the moment so this is a forward-port
of the communications part of the RHEL4 DLM. I've renamed the sctp one to lowcomms-sctp.c (hence the size of the patch) and left it
in for the following reasons:

1. The TCP one doesn't support multi-homing
2. I hope SCTP will mature to the point where we can use it again and provide
   multi-home support.
3. Having TCP as an option allows users to do flow control on the traffic if needs be.

There's a Kconfig option to select which one you want, TCP is the default.

/me hides
-- 

patrick


Index: latest/fs/dlm/Kconfig
===================================================================
--- latest.orig/fs/dlm/Kconfig
+++ latest/fs/dlm/Kconfig
@@ -10,6 +10,23 @@ config DLM
 	A general purpose distributed lock manager for kernel or userspace
 	applications.
 
+choice
+	prompt "Select DLM communications protocol"
+	depends on DLM
+	default DLM_TCP
+	help
+	The DLM Can use TCP or SCTP for it's network communications.
+	SCTP supports multi-homed operations whereas TCP doesn't.
+	However, SCTP seems to have stability problems at the moment.
+
+config DLM_TCP
+	bool "TCP/IP"
+
+config DLM_SCTP
+	bool "SCTP"
+
+endchoice
+
 config DLM_DEBUG
 	bool "DLM debugging"
 	depends on DLM
Index: latest/fs/dlm/Makefile
===================================================================
--- latest.orig/fs/dlm/Makefile
+++ latest/fs/dlm/Makefile
@@ -4,7 +4,6 @@ dlm-y :=			ast.o \
 				dir.o \
 				lock.o \
 				lockspace.o \
-				lowcomms.o \
 				main.o \
 				member.o \
 				memory.o \
@@ -17,3 +16,6 @@ dlm-y :=			ast.o \
 				util.o
 dlm-$(CONFIG_DLM_DEBUG) +=	debug_fs.o
 
+dlm-$(CONFIG_DLM_TCP)   += lowcomms-tcp.o
+
+dlm-$(CONFIG_DLM_SCTP)  += lowcomms-sctp.o
\ No newline at end of file
Index: latest/fs/dlm/lowcomms-sctp.c
===================================================================
--- /dev/null
+++ latest/fs/dlm/lowcomms-sctp.c
@@ -0,0 +1,1238 @@
+/******************************************************************************
+*******************************************************************************
+**
+**  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
+**  Copyright (C) 2004-2005 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 (well, hardly ever) waits.
+ *
+ */
+
+#include <asm/ioctls.h>
+#include <net/sock.h>
+#include <net/tcp.h>
+#include <net/sctp/user.h>
+#include <linux/pagemap.h>
+#include <linux/socket.h>
+#include <linux/idr.h>
+
+#include "dlm_internal.h"
+#include "lowcomms.h"
+#include "config.h"
+#include "midcomms.h"
+
+static struct sockaddr_storage *dlm_local_addr[DLM_MAX_ADDR_COUNT];
+static int			dlm_local_count;
+static int			dlm_local_nodeid;
+
+/* One of these per connected node */
+
+#define NI_INIT_PENDING 1
+#define NI_WRITE_PENDING 2
+
+struct nodeinfo {
+	spinlock_t		lock;
+	sctp_assoc_t		assoc_id;
+	unsigned long		flags;
+	struct list_head	write_list; /* nodes with pending writes */
+	struct list_head	writequeue; /* outgoing writequeue_entries */
+	spinlock_t		writequeue_lock;
+	int			nodeid;
+};
+
+static DEFINE_IDR(nodeinfo_idr);
+static struct rw_semaphore	nodeinfo_lock;
+static int			max_nodeid;
+
+struct cbuf {
+	unsigned		base;
+	unsigned		len;
+	unsigned		mask;
+};
+
+/* Just the one of these, now. But this struct keeps
+   the connection-specific variables together */
+
+#define CF_READ_PENDING 1
+
+struct connection {
+	struct socket          *sock;
+	unsigned long		flags;
+	struct page            *rx_page;
+	atomic_t		waiting_requests;
+	struct cbuf		cb;
+	int                     eagain_flag;
+};
+
+/* 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 nodeinfo        *ni;
+};
+
+#define CBUF_ADD(cb, n) do { (cb)->len += n; } while(0)
+#define CBUF_EMPTY(cb) ((cb)->len == 0)
+#define CBUF_MAY_ADD(cb, n) (((cb)->len + (n)) < ((cb)->mask + 1))
+#define CBUF_DATA(cb) (((cb)->base + (cb)->len) & (cb)->mask)
+
+#define CBUF_INIT(cb, size) \
+do { \
+	(cb)->base = (cb)->len = 0; \
+	(cb)->mask = ((size)-1); \
+} while(0)
+
+#define CBUF_EAT(cb, n) \
+do { \
+	(cb)->len  -= (n); \
+	(cb)->base += (n); \
+	(cb)->base &= (cb)->mask; \
+} while(0)
+
+
+/* List of nodes which have writes pending */
+static struct list_head write_nodes;
+static spinlock_t write_nodes_lock;
+
+/* Maximum number of incoming messages to process before
+ * doing a schedule()
+ */
+#define MAX_RX_MSG_COUNT 25
+
+/* Manage daemons */
+static struct task_struct *recv_task;
+static struct task_struct *send_task;
+static wait_queue_head_t lowcomms_recv_wait;
+static atomic_t accepting;
+
+/* The SCTP connection */
+static struct connection sctp_con;
+
+
+static int nodeid_to_addr(int nodeid, struct sockaddr *retaddr)
+{
+	struct sockaddr_storage addr;
+	int error;
+
+	if (!dlm_local_count)
+		return -1;
+
+	error = dlm_nodeid_to_addr(nodeid, &addr);
+	if (error)
+		return error;
+
+	if (dlm_local_addr[0]->ss_family == AF_INET) {
+	        struct sockaddr_in *in4  = (struct sockaddr_in *) &addr;
+		struct sockaddr_in *ret4 = (struct sockaddr_in *) retaddr;
+		ret4->sin_addr.s_addr = in4->sin_addr.s_addr;
+	} else {
+	        struct sockaddr_in6 *in6  = (struct sockaddr_in6 *) &addr;
+		struct sockaddr_in6 *ret6 = (struct sockaddr_in6 *) retaddr;
+		memcpy(&ret6->sin6_addr, &in6->sin6_addr,
+		       sizeof(in6->sin6_addr));
+	}
+
+	return 0;
+}
+
+static struct nodeinfo *nodeid2nodeinfo(int nodeid, int alloc)
+{
+	struct nodeinfo *ni;
+	int r;
+	int n;
+
+	down_read(&nodeinfo_lock);
+	ni = idr_find(&nodeinfo_idr, nodeid);
+	up_read(&nodeinfo_lock);
+
+	if (!ni && alloc) {
+		down_write(&nodeinfo_lock);
+
+		ni = idr_find(&nodeinfo_idr, nodeid);
+		if (ni)
+			goto out_up;
+
+		r = idr_pre_get(&nodeinfo_idr, alloc);
+		if (!r)
+			goto out_up;
+
+		ni = kmalloc(sizeof(struct nodeinfo), alloc);
+		if (!ni)
+			goto out_up;
+
+		r = idr_get_new_above(&nodeinfo_idr, ni, nodeid, &n);
+		if (r) {
+			kfree(ni);
+			ni = NULL;
+			goto out_up;
+		}
+		if (n != nodeid) {
+			idr_remove(&nodeinfo_idr, n);
+			kfree(ni);
+			ni = NULL;
+			goto out_up;
+		}
+		memset(ni, 0, sizeof(struct nodeinfo));
+		spin_lock_init(&ni->lock);
+		INIT_LIST_HEAD(&ni->writequeue);
+		spin_lock_init(&ni->writequeue_lock);
+		ni->nodeid = nodeid;
+
+		if (nodeid > max_nodeid)
+			max_nodeid = nodeid;
+	out_up:
+		up_write(&nodeinfo_lock);
+	}
+
+	return ni;
+}
+
+/* Don't call this too often... */
+static struct nodeinfo *assoc2nodeinfo(sctp_assoc_t assoc)
+{
+	int i;
+	struct nodeinfo *ni;
+
+	for (i=1; i<=max_nodeid; i++) {
+		ni = nodeid2nodeinfo(i, 0);
+		if (ni && ni->assoc_id == assoc)
+			return ni;
+	}
+	return NULL;
+}
+
+/* Data or notification available on socket */
+static void lowcomms_data_ready(struct sock *sk, int count_unused)
+{
+	atomic_inc(&sctp_con.waiting_requests);
+	if (test_and_set_bit(CF_READ_PENDING, &sctp_con.flags))
+		return;
+
+	wake_up_interruptible(&lowcomms_recv_wait);
+}
+
+
+/* Add the port number to an IP6 or 4 sockaddr and return the address length.
+   Also padd out the struct with zeros to make comparisons meaningful */
+
+static void make_sockaddr(struct sockaddr_storage *saddr, uint16_t port,
+			  int *addr_len)
+{
+	struct sockaddr_in *local4_addr;
+	struct sockaddr_in6 *local6_addr;
+
+	if (!dlm_local_count)
+		return;
+
+	if (!port) {
+		if (dlm_local_addr[0]->ss_family == AF_INET) {
+			local4_addr = (struct sockaddr_in *)dlm_local_addr[0];
+			port = be16_to_cpu(local4_addr->sin_port);
+		} else {
+			local6_addr = (struct sockaddr_in6 *)dlm_local_addr[0];
+			port = be16_to_cpu(local6_addr->sin6_port);
+		}
+	}
+
+	saddr->ss_family = dlm_local_addr[0]->ss_family;
+	if (dlm_local_addr[0]->ss_family == AF_INET) {
+		struct sockaddr_in *in4_addr = (struct sockaddr_in *)saddr;
+		in4_addr->sin_port = cpu_to_be16(port);
+		memset(&in4_addr->sin_zero, 0, sizeof(in4_addr->sin_zero));
+		memset(in4_addr+1, 0, sizeof(struct sockaddr_storage) -
+				      sizeof(struct sockaddr_in));
+		*addr_len = sizeof(struct sockaddr_in);
+	} else {
+		struct sockaddr_in6 *in6_addr = (struct sockaddr_in6 *)saddr;
+		in6_addr->sin6_port = cpu_to_be16(port);
+		memset(in6_addr+1, 0, sizeof(struct sockaddr_storage) -
+				      sizeof(struct sockaddr_in6));
+		*addr_len = sizeof(struct sockaddr_in6);
+	}
+}
+
+/* Close the connection and tidy up */
+static void close_connection(void)
+{
+	if (sctp_con.sock) {
+		sock_release(sctp_con.sock);
+		sctp_con.sock = NULL;
+	}
+
+	if (sctp_con.rx_page) {
+		__free_page(sctp_con.rx_page);
+		sctp_con.rx_page = NULL;
+	}
+}
+
+/* We only send shutdown messages to nodes that are not part of the cluster */
+static void send_shutdown(sctp_assoc_t associd)
+{
+	static char outcmsg[CMSG_SPACE(sizeof(struct sctp_sndrcvinfo))];
+	struct msghdr outmessage;
+	struct cmsghdr *cmsg;
+	struct sctp_sndrcvinfo *sinfo;
+	int ret;
+
+	outmessage.msg_name = NULL;
+	outmessage.msg_namelen = 0;
+	outmessage.msg_control = outcmsg;
+	outmessage.msg_controllen = sizeof(outcmsg);
+	outmessage.msg_flags = MSG_EOR;
+
+	cmsg = CMSG_FIRSTHDR(&outmessage);
+	cmsg->cmsg_level = IPPROTO_SCTP;
+	cmsg->cmsg_type = SCTP_SNDRCV;
+	cmsg->cmsg_len = CMSG_LEN(sizeof(struct sctp_sndrcvinfo));
+	outmessage.msg_controllen = cmsg->cmsg_len;
+	sinfo = (struct sctp_sndrcvinfo *)CMSG_DATA(cmsg);
+	memset(sinfo, 0x00, sizeof(struct sctp_sndrcvinfo));
+
+	sinfo->sinfo_flags |= MSG_EOF;
+	sinfo->sinfo_assoc_id = associd;
+
+	ret = kernel_sendmsg(sctp_con.sock, &outmessage, NULL, 0, 0);
+
+	if (ret != 0)
+		log_print("send EOF to node failed: %d", ret);
+}
+
+
+/* INIT failed but we don't know which node...
