ClabureDB: Classified Bug-Reports Database

   /* -*- mode: c; c-basic-offset: 8; -*-
    * vim: noexpandtab sw=8 ts=8 sts=0:
    *
    * dlmdomain.c
    *
    * defines domain join / leave apis
    *
    * Copyright (C) 2004 Oracle.  All rights reserved.
    *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public
   * License as published by the Free Software Foundation; either
   * version 2 of the License, or (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * General Public License for more details.
   *
   * You should have received a copy of the GNU General Public
   * License along with this program; if not, write to the
   * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   * Boston, MA 021110-1307, USA.
   *
   */
  
  #include <linux/module.h>
  #include <linux/types.h>
  #include <linux/slab.h>
  #include <linux/highmem.h>
  #include <linux/utsname.h>
  #include <linux/init.h>
  #include <linux/spinlock.h>
  #include <linux/delay.h>
  #include <linux/err.h>
  #include <linux/debugfs.h>
  
  #include "cluster/heartbeat.h"
  #include "cluster/nodemanager.h"
  #include "cluster/tcp.h"
  
  #include "dlmapi.h"
  #include "dlmcommon.h"
  #include "dlmdomain.h"
  #include "dlmdebug.h"
  
  #include "dlmver.h"
  
  #define MLOG_MASK_PREFIX (ML_DLM|ML_DLM_DOMAIN)
  #include "cluster/masklog.h"
  
  /*
   * ocfs2 node maps are array of long int, which limits to send them freely
   * across the wire due to endianness issues. To workaround this, we convert
   * long ints to byte arrays. Following 3 routines are helper functions to
   * set/test/copy bits within those array of bytes
   */
  static inline void byte_set_bit(u8 nr, u8 map[])
  {
          map[nr >> 3] |= (1UL << (nr & 7));
  }
  
  static inline int byte_test_bit(u8 nr, u8 map[])
  {
          return ((1UL << (nr & 7)) & (map[nr >> 3])) != 0;
  }
  
  static inline void byte_copymap(u8 dmap[], unsigned long smap[],
                          unsigned int sz)
  {
          unsigned int nn;
  
          if (!sz)
                  return;
  
          memset(dmap, 0, ((sz + 7) >> 3));
          for (nn = 0 ; nn < sz; nn++)
                  if (test_bit(nn, smap))
                          byte_set_bit(nn, dmap);
  }
  
  static void dlm_free_pagevec(void **vec, int pages)
  {
          while (pages--)
                  free_page((unsigned long)vec[pages]);
          kfree(vec);
  }
  
  static void **dlm_alloc_pagevec(int pages)
  {
          void **vec = kmalloc(pages * sizeof(void *), GFP_KERNEL);
          int i;
  
          if (!vec)
                  return NULL;
  
          for (i = 0; i < pages; i++)
                  if (!(vec[i] = (void *)__get_free_page(GFP_KERNEL)))
                          goto out_free;
 
         mlog(0, "Allocated DLM hash pagevec; %d pages (%lu expected), %lu buckets per page\n",
              pages, (unsigned long)DLM_HASH_PAGES,
              (unsigned long)DLM_BUCKETS_PER_PAGE);
         return vec;
 out_free:
         dlm_free_pagevec(vec, i);
         return NULL;
 }
 
 /*
  *
  * spinlock lock ordering: if multiple locks are needed, obey this ordering:
  *    dlm_domain_lock
  *    struct dlm_ctxt->spinlock
  *    struct dlm_lock_resource->spinlock
  *    struct dlm_ctxt->master_lock
  *    struct dlm_ctxt->ast_lock
  *    dlm_master_list_entry->spinlock
  *    dlm_lock->spinlock
  *
  */
 
 DEFINE_SPINLOCK(dlm_domain_lock);
 LIST_HEAD(dlm_domains);
 static DECLARE_WAIT_QUEUE_HEAD(dlm_domain_events);
 
 /*
  * The supported protocol version for DLM communication.  Running domains
  * will have a negotiated version with the same major number and a minor
  * number equal or smaller.  The dlm_ctxt->dlm_locking_proto field should
  * be used to determine what a running domain is actually using.
  */
 static const struct dlm_protocol_version dlm_protocol = {
         .pv_major = 1,
         .pv_minor = 0,
 };
 
