dlmdomain.c

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/* -*- 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/init.h>
#include <linux/spinlock.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/debugfs.h>

#include "cluster/heartbeat.h"
#include "cluster/nodemanager.h"
#include "cluster/tcp.h"

#include "dlmapi.h"
#include "dlmcommon.h"
#include "dlmdomain.h"
#include "dlmdebug.h"

#include "dlmver.h"

#define MLOG_MASK_PREFIX (ML_DLM|ML_DLM_DOMAIN)
#include "cluster/masklog.h"

/*
 * ocfs2 node maps are array of long int, which limits to send them freely
 * across the wire due to endianness issues. To workaround this, we convert
 * long ints to byte arrays. Following 3 routines are helper functions to
 * set/test/copy bits within those array of bytes
 */
static inline void byte_set_bit(u8 nr, u8 map[])
{
    map[nr >> 3] |= (1UL << (nr & 7));
}

static inline int byte_test_bit(u8 nr, u8 map[])
{
    return ((1UL << (nr & 7)) & (map[nr >> 3])) != 0;
}

static inline void byte_copymap(u8 dmap[], unsigned long smap[],
            unsigned int sz)
{
    unsigned int nn;

    if (!sz)
        return;

    memset(dmap, 0, ((sz + 7) >> 3));
    for (nn = 0 ; nn < sz; nn++)
        if (test_bit(nn, smap))
            byte_set_bit(nn, dmap);
}

static void dlm_free_pagevec(void **vec, int pages)
{
    while (pages--)
        free_page((unsigned long)vec[pages]);
    kfree(vec);
}

static void **dlm_alloc_pagevec(int pages)
{
    void **vec = kmalloc(pages * sizeof(void *), GFP_KERNEL);
    int i;

    if (!vec)
        return NULL;

    for (i = 0; i < pages; i++)
        if (!(vec[i] = (void *)__get_free_page(GFP_KERNEL)))
            goto out_free;

    mlog(0, "Allocated DLM hash pagevec; %d pages (%lu expected), %lu buckets per page\n",
         pages, (unsigned long)DLM_HASH_PAGES,
         (unsigned long)DLM_BUCKETS_PER_PAGE);
    return vec;
out_free:
    dlm_free_pagevec(vec, i);
    return NULL;
}

/*
 *
 * 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
 *
 */

DEFINE_SPINLOCK(dlm_domain_lock);
LIST_HEAD(dlm_domains);
static DECLARE_WAIT_QUEUE_HEAD(dlm_domain_events);

/*
 * The supported protocol version for DLM communication.  Running domains
 * will have a negotiated version with the same major number and a minor
 * number equal or smaller.  The dlm_ctxt->dlm_locking_proto field should
 * be used to determine what a running domain is actually using.
 *
 * New in version 1.1:
 *  - Message DLM_QUERY_REGION added to support global heartbeat
 *  - Message DLM_QUERY_NODEINFO added to allow online node removes
 * New in version 1.2:
 *  - Message DLM_BEGIN_EXIT_DOMAIN_MSG added to mark start of exit domain
 */
static const struct dlm_protocol_version dlm_protocol = {
    .pv_major = 1,
    .pv_minor = 2,
};

#define DLM_DOMAIN_BACKOFF_MS 200

static int dlm_query_join_handler(struct o2net_msg *msg, u32 len, void *data,
                  void **ret_data);
static int dlm_assert_joined_handler(struct o2net_msg *msg, u32 len, void *data,
                     void **ret_data);
static int dlm_cancel_join_handler(struct o2net_msg *msg, u32 len, void *data,
                   void **ret_data);
static int dlm_query_region_handler(struct o2net_msg *msg, u32 len,
                    void *data, void **ret_data);
static int dlm_exit_domain_handler(struct o2net_msg *msg, u32 len, void *data,
                   void **ret_data);
static int dlm_protocol_compare(struct dlm_protocol_version *existing,
                struct dlm_protocol_version *request);

static void dlm_unregister_domain_handlers(struct dlm_ctxt *dlm);

void __dlm_unhash_lockres(struct dlm_ctxt *dlm, struct dlm_lock_resource *res)
{
    if (hlist_unhashed(&res->hash_node))
        return;

    mlog(0, "%s: Unhash res %.*s\n", dlm->name, res->lockname.len,
         res->lockname.name);
    hlist_del_init(&res->hash_node);
    dlm_lockres_put(res);
}

void __dlm_insert_lockres(struct dlm_ctxt *dlm, struct dlm_lock_resource *res)
{
    struct hlist_head *bucket;
    struct qstr *q;

    assert_spin_locked(&dlm->spinlock);

    q = &res->lockname;
    bucket = dlm_lockres_hash(dlm, q->hash);

    /* get a reference for our hashtable */
    dlm_lockres_get(res);

    hlist_add_head(&res->hash_node, bucket);

    mlog(0, "%s: Hash res %.*s\n", dlm->name, res->lockname.len,
         res->lockname.name);
}

struct dlm_lock_resource * __dlm_lookup_lockres_full(struct dlm_ctxt *dlm,
                             const char *name,
                             unsigned int len,
                             unsigned int hash)
{
    struct hlist_head *bucket;
    struct hlist_node *list;

    mlog(0, "%.*s\n", len, name);

    assert_spin_locked(&dlm->spinlock);

    bucket = dlm_lockres_hash(dlm, hash);

    hlist_for_each(list, bucket) {
        struct dlm_lock_resource *res = hlist_entry(list,
            struct dlm_lock_resource, hash_node);
        if (res->lockname.name[0] != name[0])
            continue;
        if (unlikely(res->lockname.len != len))
            continue;
        if (memcmp(res->lockname.name + 1, name + 1, len - 1))
            continue;
        dlm_lockres_get(res);
        return res;
    }
    return NULL;
}

