[PATCH] OCFS2: The Second Oracle Cluster Filesystem

A distributed lock manager built with the cluster file system use case
in mind. The OCFS2 dlm exposes a VMS style API, though things have
been simplified internally. The only lock levels implemented currently
are NLMODE, PRMODE and EXMODE.

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

1 files changed, 1469 insertions, 0 deletions

diff --git a/fs/ocfs2/dlm/dlmdomain.c b/fs/ocfs2/dlm/dlmdomain.c
new file mode 100644
index 000000000000..da3c22045f89
--- /dev/null
+++ b/fs/ocfs2/dlm/dlmdomain.c
@@ -0,0 +1,1469 @@
+/* -*- mode: c; c-basic-offset: 8; -*-
+ * vim: noexpandtab sw=8 ts=8 sts=0:
+ *
+ * dlmdomain.c
+ *
+ * defines domain join / leave apis
+ *
+ * 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.
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/highmem.h>
+#include <linux/utsname.h>
+#include <linux/init.h>
+#include <linux/spinlock.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+
+#include "cluster/heartbeat.h"
+#include "cluster/nodemanager.h"
+#include "cluster/tcp.h"
+
+#include "dlmapi.h"
+#include "dlmcommon.h"
+
+#include "dlmdebug.h"
+#include "dlmdomain.h"
+
+#include "dlmver.h"
+
+#define MLOG_MASK_PREFIX (ML_DLM|ML_DLM_DOMAIN)
+#include "cluster/masklog.h"
+
+/*
+ *
+ * spinlock lock ordering: if multiple locks are needed, obey this ordering:
+ *    dlm_domain_lock
+ *    struct dlm_ctxt->spinlock
+ *    struct dlm_lock_resource->spinlock
+ *    struct dlm_ctxt->master_lock
+ *    struct dlm_ctxt->ast_lock
+ *    dlm_master_list_entry->spinlock
+ *    dlm_lock->spinlock
+ *
+ */
+
+spinlock_t dlm_domain_lock = SPIN_LOCK_UNLOCKED;
+LIST_HEAD(dlm_domains);
+static DECLARE_WAIT_QUEUE_HEAD(dlm_domain_events);
+
+#define DLM_DOMAIN_BACKOFF_MS 200
+
+static int dlm_query_join_handler(struct o2net_msg *msg, u32 len, void *data);
+static int dlm_assert_joined_handler(struct o2net_msg *msg, u32 len, void *data);
+static int dlm_cancel_join_handler(struct o2net_msg *msg, u32 len, void *data);
+static int dlm_exit_domain_handler(struct o2net_msg *msg, u32 len, void *data);
+
+static void dlm_unregister_domain_handlers(struct dlm_ctxt *dlm);
+
+void __dlm_unhash_lockres(struct dlm_lock_resource *lockres)
+{
+        list_del_init(&lockres->list);
+        dlm_lockres_put(lockres);
+}
+
+void __dlm_insert_lockres(struct dlm_ctxt *dlm,
+                       struct dlm_lock_resource *res)
+{
+        struct list_head *bucket;
+        struct qstr *q;
+
+        assert_spin_locked(&dlm->spinlock);
+
+        q = &res->lockname;
+        q->hash = full_name_hash(q->name, q->len);
+        bucket = &(dlm->resources[q->hash & DLM_HASH_MASK]);
+
+        /* get a reference for our hashtable */
+        dlm_lockres_get(res);
+
+        list_add_tail(&res->list, bucket);
+}
+
+struct dlm_lock_resource * __dlm_lookup_lockres(struct dlm_ctxt *dlm,
+                                         const char *name,
+                                         unsigned int len)
+{
+        unsigned int hash;
+        struct list_head *iter;
+        struct dlm_lock_resource *tmpres=NULL;
+        struct list_head *bucket;
+
+        mlog_entry("%.*s\n", len, name);
+
+        assert_spin_locked(&dlm->spinlock);
+
+        hash = full_name_hash(name, len);
+
+        bucket = &(dlm->resources[hash & DLM_HASH_MASK]);
+
+        /* check for pre-existing lock */
+        list_for_each(iter, bucket) {
+                tmpres = list_entry(iter, struct dlm_lock_resource, list);
+                if (tmpres->lockname.len == len &&
+                    memcmp(tmpres->lockname.name, name, len) == 0) {
+                        dlm_lockres_get(tmpres);
+                        break;
+                }
+
+                tmpres = NULL;
+        }
+        return tmpres;
+}
+
+struct dlm_lock_resource * dlm_lookup_lockres(struct dlm_ctxt *dlm,
+                                    const char *name,
+                                    unsigned int len)
+{
+        struct dlm_lock_resource *res;
+
+        spin_lock(&dlm->spinlock);
+        res = __dlm_lookup_lockres(dlm, name, len);
+        spin_unlock(&dlm->spinlock);
+        return res;
+}
+
+static struct dlm_ctxt * __dlm_lookup_domain_full(const char *domain, int len)
+{
+        struct dlm_ctxt *tmp = NULL;
+        struct list_head *iter;
+
+        assert_spin_locked(&dlm_domain_lock);
+
+        /* tmp->name here is always NULL terminated,
+         * but domain may not be! */
+        list_for_each(iter, &dlm_domains) {
+                tmp = list_entry (iter, struct dlm_ctxt, list);
+                if (strlen(tmp->name) == len &&
+                    memcmp(tmp->name, domain, len)==0)
+                        break;
+                tmp = NULL;
+        }
+
+        return tmp;
+}
+
+/* For null terminated domain strings ONLY */
+static struct dlm_ctxt * __dlm_lookup_domain(const char *domain)
+{
+        assert_spin_locked(&dlm_domain_lock);
+
+        return __dlm_lookup_domain_full(domain, strlen(domain));
+}
+
+
+/* returns true on one of two conditions:
+ * 1) the domain does not exist
+ * 2) the domain exists and it's state is "joined" */
+static int dlm_wait_on_domain_helper(const char *domain)
+{
+        int ret = 0;
+        struct dlm_ctxt *tmp = NULL;
+
+        spin_lock(&dlm_domain_lock);
+
+        tmp = __dlm_lookup_domain(domain);
+        if (!tmp)
+                ret = 1;
+        else if (tmp->dlm_state == DLM_CTXT_JOINED)
+                ret = 1;
+
+        spin_unlock(&dlm_domain_lock);
+        return ret;
+}
+
+static void dlm_free_ctxt_mem(struct dlm_ctxt *dlm)
+{
+        if (dlm->resources)
+                free_page((unsigned long) dlm->resources);
+
+        if (dlm->name)
+                kfree(dlm->name);
+
+        kfree(dlm);
+}
+
+/* A little strange - this function will be called while holding