 #define DLM_DOMAIN_BACKOFF_MS 200
 
 static int dlm_query_join_handler(struct o2net_msg *msg, u32 len, void *data,
                                   void **ret_data);
 static int dlm_assert_joined_handler(struct o2net_msg *msg, u32 len, void *data,
                                      void **ret_data);
 static int dlm_cancel_join_handler(struct o2net_msg *msg, u32 len, void *data,
                                    void **ret_data);
 static int dlm_exit_domain_handler(struct o2net_msg *msg, u32 len, void *data,
                                    void **ret_data);
 static int dlm_protocol_compare(struct dlm_protocol_version *existing,
                                 struct dlm_protocol_version *request);
 
 static void dlm_unregister_domain_handlers(struct dlm_ctxt *dlm);
 
 void __dlm_unhash_lockres(struct dlm_lock_resource *lockres)
 {
         if (!hlist_unhashed(&lockres->hash_node)) {
                 hlist_del_init(&lockres->hash_node);
                 dlm_lockres_put(lockres);
         }
 }
 
 void __dlm_insert_lockres(struct dlm_ctxt *dlm,
                        struct dlm_lock_resource *res)
 {
         struct hlist_head *bucket;
         struct qstr *q;
 
         assert_spin_locked(&dlm->spinlock);
 
         q = &res->lockname;
         bucket = dlm_lockres_hash(dlm, q->hash);
 
         /* get a reference for our hashtable */
         dlm_lockres_get(res);
 
         hlist_add_head(&res->hash_node, bucket);
 }
 
 struct dlm_lock_resource * __dlm_lookup_lockres_full(struct dlm_ctxt *dlm,
                                                      const char *name,
                                                      unsigned int len,
                                                      unsigned int hash)
 {
         struct hlist_head *bucket;
         struct hlist_node *list;
 
         mlog_entry("%.*s\n", len, name);
 
         assert_spin_locked(&dlm->spinlock);
 
         bucket = dlm_lockres_hash(dlm, hash);
 
         hlist_for_each(list, bucket) {
                 struct dlm_lock_resource *res = hlist_entry(list,
                         struct dlm_lock_resource, hash_node);
                 if (res->lockname.name[0] != name[0])
                         continue;
                 if (unlikely(res->lockname.len != len))
                         continue;
                 if (memcmp(res->lockname.name + 1, name + 1, len - 1))
                         continue;
                 dlm_lockres_get(res);
                 return res;
         }
         return NULL;
 }
 
 /* intended to be called by functions which do not care about lock
  * resources which are being purged (most net _handler functions).
  * this will return NULL for any lock resource which is found but
  * currently in the process of dropping its mastery reference.
  * use __dlm_lookup_lockres_full when you need the lock resource
  * regardless (e.g. dlm_get_lock_resource) */
 struct dlm_lock_resource * __dlm_lookup_lockres(struct dlm_ctxt *dlm,
                                                 const char *name,
                                                 unsigned int len,
                                                 unsigned int hash)
 {
         struct dlm_lock_resource *res = NULL;
 
         mlog_entry("%.*s\n", len, name);
 
         assert_spin_locked(&dlm->spinlock);
 
         res = __dlm_lookup_lockres_full(dlm, name, len, hash);
         if (res) {
                 spin_lock(&res->spinlock);
                 if (res->state & DLM_LOCK_RES_DROPPING_REF) {
                         spin_unlock(&res->spinlock);
                         dlm_lockres_put(res);
                         return NULL;
                 }
                 spin_unlock(&res->spinlock);
         }
 
         return res;
 }
 
 struct dlm_lock_resource * dlm_lookup_lockres(struct dlm_ctxt *dlm,
                                     const char *name,
                                     unsigned int len)
 {
         struct dlm_lock_resource *res;
         unsigned int hash = dlm_lockid_hash(name, len);
 
         spin_lock(&dlm->spinlock);
         res = __dlm_lookup_lockres(dlm, name, len, hash);
         spin_unlock(&dlm->spinlock);
         return res;
 }
 
 static struct dlm_ctxt * __dlm_lookup_domain_full(const char *domain, int len)
 {
         struct dlm_ctxt *tmp = NULL;
         struct list_head *iter;
 
         assert_spin_locked(&dlm_domain_lock);
 
