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dlmrecovery.c

/* -*- mode: c; c-basic-offset: 8; -*-
 * vim: noexpandtab sw=8 ts=8 sts=0:
 *
 * dlmrecovery.c
 *
 * recovery stuff
 *
 * 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/fs.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/highmem.h>
#include <linux/utsname.h>
#include <linux/init.h>
#include <linux/sysctl.h>
#include <linux/random.h>
#include <linux/blkdev.h>
#include <linux/socket.h>
#include <linux/inet.h>
#include <linux/timer.h>
#include <linux/kthread.h>
#include <linux/delay.h>


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

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

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

static void dlm_do_local_recovery_cleanup(struct dlm_ctxt *dlm, u8 dead_node);

static int dlm_recovery_thread(void *data);
void dlm_complete_recovery_thread(struct dlm_ctxt *dlm);
int dlm_launch_recovery_thread(struct dlm_ctxt *dlm);
void dlm_kick_recovery_thread(struct dlm_ctxt *dlm);
static int dlm_do_recovery(struct dlm_ctxt *dlm);

static int dlm_pick_recovery_master(struct dlm_ctxt *dlm);
static int dlm_remaster_locks(struct dlm_ctxt *dlm, u8 dead_node);
static int dlm_init_recovery_area(struct dlm_ctxt *dlm, u8 dead_node);
static int dlm_request_all_locks(struct dlm_ctxt *dlm,
                         u8 request_from, u8 dead_node);
static void dlm_destroy_recovery_area(struct dlm_ctxt *dlm, u8 dead_node);

static inline int dlm_num_locks_in_lockres(struct dlm_lock_resource *res);
static void dlm_init_migratable_lockres(struct dlm_migratable_lockres *mres,
                              const char *lockname, int namelen,
                              int total_locks, u64 cookie,
                              u8 flags, u8 master);
static int dlm_send_mig_lockres_msg(struct dlm_ctxt *dlm,
                            struct dlm_migratable_lockres *mres,
                            u8 send_to,
                            struct dlm_lock_resource *res,
                            int total_locks);
static int dlm_process_recovery_data(struct dlm_ctxt *dlm,
                             struct dlm_lock_resource *res,
                             struct dlm_migratable_lockres *mres);
static int dlm_send_finalize_reco_message(struct dlm_ctxt *dlm);
static int dlm_send_all_done_msg(struct dlm_ctxt *dlm,
                         u8 dead_node, u8 send_to);
static int dlm_send_begin_reco_message(struct dlm_ctxt *dlm, u8 dead_node);
static void dlm_move_reco_locks_to_list(struct dlm_ctxt *dlm,
                              struct list_head *list, u8 dead_node);
static void dlm_finish_local_lockres_recovery(struct dlm_ctxt *dlm,
                                    u8 dead_node, u8 new_master);
static void dlm_reco_ast(void *astdata);
static void dlm_reco_bast(void *astdata, int blocked_type);
static void dlm_reco_unlock_ast(void *astdata, enum dlm_status st);
static void dlm_request_all_locks_worker(struct dlm_work_item *item,
                               void *data);
static void dlm_mig_lockres_worker(struct dlm_work_item *item, void *data);
static int dlm_lockres_master_requery(struct dlm_ctxt *dlm,
                              struct dlm_lock_resource *res,
                              u8 *real_master);

static u64 dlm_get_next_mig_cookie(void);

static DEFINE_SPINLOCK(dlm_reco_state_lock);
static DEFINE_SPINLOCK(dlm_mig_cookie_lock);
static u64 dlm_mig_cookie = 1;

static u64 dlm_get_next_mig_cookie(void)
{
      u64 c;
      spin_lock(&dlm_mig_cookie_lock);
      c = dlm_mig_cookie;
      if (dlm_mig_cookie == (~0ULL))
            dlm_mig_cookie = 1;
      else
            dlm_mig_cookie++;
      spin_unlock(&dlm_mig_cookie_lock);
      return c;
}

static inline void dlm_set_reco_dead_node(struct dlm_ctxt *dlm,
                                u8 dead_node)
{
      assert_spin_locked(&dlm->spinlock);
      if (dlm->reco.dead_node != dead_node)
            mlog(0, "%s: changing dead_node from %u to %u\n",
                 dlm->name, dlm->reco.dead_node, dead_node);
      dlm->reco.dead_node = dead_node;
}

static inline void dlm_set_reco_master(struct dlm_ctxt *dlm,
                               u8 master)
{
      assert_spin_locked(&dlm->spinlock);
      mlog(0, "%s: changing new_master from %u to %u\n",
           dlm->name, dlm->reco.new_master, master);
      dlm->reco.new_master = master;
}

static inline void __dlm_reset_recovery(struct dlm_ctxt *dlm)
{
      assert_spin_locked(&dlm->spinlock);
      clear_bit(dlm->reco.dead_node, dlm->recovery_map);
      dlm_set_reco_dead_node(dlm, O2NM_INVALID_NODE_NUM);
      dlm_set_reco_master(dlm, O2NM_INVALID_NODE_NUM);
}

static inline void dlm_reset_recovery(struct dlm_ctxt *dlm)
{
      spin_lock(&dlm->spinlock);
      __dlm_reset_recovery(dlm);
      spin_unlock(&dlm->spinlock);
}

/* Worker function used during recovery. */
void dlm_dispatch_work(struct work_struct *work)
{
      struct dlm_ctxt *dlm =
            container_of(work, struct dlm_ctxt, dispatched_work);
      LIST_HEAD(tmp_list);
      struct dlm_work_item *item, *next;
      dlm_workfunc_t *workfunc;
      int tot=0;

      spin_lock(&dlm->work_lock);
      list_splice_init(&dlm->work_list, &tmp_list);
      spin_unlock(&dlm->work_lock);

      list_for_each_entry(item, &tmp_list, list) {
            tot++;
      }
      mlog(0, "%s: work thread has %d work items\n", dlm->name, tot);

      list_for_each_entry_safe(item, next, &tmp_list, list) {
            workfunc = item->func;
            list_del_init(&item->list);

            /* already have ref on dlm to avoid having
             * it disappear.  just double-check. */
            BUG_ON(item->dlm != dlm);

            /* this is allowed to sleep and
             * call network stuff */
            workfunc(item, item->data);

            dlm_put(dlm);
            kfree(item);
      }
}

/*
 * RECOVERY THREAD
 */

void dlm_kick_recovery_thread(struct dlm_ctxt *dlm)
{
      /* wake the recovery thread
       * this will wake the reco thread in one of three places
       * 1) sleeping with no recovery happening
       * 2) sleeping with recovery mastered elsewhere
       * 3) recovery mastered here, waiting on reco data */

      wake_up(&dlm->dlm_reco_thread_wq);
}

/* Launch the recovery thread */
int dlm_launch_recovery_thread(struct dlm_ctxt *dlm)
{
      mlog(0, "starting dlm recovery thread...\n");

      dlm->dlm_reco_thread_task = kthread_run(dlm_recovery_thread, dlm,
                                    "dlm_reco_thread");
      if (IS_ERR(dlm->dlm_reco_thread_task)) {
            mlog_errno(PTR_ERR(dlm->dlm_reco_thread_task));
            dlm->dlm_reco_thread_task = NULL;
            return -EINVAL;
      }

      return 0;
}

void dlm_complete_recovery_thread(struct dlm_ctxt *dlm)
{
      if (dlm->dlm_reco_thread_task) {
            mlog(0, "waiting for dlm recovery thread to exit\n");
            kthread_stop(dlm->dlm_reco_thread_task);
            dlm->dlm_reco_thread_task = NULL;
      }
}



/*
 * this is lame, but here's how recovery works...
 * 1) all recovery threads cluster wide will work on recovering
 *    ONE node at a time
 * 2) negotiate who will take over all the locks for the dead node.
 *    thats right... ALL the locks.
 * 3) once a new master is chosen, everyone scans all locks
 *    and moves aside those mastered by the dead guy
 * 4) each of these locks should be locked until recovery is done
 * 5) the new master collects up all of secondary lock queue info
 *    one lock at a time, forcing each node to communicate back
 *    before continuing
 * 6) each secondary lock queue responds with the full known lock info
 * 7) once the new master has run all its locks, it sends a ALLDONE!
 *    message to everyone
 * 8) upon receiving this message, the secondary queue node unlocks
 *    and responds to the ALLDONE
 * 9) once the new master gets responses from everyone, he unlocks
 *    everything and recovery for this dead node is done
 *10) go back to 2) while there are still dead nodes
 *
 */

static void dlm_print_reco_node_status(struct dlm_ctxt *dlm)
{
      struct dlm_reco_node_data *ndata;
      struct dlm_lock_resource *res;

      mlog(ML_NOTICE, "%s(%d): recovery info, state=%s, dead=%u, master=%u\n",
           dlm->name, task_pid_nr(dlm->dlm_reco_thread_task),
           dlm->reco.state & DLM_RECO_STATE_ACTIVE ? "ACTIVE" : "inactive",
           dlm->reco.dead_node, dlm->reco.new_master);

      list_for_each_entry(ndata, &dlm->reco.node_data, list) {
            char *st = "unknown";
            switch (ndata->state) {
                  case DLM_RECO_NODE_DATA_INIT:
                        st = "init";
                        break;
                  case DLM_RECO_NODE_DATA_REQUESTING:
                        st = "requesting";
                        break;
                  case DLM_RECO_NODE_DATA_DEAD:
                        st = "dead";
                        break;
                  case DLM_RECO_NODE_DATA_RECEIVING:
                        st = "receiving";
                        break;
                  case DLM_RECO_NODE_DATA_REQUESTED:
                        st = "requested";
                        break;
                  case DLM_RECO_NODE_DATA_DONE:
                        st = "done";
                        break;
                  case DLM_RECO_NODE_DATA_FINALIZE_SENT:
                        st = "finalize-sent";
                        break;
                  default:
                        st = "bad";
                        break;
            }
            mlog(ML_NOTICE, "%s: reco state, node %u, state=%s\n",
                 dlm->name, ndata->node_num, st);
      }
      list_for_each_entry(res, &dlm->reco.resources, recovering) {
            mlog(ML_NOTICE, "%s: lockres %.*s on recovering list\n",
                 dlm->name, res->lockname.len, res->lockname.name);
      }
}

#define DLM_RECO_THREAD_TIMEOUT_MS (5 * 1000)

static int dlm_recovery_thread(void *data)
{
      int status;
      struct dlm_ctxt *dlm = data;
      unsigned long timeout = msecs_to_jiffies(DLM_RECO_THREAD_TIMEOUT_MS);

      mlog(0, "dlm thread running for %s...\n", dlm->name);

      while (!kthread_should_stop()) {
            if (dlm_joined(dlm)) {
                  status = dlm_do_recovery(dlm);
                  if (status == -EAGAIN) {
                        /* do not sleep, recheck immediately. */
                        continue;
                  }
                  if (status < 0)
                        mlog_errno(status);
            }

            wait_event_interruptible_timeout(dlm->dlm_reco_thread_wq,
                                     kthread_should_stop(),
                                     timeout);
      }

      mlog(0, "quitting DLM recovery thread\n");
      return 0;
}

/* returns true when the recovery master has contacted us */
static int dlm_reco_master_ready(struct dlm_ctxt *dlm)
{
      int ready;
      spin_lock(&dlm->spinlock);
      ready = (dlm->reco.new_master != O2NM_INVALID_NODE_NUM);
      spin_unlock(&dlm->spinlock);
      return ready;
}

/* returns true if node is no longer in the domain
 * could be dead or just not joined */
int dlm_is_node_dead(struct dlm_ctxt *dlm, u8 node)
{
      int dead;
      spin_lock(&dlm->spinlock);
      dead = !test_bit(node, dlm->domain_map);
      spin_unlock(&dlm->spinlock);
      return dead;
}

/* returns true if node is no longer in the domain
 * could be dead or just not joined */
static int dlm_is_node_recovered(struct dlm_ctxt *dlm, u8 node)
{
      int recovered;
      spin_lock(&dlm->spinlock);
      recovered = !test_bit(node, dlm->recovery_map);
      spin_unlock(&dlm->spinlock);
      return recovered;
}


int dlm_wait_for_node_death(struct dlm_ctxt *dlm, u8 node, int timeout)
{
      if (timeout) {
            mlog(ML_NOTICE, "%s: waiting %dms for notification of "
                 "death of node %u\n", dlm->name, timeout, node);
            wait_event_timeout(dlm->dlm_reco_thread_wq,
                     dlm_is_node_dead(dlm, node),
                     msecs_to_jiffies(timeout));
      } else {
            mlog(ML_NOTICE, "%s: waiting indefinitely for notification "
                 "of death of node %u\n", dlm->name, node);
            wait_event(dlm->dlm_reco_thread_wq,
                     dlm_is_node_dead(dlm, node));
      }
      /* for now, return 0 */
      return 0;
}

int dlm_wait_for_node_recovery(struct dlm_ctxt *dlm, u8 node, int timeout)
{
      if (timeout) {
            mlog(0, "%s: waiting %dms for notification of "
                 "recovery of node %u\n", dlm->name, timeout, node);
            wait_event_timeout(dlm->dlm_reco_thread_wq,
                     dlm_is_node_recovered(dlm, node),
                     msecs_to_jiffies(timeout));
      } else {
            mlog(0, "%s: waiting indefinitely for notification "
                 "of recovery of node %u\n", dlm->name, node);
            wait_event(dlm->dlm_reco_thread_wq,
                     dlm_is_node_recovered(dlm, node));
      }
      /* for now, return 0 */
      return 0;
}