+ * dlm_domain_lock and is expected to be holding it on the way out. We
+ * will however drop and reacquire it multiple times */
+static void dlm_ctxt_release(struct kref *kref)
+{
+        struct dlm_ctxt *dlm;
+
+        dlm = container_of(kref, struct dlm_ctxt, dlm_refs);
+
+        BUG_ON(dlm->num_joins);
+        BUG_ON(dlm->dlm_state == DLM_CTXT_JOINED);
+
+        /* we may still be in the list if we hit an error during join. */
+        list_del_init(&dlm->list);
+
+        spin_unlock(&dlm_domain_lock);
+
+        mlog(0, "freeing memory from domain %s\n", dlm->name);
+
+        wake_up(&dlm_domain_events);
+
+        dlm_free_ctxt_mem(dlm);
+
+        spin_lock(&dlm_domain_lock);
+}
+
+void dlm_put(struct dlm_ctxt *dlm)
+{
+        spin_lock(&dlm_domain_lock);
+        kref_put(&dlm->dlm_refs, dlm_ctxt_release);
+        spin_unlock(&dlm_domain_lock);
+}
+
+static void __dlm_get(struct dlm_ctxt *dlm)
+{
+        kref_get(&dlm->dlm_refs);
+}
+
+/* given a questionable reference to a dlm object, gets a reference if
+ * it can find it in the list, otherwise returns NULL in which case
+ * you shouldn't trust your pointer. */
+struct dlm_ctxt *dlm_grab(struct dlm_ctxt *dlm)
+{
+        struct list_head *iter;
+        struct dlm_ctxt *target = NULL;
+
+        spin_lock(&dlm_domain_lock);
+
+        list_for_each(iter, &dlm_domains) {
+                target = list_entry (iter, struct dlm_ctxt, list);
+
+                if (target == dlm) {
+                        __dlm_get(target);
+                        break;
+                }
+
+                target = NULL;
+        }
+
+        spin_unlock(&dlm_domain_lock);
+
+        return target;
+}
+
+int dlm_domain_fully_joined(struct dlm_ctxt *dlm)
+{
+        int ret;
+
+        spin_lock(&dlm_domain_lock);
+        ret = (dlm->dlm_state == DLM_CTXT_JOINED) ||
+                (dlm->dlm_state == DLM_CTXT_IN_SHUTDOWN);
+        spin_unlock(&dlm_domain_lock);
+
+        return ret;
+}
+
+static void dlm_complete_dlm_shutdown(struct dlm_ctxt *dlm)
+{
+        dlm_unregister_domain_handlers(dlm);
+        dlm_complete_thread(dlm);
+        dlm_complete_recovery_thread(dlm);
+
+        /* We've left the domain. Now we can take ourselves out of the
+         * list and allow the kref stuff to help us free the
+         * memory. */
+        spin_lock(&dlm_domain_lock);
+        list_del_init(&dlm->list);
+        spin_unlock(&dlm_domain_lock);
+
+        /* Wake up anyone waiting for us to remove this domain */
+        wake_up(&dlm_domain_events);
+}
+
+static void dlm_migrate_all_locks(struct dlm_ctxt *dlm)
+{
+        int i;
+        struct dlm_lock_resource *res;
+
+        mlog(0, "Migrating locks from domain %s\n", dlm->name);
+restart:
+        spin_lock(&dlm->spinlock);
+        for (i=0; i<DLM_HASH_SIZE; i++) {
+                while (!list_empty(&dlm->resources[i])) {
+                        res = list_entry(dlm->resources[i].next,
+                                     struct dlm_lock_resource, list);
+                        /* need reference when manually grabbing lockres */
+                        dlm_lockres_get(res);
+                        /* this should unhash the lockres
+                         * and exit with dlm->spinlock */
+                        mlog(0, "purging res=%p\n", res);
+                        if (dlm_lockres_is_dirty(dlm, res)) {
+                                /* HACK!  this should absolutely go.
+                                 * need to figure out why some empty
+                                 * lockreses are still marked dirty */
+                                mlog(ML_ERROR, "lockres %.*s dirty!\n",
+                                     res->lockname.len, res->lockname.name);
+
+                                spin_unlock(&dlm->spinlock);
+                                dlm_kick_thread(dlm, res);
+                                wait_event(dlm->ast_wq, !dlm_lockres_is_dirty(dlm, res));
+                                dlm_lockres_put(res);
+                                goto restart;
+                        }
+                        dlm_purge_lockres(dlm, res);
+                        dlm_lockres_put(res);
+                }
+        }
+        spin_unlock(&dlm->spinlock);
+
+        mlog(0, "DONE Migrating locks from domain %s\n", dlm->name);
+}
+
+static int dlm_no_joining_node(struct dlm_ctxt *dlm)
+{
+        int ret;
+
+        spin_lock(&dlm->spinlock);
+        ret = dlm->joining_node == DLM_LOCK_RES_OWNER_UNKNOWN;
+        spin_unlock(&dlm->spinlock);
+
+        return ret;
+}
+
+static void dlm_mark_domain_leaving(struct dlm_ctxt *dlm)
+{
+        /* Yikes, a double spinlock! I need domain_lock for the dlm
+         * state and the dlm spinlock for join state... Sorry! */
+again:
+        spin_lock(&dlm_domain_lock);
+        spin_lock(&dlm->spinlock);
+
+        if (dlm->joining_node != DLM_LOCK_RES_OWNER_UNKNOWN) {
+                mlog(0, "Node %d is joining, we wait on it.\n",
+                          dlm->joining_node);
+                spin_unlock(&dlm->spinlock);
+                spin_unlock(&dlm_domain_lock);
+
+                wait_event(dlm->dlm_join_events, dlm_no_joining_node(dlm));
+                goto again;
+        }
+
+        dlm->dlm_state = DLM_CTXT_LEAVING;
+        spin_unlock(&dlm->spinlock);
+        spin_unlock(&dlm_domain_lock);
+}
+
+static void __dlm_print_nodes(struct dlm_ctxt *dlm)
+{
+        int node = -1;
+
+        assert_spin_locked(&dlm->spinlock);
+
+        mlog(ML_NOTICE, "Nodes in my domain (\"%s\"):\n", dlm->name);
+
+        while ((node = find_next_bit(dlm->domain_map, O2NM_MAX_NODES,
+                                     node + 1)) < O2NM_MAX_NODES) {
+                mlog(ML_NOTICE, " node %d\n", node);
+        }
+}
+