/* intended to be called by functions which do not care about lock
 * resources which are being purged (most net _handler functions).
 * this will return NULL for any lock resource which is found but
 * currently in the process of dropping its mastery reference.
 * use __dlm_lookup_lockres_full when you need the lock resource
 * regardless (e.g. dlm_get_lock_resource) */
struct dlm_lock_resource * __dlm_lookup_lockres(struct dlm_ctxt *dlm,
                        const char *name,
                        unsigned int len,
                        unsigned int hash)
{
    struct dlm_lock_resource *res = NULL;

    mlog(0, "%.*s\n", len, name);

    assert_spin_locked(&dlm->spinlock);

    res = __dlm_lookup_lockres_full(dlm, name, len, hash);
    if (res) {
        spin_lock(&res->spinlock);
        if (res->state & DLM_LOCK_RES_DROPPING_REF) {
            spin_unlock(&res->spinlock);
            dlm_lockres_put(res);
            return NULL;
        }
        spin_unlock(&res->spinlock);
    }

    return res;
}

struct dlm_lock_resource * dlm_lookup_lockres(struct dlm_ctxt *dlm,
                    const char *name,
                    unsigned int len)
{
    struct dlm_lock_resource *res;
    unsigned int hash = dlm_lockid_hash(name, len);

    spin_lock(&dlm->spinlock);
    res = __dlm_lookup_lockres(dlm, name, len, hash);
    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)
{
    dlm_destroy_debugfs_subroot(dlm);

    if (dlm->lockres_hash)
        dlm_free_pagevec((void **)dlm->lockres_hash, DLM_HASH_PAGES);

    if (dlm->master_hash)
        dlm_free_pagevec((void **)dlm->master_hash, DLM_HASH_PAGES);

    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_destroy_dlm_worker(struct dlm_ctxt *dlm)
{
    if (dlm->dlm_worker) {
        flush_workqueue(dlm->dlm_worker);
        destroy_workqueue(dlm->dlm_worker);
        dlm->dlm_worker = NULL;
    }
}

static void dlm_complete_dlm_shutdown(struct dlm_ctxt *dlm)
{
    dlm_unregister_domain_handlers(dlm);
    dlm_debug_shutdown(dlm);
    dlm_complete_thread(dlm);
    dlm_complete_recovery_thread(dlm);
    dlm_destroy_dlm_worker(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 int dlm_migrate_all_locks(struct dlm_ctxt *dlm)
{
    int i, num, n, ret = 0;
    struct dlm_lock_resource *res;
    struct hlist_node *iter;
    struct hlist_head *bucket;
    int dropped;

    mlog(0, "Migrating locks from domain %s\n", dlm->name);

    num = 0;
    spin_lock(&dlm->spinlock);
    for (i = 0; i < DLM_HASH_BUCKETS; i++) {
redo_bucket:
        n = 0;
        bucket = dlm_lockres_hash(dlm, i);
        iter = bucket->first;
        while (iter) {
            n++;
            res = hlist_entry(iter, struct dlm_lock_resource,
                      hash_node);
            dlm_lockres_get(res);
            /* migrate, if necessary.  this will drop the dlm
             * spinlock and retake it if it does migration. */
            dropped = dlm_empty_lockres(dlm, res);

            spin_lock(&res->spinlock);
            if (dropped)
                __dlm_lockres_calc_usage(dlm, res);
            else
                iter = res->hash_node.next;
            spin_unlock(&res->spinlock);

            dlm_lockres_put(res);

            if (dropped) {
                cond_resched_lock(&dlm->spinlock);
                goto redo_bucket;
            }
        }
        cond_resched_lock(&dlm->spinlock);
        num += n;
    }
    spin_unlock(&dlm->spinlock);
    wake_up(&dlm->dlm_thread_wq);

    /* let the dlm thread take care of purging, keep scanning until
     * nothing remains in the hash */
    if (num) {
        mlog(0, "%s: %d lock resources in hash last pass\n",
             dlm->name, num);
        ret = -EAGAIN;
    }
    mlog(0, "DONE Migrating locks from domain %s\n", dlm->name);
    return ret;
}

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 int dlm_begin_exit_domain_handler(struct o2net_msg *msg, u32 len,
                     void *data, void **ret_data)
{
    struct dlm_ctxt *dlm = data;
    unsigned int node;
    struct dlm_exit_domain *exit_msg = (struct dlm_exit_domain *) msg->buf;

    if (!dlm_grab(dlm))
        return 0;

    node = exit_msg->node_idx;
    mlog(0, "%s: Node %u sent a begin exit domain message\n", dlm->name, node);

    spin_lock(&dlm->spinlock);
    set_bit(node, dlm->exit_domain_map);
    spin_unlock(&dlm->spinlock);

    dlm_put(dlm);

    return 0;
}

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, num = 0;

    assert_spin_locked(&dlm->spinlock);

    printk("( ");
    while ((node = find_next_bit(dlm->domain_map, O2NM_MAX_NODES,
                     node + 1)) < O2NM_MAX_NODES) {
        printk("%d ", node);
        ++num;
    }
    printk(") %u nodes\n", num);
}

static int dlm_exit_domain_handler(struct o2net_msg *msg, u32 len, void *data,
                   void **ret_data)
{
    struct dlm_ctxt *dlm = data;
    unsigned int node;
    struct dlm_exit_domain *exit_msg = (struct dlm_exit_domain *) msg->buf;

    mlog(0, "%p %u %p", msg, len, data);

    if (!dlm_grab(dlm))
        return 0;

    node = exit_msg->node_idx;