+   restart INIT on all pending nodes */
+static void init_failed(void)
+{
+	int i;
+	struct nodeinfo *ni;
+
+	for (i=1; i<=max_nodeid; i++) {
+		ni = nodeid2nodeinfo(i, 0);
+		if (!ni)
+			continue;
+
+		if (test_and_clear_bit(NI_INIT_PENDING, &ni->flags)) {
+			ni->assoc_id = 0;
+			if (!test_and_set_bit(NI_WRITE_PENDING, &ni->flags)) {
+				spin_lock_bh(&write_nodes_lock);
+				list_add_tail(&ni->write_list, &write_nodes);
+				spin_unlock_bh(&write_nodes_lock);
+			}
+		}
+	}
+	wake_up_process(send_task);
+}
+
+/* Something happened to an association */
+static void process_sctp_notification(struct msghdr *msg, char *buf)
+{
+	union sctp_notification *sn = (union sctp_notification *)buf;
+
+	if (sn->sn_header.sn_type == SCTP_ASSOC_CHANGE) {
+		switch (sn->sn_assoc_change.sac_state) {
+
+		case SCTP_COMM_UP:
+		case SCTP_RESTART:
+		{
+			/* Check that the new node is in the lockspace */
+			struct sctp_prim prim;
+			mm_segment_t fs;
+			int nodeid;
+			int prim_len, ret;
+			int addr_len;
+			struct nodeinfo *ni;
+
+			/* This seems to happen when we received a connection
+			 * too early... or something...  anyway, it happens but
+			 * we always seem to get a real message too, see
+			 * receive_from_sock */
+
+			if ((int)sn->sn_assoc_change.sac_assoc_id <= 0) {
+				log_print("COMM_UP for invalid assoc ID %d",
+					 (int)sn->sn_assoc_change.sac_assoc_id);
+				init_failed();
+				return;
+			}
+			memset(&prim, 0, sizeof(struct sctp_prim));
+			prim_len = sizeof(struct sctp_prim);
+			prim.ssp_assoc_id = sn->sn_assoc_change.sac_assoc_id;
+
+			fs = get_fs();
+			set_fs(get_ds());
+			ret = sctp_con.sock->ops->getsockopt(sctp_con.sock,
+						IPPROTO_SCTP, SCTP_PRIMARY_ADDR,
+						(char*)&prim, &prim_len);
+			set_fs(fs);
+			if (ret < 0) {
+				struct nodeinfo *ni;
+
+				log_print("getsockopt/sctp_primary_addr on "
+					  "new assoc %d failed : %d",
+				    (int)sn->sn_assoc_change.sac_assoc_id, ret);
+
+				/* Retry INIT later */
+				ni = assoc2nodeinfo(sn->sn_assoc_change.sac_assoc_id);
+				if (ni)
+					clear_bit(NI_INIT_PENDING, &ni->flags);
+				return;
+			}
+			make_sockaddr(&prim.ssp_addr, 0, &addr_len);
+			if (dlm_addr_to_nodeid(&prim.ssp_addr, &nodeid)) {
+				log_print("reject connect from unknown addr");
+				send_shutdown(prim.ssp_assoc_id);
+				return;
+			}
+
+			ni = nodeid2nodeinfo(nodeid, GFP_KERNEL);
+			if (!ni)
+				return;
+
+			/* Save the assoc ID */
+			spin_lock(&ni->lock);
+			ni->assoc_id = sn->sn_assoc_change.sac_assoc_id;
+			spin_unlock(&ni->lock);
+
+			log_print("got new/restarted association %d nodeid %d",
+			       (int)sn->sn_assoc_change.sac_assoc_id, nodeid);
+
+			/* Send any pending writes */
+			clear_bit(NI_INIT_PENDING, &ni->flags);
+			if (!test_and_set_bit(NI_WRITE_PENDING, &ni->flags)) {
+				spin_lock_bh(&write_nodes_lock);
+				list_add_tail(&ni->write_list, &write_nodes);
+				spin_unlock_bh(&write_nodes_lock);
+			}
+			wake_up_process(send_task);
+		}
+		break;
+
+		case SCTP_COMM_LOST:
+		case SCTP_SHUTDOWN_COMP:
+		{
+			struct nodeinfo *ni;
+
+			ni = assoc2nodeinfo(sn->sn_assoc_change.sac_assoc_id);
+			if (ni) {
+				spin_lock(&ni->lock);
+				ni->assoc_id = 0;
+				spin_unlock(&ni->lock);
+			}
+		}
+		break;
+
+		/* We don't know which INIT failed, so clear the PENDING flags
+		 * on them all.  if assoc_id is zero then it will then try
+		 * again */
+
+		case SCTP_CANT_STR_ASSOC:
+		{
+			log_print("Can't start SCTP association - retrying");
+			init_failed();
+		}
+		break;
+
+		default:
+			log_print("unexpected SCTP assoc change id=%d state=%d",
+				  (int)sn->sn_assoc_change.sac_assoc_id,
+				  sn->sn_assoc_change.sac_state);
+		}
+	}
+}
+
+/* Data received from remote end */
+static int receive_from_sock(void)
+{
+	int ret = 0;
+	struct msghdr msg;
+	struct kvec iov[2];
+	unsigned len;
+	int r;
+	struct sctp_sndrcvinfo *sinfo;
+	struct cmsghdr *cmsg;
+	struct nodeinfo *ni;
+
+	/* These two are marginally too big for stack allocation, but this
+	 * function is (currently) only called by dlm_recvd so static should be
+	 * OK.
+	 */
+	static struct sockaddr_storage msgname;
+	static char incmsg[CMSG_SPACE(sizeof(struct sctp_sndrcvinfo))];
+
+	if (sctp_con.sock == NULL)
+		goto out;
+
+	if (sctp_con.rx_page == NULL) {
+		/*
+		 * This doesn't need to be atomic, but I think it should
+		 * improve performance if it is.
+		 */
+		sctp_con.rx_page = alloc_page(GFP_ATOMIC);
+		if (sctp_con.rx_page == NULL)
+			goto out_resched;
+		CBUF_INIT(&sctp_con.cb, PAGE_CACHE_SIZE);
+	}
+
+	memset(&incmsg, 0, sizeof(incmsg));
+	memset(&msgname, 0, sizeof(msgname));
+
+	memset(incmsg, 0, sizeof(incmsg));
+	msg.msg_name = &msgname;
+	msg.msg_namelen = sizeof(msgname);
+	msg.msg_flags = 0;
+	msg.msg_control = incmsg;
+	msg.msg_controllen = sizeof(incmsg);
+
+	/* I don't see why this circular buffer stuff is necessary for SCTP
+	 * which is a packet-based protocol, but the whole thing breaks under
+	 * load without it! The overhead is minimal (and is in the TCP lowcomms
+	 * anyway, of course) so I'll leave it in until I can figure out what's
+	 * really happening.
+	 */
+
+	/*
+	 * 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 = sctp_con.cb.base - CBUF_DATA(&sctp_con.cb);
+	iov[0].iov_base = page_address(sctp_con.rx_page) +
+			  CBUF_DATA(&sctp_con.cb);
+	iov[1].iov_len = 0;
+
+	/*
+	 * 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(&sctp_con.cb) >= sctp_con.cb.base) {
+		iov[0].iov_len = PAGE_CACHE_SIZE - CBUF_DATA(&sctp_con.cb);
+		iov[1].iov_len = sctp_con.cb.base;
+		iov[1].iov_base = page_address(sctp_con.rx_page);
+		msg.msg_iovlen = 2;
+	}
+	len = iov[0].iov_len + iov[1].iov_len;
+
+	r = ret = kernel_recvmsg(sctp_con.sock, &msg, iov, 1, len,
+				 MSG_NOSIGNAL | MSG_DONTWAIT);
+	if (ret <= 0)
+		goto out_close;
+
+	msg.msg_control = incmsg;
+	msg.msg_controllen = sizeof(incmsg);
+	cmsg = CMSG_FIRSTHDR(&msg);
+	sinfo = (struct sctp_sndrcvinfo *)CMSG_DATA(cmsg);
+
+	if (msg.msg_flags & MSG_NOTIFICATION) {
+		process_sctp_notification(&msg, page_address(sctp_con.rx_page));
+		return 0;
+	}
+
+	/* Is this a new association ? */
+	ni = nodeid2nodeinfo(le32_to_cpu(sinfo->sinfo_ppid), GFP_KERNEL);
+	if (ni) {
+		ni->assoc_id = sinfo->sinfo_assoc_id;
+		if (test_and_clear_bit(NI_INIT_PENDING, &ni->flags)) {
+
+			if (!test_and_set_bit(NI_WRITE_PENDING, &ni->flags)) {
+				spin_lock_bh(&write_nodes_lock);
+				list_add_tail(&ni->write_list, &write_nodes);
+				spin_unlock_bh(&write_nodes_lock);
+			}
+			wake_up_process(send_task);
+		}
+	}
+
+	/* INIT sends a message with length of 1 - ignore it */
+	if (r == 1)
+		return 0;
+
+	CBUF_ADD(&sctp_con.cb, ret);
+	ret = dlm_process_incoming_buffer(cpu_to_le32(sinfo->sinfo_ppid),
+					  page_address(sctp_con.rx_page),
+					  sctp_con.cb.base, sctp_con.cb.len,
+					  PAGE_CACHE_SIZE);
+	if (ret < 0)
+		goto out_close;
+	CBUF_EAT(&sctp_con.cb, ret);
+
+      out:
+	ret = 0;
+	goto out_ret;
+
+      out_resched:
+	lowcomms_data_ready(sctp_con.sock->sk, 0);
+	ret = 0;
+	schedule();
+	goto out_ret;
+
+      out_close:
+	if (ret != -EAGAIN)
+		log_print("error reading from sctp socket: %d", ret);
+      out_ret:
+	return ret;
+}
+
+/* Bind to an IP address. SCTP allows multiple address so it can do multi-homing */
+static int add_bind_addr(struct sockaddr_storage *addr, int addr_len, int num)
+{
+	mm_segment_t fs;
+	int result = 0;
+
+	fs = get_fs();
+	set_fs(get_ds());
+	if (num == 1)
+		result = sctp_con.sock->ops->bind(sctp_con.sock,
+					(struct sockaddr *) addr, addr_len);
+	else
+		result = sctp_con.sock->ops->setsockopt(sctp_con.sock, SOL_SCTP,
+				SCTP_SOCKOPT_BINDX_ADD, (char *)addr, addr_len);
+	set_fs(fs);
+
+	if (result < 0)
+		log_print("Can't bind to port %d addr number %d",
+			  dlm_config.tcp_port, num);
+
+	return result;
+}
+
+static void init_local(void)
+{
+	struct sockaddr_storage sas, *addr;
+	int i;
+
+	dlm_local_nodeid = dlm_our_nodeid();
+
+	for (i = 0; i < DLM_MAX_ADDR_COUNT - 1; i++) {
+		if (dlm_our_addr(&sas, i))
+			break;
+
+		addr = kmalloc(sizeof(*addr), GFP_KERNEL);
+		if (!addr)
+			break;
+		memcpy(addr, &sas, sizeof(*addr));
+		dlm_local_addr[dlm_local_count++] = addr;
+	}
+}
+
+/* Initialise SCTP socket and bind to all interfaces */
+static int init_sock(void)
+{
+	mm_segment_t fs;
+	struct socket *sock = NULL;
+	struct sockaddr_storage localaddr;
+	struct sctp_event_subscribe subscribe;
+	int result = -EINVAL, num = 1, i, addr_len;
+
+	if (!dlm_local_count) {
+		init_local();
+		if (!dlm_local_count) {
+			log_print("no local IP address has been set");
+			goto out;
+		}
+	}
+
+	result = sock_create_kern(dlm_local_addr[0]->ss_family, SOCK_SEQPACKET,
+				  IPPROTO_SCTP, &sock);
+	if (result < 0) {
+		log_print("Can't create comms socket, check SCTP is loaded");
+		goto out;
+	}
+
+	/* Listen for events */
+	memset(&subscribe, 0, sizeof(subscribe));
+	subscribe.sctp_data_io_event = 1;
+	subscribe.sctp_association_event = 1;
+	subscribe.sctp_send_failure_event = 1;
+	subscribe.sctp_shutdown_event = 1;
+	subscribe.sctp_partial_delivery_event = 1;
+
+	fs = get_fs();
+	set_fs(get_ds());
+	result = sock->ops->setsockopt(sock, SOL_SCTP, SCTP_EVENTS,
+				       (char *)&subscribe, sizeof(subscribe));
+	set_fs(fs);
+
+	if (result < 0) {
+		log_print("Failed to set SCTP_EVENTS on socket: result=%d",
+			  result);
+		goto create_delsock;
+	}
+
+	/* Init con struct */
+	sock->sk->sk_user_data = &sctp_con;
+	sctp_con.sock = sock;
+	sctp_con.sock->sk->sk_data_ready = lowcomms_data_ready;
+
+	/* Bind to all interfaces. */
+	for (i = 0; i < dlm_local_count; i++) {
+		memcpy(&localaddr, dlm_local_addr[i], sizeof(localaddr));
+		make_sockaddr(&localaddr, dlm_config.tcp_port, &addr_len);
+
+		result = add_bind_addr(&localaddr, addr_len, num);
+		if (result)
+			goto create_delsock;
+		++num;
+	}
+
+	result = sock->ops->listen(sock, 5);
+	if (result < 0) {
+		log_print("Can't set socket listening");
+		goto create_delsock;
+	}
+
+	return 0;
+
+ create_delsock:
+	sock_release(sock);
+	sctp_con.sock = NULL;
+ out:
+	return result;
+}
+
+
+static struct writequeue_entry *new_writequeue_entry(int 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;
+
+	return entry;
+}
+
+void *dlm_lowcomms_get_buffer(int nodeid, int len, int allocation, char **ppc)
+{
+	struct writequeue_entry *e;
+	int offset = 0;
+	int users = 0;
+	struct nodeinfo *ni;
+
+	if (!atomic_read(&accepting))
+		return NULL;
+
+	ni = nodeid2nodeinfo(nodeid, allocation);
+	if (!ni)
+		return NULL;
+
+	spin_lock(&ni->writequeue_lock);
+	e = list_entry(ni->writequeue.prev, struct writequeue_entry, list);
+	if (((struct list_head *) e == &ni->writequeue) ||
+	    (PAGE_CACHE_SIZE - e->end < len)) {
+		e = NULL;
+	} else {
+		offset = e->end;
+		e->end += len;
+		users = e->users++;
+	}
+	spin_unlock(&ni->writequeue_lock);
+
+	if (e) {
+	      got_one:
+		if (users == 0)
+			kmap(e->page);
+		*ppc = page_address(e->page) + offset;
+		return e;
+	}
+
+	e = new_writequeue_entry(allocation);
+	if (e) {
+		spin_lock(&ni->writequeue_lock);
+		offset = e->end;
+		e->end += len;
+		e->ni = ni;
+		users = e->users++;
+		list_add_tail(&e->list, &ni->writequeue);
+		spin_unlock(&ni->writequeue_lock);
+		goto got_one;
+	}
+	return NULL;
+}
+
+void dlm_lowcomms_commit_buffer(void *arg)
+{
+	struct writequeue_entry *e = (struct writequeue_entry *) arg;
+	int users;
+	struct nodeinfo *ni = e->ni;
+
+	if (!atomic_read(&accepting))
+		return;
+
+	spin_lock(&ni->writequeue_lock);
+	users = --e->users;
+	if (users)
+		goto out;
+	e->len = e->end - e->offset;
+	kunmap(e->page);
+	spin_unlock(&ni->writequeue_lock);
+
+	if (!test_and_set_bit(NI_WRITE_PENDING, &ni->flags)) {
+		spin_lock_bh(&write_nodes_lock);
+		list_add_tail(&ni->write_list, &write_nodes);
+		spin_unlock_bh(&write_nodes_lock);
+		wake_up_process(send_task);
+	}
+	return;
+
+      out:
+	spin_unlock(&ni->writequeue_lock);
+	return;
+}
+
+static void free_entry(struct writequeue_entry *e)
+{
+	__free_page(e->page);
+	kfree(e);
+}
+
+/* Initiate an SCTP association. In theory we could just use sendmsg() on
+   the first IP address and it should work, but this allows us to set up the
+   association before sending any valuable data that we can't afford to lose.