/* callers of the top-level api calls (dlmlock/dlmunlock) should
 * block on the dlm->reco.event when recovery is in progress.
 * the dlm recovery thread will set this state when it begins
 * recovering a dead node (as the new master or not) and clear
 * the state and wake as soon as all affected lock resources have
 * been marked with the RECOVERY flag */
static int dlm_in_recovery(struct dlm_ctxt *dlm)
{
      int in_recovery;
      spin_lock(&dlm->spinlock);
      in_recovery = !!(dlm->reco.state & DLM_RECO_STATE_ACTIVE);
      spin_unlock(&dlm->spinlock);
      return in_recovery;
}


void dlm_wait_for_recovery(struct dlm_ctxt *dlm)
{
      if (dlm_in_recovery(dlm)) {
            mlog(0, "%s: reco thread %d in recovery: "
                 "state=%d, master=%u, dead=%u\n",
                 dlm->name, task_pid_nr(dlm->dlm_reco_thread_task),
                 dlm->reco.state, dlm->reco.new_master,
                 dlm->reco.dead_node);
      }
      wait_event(dlm->reco.event, !dlm_in_recovery(dlm));
}

static void dlm_begin_recovery(struct dlm_ctxt *dlm)
{
      spin_lock(&dlm->spinlock);
      BUG_ON(dlm->reco.state & DLM_RECO_STATE_ACTIVE);
      dlm->reco.state |= DLM_RECO_STATE_ACTIVE;
      spin_unlock(&dlm->spinlock);
}

static void dlm_end_recovery(struct dlm_ctxt *dlm)
{
      spin_lock(&dlm->spinlock);
      BUG_ON(!(dlm->reco.state & DLM_RECO_STATE_ACTIVE));
      dlm->reco.state &= ~DLM_RECO_STATE_ACTIVE;
      spin_unlock(&dlm->spinlock);
      wake_up(&dlm->reco.event);
}

static int dlm_do_recovery(struct dlm_ctxt *dlm)
{
      int status = 0;
      int ret;

      spin_lock(&dlm->spinlock);

      /* check to see if the new master has died */
      if (dlm->reco.new_master != O2NM_INVALID_NODE_NUM &&
          test_bit(dlm->reco.new_master, dlm->recovery_map)) {
            mlog(0, "new master %u died while recovering %u!\n",
                 dlm->reco.new_master, dlm->reco.dead_node);
            /* unset the new_master, leave dead_node */
            dlm_set_reco_master(dlm, O2NM_INVALID_NODE_NUM);
      }

      /* select a target to recover */
      if (dlm->reco.dead_node == O2NM_INVALID_NODE_NUM) {
            int bit;

            bit = find_next_bit (dlm->recovery_map, O2NM_MAX_NODES+1, 0);
            if (bit >= O2NM_MAX_NODES || bit < 0)
                  dlm_set_reco_dead_node(dlm, O2NM_INVALID_NODE_NUM);
            else
                  dlm_set_reco_dead_node(dlm, bit);
      } else if (!test_bit(dlm->reco.dead_node, dlm->recovery_map)) {
            /* BUG? */
            mlog(ML_ERROR, "dead_node %u no longer in recovery map!\n",
                 dlm->reco.dead_node);
            dlm_set_reco_dead_node(dlm, O2NM_INVALID_NODE_NUM);
      }

      if (dlm->reco.dead_node == O2NM_INVALID_NODE_NUM) {
            // mlog(0, "nothing to recover!  sleeping now!\n");
            spin_unlock(&dlm->spinlock);
            /* return to main thread loop and sleep. */
            return 0;
      }
      mlog(0, "%s(%d):recovery thread found node %u in the recovery map!\n",
           dlm->name, task_pid_nr(dlm->dlm_reco_thread_task),
           dlm->reco.dead_node);
      spin_unlock(&dlm->spinlock);

      /* take write barrier */
      /* (stops the list reshuffling thread, proxy ast handling) */
      dlm_begin_recovery(dlm);

      if (dlm->reco.new_master == dlm->node_num)
            goto master_here;

      if (dlm->reco.new_master == O2NM_INVALID_NODE_NUM) {
            /* choose a new master, returns 0 if this node
             * is the master, -EEXIST if it's another node.
             * this does not return until a new master is chosen
             * or recovery completes entirely. */
            ret = dlm_pick_recovery_master(dlm);
            if (!ret) {
                  /* already notified everyone.  go. */
                  goto master_here;
            }
            mlog(0, "another node will master this recovery session.\n");
      }
      mlog(0, "dlm=%s (%d), new_master=%u, this node=%u, dead_node=%u\n",
           dlm->name, task_pid_nr(dlm->dlm_reco_thread_task), dlm->reco.new_master,
           dlm->node_num, dlm->reco.dead_node);

      /* it is safe to start everything back up here
       * because all of the dead node's lock resources
       * have been marked as in-recovery */
      dlm_end_recovery(dlm);

      /* sleep out in main dlm_recovery_thread loop. */
      return 0;

master_here:
      mlog(0, "(%d) mastering recovery of %s:%u here(this=%u)!\n",
           task_pid_nr(dlm->dlm_reco_thread_task),
           dlm->name, dlm->reco.dead_node, dlm->node_num);

      status = dlm_remaster_locks(dlm, dlm->reco.dead_node);
      if (status < 0) {
            /* we should never hit this anymore */
            mlog(ML_ERROR, "error %d remastering locks for node %u, "
                 "retrying.\n", status, dlm->reco.dead_node);
            /* yield a bit to allow any final network messages
             * to get handled on remaining nodes */
            msleep(100);
      } else {
            /* success!  see if any other nodes need recovery */
            mlog(0, "DONE mastering recovery of %s:%u here(this=%u)!\n",
                 dlm->name, dlm->reco.dead_node, dlm->node_num);
            dlm_reset_recovery(dlm);
      }
      dlm_end_recovery(dlm);

      /* continue and look for another dead node */
      return -EAGAIN;
}

static int dlm_remaster_locks(struct dlm_ctxt *dlm, u8 dead_node)
{
      int status = 0;
      struct dlm_reco_node_data *ndata;
      int all_nodes_done;
      int destroy = 0;
      int pass = 0;

      do {
            /* we have become recovery master.  there is no escaping
             * this, so just keep trying until we get it. */
            status = dlm_init_recovery_area(dlm, dead_node);
            if (status < 0) {
                  mlog(ML_ERROR, "%s: failed to alloc recovery area, "
                       "retrying\n", dlm->name);
                  msleep(1000);
            }
      } while (status != 0);

      /* safe to access the node data list without a lock, since this
       * process is the only one to change the list */
      list_for_each_entry(ndata, &dlm->reco.node_data, list) {
            BUG_ON(ndata->state != DLM_RECO_NODE_DATA_INIT);
            ndata->state = DLM_RECO_NODE_DATA_REQUESTING;

            mlog(0, "requesting lock info from node %u\n",
                 ndata->node_num);

            if (ndata->node_num == dlm->node_num) {
                  ndata->state = DLM_RECO_NODE_DATA_DONE;
                  continue;
            }

            do {
                  status = dlm_request_all_locks(dlm, ndata->node_num,
                                           dead_node);
                  if (status < 0) {
                        mlog_errno(status);
                        if (dlm_is_host_down(status)) {
                              /* node died, ignore it for recovery */
                              status = 0;
                              ndata->state = DLM_RECO_NODE_DATA_DEAD;
                              /* wait for the domain map to catch up
                               * with the network state. */
                              wait_event_timeout(dlm->dlm_reco_thread_wq,
                                             dlm_is_node_dead(dlm,
                                                ndata->node_num),
                                             msecs_to_jiffies(1000));
                              mlog(0, "waited 1 sec for %u, "
                                   "dead? %s\n", ndata->node_num,
                                   dlm_is_node_dead(dlm, ndata->node_num) ?
                                   "yes" : "no");
                        } else {
                              /* -ENOMEM on the other node */
                              mlog(0, "%s: node %u returned "
                                   "%d during recovery, retrying "
                                   "after a short wait\n",
                                   dlm->name, ndata->node_num,
                                   status);
                              msleep(100);
                        }
                  }
            } while (status != 0);

            spin_lock(&dlm_reco_state_lock);
            switch (ndata->state) {
                  case DLM_RECO_NODE_DATA_INIT:
                  case DLM_RECO_NODE_DATA_FINALIZE_SENT:
                  case DLM_RECO_NODE_DATA_REQUESTED:
                        BUG();
                        break;
                  case DLM_RECO_NODE_DATA_DEAD:
                        mlog(0, "node %u died after requesting "
                             "recovery info for node %u\n",
                             ndata->node_num, dead_node);
                        /* fine.  don't need this node's info.
                         * continue without it. */
                        break;
                  case DLM_RECO_NODE_DATA_REQUESTING:
                        ndata->state = DLM_RECO_NODE_DATA_REQUESTED;
                        mlog(0, "now receiving recovery data from "
                             "node %u for dead node %u\n",
                             ndata->node_num, dead_node);
                        break;
                  case DLM_RECO_NODE_DATA_RECEIVING:
                        mlog(0, "already receiving recovery data from "
                             "node %u for dead node %u\n",
                             ndata->node_num, dead_node);
                        break;
                  case DLM_RECO_NODE_DATA_DONE:
                        mlog(0, "already DONE receiving recovery data "
                             "from node %u for dead node %u\n",
                             ndata->node_num, dead_node);
                        break;
            }
            spin_unlock(&dlm_reco_state_lock);
      }

      mlog(0, "done requesting all lock info\n");

      /* nodes should be sending reco data now
       * just need to wait */

      while (1) {
            /* check all the nodes now to see if we are
             * done, or if anyone died */
            all_nodes_done = 1;
            spin_lock(&dlm_reco_state_lock);
            list_for_each_entry(ndata, &dlm->reco.node_data, list) {
                  mlog(0, "checking recovery state of node %u\n",
                       ndata->node_num);
                  switch (ndata->state) {
                        case DLM_RECO_NODE_DATA_INIT:
                        case DLM_RECO_NODE_DATA_REQUESTING:
                              mlog(ML_ERROR, "bad ndata state for "
                                   "node %u: state=%d\n",
                                   ndata->node_num, ndata->state);
                              BUG();
                              break;
                        case DLM_RECO_NODE_DATA_DEAD:
                              mlog(0, "node %u died after "
                                   "requesting recovery info for "
                                   "node %u\n", ndata->node_num,
                                   dead_node);
                              break;
                        case DLM_RECO_NODE_DATA_RECEIVING:
                        case DLM_RECO_NODE_DATA_REQUESTED:
                              mlog(0, "%s: node %u still in state %s\n",
                                   dlm->name, ndata->node_num,
                                   ndata->state==DLM_RECO_NODE_DATA_RECEIVING ?
                                   "receiving" : "requested");
                              all_nodes_done = 0;
                              break;
                        case DLM_RECO_NODE_DATA_DONE:
                              mlog(0, "%s: node %u state is done\n",
                                   dlm->name, ndata->node_num);
                              break;
                        case DLM_RECO_NODE_DATA_FINALIZE_SENT:
                              mlog(0, "%s: node %u state is finalize\n",
                                   dlm->name, ndata->node_num);
                              break;
                  }
            }
            spin_unlock(&dlm_reco_state_lock);

            mlog(0, "pass #%d, all_nodes_done?: %s\n", ++pass,
                 all_nodes_done?"yes":"no");
            if (all_nodes_done) {
                  int ret;