         /* tmp->name here is always NULL terminated,
          * but domain may not be! */
         list_for_each(iter, &dlm_domains) {
                 tmp = list_entry (iter, struct dlm_ctxt, list);
                 if (strlen(tmp->name) == len &&
                     memcmp(tmp->name, domain, len)==0)
                         break;
                 tmp = NULL;
         }
 
         return tmp;
 }
 
 /* For null terminated domain strings ONLY */
 static struct dlm_ctxt * __dlm_lookup_domain(const char *domain)
 {
         assert_spin_locked(&dlm_domain_lock);
 
         return __dlm_lookup_domain_full(domain, strlen(domain));
 }
 
 
 /* returns true on one of two conditions:
  * 1) the domain does not exist
  * 2) the domain exists and it's state is "joined" */
 static int dlm_wait_on_domain_helper(const char *domain)
 {
         int ret = 0;
         struct dlm_ctxt *tmp = NULL;
 
         spin_lock(&dlm_domain_lock);
 
         tmp = __dlm_lookup_domain(domain);
         if (!tmp)
                 ret = 1;
         else if (tmp->dlm_state == DLM_CTXT_JOINED)
                 ret = 1;
 
         spin_unlock(&dlm_domain_lock);
         return ret;
 }
 
 static void dlm_free_ctxt_mem(struct dlm_ctxt *dlm)
 {
         dlm_destroy_debugfs_subroot(dlm);
 
         if (dlm->lockres_hash)
                 dlm_free_pagevec((void **)dlm->lockres_hash, DLM_HASH_PAGES);
 
         if (dlm->name)
                 kfree(dlm->name);
 
         kfree(dlm);
 }
 
 /* A little strange - this function will be called while holding
  * dlm_domain_lock and is expected to be holding it on the way out. We
  * will however drop and reacquire it multiple times */
 static void dlm_ctxt_release(struct kref *kref)
 {
         struct dlm_ctxt *dlm;
 
         dlm = container_of(kref, struct dlm_ctxt, dlm_refs);
 
         BUG_ON(dlm->num_joins);
         BUG_ON(dlm->dlm_state == DLM_CTXT_JOINED);
 
         /* we may still be in the list if we hit an error during join. */
         list_del_init(&dlm->list);
 
         spin_unlock(&dlm_domain_lock);
 
         mlog(0, "freeing memory from domain %s\n", dlm->name);
 
         wake_up(&dlm_domain_events);
 
         dlm_free_ctxt_mem(dlm);
 
         spin_lock(&dlm_domain_lock);
 }
 
 void dlm_put(struct dlm_ctxt *dlm)
 {
         spin_lock(&dlm_domain_lock);
         kref_put(&dlm->dlm_refs, dlm_ctxt_release);
         spin_unlock(&dlm_domain_lock);
 }
 
 static void __dlm_get(struct dlm_ctxt *dlm)
 {
         kref_get(&dlm->dlm_refs);
 }
 
 /* given a questionable reference to a dlm object, gets a reference if
  * it can find it in the list, otherwise returns NULL in which case
  * you shouldn't trust your pointer. */
 struct dlm_ctxt *dlm_grab(struct dlm_ctxt *dlm)
 {
         struct list_head *iter;
         struct dlm_ctxt *target = NULL;
 
         spin_lock(&dlm_domain_lock);
 
         list_for_each(iter, &dlm_domains) {
                 target = list_entry (iter, struct dlm_ctxt, list);
 
                 if (target == dlm) {
                         __dlm_get(target);
                         break;
                 }
 
                 target = NULL;
         }
 
         spin_unlock(&dlm_domain_lock);
 
         return target;
 }
 
 int dlm_domain_fully_joined(struct dlm_ctxt *dlm)
 {
         int ret;
 
         spin_lock(&dlm_domain_lock);
         ret = (dlm->dlm_state == DLM_CTXT_JOINED) ||
                 (dlm->dlm_state == DLM_CTXT_IN_SHUTDOWN);
         spin_unlock(&dlm_domain_lock);
 
         return ret;
 }
 
 static void dlm_destroy_dlm_worker(struct dlm_ctxt *dlm)
 {
         if (dlm->dlm_worker) {
                 flush_workqueue(dlm->dlm_worker);
                 destroy_workqueue(dlm->dlm_worker);
                 dlm->dlm_worker = NULL;
         }
 }
 
 static void dlm_complete_dlm_shutdown(struct dlm_ctxt *dlm)
 {
         dlm_unregister_domain_handlers(dlm);
         dlm_debug_shutdown(dlm);
         dlm_complete_thread(dlm);
         dlm_complete_recovery_thread(dlm);
         dlm_destroy_dlm_worker(dlm);
 
         /* We've left the domain. Now we can take ourselves out of the
          * list and allow the kref stuff to help us free the
          * memory. */
         spin_lock(&dlm_domain_lock);
         list_del_init(&dlm->list);
         spin_unlock(&dlm_domain_lock);
 
