[PATCH] OCFS2: The Second Oracle Cluster Filesystem

Node messaging via tcp. Used by the dlm and the file system for point
to point communication between nodes.

Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
Signed-off-by: Kurt Hackel <kurt.hackel@oracle.com>

1 files changed, 1829 insertions, 0 deletions

diff --git a/fs/ocfs2/cluster/tcp.c b/fs/ocfs2/cluster/tcp.c
new file mode 100644
index 000000000000..35d92c01a972
--- /dev/null
+++ b/fs/ocfs2/cluster/tcp.c
@@ -0,0 +1,1829 @@
+/* -*- 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 <net/tcp.h>
+
+#include <asm/uaccess.h>
+
+#include "heartbeat.h"
+#include "tcp.h"
+#include "nodemanager.h"
+#define MLOG_MASK_PREFIX ML_TCP
+#include "masklog.h"
+#include "quorum.h"
+
+#include "tcp_internal.h"
+
+/* 
+ * The linux network stack isn't sparse endian clean.. It has macros like
+ * ntohs() which perform the endian checks and structs like sockaddr_in
+ * which aren't annotated.  So __force is found here to get the build
+ * clean.  When they emerge from the dark ages and annotate the code
+ * we can remove these.
+ */
+
+#define SC_NODEF_FMT "node %s (num %u) at %u.%u.%u.%u:%u"
+#define SC_NODEF_ARGS(sc) sc->sc_node->nd_name, sc->sc_node->nd_num,    \
+                          NIPQUAD(sc->sc_node->nd_ipv4_address),        \
+                          ntohs(sc->sc_node->nd_ipv4_port)
+
+/*
+ * 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 rwlock_t o2net_handler_lock = RW_LOCK_UNLOCKED;
+static struct rb_root o2net_handler_tree = RB_ROOT;
+
+static struct o2net_node o2net_nodes[O2NM_MAX_NODES];
+
+/* XXX someday we'll need better accounting */
+static struct socket *o2net_listen_sock = NULL;
+
+/*
+ * listen work is only queued by the listening socket callbacks on the
+ * o2net_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 quroum work, before canceling delayed quorum work and
+ * destroying the work queue.
+ */
+static struct workqueue_struct *o2net_wq;
+static struct work_struct o2net_listen_work;
+
+static struct o2hb_callback_func o2net_hb_up, o2net_hb_down;
+#define O2NET_HB_PRI 0x1
+
+static struct o2net_handshake *o2net_hand;
+static struct o2net_msg *o2net_keep_req, *o2net_keep_resp;
+
+static int o2net_sys_err_translations[O2NET_ERR_MAX] =
+                {[O2NET_ERR_NONE]       = 0,
+                 [O2NET_ERR_NO_HNDLR]   = -ENOPROTOOPT,
+                 [O2NET_ERR_OVERFLOW]   = -EOVERFLOW,
+                 [O2NET_ERR_DIED]       = -EHOSTDOWN,};
+
+/* can't quite avoid *all* internal declarations :/ */
+static void o2net_sc_connect_completed(void *arg);
+static void o2net_rx_until_empty(void *arg);
+static void o2net_shutdown_sc(void *arg);
+static void o2net_listen_data_ready(struct sock *sk, int bytes);
+static void o2net_sc_send_keep_req(void *arg);
+static void o2net_idle_timer(unsigned long data);
+static void o2net_sc_postpone_idle(struct o2net_sock_container *sc);
+
+static inline int o2net_sys_err_to_errno(enum o2net_system_error err)
+{
+        int trans;
+        BUG_ON(err >= O2NET_ERR_MAX);
+        trans = o2net_sys_err_translations[err];
+
+        /* Just in case we mess up the translation table above */
+        BUG_ON(err != O2NET_ERR_NONE && trans == 0);
+        return trans;
+}
+
+static struct o2net_node * o2net_nn_from_num(u8 node_num)
+{
+        BUG_ON(node_num >= ARRAY_SIZE(o2net_nodes));
+        return &o2net_nodes[node_num];
+}
+
+static u8 o2net_num_from_nn(struct o2net_node *nn)
+{
+        BUG_ON(nn == NULL);
+        return nn - o2net_nodes;
+}
+
+/* ------------------------------------------------------------ */
+
+static int o2net_prep_nsw(struct o2net_node *nn, struct o2net_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 = O2NET_ERR_NONE;
+                nsw->ns_status = 0;
+        }
+
+        return ret;
+}
+
+static void o2net_complete_nsw_locked(struct o2net_node *nn,
+                                      struct o2net_status_wait *nsw,
+                                      enum o2net_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 o2net_complete_nsw(struct o2net_node *nn,
+                               struct o2net_status_wait *nsw,
+                               u64 id, enum o2net_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;
+        }
+
+        o2net_complete_nsw_locked(nn, nsw, sys_status, status);
+
+out:
+        spin_unlock(&nn->nn_lock);
+        return;
+}
+
+static void o2net_complete_nodes_nsw(struct o2net_node *nn)
+{
+        struct list_head *iter, *tmp;
+        unsigned int num_kills = 0;
+        struct o2net_status_wait *nsw;
+
+        assert_spin_locked(&nn->nn_lock);
+
+        list_for_each_safe(iter, tmp, &nn->nn_status_list) {
+                nsw = list_entry(iter, struct o2net_status_wait, ns_node_item);
+                o2net_complete_nsw_locked(nn, nsw, O2NET_ERR_DIED, 0);
+                num_kills++;
+        }
+
+        mlog(0, "completed %d messages for node %u\n", num_kills,
+             o2net_num_from_nn(nn));
+}
+
+static int o2net_nsw_completed(struct o2net_node *nn,
+                               struct o2net_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 o2net_sock_container *sc = container_of(kref,
+                                        struct o2net_sock_container, sc_kref);
+        sclog(sc, "releasing\n");
+
+        if (sc->sc_sock) {
+                sock_release(sc->sc_sock);
+                sc->sc_sock = NULL;
+        }
+
+        o2nm_node_put(sc->sc_node);
+        sc->sc_node = NULL;
+
+        kfree(sc);
+}
+
+static void sc_put(struct o2net_sock_container *sc)
+{
+        sclog(sc, "put\n");
+        kref_put(&sc->sc_kref, sc_kref_release);
+}
+static void sc_get(struct o2net_sock_container *sc)