+static int dlm_exit_domain_handler(struct o2net_msg *msg, u32 len, void *data)
+{
+        struct dlm_ctxt *dlm = data;
+        unsigned int node;
+        struct dlm_exit_domain *exit_msg = (struct dlm_exit_domain *) msg->buf;
+
+        mlog_entry("%p %u %p", msg, len, data);
+
+        if (!dlm_grab(dlm))
+                return 0;
+
+        node = exit_msg->node_idx;
+
+        mlog(0, "Node %u leaves domain %s\n", node, dlm->name);
+
+        spin_lock(&dlm->spinlock);
+        clear_bit(node, dlm->domain_map);
+        __dlm_print_nodes(dlm);
+
+        /* notify anything attached to the heartbeat events */
+        dlm_hb_event_notify_attached(dlm, node, 0);
+
+        spin_unlock(&dlm->spinlock);
+
+        dlm_put(dlm);
+
+        return 0;
+}
+
+static int dlm_send_one_domain_exit(struct dlm_ctxt *dlm,
+                                    unsigned int node)
+{
+        int status;
+        struct dlm_exit_domain leave_msg;
+
+        mlog(0, "Asking node %u if we can leave the domain %s me = %u\n",
+                  node, dlm->name, dlm->node_num);
+
+        memset(&leave_msg, 0, sizeof(leave_msg));
+        leave_msg.node_idx = dlm->node_num;
+
+        status = o2net_send_message(DLM_EXIT_DOMAIN_MSG, dlm->key,
+                                    &leave_msg, sizeof(leave_msg), node,
+                                    NULL);
+
+        mlog(0, "status return %d from o2net_send_message\n", status);
+
+        return status;
+}
+
+
+static void dlm_leave_domain(struct dlm_ctxt *dlm)
+{
+        int node, clear_node, status;
+
+        /* At this point we've migrated away all our locks and won't
+         * accept mastership of new ones. The dlm is responsible for
+         * almost nothing now. We make sure not to confuse any joining
+         * nodes and then commence shutdown procedure. */
+
+        spin_lock(&dlm->spinlock);
+        /* Clear ourselves from the domain map */
+        clear_bit(dlm->node_num, dlm->domain_map);
+        while ((node = find_next_bit(dlm->domain_map, O2NM_MAX_NODES,
+                                     0)) < O2NM_MAX_NODES) {
+                /* Drop the dlm spinlock. This is safe wrt the domain_map.
+                 * -nodes cannot be added now as the
+                 *   query_join_handlers knows to respond with OK_NO_MAP
+                 * -we catch the right network errors if a node is
+                 *   removed from the map while we're sending him the
+                 *   exit message. */
+                spin_unlock(&dlm->spinlock);
+
+                clear_node = 1;
+
+                status = dlm_send_one_domain_exit(dlm, node);
+                if (status < 0 &&
+                    status != -ENOPROTOOPT &&
+                    status != -ENOTCONN) {
+                        mlog(ML_NOTICE, "Error %d sending domain exit message "
+                             "to node %d\n", status, node);
+
+                        /* Not sure what to do here but lets sleep for
+                         * a bit in case this was a transient
+                         * error... */
+                        msleep(DLM_DOMAIN_BACKOFF_MS);
+                        clear_node = 0;
+                }
+
+                spin_lock(&dlm->spinlock);
+                /* If we're not clearing the node bit then we intend
+                 * to loop back around to try again. */
+                if (clear_node)
+                        clear_bit(node, dlm->domain_map);
+        }
+        spin_unlock(&dlm->spinlock);
+}
+
+int dlm_joined(struct dlm_ctxt *dlm)
+{
+        int ret = 0;
+
+        spin_lock(&dlm_domain_lock);
+
+        if (dlm->dlm_state == DLM_CTXT_JOINED)
+                ret = 1;
+
+        spin_unlock(&dlm_domain_lock);
+
+        return ret;
+}
+
+int dlm_shutting_down(struct dlm_ctxt *dlm)
+{
+        int ret = 0;
+
+        spin_lock(&dlm_domain_lock);
+
+        if (dlm->dlm_state == DLM_CTXT_IN_SHUTDOWN)
+                ret = 1;
+
+        spin_unlock(&dlm_domain_lock);
+
+        return ret;
+}
+
+void dlm_unregister_domain(struct dlm_ctxt *dlm)
+{
+        int leave = 0;
+
+        spin_lock(&dlm_domain_lock);
+        BUG_ON(dlm->dlm_state != DLM_CTXT_JOINED);
+        BUG_ON(!dlm->num_joins);
+
+        dlm->num_joins--;
+        if (!dlm->num_joins) {
+                /* We mark it "in shutdown" now so new register
+                 * requests wait until we've completely left the
+                 * domain. Don't use DLM_CTXT_LEAVING yet as we still
+                 * want new domain joins to communicate with us at
+                 * least until we've completed migration of our
+                 * resources. */
+                dlm->dlm_state = DLM_CTXT_IN_SHUTDOWN;
+                leave = 1;
+        }
+        spin_unlock(&dlm_domain_lock);
+
+        if (leave) {
+                mlog(0, "shutting down domain %s\n", dlm->name);
+
+                /* We changed dlm state, notify the thread */
+                dlm_kick_thread(dlm, NULL);
+
+                dlm_migrate_all_locks(dlm);
+                dlm_mark_domain_leaving(dlm);
+                dlm_leave_domain(dlm);
+                dlm_complete_dlm_shutdown(dlm);
+        }
+        dlm_put(dlm);
+}
+EXPORT_SYMBOL_GPL(dlm_unregister_domain);
+
+static int dlm_query_join_handler(struct o2net_msg *msg, u32 len, void *data)
+{
+        struct dlm_query_join_request *query;
+        enum dlm_query_join_response response;
+        struct dlm_ctxt *dlm = NULL;
+
+        query = (struct dlm_query_join_request *) msg->buf;
+
+        mlog(0, "node %u wants to join domain %s\n", query->node_idx,
+                  query->domain);
+
+        /*
+         * If heartbeat doesn't consider the node live, tell it
+         * to back off and try again.  This gives heartbeat a chance
+         * to catch up.