         /* Wake up anyone waiting for us to remove this domain */
         wake_up(&dlm_domain_events);
 }
 
 static int dlm_migrate_all_locks(struct dlm_ctxt *dlm)
 {
         int i, num, n, ret = 0;
         struct dlm_lock_resource *res;
         struct hlist_node *iter;
         struct hlist_head *bucket;
         int dropped;
 
         mlog(0, "Migrating locks from domain %s\n", dlm->name);
 
         num = 0;
         spin_lock(&dlm->spinlock);
         for (i = 0; i < DLM_HASH_BUCKETS; i++) {
 redo_bucket:
                 n = 0;
                 bucket = dlm_lockres_hash(dlm, i);
                 iter = bucket->first;
                 while (iter) {
                         n++;
                         res = hlist_entry(iter, struct dlm_lock_resource,
                                           hash_node);
                         dlm_lockres_get(res);
                         /* migrate, if necessary.  this will drop the dlm
                          * spinlock and retake it if it does migration. */
                         dropped = dlm_empty_lockres(dlm, res);
 
                         spin_lock(&res->spinlock);
                         __dlm_lockres_calc_usage(dlm, res);
                         iter = res->hash_node.next;
                         spin_unlock(&res->spinlock);
 
                         dlm_lockres_put(res);
 
                         if (dropped)
                                 goto redo_bucket;
                 }
                 cond_resched_lock(&dlm->spinlock);
                 num += n;
                 mlog(0, "%s: touched %d lockreses in bucket %d "
                      "(tot=%d)\n", dlm->name, n, i, num);
         }
         spin_unlock(&dlm->spinlock);
         wake_up(&dlm->dlm_thread_wq);
 
         /* let the dlm thread take care of purging, keep scanning until
          * nothing remains in the hash */
         if (num) {
                 mlog(0, "%s: %d lock resources in hash last pass\n",
                      dlm->name, num);
                 ret = -EAGAIN;
         }
         mlog(0, "DONE Migrating locks from domain %s\n", dlm->name);
         return ret;
 }
 
 static int dlm_no_joining_node(struct dlm_ctxt *dlm)
 {
         int ret;
 
         spin_lock(&dlm->spinlock);
         ret = dlm->joining_node == DLM_LOCK_RES_OWNER_UNKNOWN;
         spin_unlock(&dlm->spinlock);
 
         return ret;
 }
 
 static void dlm_mark_domain_leaving(struct dlm_ctxt *dlm)
 {
         /* Yikes, a double spinlock! I need domain_lock for the dlm
          * state and the dlm spinlock for join state... Sorry! */
 again:
         spin_lock(&dlm_domain_lock);
         spin_lock(&dlm->spinlock);
 
         if (dlm->joining_node != DLM_LOCK_RES_OWNER_UNKNOWN) {
                 mlog(0, "Node %d is joining, we wait on it.\n",
                           dlm->joining_node);
                 spin_unlock(&dlm->spinlock);
                 spin_unlock(&dlm_domain_lock);
 
                 wait_event(dlm->dlm_join_events, dlm_no_joining_node(dlm));
                 goto again;
         }
 
         dlm->dlm_state = DLM_CTXT_LEAVING;
         spin_unlock(&dlm->spinlock);
         spin_unlock(&dlm_domain_lock);
 }
 
 static void __dlm_print_nodes(struct dlm_ctxt *dlm)
 {
         int node = -1;
 
         assert_spin_locked(&dlm->spinlock);
 
         printk(KERN_INFO "ocfs2_dlm: Nodes in domain (\"%s\"): ", dlm->name);
 
         while ((node = find_next_bit(dlm->domain_map, O2NM_MAX_NODES,
                                      node + 1)) < O2NM_MAX_NODES) {
                 printk("%d ", node);
         }
         printk("\n");
 }
 
 static int dlm_exit_domain_handler(struct o2net_msg *msg, u32 len, void *data,
                                    void **ret_data)
 {
         struct dlm_ctxt *dlm = data;
         unsigned int node;
         struct dlm_exit_domain *exit_msg = (struct dlm_exit_domain *) msg->buf;
 
         mlog_entry("%p %u %p", msg, len, data);
 
         if (!dlm_grab(dlm))
                 return 0;
 
         node = exit_msg->node_idx;
 
         printk(KERN_INFO "ocfs2_dlm: Node %u leaves domain %s\n", node, dlm->name);
 
         spin_lock(&dlm->spinlock);
         clear_bit(node, dlm->domain_map);
         __dlm_print_nodes(dlm);
 