+{
+        sclog(sc, "get\n");
+        kref_get(&sc->sc_kref);
+}
+static struct o2net_sock_container *sc_alloc(struct o2nm_node *node)
+{
+        struct o2net_sock_container *sc, *ret = NULL;
+        struct page *page = NULL;
+
+        page = alloc_page(GFP_NOFS);
+        sc = kcalloc(1, sizeof(*sc), GFP_NOFS);
+        if (sc == NULL || page == NULL)
+                goto out;
+
+        kref_init(&sc->sc_kref);
+        o2nm_node_get(node);
+        sc->sc_node = node;
+
+        INIT_WORK(&sc->sc_connect_work, o2net_sc_connect_completed, sc);
+        INIT_WORK(&sc->sc_rx_work, o2net_rx_until_empty, sc);
+        INIT_WORK(&sc->sc_shutdown_work, o2net_shutdown_sc, sc);
+        INIT_WORK(&sc->sc_keepalive_work, o2net_sc_send_keep_req, sc);
+
+        init_timer(&sc->sc_idle_timeout);
+        sc->sc_idle_timeout.function = o2net_idle_timer;
+        sc->sc_idle_timeout.data = (unsigned long)sc;
+
+        sclog(sc, "alloced\n");
+
+        ret = sc;
+        sc->sc_page = page;
+        sc = NULL;
+        page = NULL;
+
+out:
+        if (page)
+                __free_page(page);
+        kfree(sc);
+
+        return ret;
+}
+
+/* ------------------------------------------------------------ */
+
+static void o2net_sc_queue_work(struct o2net_sock_container *sc,
+                                struct work_struct *work)
+{
+        sc_get(sc);
+        if (!queue_work(o2net_wq, work))
+                sc_put(sc);
+}
+static void o2net_sc_queue_delayed_work(struct o2net_sock_container *sc,
+                                        struct work_struct *work,
+                                        int delay)
+{
+        sc_get(sc);
+        if (!queue_delayed_work(o2net_wq, work, delay))
+                sc_put(sc);
+}
+static void o2net_sc_cancel_delayed_work(struct o2net_sock_container *sc,
+                                         struct work_struct *work)
+{
+        if (cancel_delayed_work(work))
+                sc_put(sc);
+}
+
+static void o2net_set_nn_state(struct o2net_node *nn,
+                               struct o2net_sock_container *sc,
+                               unsigned valid, int err)
+{
+        int was_valid = nn->nn_sc_valid;
+        int was_err = nn->nn_persistent_error;
+        struct o2net_sock_container *old_sc = nn->nn_sc;
+
+        assert_spin_locked(&nn->nn_lock);
+
+        /* 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);
+
+        /* we won't reconnect after our valid conn goes away for
+         * this hb iteration.. here so it shows up in the logs */
+        if (was_valid && !valid && err == 0)
+                err = -ENOTCONN;
+
+        mlog(ML_CONN, "node %u sc: %p -> %p, valid %u -> %u, err %d -> %d\n",
+             o2net_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 o2net_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) {
+                o2quo_conn_err(o2net_num_from_nn(nn));
+                queue_delayed_work(o2net_wq, &nn->nn_still_up,
+                                   msecs_to_jiffies(O2NET_QUORUM_DELAY_MS));
+        }
+
+        if (was_valid && !valid) {
+                mlog(ML_NOTICE, "no longer connected to " SC_NODEF_FMT "\n",
+                     SC_NODEF_ARGS(old_sc));
+                o2net_complete_nodes_nsw(nn);
+        }
+
+        if (!was_valid && valid) {
+                o2quo_conn_up(o2net_num_from_nn(nn));
+                /* this is a bit of a hack.  we only try reconnecting
+                 * when heartbeating starts until we get a connection.
+                 * if that connection then dies we don't try reconnecting.
+                 * the only way to start connecting again is to down
+                 * heartbeat and bring it back up. */
+                cancel_delayed_work(&nn->nn_connect_expired);
+                mlog(ML_NOTICE, "%s " SC_NODEF_FMT "\n", 
+                     o2nm_this_node() > sc->sc_node->nd_num ?
+                        "connected to" : "accepted connection from",
+                     SC_NODEF_ARGS(sc));
+        }
+
+        /* 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 && o2net_wq) {
+                unsigned long delay;
+                /* delay if we're withing a RECONNECT_DELAY of the
+                 * last attempt */
+                delay = (nn->nn_last_connect_attempt +
+                         msecs_to_jiffies(O2NET_RECONNECT_DELAY_MS))
+                        - jiffies;
+                if (delay > msecs_to_jiffies(O2NET_RECONNECT_DELAY_MS))
+                        delay = 0;
+                mlog(ML_CONN, "queueing conn attempt in %lu jiffies\n", delay);
+                queue_delayed_work(o2net_wq, &nn->nn_connect_work, 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)) {
+                o2net_sc_queue_work(old_sc, &old_sc->sc_shutdown_work);
+                sc_put(old_sc);
+        }
+}
+
+/* see o2net_register_callbacks() */
+static void o2net_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 o2net_sock_container *sc = sk->sk_user_data;
+                sclog(sc, "data_ready hit\n");
+                do_gettimeofday(&sc->sc_tv_data_ready);
+                o2net_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 o2net_register_callbacks() */
+static void o2net_state_change(struct sock *sk)
+{
+        void (*state_change)(struct sock *sk);
+        struct o2net_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:
+                        o2net_sc_queue_work(sc, &sc->sc_connect_work);
+                        break;
+                default:
+                        o2net_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 our careful to test user_data
+ * to discover when they've reaced with o2net_unregister_callbacks().