    spin_lock(&dlm->spinlock);
    clear_bit(node, dlm->domain_map);
    clear_bit(node, dlm->exit_domain_map);
    printk(KERN_NOTICE "o2dlm: Node %u leaves domain %s ", node, dlm->name);
    __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, u32 msg_type,
                    unsigned int node)
{
    int status;
    struct dlm_exit_domain leave_msg;

    mlog(0, "%s: Sending domain exit message %u to node %u\n", dlm->name,
         msg_type, node);

    memset(&leave_msg, 0, sizeof(leave_msg));
    leave_msg.node_idx = dlm->node_num;

    status = o2net_send_message(msg_type, dlm->key, &leave_msg,
                    sizeof(leave_msg), node, NULL);
    if (status < 0)
        mlog(ML_ERROR, "Error %d sending domain exit message %u "
             "to node %u on domain %s\n", status, msg_type, node,
             dlm->name);

    return status;
}

static void dlm_begin_exit_domain(struct dlm_ctxt *dlm)
{
    int node = -1;

    /* Support for begin exit domain was added in 1.2 */
    if (dlm->dlm_locking_proto.pv_major == 1 &&
        dlm->dlm_locking_proto.pv_minor < 2)
        return;

    /*
     * Unlike DLM_EXIT_DOMAIN_MSG, DLM_BEGIN_EXIT_DOMAIN_MSG is purely
     * informational. Meaning if a node does not receive the message,
     * so be it.
     */
    spin_lock(&dlm->spinlock);
    while (1) {
        node = find_next_bit(dlm->domain_map, O2NM_MAX_NODES, node + 1);
        if (node >= O2NM_MAX_NODES)
            break;
        if (node == dlm->node_num)
            continue;

        spin_unlock(&dlm->spinlock);
        dlm_send_one_domain_exit(dlm, DLM_BEGIN_EXIT_DOMAIN_MSG, node);
        spin_lock(&dlm->spinlock);
    }
    spin_unlock(&dlm->spinlock);
}

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, DLM_EXIT_DOMAIN_MSG,
                          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;
    struct dlm_lock_resource *res;

    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);
        dlm_begin_exit_domain(dlm);

        /* We changed dlm state, notify the thread */
        dlm_kick_thread(dlm, NULL);

        while (dlm_migrate_all_locks(dlm)) {
            /* Give dlm_thread time to purge the lockres' */
            msleep(500);
            mlog(0, "%s: more migration to do\n", dlm->name);
        }

        /* This list should be empty. If not, print remaining lockres */
        if (!list_empty(&dlm->tracking_list)) {
            mlog(ML_ERROR, "Following lockres' are still on the "
                 "tracking list:\n");
            list_for_each_entry(res, &dlm->tracking_list, tracking)
                dlm_print_one_lock_resource(res);
        }

        dlm_mark_domain_leaving(dlm);
        dlm_leave_domain(dlm);
        printk(KERN_NOTICE "o2dlm: Leaving domain %s\n", dlm->name);
        dlm_force_free_mles(dlm);
        dlm_complete_dlm_shutdown(dlm);
    }
    dlm_put(dlm);
}
EXPORT_SYMBOL_GPL(dlm_unregister_domain);

static int dlm_query_join_proto_check(char *proto_type, int node,
                      struct dlm_protocol_version *ours,
                      struct dlm_protocol_version *request)
{
    int rc;
    struct dlm_protocol_version proto = *request;

    if (!dlm_protocol_compare(ours, &proto)) {
        mlog(0,
             "node %u wanted to join with %s locking protocol "
             "%u.%u, we respond with %u.%u\n",
             node, proto_type,
             request->pv_major,
             request->pv_minor,
             proto.pv_major, proto.pv_minor);
        request->pv_minor = proto.pv_minor;
        rc = 0;
    } else {
        mlog(ML_NOTICE,
             "Node %u wanted to join with %s locking "
             "protocol %u.%u, but we have %u.%u, disallowing\n",
             node, proto_type,
             request->pv_major,
             request->pv_minor,
             ours->pv_major,
             ours->pv_minor);
        rc = 1;
    }

    return rc;
}

/*
 * struct dlm_query_join_packet is made up of four one-byte fields.  They
 * are effectively in big-endian order already.  However, little-endian
 * machines swap them before putting the packet on the wire (because
 * query_join's response is a status, and that status is treated as a u32
 * on the wire).  Thus, a big-endian and little-endian machines will treat
 * this structure differently.
 *
 * The solution is to have little-endian machines swap the structure when
 * converting from the structure to the u32 representation.  This will
 * result in the structure having the correct format on the wire no matter
 * the host endian format.
 */
static void dlm_query_join_packet_to_wire(struct dlm_query_join_packet *packet,
                      u32 *wire)
{
    union dlm_query_join_response response;

    response.packet = *packet;
    *wire = be32_to_cpu(response.intval);
}

static void dlm_query_join_wire_to_packet(u32 wire,
                      struct dlm_query_join_packet *packet)
{
    union dlm_query_join_response response;

    response.intval = cpu_to_be32(wire);
    *packet = response.packet;
}

static int dlm_query_join_handler(struct o2net_msg *msg, u32 len, void *data,
                  void **ret_data)
{
    struct dlm_query_join_request *query;
    struct dlm_query_join_packet packet = {
        .code = JOIN_DISALLOW,
    };
    struct dlm_ctxt *dlm = NULL;
    u32 response;
    u8 nodenum;

    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);

        packet.code = JOIN_DISALLOW;
        goto respond;
    }

    packet.code = JOIN_OK_NO_MAP;

    spin_lock(&dlm_domain_lock);
    dlm = __dlm_lookup_domain_full(query->domain, query->name_len);
    if (!dlm)
        goto unlock_respond;