         /* notify anything attached to the heartbeat events */
         dlm_hb_event_notify_attached(dlm, node, 0);
 
         spin_unlock(&dlm->spinlock);
 
         dlm_put(dlm);
 
         return 0;
 }
 
 static int dlm_send_one_domain_exit(struct dlm_ctxt *dlm,
                                     unsigned int node)
 {
         int status;
         struct dlm_exit_domain leave_msg;
 
         mlog(0, "Asking node %u if we can leave the domain %s me = %u\n",
                   node, dlm->name, dlm->node_num);
 
         memset(&leave_msg, 0, sizeof(leave_msg));
         leave_msg.node_idx = dlm->node_num;
 
         status = o2net_send_message(DLM_EXIT_DOMAIN_MSG, dlm->key,
                                     &leave_msg, sizeof(leave_msg), node,
                                     NULL);
 
         mlog(0, "status return %d from o2net_send_message\n", status);
 
         return status;
 }
 
 
 static void dlm_leave_domain(struct dlm_ctxt *dlm)
 {
         int node, clear_node, status;
 
         /* At this point we've migrated away all our locks and won't
          * accept mastership of new ones. The dlm is responsible for
          * almost nothing now. We make sure not to confuse any joining
          * nodes and then commence shutdown procedure. */
 
         spin_lock(&dlm->spinlock);
         /* Clear ourselves from the domain map */
         clear_bit(dlm->node_num, dlm->domain_map);
         while ((node = find_next_bit(dlm->domain_map, O2NM_MAX_NODES,
                                      0)) < O2NM_MAX_NODES) {
                 /* Drop the dlm spinlock. This is safe wrt the domain_map.
                  * -nodes cannot be added now as the
                  *   query_join_handlers knows to respond with OK_NO_MAP
                  * -we catch the right network errors if a node is
                  *   removed from the map while we're sending him the
                  *   exit message. */
                 spin_unlock(&dlm->spinlock);
 
                 clear_node = 1;
 
                 status = dlm_send_one_domain_exit(dlm, node);
                 if (status < 0 &&
                     status != -ENOPROTOOPT &&
                     status != -ENOTCONN) {
                         mlog(ML_NOTICE, "Error %d sending domain exit message "
                              "to node %d\n", status, node);
 
                         /* Not sure what to do here but lets sleep for
                          * a bit in case this was a transient
                          * error... */
                         msleep(DLM_DOMAIN_BACKOFF_MS);
                         clear_node = 0;
                 }
 
                 spin_lock(&dlm->spinlock);
                 /* If we're not clearing the node bit then we intend
                  * to loop back around to try again. */
                 if (clear_node)
                         clear_bit(node, dlm->domain_map);
         }
         spin_unlock(&dlm->spinlock);
 }
 
 int dlm_joined(struct dlm_ctxt *dlm)
 {
         int ret = 0;
 
         spin_lock(&dlm_domain_lock);
 
         if (dlm->dlm_state == DLM_CTXT_JOINED)
                 ret = 1;
 
         spin_unlock(&dlm_domain_lock);
 
         return ret;
 }
 
 int dlm_shutting_down(struct dlm_ctxt *dlm)
 {
         int ret = 0;
 
         spin_lock(&dlm_domain_lock);
 
         if (dlm->dlm_state == DLM_CTXT_IN_SHUTDOWN)
                 ret = 1;
 
         spin_unlock(&dlm_domain_lock);
 
         return ret;
 }
 
 void dlm_unregister_domain(struct dlm_ctxt *dlm)
 {
         int leave = 0;
         struct dlm_lock_resource *res;
 
         spin_lock(&dlm_domain_lock);
         BUG_ON(dlm->dlm_state != DLM_CTXT_JOINED);
         BUG_ON(!dlm->num_joins);
 
         dlm->num_joins--;
         if (!dlm->num_joins) {
                 /* We mark it "in shutdown" now so new register
                  * requests wait until we've completely left the
                  * domain. Don't use DLM_CTXT_LEAVING yet as we still
                  * want new domain joins to communicate with us at
                  * least until we've completed migration of our
                  * resources. */
                 dlm->dlm_state = DLM_CTXT_IN_SHUTDOWN;
                 leave = 1;
         }
         spin_unlock(&dlm_domain_lock);
 
         if (leave) {
                 mlog(0, "shutting down domain %s\n", dlm->name);
 
                 /* We changed dlm state, notify the thread */
                 dlm_kick_thread(dlm, NULL);
 
                 while (dlm_migrate_all_locks(dlm)) {
                         /* Give dlm_thread time to purge the lockres' */
                         msleep(500);
                         mlog(0, "%s: more migration to do\n", dlm->name);
                 }
 
