staging: zcache: rename ramster to zcache

[V2: no code changes, patchset now generated via git format-patch -M]

In staging, rename ramster to zcache

The original zcache in staging was a "demo" version, and this new zcache
is a significant rewrite.  While certain disagreements were being resolved,
both "old zcache" and "new zcache" needed to reside in the staging tree
simultaneously.  In order to minimize code change and churn, the newer
version of zcache was temporarily merged into the "ramster" staging driver
which, prior to that, had at one time heavily leveraged the older version
of zcache.  So, recently, "new zcache" resided in the ramster directory.

Got that? No? Sorry, temporary political compromises are rarely pretty.

The older version of zcache is no longer being maintained and has now
been removed from the staging tree.  So now the newer version of zcache
can rightfully reclaim sole possession of the name "zcache".

FYI, this [PATCH 2/5] is simply a "git mv" generated by "git format-patch -M".

Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 2253 insertions, 0 deletions

diff --git a/drivers/staging/zcache/ramster/tcp.c b/drivers/staging/zcache/ramster/tcp.c
new file mode 100644
index 0000000..aa2a1a7
--- /dev/null
+++ b/drivers/staging/zcache/ramster/tcp.c
@@ -0,0 +1,2253 @@
+/* -*- mode: c; c-basic-offset: 8; -*-
+ *
+ * vim: noexpandtab sw=8 ts=8 sts=0:
+ *
+ * Copyright (C) 2004 Oracle.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ *
+ * ----
+ *
+ * Callers for this were originally written against a very simple synchronus
+ * API.  This implementation reflects those simple callers.  Some day I'm sure
+ * we'll need to move to a more robust posting/callback mechanism.
+ *
+ * Transmit calls pass in kernel virtual addresses and block copying this into
+ * the socket's tx buffers via a usual blocking sendmsg.  They'll block waiting
+ * for a failed socket to timeout.  TX callers can also pass in a poniter to an
+ * 'int' which gets filled with an errno off the wire in response to the
+ * message they send.
+ *
+ * Handlers for unsolicited messages are registered.  Each socket has a page
+ * that incoming data is copied into.  First the header, then the data.
+ * Handlers are called from only one thread with a reference to this per-socket
+ * page.  This page is destroyed after the handler call, so it can't be
+ * referenced beyond the call.  Handlers may block but are discouraged from
+ * doing so.
+ *
+ * Any framing errors (bad magic, large payload lengths) close a connection.
+ *
+ * Our sock_container holds the state we associate with a socket.  It's current
+ * framing state is held there as well as the refcounting we do around when it
+ * is safe to tear down the socket.  The socket is only finally torn down from
+ * the container when the container loses all of its references -- so as long
+ * as you hold a ref on the container you can trust that the socket is valid
+ * for use with kernel socket APIs.
+ *
+ * Connections are initiated between a pair of nodes when the node with the
+ * higher node number gets a heartbeat callback which indicates that the lower
+ * numbered node has started heartbeating.  The lower numbered node is passive
+ * and only accepts the connection if the higher numbered node is heartbeating.
+ */
+
+#include <linux/kernel.h>
+#include <linux/jiffies.h>
+#include <linux/slab.h>
+#include <linux/idr.h>
+#include <linux/kref.h>
+#include <linux/net.h>
+#include <linux/export.h>
+#include <linux/uaccess.h>
+#include <net/tcp.h>
+
+
+#include "heartbeat.h"
+#include "tcp.h"
+#include "nodemanager.h"
+#define MLOG_MASK_PREFIX ML_TCP
+#include "masklog.h"
+
+#include "tcp_internal.h"
+
+#define SC_NODEF_FMT "node %s (num %u) at %pI4:%u"
+
+/*
+ * In the following two log macros, the whitespace after the ',' just
+ * before ##args is intentional. Otherwise, gcc 2.95 will eat the
+ * previous token if args expands to nothing.
+ */
+#define msglog(hdr, fmt, args...) do {					\
+	typeof(hdr) __hdr = (hdr);					\
+	mlog(ML_MSG, "[mag %u len %u typ %u stat %d sys_stat %d "	\
+	     "key %08x num %u] " fmt,					\
+	be16_to_cpu(__hdr->magic), be16_to_cpu(__hdr->data_len),	\
+	     be16_to_cpu(__hdr->msg_type), be32_to_cpu(__hdr->status),	\
+	     be32_to_cpu(__hdr->sys_status), be32_to_cpu(__hdr->key),	\
+	     be32_to_cpu(__hdr->msg_num) ,  ##args);			\
+} while (0)
+
+#define sclog(sc, fmt, args...) do {					\
+	typeof(sc) __sc = (sc);						\
+	mlog(ML_SOCKET, "[sc %p refs %d sock %p node %u page %p "	\
+	     "pg_off %zu] " fmt, __sc,					\
+	     atomic_read(&__sc->sc_kref.refcount), __sc->sc_sock,	\
+	    __sc->sc_node->nd_num, __sc->sc_page, __sc->sc_page_off ,	\
+	    ##args);							\
+} while (0)
+
+static DEFINE_RWLOCK(r2net_handler_lock);
+static struct rb_root r2net_handler_tree = RB_ROOT;
+
+static struct r2net_node r2net_nodes[R2NM_MAX_NODES];
+
+/* XXX someday we'll need better accounting */
+static struct socket *r2net_listen_sock;
+
+/*
+ * listen work is only queued by the listening socket callbacks on the
+ * r2net_wq.  teardown detaches the callbacks before destroying the workqueue.
+ * quorum work is queued as sock containers are shutdown.. stop_listening
+ * tears down all the node's sock containers, preventing future shutdowns
+ * and queued quorum work, before canceling delayed quorum work and
+ * destroying the work queue.
+ */
+static struct workqueue_struct *r2net_wq;
+static struct work_struct r2net_listen_work;
+
+static struct r2hb_callback_func r2net_hb_up, r2net_hb_down;
+#define R2NET_HB_PRI 0x1
+
+static struct r2net_handshake *r2net_hand;
+static struct r2net_msg *r2net_keep_req, *r2net_keep_resp;
+
+static int r2net_sys_err_translations[R2NET_ERR_MAX] = {
+		[R2NET_ERR_NONE]	= 0,
+		[R2NET_ERR_NO_HNDLR]	= -ENOPROTOOPT,
+		[R2NET_ERR_OVERFLOW]	= -EOVERFLOW,
+		[R2NET_ERR_DIED]	= -EHOSTDOWN,};
+
+/* can't quite avoid *all* internal declarations :/ */
+static void r2net_sc_connect_completed(struct work_struct *work);
+static void r2net_rx_until_empty(struct work_struct *work);
+static void r2net_shutdown_sc(struct work_struct *work);
+static void r2net_listen_data_ready(struct sock *sk, int bytes);
+static void r2net_sc_send_keep_req(struct work_struct *work);
+static void r2net_idle_timer(unsigned long data);
+static void r2net_sc_postpone_idle(struct r2net_sock_container *sc);
+static void r2net_sc_reset_idle_timer(struct r2net_sock_container *sc);
+
+#ifdef CONFIG_DEBUG_FS
+static void r2net_init_nst(struct r2net_send_tracking *nst, u32 msgtype,
+			   u32 msgkey, struct task_struct *task, u8 node)
+{
+	INIT_LIST_HEAD(&nst->st_net_debug_item);
+	nst->st_task = task;
+	nst->st_msg_type = msgtype;
+	nst->st_msg_key = msgkey;
+	nst->st_node = node;
+}
+
+static inline void r2net_set_nst_sock_time(struct r2net_send_tracking *nst)
+{
+	nst->st_sock_time = ktime_get();
+}
+
+static inline void r2net_set_nst_send_time(struct r2net_send_tracking *nst)
+{
+	nst->st_send_time = ktime_get();
+}
+
+static inline void r2net_set_nst_status_time(struct r2net_send_tracking *nst)
+{
+	nst->st_status_time = ktime_get();
+}
+
+static inline void r2net_set_nst_sock_container(struct r2net_send_tracking *nst,
+						struct r2net_sock_container *sc)
+{
+	nst->st_sc = sc;
+}
+
+static inline void r2net_set_nst_msg_id(struct r2net_send_tracking *nst,
+					u32 msg_id)
+{
+	nst->st_id = msg_id;
+}
+
+static inline void r2net_set_sock_timer(struct r2net_sock_container *sc)
+{
+	sc->sc_tv_timer = ktime_get();
+}
+
+static inline void r2net_set_data_ready_time(struct r2net_sock_container *sc)
+{
+	sc->sc_tv_data_ready = ktime_get();
+}
+
+static inline void r2net_set_advance_start_time(struct r2net_sock_container *sc)
+{
+	sc->sc_tv_advance_start = ktime_get();
+}
+
+static inline void r2net_set_advance_stop_time(struct r2net_sock_container *sc)
+{
+	sc->sc_tv_advance_stop = ktime_get();
+}
+
+static inline void r2net_set_func_start_time(struct r2net_sock_container *sc)
+{
+	sc->sc_tv_func_start = ktime_get();
+}
+
+static inline void r2net_set_func_stop_time(struct r2net_sock_container *sc)
+{
+	sc->sc_tv_func_stop = ktime_get();
+}
+
+#else  /* CONFIG_DEBUG_FS */
+# define r2net_init_nst(a, b, c, d, e)
+# define r2net_set_nst_sock_time(a)
+# define r2net_set_nst_send_time(a)
+# define r2net_set_nst_status_time(a)
+# define r2net_set_nst_sock_container(a, b)
+# define r2net_set_nst_msg_id(a, b)
+# define r2net_set_sock_timer(a)
+# define r2net_set_data_ready_time(a)
+# define r2net_set_advance_start_time(a)
+# define r2net_set_advance_stop_time(a)
+# define r2net_set_func_start_time(a)