    /*
     * There is a small window where the joining node may not see the
     * node(s) that just left but still part of the cluster. DISALLOW
     * join request if joining node has different node map.
     */
    nodenum=0;
    while (nodenum < O2NM_MAX_NODES) {
        if (test_bit(nodenum, dlm->domain_map)) {
            if (!byte_test_bit(nodenum, query->node_map)) {
                mlog(0, "disallow join as node %u does not "
                     "have node %u in its nodemap\n",
                     query->node_idx, nodenum);
                packet.code = JOIN_DISALLOW;
                goto unlock_respond;
            }
        }
        nodenum++;
    }

    /* Once the dlm ctxt is marked as leaving then we don't want
     * to be put in someone's domain map.
     * Also, explicitly disallow joining at certain troublesome
     * times (ie. during recovery). */
    if (dlm && dlm->dlm_state != DLM_CTXT_LEAVING) {
        int bit = query->node_idx;
        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. */
            packet.code = JOIN_OK_NO_MAP;
        } else if (dlm->joining_node != DLM_LOCK_RES_OWNER_UNKNOWN) {
            /* Disallow parallel joins. */
            packet.code = JOIN_DISALLOW;
        } else if (dlm->reco.state & DLM_RECO_STATE_ACTIVE) {
            mlog(0, "node %u trying to join, but recovery "
                 "is ongoing.\n", bit);
            packet.code = JOIN_DISALLOW;
        } else if (test_bit(bit, dlm->recovery_map)) {
            mlog(0, "node %u trying to join, but it "
                 "still needs recovery.\n", bit);
            packet.code = JOIN_DISALLOW;
        } else if (test_bit(bit, dlm->domain_map)) {
            mlog(0, "node %u trying to join, but it "
                 "is still in the domain! needs recovery?\n",
                 bit);
            packet.code = 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. */

            /* Make sure we speak compatible locking protocols.  */
            if (dlm_query_join_proto_check("DLM", bit,
                               &dlm->dlm_locking_proto,
                               &query->dlm_proto)) {
                packet.code = JOIN_PROTOCOL_MISMATCH;
            } else if (dlm_query_join_proto_check("fs", bit,
                                  &dlm->fs_locking_proto,
                                  &query->fs_proto)) {
                packet.code = JOIN_PROTOCOL_MISMATCH;
            } else {
                packet.dlm_minor = query->dlm_proto.pv_minor;
                packet.fs_minor = query->fs_proto.pv_minor;
                packet.code = JOIN_OK;
                __dlm_set_joining_node(dlm, query->node_idx);
            }
        }

        spin_unlock(&dlm->spinlock);
    }
unlock_respond:
    spin_unlock(&dlm_domain_lock);

respond:
    mlog(0, "We respond with %u\n", packet.code);

    dlm_query_join_packet_to_wire(&packet, &response);
    return response;
}

static int dlm_assert_joined_handler(struct o2net_msg *msg, u32 len, void *data,
                     void **ret_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);
        clear_bit(assert->node_idx, dlm->exit_domain_map);
        __dlm_set_joining_node(dlm, DLM_LOCK_RES_OWNER_UNKNOWN);

        printk(KERN_NOTICE "o2dlm: Node %u joins domain %s ",
               assert->node_idx, dlm->name);
        __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_match_regions(struct dlm_ctxt *dlm,
                 struct dlm_query_region *qr,
                 char *local, int locallen)
{
    char *remote = qr->qr_regions;
    char *l, *r;
    int localnr, i, j, foundit;
    int status = 0;

    if (!o2hb_global_heartbeat_active()) {
        if (qr->qr_numregions) {
            mlog(ML_ERROR, "Domain %s: Joining node %d has global "
                 "heartbeat enabled but local node %d does not\n",
                 qr->qr_domain, qr->qr_node, dlm->node_num);
            status = -EINVAL;
        }
        goto bail;
    }

    if (o2hb_global_heartbeat_active() && !qr->qr_numregions) {
        mlog(ML_ERROR, "Domain %s: Local node %d has global "
             "heartbeat enabled but joining node %d does not\n",
             qr->qr_domain, dlm->node_num, qr->qr_node);
        status = -EINVAL;
        goto bail;
    }

    r = remote;
    for (i = 0; i < qr->qr_numregions; ++i) {
        mlog(0, "Region %.*s\n", O2HB_MAX_REGION_NAME_LEN, r);
        r += O2HB_MAX_REGION_NAME_LEN;
    }

    localnr = min(O2NM_MAX_REGIONS, locallen/O2HB_MAX_REGION_NAME_LEN);
    localnr = o2hb_get_all_regions(local, (u8)localnr);

    /* compare local regions with remote */
    l = local;
    for (i = 0; i < localnr; ++i) {
        foundit = 0;
        r = remote;
        for (j = 0; j <= qr->qr_numregions; ++j) {
            if (!memcmp(l, r, O2HB_MAX_REGION_NAME_LEN)) {
                foundit = 1;
                break;
            }
            r += O2HB_MAX_REGION_NAME_LEN;
        }
        if (!foundit) {
            status = -EINVAL;
            mlog(ML_ERROR, "Domain %s: Region '%.*s' registered "
                 "in local node %d but not in joining node %d\n",
                 qr->qr_domain, O2HB_MAX_REGION_NAME_LEN, l,
                 dlm->node_num, qr->qr_node);
            goto bail;
        }
        l += O2HB_MAX_REGION_NAME_LEN;
    }