                  /* all nodes are now in DLM_RECO_NODE_DATA_DONE state
                   * just send a finalize message to everyone and
                   * clean up */
                  mlog(0, "all nodes are done! send finalize\n");
                  ret = dlm_send_finalize_reco_message(dlm);
                  if (ret < 0)
                        mlog_errno(ret);

                  spin_lock(&dlm->spinlock);
                  dlm_finish_local_lockres_recovery(dlm, dead_node,
                                            dlm->node_num);
                  spin_unlock(&dlm->spinlock);
                  mlog(0, "should be done with recovery!\n");

                  mlog(0, "finishing recovery of %s at %lu, "
                       "dead=%u, this=%u, new=%u\n", dlm->name,
                       jiffies, dlm->reco.dead_node,
                       dlm->node_num, dlm->reco.new_master);
                  destroy = 1;
                  status = 0;
                  /* rescan everything marked dirty along the way */
                  dlm_kick_thread(dlm, NULL);
                  break;
            }
            /* wait to be signalled, with periodic timeout
             * to check for node death */
            wait_event_interruptible_timeout(dlm->dlm_reco_thread_wq,
                               kthread_should_stop(),
                               msecs_to_jiffies(DLM_RECO_THREAD_TIMEOUT_MS));

      }

      if (destroy)
            dlm_destroy_recovery_area(dlm, dead_node);

      mlog_exit(status);
      return status;
}

static int dlm_init_recovery_area(struct dlm_ctxt *dlm, u8 dead_node)
{
      int num=0;
      struct dlm_reco_node_data *ndata;

      spin_lock(&dlm->spinlock);
      memcpy(dlm->reco.node_map, dlm->domain_map, sizeof(dlm->domain_map));
      /* nodes can only be removed (by dying) after dropping
       * this lock, and death will be trapped later, so this should do */
      spin_unlock(&dlm->spinlock);

      while (1) {
            num = find_next_bit (dlm->reco.node_map, O2NM_MAX_NODES, num);
            if (num >= O2NM_MAX_NODES) {
                  break;
            }
            BUG_ON(num == dead_node);

            ndata = kzalloc(sizeof(*ndata), GFP_NOFS);
            if (!ndata) {
                  dlm_destroy_recovery_area(dlm, dead_node);
                  return -ENOMEM;
            }
            ndata->node_num = num;
            ndata->state = DLM_RECO_NODE_DATA_INIT;
            spin_lock(&dlm_reco_state_lock);
            list_add_tail(&ndata->list, &dlm->reco.node_data);
            spin_unlock(&dlm_reco_state_lock);
            num++;
      }

      return 0;
}

static void dlm_destroy_recovery_area(struct dlm_ctxt *dlm, u8 dead_node)
{
      struct dlm_reco_node_data *ndata, *next;
      LIST_HEAD(tmplist);

      spin_lock(&dlm_reco_state_lock);
      list_splice_init(&dlm->reco.node_data, &tmplist);
      spin_unlock(&dlm_reco_state_lock);

      list_for_each_entry_safe(ndata, next, &tmplist, list) {
            list_del_init(&ndata->list);
            kfree(ndata);
      }
}

static int dlm_request_all_locks(struct dlm_ctxt *dlm, u8 request_from,
                         u8 dead_node)
{
      struct dlm_lock_request lr;
      enum dlm_status ret;

      mlog(0, "\n");


      mlog(0, "dlm_request_all_locks: dead node is %u, sending request "
              "to %u\n", dead_node, request_from);

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

      // send message
      ret = DLM_NOLOCKMGR;
      ret = o2net_send_message(DLM_LOCK_REQUEST_MSG, dlm->key,
                         &lr, sizeof(lr), request_from, NULL);

      /* negative status is handled by caller */
      if (ret < 0)
            mlog_errno(ret);

      // return from here, then
      // sleep until all received or error
      return ret;

}

int dlm_request_all_locks_handler(struct o2net_msg *msg, u32 len, void *data,
                          void **ret_data)
{
      struct dlm_ctxt *dlm = data;
      struct dlm_lock_request *lr = (struct dlm_lock_request *)msg->buf;
      char *buf = NULL;
      struct dlm_work_item *item = NULL;

      if (!dlm_grab(dlm))
            return -EINVAL;

      if (lr->dead_node != dlm->reco.dead_node) {
            mlog(ML_ERROR, "%s: node %u sent dead_node=%u, but local "
                 "dead_node is %u\n", dlm->name, lr->node_idx,
                 lr->dead_node, dlm->reco.dead_node);
            dlm_print_reco_node_status(dlm);
            /* this is a hack */
            dlm_put(dlm);
            return -ENOMEM;
      }
      BUG_ON(lr->dead_node != dlm->reco.dead_node);

      item = kzalloc(sizeof(*item), GFP_NOFS);
      if (!item) {
            dlm_put(dlm);
            return -ENOMEM;
      }

      /* this will get freed by dlm_request_all_locks_worker */
      buf = (char *) __get_free_page(GFP_NOFS);
      if (!buf) {
            kfree(item);
            dlm_put(dlm);
            return -ENOMEM;
      }

      /* queue up work for dlm_request_all_locks_worker */
      dlm_grab(dlm);  /* get an extra ref for the work item */
      dlm_init_work_item(dlm, item, dlm_request_all_locks_worker, buf);
      item->u.ral.reco_master = lr->node_idx;
      item->u.ral.dead_node = lr->dead_node;
      spin_lock(&dlm->work_lock);
      list_add_tail(&item->list, &dlm->work_list);
      spin_unlock(&dlm->work_lock);
      queue_work(dlm->dlm_worker, &dlm->dispatched_work);

      dlm_put(dlm);
      return 0;
}

static void dlm_request_all_locks_worker(struct dlm_work_item *item, void *data)
{
      struct dlm_migratable_lockres *mres;
      struct dlm_lock_resource *res;
      struct dlm_ctxt *dlm;
      LIST_HEAD(resources);
      int ret;
      u8 dead_node, reco_master;
      int skip_all_done = 0;

      dlm = item->dlm;
      dead_node = item->u.ral.dead_node;
      reco_master = item->u.ral.reco_master;
      mres = (struct dlm_migratable_lockres *)data;

      mlog(0, "%s: recovery worker started, dead=%u, master=%u\n",
           dlm->name, dead_node, reco_master);

      if (dead_node != dlm->reco.dead_node ||
          reco_master != dlm->reco.new_master) {
            /* worker could have been created before the recovery master
             * died.  if so, do not continue, but do not error. */
            if (dlm->reco.new_master == O2NM_INVALID_NODE_NUM) {
                  mlog(ML_NOTICE, "%s: will not send recovery state, "
                       "recovery master %u died, thread=(dead=%u,mas=%u)"
                       " current=(dead=%u,mas=%u)\n", dlm->name,
                       reco_master, dead_node, reco_master,
                       dlm->reco.dead_node, dlm->reco.new_master);
            } else {
                  mlog(ML_NOTICE, "%s: reco state invalid: reco(dead=%u, "
                       "master=%u), request(dead=%u, master=%u)\n",
                       dlm->name, dlm->reco.dead_node,
                       dlm->reco.new_master, dead_node, reco_master);
            }
            goto leave;
      }

      /* lock resources should have already been moved to the
       * dlm->reco.resources list.  now move items from that list
       * to a temp list if the dead owner matches.  note that the
       * whole cluster recovers only one node at a time, so we
       * can safely move UNKNOWN lock resources for each recovery
       * session. */
      dlm_move_reco_locks_to_list(dlm, &resources, dead_node);

      /* now we can begin blasting lockreses without the dlm lock */

      /* any errors returned will be due to the new_master dying,
       * the dlm_reco_thread should detect this */
      list_for_each_entry(res, &resources, recovering) {
            ret = dlm_send_one_lockres(dlm, res, mres, reco_master,
                              DLM_MRES_RECOVERY);
            if (ret < 0) {
                  mlog(ML_ERROR, "%s: node %u went down while sending "
                       "recovery state for dead node %u, ret=%d\n", dlm->name,
                       reco_master, dead_node, ret);
                  skip_all_done = 1;
                  break;
            }
      }

      /* move the resources back to the list */
      spin_lock(&dlm->spinlock);
      list_splice_init(&resources, &dlm->reco.resources);
      spin_unlock(&dlm->spinlock);

      if (!skip_all_done) {
            ret = dlm_send_all_done_msg(dlm, dead_node, reco_master);
            if (ret < 0) {
                  mlog(ML_ERROR, "%s: node %u went down while sending "
                       "recovery all-done for dead node %u, ret=%d\n",
                       dlm->name, reco_master, dead_node, ret);
            }
      }
leave:
      free_page((unsigned long)data);
}


static int dlm_send_all_done_msg(struct dlm_ctxt *dlm, u8 dead_node, u8 send_to)
{
      int ret, tmpret;
      struct dlm_reco_data_done done_msg;

      memset(&done_msg, 0, sizeof(done_msg));
      done_msg.node_idx = dlm->node_num;
      done_msg.dead_node = dead_node;
      mlog(0, "sending DATA DONE message to %u, "
           "my node=%u, dead node=%u\n", send_to, done_msg.node_idx,
           done_msg.dead_node);

      ret = o2net_send_message(DLM_RECO_DATA_DONE_MSG, dlm->key, &done_msg,
                         sizeof(done_msg), send_to, &tmpret);
      if (ret < 0) {
            if (!dlm_is_host_down(ret)) {
                  mlog_errno(ret);
                  mlog(ML_ERROR, "%s: unknown error sending data-done "
                       "to %u\n", dlm->name, send_to);
                  BUG();
            }
      } else
            ret = tmpret;
      return ret;
}


int dlm_reco_data_done_handler(struct o2net_msg *msg, u32 len, void *data,
                         void **ret_data)
{
      struct dlm_ctxt *dlm = data;
      struct dlm_reco_data_done *done = (struct dlm_reco_data_done *)msg->buf;
      struct dlm_reco_node_data *ndata = NULL;
      int ret = -EINVAL;

      if (!dlm_grab(dlm))
            return -EINVAL;

      mlog(0, "got DATA DONE: dead_node=%u, reco.dead_node=%u, "
           "node_idx=%u, this node=%u\n", done->dead_node,
           dlm->reco.dead_node, done->node_idx, dlm->node_num);

      mlog_bug_on_msg((done->dead_node != dlm->reco.dead_node),
                  "Got DATA DONE: dead_node=%u, reco.dead_node=%u, "
                  "node_idx=%u, this node=%u\n", done->dead_node,
                  dlm->reco.dead_node, done->node_idx, dlm->node_num);

      spin_lock(&dlm_reco_state_lock);
      list_for_each_entry(ndata, &dlm->reco.node_data, list) {
            if (ndata->node_num != done->node_idx)
                  continue;

            switch (ndata->state) {
                  /* should have moved beyond INIT but not to FINALIZE yet */
                  case DLM_RECO_NODE_DATA_INIT:
                  case DLM_RECO_NODE_DATA_DEAD:
                  case DLM_RECO_NODE_DATA_FINALIZE_SENT:
                        mlog(ML_ERROR, "bad ndata state for node %u:"
                             " state=%d\n", ndata->node_num,
                             ndata->state);
                        BUG();
                        break;
                  /* these states are possible at this point, anywhere along
                   * the line of recovery */
                  case DLM_RECO_NODE_DATA_DONE:
                  case DLM_RECO_NODE_DATA_RECEIVING:
                  case DLM_RECO_NODE_DATA_REQUESTED:
                  case DLM_RECO_NODE_DATA_REQUESTING:
                        mlog(0, "node %u is DONE sending "
                                "recovery data!\n",
                                ndata->node_num);

                        ndata->state = DLM_RECO_NODE_DATA_DONE;
                        ret = 0;
                        break;
            }
      }
      spin_unlock(&dlm_reco_state_lock);

      /* wake the recovery thread, some node is done */
      if (!ret)
            dlm_kick_recovery_thread(dlm);

      if (ret < 0)
            mlog(ML_ERROR, "failed to find recovery node data for node "
                 "%u\n", done->node_idx);
      dlm_put(dlm);

      mlog(0, "leaving reco data done handler, ret=%d\n", ret);
      return ret;
}

static void dlm_move_reco_locks_to_list(struct dlm_ctxt *dlm,
                              struct list_head *list,
                                    u8 dead_node)
{
      struct dlm_lock_resource *res, *next;
      struct dlm_lock *lock;

      spin_lock(&dlm->spinlock);
      list_for_each_entry_safe(res, next, &dlm->reco.resources, recovering) {
            /* always prune any $RECOVERY entries for dead nodes,
             * otherwise hangs can occur during later recovery */
            if (dlm_is_recovery_lock(res->lockname.name,
                               res->lockname.len)) {
                  spin_lock(&res->spinlock);
                  list_for_each_entry(lock, &res->granted, list) {
                        if (lock->ml.node == dead_node) {
                              mlog(0, "AHA! there was "
                                   "a $RECOVERY lock for dead "
                                   "node %u (%s)!\n", 
                                   dead_node, dlm->name);
                              list_del_init(&lock->list);
                              dlm_lock_put(lock);
                              break;
                        }
                  }
                  spin_unlock(&res->spinlock);
                  continue;
            }

            if (res->owner == dead_node) {
                  mlog(0, "found lockres owned by dead node while "
                          "doing recovery for node %u. sending it.\n",
                          dead_node);
                  list_move_tail(&res->recovering, list);
            } else if (res->owner == DLM_LOCK_RES_OWNER_UNKNOWN) {
                  mlog(0, "found UNKNOWN owner while doing recovery "
                          "for node %u. sending it.\n", dead_node);
                  list_move_tail(&res->recovering, list);
            }
      }
      spin_unlock(&dlm->spinlock);
}

static inline int dlm_num_locks_in_lockres(struct dlm_lock_resource *res)
{
      int total_locks = 0;
      struct list_head *iter, *queue = &res->granted;
      int i;

      for (i=0; i<3; i++) {
            list_for_each(iter, queue)
                  total_locks++;
            queue++;
      }
      return total_locks;
}


static int dlm_send_mig_lockres_msg(struct dlm_ctxt *dlm,
                              struct dlm_migratable_lockres *mres,
                              u8 send_to,
                              struct dlm_lock_resource *res,
                              int total_locks)
{
      u64 mig_cookie = be64_to_cpu(mres->mig_cookie);
      int mres_total_locks = be32_to_cpu(mres->total_locks);
      int sz, ret = 0, status = 0;
      u8 orig_flags = mres->flags,
         orig_master = mres->master;