+# define r2net_set_func_stop_time(a)
+#endif /* CONFIG_DEBUG_FS */
+
+#ifdef CONFIG_RAMSTER_FS_STATS
+static ktime_t r2net_get_func_run_time(struct r2net_sock_container *sc)
+{
+	return ktime_sub(sc->sc_tv_func_stop, sc->sc_tv_func_start);
+}
+
+static void r2net_update_send_stats(struct r2net_send_tracking *nst,
+				    struct r2net_sock_container *sc)
+{
+	sc->sc_tv_status_total = ktime_add(sc->sc_tv_status_total,
+					   ktime_sub(ktime_get(),
+						     nst->st_status_time));
+	sc->sc_tv_send_total = ktime_add(sc->sc_tv_send_total,
+					 ktime_sub(nst->st_status_time,
+						   nst->st_send_time));
+	sc->sc_tv_acquiry_total = ktime_add(sc->sc_tv_acquiry_total,
+					    ktime_sub(nst->st_send_time,
+						      nst->st_sock_time));
+	sc->sc_send_count++;
+}
+
+static void r2net_update_recv_stats(struct r2net_sock_container *sc)
+{
+	sc->sc_tv_process_total = ktime_add(sc->sc_tv_process_total,
+					    r2net_get_func_run_time(sc));
+	sc->sc_recv_count++;
+}
+
+#else
+
+# define r2net_update_send_stats(a, b)
+
+# define r2net_update_recv_stats(sc)
+
+#endif /* CONFIG_RAMSTER_FS_STATS */
+
+static inline int r2net_reconnect_delay(void)
+{
+	return r2nm_single_cluster->cl_reconnect_delay_ms;
+}
+
+static inline int r2net_keepalive_delay(void)
+{
+	return r2nm_single_cluster->cl_keepalive_delay_ms;
+}
+
+static inline int r2net_idle_timeout(void)
+{
+	return r2nm_single_cluster->cl_idle_timeout_ms;
+}
+
+static inline int r2net_sys_err_to_errno(enum r2net_system_error err)
+{
+	int trans;
+	BUG_ON(err >= R2NET_ERR_MAX);
+	trans = r2net_sys_err_translations[err];
+
+	/* Just in case we mess up the translation table above */
+	BUG_ON(err != R2NET_ERR_NONE && trans == 0);
+	return trans;
+}
+
+struct r2net_node *r2net_nn_from_num(u8 node_num)
+{
+	BUG_ON(node_num >= ARRAY_SIZE(r2net_nodes));
+	return &r2net_nodes[node_num];
+}
+
+static u8 r2net_num_from_nn(struct r2net_node *nn)
+{
+	BUG_ON(nn == NULL);
+	return nn - r2net_nodes;
+}
+
+/* ------------------------------------------------------------ */
+
+static int r2net_prep_nsw(struct r2net_node *nn, struct r2net_status_wait *nsw)
+{
+	int ret = 0;
+
+	do {
+		if (!idr_pre_get(&nn->nn_status_idr, GFP_ATOMIC)) {
+			ret = -EAGAIN;
+			break;
+		}
+		spin_lock(&nn->nn_lock);
+		ret = idr_get_new(&nn->nn_status_idr, nsw, &nsw->ns_id);
+		if (ret == 0)
+			list_add_tail(&nsw->ns_node_item,
+				      &nn->nn_status_list);
+		spin_unlock(&nn->nn_lock);
+	} while (ret == -EAGAIN);
+
+	if (ret == 0)  {
+		init_waitqueue_head(&nsw->ns_wq);
+		nsw->ns_sys_status = R2NET_ERR_NONE;
+		nsw->ns_status = 0;
+	}
+
+	return ret;
+}
+
+static void r2net_complete_nsw_locked(struct r2net_node *nn,
+				      struct r2net_status_wait *nsw,
+				      enum r2net_system_error sys_status,
+				      s32 status)
+{
+	assert_spin_locked(&nn->nn_lock);
+
+	if (!list_empty(&nsw->ns_node_item)) {
+		list_del_init(&nsw->ns_node_item);
+		nsw->ns_sys_status = sys_status;
+		nsw->ns_status = status;
+		idr_remove(&nn->nn_status_idr, nsw->ns_id);
+		wake_up(&nsw->ns_wq);
+	}
+}
+
+static void r2net_complete_nsw(struct r2net_node *nn,
+			       struct r2net_status_wait *nsw,
+			       u64 id, enum r2net_system_error sys_status,
+			       s32 status)
+{
+	spin_lock(&nn->nn_lock);
+	if (nsw == NULL) {
+		if (id > INT_MAX)
+			goto out;
+
+		nsw = idr_find(&nn->nn_status_idr, id);
+		if (nsw == NULL)
+			goto out;
+	}
+
+	r2net_complete_nsw_locked(nn, nsw, sys_status, status);
+
+out:
+	spin_unlock(&nn->nn_lock);
+	return;
+}
+
+static void r2net_complete_nodes_nsw(struct r2net_node *nn)
+{
+	struct r2net_status_wait *nsw, *tmp;
+	unsigned int num_kills = 0;
+
+	assert_spin_locked(&nn->nn_lock);
+
+	list_for_each_entry_safe(nsw, tmp, &nn->nn_status_list, ns_node_item) {
+		r2net_complete_nsw_locked(nn, nsw, R2NET_ERR_DIED, 0);
+		num_kills++;
+	}
+
+	mlog(0, "completed %d messages for node %u\n", num_kills,
+	     r2net_num_from_nn(nn));
+}
+
+static int r2net_nsw_completed(struct r2net_node *nn,
+			       struct r2net_status_wait *nsw)
+{
+	int completed;
+	spin_lock(&nn->nn_lock);
+	completed = list_empty(&nsw->ns_node_item);
+	spin_unlock(&nn->nn_lock);
+	return completed;
+}
+
+/* ------------------------------------------------------------ */
+
+static void sc_kref_release(struct kref *kref)
+{
+	struct r2net_sock_container *sc = container_of(kref,
+					struct r2net_sock_container, sc_kref);
+	BUG_ON(timer_pending(&sc->sc_idle_timeout));
+
+	sclog(sc, "releasing\n");
+
+	if (sc->sc_sock) {
+		sock_release(sc->sc_sock);
+		sc->sc_sock = NULL;
+	}
+
+	r2nm_undepend_item(&sc->sc_node->nd_item);
+	r2nm_node_put(sc->sc_node);
+	sc->sc_node = NULL;
+
+	r2net_debug_del_sc(sc);
+	kfree(sc);
+}
+
+static void sc_put(struct r2net_sock_container *sc)
+{
+	sclog(sc, "put\n");
+	kref_put(&sc->sc_kref, sc_kref_release);
+}
+static void sc_get(struct r2net_sock_container *sc)
+{
+	sclog(sc, "get\n");
+	kref_get(&sc->sc_kref);
+}
+static struct r2net_sock_container *sc_alloc(struct r2nm_node *node)
+{
+	struct r2net_sock_container *sc, *ret = NULL;
+	struct page *page = NULL;
+	int status = 0;
+
+	page = alloc_page(GFP_NOFS);
+	sc = kzalloc(sizeof(*sc), GFP_NOFS);
+	if (sc == NULL || page == NULL)
+		goto out;
+
+	kref_init(&sc->sc_kref);
+	r2nm_node_get(node);
+	sc->sc_node = node;
+
+	/* pin the node item of the remote node */
+	status = r2nm_depend_item(&node->nd_item);
+	if (status) {
+		mlog_errno(status);
+		r2nm_node_put(node);
+		goto out;
+	}
+	INIT_WORK(&sc->sc_connect_work, r2net_sc_connect_completed);
+	INIT_WORK(&sc->sc_rx_work, r2net_rx_until_empty);
+	INIT_WORK(&sc->sc_shutdown_work, r2net_shutdown_sc);
+	INIT_DELAYED_WORK(&sc->sc_keepalive_work, r2net_sc_send_keep_req);
+
+	init_timer(&sc->sc_idle_timeout);
+	sc->sc_idle_timeout.function = r2net_idle_timer;
+	sc->sc_idle_timeout.data = (unsigned long)sc;
+
+	sclog(sc, "alloced\n");
+
+	ret = sc;
+	sc->sc_page = page;
+	r2net_debug_add_sc(sc);
+	sc = NULL;
+	page = NULL;
+
+out:
+	if (page)
+		__free_page(page);
+	kfree(sc);
+
+	return ret;
+}
+
+/* ------------------------------------------------------------ */
+
+static void r2net_sc_queue_work(struct r2net_sock_container *sc,
+				struct work_struct *work)
+{
+	sc_get(sc);
+	if (!queue_work(r2net_wq, work))
+		sc_put(sc);
+}
+static void r2net_sc_queue_delayed_work(struct r2net_sock_container *sc,
+					struct delayed_work *work,
+					int delay)
+{
+	sc_get(sc);
+	if (!queue_delayed_work(r2net_wq, work, delay))
+		sc_put(sc);
+}
+static void r2net_sc_cancel_delayed_work(struct r2net_sock_container *sc,
+					 struct delayed_work *work)
+{
+	if (cancel_delayed_work(work))
+		sc_put(sc);
+}
+
+static atomic_t r2net_connected_peers = ATOMIC_INIT(0);
+
+int r2net_num_connected_peers(void)
+{
+	return atomic_read(&r2net_connected_peers);
+}
+
+static void r2net_set_nn_state(struct r2net_node *nn,
+			       struct r2net_sock_container *sc,
+			       unsigned valid, int err)
+{
+	int was_valid = nn->nn_sc_valid;
+	int was_err = nn->nn_persistent_error;
+	struct r2net_sock_container *old_sc = nn->nn_sc;
+
+	assert_spin_locked(&nn->nn_lock);
+
+	if (old_sc && !sc)
+		atomic_dec(&r2net_connected_peers);
+	else if (!old_sc && sc)
+		atomic_inc(&r2net_connected_peers);
+
+	/* the node num comparison and single connect/accept path should stop
+	 * an non-null sc from being overwritten with another */
+	BUG_ON(sc && nn->nn_sc && nn->nn_sc != sc);
+	mlog_bug_on_msg(err && valid, "err %d valid %u\n", err, valid);
+	mlog_bug_on_msg(valid && !sc, "valid %u sc %p\n", valid, sc);
+
+	if (was_valid && !valid && err == 0)
+		err = -ENOTCONN;
+
+	mlog(ML_CONN, "node %u sc: %p -> %p, valid %u -> %u, err %d -> %d\n",
+	     r2net_num_from_nn(nn), nn->nn_sc, sc, nn->nn_sc_valid, valid,
+	     nn->nn_persistent_error, err);
+
+	nn->nn_sc = sc;
+	nn->nn_sc_valid = valid ? 1 : 0;
+	nn->nn_persistent_error = err;
+
+	/* mirrors r2net_tx_can_proceed() */
+	if (nn->nn_persistent_error || nn->nn_sc_valid)
+		wake_up(&nn->nn_sc_wq);
+
+	if (!was_err && nn->nn_persistent_error) {
+		queue_delayed_work(r2net_wq, &nn->nn_still_up,
+				   msecs_to_jiffies(R2NET_QUORUM_DELAY_MS));
+	}
+
+	if (was_valid && !valid) {
+		pr_notice("ramster: No longer connected to " SC_NODEF_FMT "\n",
+			old_sc->sc_node->nd_name, old_sc->sc_node->nd_num,
+			&old_sc->sc_node->nd_ipv4_address,
+			ntohs(old_sc->sc_node->nd_ipv4_port));
+		r2net_complete_nodes_nsw(nn);
+	}
+
+	if (!was_valid && valid) {
+		cancel_delayed_work(&nn->nn_connect_expired);
+		pr_notice("ramster: %s " SC_NODEF_FMT "\n",
+		       r2nm_this_node() > sc->sc_node->nd_num ?