    /* compare remote with local regions */
    r = remote;
    for (i = 0; i < qr->qr_numregions; ++i) {
        foundit = 0;
        l = local;
        for (j = 0; j < localnr; ++j) {
            if (!memcmp(r, l, O2HB_MAX_REGION_NAME_LEN)) {
                foundit = 1;
                break;
            }
            l += O2HB_MAX_REGION_NAME_LEN;
        }
        if (!foundit) {
            status = -EINVAL;
            mlog(ML_ERROR, "Domain %s: Region '%.*s' registered "
                 "in joining node %d but not in local node %d\n",
                 qr->qr_domain, O2HB_MAX_REGION_NAME_LEN, r,
                 qr->qr_node, dlm->node_num);
            goto bail;
        }
        r += O2HB_MAX_REGION_NAME_LEN;
    }

bail:
    return status;
}

static int dlm_send_regions(struct dlm_ctxt *dlm, unsigned long *node_map)
{
    struct dlm_query_region *qr = NULL;
    int status, ret = 0, i;
    char *p;

    if (find_next_bit(node_map, O2NM_MAX_NODES, 0) >= O2NM_MAX_NODES)
        goto bail;

    qr = kzalloc(sizeof(struct dlm_query_region), GFP_KERNEL);
    if (!qr) {
        ret = -ENOMEM;
        mlog_errno(ret);
        goto bail;
    }

    qr->qr_node = dlm->node_num;
    qr->qr_namelen = strlen(dlm->name);
    memcpy(qr->qr_domain, dlm->name, qr->qr_namelen);
    /* if local hb, the numregions will be zero */
    if (o2hb_global_heartbeat_active())
        qr->qr_numregions = o2hb_get_all_regions(qr->qr_regions,
                             O2NM_MAX_REGIONS);

    p = qr->qr_regions;
    for (i = 0; i < qr->qr_numregions; ++i, p += O2HB_MAX_REGION_NAME_LEN)
        mlog(0, "Region %.*s\n", O2HB_MAX_REGION_NAME_LEN, p);

    i = -1;
    while ((i = find_next_bit(node_map, O2NM_MAX_NODES,
                  i + 1)) < O2NM_MAX_NODES) {
        if (i == dlm->node_num)
            continue;

        mlog(0, "Sending regions to node %d\n", i);

        ret = o2net_send_message(DLM_QUERY_REGION, DLM_MOD_KEY, qr,
                     sizeof(struct dlm_query_region),
                     i, &status);
        if (ret >= 0)
            ret = status;
        if (ret) {
            mlog(ML_ERROR, "Region mismatch %d, node %d\n",
                 ret, i);
            break;
        }
    }

bail:
    kfree(qr);
    return ret;
}

static int dlm_query_region_handler(struct o2net_msg *msg, u32 len,
                    void *data, void **ret_data)
{
    struct dlm_query_region *qr;
    struct dlm_ctxt *dlm = NULL;
    char *local = NULL;
    int status = 0;
    int locked = 0;

    qr = (struct dlm_query_region *) msg->buf;

    mlog(0, "Node %u queries hb regions on domain %s\n", qr->qr_node,
         qr->qr_domain);

    /* buffer used in dlm_mast_regions() */
    local = kmalloc(sizeof(qr->qr_regions), GFP_KERNEL);
    if (!local) {
        status = -ENOMEM;
        goto bail;
    }

    status = -EINVAL;

    spin_lock(&dlm_domain_lock);
    dlm = __dlm_lookup_domain_full(qr->qr_domain, qr->qr_namelen);
    if (!dlm) {
        mlog(ML_ERROR, "Node %d queried hb regions on domain %s "
             "before join domain\n", qr->qr_node, qr->qr_domain);
        goto bail;
    }

    spin_lock(&dlm->spinlock);
    locked = 1;
    if (dlm->joining_node != qr->qr_node) {
        mlog(ML_ERROR, "Node %d queried hb regions on domain %s "
             "but joining node is %d\n", qr->qr_node, qr->qr_domain,
             dlm->joining_node);
        goto bail;
    }

    /* Support for global heartbeat was added in 1.1 */
    if (dlm->dlm_locking_proto.pv_major == 1 &&
        dlm->dlm_locking_proto.pv_minor == 0) {
        mlog(ML_ERROR, "Node %d queried hb regions on domain %s "
             "but active dlm protocol is %d.%d\n", qr->qr_node,
             qr->qr_domain, dlm->dlm_locking_proto.pv_major,
             dlm->dlm_locking_proto.pv_minor);
        goto bail;
    }

    status = dlm_match_regions(dlm, qr, local, sizeof(qr->qr_regions));

bail:
    if (locked)
        spin_unlock(&dlm->spinlock);
    spin_unlock(&dlm_domain_lock);

    kfree(local);

    return status;
}

static int dlm_match_nodes(struct dlm_ctxt *dlm, struct dlm_query_nodeinfo *qn)
{
    struct o2nm_node *local;
    struct dlm_node_info *remote;
    int i, j;
    int status = 0;

    for (j = 0; j < qn->qn_numnodes; ++j)
        mlog(0, "Node %3d, %pI4:%u\n", qn->qn_nodes[j].ni_nodenum,
             &(qn->qn_nodes[j].ni_ipv4_address),
             ntohs(qn->qn_nodes[j].ni_ipv4_port));

    for (i = 0; i < O2NM_MAX_NODES && !status; ++i) {
        local = o2nm_get_node_by_num(i);
        remote = NULL;
        for (j = 0; j < qn->qn_numnodes; ++j) {
            if (qn->qn_nodes[j].ni_nodenum == i) {
                remote = &(qn->qn_nodes[j]);
                break;
            }
        }

        if (!local && !remote)
            continue;

        if ((local && !remote) || (!local && remote))
            status = -EINVAL;

        if (!status &&
            ((remote->ni_nodenum != local->nd_num) ||
             (remote->ni_ipv4_port != local->nd_ipv4_port) ||
             (remote->ni_ipv4_address != local->nd_ipv4_address)))
            status = -EINVAL;