      BUG_ON(mres->num_locks > DLM_MAX_MIGRATABLE_LOCKS);
      if (!mres->num_locks)
            return 0;

      sz = sizeof(struct dlm_migratable_lockres) +
            (mres->num_locks * sizeof(struct dlm_migratable_lock));

      /* add an all-done flag if we reached the last lock */
      orig_flags = mres->flags;
      BUG_ON(total_locks > mres_total_locks);
      if (total_locks == mres_total_locks)
            mres->flags |= DLM_MRES_ALL_DONE;

      mlog(0, "%s:%.*s: sending mig lockres (%s) to %u\n",
           dlm->name, res->lockname.len, res->lockname.name,
           orig_flags & DLM_MRES_MIGRATION ? "migrate" : "recovery",
           send_to);

      /* send it */
      ret = o2net_send_message(DLM_MIG_LOCKRES_MSG, dlm->key, mres,
                         sz, send_to, &status);
      if (ret < 0) {
            /* XXX: negative status is not handled.
             * this will end up killing this node. */
            mlog_errno(ret);
      } else {
            /* might get an -ENOMEM back here */
            ret = status;
            if (ret < 0) {
                  mlog_errno(ret);

                  if (ret == -EFAULT) {
                        mlog(ML_ERROR, "node %u told me to kill "
                             "myself!\n", send_to);
                        BUG();
                  }
            }
      }

      /* zero and reinit the message buffer */
      dlm_init_migratable_lockres(mres, res->lockname.name,
                            res->lockname.len, mres_total_locks,
                            mig_cookie, orig_flags, orig_master);
      return ret;
}

static void dlm_init_migratable_lockres(struct dlm_migratable_lockres *mres,
                              const char *lockname, int namelen,
                              int total_locks, u64 cookie,
                              u8 flags, u8 master)
{
      /* mres here is one full page */
      clear_page(mres);
      mres->lockname_len = namelen;
      memcpy(mres->lockname, lockname, namelen);
      mres->num_locks = 0;
      mres->total_locks = cpu_to_be32(total_locks);
      mres->mig_cookie = cpu_to_be64(cookie);
      mres->flags = flags;
      mres->master = master;
}


/* returns 1 if this lock fills the network structure,
 * 0 otherwise */
static int dlm_add_lock_to_array(struct dlm_lock *lock,
                         struct dlm_migratable_lockres *mres, int queue)
{
      struct dlm_migratable_lock *ml;
      int lock_num = mres->num_locks;

      ml = &(mres->ml[lock_num]);
      ml->cookie = lock->ml.cookie;
      ml->type = lock->ml.type;
      ml->convert_type = lock->ml.convert_type;
      ml->highest_blocked = lock->ml.highest_blocked;
      ml->list = queue;
      if (lock->lksb) {
            ml->flags = lock->lksb->flags;
            /* send our current lvb */
            if (ml->type == LKM_EXMODE ||
                ml->type == LKM_PRMODE) {
                  /* if it is already set, this had better be a PR
                   * and it has to match */
                  if (!dlm_lvb_is_empty(mres->lvb) &&
                      (ml->type == LKM_EXMODE ||
                       memcmp(mres->lvb, lock->lksb->lvb, DLM_LVB_LEN))) {
                        mlog(ML_ERROR, "mismatched lvbs!\n");
                        __dlm_print_one_lock_resource(lock->lockres);
                        BUG();
                  }
                  memcpy(mres->lvb, lock->lksb->lvb, DLM_LVB_LEN);
            }
      }
      ml->node = lock->ml.node;
      mres->num_locks++;
      /* we reached the max, send this network message */
      if (mres->num_locks == DLM_MAX_MIGRATABLE_LOCKS)
            return 1;
      return 0;
}

static void dlm_add_dummy_lock(struct dlm_ctxt *dlm,
                         struct dlm_migratable_lockres *mres)
{
      struct dlm_lock dummy;
      memset(&dummy, 0, sizeof(dummy));
      dummy.ml.cookie = 0;
      dummy.ml.type = LKM_IVMODE;
      dummy.ml.convert_type = LKM_IVMODE;
      dummy.ml.highest_blocked = LKM_IVMODE;
      dummy.lksb = NULL;
      dummy.ml.node = dlm->node_num;
      dlm_add_lock_to_array(&dummy, mres, DLM_BLOCKED_LIST);
}

static inline int dlm_is_dummy_lock(struct dlm_ctxt *dlm,
                            struct dlm_migratable_lock *ml,
                            u8 *nodenum)
{
      if (unlikely(ml->cookie == 0 &&
          ml->type == LKM_IVMODE &&
          ml->convert_type == LKM_IVMODE &&
          ml->highest_blocked == LKM_IVMODE &&
          ml->list == DLM_BLOCKED_LIST)) {
            *nodenum = ml->node;
            return 1;
      }
      return 0;
}

int dlm_send_one_lockres(struct dlm_ctxt *dlm, struct dlm_lock_resource *res,
                   struct dlm_migratable_lockres *mres,
                   u8 send_to, u8 flags)
{
      struct list_head *queue;
      int total_locks, i;
      u64 mig_cookie = 0;
      struct dlm_lock *lock;
      int ret = 0;

      BUG_ON(!(flags & (DLM_MRES_RECOVERY|DLM_MRES_MIGRATION)));

      mlog(0, "sending to %u\n", send_to);

      total_locks = dlm_num_locks_in_lockres(res);
      if (total_locks > DLM_MAX_MIGRATABLE_LOCKS) {
            /* rare, but possible */
            mlog(0, "argh.  lockres has %d locks.  this will "
                    "require more than one network packet to "
                    "migrate\n", total_locks);
            mig_cookie = dlm_get_next_mig_cookie();
      }

      dlm_init_migratable_lockres(mres, res->lockname.name,
                            res->lockname.len, total_locks,
                            mig_cookie, flags, res->owner);

      total_locks = 0;
      for (i=DLM_GRANTED_LIST; i<=DLM_BLOCKED_LIST; i++) {
            queue = dlm_list_idx_to_ptr(res, i);
            list_for_each_entry(lock, queue, list) {
                  /* add another lock. */
                  total_locks++;
                  if (!dlm_add_lock_to_array(lock, mres, i))
                        continue;

                  /* this filled the lock message,
                   * we must send it immediately. */
                  ret = dlm_send_mig_lockres_msg(dlm, mres, send_to,
                                           res, total_locks);
                  if (ret < 0)
                        goto error;
            }
      }
      if (total_locks == 0) {
            /* send a dummy lock to indicate a mastery reference only */
            mlog(0, "%s:%.*s: sending dummy lock to %u, %s\n",
                 dlm->name, res->lockname.len, res->lockname.name,
                 send_to, flags & DLM_MRES_RECOVERY ? "recovery" :
                 "migration");
            dlm_add_dummy_lock(dlm, mres);
      }
      /* flush any remaining locks */
      ret = dlm_send_mig_lockres_msg(dlm, mres, send_to, res, total_locks);
      if (ret < 0)
            goto error;
      return ret;

error:
      mlog(ML_ERROR, "%s: dlm_send_mig_lockres_msg returned %d\n",
           dlm->name, ret);
      if (!dlm_is_host_down(ret))
            BUG();
      mlog(0, "%s: node %u went down while sending %s "
           "lockres %.*s\n", dlm->name, send_to,
           flags & DLM_MRES_RECOVERY ?  "recovery" : "migration",
           res->lockname.len, res->lockname.name);
      return ret;
}



/*
 * this message will contain no more than one page worth of
 * recovery data, and it will work on only one lockres.
 * there may be many locks in this page, and we may need to wait
 * for additional packets to complete all the locks (rare, but
 * possible).
 */
/*
 * NOTE: the allocation error cases here are scary
 * we really cannot afford to fail an alloc in recovery
 * do we spin?  returning an error only delays the problem really
 */

int dlm_mig_lockres_handler(struct o2net_msg *msg, u32 len, void *data,
                      void **ret_data)
{
      struct dlm_ctxt *dlm = data;
      struct dlm_migratable_lockres *mres =
            (struct dlm_migratable_lockres *)msg->buf;
      int ret = 0;
      u8 real_master;
      char *buf = NULL;
      struct dlm_work_item *item = NULL;
      struct dlm_lock_resource *res = NULL;

      if (!dlm_grab(dlm))
            return -EINVAL;

      BUG_ON(!(mres->flags & (DLM_MRES_RECOVERY|DLM_MRES_MIGRATION)));

      real_master = mres->master;
      if (real_master == DLM_LOCK_RES_OWNER_UNKNOWN) {
            /* cannot migrate a lockres with no master */
            BUG_ON(!(mres->flags & DLM_MRES_RECOVERY));
      }

      mlog(0, "%s message received from node %u\n",
              (mres->flags & DLM_MRES_RECOVERY) ?
              "recovery" : "migration", mres->master);
      if (mres->flags & DLM_MRES_ALL_DONE)
            mlog(0, "all done flag.  all lockres data received!\n");

      ret = -ENOMEM;
      buf = kmalloc(be16_to_cpu(msg->data_len), GFP_NOFS);
      item = kzalloc(sizeof(*item), GFP_NOFS);
      if (!buf || !item)
            goto leave;

      /* lookup the lock to see if we have a secondary queue for this
       * already...  just add the locks in and this will have its owner
       * and RECOVERY flag changed when it completes. */
      res = dlm_lookup_lockres(dlm, mres->lockname, mres->lockname_len);
      if (res) {
            /* this will get a ref on res */
            /* mark it as recovering/migrating and hash it */
            spin_lock(&res->spinlock);
            if (mres->flags & DLM_MRES_RECOVERY) {
                  res->state |= DLM_LOCK_RES_RECOVERING;
            } else {
                  if (res->state & DLM_LOCK_RES_MIGRATING) {
                        /* this is at least the second
                         * lockres message */
                        mlog(0, "lock %.*s is already migrating\n",
                                mres->lockname_len,
                                mres->lockname);
                  } else if (res->state & DLM_LOCK_RES_RECOVERING) {
                        /* caller should BUG */
                        mlog(ML_ERROR, "node is attempting to migrate "
                             "lock %.*s, but marked as recovering!\n",
                             mres->lockname_len, mres->lockname);
                        ret = -EFAULT;
                        spin_unlock(&res->spinlock);
                        goto leave;
                  }
                  res->state |= DLM_LOCK_RES_MIGRATING;
            }
            spin_unlock(&res->spinlock);
      } else {
            /* need to allocate, just like if it was
             * mastered here normally  */
            res = dlm_new_lockres(dlm, mres->lockname, mres->lockname_len);
            if (!res)
                  goto leave;

            /* to match the ref that we would have gotten if
             * dlm_lookup_lockres had succeeded */
            dlm_lockres_get(res);

            /* mark it as recovering/migrating and hash it */
            if (mres->flags & DLM_MRES_RECOVERY)
                  res->state |= DLM_LOCK_RES_RECOVERING;
            else
                  res->state |= DLM_LOCK_RES_MIGRATING;

            spin_lock(&dlm->spinlock);
            __dlm_insert_lockres(dlm, res);
            spin_unlock(&dlm->spinlock);

            /* now that the new lockres is inserted,
             * make it usable by other processes */
            spin_lock(&res->spinlock);
            res->state &= ~DLM_LOCK_RES_IN_PROGRESS;
            spin_unlock(&res->spinlock);
            wake_up(&res->wq);