+		       "Connected to" : "Accepted connection from",
+		       sc->sc_node->nd_name, sc->sc_node->nd_num,
+			&sc->sc_node->nd_ipv4_address,
+			ntohs(sc->sc_node->nd_ipv4_port));
+	}
+
+	/* trigger the connecting worker func as long as we're not valid,
+	 * it will back off if it shouldn't connect.  This can be called
+	 * from node config teardown and so needs to be careful about
+	 * the work queue actually being up. */
+	if (!valid && r2net_wq) {
+		unsigned long delay;
+		/* delay if we're within a RECONNECT_DELAY of the
+		 * last attempt */
+		delay = (nn->nn_last_connect_attempt +
+			 msecs_to_jiffies(r2net_reconnect_delay()))
+			- jiffies;
+		if (delay > msecs_to_jiffies(r2net_reconnect_delay()))
+			delay = 0;
+		mlog(ML_CONN, "queueing conn attempt in %lu jiffies\n", delay);
+		queue_delayed_work(r2net_wq, &nn->nn_connect_work, delay);
+
+		/*
+		 * Delay the expired work after idle timeout.
+		 *
+		 * We might have lots of failed connection attempts that run
+		 * through here but we only cancel the connect_expired work when
+		 * a connection attempt succeeds.  So only the first enqueue of
+		 * the connect_expired work will do anything.  The rest will see
+		 * that it's already queued and do nothing.
+		 */
+		delay += msecs_to_jiffies(r2net_idle_timeout());
+		queue_delayed_work(r2net_wq, &nn->nn_connect_expired, delay);
+	}
+
+	/* keep track of the nn's sc ref for the caller */
+	if ((old_sc == NULL) && sc)
+		sc_get(sc);
+	if (old_sc && (old_sc != sc)) {
+		r2net_sc_queue_work(old_sc, &old_sc->sc_shutdown_work);
+		sc_put(old_sc);
+	}
+}
+
+/* see r2net_register_callbacks() */
+static void r2net_data_ready(struct sock *sk, int bytes)
+{
+	void (*ready)(struct sock *sk, int bytes);
+
+	read_lock(&sk->sk_callback_lock);
+	if (sk->sk_user_data) {
+		struct r2net_sock_container *sc = sk->sk_user_data;
+		sclog(sc, "data_ready hit\n");
+		r2net_set_data_ready_time(sc);
+		r2net_sc_queue_work(sc, &sc->sc_rx_work);
+		ready = sc->sc_data_ready;
+	} else {
+		ready = sk->sk_data_ready;
+	}
+	read_unlock(&sk->sk_callback_lock);
+
+	ready(sk, bytes);
+}
+
+/* see r2net_register_callbacks() */
+static void r2net_state_change(struct sock *sk)
+{
+	void (*state_change)(struct sock *sk);
+	struct r2net_sock_container *sc;
+
+	read_lock(&sk->sk_callback_lock);
+	sc = sk->sk_user_data;
+	if (sc == NULL) {
+		state_change = sk->sk_state_change;
+		goto out;
+	}
+
+	sclog(sc, "state_change to %d\n", sk->sk_state);
+
+	state_change = sc->sc_state_change;
+
+	switch (sk->sk_state) {
+
+	/* ignore connecting sockets as they make progress */
+	case TCP_SYN_SENT:
+	case TCP_SYN_RECV:
+		break;
+	case TCP_ESTABLISHED:
+		r2net_sc_queue_work(sc, &sc->sc_connect_work);
+		break;
+	default:
+		pr_info("ramster: Connection to "
+			SC_NODEF_FMT " shutdown, state %d\n",
+			sc->sc_node->nd_name, sc->sc_node->nd_num,
+			&sc->sc_node->nd_ipv4_address,
+			ntohs(sc->sc_node->nd_ipv4_port), sk->sk_state);
+		r2net_sc_queue_work(sc, &sc->sc_shutdown_work);
+		break;
+
+	}
+out:
+	read_unlock(&sk->sk_callback_lock);
+	state_change(sk);
+}
+
+/*
+ * we register callbacks so we can queue work on events before calling
+ * the original callbacks.  our callbacks are careful to test user_data
+ * to discover when they've reaced with r2net_unregister_callbacks().
+ */
+static void r2net_register_callbacks(struct sock *sk,
+				     struct r2net_sock_container *sc)
+{
+	write_lock_bh(&sk->sk_callback_lock);
+
+	/* accepted sockets inherit the old listen socket data ready */
+	if (sk->sk_data_ready == r2net_listen_data_ready) {
+		sk->sk_data_ready = sk->sk_user_data;
+		sk->sk_user_data = NULL;
+	}
+
+	BUG_ON(sk->sk_user_data != NULL);
+	sk->sk_user_data = sc;
+	sc_get(sc);
+
+	sc->sc_data_ready = sk->sk_data_ready;
+	sc->sc_state_change = sk->sk_state_change;
+	sk->sk_data_ready = r2net_data_ready;
+	sk->sk_state_change = r2net_state_change;
+
+	mutex_init(&sc->sc_send_lock);
+
+	write_unlock_bh(&sk->sk_callback_lock);
+}
+
+static int r2net_unregister_callbacks(struct sock *sk,
+					struct r2net_sock_container *sc)
+{
+	int ret = 0;
+
+	write_lock_bh(&sk->sk_callback_lock);
+	if (sk->sk_user_data == sc) {
+		ret = 1;
+		sk->sk_user_data = NULL;
+		sk->sk_data_ready = sc->sc_data_ready;
+		sk->sk_state_change = sc->sc_state_change;
+	}
+	write_unlock_bh(&sk->sk_callback_lock);
+
+	return ret;
+}
+
+/*
+ * this is a little helper that is called by callers who have seen a problem
+ * with an sc and want to detach it from the nn if someone already hasn't beat
+ * them to it.  if an error is given then the shutdown will be persistent
+ * and pending transmits will be canceled.
+ */
+static void r2net_ensure_shutdown(struct r2net_node *nn,
+					struct r2net_sock_container *sc,
+				   int err)
+{
+	spin_lock(&nn->nn_lock);
+	if (nn->nn_sc == sc)
+		r2net_set_nn_state(nn, NULL, 0, err);
+	spin_unlock(&nn->nn_lock);
+}
+
+/*
+ * This work queue function performs the blocking parts of socket shutdown.  A
+ * few paths lead here.  set_nn_state will trigger this callback if it sees an
+ * sc detached from the nn.  state_change will also trigger this callback
+ * directly when it sees errors.  In that case we need to call set_nn_state
+ * ourselves as state_change couldn't get the nn_lock and call set_nn_state
+ * itself.
+ */
+static void r2net_shutdown_sc(struct work_struct *work)
+{
+	struct r2net_sock_container *sc =
+		container_of(work, struct r2net_sock_container,
+			     sc_shutdown_work);
+	struct r2net_node *nn = r2net_nn_from_num(sc->sc_node->nd_num);
+
+	sclog(sc, "shutting down\n");
+
+	/* drop the callbacks ref and call shutdown only once */
+	if (r2net_unregister_callbacks(sc->sc_sock->sk, sc)) {
+		/* we shouldn't flush as we're in the thread, the
+		 * races with pending sc work structs are harmless */
+		del_timer_sync(&sc->sc_idle_timeout);
+		r2net_sc_cancel_delayed_work(sc, &sc->sc_keepalive_work);
+		sc_put(sc);
+		kernel_sock_shutdown(sc->sc_sock, SHUT_RDWR);
+	}
+
+	/* not fatal so failed connects before the other guy has our
+	 * heartbeat can be retried */
+	r2net_ensure_shutdown(nn, sc, 0);
+	sc_put(sc);
+}
+
+/* ------------------------------------------------------------ */
+
+static int r2net_handler_cmp(struct r2net_msg_handler *nmh, u32 msg_type,
+			     u32 key)
+{
+	int ret = memcmp(&nmh->nh_key, &key, sizeof(key));
+
+	if (ret == 0)
+		ret = memcmp(&nmh->nh_msg_type, &msg_type, sizeof(msg_type));
+
+	return ret;
+}
+
+static struct r2net_msg_handler *
+r2net_handler_tree_lookup(u32 msg_type, u32 key, struct rb_node ***ret_p,
+				struct rb_node **ret_parent)
+{
+	struct rb_node **p = &r2net_handler_tree.rb_node;
+	struct rb_node *parent = NULL;
+	struct r2net_msg_handler *nmh, *ret = NULL;
+	int cmp;
+
+	while (*p) {
+		parent = *p;
+		nmh = rb_entry(parent, struct r2net_msg_handler, nh_node);
+		cmp = r2net_handler_cmp(nmh, msg_type, key);
+
+		if (cmp < 0)
+			p = &(*p)->rb_left;
+		else if (cmp > 0)
+			p = &(*p)->rb_right;
+		else {
+			ret = nmh;
+			break;
+		}
+	}
+
+	if (ret_p != NULL)
+		*ret_p = p;
+	if (ret_parent != NULL)
+		*ret_parent = parent;
+
+	return ret;
+}
+
+static void r2net_handler_kref_release(struct kref *kref)
+{
+	struct r2net_msg_handler *nmh;
+	nmh = container_of(kref, struct r2net_msg_handler, nh_kref);
+
+	kfree(nmh);
+}
+
+static void r2net_handler_put(struct r2net_msg_handler *nmh)
+{
+	kref_put(&nmh->nh_kref, r2net_handler_kref_release);
+}
+
+/* max_len is protection for the handler func.  incoming messages won't
+ * be given to the handler if their payload is longer than the max. */
+int r2net_register_handler(u32 msg_type, u32 key, u32 max_len,
+			   r2net_msg_handler_func *func, void *data,
+			   r2net_post_msg_handler_func *post_func,
+			   struct list_head *unreg_list)
+{
+	struct r2net_msg_handler *nmh = NULL;
+	struct rb_node **p, *parent;
+	int ret = 0;
+
+	if (max_len > R2NET_MAX_PAYLOAD_BYTES) {
+		mlog(0, "max_len for message handler out of range: %u\n",
+			max_len);
+		ret = -EINVAL;
+		goto out;
+	}
+
+	if (!msg_type) {