+   It also keeps the send path clean as it can now always use the association ID */
+static void initiate_association(int nodeid)
+{
+	struct sockaddr_storage rem_addr;
+	static char outcmsg[CMSG_SPACE(sizeof(struct sctp_sndrcvinfo))];
+	struct msghdr outmessage;
+	struct cmsghdr *cmsg;
+	struct sctp_sndrcvinfo *sinfo;
+	int ret;
+	int addrlen;
+	char buf[1];
+	struct kvec iov[1];
+	struct nodeinfo *ni;
+
+	log_print("Initiating association with node %d", nodeid);
+
+	ni = nodeid2nodeinfo(nodeid, GFP_KERNEL);
+	if (!ni)
+		return;
+
+	if (nodeid_to_addr(nodeid, (struct sockaddr *)&rem_addr)) {
+		log_print("no address for nodeid %d", nodeid);
+		return;
+	}
+
+	make_sockaddr(&rem_addr, dlm_config.tcp_port, &addrlen);
+
+	outmessage.msg_name = &rem_addr;
+	outmessage.msg_namelen = addrlen;
+	outmessage.msg_control = outcmsg;
+	outmessage.msg_controllen = sizeof(outcmsg);
+	outmessage.msg_flags = MSG_EOR;
+
+	iov[0].iov_base = buf;
+	iov[0].iov_len = 1;
+
+	/* Real INIT messages seem to cause trouble. Just send a 1 byte message
+	   we can afford to lose */
+	cmsg = CMSG_FIRSTHDR(&outmessage);
+	cmsg->cmsg_level = IPPROTO_SCTP;
+	cmsg->cmsg_type = SCTP_SNDRCV;
+	cmsg->cmsg_len = CMSG_LEN(sizeof(struct sctp_sndrcvinfo));
+	sinfo = (struct sctp_sndrcvinfo *)CMSG_DATA(cmsg);
+	memset(sinfo, 0x00, sizeof(struct sctp_sndrcvinfo));
+	sinfo->sinfo_ppid = cpu_to_le32(dlm_local_nodeid);
+
+	outmessage.msg_controllen = cmsg->cmsg_len;
+	ret = kernel_sendmsg(sctp_con.sock, &outmessage, iov, 1, 1);
+	if (ret < 0) {
+		log_print("send INIT to node failed: %d", ret);
+		/* Try again later */
+		clear_bit(NI_INIT_PENDING, &ni->flags);
+	}
+}
+
+/* Send a message */
+static int send_to_sock(struct nodeinfo *ni)
+{
+	int ret = 0;
+	struct writequeue_entry *e;
+	int len, offset;
+	struct msghdr outmsg;
+	static char outcmsg[CMSG_SPACE(sizeof(struct sctp_sndrcvinfo))];
+	struct cmsghdr *cmsg;
+	struct sctp_sndrcvinfo *sinfo;
+	struct kvec iov;
+
+        /* See if we need to init an association before we start
+	   sending precious messages */
+	spin_lock(&ni->lock);
+	if (!ni->assoc_id && !test_and_set_bit(NI_INIT_PENDING, &ni->flags)) {
+		spin_unlock(&ni->lock);
+		initiate_association(ni->nodeid);
+		return 0;
+	}
+	spin_unlock(&ni->lock);
+
+	outmsg.msg_name = NULL; /* We use assoc_id */
+	outmsg.msg_namelen = 0;
+	outmsg.msg_control = outcmsg;
+	outmsg.msg_controllen = sizeof(outcmsg);
+	outmsg.msg_flags = MSG_DONTWAIT | MSG_NOSIGNAL | MSG_EOR;
+
+	cmsg = CMSG_FIRSTHDR(&outmsg);
+	cmsg->cmsg_level = IPPROTO_SCTP;
+	cmsg->cmsg_type = SCTP_SNDRCV;
+	cmsg->cmsg_len = CMSG_LEN(sizeof(struct sctp_sndrcvinfo));
+	sinfo = (struct sctp_sndrcvinfo *)CMSG_DATA(cmsg);
+	memset(sinfo, 0x00, sizeof(struct sctp_sndrcvinfo));
+	sinfo->sinfo_ppid = cpu_to_le32(dlm_local_nodeid);
+	sinfo->sinfo_assoc_id = ni->assoc_id;
+	outmsg.msg_controllen = cmsg->cmsg_len;
+
+	spin_lock(&ni->writequeue_lock);
+	for (;;) {
+		if (list_empty(&ni->writequeue))
+			break;
+		e = list_entry(ni->writequeue.next, struct writequeue_entry,
+			       list);
+		len = e->len;
+		offset = e->offset;
+		BUG_ON(len == 0 && e->users == 0);
+		spin_unlock(&ni->writequeue_lock);
+		kmap(e->page);
+
+		ret = 0;
+		if (len) {
+			iov.iov_base = page_address(e->page)+offset;
+			iov.iov_len = len;
+
+			ret = kernel_sendmsg(sctp_con.sock, &outmsg, &iov, 1,
+					     len);
+			if (ret == -EAGAIN) {
+				sctp_con.eagain_flag = 1;
+				goto out;
+			} else if (ret < 0)
+				goto send_error;
+		} else {
+			/* Don't starve people filling buffers */
+			schedule();
+		}
+
+		spin_lock(&ni->writequeue_lock);
+		e->offset += ret;
+		e->len -= ret;
+
+		if (e->len == 0 && e->users == 0) {
+			list_del(&e->list);
+			free_entry(e);
+			continue;
+		}
+	}
+	spin_unlock(&ni->writequeue_lock);
+ out:
+	return ret;
+
+ send_error:
+	log_print("Error sending to node %d %d", ni->nodeid, ret);
+	spin_lock(&ni->lock);
+	if (!test_and_set_bit(NI_INIT_PENDING, &ni->flags)) {
+		ni->assoc_id = 0;
+		spin_unlock(&ni->lock);
+		initiate_association(ni->nodeid);
+	} else
+		spin_unlock(&ni->lock);
+
+	return ret;
+}
+
+/* Try to send any messages that are pending */
+static void process_output_queue(void)
+{
+	struct list_head *list;
+	struct list_head *temp;
+
+	spin_lock_bh(&write_nodes_lock);
+	list_for_each_safe(list, temp, &write_nodes) {
+		struct nodeinfo *ni =
+		    list_entry(list, struct nodeinfo, write_list);
+		clear_bit(NI_WRITE_PENDING, &ni->flags);
+		list_del(&ni->write_list);
+
+		spin_unlock_bh(&write_nodes_lock);
+
+		send_to_sock(ni);
+		spin_lock_bh(&write_nodes_lock);
+	}
+	spin_unlock_bh(&write_nodes_lock);
+}
+
+/* Called after we've had -EAGAIN and been woken up */
+static void refill_write_queue(void)
+{
+	int i;
+
+	for (i=1; i<=max_nodeid; i++) {
+		struct nodeinfo *ni = nodeid2nodeinfo(i, 0);
+
+		if (ni) {
+			if (!test_and_set_bit(NI_WRITE_PENDING, &ni->flags)) {
+				spin_lock_bh(&write_nodes_lock);
+				list_add_tail(&ni->write_list, &write_nodes);
+				spin_unlock_bh(&write_nodes_lock);
+			}
+		}
+	}
+}
+
+static void clean_one_writequeue(struct nodeinfo *ni)
+{
+	struct list_head *list;
+	struct list_head *temp;
+
+	spin_lock(&ni->writequeue_lock);
+	list_for_each_safe(list, temp, &ni->writequeue) {
+		struct writequeue_entry *e =
+			list_entry(list, struct writequeue_entry, list);
+		list_del(&e->list);
+		free_entry(e);
+	}
+	spin_unlock(&ni->writequeue_lock);
+}
+
+static void clean_writequeues(void)
+{
+	int i;
+
+	for (i=1; i<=max_nodeid; i++) {
+		struct nodeinfo *ni = nodeid2nodeinfo(i, 0);
+		if (ni)
+			clean_one_writequeue(ni);
+	}
+}
+
+
+static void dealloc_nodeinfo(void)
+{
+	int i;
+
+	for (i=1; i<=max_nodeid; i++) {
+		struct nodeinfo *ni = nodeid2nodeinfo(i, 0);
+		if (ni) {
+			idr_remove(&nodeinfo_idr, i);
+			kfree(ni);
+		}
+	}
+}
+
+int dlm_lowcomms_close(int nodeid)
+{
+	struct nodeinfo *ni;
+
+	ni = nodeid2nodeinfo(nodeid, 0);
+	if (!ni)
+		return -1;
+
+	spin_lock(&ni->lock);
+	if (ni->assoc_id) {
+		ni->assoc_id = 0;
+		/* Don't send shutdown here, sctp will just queue it
+		   till the node comes back up! */
+	}
+	spin_unlock(&ni->lock);
+
+	clean_one_writequeue(ni);
+	clear_bit(NI_INIT_PENDING, &ni->flags);
+	return 0;
+}
+
+static int write_list_empty(void)
+{
+	int status;
+
+	spin_lock_bh(&write_nodes_lock);
+	status = list_empty(&write_nodes);
+	spin_unlock_bh(&write_nodes_lock);
+
+	return status;
+}
+
+static int dlm_recvd(void *data)
+{
+	DECLARE_WAITQUEUE(wait, current);
+
+	while (!kthread_should_stop()) {
+		int count = 0;
+
+		set_current_state(TASK_INTERRUPTIBLE);
+		add_wait_queue(&lowcomms_recv_wait, &wait);
+		if (!test_bit(CF_READ_PENDING, &sctp_con.flags))
+			schedule();
+		remove_wait_queue(&lowcomms_recv_wait, &wait);
+		set_current_state(TASK_RUNNING);
+
+		if (test_and_clear_bit(CF_READ_PENDING, &sctp_con.flags)) {
+			int ret;
+
+			do {
+				ret = receive_from_sock();
+
+				/* Don't starve out everyone else */
+				if (++count >= MAX_RX_MSG_COUNT) {
+					schedule();
+					count = 0;
+				}
+			} while (!kthread_should_stop() && ret >=0);
+		}
+		schedule();
+	}
+
+	return 0;
+}
+
+static int dlm_sendd(void *data)
+{
+	DECLARE_WAITQUEUE(wait, current);
+
+	add_wait_queue(sctp_con.sock->sk->sk_sleep, &wait);
+
+	while (!kthread_should_stop()) {
+		set_current_state(TASK_INTERRUPTIBLE);
+		if (write_list_empty())
+			schedule();
+		set_current_state(TASK_RUNNING);
+
+		if (sctp_con.eagain_flag) {
+			sctp_con.eagain_flag = 0;
+			refill_write_queue();
+		}
+		process_output_queue();
+	}
+
+	remove_wait_queue(sctp_con.sock->sk->sk_sleep, &wait);
+
+	return 0;
+}
+
+static void daemons_stop(void)
+{
+	kthread_stop(recv_task);
+	kthread_stop(send_task);
+}
+
+static int daemons_start(void)
+{
+	struct task_struct *p;
+	int error;
+
+	p = kthread_run(dlm_recvd, NULL, "dlm_recvd");
+	error = IS_ERR(p);
+       	if (error) {
+		log_print("can't start dlm_recvd %d", error);
+		return error;
+	}
+	recv_task = p;
+
+	p = kthread_run(dlm_sendd, NULL, "dlm_sendd");
+	error = IS_ERR(p);
+       	if (error) {
+		log_print("can't start dlm_sendd %d", error);
+		kthread_stop(recv_task);
+		return error;
+	}
+	send_task = p;
+
+	return 0;
+}
+
+/*
+ * This is quite likely to sleep...