+         */
+        if (!o2hb_check_node_heartbeating(query->node_idx)) {
+                mlog(0, "node %u is not in our live map yet\n",
+                     query->node_idx);
+
+                response = JOIN_DISALLOW;
+                goto respond;
+        }
+
+        response = JOIN_OK_NO_MAP;
+
+        spin_lock(&dlm_domain_lock);
+        dlm = __dlm_lookup_domain_full(query->domain, query->name_len);
+        /* Once the dlm ctxt is marked as leaving then we don't want
+         * to be put in someone's domain map. */
+        if (dlm && dlm->dlm_state != DLM_CTXT_LEAVING) {
+                spin_lock(&dlm->spinlock);
+
+                if (dlm->dlm_state == DLM_CTXT_NEW &&
+                    dlm->joining_node == DLM_LOCK_RES_OWNER_UNKNOWN) {
+                        /*If this is a brand new context and we
+                         * haven't started our join process yet, then
+                         * the other node won the race. */
+                        response = JOIN_OK_NO_MAP;
+                } else if (dlm->joining_node != DLM_LOCK_RES_OWNER_UNKNOWN) {
+                        /* Disallow parallel joins. */
+                        response = JOIN_DISALLOW;
+                } else {
+                        /* Alright we're fully a part of this domain
+                         * so we keep some state as to who's joining
+                         * and indicate to him that needs to be fixed
+                         * up. */
+                        response = JOIN_OK;
+                        __dlm_set_joining_node(dlm, query->node_idx);
+                }
+
+                spin_unlock(&dlm->spinlock);
+        }
+        spin_unlock(&dlm_domain_lock);
+
+respond:
+        mlog(0, "We respond with %u\n", response);
+
+        return response;
+}
+
+static int dlm_assert_joined_handler(struct o2net_msg *msg, u32 len, void *data)
+{
+        struct dlm_assert_joined *assert;
+        struct dlm_ctxt *dlm = NULL;
+
+        assert = (struct dlm_assert_joined *) msg->buf;
+
+        mlog(0, "node %u asserts join on domain %s\n", assert->node_idx,
+                  assert->domain);
+
+        spin_lock(&dlm_domain_lock);
+        dlm = __dlm_lookup_domain_full(assert->domain, assert->name_len);
+        /* XXX should we consider no dlm ctxt an error? */
+        if (dlm) {
+                spin_lock(&dlm->spinlock);
+
+                /* Alright, this node has officially joined our
+                 * domain. Set him in the map and clean up our
+                 * leftover join state. */
+                BUG_ON(dlm->joining_node != assert->node_idx);
+                set_bit(assert->node_idx, dlm->domain_map);
+                __dlm_set_joining_node(dlm, DLM_LOCK_RES_OWNER_UNKNOWN);
+
+                __dlm_print_nodes(dlm);
+
+                /* notify anything attached to the heartbeat events */
+                dlm_hb_event_notify_attached(dlm, assert->node_idx, 1);
+
+                spin_unlock(&dlm->spinlock);
+        }
+        spin_unlock(&dlm_domain_lock);
+
+        return 0;
+}
+
+static int dlm_cancel_join_handler(struct o2net_msg *msg, u32 len, void *data)
+{
+        struct dlm_cancel_join *cancel;
+        struct dlm_ctxt *dlm = NULL;
+
+        cancel = (struct dlm_cancel_join *) msg->buf;
+
+        mlog(0, "node %u cancels join on domain %s\n", cancel->node_idx,
+                  cancel->domain);
+
+        spin_lock(&dlm_domain_lock);
+        dlm = __dlm_lookup_domain_full(cancel->domain, cancel->name_len);
+
+        if (dlm) {
+                spin_lock(&dlm->spinlock);
+
+                /* Yikes, this guy wants to cancel his join. No
+                 * problem, we simply cleanup our join state. */
+                BUG_ON(dlm->joining_node != cancel->node_idx);
+                __dlm_set_joining_node(dlm, DLM_LOCK_RES_OWNER_UNKNOWN);
+
+                spin_unlock(&dlm->spinlock);
+        }
+        spin_unlock(&dlm_domain_lock);
+
+        return 0;
+}
+
+static int dlm_send_one_join_cancel(struct dlm_ctxt *dlm,
+                                    unsigned int node)
+{
+        int status;
+        struct dlm_cancel_join cancel_msg;
+
+        memset(&cancel_msg, 0, sizeof(cancel_msg));
+        cancel_msg.node_idx = dlm->node_num;
+        cancel_msg.name_len = strlen(dlm->name);
+        memcpy(cancel_msg.domain, dlm->name, cancel_msg.name_len);
+
+        status = o2net_send_message(DLM_CANCEL_JOIN_MSG, DLM_MOD_KEY,
+                                    &cancel_msg, sizeof(cancel_msg), node,
+                                    NULL);
+        if (status < 0) {
+                mlog_errno(status);
+                goto bail;
+        }
+
+bail:
+        return status;
+}
+
+/* map_size should be in bytes. */
+static int dlm_send_join_cancels(struct dlm_ctxt *dlm,
+                                 unsigned long *node_map,
+                                 unsigned int map_size)
+{
+        int status, tmpstat;
+        unsigned int node;
+
+        if (map_size != (BITS_TO_LONGS(O2NM_MAX_NODES) *
+                         sizeof(unsigned long))) {
+                mlog(ML_ERROR,
+                     "map_size %u != BITS_TO_LONGS(O2NM_MAX_NODES) %u\n",
+                     map_size, BITS_TO_LONGS(O2NM_MAX_NODES));
+                return -EINVAL;
+        }
+
+        status = 0;
+        node = -1;
+        while ((node = find_next_bit(node_map, O2NM_MAX_NODES,
+                                     node + 1)) < O2NM_MAX_NODES) {
+                if (node == dlm->node_num)
+                        continue;
+
+                tmpstat = dlm_send_one_join_cancel(dlm, node);
+                if (tmpstat) {
+                        mlog(ML_ERROR, "Error return %d cancelling join on "
+                             "node %d\n", tmpstat, node);
+                        if (!status)
+                                status = tmpstat;
+                }
+        }
+
+        if (status)
+                mlog_errno(status);
+        return status;
+}
+
+static int dlm_request_join(struct dlm_ctxt *dlm,
+                            int node,
+                            enum dlm_query_join_response *response)
+{
+        int status, retval;
+        struct dlm_query_join_request join_msg;
+
+        mlog(0, "querying node %d\n", node);
+
+        memset(&join_msg, 0, sizeof(join_msg));
+        join_msg.node_idx = dlm->node_num;
+        join_msg.name_len = strlen(dlm->name);
+        memcpy(join_msg.domain, dlm->name, join_msg.name_len);
+
+        status = o2net_send_message(DLM_QUERY_JOIN_MSG, DLM_MOD_KEY, &join_msg,
+                                    sizeof(join_msg), node, &retval);
+        if (status < 0 && status != -ENOPROTOOPT) {
+                mlog_errno(status);
+                goto bail;
+        }
+
+        /* -ENOPROTOOPT from the net code means the other side isn't
+            listening for our message type -- that's fine, it means
+            his dlm isn't up, so we can consider him a 'yes' but not
+            joined into the domain.  */