                 /* This list should be empty. If not, print remaining lockres */
                 if (!list_empty(&dlm->tracking_list)) {
                         mlog(ML_ERROR, "Following lockres' are still on the "
                              "tracking list:\n");
                         list_for_each_entry(res, &dlm->tracking_list, tracking)
                                 dlm_print_one_lock_resource(res);
                 }
 
                 dlm_mark_domain_leaving(dlm);
                 dlm_leave_domain(dlm);
                 dlm_complete_dlm_shutdown(dlm);
         }
         dlm_put(dlm);
 }
 EXPORT_SYMBOL_GPL(dlm_unregister_domain);
 
 static int dlm_query_join_proto_check(char *proto_type, int node,
                                       struct dlm_protocol_version *ours,
                                       struct dlm_protocol_version *request)
 {
         int rc;
         struct dlm_protocol_version proto = *request;
 
         if (!dlm_protocol_compare(ours, &proto)) {
                 mlog(0,
                      "node %u wanted to join with %s locking protocol "
                      "%u.%u, we respond with %u.%u\n",
                      node, proto_type,
                      request->pv_major,
                      request->pv_minor,
                      proto.pv_major, proto.pv_minor);
                 request->pv_minor = proto.pv_minor;
                 rc = 0;
         } else {
                 mlog(ML_NOTICE,
                      "Node %u wanted to join with %s locking "
                      "protocol %u.%u, but we have %u.%u, disallowing\n",
                      node, proto_type,
                      request->pv_major,
                      request->pv_minor,
                      ours->pv_major,
                      ours->pv_minor);
                 rc = 1;
         }
 
         return rc;
 }
 
 /*
  * struct dlm_query_join_packet is made up of four one-byte fields.  They
  * are effectively in big-endian order already.  However, little-endian
  * machines swap them before putting the packet on the wire (because
  * query_join's response is a status, and that status is treated as a u32
  * on the wire).  Thus, a big-endian and little-endian machines will treat
  * this structure differently.
  *
  * The solution is to have little-endian machines swap the structure when
  * converting from the structure to the u32 representation.  This will
  * result in the structure having the correct format on the wire no matter
  * the host endian format.
  */
 static void dlm_query_join_packet_to_wire(struct dlm_query_join_packet *packet,
                                           u32 *wire)
 {
         union dlm_query_join_response response;
 
         response.packet = *packet;
         *wire = cpu_to_be32(response.intval);
 }
 
 static void dlm_query_join_wire_to_packet(u32 wire,
                                           struct dlm_query_join_packet *packet)
 {
         union dlm_query_join_response response;
 
         response.intval = cpu_to_be32(wire);
         *packet = response.packet;
 }
 
 static int dlm_query_join_handler(struct o2net_msg *msg, u32 len, void *data,
                                   void **ret_data)
 {
         struct dlm_query_join_request *query;
         struct dlm_query_join_packet packet = {
                 .code = JOIN_DISALLOW,
         };
         struct dlm_ctxt *dlm = NULL;
         u32 response;
         u8 nodenum;
 
         query = (struct dlm_query_join_request *) msg->buf;
 
         mlog(0, "node %u wants to join domain %s\n", query->node_idx,
                   query->domain);
 
         /*
          * If heartbeat doesn't consider the node live, tell it
          * to back off and try again.  This gives heartbeat a chance
          * to catch up.
          */
         if (!o2hb_check_node_heartbeating(query->node_idx)) {
                 mlog(0, "node %u is not in our live map yet\n",
                      query->node_idx);
 
                 packet.code = JOIN_DISALLOW;
                 goto respond;
         }
 
         packet.code = JOIN_OK_NO_MAP;
 
         spin_lock(&dlm_domain_lock);
         dlm = __dlm_lookup_domain_full(query->domain, query->name_len);
         if (!dlm)
                 goto unlock_respond;
 
         /*
          * There is a small window where the joining node may not see the
          * node(s) that just left but still part of the cluster. DISALLOW
          * join request if joining node has different node map.
          */
         nodenum=0;
         while (nodenum < O2NM_MAX_NODES) {
                 if (test_bit(nodenum, dlm->domain_map)) {
                         if (!byte_test_bit(nodenum, query->node_map)) {
                                 mlog(0, "disallow join as node %u does not "
                                      "have node %u in its nodemap\n",
                                      query->node_idx, nodenum);
                                 packet.code = JOIN_DISALLOW;
                                 goto unlock_respond;
                         }
                 }
                 nodenum++;
         }
 