+ */
+static void o2net_register_callbacks(struct sock *sk,
+                                     struct o2net_sock_container *sc)
+{
+        write_lock_bh(&sk->sk_callback_lock);
+
+        /* accepted sockets inherit the old listen socket data ready */
+        if (sk->sk_data_ready == o2net_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 = o2net_data_ready;
+        sk->sk_state_change = o2net_state_change;
+
+        write_unlock_bh(&sk->sk_callback_lock);
+}
+
+static int o2net_unregister_callbacks(struct sock *sk,
+                                   struct o2net_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 o2net_ensure_shutdown(struct o2net_node *nn,
+                                   struct o2net_sock_container *sc,
+                                   int err)
+{
+        spin_lock(&nn->nn_lock);
+        if (nn->nn_sc == sc)
+                o2net_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 o2net_shutdown_sc(void *arg)
+{
+        struct o2net_sock_container *sc = arg;
+        struct o2net_node *nn = o2net_nn_from_num(sc->sc_node->nd_num);
+
+        sclog(sc, "shutting down\n");
+
+        /* drop the callbacks ref and call shutdown only once */
+        if (o2net_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);
+                o2net_sc_cancel_delayed_work(sc, &sc->sc_keepalive_work);
+                sc_put(sc);
+                sc->sc_sock->ops->shutdown(sc->sc_sock,
+                                           RCV_SHUTDOWN|SEND_SHUTDOWN);
+        }
+
+        /* not fatal so failed connects before the other guy has our
+         * heartbeat can be retried */
+        o2net_ensure_shutdown(nn, sc, 0);
+        sc_put(sc);
+}
+
+/* ------------------------------------------------------------ */
+
+static int o2net_handler_cmp(struct o2net_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 o2net_msg_handler *
+o2net_handler_tree_lookup(u32 msg_type, u32 key, struct rb_node ***ret_p,
+                          struct rb_node **ret_parent)
+{
+        struct rb_node **p = &o2net_handler_tree.rb_node;
+        struct rb_node *parent = NULL;
+        struct o2net_msg_handler *nmh, *ret = NULL;
+        int cmp;
+
+        while (*p) {
+                parent = *p;
+                nmh = rb_entry(parent, struct o2net_msg_handler, nh_node);
+                cmp = o2net_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 o2net_handler_kref_release(struct kref *kref)
+{
+        struct o2net_msg_handler *nmh;
+        nmh = container_of(kref, struct o2net_msg_handler, nh_kref);
+
+        kfree(nmh);
+}
+
+static void o2net_handler_put(struct o2net_msg_handler *nmh)
+{
+        kref_put(&nmh->nh_kref, o2net_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 o2net_register_handler(u32 msg_type, u32 key, u32 max_len,
+                           o2net_msg_handler_func *func, void *data,
+                           struct list_head *unreg_list)
+{
+        struct o2net_msg_handler *nmh = NULL;
+        struct rb_node **p, *parent;
+        int ret = 0;
+
+        if (max_len > O2NET_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 = kcalloc(1, sizeof(struct o2net_msg_handler), GFP_NOFS);
+        if (nmh == NULL) {
+                ret = -ENOMEM;
+                goto out;
+        }
+
+        nmh->nh_func = func;
+        nmh->nh_func_data = data;
+        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(&o2net_handler_lock);
+        if (o2net_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, &o2net_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(o2net_handler_tree_lookup(msg_type, key, &p,
+                                                          &parent) == NULL,
+                                "couldn't find handler we *just* registerd "
+                                "for type %u key %08x\n", msg_type, key);
+        }
+        write_unlock(&o2net_handler_lock);
+        if (ret)
+                goto out;
+
+out:
+        if (ret)
+                kfree(nmh);
+
+        return ret;
+}
+EXPORT_SYMBOL_GPL(o2net_register_handler);
+
+void o2net_unregister_handler_list(struct list_head *list)
+{
+        struct list_head *pos, *n;
+        struct o2net_msg_handler *nmh;
+
+        write_lock(&o2net_handler_lock);
+        list_for_each_safe(pos, n, list) {
+                nmh = list_entry(pos, struct o2net_msg_handler,
+                                 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, &o2net_handler_tree);
+                list_del_init(&nmh->nh_unregister_item);
+                kref_put(&nmh->nh_kref, o2net_handler_kref_release);
+        }
+        write_unlock(&o2net_handler_lock);
+}
+EXPORT_SYMBOL_GPL(o2net_unregister_handler_list);
+
+static struct o2net_msg_handler *o2net_handler_get(u32 msg_type, u32 key)
+{
+        struct o2net_msg_handler *nmh;
+
+        read_lock(&o2net_handler_lock);
+        nmh = o2net_handler_tree_lookup(msg_type, key, NULL, NULL);
+        if (nmh)
+                kref_get(&nmh->nh_kref);
+        read_unlock(&o2net_handler_lock);
+
+        return nmh;
+}
+
+/* ------------------------------------------------------------ */
+
+static int o2net_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 o2net_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 o2net_sendpage(struct o2net_sock_container *sc,
+                           void *kmalloced_virt,
+                           size_t size)