+        if (status == -ENOPROTOOPT) {
+                status = 0;
+                *response = JOIN_OK_NO_MAP;
+        } else if (retval == JOIN_DISALLOW ||
+                   retval == JOIN_OK ||
+                   retval == JOIN_OK_NO_MAP) {
+                *response = retval;
+        } else {
+                status = -EINVAL;
+                mlog(ML_ERROR, "invalid response %d from node %u\n", retval,
+                     node);
+        }
+
+        mlog(0, "status %d, node %d response is %d\n", status, node,
+                  *response);
+
+bail:
+        return status;
+}
+
+static int dlm_send_one_join_assert(struct dlm_ctxt *dlm,
+                                    unsigned int node)
+{
+        int status;
+        struct dlm_assert_joined assert_msg;
+
+        mlog(0, "Sending join assert to node %u\n", node);
+
+        memset(&assert_msg, 0, sizeof(assert_msg));
+        assert_msg.node_idx = dlm->node_num;
+        assert_msg.name_len = strlen(dlm->name);
+        memcpy(assert_msg.domain, dlm->name, assert_msg.name_len);
+
+        status = o2net_send_message(DLM_ASSERT_JOINED_MSG, DLM_MOD_KEY,
+                                    &assert_msg, sizeof(assert_msg), node,
+                                    NULL);
+        if (status < 0)
+                mlog_errno(status);
+
+        return status;
+}
+
+static void dlm_send_join_asserts(struct dlm_ctxt *dlm,
+                                  unsigned long *node_map)
+{
+        int status, node, live;
+
+        status = 0;
+        node = -1;
+        while ((node = find_next_bit(node_map, O2NM_MAX_NODES,
+                                     node + 1)) < O2NM_MAX_NODES) {
+                if (node == dlm->node_num)
+                        continue;
+
+                do {
+                        /* It is very important that this message be
+                         * received so we spin until either the node
+                         * has died or it gets the message. */
+                        status = dlm_send_one_join_assert(dlm, node);
+
+                        spin_lock(&dlm->spinlock);
+                        live = test_bit(node, dlm->live_nodes_map);
+                        spin_unlock(&dlm->spinlock);
+
+                        if (status) {
+                                mlog(ML_ERROR, "Error return %d asserting "
+                                     "join on node %d\n", status, node);
+
+                                /* give us some time between errors... */
+                                if (live)
+                                        msleep(DLM_DOMAIN_BACKOFF_MS);
+                        }
+                } while (status && live);
+        }
+}
+
+struct domain_join_ctxt {
+        unsigned long live_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
+        unsigned long yes_resp_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
+};
+
+static int dlm_should_restart_join(struct dlm_ctxt *dlm,
+                                   struct domain_join_ctxt *ctxt,
+                                   enum dlm_query_join_response response)
+{
+        int ret;
+
+        if (response == JOIN_DISALLOW) {
+                mlog(0, "Latest response of disallow -- should restart\n");
+                return 1;
+        }
+
+        spin_lock(&dlm->spinlock);
+        /* For now, we restart the process if the node maps have
+         * changed at all */
+        ret = memcmp(ctxt->live_map, dlm->live_nodes_map,
+                     sizeof(dlm->live_nodes_map));
+        spin_unlock(&dlm->spinlock);
+
+        if (ret)
+                mlog(0, "Node maps changed -- should restart\n");
+
+        return ret;
+}
+
+static int dlm_try_to_join_domain(struct dlm_ctxt *dlm)
+{
+        int status = 0, tmpstat, node;
+        struct domain_join_ctxt *ctxt;
+        enum dlm_query_join_response response;
+
+        mlog_entry("%p", dlm);
+
+        ctxt = kcalloc(1, sizeof(*ctxt), GFP_KERNEL);
+        if (!ctxt) {
+                status = -ENOMEM;
+                mlog_errno(status);
+                goto bail;
+        }
+
+        /* group sem locking should work for us here -- we're already
+         * registered for heartbeat events so filling this should be
+         * atomic wrt getting those handlers called. */
+        o2hb_fill_node_map(dlm->live_nodes_map, sizeof(dlm->live_nodes_map));
+
+        spin_lock(&dlm->spinlock);
+        memcpy(ctxt->live_map, dlm->live_nodes_map, sizeof(ctxt->live_map));
+
+        __dlm_set_joining_node(dlm, dlm->node_num);
+
+        spin_unlock(&dlm->spinlock);
+
+        node = -1;
+        while ((node = find_next_bit(ctxt->live_map, O2NM_MAX_NODES,
+                                     node + 1)) < O2NM_MAX_NODES) {
+                if (node == dlm->node_num)
+                        continue;
+
+                status = dlm_request_join(dlm, node, &response);
+                if (status < 0) {
+                        mlog_errno(status);
+                        goto bail;
+                }
+
+                /* Ok, either we got a response or the node doesn't have a
+                 * dlm up. */
+                if (response == JOIN_OK)
+                        set_bit(node, ctxt->yes_resp_map);
+
+                if (dlm_should_restart_join(dlm, ctxt, response)) {
+                        status = -EAGAIN;
+                        goto bail;
+                }
+        }
+
+        mlog(0, "Yay, done querying nodes!\n");
+
+        /* Yay, everyone agree's we can join the domain. My domain is
+         * comprised of all nodes who were put in the
+         * yes_resp_map. Copy that into our domain map and send a join
+         * assert message to clean up everyone elses state. */
+        spin_lock(&dlm->spinlock);
+        memcpy(dlm->domain_map, ctxt->yes_resp_map,
+               sizeof(ctxt->yes_resp_map));
+        set_bit(dlm->node_num, dlm->domain_map);
+        spin_unlock(&dlm->spinlock);
+
+        dlm_send_join_asserts(dlm, ctxt->yes_resp_map);
+
+        /* Joined state *must* be set before the joining node
+         * information, otherwise the query_join handler may read no
+         * current joiner but a state of NEW and tell joining nodes
+         * we're not in the domain. */
+        spin_lock(&dlm_domain_lock);
+        dlm->dlm_state = DLM_CTXT_JOINED;
+        dlm->num_joins++;
+        spin_unlock(&dlm_domain_lock);
+
+bail:
+        spin_lock(&dlm->spinlock);
+        __dlm_set_joining_node(dlm, DLM_LOCK_RES_OWNER_UNKNOWN);
+        if (!status)
+                __dlm_print_nodes(dlm);
+        spin_unlock(&dlm->spinlock);
+
+        if (ctxt) {
+                /* Do we need to send a cancel message to any nodes? */
+                if (status < 0) {
+                        tmpstat = dlm_send_join_cancels(dlm,
+                                                        ctxt->yes_resp_map,
+                                                        sizeof(ctxt->yes_resp_map));
+                        if (tmpstat < 0)
+                                mlog_errno(tmpstat);