+ */
+int dlm_lowcomms_start(void)
+{
+	int error;
+
+	error = init_sock();
+	if (error)
+		goto fail_sock;
+	error = daemons_start();
+	if (error)
+		goto fail_sock;
+	atomic_set(&accepting, 1);
+	return 0;
+
+ fail_sock:
+	close_connection();
+	return error;
+}
+
+/* Set all the activity flags to prevent any socket activity. */
+
+void dlm_lowcomms_stop(void)
+{
+	atomic_set(&accepting, 0);
+	sctp_con.flags = 0x7;
+	daemons_stop();
+	clean_writequeues();
+	close_connection();
+	dealloc_nodeinfo();
+	max_nodeid = 0;
+}
+
+int dlm_lowcomms_init(void)
+{
+	init_waitqueue_head(&lowcomms_recv_wait);
+	spin_lock_init(&write_nodes_lock);
+	INIT_LIST_HEAD(&write_nodes);
+	init_rwsem(&nodeinfo_lock);
+	return 0;
+}
+
+void dlm_lowcomms_exit(void)
+{
+	int i;
+
+	for (i = 0; i < dlm_local_count; i++)
+		kfree(dlm_local_addr[i]);
+	dlm_local_count = 0;
+	dlm_local_nodeid = 0;
+}
+
Index: latest/fs/dlm/lowcomms-tcp.c
===================================================================
--- /dev/null
+++ latest/fs/dlm/lowcomms-tcp.c
@@ -0,0 +1,1262 @@
+/******************************************************************************
+*******************************************************************************
+**
+**  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
+**  Copyright (C) 2004-2006 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 base;
+	unsigned len;
+	unsigned mask;
+};
+
+#ifndef FALSE
+#define FALSE 0
+#define TRUE 1
+#endif
+#define NODE_INCREMENT 32
+
+#define CBUF_INIT(cb, size) do { (cb)->base = (cb)->len = 0; (cb)->mask = ((size)-1); } while(0)
+#define CBUF_ADD(cb, n) do { (cb)->len += n; } while(0)
+#define CBUF_EMPTY(cb) ((cb)->len == 0)
+#define CBUF_MAY_ADD(cb, n) (((cb)->len + (n)) < ((cb)->mask + 1))
+#define CBUF_EAT(cb, n) do { (cb)->len  -= (n); \
+                             (cb)->base += (n); (cb)->base &= (cb)->mask; } while(0)
+#define CBUF_DATA(cb) (((cb)->base + (cb)->len) & (cb)->mask)
+
+/* Maximum number of incoming messages to process before
+   doing a schedule()
+*/
+#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 rw_semaphore sock_sem;	/* Stop connect races */
+	struct list_head read_list;	/* On this list when ready for reading */
+	struct list_head write_list;	/* On this list when ready for writing */
+	struct list_head state_list;	/* On this list when ready to connect */
+	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;
+	atomic_t waiting_requests;
+#define MAX_CONNECT_RETRIES 3
+	struct connection *othercon;
+};
+#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;
+
+/* Manage daemons */
+static struct task_struct *recv_task;
+static struct task_struct *send_task;
+
+static wait_queue_t lowcomms_send_waitq_head;
+static wait_queue_head_t lowcomms_send_waitq;
+static wait_queue_t lowcomms_recv_waitq_head;
+static wait_queue_head_t lowcomms_recv_waitq;
+
+/* An array of pointers to connections, indexed by NODEID */
+static struct connection **connections;
+static struct semaphore connections_lock;
+static kmem_cache_t *con_cache;
+static int conn_array_size;
+static atomic_t accepting;
+
+/* List of sockets that have reads pending */
+static struct list_head read_sockets;
+static spinlock_t read_sockets_lock;
+
+/* List of sockets which have writes pending */
+static struct list_head write_sockets;
+static spinlock_t write_sockets_lock;
+
+/* List of sockets which have connects pending */
+static struct list_head state_sockets;
+static spinlock_t state_sockets_lock;
+
+static struct connection *nodeid2con(int nodeid, int 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 = kmalloc(sizeof(struct connection *) *
+				    new_size, allocation);
+		if (!new_conns)
+			goto finish;
+
+		memset(new_conns, 0, sizeof(struct connection *) * new_size);
+		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_alloc(con_cache, allocation);
+		if (!con)
+			goto finish;
+
+		memset(con, 0, sizeof(*con));
+		con->nodeid = nodeid;
+		init_rwsem(&con->sock_sem);
+		INIT_LIST_HEAD(&con->writequeue);
+		spin_lock_init(&con->writequeue_lock);
+
+		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);
+
+	atomic_inc(&con->waiting_requests);
+	if (test_and_set_bit(CF_READ_PENDING, &con->flags))
+		return;
+
+	spin_lock_bh(&read_sockets_lock);
+	list_add_tail(&con->read_list, &read_sockets);
+	spin_unlock_bh(&read_sockets_lock);
+
+	wake_up_interruptible(&lowcomms_recv_waitq);
+}
+
+static void lowcomms_write_space(struct sock *sk)
+{
+	struct connection *con = sock2con(sk);
+
+	if (test_and_set_bit(CF_WRITE_PENDING, &con->flags))
+		return;
+
+	spin_lock_bh(&write_sockets_lock);
+	list_add_tail(&con->write_list, &write_sockets);
+	spin_unlock_bh(&write_sockets_lock);
+
+	wake_up_interruptible(&lowcomms_send_waitq);
+}
+
+static inline void lowcomms_connect_sock(struct connection *con)
+{
+	if (test_and_set_bit(CF_CONNECT_PENDING, &con->flags))
+		return;
+	if (!atomic_read(&accepting))
+		return;
+
+	spin_lock_bh(&state_sockets_lock);
+	list_add_tail(&con->state_list, &state_sockets);
+	spin_unlock_bh(&state_sockets_lock);
+
+	wake_up_interruptible(&lowcomms_send_waitq);
+}
+
+static void lowcomms_state_change(struct sock *sk)
+{
+/*	struct connection *con = sock2con(sk); */
+
+	switch (sk->sk_state) {
+	case TCP_ESTABLISHED:
+		lowcomms_write_space(sk);
+		break;
+
+	case TCP_FIN_WAIT1:
+	case TCP_FIN_WAIT2:
+	case TCP_TIME_WAIT:
+	case TCP_CLOSE:
+	case TCP_CLOSE_WAIT:
+	case TCP_LAST_ACK:
+	case TCP_CLOSING:
+		/* FIXME: I think this causes more trouble than it solves.
+		   lowcomms wil reconnect anyway when there is something to
+		   send. This just attempts reconnection if a node goes down!
+		*/
+		/* lowcomms_connect_sock(con); */
+		break;
+
+	default:
+		printk("dlm: lowcomms_state_change: state=%d\n", sk->sk_state);
+		break;
+	}
+}
+
+/* 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, int and_other)
+{
+	down_write(&con->sock_sem);
+
+	if (con->sock) {
+		sock_release(con->sock);
+		con->sock = NULL;
+	}
+	if (con->othercon && and_other) {
+		/* Argh! recursion in kernel code!