        if (status) {
            if (remote && !local)
                mlog(ML_ERROR, "Domain %s: Node %d (%pI4:%u) "
                     "registered in joining node %d but not in "
                     "local node %d\n", qn->qn_domain,
                     remote->ni_nodenum,
                     &(remote->ni_ipv4_address),
                     ntohs(remote->ni_ipv4_port),
                     qn->qn_nodenum, dlm->node_num);
            if (local && !remote)
                mlog(ML_ERROR, "Domain %s: Node %d (%pI4:%u) "
                     "registered in local node %d but not in "
                     "joining node %d\n", qn->qn_domain,
                     local->nd_num, &(local->nd_ipv4_address),
                     ntohs(local->nd_ipv4_port),
                     dlm->node_num, qn->qn_nodenum);
            BUG_ON((!local && !remote));
        }

        if (local)
            o2nm_node_put(local);
    }

    return status;
}

static int dlm_send_nodeinfo(struct dlm_ctxt *dlm, unsigned long *node_map)
{
    struct dlm_query_nodeinfo *qn = NULL;
    struct o2nm_node *node;
    int ret = 0, status, count, i;

    if (find_next_bit(node_map, O2NM_MAX_NODES, 0) >= O2NM_MAX_NODES)
        goto bail;

    qn = kzalloc(sizeof(struct dlm_query_nodeinfo), GFP_KERNEL);
    if (!qn) {
        ret = -ENOMEM;
        mlog_errno(ret);
        goto bail;
    }

    for (i = 0, count = 0; i < O2NM_MAX_NODES; ++i) {
        node = o2nm_get_node_by_num(i);
        if (!node)
            continue;
        qn->qn_nodes[count].ni_nodenum = node->nd_num;
        qn->qn_nodes[count].ni_ipv4_port = node->nd_ipv4_port;
        qn->qn_nodes[count].ni_ipv4_address = node->nd_ipv4_address;
        mlog(0, "Node %3d, %pI4:%u\n", node->nd_num,
             &(node->nd_ipv4_address), ntohs(node->nd_ipv4_port));
        ++count;
        o2nm_node_put(node);
    }

    qn->qn_nodenum = dlm->node_num;
    qn->qn_numnodes = count;
    qn->qn_namelen = strlen(dlm->name);
    memcpy(qn->qn_domain, dlm->name, qn->qn_namelen);

    i = -1;
    while ((i = find_next_bit(node_map, O2NM_MAX_NODES,
                  i + 1)) < O2NM_MAX_NODES) {
        if (i == dlm->node_num)
            continue;

        mlog(0, "Sending nodeinfo to node %d\n", i);

        ret = o2net_send_message(DLM_QUERY_NODEINFO, DLM_MOD_KEY,
                     qn, sizeof(struct dlm_query_nodeinfo),
                     i, &status);
        if (ret >= 0)
            ret = status;
        if (ret) {
            mlog(ML_ERROR, "node mismatch %d, node %d\n", ret, i);
            break;
        }
    }

bail:
    kfree(qn);
    return ret;
}

static int dlm_query_nodeinfo_handler(struct o2net_msg *msg, u32 len,
                      void *data, void **ret_data)
{
    struct dlm_query_nodeinfo *qn;
    struct dlm_ctxt *dlm = NULL;
    int locked = 0, status = -EINVAL;

    qn = (struct dlm_query_nodeinfo *) msg->buf;

    mlog(0, "Node %u queries nodes on domain %s\n", qn->qn_nodenum,
         qn->qn_domain);

    spin_lock(&dlm_domain_lock);
    dlm = __dlm_lookup_domain_full(qn->qn_domain, qn->qn_namelen);
    if (!dlm) {
        mlog(ML_ERROR, "Node %d queried nodes on domain %s before "
             "join domain\n", qn->qn_nodenum, qn->qn_domain);
        goto bail;
    }

    spin_lock(&dlm->spinlock);
    locked = 1;
    if (dlm->joining_node != qn->qn_nodenum) {
        mlog(ML_ERROR, "Node %d queried nodes on domain %s but "
             "joining node is %d\n", qn->qn_nodenum, qn->qn_domain,
             dlm->joining_node);
        goto bail;
    }

    /* Support for node query was added in 1.1 */
    if (dlm->dlm_locking_proto.pv_major == 1 &&
        dlm->dlm_locking_proto.pv_minor == 0) {
        mlog(ML_ERROR, "Node %d queried nodes on domain %s "
             "but active dlm protocol is %d.%d\n", qn->qn_nodenum,
             qn->qn_domain, dlm->dlm_locking_proto.pv_major,
             dlm->dlm_locking_proto.pv_minor);
        goto bail;
    }

    status = dlm_match_nodes(dlm, qn);

bail:
    if (locked)
        spin_unlock(&dlm->spinlock);
    spin_unlock(&dlm_domain_lock);

    return status;
}

static int dlm_cancel_join_handler(struct o2net_msg *msg, u32 len, void *data,
                   void **ret_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(ML_ERROR, "Error %d when sending message %u (key 0x%x) to "
             "node %u\n", status, DLM_CANCEL_JOIN_MSG, DLM_MOD_KEY,
             node);
        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, (unsigned)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_code *response)
{
    int status;
    struct dlm_query_join_request join_msg;
    struct dlm_query_join_packet packet;
    u32 join_resp;

    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);
    join_msg.dlm_proto = dlm->dlm_locking_proto;
    join_msg.fs_proto = dlm->fs_locking_proto;

    /* copy live node map to join message */
    byte_copymap(join_msg.node_map, dlm->live_nodes_map, O2NM_MAX_NODES);

    status = o2net_send_message(DLM_QUERY_JOIN_MSG, DLM_MOD_KEY, &join_msg,
                    sizeof(join_msg), node, &join_resp);
    if (status < 0 && status != -ENOPROTOOPT) {
        mlog(ML_ERROR, "Error %d when sending message %u (key 0x%x) to "
             "node %u\n", status, DLM_QUERY_JOIN_MSG, DLM_MOD_KEY,
             node);
        goto bail;
    }
    dlm_query_join_wire_to_packet(join_resp, &packet);