+                }
+                kfree(ctxt);
+        }
+
+        mlog(0, "returning %d\n", status);
+        return status;
+}
+
+static void dlm_unregister_domain_handlers(struct dlm_ctxt *dlm)
+{
+        o2hb_unregister_callback(&dlm->dlm_hb_up);
+        o2hb_unregister_callback(&dlm->dlm_hb_down);
+        o2net_unregister_handler_list(&dlm->dlm_domain_handlers);
+}
+
+static int dlm_register_domain_handlers(struct dlm_ctxt *dlm)
+{
+        int status;
+
+        mlog(0, "registering handlers.\n");
+
+        o2hb_setup_callback(&dlm->dlm_hb_down, O2HB_NODE_DOWN_CB,
+                            dlm_hb_node_down_cb, dlm, DLM_HB_NODE_DOWN_PRI);
+        status = o2hb_register_callback(&dlm->dlm_hb_down);
+        if (status)
+                goto bail;
+
+        o2hb_setup_callback(&dlm->dlm_hb_up, O2HB_NODE_UP_CB,
+                            dlm_hb_node_up_cb, dlm, DLM_HB_NODE_UP_PRI);
+        status = o2hb_register_callback(&dlm->dlm_hb_up);
+        if (status)
+                goto bail;
+
+        status = o2net_register_handler(DLM_MASTER_REQUEST_MSG, dlm->key,
+                                        sizeof(struct dlm_master_request),
+                                        dlm_master_request_handler,
+                                        dlm, &dlm->dlm_domain_handlers);
+        if (status)
+                goto bail;
+
+        status = o2net_register_handler(DLM_ASSERT_MASTER_MSG, dlm->key,
+                                        sizeof(struct dlm_assert_master),
+                                        dlm_assert_master_handler,
+                                        dlm, &dlm->dlm_domain_handlers);
+        if (status)
+                goto bail;
+
+        status = o2net_register_handler(DLM_CREATE_LOCK_MSG, dlm->key,
+                                        sizeof(struct dlm_create_lock),
+                                        dlm_create_lock_handler,
+                                        dlm, &dlm->dlm_domain_handlers);
+        if (status)
+                goto bail;
+
+        status = o2net_register_handler(DLM_CONVERT_LOCK_MSG, dlm->key,
+                                        DLM_CONVERT_LOCK_MAX_LEN,
+                                        dlm_convert_lock_handler,
+                                        dlm, &dlm->dlm_domain_handlers);
+        if (status)
+                goto bail;
+
+        status = o2net_register_handler(DLM_UNLOCK_LOCK_MSG, dlm->key,
+                                        DLM_UNLOCK_LOCK_MAX_LEN,
+                                        dlm_unlock_lock_handler,
+                                        dlm, &dlm->dlm_domain_handlers);
+        if (status)
+                goto bail;
+
+        status = o2net_register_handler(DLM_PROXY_AST_MSG, dlm->key,
+                                        DLM_PROXY_AST_MAX_LEN,
+                                        dlm_proxy_ast_handler,
+                                        dlm, &dlm->dlm_domain_handlers);
+        if (status)
+                goto bail;
+
+        status = o2net_register_handler(DLM_EXIT_DOMAIN_MSG, dlm->key,
+                                        sizeof(struct dlm_exit_domain),
+                                        dlm_exit_domain_handler,
+                                        dlm, &dlm->dlm_domain_handlers);
+        if (status)
+                goto bail;
+
+        status = o2net_register_handler(DLM_MIGRATE_REQUEST_MSG, dlm->key,
+                                        sizeof(struct dlm_migrate_request),
+                                        dlm_migrate_request_handler,
+                                        dlm, &dlm->dlm_domain_handlers);
+        if (status)
+                goto bail;
+
+        status = o2net_register_handler(DLM_MIG_LOCKRES_MSG, dlm->key,
+                                        DLM_MIG_LOCKRES_MAX_LEN,
+                                        dlm_mig_lockres_handler,
+                                        dlm, &dlm->dlm_domain_handlers);
+        if (status)
+                goto bail;
+
+        status = o2net_register_handler(DLM_MASTER_REQUERY_MSG, dlm->key,
+                                        sizeof(struct dlm_master_requery),
+                                        dlm_master_requery_handler,
+                                        dlm, &dlm->dlm_domain_handlers);
+        if (status)
+                goto bail;
+
+        status = o2net_register_handler(DLM_LOCK_REQUEST_MSG, dlm->key,
+                                        sizeof(struct dlm_lock_request),
+                                        dlm_request_all_locks_handler,
+                                        dlm, &dlm->dlm_domain_handlers);
+        if (status)
+                goto bail;
+
+        status = o2net_register_handler(DLM_RECO_DATA_DONE_MSG, dlm->key,
+                                        sizeof(struct dlm_reco_data_done),
+                                        dlm_reco_data_done_handler,
+                                        dlm, &dlm->dlm_domain_handlers);
+        if (status)
+                goto bail;
+
+        status = o2net_register_handler(DLM_BEGIN_RECO_MSG, dlm->key,
+                                        sizeof(struct dlm_begin_reco),
+                                        dlm_begin_reco_handler,
+                                        dlm, &dlm->dlm_domain_handlers);
+        if (status)
+                goto bail;
+
+        status = o2net_register_handler(DLM_FINALIZE_RECO_MSG, dlm->key,
+                                        sizeof(struct dlm_finalize_reco),
+                                        dlm_finalize_reco_handler,
+                                        dlm, &dlm->dlm_domain_handlers);
+        if (status)
+                goto bail;
+
+bail:
+        if (status)
+                dlm_unregister_domain_handlers(dlm);
+
+        return status;
+}
+
+static int dlm_join_domain(struct dlm_ctxt *dlm)
+{
+        int status;
+
+        BUG_ON(!dlm);
+
+        mlog(0, "Join domain %s\n", dlm->name);
+
+        status = dlm_register_domain_handlers(dlm);
+        if (status) {
+                mlog_errno(status);
+                goto bail;
+        }
+
+        status = dlm_launch_thread(dlm);
+        if (status < 0) {
+                mlog_errno(status);
+                goto bail;
+        }
+
+        status = dlm_launch_recovery_thread(dlm);
+        if (status < 0) {
+                mlog_errno(status);
+                goto bail;
+        }
+
+        do {
+                unsigned int backoff;
+                status = dlm_try_to_join_domain(dlm);
+
+                /* If we're racing another node to the join, then we
+                 * need to back off temporarily and let them
+                 * complete. */
+                if (status == -EAGAIN) {
+                        if (signal_pending(current)) {
+                                status = -ERESTARTSYS;
+                                goto bail;
+                        }
+
+                        /*
+                         * <chip> After you!