         /* Once the dlm ctxt is marked as leaving then we don't want
          * to be put in someone's domain map. 
          * Also, explicitly disallow joining at certain troublesome
          * times (ie. during recovery). */
         if (dlm && dlm->dlm_state != DLM_CTXT_LEAVING) {
                 int bit = query->node_idx;
                 spin_lock(&dlm->spinlock);
 
                 if (dlm->dlm_state == DLM_CTXT_NEW &&
                     dlm->joining_node == DLM_LOCK_RES_OWNER_UNKNOWN) {
                         /*If this is a brand new context and we
                          * haven't started our join process yet, then
                          * the other node won the race. */
                         packet.code = JOIN_OK_NO_MAP;
                 } else if (dlm->joining_node != DLM_LOCK_RES_OWNER_UNKNOWN) {
                         /* Disallow parallel joins. */
                         packet.code = JOIN_DISALLOW;
                 } else if (dlm->reco.state & DLM_RECO_STATE_ACTIVE) {
                         mlog(0, "node %u trying to join, but recovery "
                              "is ongoing.\n", bit);
                         packet.code = JOIN_DISALLOW;
                 } else if (test_bit(bit, dlm->recovery_map)) {
                         mlog(0, "node %u trying to join, but it "
                              "still needs recovery.\n", bit);
                         packet.code = JOIN_DISALLOW;
                 } else if (test_bit(bit, dlm->domain_map)) {
                         mlog(0, "node %u trying to join, but it "
                              "is still in the domain! needs recovery?\n",
                              bit);
                         packet.code = JOIN_DISALLOW;
                 } else {
                         /* Alright we're fully a part of this domain
                          * so we keep some state as to who's joining
                          * and indicate to him that needs to be fixed
                          * up. */
 
                         /* Make sure we speak compatible locking protocols.  */
                         if (dlm_query_join_proto_check("DLM", bit,
                                                        &dlm->dlm_locking_proto,
                                                        &query->dlm_proto)) {
                                 packet.code = JOIN_PROTOCOL_MISMATCH;
                         } else if (dlm_query_join_proto_check("fs", bit,
                                                               &dlm->fs_locking_proto,
                                                               &query->fs_proto)) {
                                 packet.code = JOIN_PROTOCOL_MISMATCH;
                         } else {
                                 packet.dlm_minor = query->dlm_proto.pv_minor;
                                 packet.fs_minor = query->fs_proto.pv_minor;
                                 packet.code = JOIN_OK;
                                 __dlm_set_joining_node(dlm, query->node_idx);
                         }
                 }
 
                 spin_unlock(&dlm->spinlock);
         }
 unlock_respond:
         spin_unlock(&dlm_domain_lock);
 
 respond:
         mlog(0, "We respond with %u\n", packet.code);
 
         dlm_query_join_packet_to_wire(&packet, &response);
         return response;
 }
 
 static int dlm_assert_joined_handler(struct o2net_msg *msg, u32 len, void *data,
                                      void **ret_data)
 {
         struct dlm_assert_joined *assert;
         struct dlm_ctxt *dlm = NULL;
 
         assert = (struct dlm_assert_joined *) msg->buf;
 
         mlog(0, "node %u asserts join on domain %s\n", assert->node_idx,
                   assert->domain);
 
         spin_lock(&dlm_domain_lock);
         dlm = __dlm_lookup_domain_full(assert->domain, assert->name_len);
         /* XXX should we consider no dlm ctxt an error? */
         if (dlm) {
                 spin_lock(&dlm->spinlock);
 
                 /* Alright, this node has officially joined our
                  * domain. Set him in the map and clean up our
                  * leftover join state. */
                 BUG_ON(dlm->joining_node != assert->node_idx);
                 set_bit(assert->node_idx, dlm->domain_map);
                 __dlm_set_joining_node(dlm, DLM_LOCK_RES_OWNER_UNKNOWN);
 
                 printk(KERN_INFO "ocfs2_dlm: Node %u joins domain %s\n",
                        assert->node_idx, dlm->name);
                 __dlm_print_nodes(dlm);
 