+		   Actually, this isn't a list so it
+		   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;
+	up_write(&con->sock_sem);
+}
+
+/* Data received from remote end */
+static int receive_from_sock(struct connection *con)
+{
+	int ret = 0;
+	struct msghdr msg;
+	struct iovec iov[2];
+	mm_segment_t fs;
+	unsigned len;
+	int r;
+	int call_again_soon = 0;
+
+	down_read(&con->sock_sem);
+
+	if (con->sock == NULL)
+		goto out;
+	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);
+	}
+
+	msg.msg_control = NULL;
+	msg.msg_controllen = 0;
+	msg.msg_iovlen = 1;
+	msg.msg_iov = iov;
+	msg.msg_name = NULL;
+	msg.msg_namelen = 0;
+	msg.msg_flags = 0;
+
+	/*
+	 * 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;
+
+	/*
+	 * 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);
+		msg.msg_iovlen = 2;
+	}
+	len = iov[0].iov_len + iov[1].iov_len;
+
+	fs = get_fs();
+	set_fs(get_ds());
+	r = ret = sock_recvmsg(con->sock, &msg, len,
+			       MSG_DONTWAIT | MSG_NOSIGNAL);
+	set_fs(fs);
+
+	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;
+	}
+
+      out:
+	if (call_again_soon)
+		goto out_resched;
+	up_read(&con->sock_sem);
+	ret = 0;
+	goto out_ret;
+
+      out_resched:
+	lowcomms_data_ready(con->sock->sk, 0);
+	up_read(&con->sock_sem);
+	ret = 0;
+	schedule();
+	goto out_ret;
+
+      out_close:
+	up_read(&con->sock_sem);
+	if (ret != -EAGAIN && !test_bit(CF_IS_OTHERCON, &con->flags)) {
+		close_connection(con, FALSE);
+		/* Reconnect when there is something to send */
+	}
+
+      out_ret:
+	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;
+
+	memset(&peeraddr, 0, sizeof(peeraddr));
+	result = sock_create_kern(dlm_local_addr.ss_family, SOCK_STREAM, IPPROTO_TCP, &newsock);
+	if (result < 0)
+		return -ENOMEM;
+
+	down_read(&con->sock_sem);
+
+	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);
+		up_read(&con->sock_sem);
+		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;
+	}
+	down_write(&newcon->sock_sem);
+	if (newcon->sock) {
+	        struct connection *othercon = newcon->othercon;
+
+		if (!othercon) {
+			othercon = kmem_cache_alloc(con_cache, GFP_KERNEL);
+			if (!othercon) {
+				printk("dlm: failed to allocate incoming socket\n");
+				up_write(&newcon->sock_sem);
+				result = -ENOMEM;
+				goto accept_err;
+			}
+			memset(othercon, 0, sizeof(*othercon));
+			othercon->nodeid = nodeid;
+			othercon->rx_action = receive_from_sock;
+			init_rwsem(&othercon->sock_sem);
+			set_bit(CF_IS_OTHERCON, &othercon->flags);
+			newcon->othercon = othercon;
+		}
+		othercon->sock = newsock;
+		newsock->sk->sk_user_data = othercon;
+		add_sock(newsock, othercon);
+	}
+	else {
+		newsock->sk->sk_user_data = newcon;
+		newcon->rx_action = receive_from_sock;
+		add_sock(newsock, newcon);
+
+	}
+
+	up_write(&newcon->sock_sem);
+
+	/*
+	 * Add it to the active queue in case we got data
+	 * beween processing the accept adding the socket
+	 * to the read_sockets list
+	 */
+	lowcomms_data_ready(newsock->sk, 0);
+	up_read(&con->sock_sem);
+
+	return 0;
+
+      accept_err:
+	up_read(&con->sock_sem);
+	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 int 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 0;
+	}
+
+	down_write(&con->sock_sem);
+	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.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_err;
+
+      out:
+	up_write(&con->sock_sem);
+	/*
+	 * Returning an error here means we've given up trying to connect to
+	 * a remote node, otherwise we return 0 and reschedule the connetion
+	 * attempt
+	 */
+	return result;
+
+      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;
+	}
+	goto out;
+}
+
+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.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.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.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 */
+	memset(con, 0, sizeof(*con));
+	init_rwsem(&con->sock_sem);
+	spin_lock_init(&con->writequeue_lock);
+	INIT_LIST_HEAD(&con->writequeue);
+	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,
+						     int 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,
+			      int allocation, char **ppc)
+{
+	struct connection *con;
+	struct writequeue_entry *e;
+	int offset = 0;
+	int users = 0;
+
+	if (!atomic_read(&accepting))
+		return NULL;
+
+	con = nodeid2con(nodeid, allocation);
+	if (!con)
+		return NULL;
+
+	spin_lock(&con->writequeue_lock);
+	e = list_entry(con->writequeue.prev, struct writequeue_entry, list);
+	if (((struct list_head *) e == &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;
+
+	if (!atomic_read(&accepting))
+		return;
+
+	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) == 0) {
+		spin_lock_bh(&write_sockets_lock);
+		list_add_tail(&con->write_list, &write_sockets);
+		spin_unlock_bh(&write_sockets_lock);
+
+		wake_up_interruptible(&lowcomms_send_waitq);
+	}
+	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 int 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;
+
+	down_read(&con->sock_sem);
+	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);
+
+		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 */
+			schedule();
+		}
+
+		spin_lock(&con->writequeue_lock);
+		e->offset += ret;
+		e->len -= ret;
+
+		if (e->len == 0 && e->users == 0) {
+			list_del(&e->list);
+			free_entry(e);
+			continue;
+		}
+	}
+	spin_unlock(&con->writequeue_lock);
+      out:
+	up_read(&con->sock_sem);
+	return ret;
+
+      send_error:
+	up_read(&con->sock_sem);
+	close_connection(con, FALSE);
+	lowcomms_connect_sock(con);
+	return ret;
+
+      out_connect:
+	up_read(&con->sock_sem);
+	lowcomms_connect_sock(con);
+	return 0;
+}
+
+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);
+		atomic_set(&con->waiting_requests, 0);
+	}
+	return 0;
+
+      out:
+	return -1;
+}
+
+/* API send message call, may queue the request */
+/* N.B. This is the old interface - use the new one for new calls */
+int lowcomms_send_message(int nodeid, char *buf, int len, int allocation)
+{
+	struct writequeue_entry *e;
+	char *b;
+
+	e = dlm_lowcomms_get_buffer(nodeid, len, allocation, &b);
+	if (e) {
+		memcpy(b, buf, len);
+		dlm_lowcomms_commit_buffer(e);
+		return 0;
+	}
+	return -ENOBUFS;
+}
+
+/* Look for activity on active sockets */
+static void process_sockets(void)
+{
+	struct list_head *list;
+	struct list_head *temp;
+	int count = 0;
+
+	spin_lock_bh(&read_sockets_lock);
+	list_for_each_safe(list, temp, &read_sockets) {
+
+		struct connection *con =
+		    list_entry(list, struct connection, read_list);
+		list_del(&con->read_list);
+		clear_bit(CF_READ_PENDING, &con->flags);
+
+		spin_unlock_bh(&read_sockets_lock);
+
+		/* This can reach zero if we are processing requests
+		 * as they come in.
+		 */
+		if (atomic_read(&con->waiting_requests) == 0) {
+			spin_lock_bh(&read_sockets_lock);
+			continue;
+		}
+
+		do {
+			con->rx_action(con);
+
+			/* Don't starve out everyone else */
+			if (++count >= MAX_RX_MSG_COUNT) {
+				schedule();
+				count = 0;
+			}
+
+		} while (!atomic_dec_and_test(&con->waiting_requests) &&
+			 !kthread_should_stop());
+
+		spin_lock_bh(&read_sockets_lock);
+	}
+	spin_unlock_bh(&read_sockets_lock);
+}
+
+/* Try to send any messages that are pending
+ */
+static void process_output_queue(void)
+{
+	struct list_head *list;
+	struct list_head *temp;
+	int ret;
+
+	spin_lock_bh(&write_sockets_lock);
+	list_for_each_safe(list, temp, &write_sockets) {
+		struct connection *con =
+		    list_entry(list, struct connection, write_list);
+		clear_bit(CF_WRITE_PENDING, &con->flags);
+		list_del(&con->write_list);
+
+		spin_unlock_bh(&write_sockets_lock);
+
+		ret = send_to_sock(con);
+		if (ret < 0) {
+		}
+		spin_lock_bh(&write_sockets_lock);
+	}
+	spin_unlock_bh(&write_sockets_lock);
+}
+
+static void process_state_queue(void)
+{
+	struct list_head *list;
+	struct list_head *temp;
+	int ret;
+
+	spin_lock_bh(&state_sockets_lock);
+	list_for_each_safe(list, temp, &state_sockets) {
+		struct connection *con =
+		    list_entry(list, struct connection, state_list);
+		list_del(&con->state_list);
+		clear_bit(CF_CONNECT_PENDING, &con->flags);
+		spin_unlock_bh(&state_sockets_lock);
+
+		ret = connect_to_sock(con);
+		if (ret < 0) {
+		}
+		spin_lock_bh(&state_sockets_lock);
+	}
+	spin_unlock_bh(&state_sockets_lock);
+}
+
+
+/* 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 int read_list_empty(void)
+{
+	int status;
+
+	spin_lock_bh(&read_sockets_lock);
+	status = list_empty(&read_sockets);
+	spin_unlock_bh(&read_sockets_lock);
+
+	return status;
+}
+
+/* DLM Transport comms receive daemon */
+static int dlm_recvd(void *data)
+{
+	init_waitqueue_head(&lowcomms_recv_waitq);
+	init_waitqueue_entry(&lowcomms_recv_waitq_head, current);
+	add_wait_queue(&lowcomms_recv_waitq, &lowcomms_recv_waitq_head);
+
+	while (!kthread_should_stop()) {
+		set_current_state(TASK_INTERRUPTIBLE);
+		if (read_list_empty())
+			schedule();
+		set_current_state(TASK_RUNNING);
+
+		process_sockets();
+	}
+
+	return 0;
+}
+
+static int write_and_state_lists_empty(void)
+{
+	int status;
+
+	spin_lock_bh(&write_sockets_lock);
+	status = list_empty(&write_sockets);
+	spin_unlock_bh(&write_sockets_lock);
+
+	spin_lock_bh(&state_sockets_lock);
+	if (list_empty(&state_sockets) == 0)
+		status = 0;
+	spin_unlock_bh(&state_sockets_lock);
+
+	return status;
+}
+
+/* DLM Transport send daemon */
+static int dlm_sendd(void *data)
+{
+	init_waitqueue_head(&lowcomms_send_waitq);
+	init_waitqueue_entry(&lowcomms_send_waitq_head, current);
+	add_wait_queue(&lowcomms_send_waitq, &lowcomms_send_waitq_head);
+
+	while (!kthread_should_stop()) {
+		set_current_state(TASK_INTERRUPTIBLE);
+		if (write_and_state_lists_empty())
+			schedule();
+		set_current_state(TASK_RUNNING);
+
+		process_state_queue();
+		process_output_queue();
+	}
+
+	return 0;
+}
+
+static void daemons_stop(void)
+{
+	kthread_stop(recv_task);
+	kthread_stop(send_task);
+}
+
+static int daemons_start(void)
+{
+	struct task_struct *p;
+	int error;
+
+	p = kthread_run(dlm_recvd, NULL, "dlm_recvd");
+	error = IS_ERR(p);
+       	if (error) {
+		log_print("can't start dlm_recvd %d", error);
+		return error;
+	}
+	recv_task = p;
+
+	p = kthread_run(dlm_sendd, NULL, "dlm_sendd");
+	error = IS_ERR(p);
+       	if (error) {
+		log_print("can't start dlm_sendd %d", error);
+		kthread_stop(recv_task);
+		return error;
+	}
+	send_task = p;
+
+	return 0;
+}
+
+/*
+ * Return the largest buffer size we can cope with.
+ */
+int lowcomms_max_buffer_size(void)
+{
+	return PAGE_CACHE_SIZE;
+}
+
+void dlm_lowcomms_stop(void)
+{
+	int i;
+
+	atomic_set(&accepting, 0);
+
+	/* Set all the activity flags to prevent any
+	   socket activity.
+	*/
+	for (i = 0; i < conn_array_size; i++) {
+		if (connections[i])
+			connections[i]->flags |= 0x7;
+	}
+	daemons_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 = -ENOTCONN;
+
+	/*
+	 * Temporarily initialise the waitq head so that lowcomms_send_message
+	 * doesn't crash if it gets called before the thread is fully
+	 * initialised
+	 */
+	init_waitqueue_head(&lowcomms_send_waitq);
+
+	error = -ENOMEM;
+	connections = kmalloc(sizeof(struct connection *) *
+			      NODE_INCREMENT, GFP_KERNEL);
+	if (!connections)
+		goto out;
+
+	memset(connections, 0,
+	       sizeof(struct connection *) * NODE_INCREMENT);
+
+	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 = daemons_start();
+	if (error)
+		goto fail_unlisten;
+
+	atomic_set(&accepting, 1);
+
+	return 0;
+
+      fail_unlisten:
+	close_connection(connections[0], 0);
+	kmem_cache_free(con_cache, connections[0]);
+	kmem_cache_destroy(con_cache);
+
+      fail_free_conn:
+	kfree(connections);
+
+      out:
+	return error;
+}
+
+int dlm_lowcomms_init(void)
+{
+	INIT_LIST_HEAD(&read_sockets);
+	INIT_LIST_HEAD(&write_sockets);
+	INIT_LIST_HEAD(&state_sockets);
+
+	spin_lock_init(&read_sockets_lock);
+	spin_lock_init(&write_sockets_lock);
+	spin_lock_init(&state_sockets_lock);
+	init_MUTEX(&connections_lock);
+
+	return 0;
+}
+
+void dlm_lowcomms_exit(void)
+{
+	/* Nothing to do here,
+	   needed for compatibility with the sctp version
+	*/
+}
+
+/* Don't accept any more outgoing work */
+void lowcomms_stop_accept(void)
+{
+        atomic_set(&accepting, 0);
+}
+
Index: latest/fs/dlm/lowcomms.c
===================================================================
--- latest.orig/fs/dlm/lowcomms.c
+++ /dev/null
@@ -1,1238 +0,0 @@
-/******************************************************************************
-*******************************************************************************
-**
-**  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
-**  Copyright (C) 2004-2005 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 (well, hardly ever) waits.