    /* -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 (packet.code == JOIN_DISALLOW ||
           packet.code == JOIN_OK_NO_MAP) {
        *response = packet.code;
    } else if (packet.code == JOIN_PROTOCOL_MISMATCH) {
        mlog(ML_NOTICE,
             "This node requested DLM locking protocol %u.%u and "
             "filesystem locking protocol %u.%u.  At least one of "
             "the protocol versions on node %d is not compatible, "
             "disconnecting\n",
             dlm->dlm_locking_proto.pv_major,
             dlm->dlm_locking_proto.pv_minor,
             dlm->fs_locking_proto.pv_major,
             dlm->fs_locking_proto.pv_minor,
             node);
        status = -EPROTO;
        *response = packet.code;
    } else if (packet.code == JOIN_OK) {
        *response = packet.code;
        /* Use the same locking protocol as the remote node */
        dlm->dlm_locking_proto.pv_minor = packet.dlm_minor;
        dlm->fs_locking_proto.pv_minor = packet.fs_minor;
        mlog(0,
             "Node %d responds JOIN_OK with DLM locking protocol "
             "%u.%u and fs locking protocol %u.%u\n",
             node,
             dlm->dlm_locking_proto.pv_major,
             dlm->dlm_locking_proto.pv_minor,
             dlm->fs_locking_proto.pv_major,
             dlm->fs_locking_proto.pv_minor);
    } else {
        status = -EINVAL;
        mlog(ML_ERROR, "invalid response %d from node %u\n",
             packet.code, 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(ML_ERROR, "Error %d when sending message %u (key 0x%x) to "
             "node %u\n", status, DLM_ASSERT_JOINED_MSG, DLM_MOD_KEY,
             node);

    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_code 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_code response = JOIN_DISALLOW;

    mlog(0, "%p", dlm);

    ctxt = kzalloc(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);

    /* Support for global heartbeat and node info was added in 1.1 */
    if (dlm->dlm_locking_proto.pv_major > 1 ||
        dlm->dlm_locking_proto.pv_minor > 0) {
        status = dlm_send_nodeinfo(dlm, ctxt->yes_resp_map);
        if (status) {
            mlog_errno(status);
            goto bail;
        }
        status = dlm_send_regions(dlm, ctxt->yes_resp_map);
        if (status) {
            mlog_errno(status);
            goto bail;
        }
    }

    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) {
        printk(KERN_NOTICE "o2dlm: Joining domain %s ", dlm->name);
        __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->name, &dlm->dlm_hb_up);
    o2hb_unregister_callback(dlm->name, &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->name, &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->name, &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, NULL, &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_assert_master_post_handler,
                    &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, NULL, &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, NULL, &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, NULL, &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, NULL, &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, NULL, &dlm->dlm_domain_handlers);
    if (status)
        goto bail;

    status = o2net_register_handler(DLM_DEREF_LOCKRES_MSG, dlm->key,
                    sizeof(struct dlm_deref_lockres),
                    dlm_deref_lockres_handler,
                    dlm, NULL, &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, NULL, &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, NULL, &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, NULL, &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, NULL, &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, NULL, &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, NULL, &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, NULL, &dlm->dlm_domain_handlers);
    if (status)
        goto bail;

    status = o2net_register_handler(DLM_BEGIN_EXIT_DOMAIN_MSG, dlm->key,
                    sizeof(struct dlm_exit_domain),
                    dlm_begin_exit_domain_handler,
                    dlm, NULL, &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;
    unsigned int backoff;
    unsigned int total_backoff = 0;

    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_debug_init(dlm);
    if (status < 0) {
        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;
    }

    dlm->dlm_worker = create_singlethread_workqueue("dlm_wq");
    if (!dlm->dlm_worker) {
        status = -ENOMEM;
        mlog_errno(status);
        goto bail;
    }

    do {
        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. */
#define DLM_JOIN_TIMEOUT_MSECS  90000
        if (status == -EAGAIN) {
            if (signal_pending(current)) {
                status = -ERESTARTSYS;
                goto bail;
            }

            if (total_backoff >
                msecs_to_jiffies(DLM_JOIN_TIMEOUT_MSECS)) {
                status = -ERESTARTSYS;
                mlog(ML_NOTICE, "Timed out joining dlm domain "
                     "%s after %u msecs\n", dlm->name,
                     jiffies_to_msecs(total_backoff));
                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;
            total_backoff += backoff;
            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_debug_shutdown(dlm);
        dlm_complete_thread(dlm);
        dlm_complete_recovery_thread(dlm);
        dlm_destroy_dlm_worker(dlm);
    }

    return status;
}

static struct dlm_ctxt *dlm_alloc_ctxt(const char *domain,
                u32 key)
{
    int i;
    int ret;
    struct dlm_ctxt *dlm = NULL;

    dlm = kzalloc(sizeof(*dlm), GFP_KERNEL);
    if (!dlm) {
        mlog_errno(-ENOMEM);
        goto leave;
    }

    dlm->name = kstrdup(domain, GFP_KERNEL);
    if (dlm->name == NULL) {
        mlog_errno(-ENOMEM);
        kfree(dlm);
        dlm = NULL;
        goto leave;
    }

    dlm->lockres_hash = (struct hlist_head **)dlm_alloc_pagevec(DLM_HASH_PAGES);
    if (!dlm->lockres_hash) {
        mlog_errno(-ENOMEM);
        kfree(dlm->name);
        kfree(dlm);
        dlm = NULL;
        goto leave;
    }