            /* add an extra ref for just-allocated lockres 
             * otherwise the lockres will be purged immediately */
            dlm_lockres_get(res);
      }

      /* at this point we have allocated everything we need,
       * and we have a hashed lockres with an extra ref and
       * the proper res->state flags. */
      ret = 0;
      spin_lock(&res->spinlock);
      /* drop this either when master requery finds a different master
       * or when a lock is added by the recovery worker */
      dlm_lockres_grab_inflight_ref(dlm, res);
      if (mres->master == DLM_LOCK_RES_OWNER_UNKNOWN) {
            /* migration cannot have an unknown master */
            BUG_ON(!(mres->flags & DLM_MRES_RECOVERY));
            mlog(0, "recovery has passed me a lockres with an "
                    "unknown owner.. will need to requery: "
                    "%.*s\n", mres->lockname_len, mres->lockname);
      } else {
            /* take a reference now to pin the lockres, drop it
             * when locks are added in the worker */
            dlm_change_lockres_owner(dlm, res, dlm->node_num);
      }
      spin_unlock(&res->spinlock);

      /* queue up work for dlm_mig_lockres_worker */
      dlm_grab(dlm);  /* get an extra ref for the work item */
      memcpy(buf, msg->buf, be16_to_cpu(msg->data_len));  /* copy the whole message */
      dlm_init_work_item(dlm, item, dlm_mig_lockres_worker, buf);
      item->u.ml.lockres = res; /* already have a ref */
      item->u.ml.real_master = real_master;
      spin_lock(&dlm->work_lock);
      list_add_tail(&item->list, &dlm->work_list);
      spin_unlock(&dlm->work_lock);
      queue_work(dlm->dlm_worker, &dlm->dispatched_work);

leave:
      dlm_put(dlm);
      if (ret < 0) {
            if (buf)
                  kfree(buf);
            if (item)
                  kfree(item);
      }

      mlog_exit(ret);
      return ret;
}


static void dlm_mig_lockres_worker(struct dlm_work_item *item, void *data)
{
      struct dlm_ctxt *dlm = data;
      struct dlm_migratable_lockres *mres;
      int ret = 0;
      struct dlm_lock_resource *res;
      u8 real_master;

      dlm = item->dlm;
      mres = (struct dlm_migratable_lockres *)data;

      res = item->u.ml.lockres;
      real_master = item->u.ml.real_master;

      if (real_master == DLM_LOCK_RES_OWNER_UNKNOWN) {
            /* this case is super-rare. only occurs if
             * node death happens during migration. */
again:
            ret = dlm_lockres_master_requery(dlm, res, &real_master);
            if (ret < 0) {
                  mlog(0, "dlm_lockres_master_requery ret=%d\n",
                          ret);
                  goto again;
            }
            if (real_master == DLM_LOCK_RES_OWNER_UNKNOWN) {
                  mlog(0, "lockres %.*s not claimed.  "
                           "this node will take it.\n",
                           res->lockname.len, res->lockname.name);
            } else {
                  spin_lock(&res->spinlock);
                  dlm_lockres_drop_inflight_ref(dlm, res);
                  spin_unlock(&res->spinlock);
                  mlog(0, "master needs to respond to sender "
                          "that node %u still owns %.*s\n",
                          real_master, res->lockname.len,
                          res->lockname.name);
                  /* cannot touch this lockres */
                  goto leave;
            }
      }

      ret = dlm_process_recovery_data(dlm, res, mres);
      if (ret < 0)
            mlog(0, "dlm_process_recovery_data returned  %d\n", ret);
      else
            mlog(0, "dlm_process_recovery_data succeeded\n");

      if ((mres->flags & (DLM_MRES_MIGRATION|DLM_MRES_ALL_DONE)) ==
                         (DLM_MRES_MIGRATION|DLM_MRES_ALL_DONE)) {
            ret = dlm_finish_migration(dlm, res, mres->master);
            if (ret < 0)
                  mlog_errno(ret);
      }

leave:
      kfree(data);
      mlog_exit(ret);
}



static int dlm_lockres_master_requery(struct dlm_ctxt *dlm,
                              struct dlm_lock_resource *res,
                              u8 *real_master)
{
      struct dlm_node_iter iter;
      int nodenum;
      int ret = 0;

      *real_master = DLM_LOCK_RES_OWNER_UNKNOWN;

      /* we only reach here if one of the two nodes in a
       * migration died while the migration was in progress.
       * at this point we need to requery the master.  we
       * know that the new_master got as far as creating
       * an mle on at least one node, but we do not know
       * if any nodes had actually cleared the mle and set
       * the master to the new_master.  the old master
       * is supposed to set the owner to UNKNOWN in the
       * event of a new_master death, so the only possible
       * responses that we can get from nodes here are
       * that the master is new_master, or that the master
       * is UNKNOWN.
       * if all nodes come back with UNKNOWN then we know
       * the lock needs remastering here.
       * if any node comes back with a valid master, check
       * to see if that master is the one that we are
       * recovering.  if so, then the new_master died and
       * we need to remaster this lock.  if not, then the
       * new_master survived and that node will respond to
       * other nodes about the owner.
       * if there is an owner, this node needs to dump this
       * lockres and alert the sender that this lockres
       * was rejected. */
      spin_lock(&dlm->spinlock);
      dlm_node_iter_init(dlm->domain_map, &iter);
      spin_unlock(&dlm->spinlock);

      while ((nodenum = dlm_node_iter_next(&iter)) >= 0) {
            /* do not send to self */
            if (nodenum == dlm->node_num)
                  continue;
            ret = dlm_do_master_requery(dlm, res, nodenum, real_master);
            if (ret < 0) {
                  mlog_errno(ret);
                  if (!dlm_is_host_down(ret))
                        BUG();
                  /* host is down, so answer for that node would be
                   * DLM_LOCK_RES_OWNER_UNKNOWN.  continue. */
            }
            if (*real_master != DLM_LOCK_RES_OWNER_UNKNOWN) {
                  mlog(0, "lock master is %u\n", *real_master);
                  break;
            }
      }
      return ret;
}


int dlm_do_master_requery(struct dlm_ctxt *dlm, struct dlm_lock_resource *res,
                    u8 nodenum, u8 *real_master)
{
      int ret = -EINVAL;
      struct dlm_master_requery req;
      int status = DLM_LOCK_RES_OWNER_UNKNOWN;

      memset(&req, 0, sizeof(req));
      req.node_idx = dlm->node_num;
      req.namelen = res->lockname.len;
      memcpy(req.name, res->lockname.name, res->lockname.len);

      ret = o2net_send_message(DLM_MASTER_REQUERY_MSG, dlm->key,
                         &req, sizeof(req), nodenum, &status);
      /* XXX: negative status not handled properly here. */
      if (ret < 0)
            mlog_errno(ret);
      else {
            BUG_ON(status < 0);
            BUG_ON(status > DLM_LOCK_RES_OWNER_UNKNOWN);
            *real_master = (u8) (status & 0xff);
            mlog(0, "node %u responded to master requery with %u\n",
                    nodenum, *real_master);
            ret = 0;
      }
      return ret;
}


/* this function cannot error, so unless the sending
 * or receiving of the message failed, the owner can
 * be trusted */
int dlm_master_requery_handler(struct o2net_msg *msg, u32 len, void *data,
                         void **ret_data)
{
      struct dlm_ctxt *dlm = data;
      struct dlm_master_requery *req = (struct dlm_master_requery *)msg->buf;
      struct dlm_lock_resource *res = NULL;
      unsigned int hash;
      int master = DLM_LOCK_RES_OWNER_UNKNOWN;
      u32 flags = DLM_ASSERT_MASTER_REQUERY;

      if (!dlm_grab(dlm)) {
            /* since the domain has gone away on this
             * node, the proper response is UNKNOWN */
            return master;
      }

      hash = dlm_lockid_hash(req->name, req->namelen);

      spin_lock(&dlm->spinlock);
      res = __dlm_lookup_lockres(dlm, req->name, req->namelen, hash);
      if (res) {
            spin_lock(&res->spinlock);
            master = res->owner;
            if (master == dlm->node_num) {
                  int ret = dlm_dispatch_assert_master(dlm, res,
                                               0, 0, flags);
                  if (ret < 0) {
                        mlog_errno(-ENOMEM);
                        /* retry!? */
                        BUG();
                  }
            }
            spin_unlock(&res->spinlock);
      }
      spin_unlock(&dlm->spinlock);

      dlm_put(dlm);
      return master;
}

static inline struct list_head *
dlm_list_num_to_pointer(struct dlm_lock_resource *res, int list_num)
{
      struct list_head *ret;
      BUG_ON(list_num < 0);
      BUG_ON(list_num > 2);
      ret = &(res->granted);
      ret += list_num;
      return ret;
}
/* TODO: do ast flush business
 * TODO: do MIGRATING and RECOVERING spinning
 */

/*
* NOTE about in-flight requests during migration:
*
* Before attempting the migrate, the master has marked the lockres as
* MIGRATING and then flushed all of its pending ASTS.  So any in-flight
* requests either got queued before the MIGRATING flag got set, in which
* case the lock data will reflect the change and a return message is on
* the way, or the request failed to get in before MIGRATING got set.  In
* this case, the caller will be told to spin and wait for the MIGRATING
* flag to be dropped, then recheck the master.
* This holds true for the convert, cancel and unlock cases, and since lvb
* updates are tied to these same messages, it applies to lvb updates as
* well.  For the lock case, there is no way a lock can be on the master
* queue and not be on the secondary queue since the lock is always added
* locally first.  This means that the new target node will never be sent
* a lock that he doesn't already have on the list.
* In total, this means that the local lock is correct and should not be
* updated to match the one sent by the master.  Any messages sent back
* from the master before the MIGRATING flag will bring the lock properly
* up-to-date, and the change will be ordered properly for the waiter.
* We will *not* attempt to modify the lock underneath the waiter.
*/

static int dlm_process_recovery_data(struct dlm_ctxt *dlm,
                             struct dlm_lock_resource *res,
                             struct dlm_migratable_lockres *mres)
{
      struct dlm_migratable_lock *ml;
      struct list_head *queue;
      struct list_head *tmpq = NULL;
      struct dlm_lock *newlock = NULL;
      struct dlm_lockstatus *lksb = NULL;
      int ret = 0;
      int i, j, bad;
      struct dlm_lock *lock = NULL;
      u8 from = O2NM_MAX_NODES;
      unsigned int added = 0;

      mlog(0, "running %d locks for this lockres\n", mres->num_locks);
      for (i=0; i<mres->num_locks; i++) {
            ml = &(mres->ml[i]);

            if (dlm_is_dummy_lock(dlm, ml, &from)) {
                  /* placeholder, just need to set the refmap bit */
                  BUG_ON(mres->num_locks != 1);
                  mlog(0, "%s:%.*s: dummy lock for %u\n",
                       dlm->name, mres->lockname_len, mres->lockname,
                       from);
                  spin_lock(&res->spinlock);
                  dlm_lockres_set_refmap_bit(from, res);
                  spin_unlock(&res->spinlock);
                  added++;
                  break;
            }
            BUG_ON(ml->highest_blocked != LKM_IVMODE);
            newlock = NULL;
            lksb = NULL;

            queue = dlm_list_num_to_pointer(res, ml->list);
            tmpq = NULL;

            /* if the lock is for the local node it needs to
             * be moved to the proper location within the queue.
             * do not allocate a new lock structure. */
            if (ml->node == dlm->node_num) {
                  /* MIGRATION ONLY! */
                  BUG_ON(!(mres->flags & DLM_MRES_MIGRATION));

                  spin_lock(&res->spinlock);
                  for (j = DLM_GRANTED_LIST; j <= DLM_BLOCKED_LIST; j++) {
                        tmpq = dlm_list_idx_to_ptr(res, j);
                        list_for_each_entry(lock, tmpq, list) {
                              if (lock->ml.cookie != ml->cookie)
                                    lock = NULL;
                              else
                                    break;
                        }
                        if (lock)
                              break;
                  }

                  /* lock is always created locally first, and
                   * destroyed locally last.  it must be on the list */
                  if (!lock) {
                        __be64 c = ml->cookie;
                        mlog(ML_ERROR, "could not find local lock "
                                     "with cookie %u:%llu!\n",
                             dlm_get_lock_cookie_node(be64_to_cpu(c)),
                             dlm_get_lock_cookie_seq(be64_to_cpu(c)));
                        __dlm_print_one_lock_resource(res);
                        BUG();
                  }
                  BUG_ON(lock->ml.node != ml->node);

                  if (tmpq != queue) {
                        mlog(0, "lock was on %u instead of %u for %.*s\n",
                             j, ml->list, res->lockname.len, res->lockname.name);
                        spin_unlock(&res->spinlock);
                        continue;
                  }