+		mlog(0, "no message type provided: %u, %p\n", msg_type, func);
+		ret = -EINVAL;
+		goto out;
+
+	}
+	if (!func) {
+		mlog(0, "no message handler provided: %u, %p\n",
+		       msg_type, func);
+		ret = -EINVAL;
+		goto out;
+	}
+
+	nmh = kzalloc(sizeof(struct r2net_msg_handler), GFP_NOFS);
+	if (nmh == NULL) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	nmh->nh_func = func;
+	nmh->nh_func_data = data;
+	nmh->nh_post_func = post_func;
+	nmh->nh_msg_type = msg_type;
+	nmh->nh_max_len = max_len;
+	nmh->nh_key = key;
+	/* the tree and list get this ref.. they're both removed in
+	 * unregister when this ref is dropped */
+	kref_init(&nmh->nh_kref);
+	INIT_LIST_HEAD(&nmh->nh_unregister_item);
+
+	write_lock(&r2net_handler_lock);
+	if (r2net_handler_tree_lookup(msg_type, key, &p, &parent))
+		ret = -EEXIST;
+	else {
+		rb_link_node(&nmh->nh_node, parent, p);
+		rb_insert_color(&nmh->nh_node, &r2net_handler_tree);
+		list_add_tail(&nmh->nh_unregister_item, unreg_list);
+
+		mlog(ML_TCP, "registered handler func %p type %u key %08x\n",
+		     func, msg_type, key);
+		/* we've had some trouble with handlers seemingly vanishing. */
+		mlog_bug_on_msg(r2net_handler_tree_lookup(msg_type, key, &p,
+							  &parent) == NULL,
+				"couldn't find handler we *just* registered "
+				"for type %u key %08x\n", msg_type, key);
+	}
+	write_unlock(&r2net_handler_lock);
+	if (ret)
+		goto out;
+
+out:
+	if (ret)
+		kfree(nmh);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(r2net_register_handler);
+
+void r2net_unregister_handler_list(struct list_head *list)
+{
+	struct r2net_msg_handler *nmh, *n;
+
+	write_lock(&r2net_handler_lock);
+	list_for_each_entry_safe(nmh, n, list, nh_unregister_item) {
+		mlog(ML_TCP, "unregistering handler func %p type %u key %08x\n",
+		     nmh->nh_func, nmh->nh_msg_type, nmh->nh_key);
+		rb_erase(&nmh->nh_node, &r2net_handler_tree);
+		list_del_init(&nmh->nh_unregister_item);
+		kref_put(&nmh->nh_kref, r2net_handler_kref_release);
+	}
+	write_unlock(&r2net_handler_lock);
+}
+EXPORT_SYMBOL_GPL(r2net_unregister_handler_list);
+
+static struct r2net_msg_handler *r2net_handler_get(u32 msg_type, u32 key)
+{
+	struct r2net_msg_handler *nmh;
+
+	read_lock(&r2net_handler_lock);
+	nmh = r2net_handler_tree_lookup(msg_type, key, NULL, NULL);
+	if (nmh)
+		kref_get(&nmh->nh_kref);
+	read_unlock(&r2net_handler_lock);
+
+	return nmh;
+}
+
+/* ------------------------------------------------------------ */
+
+static int r2net_recv_tcp_msg(struct socket *sock, void *data, size_t len)
+{
+	int ret;
+	mm_segment_t oldfs;
+	struct kvec vec = {
+		.iov_len = len,
+		.iov_base = data,
+	};
+	struct msghdr msg = {
+		.msg_iovlen = 1,
+		.msg_iov = (struct iovec *)&vec,
+		.msg_flags = MSG_DONTWAIT,
+	};
+
+	oldfs = get_fs();
+	set_fs(get_ds());
+	ret = sock_recvmsg(sock, &msg, len, msg.msg_flags);
+	set_fs(oldfs);
+
+	return ret;
+}
+
+static int r2net_send_tcp_msg(struct socket *sock, struct kvec *vec,
+			      size_t veclen, size_t total)
+{
+	int ret;
+	mm_segment_t oldfs;
+	struct msghdr msg = {
+		.msg_iov = (struct iovec *)vec,
+		.msg_iovlen = veclen,
+	};
+
+	if (sock == NULL) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	oldfs = get_fs();
+	set_fs(get_ds());
+	ret = sock_sendmsg(sock, &msg, total);
+	set_fs(oldfs);
+	if (ret != total) {
+		mlog(ML_ERROR, "sendmsg returned %d instead of %zu\n", ret,
+		     total);
+		if (ret >= 0)
+			ret = -EPIPE; /* should be smarter, I bet */
+		goto out;
+	}
+
+	ret = 0;
+out:
+	if (ret < 0)
+		mlog(0, "returning error: %d\n", ret);
+	return ret;
+}
+
+static void r2net_sendpage(struct r2net_sock_container *sc,
+			   void *kmalloced_virt,
+			   size_t size)
+{
+	struct r2net_node *nn = r2net_nn_from_num(sc->sc_node->nd_num);
+	ssize_t ret;
+
+	while (1) {
+		mutex_lock(&sc->sc_send_lock);
+		ret = sc->sc_sock->ops->sendpage(sc->sc_sock,
+					virt_to_page(kmalloced_virt),
+					(long)kmalloced_virt & ~PAGE_MASK,
+					size, MSG_DONTWAIT);
+		mutex_unlock(&sc->sc_send_lock);
+		if (ret == size)
+			break;
+		if (ret == (ssize_t)-EAGAIN) {
+			mlog(0, "sendpage of size %zu to " SC_NODEF_FMT
+			     " returned EAGAIN\n", size, sc->sc_node->nd_name,
+				sc->sc_node->nd_num,
+				&sc->sc_node->nd_ipv4_address,
+				ntohs(sc->sc_node->nd_ipv4_port));
+			cond_resched();
+			continue;
+		}
+		mlog(ML_ERROR, "sendpage of size %zu to " SC_NODEF_FMT
+		     " failed with %zd\n", size, sc->sc_node->nd_name,
+			sc->sc_node->nd_num, &sc->sc_node->nd_ipv4_address,
+			ntohs(sc->sc_node->nd_ipv4_port), ret);
+		r2net_ensure_shutdown(nn, sc, 0);
+		break;
+	}
+}
+
+static void r2net_init_msg(struct r2net_msg *msg, u16 data_len,
+				u16 msg_type, u32 key)
+{
+	memset(msg, 0, sizeof(struct r2net_msg));
+	msg->magic = cpu_to_be16(R2NET_MSG_MAGIC);
+	msg->data_len = cpu_to_be16(data_len);
+	msg->msg_type = cpu_to_be16(msg_type);
+	msg->sys_status = cpu_to_be32(R2NET_ERR_NONE);
+	msg->status = 0;
+	msg->key = cpu_to_be32(key);
+}
+
+static int r2net_tx_can_proceed(struct r2net_node *nn,
+				struct r2net_sock_container **sc_ret,
+				int *error)
+{
+	int ret = 0;
+
+	spin_lock(&nn->nn_lock);
+	if (nn->nn_persistent_error) {
+		ret = 1;
+		*sc_ret = NULL;
+		*error = nn->nn_persistent_error;
+	} else if (nn->nn_sc_valid) {
+		kref_get(&nn->nn_sc->sc_kref);
+
+		ret = 1;
+		*sc_ret = nn->nn_sc;
+		*error = 0;
+	}
+	spin_unlock(&nn->nn_lock);
+
+	return ret;
+}
+
+/* Get a map of all nodes to which this node is currently connected to */
+void r2net_fill_node_map(unsigned long *map, unsigned bytes)
+{
+	struct r2net_sock_container *sc;
+	int node, ret;
+
+	BUG_ON(bytes < (BITS_TO_LONGS(R2NM_MAX_NODES) * sizeof(unsigned long)));
+
+	memset(map, 0, bytes);
+	for (node = 0; node < R2NM_MAX_NODES; ++node) {
+		r2net_tx_can_proceed(r2net_nn_from_num(node), &sc, &ret);
+		if (!ret) {
+			set_bit(node, map);
+			sc_put(sc);
+		}
+	}
+}
+EXPORT_SYMBOL_GPL(r2net_fill_node_map);
+
+int r2net_send_message_vec(u32 msg_type, u32 key, struct kvec *caller_vec,
+			   size_t caller_veclen, u8 target_node, int *status)
+{
+	int ret = 0;
+	struct r2net_msg *msg = NULL;
+	size_t veclen, caller_bytes = 0;
+	struct kvec *vec = NULL;
+	struct r2net_sock_container *sc = NULL;
+	struct r2net_node *nn = r2net_nn_from_num(target_node);
+	struct r2net_status_wait nsw = {
+		.ns_node_item = LIST_HEAD_INIT(nsw.ns_node_item),
+	};
+	struct r2net_send_tracking nst;
+
+	/* this may be a general bug fix */
+	init_waitqueue_head(&nsw.ns_wq);
+
+	r2net_init_nst(&nst, msg_type, key, current, target_node);
+
+	if (r2net_wq == NULL) {
+		mlog(0, "attempt to tx without r2netd running\n");
+		ret = -ESRCH;
+		goto out;
+	}
+
+	if (caller_veclen == 0) {
+		mlog(0, "bad kvec array length\n");
+		ret = -EINVAL;
+		goto out;
+	}
+
+	caller_bytes = iov_length((struct iovec *)caller_vec, caller_veclen);
+	if (caller_bytes > R2NET_MAX_PAYLOAD_BYTES) {
+		mlog(0, "total payload len %zu too large\n", caller_bytes);
+		ret = -EINVAL;
+		goto out;
+	}
+
+	if (target_node == r2nm_this_node()) {
+		ret = -ELOOP;
+		goto out;
+	}
+
+	r2net_debug_add_nst(&nst);
+
+	r2net_set_nst_sock_time(&nst);
+
+	wait_event(nn->nn_sc_wq, r2net_tx_can_proceed(nn, &sc, &ret));
+	if (ret)
+		goto out;
+
+	r2net_set_nst_sock_container(&nst, sc);
+
+	veclen = caller_veclen + 1;
+	vec = kmalloc(sizeof(struct kvec) * veclen, GFP_ATOMIC);
+	if (vec == NULL) {
+		mlog(0, "failed to %zu element kvec!\n", veclen);
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	msg = kmalloc(sizeof(struct r2net_msg), GFP_ATOMIC);
+	if (!msg) {
+		mlog(0, "failed to allocate a r2net_msg!\n");
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	r2net_init_msg(msg, caller_bytes, msg_type, key);
+
+	vec[0].iov_len = sizeof(struct r2net_msg);
+	vec[0].iov_base = msg;
+	memcpy(&vec[1], caller_vec, caller_veclen * sizeof(struct kvec));
+
+	ret = r2net_prep_nsw(nn, &nsw);
+	if (ret)
+		goto out;
+
+	msg->msg_num = cpu_to_be32(nsw.ns_id);
+	r2net_set_nst_msg_id(&nst, nsw.ns_id);
+
+	r2net_set_nst_send_time(&nst);
+
+	/* finally, convert the message header to network byte-order