    for (i = 0; i < DLM_HASH_BUCKETS; i++)
        INIT_HLIST_HEAD(dlm_lockres_hash(dlm, i));

    dlm->master_hash = (struct hlist_head **)
                dlm_alloc_pagevec(DLM_HASH_PAGES);
    if (!dlm->master_hash) {
        mlog_errno(-ENOMEM);
        dlm_free_pagevec((void **)dlm->lockres_hash, DLM_HASH_PAGES);
        kfree(dlm->name);
        kfree(dlm);
        dlm = NULL;
        goto leave;
    }

    for (i = 0; i < DLM_HASH_BUCKETS; i++)
        INIT_HLIST_HEAD(dlm_master_hash(dlm, i));

    dlm->key = key;
    dlm->node_num = o2nm_this_node();

    ret = dlm_create_debugfs_subroot(dlm);
    if (ret < 0) {
        dlm_free_pagevec((void **)dlm->master_hash, DLM_HASH_PAGES);
        dlm_free_pagevec((void **)dlm->lockres_hash, DLM_HASH_PAGES);
        kfree(dlm->name);
        kfree(dlm);
        dlm = NULL;
        goto leave;
    }

    spin_lock_init(&dlm->spinlock);
    spin_lock_init(&dlm->master_lock);
    spin_lock_init(&dlm->ast_lock);
    spin_lock_init(&dlm->track_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);
    INIT_LIST_HEAD(&dlm->tracking_list);
    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;
    dlm->dlm_worker = 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->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->res_tot_count, 0);
    atomic_set(&dlm->res_cur_count, 0);
    for (i = 0; i < DLM_MLE_NUM_TYPES; ++i) {
        atomic_set(&dlm->mle_tot_count[i], 0);
        atomic_set(&dlm->mle_cur_count[i], 0);
    }

    spin_lock_init(&dlm->work_lock);
    INIT_LIST_HEAD(&dlm->work_list);
    INIT_WORK(&dlm->dispatched_work, dlm_dispatch_work);

    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;
}

/*
 * Compare a requested locking protocol version against the current one.
 *
 * If the major numbers are different, they are incompatible.
 * If the current minor is greater than the request, they are incompatible.
 * If the current minor is less than or equal to the request, they are
 * compatible, and the requester should run at the current minor version.
 */
static int dlm_protocol_compare(struct dlm_protocol_version *existing,
                struct dlm_protocol_version *request)
{
    if (existing->pv_major != request->pv_major)
        return 1;

    if (existing->pv_minor > request->pv_minor)
        return 1;

    if (existing->pv_minor < request->pv_minor)
        request->pv_minor = existing->pv_minor;

    return 0;
}

/*
 * dlm_register_domain: one-time setup per "domain".
 *
 * The filesystem passes in the requested locking version via proto.
 * If registration was successful, proto will contain the negotiated
 * locking protocol.
 */
struct dlm_ctxt * dlm_register_domain(const char *domain,
                   u32 key,
                   struct dlm_protocol_version *fs_proto)
{
    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;
    }

    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;
        }

        if (dlm_protocol_compare(&dlm->fs_locking_proto, fs_proto)) {
            spin_unlock(&dlm_domain_lock);
            mlog(ML_ERROR,
                 "Requested locking protocol version is not "
                 "compatible with already registered domain "
                 "\"%s\"\n", domain);
            ret = -EPROTO;
            goto leave;
        }

        __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);

    /*
     * Pass the locking protocol version into the join.  If the join
     * succeeds, it will have the negotiated protocol set.
     */
    dlm->dlm_locking_proto = dlm_protocol;
    dlm->fs_locking_proto = *fs_proto;

    ret = dlm_join_domain(dlm);
    if (ret) {
        mlog_errno(ret);
        dlm_put(dlm);
        goto leave;
    }

    /* Tell the caller what locking protocol we negotiated */
    *fs_proto = dlm->fs_locking_proto;

    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, 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, 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, NULL, &dlm_join_handlers);
    if (status)
        goto bail;

    status = o2net_register_handler(DLM_QUERY_REGION, DLM_MOD_KEY,
                    sizeof(struct dlm_query_region),
                    dlm_query_region_handler,
                    NULL, NULL, &dlm_join_handlers);

    if (status)
        goto bail;

    status = o2net_register_handler(DLM_QUERY_NODEINFO, DLM_MOD_KEY,
                    sizeof(struct dlm_query_nodeinfo),
                    dlm_query_nodeinfo_handler,
                    NULL, 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) {
        mlog(ML_ERROR, "Could not create o2dlm_mle slabcache\n");
        goto error;
    }

    status = dlm_init_master_caches();
    if (status) {
        mlog(ML_ERROR, "Could not create o2dlm_lockres and "
             "o2dlm_lockname slabcaches\n");
        goto error;
    }

    status = dlm_init_lock_cache();
    if (status) {
        mlog(ML_ERROR, "Count not create o2dlm_lock slabcache\n");
        goto error;
    }

    status = dlm_register_net_handlers();
    if (status) {
        mlog(ML_ERROR, "Unable to register network handlers\n");
        goto error;
    }

    status = dlm_create_debugfs_root();
    if (status)
        goto error;

    return 0;
error:
    dlm_unregister_net_handlers();
    dlm_destroy_lock_cache();
    dlm_destroy_master_caches();
    dlm_destroy_mle_cache();
    return -1;
}

static void __exit dlm_exit (void)
{
    dlm_destroy_debugfs_root();
    dlm_unregister_net_handlers();
    dlm_destroy_lock_cache();
    dlm_destroy_master_caches();
    dlm_destroy_mle_cache();
}

MODULE_AUTHOR("Oracle");
MODULE_LICENSE("GPL");

module_init(dlm_init);
module_exit(dlm_exit);