+{
+        struct o2net_node *nn = o2net_nn_from_num(sc->sc_node->nd_num);
+        ssize_t ret;
+
+
+        ret = sc->sc_sock->ops->sendpage(sc->sc_sock,
+                                         virt_to_page(kmalloced_virt),
+                                         (long)kmalloced_virt & ~PAGE_MASK,
+                                         size, MSG_DONTWAIT);
+        if (ret != size) {
+                mlog(ML_ERROR, "sendpage of size %zu to " SC_NODEF_FMT 
+                     " failed with %zd\n", size, SC_NODEF_ARGS(sc), ret);
+                o2net_ensure_shutdown(nn, sc, 0);
+        }
+}
+
+static void o2net_init_msg(struct o2net_msg *msg, u16 data_len, u16 msg_type, u32 key)
+{
+        memset(msg, 0, sizeof(struct o2net_msg));
+        msg->magic = cpu_to_be16(O2NET_MSG_MAGIC);
+        msg->data_len = cpu_to_be16(data_len);
+        msg->msg_type = cpu_to_be16(msg_type);
+        msg->sys_status = cpu_to_be32(O2NET_ERR_NONE);
+        msg->status = 0;
+        msg->key = cpu_to_be32(key);
+}
+
+static int o2net_tx_can_proceed(struct o2net_node *nn,
+                                struct o2net_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;
+}
+
+int o2net_send_message_vec(u32 msg_type, u32 key, struct kvec *caller_vec,
+                           size_t caller_veclen, u8 target_node, int *status)
+{
+        int ret, error = 0;
+        struct o2net_msg *msg = NULL;
+        size_t veclen, caller_bytes = 0;
+        struct kvec *vec = NULL;
+        struct o2net_sock_container *sc = NULL;
+        struct o2net_node *nn = o2net_nn_from_num(target_node);
+        struct o2net_status_wait nsw = {
+                .ns_node_item = LIST_HEAD_INIT(nsw.ns_node_item),
+        };
+
+        if (o2net_wq == NULL) {
+                mlog(0, "attempt to tx without o2netd 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 > O2NET_MAX_PAYLOAD_BYTES) {
+                mlog(0, "total payload len %zu too large\n", caller_bytes);
+                ret = -EINVAL;
+                goto out;
+        }
+
+        if (target_node == o2nm_this_node()) {
+                ret = -ELOOP;
+                goto out;
+        }
+
+        ret = wait_event_interruptible(nn->nn_sc_wq,
+                                       o2net_tx_can_proceed(nn, &sc, &error));
+        if (!ret && error)
+                ret = error;
+        if (ret)
+                goto out;
+
+        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 o2net_msg), GFP_ATOMIC);
+        if (!msg) {
+                mlog(0, "failed to allocate a o2net_msg!\n");
+                ret = -ENOMEM;
+                goto out;
+        }
+
+        o2net_init_msg(msg, caller_bytes, msg_type, key);
+
+        vec[0].iov_len = sizeof(struct o2net_msg);
+        vec[0].iov_base = msg;
+        memcpy(&vec[1], caller_vec, caller_veclen * sizeof(struct kvec));
+
+        ret = o2net_prep_nsw(nn, &nsw);
+        if (ret)
+                goto out;
+
+        msg->msg_num = cpu_to_be32(nsw.ns_id);
+
+        /* finally, convert the message header to network byte-order
+         * and send */
+        ret = o2net_send_tcp_msg(sc->sc_sock, vec, veclen,
+                                 sizeof(struct o2net_msg) + caller_bytes);
+        msglog(msg, "sending returned %d\n", ret);
+        if (ret < 0) {
+                mlog(0, "error returned from o2net_send_tcp_msg=%d\n", ret);
+                goto out;
+        }
+
+        /* wait on other node's handler */
+        wait_event(nsw.ns_wq, o2net_nsw_completed(nn, &nsw));
+
+        /* Note that we avoid overwriting the callers status return
+         * variable if a system error was reported on the other
+         * side. Callers beware. */
+        ret = o2net_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:
+        if (sc)
+                sc_put(sc);
+        if (vec)
+                kfree(vec);
+        if (msg)
+                kfree(msg);
+        o2net_complete_nsw(nn, &nsw, 0, 0, 0);
+        return ret;
+}
+EXPORT_SYMBOL_GPL(o2net_send_message_vec);
+
+int o2net_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 o2net_send_message_vec(msg_type, key, &vec, 1,
+                                      target_node, status);
+}
+EXPORT_SYMBOL_GPL(o2net_send_message);
+
+static int o2net_send_status_magic(struct socket *sock, struct o2net_msg *hdr,
+                                   enum o2net_system_error syserr, int err)
+{
+        struct kvec vec = {
+                .iov_base = hdr,
+                .iov_len = sizeof(struct o2net_msg),
+        };
+
+        BUG_ON(syserr >= O2NET_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(O2NET_MSG_STATUS_MAGIC);  // twiddle the 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 o2net_send_tcp_msg(sock, &vec, 1, sizeof(struct o2net_msg));
+}
+
+/* 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 o2net_process_message(struct o2net_sock_container *sc,
+                                 struct o2net_msg *hdr)
+{
+        struct o2net_node *nn = o2net_nn_from_num(sc->sc_node->nd_num);
+        int ret = 0, handler_status;
+        enum  o2net_system_error syserr;
+        struct o2net_msg_handler *nmh = NULL;
+
+        msglog(hdr, "processing message\n");
+
+        o2net_sc_postpone_idle(sc);
+
+        switch(be16_to_cpu(hdr->magic)) {
+                case O2NET_MSG_STATUS_MAGIC:
+                        /* special type for returning message status */