                  /* see NOTE above about why we do not update
                   * to match the master here */

                  /* move the lock to its proper place */
                  /* do not alter lock refcount.  switching lists. */
                  list_move_tail(&lock->list, queue);
                  spin_unlock(&res->spinlock);
                  added++;

                  mlog(0, "just reordered a local lock!\n");
                  continue;
            }

            /* lock is for another node. */
            newlock = dlm_new_lock(ml->type, ml->node,
                               be64_to_cpu(ml->cookie), NULL);
            if (!newlock) {
                  ret = -ENOMEM;
                  goto leave;
            }
            lksb = newlock->lksb;
            dlm_lock_attach_lockres(newlock, res);

            if (ml->convert_type != LKM_IVMODE) {
                  BUG_ON(queue != &res->converting);
                  newlock->ml.convert_type = ml->convert_type;
            }
            lksb->flags |= (ml->flags &
                        (DLM_LKSB_PUT_LVB|DLM_LKSB_GET_LVB));

            if (ml->type == LKM_NLMODE)
                  goto skip_lvb;

            if (!dlm_lvb_is_empty(mres->lvb)) {
                  if (lksb->flags & DLM_LKSB_PUT_LVB) {
                        /* other node was trying to update
                         * lvb when node died.  recreate the
                         * lksb with the updated lvb. */
                        memcpy(lksb->lvb, mres->lvb, DLM_LVB_LEN);
                        /* the lock resource lvb update must happen
                         * NOW, before the spinlock is dropped.
                         * we no longer wait for the AST to update
                         * the lvb. */
                        memcpy(res->lvb, mres->lvb, DLM_LVB_LEN);
                  } else {
                        /* otherwise, the node is sending its 
                         * most recent valid lvb info */
                        BUG_ON(ml->type != LKM_EXMODE &&
                               ml->type != LKM_PRMODE);
                        if (!dlm_lvb_is_empty(res->lvb) &&
                            (ml->type == LKM_EXMODE ||
                             memcmp(res->lvb, mres->lvb, DLM_LVB_LEN))) {
                              int i;
                              mlog(ML_ERROR, "%s:%.*s: received bad "
                                   "lvb! type=%d\n", dlm->name,
                                   res->lockname.len,
                                   res->lockname.name, ml->type);
                              printk("lockres lvb=[");
                              for (i=0; i<DLM_LVB_LEN; i++)
                                    printk("%02x", res->lvb[i]);
                              printk("]\nmigrated lvb=[");
                              for (i=0; i<DLM_LVB_LEN; i++)
                                    printk("%02x", mres->lvb[i]);
                              printk("]\n");
                              dlm_print_one_lock_resource(res);
                              BUG();
                        }
                        memcpy(res->lvb, mres->lvb, DLM_LVB_LEN);
                  }
            }
skip_lvb:

            /* NOTE:
             * wrt lock queue ordering and recovery:
             *    1. order of locks on granted queue is
             *       meaningless.
             *    2. order of locks on converting queue is
             *       LOST with the node death.  sorry charlie.
             *    3. order of locks on the blocked queue is
             *       also LOST.
             * order of locks does not affect integrity, it
             * just means that a lock request may get pushed
             * back in line as a result of the node death.
             * also note that for a given node the lock order
             * for its secondary queue locks is preserved
             * relative to each other, but clearly *not*
             * preserved relative to locks from other nodes.
             */
            bad = 0;
            spin_lock(&res->spinlock);
            list_for_each_entry(lock, queue, list) {
                  if (lock->ml.cookie == ml->cookie) {
                        __be64 c = lock->ml.cookie;
                        mlog(ML_ERROR, "%s:%.*s: %u:%llu: lock already "
                             "exists on this lockres!\n", dlm->name,
                             res->lockname.len, res->lockname.name,
                             dlm_get_lock_cookie_node(be64_to_cpu(c)),
                             dlm_get_lock_cookie_seq(be64_to_cpu(c)));

                        mlog(ML_NOTICE, "sent lock: type=%d, conv=%d, "
                             "node=%u, cookie=%u:%llu, queue=%d\n",
                                   ml->type, ml->convert_type, ml->node,
                             dlm_get_lock_cookie_node(be64_to_cpu(ml->cookie)),
                             dlm_get_lock_cookie_seq(be64_to_cpu(ml->cookie)),
                             ml->list);

                        __dlm_print_one_lock_resource(res);
                        bad = 1;
                        break;
                  }
            }
            if (!bad) {
                  dlm_lock_get(newlock);
                  list_add_tail(&newlock->list, queue);
                  mlog(0, "%s:%.*s: added lock for node %u, "
                       "setting refmap bit\n", dlm->name,
                       res->lockname.len, res->lockname.name, ml->node);
                  dlm_lockres_set_refmap_bit(ml->node, res);
                  added++;
            }
            spin_unlock(&res->spinlock);
      }
      mlog(0, "done running all the locks\n");

leave:
      /* balance the ref taken when the work was queued */
      spin_lock(&res->spinlock);
      dlm_lockres_drop_inflight_ref(dlm, res);
      spin_unlock(&res->spinlock);

      if (ret < 0) {
            mlog_errno(ret);
            if (newlock)
                  dlm_lock_put(newlock);
      }

      mlog_exit(ret);
      return ret;
}

void dlm_move_lockres_to_recovery_list(struct dlm_ctxt *dlm,
                               struct dlm_lock_resource *res)
{
      int i;
      struct list_head *queue;
      struct dlm_lock *lock, *next;

      res->state |= DLM_LOCK_RES_RECOVERING;
      if (!list_empty(&res->recovering)) {
            mlog(0,
                 "Recovering res %s:%.*s, is already on recovery list!\n",
                 dlm->name, res->lockname.len, res->lockname.name);
            list_del_init(&res->recovering);
      }
      /* We need to hold a reference while on the recovery list */
      dlm_lockres_get(res);
      list_add_tail(&res->recovering, &dlm->reco.resources);

      /* find any pending locks and put them back on proper list */
      for (i=DLM_BLOCKED_LIST; i>=DLM_GRANTED_LIST; i--) {
            queue = dlm_list_idx_to_ptr(res, i);
            list_for_each_entry_safe(lock, next, queue, list) {
                  dlm_lock_get(lock);
                  if (lock->convert_pending) {
                        /* move converting lock back to granted */
                        BUG_ON(i != DLM_CONVERTING_LIST);
                        mlog(0, "node died with convert pending "
                             "on %.*s. move back to granted list.\n",
                             res->lockname.len, res->lockname.name);
                        dlm_revert_pending_convert(res, lock);
                        lock->convert_pending = 0;
                  } else if (lock->lock_pending) {
                        /* remove pending lock requests completely */
                        BUG_ON(i != DLM_BLOCKED_LIST);
                        mlog(0, "node died with lock pending "
                             "on %.*s. remove from blocked list and skip.\n",
                             res->lockname.len, res->lockname.name);
                        /* lock will be floating until ref in
                         * dlmlock_remote is freed after the network
                         * call returns.  ok for it to not be on any
                         * list since no ast can be called
                         * (the master is dead). */
                        dlm_revert_pending_lock(res, lock);
                        lock->lock_pending = 0;
                  } else if (lock->unlock_pending) {
                        /* if an unlock was in progress, treat as
                         * if this had completed successfully
                         * before sending this lock state to the
                         * new master.  note that the dlm_unlock
                         * call is still responsible for calling
                         * the unlockast.  that will happen after
                         * the network call times out.  for now,
                         * just move lists to prepare the new
                         * recovery master.  */
                        BUG_ON(i != DLM_GRANTED_LIST);
                        mlog(0, "node died with unlock pending "
                             "on %.*s. remove from blocked list and skip.\n",
                             res->lockname.len, res->lockname.name);
                        dlm_commit_pending_unlock(res, lock);
                        lock->unlock_pending = 0;
                  } else if (lock->cancel_pending) {
                        /* if a cancel was in progress, treat as
                         * if this had completed successfully
                         * before sending this lock state to the
                         * new master */
                        BUG_ON(i != DLM_CONVERTING_LIST);
                        mlog(0, "node died with cancel pending "
                             "on %.*s. move back to granted list.\n",
                             res->lockname.len, res->lockname.name);
                        dlm_commit_pending_cancel(res, lock);
                        lock->cancel_pending = 0;
                  }
                  dlm_lock_put(lock);
            }
      }
}



/* removes all recovered locks from the recovery list.
 * sets the res->owner to the new master.
 * unsets the RECOVERY flag and wakes waiters. */
static void dlm_finish_local_lockres_recovery(struct dlm_ctxt *dlm,
                                    u8 dead_node, u8 new_master)
{
      int i;
      struct hlist_node *hash_iter;
      struct hlist_head *bucket;
      struct dlm_lock_resource *res, *next;

      mlog_entry_void();

      assert_spin_locked(&dlm->spinlock);

      list_for_each_entry_safe(res, next, &dlm->reco.resources, recovering) {
            if (res->owner == dead_node) {
                  list_del_init(&res->recovering);
                  spin_lock(&res->spinlock);
                  /* new_master has our reference from
                   * the lock state sent during recovery */
                  dlm_change_lockres_owner(dlm, res, new_master);
                  res->state &= ~DLM_LOCK_RES_RECOVERING;
                  if (__dlm_lockres_has_locks(res))
                        __dlm_dirty_lockres(dlm, res);
                  spin_unlock(&res->spinlock);
                  wake_up(&res->wq);
                  dlm_lockres_put(res);
            }
      }

      /* this will become unnecessary eventually, but
       * for now we need to run the whole hash, clear
       * the RECOVERING state and set the owner
       * if necessary */
      for (i = 0; i < DLM_HASH_BUCKETS; i++) {
            bucket = dlm_lockres_hash(dlm, i);
            hlist_for_each_entry(res, hash_iter, bucket, hash_node) {
                  if (res->state & DLM_LOCK_RES_RECOVERING) {
                        if (res->owner == dead_node) {
                              mlog(0, "(this=%u) res %.*s owner=%u "
                                   "was not on recovering list, but "
                                   "clearing state anyway\n",
                                   dlm->node_num, res->lockname.len,
                                   res->lockname.name, new_master);
                        } else if (res->owner == dlm->node_num) {
                              mlog(0, "(this=%u) res %.*s owner=%u "
                                   "was not on recovering list, "
                                   "owner is THIS node, clearing\n",
                                   dlm->node_num, res->lockname.len,
                                   res->lockname.name, new_master);
                        } else
                              continue;

                        if (!list_empty(&res->recovering)) {
                              mlog(0, "%s:%.*s: lockres was "
                                   "marked RECOVERING, owner=%u\n",
                                   dlm->name, res->lockname.len,
                                   res->lockname.name, res->owner);
                              list_del_init(&res->recovering);
                              dlm_lockres_put(res);
                        }
                        spin_lock(&res->spinlock);
                        /* new_master has our reference from
                         * the lock state sent during recovery */
                        dlm_change_lockres_owner(dlm, res, new_master);
                        res->state &= ~DLM_LOCK_RES_RECOVERING;
                        if (__dlm_lockres_has_locks(res))
                              __dlm_dirty_lockres(dlm, res);
                        spin_unlock(&res->spinlock);
                        wake_up(&res->wq);
                  }
            }
      }
}

static inline int dlm_lvb_needs_invalidation(struct dlm_lock *lock, int local)
{
      if (local) {
            if (lock->ml.type != LKM_EXMODE &&
                lock->ml.type != LKM_PRMODE)
                  return 1;
      } else if (lock->ml.type == LKM_EXMODE)
            return 1;
      return 0;
}

static void dlm_revalidate_lvb(struct dlm_ctxt *dlm,
                         struct dlm_lock_resource *res, u8 dead_node)
{
      struct list_head *queue;
      struct dlm_lock *lock;
      int blank_lvb = 0, local = 0;
      int i;
      u8 search_node;

      assert_spin_locked(&dlm->spinlock);
      assert_spin_locked(&res->spinlock);

      if (res->owner == dlm->node_num)
            /* if this node owned the lockres, and if the dead node 
             * had an EX when he died, blank out the lvb */
            search_node = dead_node;
      else {
            /* if this is a secondary lockres, and we had no EX or PR
             * locks granted, we can no longer trust the lvb */
            search_node = dlm->node_num;
            local = 1;  /* check local state for valid lvb */
      }

      for (i=DLM_GRANTED_LIST; i<=DLM_CONVERTING_LIST; i++) {
            queue = dlm_list_idx_to_ptr(res, i);
            list_for_each_entry(lock, queue, list) {
                  if (lock->ml.node == search_node) {
                        if (dlm_lvb_needs_invalidation(lock, local)) {
                              /* zero the lksb lvb and lockres lvb */
                              blank_lvb = 1;
                              memset(lock->lksb->lvb, 0, DLM_LVB_LEN);
                        }
                  }
            }
      }

      if (blank_lvb) {
            mlog(0, "clearing %.*s lvb, dead node %u had EX\n",
                 res->lockname.len, res->lockname.name, dead_node);
            memset(res->lvb, 0, DLM_LVB_LEN);
      }
}

static void dlm_free_dead_locks(struct dlm_ctxt *dlm,
                        struct dlm_lock_resource *res, u8 dead_node)
{
      struct dlm_lock *lock, *next;
      unsigned int freed = 0;