- *
- */
-
-#include <asm/ioctls.h>
-#include <net/sock.h>
-#include <net/tcp.h>
-#include <net/sctp/user.h>
-#include <linux/pagemap.h>
-#include <linux/socket.h>
-#include <linux/idr.h>
-
-#include "dlm_internal.h"
-#include "lowcomms.h"
-#include "config.h"
-#include "midcomms.h"
-
-static struct sockaddr_storage *dlm_local_addr[DLM_MAX_ADDR_COUNT];
-static int			dlm_local_count;
-static int			dlm_local_nodeid;
-
-/* One of these per connected node */
-
-#define NI_INIT_PENDING 1
-#define NI_WRITE_PENDING 2
-
-struct nodeinfo {
-	spinlock_t		lock;
-	sctp_assoc_t		assoc_id;
-	unsigned long		flags;
-	struct list_head	write_list; /* nodes with pending writes */
-	struct list_head	writequeue; /* outgoing writequeue_entries */
-	spinlock_t		writequeue_lock;
-	int			nodeid;
-};
-
-static DEFINE_IDR(nodeinfo_idr);
-static struct rw_semaphore	nodeinfo_lock;
-static int			max_nodeid;
-
-struct cbuf {
-	unsigned		base;
-	unsigned		len;
-	unsigned		mask;
-};
-
-/* Just the one of these, now. But this struct keeps
-   the connection-specific variables together */
-
-#define CF_READ_PENDING 1
-
-struct connection {
-	struct socket          *sock;
-	unsigned long		flags;
-	struct page            *rx_page;
-	atomic_t		waiting_requests;
-	struct cbuf		cb;
-	int                     eagain_flag;
-};
-
-/* 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 nodeinfo        *ni;
-};
-
-#define CBUF_ADD(cb, n) do { (cb)->len += n; } while(0)
-#define CBUF_EMPTY(cb) ((cb)->len == 0)
-#define CBUF_MAY_ADD(cb, n) (((cb)->len + (n)) < ((cb)->mask + 1))
-#define CBUF_DATA(cb) (((cb)->base + (cb)->len) & (cb)->mask)
-
-#define CBUF_INIT(cb, size) \
-do { \
-	(cb)->base = (cb)->len = 0; \
-	(cb)->mask = ((size)-1); \
-} while(0)
-
-#define CBUF_EAT(cb, n) \
-do { \
-	(cb)->len  -= (n); \
-	(cb)->base += (n); \
-	(cb)->base &= (cb)->mask; \
-} while(0)
-
-
-/* List of nodes which have writes pending */
-static struct list_head write_nodes;
-static spinlock_t write_nodes_lock;
-
-/* Maximum number of incoming messages to process before
- * doing a schedule()
- */
-#define MAX_RX_MSG_COUNT 25
-
-/* Manage daemons */
-static struct task_struct *recv_task;
-static struct task_struct *send_task;
-static wait_queue_head_t lowcomms_recv_wait;
-static atomic_t accepting;
-
-/* The SCTP connection */
-static struct connection sctp_con;
-
-
-static int nodeid_to_addr(int nodeid, struct sockaddr *retaddr)
-{
-	struct sockaddr_storage addr;
-	int error;
-
-	if (!dlm_local_count)
-		return -1;
-
-	error = dlm_nodeid_to_addr(nodeid, &addr);
-	if (error)
-		return error;
-
-	if (dlm_local_addr[0]->ss_family == AF_INET) {
-	        struct sockaddr_in *in4  = (struct sockaddr_in *) &addr;
-		struct sockaddr_in *ret4 = (struct sockaddr_in *) retaddr;
-		ret4->sin_addr.s_addr = in4->sin_addr.s_addr;
-	} else {
-	        struct sockaddr_in6 *in6  = (struct sockaddr_in6 *) &addr;
-		struct sockaddr_in6 *ret6 = (struct sockaddr_in6 *) retaddr;
-		memcpy(&ret6->sin6_addr, &in6->sin6_addr,
-		       sizeof(in6->sin6_addr));
-	}
-
-	return 0;
-}
-
-static struct nodeinfo *nodeid2nodeinfo(int nodeid, int alloc)
-{
-	struct nodeinfo *ni;
-	int r;
-	int n;
-
-	down_read(&nodeinfo_lock);
-	ni = idr_find(&nodeinfo_idr, nodeid);
-	up_read(&nodeinfo_lock);
-
-	if (!ni && alloc) {
-		down_write(&nodeinfo_lock);
-
-		ni = idr_find(&nodeinfo_idr, nodeid);
-		if (ni)
-			goto out_up;
-
-		r = idr_pre_get(&nodeinfo_idr, alloc);
-		if (!r)
-			goto out_up;
-
-		ni = kmalloc(sizeof(struct nodeinfo), alloc);
-		if (!ni)
-			goto out_up;
-
-		r = idr_get_new_above(&nodeinfo_idr, ni, nodeid, &n);
-		if (r) {
-			kfree(ni);
-			ni = NULL;
-			goto out_up;
-		}
-		if (n != nodeid) {
-			idr_remove(&nodeinfo_idr, n);
-			kfree(ni);
-			ni = NULL;
-			goto out_up;
-		}
-		memset(ni, 0, sizeof(struct nodeinfo));
-		spin_lock_init(&ni->lock);
-		INIT_LIST_HEAD(&ni->writequeue);
-		spin_lock_init(&ni->writequeue_lock);
-		ni->nodeid = nodeid;
-
-		if (nodeid > max_nodeid)
-			max_nodeid = nodeid;
-	out_up:
-		up_write(&nodeinfo_lock);
-	}
-
-	return ni;
-}
-
-/* Don't call this too often... */
-static struct nodeinfo *assoc2nodeinfo(sctp_assoc_t assoc)
-{
-	int i;
-	struct nodeinfo *ni;
-
-	for (i=1; i<=max_nodeid; i++) {
-		ni = nodeid2nodeinfo(i, 0);
-		if (ni && ni->assoc_id == assoc)
-			return ni;
-	}
-	return NULL;
-}
-
-/* Data or notification available on socket */
-static void lowcomms_data_ready(struct sock *sk, int count_unused)
-{
-	atomic_inc(&sctp_con.waiting_requests);
-	if (test_and_set_bit(CF_READ_PENDING, &sctp_con.flags))
-		return;
-
-	wake_up_interruptible(&lowcomms_recv_wait);
-}
-
-
-/* Add the port number to an IP6 or 4 sockaddr and return the address length.
-   Also padd out the struct with zeros to make comparisons meaningful */
-
-static void make_sockaddr(struct sockaddr_storage *saddr, uint16_t port,
-			  int *addr_len)
-{
-	struct sockaddr_in *local4_addr;
-	struct sockaddr_in6 *local6_addr;
-
-	if (!dlm_local_count)
-		return;
-
-	if (!port) {
-		if (dlm_local_addr[0]->ss_family == AF_INET) {
-			local4_addr = (struct sockaddr_in *)dlm_local_addr[0];
-			port = be16_to_cpu(local4_addr->sin_port);
-		} else {
-			local6_addr = (struct sockaddr_in6 *)dlm_local_addr[0];
-			port = be16_to_cpu(local6_addr->sin6_port);
-		}
-	}
-
-	saddr->ss_family = dlm_local_addr[0]->ss_family;
-	if (dlm_local_addr[0]->ss_family == AF_INET) {
-		struct sockaddr_in *in4_addr = (struct sockaddr_in *)saddr;
-		in4_addr->sin_port = cpu_to_be16(port);
-		memset(&in4_addr->sin_zero, 0, sizeof(in4_addr->sin_zero));
-		memset(in4_addr+1, 0, sizeof(struct sockaddr_storage) -
-				      sizeof(struct sockaddr_in));
-		*addr_len = sizeof(struct sockaddr_in);
-	} else {
-		struct sockaddr_in6 *in6_addr = (struct sockaddr_in6 *)saddr;
-		in6_addr->sin6_port = cpu_to_be16(port);
-		memset(in6_addr+1, 0, sizeof(struct sockaddr_storage) -
-				      sizeof(struct sockaddr_in6));
-		*addr_len = sizeof(struct sockaddr_in6);
-	}
-}
-
-/* Close the connection and tidy up */
-static void close_connection(void)
-{
-	if (sctp_con.sock) {
-		sock_release(sctp_con.sock);
-		sctp_con.sock = NULL;
-	}
-
-	if (sctp_con.rx_page) {
-		__free_page(sctp_con.rx_page);
-		sctp_con.rx_page = NULL;
-	}
-}
-
-/* We only send shutdown messages to nodes that are not part of the cluster */
-static void send_shutdown(sctp_assoc_t associd)
-{
-	static char outcmsg[CMSG_SPACE(sizeof(struct sctp_sndrcvinfo))];
-	struct msghdr outmessage;
-	struct cmsghdr *cmsg;
-	struct sctp_sndrcvinfo *sinfo;
-	int ret;
-
-	outmessage.msg_name = NULL;
-	outmessage.msg_namelen = 0;
-	outmessage.msg_control = outcmsg;
-	outmessage.msg_controllen = sizeof(outcmsg);
-	outmessage.msg_flags = MSG_EOR;
-
-	cmsg = CMSG_FIRSTHDR(&outmessage);
-	cmsg->cmsg_level = IPPROTO_SCTP;
-	cmsg->cmsg_type = SCTP_SNDRCV;
-	cmsg->cmsg_len = CMSG_LEN(sizeof(struct sctp_sndrcvinfo));
-	outmessage.msg_controllen = cmsg->cmsg_len;
-	sinfo = (struct sctp_sndrcvinfo *)CMSG_DATA(cmsg);
-	memset(sinfo, 0x00, sizeof(struct sctp_sndrcvinfo));
-
-	sinfo->sinfo_flags |= MSG_EOF;
-	sinfo->sinfo_assoc_id = associd;
-
-	ret = kernel_sendmsg(sctp_con.sock, &outmessage, NULL, 0, 0);
-
-	if (ret != 0)
-		log_print("send EOF to node failed: %d", ret);
-}
-
-
-/* INIT failed but we don't know which node...
-   restart INIT on all pending nodes */
-static void init_failed(void)
-{
-	int i;
-	struct nodeinfo *ni;
-
-	for (i=1; i<=max_nodeid; i++) {
-		ni = nodeid2nodeinfo(i, 0);
-		if (!ni)
-			continue;
-
-		if (test_and_clear_bit(NI_INIT_PENDING, &ni->flags)) {
-			ni->assoc_id = 0;
-			if (!test_and_set_bit(NI_WRITE_PENDING, &ni->flags)) {
-				spin_lock_bh(&write_nodes_lock);
-				list_add_tail(&ni->write_list, &write_nodes);
-				spin_unlock_bh(&write_nodes_lock);
-			}
-		}
-	}
-	wake_up_process(send_task);
-}
-
-/* Something happened to an association */
-static void process_sctp_notification(struct msghdr *msg, char *buf)
-{
-	union sctp_notification *sn = (union sctp_notification *)buf;
-
-	if (sn->sn_header.sn_type == SCTP_ASSOC_CHANGE) {
-		switch (sn->sn_assoc_change.sac_state) {
-
-		case SCTP_COMM_UP:
-		case SCTP_RESTART:
-		{
-			/* Check that the new node is in the lockspace */
-			struct sctp_prim prim;
-			mm_segment_t fs;
-			int nodeid;
-			int prim_len, ret;
-			int addr_len;
-			struct nodeinfo *ni;
-
-			/* This seems to happen when we received a connection
-			 * too early... or something...  anyway, it happens but
-			 * we always seem to get a real message too, see
-			 * receive_from_sock */
-
-			if ((int)sn->sn_assoc_change.sac_assoc_id <= 0) {
-				log_print("COMM_UP for invalid assoc ID %d",
-					 (int)sn->sn_assoc_change.sac_assoc_id);
-				init_failed();
-				return;
-			}
-			memset(&prim, 0, sizeof(struct sctp_prim));
-			prim_len = sizeof(struct sctp_prim);
-			prim.ssp_assoc_id = sn->sn_assoc_change.sac_assoc_id;
-
-			fs = get_fs();
-			set_fs(get_ds());
-			ret = sctp_con.sock->ops->getsockopt(sctp_con.sock,
-						IPPROTO_SCTP, SCTP_PRIMARY_ADDR,
-						(char*)&prim, &prim_len);
-			set_fs(fs);
-			if (ret < 0) {
-				struct nodeinfo *ni;
-
-				log_print("getsockopt/sctp_primary_addr on "
-					  "new assoc %d failed : %d",
-				    (int)sn->sn_assoc_change.sac_assoc_id, ret);
-
-				/* Retry INIT later */
-				ni = assoc2nodeinfo(sn->sn_assoc_change.sac_assoc_id);
-				if (ni)
-					clear_bit(NI_INIT_PENDING, &ni->flags);
-				return;
-			}
-			make_sockaddr(&prim.ssp_addr, 0, &addr_len);
-			if (dlm_addr_to_nodeid(&prim.ssp_addr, &nodeid)) {
-				log_print("reject connect from unknown addr");
-				send_shutdown(prim.ssp_assoc_id);
-				return;
-			}
-
-			ni = nodeid2nodeinfo(nodeid, GFP_KERNEL);
-			if (!ni)
-				return;
-
-			/* Save the assoc ID */
-			spin_lock(&ni->lock);
-			ni->assoc_id = sn->sn_assoc_change.sac_assoc_id;
-			spin_unlock(&ni->lock);
-
-			log_print("got new/restarted association %d nodeid %d",
-			       (int)sn->sn_assoc_change.sac_assoc_id, nodeid);
-
-			/* Send any pending writes */
-			clear_bit(NI_INIT_PENDING, &ni->flags);
-			if (!test_and_set_bit(NI_WRITE_PENDING, &ni->flags)) {
-				spin_lock_bh(&write_nodes_lock);
-				list_add_tail(&ni->write_list, &write_nodes);
-				spin_unlock_bh(&write_nodes_lock);
-			}
-			wake_up_process(send_task);
-		}
-		break;
-
-		case SCTP_COMM_LOST:
-		case SCTP_SHUTDOWN_COMP:
-		{
-			struct nodeinfo *ni;
-
-			ni = assoc2nodeinfo(sn->sn_assoc_change.sac_assoc_id);
-			if (ni) {
-				spin_lock(&ni->lock);
-				ni->assoc_id = 0;
-				spin_unlock(&ni->lock);
-			}
-		}
-		break;
-
-		/* We don't know which INIT failed, so clear the PENDING flags
-		 * on them all.  if assoc_id is zero then it will then try
-		 * again */
-
-		case SCTP_CANT_STR_ASSOC:
-		{
-			log_print("Can't start SCTP association - retrying");
-			init_failed();
-		}
-		break;
-
-		default:
-			log_print("unexpected SCTP assoc change id=%d state=%d",
-				  (int)sn->sn_assoc_change.sac_assoc_id,
-				  sn->sn_assoc_change.sac_state);
-		}
-	}
-}
-
-/* Data received from remote end */
-static int receive_from_sock(void)
-{
-	int ret = 0;
-	struct msghdr msg;
-	struct kvec iov[2];
-	unsigned len;
-	int r;
-	struct sctp_sndrcvinfo *sinfo;
-	struct cmsghdr *cmsg;
-	struct nodeinfo *ni;
-
-	/* These two are marginally too big for stack allocation, but this
-	 * function is (currently) only called by dlm_recvd so static should be
-	 * OK.