+                        o2net_complete_nsw(nn, NULL,
+                                           be32_to_cpu(hdr->msg_num),
+                                           be32_to_cpu(hdr->sys_status),
+                                           be32_to_cpu(hdr->status));
+                        goto out;
+                case O2NET_MSG_KEEP_REQ_MAGIC:
+                        o2net_sendpage(sc, o2net_keep_resp,
+                                       sizeof(*o2net_keep_resp));
+                        goto out;
+                case O2NET_MSG_KEEP_RESP_MAGIC:
+                        goto out;
+                case O2NET_MSG_MAGIC:
+                        break;
+                default:
+                        msglog(hdr, "bad magic\n");
+                        ret = -EINVAL;
+                        goto out;
+                        break;
+        }
+
+        /* find a handler for it */
+        handler_status = 0;
+        nmh = o2net_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 = O2NET_ERR_NO_HNDLR;
+                goto out_respond;
+        }
+
+        syserr = O2NET_ERR_NONE;
+
+        if (be16_to_cpu(hdr->data_len) > nmh->nh_max_len)
+                syserr = O2NET_ERR_OVERFLOW;
+
+        if (syserr != O2NET_ERR_NONE)
+                goto out_respond;
+
+        do_gettimeofday(&sc->sc_tv_func_start);
+        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 o2net_msg) +
+                                             be16_to_cpu(hdr->data_len),
+                                        nmh->nh_func_data);
+        do_gettimeofday(&sc->sc_tv_func_stop);
+
+out_respond:
+        /* this destroys the hdr, so don't use it after this */
+        ret = o2net_send_status_magic(sc->sc_sock, hdr, syserr,
+                                      handler_status);
+        hdr = NULL;
+        mlog(0, "sending handler status %d, syserr %d returned %d\n",
+             handler_status, syserr, ret);
+
+out:
+        if (nmh)
+                o2net_handler_put(nmh);
+        return ret;
+}
+
+static int o2net_check_handshake(struct o2net_sock_container *sc)
+{
+        struct o2net_handshake *hand = page_address(sc->sc_page);
+        struct o2net_node *nn = o2net_nn_from_num(sc->sc_node->nd_num);
+
+        if (hand->protocol_version != cpu_to_be64(O2NET_PROTOCOL_VERSION)) {
+                mlog(ML_NOTICE, SC_NODEF_FMT " advertised net protocol "
+                     "version %llu but %llu is required, disconnecting\n",
+                     SC_NODEF_ARGS(sc),
+                     (unsigned long long)be64_to_cpu(hand->protocol_version),
+                     O2NET_PROTOCOL_VERSION);
+
+                /* don't bother reconnecting if its the wrong version. */
+                o2net_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) {
+                o2net_sc_postpone_idle(sc);
+                o2net_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 o2net_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 o2net_advance_rx(struct o2net_sock_container *sc)
+{
+        struct o2net_msg *hdr;
+        int ret = 0;
+        void *data;
+        size_t datalen;
+
+        sclog(sc, "receiving\n");
+        do_gettimeofday(&sc->sc_tv_advance_start);
+
+        /* do we need more header? */
+        if (sc->sc_page_off < sizeof(struct o2net_msg)) {
+                data = page_address(sc->sc_page) + sc->sc_page_off;
+                datalen = sizeof(struct o2net_msg) - sc->sc_page_off;
+                ret = o2net_recv_tcp_msg(sc->sc_sock, data, datalen);
+                if (ret > 0) {
+                        sc->sc_page_off += ret;
+
+                        /* this working relies on the handshake being
+                         * smaller than the normal message header */
+                        if (sc->sc_page_off >= sizeof(struct o2net_handshake)&&
+                            !sc->sc_handshake_ok && o2net_check_handshake(sc)) {
+                                ret = -EPROTO;
+                                goto out;
+                        }
+
+                        /* 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 o2net_msg)) {
+                                hdr = page_address(sc->sc_page);
+                                if (be16_to_cpu(hdr->data_len) >
+                                    O2NET_MAX_PAYLOAD_BYTES)
+                                        ret = -EOVERFLOW;
+                        }
+                }
+                if (ret <= 0)
+                        goto out;
+        }
+
+        if (sc->sc_page_off < sizeof(struct o2net_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 o2net_msg) < be16_to_cpu(hdr->data_len)) {
+                /* need more payload */
+                data = page_address(sc->sc_page) + sc->sc_page_off;
+                datalen = (sizeof(struct o2net_msg) + be16_to_cpu(hdr->data_len)) -
+                          sc->sc_page_off;
+                ret = o2net_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 o2net_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 = o2net_process_message(sc, hdr);
+                if (ret == 0)
+                        ret = 1;
+                sc->sc_page_off = 0;
+        }
+
+out:
+        sclog(sc, "ret = %d\n", ret);
+        do_gettimeofday(&sc->sc_tv_advance_stop);
+        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 o2net_rx_until_empty(void *arg)
+{