      /* this node is the lockres master:
       * 1) remove any stale locks for the dead node
       * 2) if the dead node had an EX when he died, blank out the lvb 
       */
      assert_spin_locked(&dlm->spinlock);
      assert_spin_locked(&res->spinlock);

      /* TODO: check pending_asts, pending_basts here */
      list_for_each_entry_safe(lock, next, &res->granted, list) {
            if (lock->ml.node == dead_node) {
                  list_del_init(&lock->list);
                  dlm_lock_put(lock);
                  freed++;
            }
      }
      list_for_each_entry_safe(lock, next, &res->converting, list) {
            if (lock->ml.node == dead_node) {
                  list_del_init(&lock->list);
                  dlm_lock_put(lock);
                  freed++;
            }
      }
      list_for_each_entry_safe(lock, next, &res->blocked, list) {
            if (lock->ml.node == dead_node) {
                  list_del_init(&lock->list);
                  dlm_lock_put(lock);
                  freed++;
            }
      }

      if (freed) {
            mlog(0, "%s:%.*s: freed %u locks for dead node %u, "
                 "dropping ref from lockres\n", dlm->name,
                 res->lockname.len, res->lockname.name, freed, dead_node);
            BUG_ON(!test_bit(dead_node, res->refmap));
            dlm_lockres_clear_refmap_bit(dead_node, res);
      } else if (test_bit(dead_node, res->refmap)) {
            mlog(0, "%s:%.*s: dead node %u had a ref, but had "
                 "no locks and had not purged before dying\n", dlm->name,
                 res->lockname.len, res->lockname.name, dead_node);
            dlm_lockres_clear_refmap_bit(dead_node, res);
      }

      /* do not kick thread yet */
      __dlm_dirty_lockres(dlm, res);
}

/* if this node is the recovery master, and there are no
 * locks for a given lockres owned by this node that are in
 * either PR or EX mode, zero out the lvb before requesting.
 *
 */


static void dlm_do_local_recovery_cleanup(struct dlm_ctxt *dlm, u8 dead_node)
{
      struct hlist_node *iter;
      struct dlm_lock_resource *res;
      int i;
      struct hlist_head *bucket;
      struct dlm_lock *lock;


      /* purge any stale mles */
      dlm_clean_master_list(dlm, dead_node);

      /*
       * now clean up all lock resources.  there are two rules:
       *
       * 1) if the dead node was the master, move the lockres
       *    to the recovering list.  set the RECOVERING flag.
       *    this lockres needs to be cleaned up before it can
       *    be used further.
       *
       * 2) if this node was the master, remove all locks from
       *    each of the lockres queues that were owned by the
       *    dead node.  once recovery finishes, the dlm thread
       *    can be kicked again to see if any ASTs or BASTs
       *    need to be fired as a result.
       */
      for (i = 0; i < DLM_HASH_BUCKETS; i++) {
            bucket = dlm_lockres_hash(dlm, i);
            hlist_for_each_entry(res, iter, bucket, hash_node) {
                  /* always prune any $RECOVERY entries for dead nodes,
                   * otherwise hangs can occur during later recovery */
                  if (dlm_is_recovery_lock(res->lockname.name,
                                     res->lockname.len)) {
                        spin_lock(&res->spinlock);
                        list_for_each_entry(lock, &res->granted, list) {
                              if (lock->ml.node == dead_node) {
                                    mlog(0, "AHA! there was "
                                         "a $RECOVERY lock for dead "
                                         "node %u (%s)!\n",
                                         dead_node, dlm->name);
                                    list_del_init(&lock->list);
                                    dlm_lock_put(lock);
                                    break;
                              }
                        }
                        spin_unlock(&res->spinlock);
                        continue;
                  }                 
                  spin_lock(&res->spinlock);
                  /* zero the lvb if necessary */
                  dlm_revalidate_lvb(dlm, res, dead_node);
                  if (res->owner == dead_node) {
                        if (res->state & DLM_LOCK_RES_DROPPING_REF)
                              mlog(0, "%s:%.*s: owned by "
                                   "dead node %u, this node was "
                                   "dropping its ref when it died. "
                                   "continue, dropping the flag.\n",
                                   dlm->name, res->lockname.len,
                                   res->lockname.name, dead_node);

                        /* the wake_up for this will happen when the
                         * RECOVERING flag is dropped later */
                        res->state &= ~DLM_LOCK_RES_DROPPING_REF;

                        dlm_move_lockres_to_recovery_list(dlm, res);
                  } else if (res->owner == dlm->node_num) {
                        dlm_free_dead_locks(dlm, res, dead_node);
                        __dlm_lockres_calc_usage(dlm, res);
                  }
                  spin_unlock(&res->spinlock);
            }
      }

}

static void __dlm_hb_node_down(struct dlm_ctxt *dlm, int idx)
{
      assert_spin_locked(&dlm->spinlock);

      if (dlm->reco.new_master == idx) {
            mlog(0, "%s: recovery master %d just died\n",
                 dlm->name, idx);
            if (dlm->reco.state & DLM_RECO_STATE_FINALIZE) {
                  /* finalize1 was reached, so it is safe to clear
                   * the new_master and dead_node.  that recovery
                   * is complete. */
                  mlog(0, "%s: dead master %d had reached "
                       "finalize1 state, clearing\n", dlm->name, idx);
                  dlm->reco.state &= ~DLM_RECO_STATE_FINALIZE;
                  __dlm_reset_recovery(dlm);
            }
      }

      /* check to see if the node is already considered dead */
      if (!test_bit(idx, dlm->live_nodes_map)) {
            mlog(0, "for domain %s, node %d is already dead. "
                 "another node likely did recovery already.\n",
                 dlm->name, idx);
            return;
      }

      /* check to see if we do not care about this node */
      if (!test_bit(idx, dlm->domain_map)) {
            /* This also catches the case that we get a node down
             * but haven't joined the domain yet. */
            mlog(0, "node %u already removed from domain!\n", idx);
            return;
      }

      clear_bit(idx, dlm->live_nodes_map);

      /* Clean up join state on node death. */
      if (dlm->joining_node == idx) {
            mlog(0, "Clearing join state for node %u\n", idx);
            __dlm_set_joining_node(dlm, DLM_LOCK_RES_OWNER_UNKNOWN);
      }

      /* make sure local cleanup occurs before the heartbeat events */
      if (!test_bit(idx, dlm->recovery_map))
            dlm_do_local_recovery_cleanup(dlm, idx);

      /* notify anything attached to the heartbeat events */
      dlm_hb_event_notify_attached(dlm, idx, 0);

      mlog(0, "node %u being removed from domain map!\n", idx);
      clear_bit(idx, dlm->domain_map);
      /* wake up migration waiters if a node goes down.
       * perhaps later we can genericize this for other waiters. */
      wake_up(&dlm->migration_wq);

      if (test_bit(idx, dlm->recovery_map))
            mlog(0, "domain %s, node %u already added "
                 "to recovery map!\n", dlm->name, idx);
      else
            set_bit(idx, dlm->recovery_map);
}

void dlm_hb_node_down_cb(struct o2nm_node *node, int idx, void *data)
{
      struct dlm_ctxt *dlm = data;

      if (!dlm_grab(dlm))
            return;

      spin_lock(&dlm->spinlock);
      __dlm_hb_node_down(dlm, idx);
      spin_unlock(&dlm->spinlock);

      dlm_put(dlm);
}

void dlm_hb_node_up_cb(struct o2nm_node *node, int idx, void *data)
{
      struct dlm_ctxt *dlm = data;

      if (!dlm_grab(dlm))
            return;

      spin_lock(&dlm->spinlock);
      set_bit(idx, dlm->live_nodes_map);
      /* do NOT notify mle attached to the heartbeat events.
       * new nodes are not interesting in mastery until joined. */
      spin_unlock(&dlm->spinlock);

      dlm_put(dlm);
}

static void dlm_reco_ast(void *astdata)
{
      struct dlm_ctxt *dlm = astdata;
      mlog(0, "ast for recovery lock fired!, this=%u, dlm=%s\n",
           dlm->node_num, dlm->name);
}
static void dlm_reco_bast(void *astdata, int blocked_type)
{
      struct dlm_ctxt *dlm = astdata;
      mlog(0, "bast for recovery lock fired!, this=%u, dlm=%s\n",
           dlm->node_num, dlm->name);
}
static void dlm_reco_unlock_ast(void *astdata, enum dlm_status st)
{
      mlog(0, "unlockast for recovery lock fired!\n");
}

/*
 * dlm_pick_recovery_master will continually attempt to use
 * dlmlock() on the special "$RECOVERY" lockres with the
 * LKM_NOQUEUE flag to get an EX.  every thread that enters
 * this function on each node racing to become the recovery
 * master will not stop attempting this until either:
 * a) this node gets the EX (and becomes the recovery master),
 * or b) dlm->reco.new_master gets set to some nodenum 
 * != O2NM_INVALID_NODE_NUM (another node will do the reco).
 * so each time a recovery master is needed, the entire cluster
 * will sync at this point.  if the new master dies, that will
 * be detected in dlm_do_recovery */
static int dlm_pick_recovery_master(struct dlm_ctxt *dlm)
{
      enum dlm_status ret;
      struct dlm_lockstatus lksb;
      int status = -EINVAL;

      mlog(0, "starting recovery of %s at %lu, dead=%u, this=%u\n",
           dlm->name, jiffies, dlm->reco.dead_node, dlm->node_num);
again:      
      memset(&lksb, 0, sizeof(lksb));

      ret = dlmlock(dlm, LKM_EXMODE, &lksb, LKM_NOQUEUE|LKM_RECOVERY,
                  DLM_RECOVERY_LOCK_NAME, DLM_RECOVERY_LOCK_NAME_LEN,
                  dlm_reco_ast, dlm, dlm_reco_bast);

      mlog(0, "%s: dlmlock($RECOVERY) returned %d, lksb=%d\n",
           dlm->name, ret, lksb.status);

      if (ret == DLM_NORMAL) {
            mlog(0, "dlm=%s dlmlock says I got it (this=%u)\n",
                 dlm->name, dlm->node_num);
            
            /* got the EX lock.  check to see if another node 
             * just became the reco master */
            if (dlm_reco_master_ready(dlm)) {
                  mlog(0, "%s: got reco EX lock, but %u will "
                       "do the recovery\n", dlm->name,
                       dlm->reco.new_master);
                  status = -EEXIST;
            } else {
                  status = 0;

                  /* see if recovery was already finished elsewhere */
                  spin_lock(&dlm->spinlock);
                  if (dlm->reco.dead_node == O2NM_INVALID_NODE_NUM) {
                        status = -EINVAL; 
                        mlog(0, "%s: got reco EX lock, but "
                             "node got recovered already\n", dlm->name);
                        if (dlm->reco.new_master != O2NM_INVALID_NODE_NUM) {
                              mlog(ML_ERROR, "%s: new master is %u "
                                   "but no dead node!\n", 
                                   dlm->name, dlm->reco.new_master);
                              BUG();
                        }
                  }
                  spin_unlock(&dlm->spinlock);
            }

            /* if this node has actually become the recovery master,
             * set the master and send the messages to begin recovery */
            if (!status) {
                  mlog(0, "%s: dead=%u, this=%u, sending "
                       "begin_reco now\n", dlm->name, 
                       dlm->reco.dead_node, dlm->node_num);
                  status = dlm_send_begin_reco_message(dlm,
                              dlm->reco.dead_node);
                  /* this always succeeds */
                  BUG_ON(status);

                  /* set the new_master to this node */
                  spin_lock(&dlm->spinlock);
                  dlm_set_reco_master(dlm, dlm->node_num);
                  spin_unlock(&dlm->spinlock);
            }