+	 * and send */
+	mutex_lock(&sc->sc_send_lock);
+	ret = r2net_send_tcp_msg(sc->sc_sock, vec, veclen,
+				 sizeof(struct r2net_msg) + caller_bytes);
+	mutex_unlock(&sc->sc_send_lock);
+	msglog(msg, "sending returned %d\n", ret);
+	if (ret < 0) {
+		mlog(0, "error returned from r2net_send_tcp_msg=%d\n", ret);
+		goto out;
+	}
+
+	/* wait on other node's handler */
+	r2net_set_nst_status_time(&nst);
+	wait_event(nsw.ns_wq, r2net_nsw_completed(nn, &nsw) ||
+			nn->nn_persistent_error || !nn->nn_sc_valid);
+
+	r2net_update_send_stats(&nst, sc);
+
+	/* Note that we avoid overwriting the callers status return
+	 * variable if a system error was reported on the other
+	 * side. Callers beware. */
+	ret = r2net_sys_err_to_errno(nsw.ns_sys_status);
+	if (status && !ret)
+		*status = nsw.ns_status;
+
+	mlog(0, "woken, returning system status %d, user status %d\n",
+	     ret, nsw.ns_status);
+out:
+	r2net_debug_del_nst(&nst); /* must be before dropping sc and node */
+	if (sc)
+		sc_put(sc);
+	kfree(vec);
+	kfree(msg);
+	r2net_complete_nsw(nn, &nsw, 0, 0, 0);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(r2net_send_message_vec);
+
+int r2net_send_message(u32 msg_type, u32 key, void *data, u32 len,
+		       u8 target_node, int *status)
+{
+	struct kvec vec = {
+		.iov_base = data,
+		.iov_len = len,
+	};
+	return r2net_send_message_vec(msg_type, key, &vec, 1,
+				      target_node, status);
+}
+EXPORT_SYMBOL_GPL(r2net_send_message);
+
+static int r2net_send_status_magic(struct socket *sock, struct r2net_msg *hdr,
+				   enum r2net_system_error syserr, int err)
+{
+	struct kvec vec = {
+		.iov_base = hdr,
+		.iov_len = sizeof(struct r2net_msg),
+	};
+
+	BUG_ON(syserr >= R2NET_ERR_MAX);
+
+	/* leave other fields intact from the incoming message, msg_num
+	 * in particular */
+	hdr->sys_status = cpu_to_be32(syserr);
+	hdr->status = cpu_to_be32(err);
+	/* twiddle the magic */
+	hdr->magic = cpu_to_be16(R2NET_MSG_STATUS_MAGIC);
+	hdr->data_len = 0;
+
+	msglog(hdr, "about to send status magic %d\n", err);
+	/* hdr has been in host byteorder this whole time */
+	return r2net_send_tcp_msg(sock, &vec, 1, sizeof(struct r2net_msg));
+}
+
+/*
+ * "data magic" is a long version of "status magic" where the message
+ * payload actually contains data to be passed in reply to certain messages
+ */
+static int r2net_send_data_magic(struct r2net_sock_container *sc,
+			  struct r2net_msg *hdr,
+			  void *data, size_t data_len,
+			  enum r2net_system_error syserr, int err)
+{
+	struct kvec vec[2];
+	int ret;
+
+	vec[0].iov_base = hdr;
+	vec[0].iov_len = sizeof(struct r2net_msg);
+	vec[1].iov_base = data;
+	vec[1].iov_len = data_len;
+
+	BUG_ON(syserr >= R2NET_ERR_MAX);
+
+	/* leave other fields intact from the incoming message, msg_num
+	 * in particular */
+	hdr->sys_status = cpu_to_be32(syserr);
+	hdr->status = cpu_to_be32(err);
+	hdr->magic = cpu_to_be16(R2NET_MSG_DATA_MAGIC);  /* twiddle magic */
+	hdr->data_len = cpu_to_be16(data_len);
+
+	msglog(hdr, "about to send data magic %d\n", err);
+	/* hdr has been in host byteorder this whole time */
+	ret = r2net_send_tcp_msg(sc->sc_sock, vec, 2,
+			sizeof(struct r2net_msg) + data_len);
+	return ret;
+}
+
+/*
+ * called by a message handler to convert an otherwise normal reply
+ * message into a "data magic" message
+ */
+void r2net_force_data_magic(struct r2net_msg *hdr, u16 msgtype, u32 msgkey)
+{
+	hdr->magic = cpu_to_be16(R2NET_MSG_DATA_MAGIC);
+	hdr->msg_type = cpu_to_be16(msgtype);
+	hdr->key = cpu_to_be32(msgkey);
+}
+
+/* this returns -errno if the header was unknown or too large, etc.
+ * after this is called the buffer us reused for the next message */
+static int r2net_process_message(struct r2net_sock_container *sc,
+				 struct r2net_msg *hdr)
+{
+	struct r2net_node *nn = r2net_nn_from_num(sc->sc_node->nd_num);
+	int ret = 0, handler_status;
+	enum  r2net_system_error syserr;
+	struct r2net_msg_handler *nmh = NULL;
+	void *ret_data = NULL;
+	int data_magic = 0;
+
+	msglog(hdr, "processing message\n");
+
+	r2net_sc_postpone_idle(sc);
+
+	switch (be16_to_cpu(hdr->magic)) {
+
+	case R2NET_MSG_STATUS_MAGIC:
+		/* special type for returning message status */
+		r2net_complete_nsw(nn, NULL, be32_to_cpu(hdr->msg_num),
+						be32_to_cpu(hdr->sys_status),
+						be32_to_cpu(hdr->status));
+		goto out;
+	case R2NET_MSG_KEEP_REQ_MAGIC:
+		r2net_sendpage(sc, r2net_keep_resp, sizeof(*r2net_keep_resp));
+		goto out;
+	case R2NET_MSG_KEEP_RESP_MAGIC:
+		goto out;
+	case R2NET_MSG_MAGIC:
+		break;
+	case R2NET_MSG_DATA_MAGIC:
+		/*
+		 * unlike a normal status magic, a data magic DOES
+		 * (MUST) have a handler, so the control flow is
+		 * a little funky here as a result
+		 */
+		data_magic = 1;
+		break;
+	default:
+		msglog(hdr, "bad magic\n");
+		ret = -EINVAL;
+		goto out;
+		break;
+	}
+
+	/* find a handler for it */
+	handler_status = 0;
+	nmh = r2net_handler_get(be16_to_cpu(hdr->msg_type),
+				be32_to_cpu(hdr->key));
+	if (!nmh) {
+		mlog(ML_TCP, "couldn't find handler for type %u key %08x\n",
+		     be16_to_cpu(hdr->msg_type), be32_to_cpu(hdr->key));
+		syserr = R2NET_ERR_NO_HNDLR;
+		goto out_respond;
+	}
+
+	syserr = R2NET_ERR_NONE;
+
+	if (be16_to_cpu(hdr->data_len) > nmh->nh_max_len)
+		syserr = R2NET_ERR_OVERFLOW;
+
+	if (syserr != R2NET_ERR_NONE) {
+		pr_err("ramster_r2net, message length problem\n");
+		goto out_respond;
+	}
+
+	r2net_set_func_start_time(sc);
+	sc->sc_msg_key = be32_to_cpu(hdr->key);
+	sc->sc_msg_type = be16_to_cpu(hdr->msg_type);
+	handler_status = (nmh->nh_func)(hdr, sizeof(struct r2net_msg) +
+					     be16_to_cpu(hdr->data_len),
+					nmh->nh_func_data, &ret_data);
+	if (data_magic) {
+		/*
+		 * handler handled data sent in reply to request
+		 * so complete the transaction
+		 */
+		r2net_complete_nsw(nn, NULL, be32_to_cpu(hdr->msg_num),
+			be32_to_cpu(hdr->sys_status), handler_status);
+		goto out;
+	}
+	/*
+	 * handler changed magic to DATA_MAGIC to reply to request for data,
+	 * implies ret_data points to data to return and handler_status
+	 * is the number of bytes of data
+	 */
+	if (be16_to_cpu(hdr->magic) == R2NET_MSG_DATA_MAGIC) {
+		ret = r2net_send_data_magic(sc, hdr,
+						ret_data, handler_status,
+						syserr, 0);
+		hdr = NULL;
+		mlog(0, "sending data reply %d, syserr %d returned %d\n",
+			handler_status, syserr, ret);
+		r2net_set_func_stop_time(sc);
+
+		r2net_update_recv_stats(sc);
+		goto out;
+	}
+	r2net_set_func_stop_time(sc);
+
+	r2net_update_recv_stats(sc);
+
+out_respond:
+	/* this destroys the hdr, so don't use it after this */
+	mutex_lock(&sc->sc_send_lock);
+	ret = r2net_send_status_magic(sc->sc_sock, hdr, syserr,
+				      handler_status);
+	mutex_unlock(&sc->sc_send_lock);
+	hdr = NULL;
+	mlog(0, "sending handler status %d, syserr %d returned %d\n",
+	     handler_status, syserr, ret);
+
+	if (nmh) {
+		BUG_ON(ret_data != NULL && nmh->nh_post_func == NULL);
+		if (nmh->nh_post_func)
+			(nmh->nh_post_func)(handler_status, nmh->nh_func_data,
+					    ret_data);
+	}
+
+out:
+	if (nmh)
+		r2net_handler_put(nmh);
+	return ret;
+}
+
+static int r2net_check_handshake(struct r2net_sock_container *sc)
+{
+	struct r2net_handshake *hand = page_address(sc->sc_page);
+	struct r2net_node *nn = r2net_nn_from_num(sc->sc_node->nd_num);
+
+	if (hand->protocol_version != cpu_to_be64(R2NET_PROTOCOL_VERSION)) {
+		pr_notice("ramster: " SC_NODEF_FMT " Advertised net "
+		       "protocol version %llu but %llu is required. "
+		       "Disconnecting.\n", sc->sc_node->nd_name,
+			sc->sc_node->nd_num, &sc->sc_node->nd_ipv4_address,
+			ntohs(sc->sc_node->nd_ipv4_port),
+		       (unsigned long long)be64_to_cpu(hand->protocol_version),
+		       R2NET_PROTOCOL_VERSION);
+
+		/* don't bother reconnecting if its the wrong version. */
+		r2net_ensure_shutdown(nn, sc, -ENOTCONN);
+		return -1;
+	}
+
+	/*
+	 * Ensure timeouts are consistent with other nodes, otherwise
+	 * we can end up with one node thinking that the other must be down,
+	 * but isn't. This can ultimately cause corruption.