+        struct o2net_sock_container *sc = arg;
+        int ret;
+
+        do {
+                ret = o2net_advance_rx(sc);
+        } while (ret > 0);
+
+        if (ret <= 0 && ret != -EAGAIN) {
+                struct o2net_node *nn = o2net_nn_from_num(sc->sc_node->nd_num);
+                sclog(sc, "saw error %d, closing\n", ret);
+                /* not permanent so read failed handshake can retry */
+                o2net_ensure_shutdown(nn, sc, 0);
+        }
+
+        sc_put(sc);
+}
+
+static int o2net_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;
+}
+
+/* ------------------------------------------------------------ */
+
+/* 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 o2net_sc_connect_completed(void *arg)
+{
+        struct o2net_sock_container *sc = arg;
+
+        mlog(ML_MSG, "sc sending handshake with ver %llu id %llx\n",
+              (unsigned long long)O2NET_PROTOCOL_VERSION,
+              (unsigned long long)be64_to_cpu(o2net_hand->connector_id));
+
+        o2net_sendpage(sc, o2net_hand, sizeof(*o2net_hand));
+        sc_put(sc);
+}
+
+/* this is called as a work_struct func. */
+static void o2net_sc_send_keep_req(void *arg)
+{
+        struct o2net_sock_container *sc = arg;
+
+        o2net_sendpage(sc, o2net_keep_req, sizeof(*o2net_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 o2net_idle_timer(unsigned long data)
+{
+        struct o2net_sock_container *sc = (struct o2net_sock_container *)data;
+        struct timeval now;
+
+        do_gettimeofday(&now);
+
+        mlog(ML_NOTICE, "connection to " SC_NODEF_FMT " has been idle for 10 "
+             "seconds, shutting it down.\n", SC_NODEF_ARGS(sc));
+        mlog(ML_NOTICE, "here are some times that might help debug the "
+             "situation: (tmr %ld.%ld now %ld.%ld dr %ld.%ld adv "
+             "%ld.%ld:%ld.%ld func (%08x:%u) %ld.%ld:%ld.%ld)\n",
+             sc->sc_tv_timer.tv_sec, sc->sc_tv_timer.tv_usec, 
+             now.tv_sec, now.tv_usec,
+             sc->sc_tv_data_ready.tv_sec, sc->sc_tv_data_ready.tv_usec, 
+             sc->sc_tv_advance_start.tv_sec, sc->sc_tv_advance_start.tv_usec, 
+             sc->sc_tv_advance_stop.tv_sec, sc->sc_tv_advance_stop.tv_usec, 
+             sc->sc_msg_key, sc->sc_msg_type,
+             sc->sc_tv_func_start.tv_sec, sc->sc_tv_func_start.tv_usec,
+             sc->sc_tv_func_stop.tv_sec, sc->sc_tv_func_stop.tv_usec);
+
+        o2net_sc_queue_work(sc, &sc->sc_shutdown_work);
+}
+
+static void o2net_sc_postpone_idle(struct o2net_sock_container *sc)
+{
+        o2net_sc_cancel_delayed_work(sc, &sc->sc_keepalive_work);
+        o2net_sc_queue_delayed_work(sc, &sc->sc_keepalive_work,
+                                    O2NET_KEEPALIVE_DELAY_SECS * HZ);
+        do_gettimeofday(&sc->sc_tv_timer);
+        mod_timer(&sc->sc_idle_timeout,
+                  jiffies + (O2NET_IDLE_TIMEOUT_SECS * HZ));
+}
+
+/* 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 o2net_start_connect(void *arg)
+{
+        struct o2net_node *nn = arg;
+        struct o2net_sock_container *sc = NULL;
+        struct o2nm_node *node = NULL;
+        struct socket *sock = NULL;
+        struct sockaddr_in myaddr = {0, }, remoteaddr = {0, };
+        int ret = 0;
+
+        /* if we're greater we initiate tx, otherwise we accept */
+        if (o2nm_this_node() <= o2net_num_from_nn(nn))
+                goto out;
+
+        /* watch for racing with tearing a node down */
+        node = o2nm_get_node_by_num(o2net_num_from_nn(nn));
+        if (node == NULL) {
+                ret = 0;
+                goto out;
+        }
+
+        spin_lock(&nn->nn_lock);
+        /* see if we already have one pending or have given up */
+        if (nn->nn_sc || nn->nn_persistent_error)
+                arg = NULL;
+        spin_unlock(&nn->nn_lock);
+        if (arg == NULL) /* *shrug*, needed some indicator */
+                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_port = (__force u16)htons(0); /* any port */
+
+        ret = sock->ops->bind(sock, (struct sockaddr *)&myaddr,
+                              sizeof(myaddr));
+        if (ret) {
+                mlog(0, "bind failed: %d\n", ret);
+                goto out;
+        }
+
+        ret = o2net_set_nodelay(sc->sc_sock);
+        if (ret) {
+                mlog(ML_ERROR, "setting TCP_NODELAY failed with %d\n", ret);
+                goto out;
+        }
+
+        o2net_register_callbacks(sc->sc_sock->sk, sc);
+
+        spin_lock(&nn->nn_lock);
+        /* handshake completion will set nn->nn_sc_valid */
+        o2net_set_nn_state(nn, sc, 0, 0);
+        spin_unlock(&nn->nn_lock);
+
+        remoteaddr.sin_family = AF_INET;
+        remoteaddr.sin_addr.s_addr = (__force u32)node->nd_ipv4_address;
+        remoteaddr.sin_port = (__force u16)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) {
+                mlog(ML_NOTICE, "connect attempt to " SC_NODEF_FMT " failed "
+                     "with errno %d\n", SC_NODEF_ARGS(sc), ret);
+                /* 0 err so that another will be queued and attempted
+                 * from set_nn_state */
+                if (sc)
+                        o2net_ensure_shutdown(nn, sc, 0);
+        }
+        if (sc)
+                sc_put(sc);
+        if (node)
+                o2nm_node_put(node);
+
+        return;
+}
+
+static void o2net_connect_expired(void *arg)
+{
+        struct o2net_node *nn = arg;