-	 */
-	static struct sockaddr_storage msgname;
-	static char incmsg[CMSG_SPACE(sizeof(struct sctp_sndrcvinfo))];
-
-	if (sctp_con.sock == NULL)
-		goto out;
-
-	if (sctp_con.rx_page == NULL) {
-		/*
-		 * This doesn't need to be atomic, but I think it should
-		 * improve performance if it is.
-		 */
-		sctp_con.rx_page = alloc_page(GFP_ATOMIC);
-		if (sctp_con.rx_page == NULL)
-			goto out_resched;
-		CBUF_INIT(&sctp_con.cb, PAGE_CACHE_SIZE);
-	}
-
-	memset(&incmsg, 0, sizeof(incmsg));
-	memset(&msgname, 0, sizeof(msgname));
-
-	memset(incmsg, 0, sizeof(incmsg));
-	msg.msg_name = &msgname;
-	msg.msg_namelen = sizeof(msgname);
-	msg.msg_flags = 0;
-	msg.msg_control = incmsg;
-	msg.msg_controllen = sizeof(incmsg);
-
-	/* I don't see why this circular buffer stuff is necessary for SCTP
-	 * which is a packet-based protocol, but the whole thing breaks under
-	 * load without it! The overhead is minimal (and is in the TCP lowcomms
-	 * anyway, of course) so I'll leave it in until I can figure out what's
-	 * really happening.
-	 */
-
-	/*
-	 * 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 = sctp_con.cb.base - CBUF_DATA(&sctp_con.cb);
-	iov[0].iov_base = page_address(sctp_con.rx_page) +
-			  CBUF_DATA(&sctp_con.cb);
-	iov[1].iov_len = 0;
-
-	/*
-	 * 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(&sctp_con.cb) >= sctp_con.cb.base) {
-		iov[0].iov_len = PAGE_CACHE_SIZE - CBUF_DATA(&sctp_con.cb);
-		iov[1].iov_len = sctp_con.cb.base;
-		iov[1].iov_base = page_address(sctp_con.rx_page);
-		msg.msg_iovlen = 2;
-	}
-	len = iov[0].iov_len + iov[1].iov_len;
-
-	r = ret = kernel_recvmsg(sctp_con.sock, &msg, iov, msg.msg_iovlen, len,
-				 MSG_NOSIGNAL | MSG_DONTWAIT);
-	if (ret <= 0)
-		goto out_close;
-
-	msg.msg_control = incmsg;
-	msg.msg_controllen = sizeof(incmsg);
-	cmsg = CMSG_FIRSTHDR(&msg);
-	sinfo = (struct sctp_sndrcvinfo *)CMSG_DATA(cmsg);
-
-	if (msg.msg_flags & MSG_NOTIFICATION) {
-		process_sctp_notification(&msg, page_address(sctp_con.rx_page));
-		return 0;
-	}
-
-	/* Is this a new association ? */
-	ni = nodeid2nodeinfo(le32_to_cpu(sinfo->sinfo_ppid), GFP_KERNEL);
-	if (ni) {
-		ni->assoc_id = sinfo->sinfo_assoc_id;
-		if (test_and_clear_bit(NI_INIT_PENDING, &ni->flags)) {
-
-			if (!test_and_set_bit(NI_WRITE_PENDING, &ni->flags)) {
-				spin_lock_bh(&write_nodes_lock);
-				list_add_tail(&ni->write_list, &write_nodes);
-				spin_unlock_bh(&write_nodes_lock);
-			}
-			wake_up_process(send_task);
-		}
-	}
-
-	/* INIT sends a message with length of 1 - ignore it */
-	if (r == 1)
-		return 0;
-
-	CBUF_ADD(&sctp_con.cb, ret);
-	ret = dlm_process_incoming_buffer(cpu_to_le32(sinfo->sinfo_ppid),
-					  page_address(sctp_con.rx_page),
-					  sctp_con.cb.base, sctp_con.cb.len,
-					  PAGE_CACHE_SIZE);
-	if (ret < 0)
-		goto out_close;
-	CBUF_EAT(&sctp_con.cb, ret);
-
-      out:
-	ret = 0;
-	goto out_ret;
-
-      out_resched:
-	lowcomms_data_ready(sctp_con.sock->sk, 0);
-	ret = 0;
-	schedule();
-	goto out_ret;
-
-      out_close:
-	if (ret != -EAGAIN)
-		log_print("error reading from sctp socket: %d", ret);
-      out_ret:
-	return ret;
-}
-
-/* Bind to an IP address. SCTP allows multiple address so it can do multi-homing */
-static int add_bind_addr(struct sockaddr_storage *addr, int addr_len, int num)
-{
-	mm_segment_t fs;
-	int result = 0;
-
-	fs = get_fs();
-	set_fs(get_ds());
-	if (num == 1)
-		result = sctp_con.sock->ops->bind(sctp_con.sock,
-					(struct sockaddr *) addr, addr_len);
-	else
-		result = sctp_con.sock->ops->setsockopt(sctp_con.sock, SOL_SCTP,
-				SCTP_SOCKOPT_BINDX_ADD, (char *)addr, addr_len);
-	set_fs(fs);
-
-	if (result < 0)
-		log_print("Can't bind to port %d addr number %d",
-			  dlm_config.tcp_port, num);
-
-	return result;
-}
-
-static void init_local(void)
-{
-	struct sockaddr_storage sas, *addr;
-	int i;
-
-	dlm_local_nodeid = dlm_our_nodeid();
-
-	for (i = 0; i < DLM_MAX_ADDR_COUNT - 1; i++) {
-		if (dlm_our_addr(&sas, i))
-			break;
-
-		addr = kmalloc(sizeof(*addr), GFP_KERNEL);
-		if (!addr)
-			break;
-		memcpy(addr, &sas, sizeof(*addr));
-		dlm_local_addr[dlm_local_count++] = addr;
-	}
-}
-
-/* Initialise SCTP socket and bind to all interfaces */
-static int init_sock(void)
-{
-	mm_segment_t fs;
-	struct socket *sock = NULL;
-	struct sockaddr_storage localaddr;
-	struct sctp_event_subscribe subscribe;
-	int result = -EINVAL, num = 1, i, addr_len;
-
-	if (!dlm_local_count) {
-		init_local();
-		if (!dlm_local_count) {
-			log_print("no local IP address has been set");
-			goto out;
-		}
-	}
-
-	result = sock_create_kern(dlm_local_addr[0]->ss_family, SOCK_SEQPACKET,
-				  IPPROTO_SCTP, &sock);
-	if (result < 0) {
-		log_print("Can't create comms socket, check SCTP is loaded");
-		goto out;
-	}
-
-	/* Listen for events */
-	memset(&subscribe, 0, sizeof(subscribe));
-	subscribe.sctp_data_io_event = 1;
-	subscribe.sctp_association_event = 1;
-	subscribe.sctp_send_failure_event = 1;
-	subscribe.sctp_shutdown_event = 1;
-	subscribe.sctp_partial_delivery_event = 1;
-
-	fs = get_fs();
-	set_fs(get_ds());
-	result = sock->ops->setsockopt(sock, SOL_SCTP, SCTP_EVENTS,
-				       (char *)&subscribe, sizeof(subscribe));
-	set_fs(fs);
-
-	if (result < 0) {
-		log_print("Failed to set SCTP_EVENTS on socket: result=%d",
-			  result);
-		goto create_delsock;
-	}
-
-	/* Init con struct */
-	sock->sk->sk_user_data = &sctp_con;
-	sctp_con.sock = sock;
-	sctp_con.sock->sk->sk_data_ready = lowcomms_data_ready;
-
-	/* Bind to all interfaces. */
-	for (i = 0; i < dlm_local_count; i++) {
-		memcpy(&localaddr, dlm_local_addr[i], sizeof(localaddr));
-		make_sockaddr(&localaddr, dlm_config.tcp_port, &addr_len);
-
-		result = add_bind_addr(&localaddr, addr_len, num);
-		if (result)
-			goto create_delsock;
-		++num;
-	}
-
-	result = sock->ops->listen(sock, 5);
-	if (result < 0) {
-		log_print("Can't set socket listening");
-		goto create_delsock;
-	}
-
-	return 0;
-
- create_delsock:
-	sock_release(sock);
-	sctp_con.sock = NULL;
- out:
-	return result;
-}
-
-
-static struct writequeue_entry *new_writequeue_entry(int 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;
-
-	return entry;
-}
-
-void *dlm_lowcomms_get_buffer(int nodeid, int len, int allocation, char **ppc)
-{
-	struct writequeue_entry *e;
-	int offset = 0;
-	int users = 0;
-	struct nodeinfo *ni;
-
-	if (!atomic_read(&accepting))
-		return NULL;
-
-	ni = nodeid2nodeinfo(nodeid, allocation);
-	if (!ni)
-		return NULL;
-
-	spin_lock(&ni->writequeue_lock);
-	e = list_entry(ni->writequeue.prev, struct writequeue_entry, list);
-	if (((struct list_head *) e == &ni->writequeue) ||
-	    (PAGE_CACHE_SIZE - e->end < len)) {
-		e = NULL;
-	} else {
-		offset = e->end;
-		e->end += len;
-		users = e->users++;
-	}
-	spin_unlock(&ni->writequeue_lock);
-
-	if (e) {
-	      got_one:
-		if (users == 0)
-			kmap(e->page);
-		*ppc = page_address(e->page) + offset;
-		return e;
-	}
-
-	e = new_writequeue_entry(allocation);
-	if (e) {
-		spin_lock(&ni->writequeue_lock);
-		offset = e->end;
-		e->end += len;
-		e->ni = ni;
-		users = e->users++;
-		list_add_tail(&e->list, &ni->writequeue);
-		spin_unlock(&ni->writequeue_lock);
-		goto got_one;
-	}
-	return NULL;
-}
-
-void dlm_lowcomms_commit_buffer(void *arg)
-{
-	struct writequeue_entry *e = (struct writequeue_entry *) arg;
-	int users;
-	struct nodeinfo *ni = e->ni;
-
-	if (!atomic_read(&accepting))
-		return;
-
-	spin_lock(&ni->writequeue_lock);
-	users = --e->users;
-	if (users)
-		goto out;
-	e->len = e->end - e->offset;
-	kunmap(e->page);
-	spin_unlock(&ni->writequeue_lock);
-
-	if (!test_and_set_bit(NI_WRITE_PENDING, &ni->flags)) {
-		spin_lock_bh(&write_nodes_lock);
-		list_add_tail(&ni->write_list, &write_nodes);
-		spin_unlock_bh(&write_nodes_lock);
-		wake_up_process(send_task);
-	}
-	return;
-
-      out:
-	spin_unlock(&ni->writequeue_lock);
-	return;
-}
-
-static void free_entry(struct writequeue_entry *e)
-{
-	__free_page(e->page);
-	kfree(e);
-}
-
-/* Initiate an SCTP association. In theory we could just use sendmsg() on
-   the first IP address and it should work, but this allows us to set up the
-   association before sending any valuable data that we can't afford to lose.