+                         * <dale> No, after you!
+                         * <chip> I insist!
+                         * <dale> But you first!
+                         * ...
+                         */
+                        backoff = (unsigned int)(jiffies & 0x3);
+                        backoff *= DLM_DOMAIN_BACKOFF_MS;
+                        mlog(0, "backoff %d\n", backoff);
+                        msleep(backoff);
+                }
+        } while (status == -EAGAIN);
+
+        if (status < 0) {
+                mlog_errno(status);
+                goto bail;
+        }
+
+        status = 0;
+bail:
+        wake_up(&dlm_domain_events);
+
+        if (status) {
+                dlm_unregister_domain_handlers(dlm);
+                dlm_complete_thread(dlm);
+                dlm_complete_recovery_thread(dlm);
+        }
+
+        return status;
+}
+
+static struct dlm_ctxt *dlm_alloc_ctxt(const char *domain,
+                                u32 key)
+{
+        int i;
+        struct dlm_ctxt *dlm = NULL;
+
+        dlm = kcalloc(1, sizeof(*dlm), GFP_KERNEL);
+        if (!dlm) {
+                mlog_errno(-ENOMEM);
+                goto leave;
+        }
+
+        dlm->name = kmalloc(strlen(domain) + 1, GFP_KERNEL);
+        if (dlm->name == NULL) {
+                mlog_errno(-ENOMEM);
+                kfree(dlm);
+                dlm = NULL;
+                goto leave;
+        }
+
+        dlm->resources = (struct list_head *) __get_free_page(GFP_KERNEL);
+        if (!dlm->resources) {
+                mlog_errno(-ENOMEM);
+                kfree(dlm->name);
+                kfree(dlm);
+                dlm = NULL;
+                goto leave;
+        }
+        memset(dlm->resources, 0, PAGE_SIZE);
+
+        for (i=0; i<DLM_HASH_SIZE; i++)
+                INIT_LIST_HEAD(&dlm->resources[i]);
+
+        strcpy(dlm->name, domain);
+        dlm->key = key;
+        dlm->node_num = o2nm_this_node();
+
+        spin_lock_init(&dlm->spinlock);
+        spin_lock_init(&dlm->master_lock);
+        spin_lock_init(&dlm->ast_lock);
+        INIT_LIST_HEAD(&dlm->list);
+        INIT_LIST_HEAD(&dlm->dirty_list);
+        INIT_LIST_HEAD(&dlm->reco.resources);
+        INIT_LIST_HEAD(&dlm->reco.received);
+        INIT_LIST_HEAD(&dlm->reco.node_data);
+        INIT_LIST_HEAD(&dlm->purge_list);
+        INIT_LIST_HEAD(&dlm->dlm_domain_handlers);
+        dlm->reco.state = 0;
+
+        INIT_LIST_HEAD(&dlm->pending_asts);
+        INIT_LIST_HEAD(&dlm->pending_basts);
+
+        mlog(0, "dlm->recovery_map=%p, &(dlm->recovery_map[0])=%p\n",
+                  dlm->recovery_map, &(dlm->recovery_map[0]));
+
+        memset(dlm->recovery_map, 0, sizeof(dlm->recovery_map));
+        memset(dlm->live_nodes_map, 0, sizeof(dlm->live_nodes_map));
+        memset(dlm->domain_map, 0, sizeof(dlm->domain_map));
+
+        dlm->dlm_thread_task = NULL;
+        dlm->dlm_reco_thread_task = NULL;
+        init_waitqueue_head(&dlm->dlm_thread_wq);
+        init_waitqueue_head(&dlm->dlm_reco_thread_wq);
+        init_waitqueue_head(&dlm->reco.event);
+        init_waitqueue_head(&dlm->ast_wq);
+        init_waitqueue_head(&dlm->migration_wq);
+        INIT_LIST_HEAD(&dlm->master_list);
+        INIT_LIST_HEAD(&dlm->mle_hb_events);
+
+        dlm->joining_node = DLM_LOCK_RES_OWNER_UNKNOWN;
+        init_waitqueue_head(&dlm->dlm_join_events);
+
+        dlm->reco.new_master = O2NM_INVALID_NODE_NUM;
+        dlm->reco.dead_node = O2NM_INVALID_NODE_NUM;
+        atomic_set(&dlm->local_resources, 0);
+        atomic_set(&dlm->remote_resources, 0);
+        atomic_set(&dlm->unknown_resources, 0);
+
+        spin_lock_init(&dlm->work_lock);
+        INIT_LIST_HEAD(&dlm->work_list);
+        INIT_WORK(&dlm->dispatched_work, dlm_dispatch_work, dlm);
+
+        kref_init(&dlm->dlm_refs);
+        dlm->dlm_state = DLM_CTXT_NEW;
+
+        INIT_LIST_HEAD(&dlm->dlm_eviction_callbacks);
+
+        mlog(0, "context init: refcount %u\n",
+                  atomic_read(&dlm->dlm_refs.refcount));
+
+leave:
+        return dlm;
+}
+
+/*
+ * dlm_register_domain: one-time setup per "domain"
+ */
+struct dlm_ctxt * dlm_register_domain(const char *domain,
+                               u32 key)
+{
+        int ret;
+        struct dlm_ctxt *dlm = NULL;
+        struct dlm_ctxt *new_ctxt = NULL;
+
+        if (strlen(domain) > O2NM_MAX_NAME_LEN) {
+                ret = -ENAMETOOLONG;
+                mlog(ML_ERROR, "domain name length too long\n");
+                goto leave;
+        }
+
+        if (!o2hb_check_local_node_heartbeating()) {
+                mlog(ML_ERROR, "the local node has not been configured, or is "
+                     "not heartbeating\n");
+                ret = -EPROTO;
+                goto leave;
+        }
+
+        mlog(0, "register called for domain \"%s\"\n", domain);
+
+retry:
+        dlm = NULL;
+        if (signal_pending(current)) {
+                ret = -ERESTARTSYS;
+                mlog_errno(ret);
+                goto leave;
+        }
+
+        spin_lock(&dlm_domain_lock);
+
+        dlm = __dlm_lookup_domain(domain);
+        if (dlm) {
+                if (dlm->dlm_state != DLM_CTXT_JOINED) {
+                        spin_unlock(&dlm_domain_lock);