+	 */
+	if (be32_to_cpu(hand->r2net_idle_timeout_ms) !=
+				r2net_idle_timeout()) {
+		pr_notice("ramster: " SC_NODEF_FMT " uses a network "
+		       "idle timeout of %u ms, but we use %u ms locally. "
+		       "Disconnecting.\n", sc->sc_node->nd_name,
+			sc->sc_node->nd_num, &sc->sc_node->nd_ipv4_address,
+			ntohs(sc->sc_node->nd_ipv4_port),
+		       be32_to_cpu(hand->r2net_idle_timeout_ms),
+		       r2net_idle_timeout());
+		r2net_ensure_shutdown(nn, sc, -ENOTCONN);
+		return -1;
+	}
+
+	if (be32_to_cpu(hand->r2net_keepalive_delay_ms) !=
+			r2net_keepalive_delay()) {
+		pr_notice("ramster: " SC_NODEF_FMT " uses a keepalive "
+		       "delay of %u ms, but we use %u ms locally. "
+		       "Disconnecting.\n", sc->sc_node->nd_name,
+			sc->sc_node->nd_num, &sc->sc_node->nd_ipv4_address,
+			ntohs(sc->sc_node->nd_ipv4_port),
+		       be32_to_cpu(hand->r2net_keepalive_delay_ms),
+		       r2net_keepalive_delay());
+		r2net_ensure_shutdown(nn, sc, -ENOTCONN);
+		return -1;
+	}
+
+	if (be32_to_cpu(hand->r2hb_heartbeat_timeout_ms) !=
+			R2HB_MAX_WRITE_TIMEOUT_MS) {
+		pr_notice("ramster: " SC_NODEF_FMT " uses a heartbeat "
+		       "timeout of %u ms, but we use %u ms locally. "
+		       "Disconnecting.\n", sc->sc_node->nd_name,
+			sc->sc_node->nd_num, &sc->sc_node->nd_ipv4_address,
+			ntohs(sc->sc_node->nd_ipv4_port),
+		       be32_to_cpu(hand->r2hb_heartbeat_timeout_ms),
+		       R2HB_MAX_WRITE_TIMEOUT_MS);
+		r2net_ensure_shutdown(nn, sc, -ENOTCONN);
+		return -1;
+	}
+
+	sc->sc_handshake_ok = 1;
+
+	spin_lock(&nn->nn_lock);
+	/* set valid and queue the idle timers only if it hasn't been
+	 * shut down already */
+	if (nn->nn_sc == sc) {
+		r2net_sc_reset_idle_timer(sc);
+		atomic_set(&nn->nn_timeout, 0);
+		r2net_set_nn_state(nn, sc, 1, 0);
+	}
+	spin_unlock(&nn->nn_lock);
+
+	/* shift everything up as though it wasn't there */
+	sc->sc_page_off -= sizeof(struct r2net_handshake);
+	if (sc->sc_page_off)
+		memmove(hand, hand + 1, sc->sc_page_off);
+
+	return 0;
+}
+
+/* this demuxes the queued rx bytes into header or payload bits and calls
+ * handlers as each full message is read off the socket.  it returns -error,
+ * == 0 eof, or > 0 for progress made.*/
+static int r2net_advance_rx(struct r2net_sock_container *sc)
+{
+	struct r2net_msg *hdr;
+	int ret = 0;
+	void *data;
+	size_t datalen;
+
+	sclog(sc, "receiving\n");
+	r2net_set_advance_start_time(sc);
+
+	if (unlikely(sc->sc_handshake_ok == 0)) {
+		if (sc->sc_page_off < sizeof(struct r2net_handshake)) {
+			data = page_address(sc->sc_page) + sc->sc_page_off;
+			datalen = sizeof(struct r2net_handshake) -
+							sc->sc_page_off;
+			ret = r2net_recv_tcp_msg(sc->sc_sock, data, datalen);
+			if (ret > 0)
+				sc->sc_page_off += ret;
+		}
+
+		if (sc->sc_page_off == sizeof(struct r2net_handshake)) {
+			r2net_check_handshake(sc);
+			if (unlikely(sc->sc_handshake_ok == 0))
+				ret = -EPROTO;
+		}
+		goto out;
+	}
+
+	/* do we need more header? */
+	if (sc->sc_page_off < sizeof(struct r2net_msg)) {
+		data = page_address(sc->sc_page) + sc->sc_page_off;
+		datalen = sizeof(struct r2net_msg) - sc->sc_page_off;
+		ret = r2net_recv_tcp_msg(sc->sc_sock, data, datalen);
+		if (ret > 0) {
+			sc->sc_page_off += ret;
+			/* only swab incoming here.. we can
+			 * only get here once as we cross from
+			 * being under to over */
+			if (sc->sc_page_off == sizeof(struct r2net_msg)) {
+				hdr = page_address(sc->sc_page);
+				if (be16_to_cpu(hdr->data_len) >
+				    R2NET_MAX_PAYLOAD_BYTES)
+					ret = -EOVERFLOW;
+				WARN_ON_ONCE(ret == -EOVERFLOW);
+			}
+		}
+		if (ret <= 0)
+			goto out;
+	}
+
+	if (sc->sc_page_off < sizeof(struct r2net_msg)) {
+		/* oof, still don't have a header */
+		goto out;
+	}
+
+	/* this was swabbed above when we first read it */
+	hdr = page_address(sc->sc_page);
+
+	msglog(hdr, "at page_off %zu\n", sc->sc_page_off);
+
+	/* do we need more payload? */
+	if (sc->sc_page_off - sizeof(struct r2net_msg) <
+					be16_to_cpu(hdr->data_len)) {
+		/* need more payload */
+		data = page_address(sc->sc_page) + sc->sc_page_off;
+		datalen = (sizeof(struct r2net_msg) +
+				be16_to_cpu(hdr->data_len)) -
+				sc->sc_page_off;
+		ret = r2net_recv_tcp_msg(sc->sc_sock, data, datalen);
+		if (ret > 0)
+			sc->sc_page_off += ret;
+		if (ret <= 0)
+			goto out;
+	}
+
+	if (sc->sc_page_off - sizeof(struct r2net_msg) ==
+						be16_to_cpu(hdr->data_len)) {
+		/* we can only get here once, the first time we read
+		 * the payload.. so set ret to progress if the handler
+		 * works out. after calling this the message is toast */
+		ret = r2net_process_message(sc, hdr);
+		if (ret == 0)
+			ret = 1;
+		sc->sc_page_off = 0;
+	}
+
+out:
+	sclog(sc, "ret = %d\n", ret);
+	r2net_set_advance_stop_time(sc);
+	return ret;
+}
+
+/* this work func is triggerd by data ready.  it reads until it can read no
+ * more.  it interprets 0, eof, as fatal.  if data_ready hits while we're doing
+ * our work the work struct will be marked and we'll be called again. */
+static void r2net_rx_until_empty(struct work_struct *work)
+{
+	struct r2net_sock_container *sc =
+		container_of(work, struct r2net_sock_container, sc_rx_work);
+	int ret;
+
+	do {
+		ret = r2net_advance_rx(sc);
+	} while (ret > 0);
+
+	if (ret <= 0 && ret != -EAGAIN) {
+		struct r2net_node *nn = r2net_nn_from_num(sc->sc_node->nd_num);
+		sclog(sc, "saw error %d, closing\n", ret);
+		/* not permanent so read failed handshake can retry */
+		r2net_ensure_shutdown(nn, sc, 0);
+	}
+	sc_put(sc);
+}
+
+static int r2net_set_nodelay(struct socket *sock)
+{
+	int ret, val = 1;
+	mm_segment_t oldfs;
+
+	oldfs = get_fs();
+	set_fs(KERNEL_DS);
+
+	/*
+	 * Dear unsuspecting programmer,
+	 *
+	 * Don't use sock_setsockopt() for SOL_TCP.  It doesn't check its level
+	 * argument and assumes SOL_SOCKET so, say, your TCP_NODELAY will
+	 * silently turn into SO_DEBUG.
+	 *
+	 * Yours,
+	 * Keeper of hilariously fragile interfaces.
+	 */
+	ret = sock->ops->setsockopt(sock, SOL_TCP, TCP_NODELAY,
+				    (char __user *)&val, sizeof(val));
+
+	set_fs(oldfs);
+	return ret;
+}
+
+static void r2net_initialize_handshake(void)
+{
+	r2net_hand->r2hb_heartbeat_timeout_ms = cpu_to_be32(
+		R2HB_MAX_WRITE_TIMEOUT_MS);
+	r2net_hand->r2net_idle_timeout_ms = cpu_to_be32(r2net_idle_timeout());
+	r2net_hand->r2net_keepalive_delay_ms = cpu_to_be32(
+		r2net_keepalive_delay());
+	r2net_hand->r2net_reconnect_delay_ms = cpu_to_be32(
+		r2net_reconnect_delay());
+}
+
+/* ------------------------------------------------------------ */
+
+/* called when a connect completes and after a sock is accepted.  the
+ * rx path will see the response and mark the sc valid */
+static void r2net_sc_connect_completed(struct work_struct *work)
+{
+	struct r2net_sock_container *sc =
+			container_of(work, struct r2net_sock_container,
+			     sc_connect_work);
+
+	mlog(ML_MSG, "sc sending handshake with ver %llu id %llx\n",
+		(unsigned long long)R2NET_PROTOCOL_VERSION,
+		(unsigned long long)be64_to_cpu(r2net_hand->connector_id));
+
+	r2net_initialize_handshake();
+	r2net_sendpage(sc, r2net_hand, sizeof(*r2net_hand));
+	sc_put(sc);
+}
+
+/* this is called as a work_struct func. */
+static void r2net_sc_send_keep_req(struct work_struct *work)
+{
+	struct r2net_sock_container *sc =
+		container_of(work, struct r2net_sock_container,
+			     sc_keepalive_work.work);
+
+	r2net_sendpage(sc, r2net_keep_req, sizeof(*r2net_keep_req));
+	sc_put(sc);
+}
+
+/* socket shutdown does a del_timer_sync against this as it tears down.
+ * we can't start this timer until we've got to the point in sc buildup
+ * where shutdown is going to be involved */
+static void r2net_idle_timer(unsigned long data)
+{
+	struct r2net_sock_container *sc = (struct r2net_sock_container *)data;
+	struct r2net_node *nn = r2net_nn_from_num(sc->sc_node->nd_num);
+#ifdef CONFIG_DEBUG_FS
+	unsigned long msecs = ktime_to_ms(ktime_get()) -
+		ktime_to_ms(sc->sc_tv_timer);
+#else
+	unsigned long msecs = r2net_idle_timeout();
+#endif
+
+	pr_notice("ramster: Connection to " SC_NODEF_FMT " has been "
+	       "idle for %lu.%lu secs, shutting it down.\n",
+		sc->sc_node->nd_name, sc->sc_node->nd_num,
+		&sc->sc_node->nd_ipv4_address, ntohs(sc->sc_node->nd_ipv4_port),
+	       msecs / 1000, msecs % 1000);
+
+	/*
+	 * Initialize the nn_timeout so that the next connection attempt
+	 * will continue in r2net_start_connect.