+
+        spin_lock(&nn->nn_lock);
+        if (!nn->nn_sc_valid) {
+                mlog(ML_ERROR, "no connection established with node %u after "
+                     "%u seconds, giving up and returning errors.\n",
+                     o2net_num_from_nn(nn), O2NET_IDLE_TIMEOUT_SECS);
+
+                o2net_set_nn_state(nn, NULL, 0, -ENOTCONN);
+        }
+        spin_unlock(&nn->nn_lock);
+}
+
+static void o2net_still_up(void *arg)
+{
+        struct o2net_node *nn = arg;
+
+        o2quo_hb_still_up(o2net_num_from_nn(nn));
+}
+
+/* ------------------------------------------------------------ */
+
+void o2net_disconnect_node(struct o2nm_node *node)
+{
+        struct o2net_node *nn = o2net_nn_from_num(node->nd_num);
+
+        /* don't reconnect until it's heartbeating again */
+        spin_lock(&nn->nn_lock);
+        o2net_set_nn_state(nn, NULL, 0, -ENOTCONN);
+        spin_unlock(&nn->nn_lock);
+
+        if (o2net_wq) {
+                cancel_delayed_work(&nn->nn_connect_expired);
+                cancel_delayed_work(&nn->nn_connect_work);
+                cancel_delayed_work(&nn->nn_still_up);
+                flush_workqueue(o2net_wq);
+        }
+}
+
+static void o2net_hb_node_down_cb(struct o2nm_node *node, int node_num,
+                                  void *data)
+{
+        o2quo_hb_down(node_num);
+
+        if (node_num != o2nm_this_node())
+                o2net_disconnect_node(node);
+}
+
+static void o2net_hb_node_up_cb(struct o2nm_node *node, int node_num,
+                                void *data)
+{
+        struct o2net_node *nn = o2net_nn_from_num(node_num);
+
+        o2quo_hb_up(node_num);
+
+        /* ensure an immediate connect attempt */
+        nn->nn_last_connect_attempt = jiffies -
+                (msecs_to_jiffies(O2NET_RECONNECT_DELAY_MS) + 1);
+
+        if (node_num != o2nm_this_node()) {
+                /* heartbeat doesn't work unless a local node number is
+                 * configured and doing so brings up the o2net_wq, so we can
+                 * use it.. */
+                queue_delayed_work(o2net_wq, &nn->nn_connect_expired,
+                                   O2NET_IDLE_TIMEOUT_SECS * HZ);
+
+                /* 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);
+                if (nn->nn_persistent_error)
+                        o2net_set_nn_state(nn, NULL, 0, 0);
+                spin_unlock(&nn->nn_lock);
+        }
+}
+
+void o2net_unregister_hb_callbacks(void)
+{
+        int ret;
+
+        ret = o2hb_unregister_callback(&o2net_hb_up);
+        if (ret < 0)
+                mlog(ML_ERROR, "Status return %d unregistering heartbeat up "
+                     "callback!\n", ret);
+
+        ret = o2hb_unregister_callback(&o2net_hb_down);
+        if (ret < 0)
+                mlog(ML_ERROR, "Status return %d unregistering heartbeat down "
+                     "callback!\n", ret);
+}
+
+int o2net_register_hb_callbacks(void)
+{
+        int ret;
+
+        o2hb_setup_callback(&o2net_hb_down, O2HB_NODE_DOWN_CB,
+                            o2net_hb_node_down_cb, NULL, O2NET_HB_PRI);
+        o2hb_setup_callback(&o2net_hb_up, O2HB_NODE_UP_CB,
+                            o2net_hb_node_up_cb, NULL, O2NET_HB_PRI);
+
+        ret = o2hb_register_callback(&o2net_hb_up);
+        if (ret == 0)
+                ret = o2hb_register_callback(&o2net_hb_down);
+
+        if (ret)
+                o2net_unregister_hb_callbacks();
+
+        return ret;
+}
+
+/* ------------------------------------------------------------ */
+
+static int o2net_accept_one(struct socket *sock)
+{
+        int ret, slen;
+        struct sockaddr_in sin;
+        struct socket *new_sock = NULL;
+        struct o2nm_node *node = NULL;
+        struct o2net_sock_container *sc = NULL;
+        struct o2net_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 = o2net_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 = o2nm_get_node_by_ip((__force __be32)sin.sin_addr.s_addr);
+        if (node == NULL) {
+                mlog(ML_NOTICE, "attempt to connect from unknown node at "
+                     "%u.%u.%u.%u:%d\n", NIPQUAD(sin.sin_addr.s_addr),
+                     ntohs((__force __be16)sin.sin_port));
+                ret = -EINVAL;
+                goto out;
+        }
+
+        if (o2nm_this_node() > node->nd_num) {
+                mlog(ML_NOTICE, "unexpected connect attempted from a lower "
+                     "numbered node '%s' at " "%u.%u.%u.%u:%d with num %u\n",
+                     node->nd_name, NIPQUAD(sin.sin_addr.s_addr),
+                     ntohs((__force __be16)sin.sin_port), node->nd_num);
+                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 (!o2hb_check_node_heartbeating_from_callback(node->nd_num)) {
+                mlog(ML_CONN, "attempt to connect from node '%s' at "
+                     "%u.%u.%u.%u:%d but it isn't heartbeating\n",
+                     node->nd_name, NIPQUAD(sin.sin_addr.s_addr),
+                     ntohs((__force __be16)sin.sin_port));
+                ret = -EINVAL;
+                goto out;
+        }
+
+        nn = o2net_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) {
+                mlog(ML_NOTICE, "attempt to connect from node '%s' at "
+                     "%u.%u.%u.%u:%d but it already has an open connection\n",
+                     node->nd_name, NIPQUAD(sin.sin_addr.s_addr),