-   It also keeps the send path clean as it can now always use the association ID */
-static void initiate_association(int nodeid)
-{
-	struct sockaddr_storage rem_addr;
-	static char outcmsg[CMSG_SPACE(sizeof(struct sctp_sndrcvinfo))];
-	struct msghdr outmessage;
-	struct cmsghdr *cmsg;
-	struct sctp_sndrcvinfo *sinfo;
-	int ret;
-	int addrlen;
-	char buf[1];
-	struct kvec iov[1];
-	struct nodeinfo *ni;
-
-	log_print("Initiating association with node %d", nodeid);
-
-	ni = nodeid2nodeinfo(nodeid, GFP_KERNEL);
-	if (!ni)
-		return;
-
-	if (nodeid_to_addr(nodeid, (struct sockaddr *)&rem_addr)) {
-		log_print("no address for nodeid %d", nodeid);
-		return;
-	}
-
-	make_sockaddr(&rem_addr, dlm_config.tcp_port, &addrlen);
-
-	outmessage.msg_name = &rem_addr;
-	outmessage.msg_namelen = addrlen;
-	outmessage.msg_control = outcmsg;
-	outmessage.msg_controllen = sizeof(outcmsg);
-	outmessage.msg_flags = MSG_EOR;
-
-	iov[0].iov_base = buf;
-	iov[0].iov_len = 1;
-
-	/* Real INIT messages seem to cause trouble. Just send a 1 byte message
-	   we can afford to lose */
-	cmsg = CMSG_FIRSTHDR(&outmessage);
-	cmsg->cmsg_level = IPPROTO_SCTP;
-	cmsg->cmsg_type = SCTP_SNDRCV;
-	cmsg->cmsg_len = CMSG_LEN(sizeof(struct sctp_sndrcvinfo));
-	sinfo = (struct sctp_sndrcvinfo *)CMSG_DATA(cmsg);
-	memset(sinfo, 0x00, sizeof(struct sctp_sndrcvinfo));
-	sinfo->sinfo_ppid = cpu_to_le32(dlm_local_nodeid);
-
-	outmessage.msg_controllen = cmsg->cmsg_len;
-	ret = kernel_sendmsg(sctp_con.sock, &outmessage, iov, 1, 1);
-	if (ret < 0) {
-		log_print("send INIT to node failed: %d", ret);
-		/* Try again later */
-		clear_bit(NI_INIT_PENDING, &ni->flags);
-	}
-}
-
-/* Send a message */
-static int send_to_sock(struct nodeinfo *ni)
-{
-	int ret = 0;
-	struct writequeue_entry *e;
-	int len, offset;
-	struct msghdr outmsg;
-	static char outcmsg[CMSG_SPACE(sizeof(struct sctp_sndrcvinfo))];
-	struct cmsghdr *cmsg;
-	struct sctp_sndrcvinfo *sinfo;
-	struct kvec iov;
-
-        /* See if we need to init an association before we start
-	   sending precious messages */
-	spin_lock(&ni->lock);
-	if (!ni->assoc_id && !test_and_set_bit(NI_INIT_PENDING, &ni->flags)) {
-		spin_unlock(&ni->lock);
-		initiate_association(ni->nodeid);
-		return 0;
-	}
-	spin_unlock(&ni->lock);
-
-	outmsg.msg_name = NULL; /* We use assoc_id */
-	outmsg.msg_namelen = 0;
-	outmsg.msg_control = outcmsg;
-	outmsg.msg_controllen = sizeof(outcmsg);
-	outmsg.msg_flags = MSG_DONTWAIT | MSG_NOSIGNAL | MSG_EOR;
-
-	cmsg = CMSG_FIRSTHDR(&outmsg);
-	cmsg->cmsg_level = IPPROTO_SCTP;
-	cmsg->cmsg_type = SCTP_SNDRCV;
-	cmsg->cmsg_len = CMSG_LEN(sizeof(struct sctp_sndrcvinfo));
-	sinfo = (struct sctp_sndrcvinfo *)CMSG_DATA(cmsg);
-	memset(sinfo, 0x00, sizeof(struct sctp_sndrcvinfo));
-	sinfo->sinfo_ppid = cpu_to_le32(dlm_local_nodeid);
-	sinfo->sinfo_assoc_id = ni->assoc_id;
-	outmsg.msg_controllen = cmsg->cmsg_len;
-
-	spin_lock(&ni->writequeue_lock);
-	for (;;) {
-		if (list_empty(&ni->writequeue))
-			break;
-		e = list_entry(ni->writequeue.next, struct writequeue_entry,
-			       list);
-		len = e->len;
-		offset = e->offset;
-		BUG_ON(len == 0 && e->users == 0);
-		spin_unlock(&ni->writequeue_lock);
-		kmap(e->page);
-
-		ret = 0;
-		if (len) {
-			iov.iov_base = page_address(e->page)+offset;
-			iov.iov_len = len;
-
-			ret = kernel_sendmsg(sctp_con.sock, &outmsg, &iov, 1,
-					     len);
-			if (ret == -EAGAIN) {
-				sctp_con.eagain_flag = 1;
-				goto out;
-			} else if (ret < 0)
-				goto send_error;
-		} else {
-			/* Don't starve people filling buffers */
-			schedule();
-		}
-
-		spin_lock(&ni->writequeue_lock);
-		e->offset += ret;
-		e->len -= ret;
-
-		if (e->len == 0 && e->users == 0) {
-			list_del(&e->list);
-			free_entry(e);
-			continue;
-		}
-	}
-	spin_unlock(&ni->writequeue_lock);
- out:
-	return ret;
-
- send_error:
-	log_print("Error sending to node %d %d", ni->nodeid, ret);
-	spin_lock(&ni->lock);
-	if (!test_and_set_bit(NI_INIT_PENDING, &ni->flags)) {
-		ni->assoc_id = 0;
-		spin_unlock(&ni->lock);
-		initiate_association(ni->nodeid);
-	} else
-		spin_unlock(&ni->lock);
-
-	return ret;
-}
-
-/* Try to send any messages that are pending */
-static void process_output_queue(void)
-{
-	struct list_head *list;
-	struct list_head *temp;
-
-	spin_lock_bh(&write_nodes_lock);
-	list_for_each_safe(list, temp, &write_nodes) {
-		struct nodeinfo *ni =
-		    list_entry(list, struct nodeinfo, write_list);
-		clear_bit(NI_WRITE_PENDING, &ni->flags);
-		list_del(&ni->write_list);
-
-		spin_unlock_bh(&write_nodes_lock);
-
-		send_to_sock(ni);
-		spin_lock_bh(&write_nodes_lock);
-	}
-	spin_unlock_bh(&write_nodes_lock);
-}
-
-/* Called after we've had -EAGAIN and been woken up */
-static void refill_write_queue(void)
-{
-	int i;
-
-	for (i=1; i<=max_nodeid; i++) {
-		struct nodeinfo *ni = nodeid2nodeinfo(i, 0);
-
-		if (ni) {
-			if (!test_and_set_bit(NI_WRITE_PENDING, &ni->flags)) {
-				spin_lock_bh(&write_nodes_lock);
-				list_add_tail(&ni->write_list, &write_nodes);
-				spin_unlock_bh(&write_nodes_lock);
-			}
-		}
-	}
-}
-
-static void clean_one_writequeue(struct nodeinfo *ni)
-{
-	struct list_head *list;
-	struct list_head *temp;
-
-	spin_lock(&ni->writequeue_lock);
-	list_for_each_safe(list, temp, &ni->writequeue) {
-		struct writequeue_entry *e =
-			list_entry(list, struct writequeue_entry, list);
-		list_del(&e->list);
-		free_entry(e);
-	}
-	spin_unlock(&ni->writequeue_lock);
-}
-
-static void clean_writequeues(void)
-{
-	int i;
-
-	for (i=1; i<=max_nodeid; i++) {
-		struct nodeinfo *ni = nodeid2nodeinfo(i, 0);
-		if (ni)
-			clean_one_writequeue(ni);
-	}
-}
-
-
-static void dealloc_nodeinfo(void)
-{
-	int i;
-
-	for (i=1; i<=max_nodeid; i++) {
-		struct nodeinfo *ni = nodeid2nodeinfo(i, 0);
-		if (ni) {
-			idr_remove(&nodeinfo_idr, i);
-			kfree(ni);
-		}
-	}
-}
-
-int dlm_lowcomms_close(int nodeid)
-{
-	struct nodeinfo *ni;
-
-	ni = nodeid2nodeinfo(nodeid, 0);
-	if (!ni)
-		return -1;
-
-	spin_lock(&ni->lock);
-	if (ni->assoc_id) {
-		ni->assoc_id = 0;
-		/* Don't send shutdown here, sctp will just queue it
-		   till the node comes back up! */
-	}
-	spin_unlock(&ni->lock);
-
-	clean_one_writequeue(ni);
-	clear_bit(NI_INIT_PENDING, &ni->flags);
-	return 0;
-}
-
-static int write_list_empty(void)
-{
-	int status;
-
-	spin_lock_bh(&write_nodes_lock);
-	status = list_empty(&write_nodes);
-	spin_unlock_bh(&write_nodes_lock);
-
-	return status;
-}
-
-static int dlm_recvd(void *data)
-{
-	DECLARE_WAITQUEUE(wait, current);
-
-	while (!kthread_should_stop()) {
-		int count = 0;
-
-		set_current_state(TASK_INTERRUPTIBLE);
-		add_wait_queue(&lowcomms_recv_wait, &wait);
-		if (!test_bit(CF_READ_PENDING, &sctp_con.flags))
-			schedule();
-		remove_wait_queue(&lowcomms_recv_wait, &wait);
-		set_current_state(TASK_RUNNING);
-
-		if (test_and_clear_bit(CF_READ_PENDING, &sctp_con.flags)) {
-			int ret;
-
-			do {
-				ret = receive_from_sock();
-
-				/* Don't starve out everyone else */
-				if (++count >= MAX_RX_MSG_COUNT) {
-					schedule();
-					count = 0;
-				}
-			} while (!kthread_should_stop() && ret >=0);
-		}
-		schedule();
-	}
-
-	return 0;
-}
-
-static int dlm_sendd(void *data)
-{
-	DECLARE_WAITQUEUE(wait, current);
-
-	add_wait_queue(sctp_con.sock->sk->sk_sleep, &wait);
-
-	while (!kthread_should_stop()) {
-		set_current_state(TASK_INTERRUPTIBLE);
-		if (write_list_empty())
-			schedule();
-		set_current_state(TASK_RUNNING);
-
-		if (sctp_con.eagain_flag) {
-			sctp_con.eagain_flag = 0;
-			refill_write_queue();
-		}
-		process_output_queue();
-	}
-
-	remove_wait_queue(sctp_con.sock->sk->sk_sleep, &wait);
-
-	return 0;
-}
-
-static void daemons_stop(void)
-{
-	kthread_stop(recv_task);
-	kthread_stop(send_task);
-}
-
-static int daemons_start(void)
-{
-	struct task_struct *p;
-	int error;
-
-	p = kthread_run(dlm_recvd, NULL, "dlm_recvd");
-	error = IS_ERR(p);
-       	if (error) {
-		log_print("can't start dlm_recvd %d", error);
-		return error;
-	}
-	recv_task = p;
-
-	p = kthread_run(dlm_sendd, NULL, "dlm_sendd");
-	error = IS_ERR(p);
-       	if (error) {
-		log_print("can't start dlm_sendd %d", error);
-		kthread_stop(recv_task);
-		return error;
-	}
-	send_task = p;
-
-	return 0;
-}
-
-/*
- * This is quite likely to sleep...
- */
-int dlm_lowcomms_start(void)
-{
-	int error;
-
-	error = init_sock();
-	if (error)
-		goto fail_sock;
-	error = daemons_start();
-	if (error)
-		goto fail_sock;
-	atomic_set(&accepting, 1);
-	return 0;
-
- fail_sock:
-	close_connection();
-	return error;
-}
-
-/* Set all the activity flags to prevent any socket activity. */
-
-void dlm_lowcomms_stop(void)
-{
-	atomic_set(&accepting, 0);
-	sctp_con.flags = 0x7;
-	daemons_stop();
-	clean_writequeues();
-	close_connection();
-	dealloc_nodeinfo();
-	max_nodeid = 0;
-}
-
-int dlm_lowcomms_init(void)
-{
-	init_waitqueue_head(&lowcomms_recv_wait);
-	spin_lock_init(&write_nodes_lock);
-	INIT_LIST_HEAD(&write_nodes);
-	init_rwsem(&nodeinfo_lock);
-	return 0;
-}
-
-void dlm_lowcomms_exit(void)
-{
-	int i;
-
-	for (i = 0; i < dlm_local_count; i++)
-		kfree(dlm_local_addr[i]);
-	dlm_local_count = 0;
-	dlm_local_nodeid = 0;
-}
-