+	 */
+	atomic_set(&nn->nn_timeout, 1);
+	r2net_sc_queue_work(sc, &sc->sc_shutdown_work);
+}
+
+static void r2net_sc_reset_idle_timer(struct r2net_sock_container *sc)
+{
+	r2net_sc_cancel_delayed_work(sc, &sc->sc_keepalive_work);
+	r2net_sc_queue_delayed_work(sc, &sc->sc_keepalive_work,
+		      msecs_to_jiffies(r2net_keepalive_delay()));
+	r2net_set_sock_timer(sc);
+	mod_timer(&sc->sc_idle_timeout,
+	       jiffies + msecs_to_jiffies(r2net_idle_timeout()));
+}
+
+static void r2net_sc_postpone_idle(struct r2net_sock_container *sc)
+{
+	/* Only push out an existing timer */
+	if (timer_pending(&sc->sc_idle_timeout))
+		r2net_sc_reset_idle_timer(sc);
+}
+
+/* this work func is kicked whenever a path sets the nn state which doesn't
+ * have valid set.  This includes seeing hb come up, losing a connection,
+ * having a connect attempt fail, etc. This centralizes the logic which decides
+ * if a connect attempt should be made or if we should give up and all future
+ * transmit attempts should fail */
+static void r2net_start_connect(struct work_struct *work)
+{
+	struct r2net_node *nn =
+		container_of(work, struct r2net_node, nn_connect_work.work);
+	struct r2net_sock_container *sc = NULL;
+	struct r2nm_node *node = NULL, *mynode = NULL;
+	struct socket *sock = NULL;
+	struct sockaddr_in myaddr = {0, }, remoteaddr = {0, };
+	int ret = 0, stop;
+	unsigned int timeout;
+
+	/* if we're greater we initiate tx, otherwise we accept */
+	if (r2nm_this_node() <= r2net_num_from_nn(nn))
+		goto out;
+
+	/* watch for racing with tearing a node down */
+	node = r2nm_get_node_by_num(r2net_num_from_nn(nn));
+	if (node == NULL) {
+		ret = 0;
+		goto out;
+	}
+
+	mynode = r2nm_get_node_by_num(r2nm_this_node());
+	if (mynode == NULL) {
+		ret = 0;
+		goto out;
+	}
+
+	spin_lock(&nn->nn_lock);
+	/*
+	 * see if we already have one pending or have given up.
+	 * For nn_timeout, it is set when we close the connection
+	 * because of the idle time out. So it means that we have
+	 * at least connected to that node successfully once,
+	 * now try to connect to it again.
+	 */
+	timeout = atomic_read(&nn->nn_timeout);
+	stop = (nn->nn_sc ||
+		(nn->nn_persistent_error &&
+		(nn->nn_persistent_error != -ENOTCONN || timeout == 0)));
+	spin_unlock(&nn->nn_lock);
+	if (stop)
+		goto out;
+
+	nn->nn_last_connect_attempt = jiffies;
+
+	sc = sc_alloc(node);
+	if (sc == NULL) {
+		mlog(0, "couldn't allocate sc\n");
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	ret = sock_create(PF_INET, SOCK_STREAM, IPPROTO_TCP, &sock);
+	if (ret < 0) {
+		mlog(0, "can't create socket: %d\n", ret);
+		goto out;
+	}
+	sc->sc_sock = sock; /* freed by sc_kref_release */
+
+	sock->sk->sk_allocation = GFP_ATOMIC;
+
+	myaddr.sin_family = AF_INET;
+	myaddr.sin_addr.s_addr = mynode->nd_ipv4_address;
+	myaddr.sin_port = htons(0); /* any port */
+
+	ret = sock->ops->bind(sock, (struct sockaddr *)&myaddr,
+			      sizeof(myaddr));
+	if (ret) {
+		mlog(ML_ERROR, "bind failed with %d at address %pI4\n",
+		     ret, &mynode->nd_ipv4_address);
+		goto out;
+	}
+
+	ret = r2net_set_nodelay(sc->sc_sock);
+	if (ret) {
+		mlog(ML_ERROR, "setting TCP_NODELAY failed with %d\n", ret);
+		goto out;
+	}
+
+	r2net_register_callbacks(sc->sc_sock->sk, sc);
+
+	spin_lock(&nn->nn_lock);
+	/* handshake completion will set nn->nn_sc_valid */
+	r2net_set_nn_state(nn, sc, 0, 0);
+	spin_unlock(&nn->nn_lock);
+
+	remoteaddr.sin_family = AF_INET;
+	remoteaddr.sin_addr.s_addr = node->nd_ipv4_address;
+	remoteaddr.sin_port = node->nd_ipv4_port;
+
+	ret = sc->sc_sock->ops->connect(sc->sc_sock,
+					(struct sockaddr *)&remoteaddr,
+					sizeof(remoteaddr),
+					O_NONBLOCK);
+	if (ret == -EINPROGRESS)
+		ret = 0;
+
+out:
+	if (ret) {
+		pr_notice("ramster: Connect attempt to " SC_NODEF_FMT
+		       " failed with errno %d\n", sc->sc_node->nd_name,
+			sc->sc_node->nd_num, &sc->sc_node->nd_ipv4_address,
+			ntohs(sc->sc_node->nd_ipv4_port), ret);
+		/* 0 err so that another will be queued and attempted
+		 * from set_nn_state */
+		if (sc)
+			r2net_ensure_shutdown(nn, sc, 0);
+	}
+	if (sc)
+		sc_put(sc);
+	if (node)
+		r2nm_node_put(node);
+	if (mynode)
+		r2nm_node_put(mynode);
+
+	return;
+}
+
+static void r2net_connect_expired(struct work_struct *work)
+{
+	struct r2net_node *nn =
+		container_of(work, struct r2net_node, nn_connect_expired.work);
+
+	spin_lock(&nn->nn_lock);
+	if (!nn->nn_sc_valid) {
+		pr_notice("ramster: No connection established with "
+		       "node %u after %u.%u seconds, giving up.\n",
+		     r2net_num_from_nn(nn),
+		     r2net_idle_timeout() / 1000,
+		     r2net_idle_timeout() % 1000);
+
+		r2net_set_nn_state(nn, NULL, 0, -ENOTCONN);
+	}
+	spin_unlock(&nn->nn_lock);
+}
+
+static void r2net_still_up(struct work_struct *work)
+{
+}
+
+/* ------------------------------------------------------------ */
+
+void r2net_disconnect_node(struct r2nm_node *node)
+{
+	struct r2net_node *nn = r2net_nn_from_num(node->nd_num);
+
+	/* don't reconnect until it's heartbeating again */
+	spin_lock(&nn->nn_lock);
+	atomic_set(&nn->nn_timeout, 0);
+	r2net_set_nn_state(nn, NULL, 0, -ENOTCONN);
+	spin_unlock(&nn->nn_lock);
+
+	if (r2net_wq) {
+		cancel_delayed_work(&nn->nn_connect_expired);
+		cancel_delayed_work(&nn->nn_connect_work);
+		cancel_delayed_work(&nn->nn_still_up);
+		flush_workqueue(r2net_wq);
+	}
+}
+
+static void r2net_hb_node_down_cb(struct r2nm_node *node, int node_num,
+				  void *data)
+{
+	if (!node)
+		return;
+
+	if (node_num != r2nm_this_node())
+		r2net_disconnect_node(node);
+
+	BUG_ON(atomic_read(&r2net_connected_peers) < 0);
+}
+
+static void r2net_hb_node_up_cb(struct r2nm_node *node, int node_num,
+				void *data)
+{
+	struct r2net_node *nn = r2net_nn_from_num(node_num);
+
+	BUG_ON(!node);
+
+	/* ensure an immediate connect attempt */
+	nn->nn_last_connect_attempt = jiffies -
+		(msecs_to_jiffies(r2net_reconnect_delay()) + 1);
+
+	if (node_num != r2nm_this_node()) {
+		/* believe it or not, accept and node hearbeating testing
+		 * can succeed for this node before we got here.. so
+		 * only use set_nn_state to clear the persistent error
+		 * if that hasn't already happened */
+		spin_lock(&nn->nn_lock);
+		atomic_set(&nn->nn_timeout, 0);
+		if (nn->nn_persistent_error)
+			r2net_set_nn_state(nn, NULL, 0, 0);
+		spin_unlock(&nn->nn_lock);
+	}
+}
+
+void r2net_unregister_hb_callbacks(void)
+{
+	r2hb_unregister_callback(NULL, &r2net_hb_up);
+	r2hb_unregister_callback(NULL, &r2net_hb_down);
+}
+
+int r2net_register_hb_callbacks(void)
+{
+	int ret;
+
+	r2hb_setup_callback(&r2net_hb_down, R2HB_NODE_DOWN_CB,
+			    r2net_hb_node_down_cb, NULL, R2NET_HB_PRI);
+	r2hb_setup_callback(&r2net_hb_up, R2HB_NODE_UP_CB,
+			    r2net_hb_node_up_cb, NULL, R2NET_HB_PRI);
+
+	ret = r2hb_register_callback(NULL, &r2net_hb_up);
+	if (ret == 0)
+		ret = r2hb_register_callback(NULL, &r2net_hb_down);
+
+	if (ret)
+		r2net_unregister_hb_callbacks();
+
+	return ret;
+}
+
+/* ------------------------------------------------------------ */
+
+static int r2net_accept_one(struct socket *sock)
+{
+	int ret, slen;
+	struct sockaddr_in sin;
+	struct socket *new_sock = NULL;
+	struct r2nm_node *node = NULL;
+	struct r2nm_node *local_node = NULL;
+	struct r2net_sock_container *sc = NULL;
+	struct r2net_node *nn;
+
+	BUG_ON(sock == NULL);
+	ret = sock_create_lite(sock->sk->sk_family, sock->sk->sk_type,
+			       sock->sk->sk_protocol, &new_sock);
+	if (ret)
+		goto out;
+
+	new_sock->type = sock->type;
+	new_sock->ops = sock->ops;
+	ret = sock->ops->accept(sock, new_sock, O_NONBLOCK);
+	if (ret < 0)
+		goto out;
+
+	new_sock->sk->sk_allocation = GFP_ATOMIC;
+
+	ret = r2net_set_nodelay(new_sock);
+	if (ret) {
+		mlog(ML_ERROR, "setting TCP_NODELAY failed with %d\n", ret);
+		goto out;
+	}
+
+	slen = sizeof(sin);
+	ret = new_sock->ops->getname(new_sock, (struct sockaddr *) &sin,