+                     ntohs((__force __be16)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);
+        o2net_set_nn_state(nn, sc, 0, 0);
+        spin_unlock(&nn->nn_lock);
+
+        o2net_register_callbacks(sc->sc_sock->sk, sc);
+        o2net_sc_queue_work(sc, &sc->sc_rx_work);
+
+        o2net_sendpage(sc, o2net_hand, sizeof(*o2net_hand));
+
+out:
+        if (new_sock)
+                sock_release(new_sock);
+        if (node)
+                o2nm_node_put(node);
+        if (sc)
+                sc_put(sc);
+        return ret;
+}
+
+static void o2net_accept_many(void *arg)
+{
+        struct socket *sock = arg;
+        while (o2net_accept_one(sock) == 0)
+                cond_resched();
+}
+
+static void o2net_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(o2net_wq, &o2net_listen_work);
+        }
+
+out:
+        read_unlock(&sk->sk_callback_lock);
+        ready(sk, bytes);
+}
+
+static int o2net_open_listening_sock(__be16 port)
+{
+        struct socket *sock = NULL;
+        int ret;
+        struct sockaddr_in sin = {
+                .sin_family = PF_INET,
+                .sin_addr = { .s_addr = (__force u32)htonl(INADDR_ANY) },
+                .sin_port = (__force u16)port,
+        };
+
+        ret = sock_create(PF_INET, SOCK_STREAM, IPPROTO_TCP, &sock);
+        if (ret < 0) {
+                mlog(ML_ERROR, "unable to create socket, ret=%d\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 = o2net_listen_data_ready;
+        write_unlock_bh(&sock->sk->sk_callback_lock);
+
+        o2net_listen_sock = sock;
+        INIT_WORK(&o2net_listen_work, o2net_accept_many, sock);
+
+        sock->sk->sk_reuse = 1;
+        ret = sock->ops->bind(sock, (struct sockaddr *)&sin, sizeof(sin));
+        if (ret < 0) {
+                mlog(ML_ERROR, "unable to bind socket to port %d, ret=%d\n",
+                     ntohs(port), ret);
+                goto out;
+        }
+
+        ret = sock->ops->listen(sock, 64);
+        if (ret < 0) {
+                mlog(ML_ERROR, "unable to listen on port %d, ret=%d\n",
+                     ntohs(port), ret);
+        }
+
+out:
+        if (ret) {
+                o2net_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 o2net_stop_listening().  note,
+ * o2nm_this_node() doesn't work yet as we're being called while it
+ * is being set up.
+ */
+int o2net_start_listening(struct o2nm_node *node)
+{
+        int ret = 0;
+
+        BUG_ON(o2net_wq != NULL);
+        BUG_ON(o2net_listen_sock != NULL);
+
+        mlog(ML_KTHREAD, "starting o2net thread...\n");
+        o2net_wq = create_singlethread_workqueue("o2net");
+        if (o2net_wq == NULL) {
+                mlog(ML_ERROR, "unable to launch o2net thread\n");
+                return -ENOMEM; /* ? */
+        }
+
+        ret = o2net_open_listening_sock(node->nd_ipv4_port);
+        if (ret) {
+                destroy_workqueue(o2net_wq);
+                o2net_wq = NULL;
+        } else
+                o2quo_conn_up(node->nd_num);
+
+        return ret;
+}
+
+/* again, o2nm_this_node() doesn't work here as we're involved in
+ * tearing it down */
+void o2net_stop_listening(struct o2nm_node *node)
+{
+        struct socket *sock = o2net_listen_sock;
+        size_t i;
+
+        BUG_ON(o2net_wq == NULL);
+        BUG_ON(o2net_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(o2net_nodes); i++) {
+                struct o2nm_node *node = o2nm_get_node_by_num(i);
+                if (node) {
+                        o2net_disconnect_node(node);
+                        o2nm_node_put(node);
+                }
+        }
+
+        /* finish all work and tear down the work queue */
+        mlog(ML_KTHREAD, "waiting for o2net thread to exit....\n");
+        destroy_workqueue(o2net_wq);
+        o2net_wq = NULL;
+
+        sock_release(o2net_listen_sock);
+        o2net_listen_sock = NULL;
+
+        o2quo_conn_err(node->nd_num);
+}
+
+/* ------------------------------------------------------------ */
+
+int o2net_init(void)
+{
+        unsigned long i;
+
+        o2quo_init();
+
+        o2net_hand = kcalloc(1, sizeof(struct o2net_handshake), GFP_KERNEL);
+        o2net_keep_req = kcalloc(1, sizeof(struct o2net_msg), GFP_KERNEL);
+        o2net_keep_resp = kcalloc(1, sizeof(struct o2net_msg), GFP_KERNEL);
+        if (!o2net_hand || !o2net_keep_req || !o2net_keep_resp) {
+                kfree(o2net_hand);
+                kfree(o2net_keep_req);
+                kfree(o2net_keep_resp);
+                return -ENOMEM;
+        }
+
+        o2net_hand->protocol_version = cpu_to_be64(O2NET_PROTOCOL_VERSION);
+        o2net_hand->connector_id = cpu_to_be64(1);
+
+        o2net_keep_req->magic = cpu_to_be16(O2NET_MSG_KEEP_REQ_MAGIC);
+        o2net_keep_resp->magic = cpu_to_be16(O2NET_MSG_KEEP_RESP_MAGIC);
+
+        for (i = 0; i < ARRAY_SIZE(o2net_nodes); i++) {
+                struct o2net_node *nn = o2net_nn_from_num(i);
+
+                spin_lock_init(&nn->nn_lock);
+                INIT_WORK(&nn->nn_connect_work, o2net_start_connect, nn);
+                INIT_WORK(&nn->nn_connect_expired, o2net_connect_expired, nn);
+                INIT_WORK(&nn->nn_still_up, o2net_still_up, nn);
+                /* 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 o2net_exit(void)
+{
+        o2quo_exit();
+        kfree(o2net_hand);
+        kfree(o2net_keep_req);
+        kfree(o2net_keep_resp);
+}