            /* recovery lock is a special case.  ast will not get fired,
             * so just go ahead and unlock it. */
            ret = dlmunlock(dlm, &lksb, 0, dlm_reco_unlock_ast, dlm);
            if (ret == DLM_DENIED) {
                  mlog(0, "got DLM_DENIED, trying LKM_CANCEL\n");
                  ret = dlmunlock(dlm, &lksb, LKM_CANCEL, dlm_reco_unlock_ast, dlm);
            }
            if (ret != DLM_NORMAL) {
                  /* this would really suck. this could only happen
                   * if there was a network error during the unlock
                   * because of node death.  this means the unlock
                   * is actually "done" and the lock structure is
                   * even freed.  we can continue, but only
                   * because this specific lock name is special. */
                  mlog(ML_ERROR, "dlmunlock returned %d\n", ret);
            }
      } else if (ret == DLM_NOTQUEUED) {
            mlog(0, "dlm=%s dlmlock says another node got it (this=%u)\n",
                 dlm->name, dlm->node_num);
            /* another node is master. wait on
             * reco.new_master != O2NM_INVALID_NODE_NUM 
             * for at most one second */
            wait_event_timeout(dlm->dlm_reco_thread_wq,
                               dlm_reco_master_ready(dlm),
                               msecs_to_jiffies(1000));
            if (!dlm_reco_master_ready(dlm)) {
                  mlog(0, "%s: reco master taking awhile\n",
                       dlm->name);
                  goto again;
            }
            /* another node has informed this one that it is reco master */
            mlog(0, "%s: reco master %u is ready to recover %u\n",
                 dlm->name, dlm->reco.new_master, dlm->reco.dead_node);
            status = -EEXIST;
      } else if (ret == DLM_RECOVERING) {
            mlog(0, "dlm=%s dlmlock says master node died (this=%u)\n",
                 dlm->name, dlm->node_num);
            goto again;
      } else {
            struct dlm_lock_resource *res;

            /* dlmlock returned something other than NOTQUEUED or NORMAL */
            mlog(ML_ERROR, "%s: got %s from dlmlock($RECOVERY), "
                 "lksb.status=%s\n", dlm->name, dlm_errname(ret),
                 dlm_errname(lksb.status));
            res = dlm_lookup_lockres(dlm, DLM_RECOVERY_LOCK_NAME,
                               DLM_RECOVERY_LOCK_NAME_LEN);
            if (res) {
                  dlm_print_one_lock_resource(res);
                  dlm_lockres_put(res);
            } else {
                  mlog(ML_ERROR, "recovery lock not found\n");
            }
            BUG();
      }

      return status;
}

static int dlm_send_begin_reco_message(struct dlm_ctxt *dlm, u8 dead_node)
{
      struct dlm_begin_reco br;
      int ret = 0;
      struct dlm_node_iter iter;
      int nodenum;
      int status;

      mlog_entry("%u\n", dead_node);

      mlog(0, "%s: dead node is %u\n", dlm->name, dead_node);

      spin_lock(&dlm->spinlock);
      dlm_node_iter_init(dlm->domain_map, &iter);
      spin_unlock(&dlm->spinlock);

      clear_bit(dead_node, iter.node_map);

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

      while ((nodenum = dlm_node_iter_next(&iter)) >= 0) {
            ret = 0;
            if (nodenum == dead_node) {
                  mlog(0, "not sending begin reco to dead node "
                          "%u\n", dead_node);
                  continue;
            }
            if (nodenum == dlm->node_num) {
                  mlog(0, "not sending begin reco to self\n");
                  continue;
            }
retry:
            ret = -EINVAL;
            mlog(0, "attempting to send begin reco msg to %d\n",
                    nodenum);
            ret = o2net_send_message(DLM_BEGIN_RECO_MSG, dlm->key,
                               &br, sizeof(br), nodenum, &status);
            /* negative status is handled ok by caller here */
            if (ret >= 0)
                  ret = status;
            if (dlm_is_host_down(ret)) {
                  /* node is down.  not involved in recovery
                   * so just keep going */
                  mlog(0, "%s: node %u was down when sending "
                       "begin reco msg (%d)\n", dlm->name, nodenum, ret);
                  ret = 0;
            }
            if (ret < 0) {
                  struct dlm_lock_resource *res;
                  /* this is now a serious problem, possibly ENOMEM 
                   * in the network stack.  must retry */
                  mlog_errno(ret);
                  mlog(ML_ERROR, "begin reco of dlm %s to node %u "
                      " returned %d\n", dlm->name, nodenum, ret);
                  res = dlm_lookup_lockres(dlm, DLM_RECOVERY_LOCK_NAME,
                                     DLM_RECOVERY_LOCK_NAME_LEN);
                  if (res) {
                        dlm_print_one_lock_resource(res);
                        dlm_lockres_put(res);
                  } else {
                        mlog(ML_ERROR, "recovery lock not found\n");
                  }
                  /* sleep for a bit in hopes that we can avoid 
                   * another ENOMEM */
                  msleep(100);
                  goto retry;
            } else if (ret == EAGAIN) {
                  mlog(0, "%s: trying to start recovery of node "
                       "%u, but node %u is waiting for last recovery "
                       "to complete, backoff for a bit\n", dlm->name,
                       dead_node, nodenum);
                  /* TODO Look into replacing msleep with cond_resched() */
                  msleep(100);
                  goto retry;
            }
      }

      return ret;
}

int dlm_begin_reco_handler(struct o2net_msg *msg, u32 len, void *data,
                     void **ret_data)
{
      struct dlm_ctxt *dlm = data;
      struct dlm_begin_reco *br = (struct dlm_begin_reco *)msg->buf;

      /* ok to return 0, domain has gone away */
      if (!dlm_grab(dlm))
            return 0;

      spin_lock(&dlm->spinlock);
      if (dlm->reco.state & DLM_RECO_STATE_FINALIZE) {
            mlog(0, "%s: node %u wants to recover node %u (%u:%u) "
                 "but this node is in finalize state, waiting on finalize2\n",
                 dlm->name, br->node_idx, br->dead_node,
                 dlm->reco.dead_node, dlm->reco.new_master);
            spin_unlock(&dlm->spinlock);
            return EAGAIN;
      }
      spin_unlock(&dlm->spinlock);

      mlog(0, "%s: node %u wants to recover node %u (%u:%u)\n",
           dlm->name, br->node_idx, br->dead_node,
           dlm->reco.dead_node, dlm->reco.new_master);

      dlm_fire_domain_eviction_callbacks(dlm, br->dead_node);

      spin_lock(&dlm->spinlock);
      if (dlm->reco.new_master != O2NM_INVALID_NODE_NUM) {
            if (test_bit(dlm->reco.new_master, dlm->recovery_map)) {
                  mlog(0, "%s: new_master %u died, changing "
                       "to %u\n", dlm->name, dlm->reco.new_master,
                       br->node_idx);
            } else {
                  mlog(0, "%s: new_master %u NOT DEAD, changing "
                       "to %u\n", dlm->name, dlm->reco.new_master,
                       br->node_idx);
                  /* may not have seen the new master as dead yet */
            }
      }
      if (dlm->reco.dead_node != O2NM_INVALID_NODE_NUM) {
            mlog(ML_NOTICE, "%s: dead_node previously set to %u, "
                 "node %u changing it to %u\n", dlm->name, 
                 dlm->reco.dead_node, br->node_idx, br->dead_node);
      }
      dlm_set_reco_master(dlm, br->node_idx);
      dlm_set_reco_dead_node(dlm, br->dead_node);
      if (!test_bit(br->dead_node, dlm->recovery_map)) {
            mlog(0, "recovery master %u sees %u as dead, but this "
                 "node has not yet.  marking %u as dead\n",
                 br->node_idx, br->dead_node, br->dead_node);
            if (!test_bit(br->dead_node, dlm->domain_map) ||
                !test_bit(br->dead_node, dlm->live_nodes_map))
                  mlog(0, "%u not in domain/live_nodes map "
                       "so setting it in reco map manually\n",
                       br->dead_node);
            /* force the recovery cleanup in __dlm_hb_node_down
             * both of these will be cleared in a moment */
            set_bit(br->dead_node, dlm->domain_map);
            set_bit(br->dead_node, dlm->live_nodes_map);
            __dlm_hb_node_down(dlm, br->dead_node);
      }
      spin_unlock(&dlm->spinlock);

      dlm_kick_recovery_thread(dlm);

      mlog(0, "%s: recovery started by node %u, for %u (%u:%u)\n",
           dlm->name, br->node_idx, br->dead_node,
           dlm->reco.dead_node, dlm->reco.new_master);

      dlm_put(dlm);
      return 0;
}

#define DLM_FINALIZE_STAGE2  0x01
static int dlm_send_finalize_reco_message(struct dlm_ctxt *dlm)
{
      int ret = 0;
      struct dlm_finalize_reco fr;
      struct dlm_node_iter iter;
      int nodenum;
      int status;
      int stage = 1;

      mlog(0, "finishing recovery for node %s:%u, "
           "stage %d\n", dlm->name, dlm->reco.dead_node, stage);

      spin_lock(&dlm->spinlock);
      dlm_node_iter_init(dlm->domain_map, &iter);
      spin_unlock(&dlm->spinlock);

stage2:
      memset(&fr, 0, sizeof(fr));
      fr.node_idx = dlm->node_num;
      fr.dead_node = dlm->reco.dead_node;
      if (stage == 2)
            fr.flags |= DLM_FINALIZE_STAGE2;

      while ((nodenum = dlm_node_iter_next(&iter)) >= 0) {
            if (nodenum == dlm->node_num)
                  continue;
            ret = o2net_send_message(DLM_FINALIZE_RECO_MSG, dlm->key,
                               &fr, sizeof(fr), nodenum, &status);
            if (ret >= 0)
                  ret = status;
            if (ret < 0) {
                  mlog_errno(ret);
                  if (dlm_is_host_down(ret)) {
                        /* this has no effect on this recovery 
                         * session, so set the status to zero to 
                         * finish out the last recovery */
                        mlog(ML_ERROR, "node %u went down after this "
                             "node finished recovery.\n", nodenum);
                        ret = 0;
                        continue;
                  }
                  break;
            }
      }
      if (stage == 1) {
            /* reset the node_iter back to the top and send finalize2 */
            iter.curnode = -1;
            stage = 2;
            goto stage2;
      }

      return ret;
}

int dlm_finalize_reco_handler(struct o2net_msg *msg, u32 len, void *data,
                        void **ret_data)
{
      struct dlm_ctxt *dlm = data;
      struct dlm_finalize_reco *fr = (struct dlm_finalize_reco *)msg->buf;
      int stage = 1;

      /* ok to return 0, domain has gone away */
      if (!dlm_grab(dlm))
            return 0;

      if (fr->flags & DLM_FINALIZE_STAGE2)
            stage = 2;

      mlog(0, "%s: node %u finalizing recovery stage%d of "
           "node %u (%u:%u)\n", dlm->name, fr->node_idx, stage,
           fr->dead_node, dlm->reco.dead_node, dlm->reco.new_master);
 
      spin_lock(&dlm->spinlock);

      if (dlm->reco.new_master != fr->node_idx) {
            mlog(ML_ERROR, "node %u sent recovery finalize msg, but node "
                 "%u is supposed to be the new master, dead=%u\n",
                 fr->node_idx, dlm->reco.new_master, fr->dead_node);
            BUG();
      }
      if (dlm->reco.dead_node != fr->dead_node) {
            mlog(ML_ERROR, "node %u sent recovery finalize msg for dead "
                 "node %u, but node %u is supposed to be dead\n",
                 fr->node_idx, fr->dead_node, dlm->reco.dead_node);
            BUG();
      }

      switch (stage) {
            case 1:
                  dlm_finish_local_lockres_recovery(dlm, fr->dead_node, fr->node_idx);
                  if (dlm->reco.state & DLM_RECO_STATE_FINALIZE) {
                        mlog(ML_ERROR, "%s: received finalize1 from "
                             "new master %u for dead node %u, but "
                             "this node has already received it!\n",
                             dlm->name, fr->node_idx, fr->dead_node);
                        dlm_print_reco_node_status(dlm);
                        BUG();
                  }
                  dlm->reco.state |= DLM_RECO_STATE_FINALIZE;
                  spin_unlock(&dlm->spinlock);
                  break;
            case 2:
                  if (!(dlm->reco.state & DLM_RECO_STATE_FINALIZE)) {
                        mlog(ML_ERROR, "%s: received finalize2 from "
                             "new master %u for dead node %u, but "
                             "this node did not have finalize1!\n",
                             dlm->name, fr->node_idx, fr->dead_node);
                        dlm_print_reco_node_status(dlm);
                        BUG();
                  }
                  dlm->reco.state &= ~DLM_RECO_STATE_FINALIZE;
                  spin_unlock(&dlm->spinlock);
                  dlm_reset_recovery(dlm);
                  dlm_kick_recovery_thread(dlm);
                  break;
            default:
                  BUG();
      }

      mlog(0, "%s: recovery done, reco master was %u, dead now %u, master now %u\n",
           dlm->name, fr->node_idx, dlm->reco.dead_node, dlm->reco.new_master);

      dlm_put(dlm);
      return 0;
}

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