+				       &slen, 1);
+	if (ret < 0)
+		goto out;
+
+	node = r2nm_get_node_by_ip(sin.sin_addr.s_addr);
+	if (node == NULL) {
+		pr_notice("ramster: Attempt to connect from unknown "
+		       "node at %pI4:%d\n", &sin.sin_addr.s_addr,
+		       ntohs(sin.sin_port));
+		ret = -EINVAL;
+		goto out;
+	}
+
+	if (r2nm_this_node() >= node->nd_num) {
+		local_node = r2nm_get_node_by_num(r2nm_this_node());
+		pr_notice("ramster: Unexpected connect attempt seen "
+		       "at node '%s' (%u, %pI4:%d) from node '%s' (%u, "
+		       "%pI4:%d)\n", local_node->nd_name, local_node->nd_num,
+		       &(local_node->nd_ipv4_address),
+		       ntohs(local_node->nd_ipv4_port), node->nd_name,
+		       node->nd_num, &sin.sin_addr.s_addr, ntohs(sin.sin_port));
+		ret = -EINVAL;
+		goto out;
+	}
+
+	/* this happens all the time when the other node sees our heartbeat
+	 * and tries to connect before we see their heartbeat */
+	if (!r2hb_check_node_heartbeating_from_callback(node->nd_num)) {
+		mlog(ML_CONN, "attempt to connect from node '%s' at "
+		     "%pI4:%d but it isn't heartbeating\n",
+		     node->nd_name, &sin.sin_addr.s_addr,
+		     ntohs(sin.sin_port));
+		ret = -EINVAL;
+		goto out;
+	}
+
+	nn = r2net_nn_from_num(node->nd_num);
+
+	spin_lock(&nn->nn_lock);
+	if (nn->nn_sc)
+		ret = -EBUSY;
+	else
+		ret = 0;
+	spin_unlock(&nn->nn_lock);
+	if (ret) {
+		pr_notice("ramster: Attempt to connect from node '%s' "
+		       "at %pI4:%d but it already has an open connection\n",
+		       node->nd_name, &sin.sin_addr.s_addr,
+		       ntohs(sin.sin_port));
+		goto out;
+	}
+
+	sc = sc_alloc(node);
+	if (sc == NULL) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	sc->sc_sock = new_sock;
+	new_sock = NULL;
+
+	spin_lock(&nn->nn_lock);
+	atomic_set(&nn->nn_timeout, 0);
+	r2net_set_nn_state(nn, sc, 0, 0);
+	spin_unlock(&nn->nn_lock);
+
+	r2net_register_callbacks(sc->sc_sock->sk, sc);
+	r2net_sc_queue_work(sc, &sc->sc_rx_work);
+
+	r2net_initialize_handshake();
+	r2net_sendpage(sc, r2net_hand, sizeof(*r2net_hand));
+
+out:
+	if (new_sock)
+		sock_release(new_sock);
+	if (node)
+		r2nm_node_put(node);
+	if (local_node)
+		r2nm_node_put(local_node);
+	if (sc)
+		sc_put(sc);
+	return ret;
+}
+
+static void r2net_accept_many(struct work_struct *work)
+{
+	struct socket *sock = r2net_listen_sock;
+	while (r2net_accept_one(sock) == 0)
+		cond_resched();
+}
+
+static void r2net_listen_data_ready(struct sock *sk, int bytes)
+{
+	void (*ready)(struct sock *sk, int bytes);
+
+	read_lock(&sk->sk_callback_lock);
+	ready = sk->sk_user_data;
+	if (ready == NULL) { /* check for teardown race */
+		ready = sk->sk_data_ready;
+		goto out;
+	}
+
+	/* ->sk_data_ready is also called for a newly established child socket
+	 * before it has been accepted and the acceptor has set up their
+	 * data_ready.. we only want to queue listen work for our listening
+	 * socket */
+	if (sk->sk_state == TCP_LISTEN) {
+		mlog(ML_TCP, "bytes: %d\n", bytes);
+		queue_work(r2net_wq, &r2net_listen_work);
+	}
+
+out:
+	read_unlock(&sk->sk_callback_lock);
+	ready(sk, bytes);
+}
+
+static int r2net_open_listening_sock(__be32 addr, __be16 port)
+{
+	struct socket *sock = NULL;
+	int ret;
+	struct sockaddr_in sin = {
+		.sin_family = PF_INET,
+		.sin_addr = { .s_addr = addr },
+		.sin_port = port,
+	};
+
+	ret = sock_create(PF_INET, SOCK_STREAM, IPPROTO_TCP, &sock);
+	if (ret < 0) {
+		pr_err("ramster: Error %d while creating socket\n", ret);
+		goto out;
+	}
+
+	sock->sk->sk_allocation = GFP_ATOMIC;
+
+	write_lock_bh(&sock->sk->sk_callback_lock);
+	sock->sk->sk_user_data = sock->sk->sk_data_ready;
+	sock->sk->sk_data_ready = r2net_listen_data_ready;
+	write_unlock_bh(&sock->sk->sk_callback_lock);
+
+	r2net_listen_sock = sock;
+	INIT_WORK(&r2net_listen_work, r2net_accept_many);
+
+	sock->sk->sk_reuse = /* SK_CAN_REUSE FIXME FOR 3.4 */ 1;
+	ret = sock->ops->bind(sock, (struct sockaddr *)&sin, sizeof(sin));
+	if (ret < 0) {
+		pr_err("ramster: Error %d while binding socket at %pI4:%u\n",
+			ret, &addr, ntohs(port));
+		goto out;
+	}
+
+	ret = sock->ops->listen(sock, 64);
+	if (ret < 0)
+		pr_err("ramster: Error %d while listening on %pI4:%u\n",
+		       ret, &addr, ntohs(port));
+
+out:
+	if (ret) {
+		r2net_listen_sock = NULL;
+		if (sock)
+			sock_release(sock);
+	}
+	return ret;
+}
+
+/*
+ * called from node manager when we should bring up our network listening
+ * socket.  node manager handles all the serialization to only call this
+ * once and to match it with r2net_stop_listening().  note,
+ * r2nm_this_node() doesn't work yet as we're being called while it
+ * is being set up.
+ */
+int r2net_start_listening(struct r2nm_node *node)
+{
+	int ret = 0;
+
+	BUG_ON(r2net_wq != NULL);
+	BUG_ON(r2net_listen_sock != NULL);
+
+	mlog(ML_KTHREAD, "starting r2net thread...\n");
+	r2net_wq = create_singlethread_workqueue("r2net");
+	if (r2net_wq == NULL) {
+		mlog(ML_ERROR, "unable to launch r2net thread\n");
+		return -ENOMEM; /* ? */
+	}
+
+	ret = r2net_open_listening_sock(node->nd_ipv4_address,
+					node->nd_ipv4_port);
+	if (ret) {
+		destroy_workqueue(r2net_wq);
+		r2net_wq = NULL;
+	}
+
+	return ret;
+}
+
+/* again, r2nm_this_node() doesn't work here as we're involved in
+ * tearing it down */
+void r2net_stop_listening(struct r2nm_node *node)
+{
+	struct socket *sock = r2net_listen_sock;
+	size_t i;
+
+	BUG_ON(r2net_wq == NULL);
+	BUG_ON(r2net_listen_sock == NULL);
+
+	/* stop the listening socket from generating work */
+	write_lock_bh(&sock->sk->sk_callback_lock);
+	sock->sk->sk_data_ready = sock->sk->sk_user_data;
+	sock->sk->sk_user_data = NULL;
+	write_unlock_bh(&sock->sk->sk_callback_lock);
+
+	for (i = 0; i < ARRAY_SIZE(r2net_nodes); i++) {
+		struct r2nm_node *node = r2nm_get_node_by_num(i);
+		if (node) {
+			r2net_disconnect_node(node);
+			r2nm_node_put(node);
+		}
+	}
+
+	/* finish all work and tear down the work queue */
+	mlog(ML_KTHREAD, "waiting for r2net thread to exit....\n");
+	destroy_workqueue(r2net_wq);
+	r2net_wq = NULL;
+
+	sock_release(r2net_listen_sock);
+	r2net_listen_sock = NULL;
+}
+
+void r2net_hb_node_up_manual(int node_num)
+{
+	struct r2nm_node dummy;
+	if (r2nm_single_cluster == NULL)
+		pr_err("ramster: cluster not alive, node_up_manual ignored\n");
+	else {
+		r2hb_manual_set_node_heartbeating(node_num);
+		r2net_hb_node_up_cb(&dummy, node_num, NULL);
+	}
+}
+
+/* ------------------------------------------------------------ */
+
+int r2net_init(void)
+{
+	unsigned long i;
+
+	if (r2net_debugfs_init())
+		return -ENOMEM;
+
+	r2net_hand = kzalloc(sizeof(struct r2net_handshake), GFP_KERNEL);
+	r2net_keep_req = kzalloc(sizeof(struct r2net_msg), GFP_KERNEL);
+	r2net_keep_resp = kzalloc(sizeof(struct r2net_msg), GFP_KERNEL);
+	if (!r2net_hand || !r2net_keep_req || !r2net_keep_resp) {
+		kfree(r2net_hand);
+		kfree(r2net_keep_req);
+		kfree(r2net_keep_resp);
+		return -ENOMEM;
+	}
+
+	r2net_hand->protocol_version = cpu_to_be64(R2NET_PROTOCOL_VERSION);
+	r2net_hand->connector_id = cpu_to_be64(1);
+
+	r2net_keep_req->magic = cpu_to_be16(R2NET_MSG_KEEP_REQ_MAGIC);
+	r2net_keep_resp->magic = cpu_to_be16(R2NET_MSG_KEEP_RESP_MAGIC);
+
+	for (i = 0; i < ARRAY_SIZE(r2net_nodes); i++) {
+		struct r2net_node *nn = r2net_nn_from_num(i);
+
+		atomic_set(&nn->nn_timeout, 0);
+		spin_lock_init(&nn->nn_lock);
+		INIT_DELAYED_WORK(&nn->nn_connect_work, r2net_start_connect);
+		INIT_DELAYED_WORK(&nn->nn_connect_expired,
+				  r2net_connect_expired);
+		INIT_DELAYED_WORK(&nn->nn_still_up, r2net_still_up);
+		/* until we see hb from a node we'll return einval */
+		nn->nn_persistent_error = -ENOTCONN;
+		init_waitqueue_head(&nn->nn_sc_wq);
+		idr_init(&nn->nn_status_idr);
+		INIT_LIST_HEAD(&nn->nn_status_list);
+	}
+
+	return 0;
+}
+
+void r2net_exit(void)
+{
+	kfree(r2net_hand);
+	kfree(r2net_keep_req);
+	kfree(r2net_keep_resp);
+	r2net_debugfs_exit();
+}