+
+                        mlog(0, "This ctxt is not joined yet!\n");
+                        wait_event_interruptible(dlm_domain_events,
+                                                 dlm_wait_on_domain_helper(
+                                                         domain));
+                        goto retry;
+                }
+
+                __dlm_get(dlm);
+                dlm->num_joins++;
+
+                spin_unlock(&dlm_domain_lock);
+
+                ret = 0;
+                goto leave;
+        }
+
+        /* doesn't exist */
+        if (!new_ctxt) {
+                spin_unlock(&dlm_domain_lock);
+
+                new_ctxt = dlm_alloc_ctxt(domain, key);
+                if (new_ctxt)
+                        goto retry;
+
+                ret = -ENOMEM;
+                mlog_errno(ret);
+                goto leave;
+        }
+
+        /* a little variable switch-a-roo here... */
+        dlm = new_ctxt;
+        new_ctxt = NULL;
+
+        /* add the new domain */
+        list_add_tail(&dlm->list, &dlm_domains);
+        spin_unlock(&dlm_domain_lock);
+
+        ret = dlm_join_domain(dlm);
+        if (ret) {
+                mlog_errno(ret);
+                dlm_put(dlm);
+                goto leave;
+        }
+
+        ret = 0;
+leave:
+        if (new_ctxt)
+                dlm_free_ctxt_mem(new_ctxt);
+
+        if (ret < 0)
+                dlm = ERR_PTR(ret);
+
+        return dlm;
+}
+EXPORT_SYMBOL_GPL(dlm_register_domain);
+
+static LIST_HEAD(dlm_join_handlers);
+
+static void dlm_unregister_net_handlers(void)
+{
+        o2net_unregister_handler_list(&dlm_join_handlers);
+}
+
+static int dlm_register_net_handlers(void)
+{
+        int status = 0;
+
+        status = o2net_register_handler(DLM_QUERY_JOIN_MSG, DLM_MOD_KEY,
+                                        sizeof(struct dlm_query_join_request),
+                                        dlm_query_join_handler,
+                                        NULL, &dlm_join_handlers);
+        if (status)
+                goto bail;
+
+        status = o2net_register_handler(DLM_ASSERT_JOINED_MSG, DLM_MOD_KEY,
+                                        sizeof(struct dlm_assert_joined),
+                                        dlm_assert_joined_handler,
+                                        NULL, &dlm_join_handlers);
+        if (status)
+                goto bail;
+
+        status = o2net_register_handler(DLM_CANCEL_JOIN_MSG, DLM_MOD_KEY,
+                                        sizeof(struct dlm_cancel_join),
+                                        dlm_cancel_join_handler,
+                                        NULL, &dlm_join_handlers);
+
+bail:
+        if (status < 0)
+                dlm_unregister_net_handlers();
+
+        return status;
+}
+
+/* Domain eviction callback handling.
+ *
+ * The file system requires notification of node death *before* the
+ * dlm completes it's recovery work, otherwise it may be able to
+ * acquire locks on resources requiring recovery. Since the dlm can
+ * evict a node from it's domain *before* heartbeat fires, a similar
+ * mechanism is required. */
+
+/* Eviction is not expected to happen often, so a per-domain lock is
+ * not necessary. Eviction callbacks are allowed to sleep for short
+ * periods of time. */
+static DECLARE_RWSEM(dlm_callback_sem);
+
+void dlm_fire_domain_eviction_callbacks(struct dlm_ctxt *dlm,
+                                        int node_num)
+{
+        struct list_head *iter;
+        struct dlm_eviction_cb *cb;
+
+        down_read(&dlm_callback_sem);
+        list_for_each(iter, &dlm->dlm_eviction_callbacks) {
+                cb = list_entry(iter, struct dlm_eviction_cb, ec_item);
+
+                cb->ec_func(node_num, cb->ec_data);
+        }
+        up_read(&dlm_callback_sem);
+}
+
+void dlm_setup_eviction_cb(struct dlm_eviction_cb *cb,
+                           dlm_eviction_func *f,
+                           void *data)
+{
+        INIT_LIST_HEAD(&cb->ec_item);
+        cb->ec_func = f;
+        cb->ec_data = data;
+}
+EXPORT_SYMBOL_GPL(dlm_setup_eviction_cb);
+
+void dlm_register_eviction_cb(struct dlm_ctxt *dlm,
+                              struct dlm_eviction_cb *cb)
+{
+        down_write(&dlm_callback_sem);
+        list_add_tail(&cb->ec_item, &dlm->dlm_eviction_callbacks);
+        up_write(&dlm_callback_sem);
+}
+EXPORT_SYMBOL_GPL(dlm_register_eviction_cb);
+
+void dlm_unregister_eviction_cb(struct dlm_eviction_cb *cb)
+{
+        down_write(&dlm_callback_sem);
+        list_del_init(&cb->ec_item);
+        up_write(&dlm_callback_sem);
+}
+EXPORT_SYMBOL_GPL(dlm_unregister_eviction_cb);
+
+static int __init dlm_init(void)
+{
+        int status;
+
+        dlm_print_version();
+
+        status = dlm_init_mle_cache();
+        if (status)
+                return -1;
+
+        status = dlm_register_net_handlers();
+        if (status) {
+                dlm_destroy_mle_cache();
+                return -1;
+        }
+
+        return 0;
+}
+
+static void __exit dlm_exit (void)
+{
+        dlm_unregister_net_handlers();
+        dlm_destroy_mle_cache();
+}
+
+MODULE_AUTHOR("Oracle");
+MODULE_LICENSE("GPL");
+
+module_init(dlm_init);
+module_exit(dlm_exit);