                 /* notify anything attached to the heartbeat events */
                 dlm_hb_event_notify_attached(dlm, assert->node_idx, 1);
 
                 spin_unlock(&dlm->spinlock);
         }
         spin_unlock(&dlm_domain_lock);
 
         return 0;
 }
 
 static int dlm_cancel_join_handler(struct o2net_msg *msg, u32 len, void *data,
                                    void **ret_data)
 {
         struct dlm_cancel_join *cancel;
         struct dlm_ctxt *dlm = NULL;
 
         cancel = (struct dlm_cancel_join *) msg->buf;
 
         mlog(0, "node %u cancels join on domain %s\n", cancel->node_idx,
                   cancel->domain);
 
         spin_lock(&dlm_domain_lock);
         dlm = __dlm_lookup_domain_full(cancel->domain, cancel->name_len);
 
         if (dlm) {
                 spin_lock(&dlm->spinlock);
 
                 /* Yikes, this guy wants to cancel his join. No
                  * problem, we simply cleanup our join state. */
                 BUG_ON(dlm->joining_node != cancel->node_idx);
                 __dlm_set_joining_node(dlm, DLM_LOCK_RES_OWNER_UNKNOWN);
 
                 spin_unlock(&dlm->spinlock);
         }
         spin_unlock(&dlm_domain_lock);
 
         return 0;
 }
 
 static int dlm_send_one_join_cancel(struct dlm_ctxt *dlm,
                                     unsigned int node)
 {
         int status;
         struct dlm_cancel_join cancel_msg;
 
         memset(&cancel_msg, 0, sizeof(cancel_msg));
         cancel_msg.node_idx = dlm->node_num;
         cancel_msg.name_len = strlen(dlm->name);
         memcpy(cancel_msg.domain, dlm->name, cancel_msg.name_len);
 
         status = o2net_send_message(DLM_CANCEL_JOIN_MSG, DLM_MOD_KEY,
                                     &cancel_msg, sizeof(cancel_msg), node,
                                     NULL);
         if (status < 0) {
                 mlog_errno(status);
                 goto bail;
         }
 
 bail:
         return status;
 }
 
 /* map_size should be in bytes. */
 static int dlm_send_join_cancels(struct dlm_ctxt *dlm,
                                  unsigned long *node_map,
                                  unsigned int map_size)
 {
         int status, tmpstat;
         unsigned int node;
 
         if (map_size != (BITS_TO_LONGS(O2NM_MAX_NODES) *
                          sizeof(unsigned long))) {
                 mlog(ML_ERROR,
                      "map_size %u != BITS_TO_LONGS(O2NM_MAX_NODES) %u\n",
                      map_size, (unsigned)BITS_TO_LONGS(O2NM_MAX_NODES));
                 return -EINVAL;
         }
 
         status = 0;
         node = -1;
         while ((node = find_next_bit(node_map, O2NM_MAX_NODES,
                                      node + 1)) < O2NM_MAX_NODES) {
                 if (node == dlm->node_num)
                         continue;
 
                 tmpstat = dlm_send_one_join_cancel(dlm, node);
                 if (tmpstat) {
                         mlog(ML_ERROR, "Error return %d cancelling join on "
                              "node %d\n", tmpstat, node);
                         if (!status)
                                 status = tmpstat;
                }
        }

        if (status)
                mlog_errno(status);
        return status;
}

static int dlm_request_join(struct dlm_ctxt *dlm,
                            int node,
                            enum dlm_query_join_response_code *response)
{
        int status;
        struct dlm_query_join_request join_msg;
        struct dlm_query_join_packet packet;
        u32 join_resp;

        mlog(0, "querying node %d\n", node);

        memset(&join_msg, 0, sizeof(join_msg));
        join_msg.node_idx = dlm->node_num;
        join_msg.name_len = strlen(dlm->name);
        memcpy(join_msg.domain, dlm->name, join_msg.name_len);
        join_msg.dlm_proto = dlm->dlm_locking_proto;
        join_msg.fs_proto = dlm->fs_locking_proto;

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

        status = o2net_send_message(DLM_QUERY_JOIN_MSG, DLM_MOD_KEY, &join_msg,
                                    sizeof(join_msg), node,
                                    &join_resp);
        if (status < 0 && status != -ENOPROTOOPT) {
                mlog_errno(status);
                goto bail;
        }
        dlm_query_join_wire_to_packet(join_resp, &packet);

        /* -ENOPROTOOPT from the net code means the other side isn't
            listening for our message type -- that's fine, it means
            his dlm isn't up, so we can consider him a 'yes' but not
            joined into the domain.  */
        if (status == -ENOPROTOOPT) {
                status = 0;
                *response = JOIN_OK_NO_MAP;
        } else if (packet.code == JOIN_DISALLOW ||
                   packet.code == JOIN_OK_NO_MAP) {
                *response = packet.code;
        } else if (packet.code == JOIN_PROTOCOL_MISMATCH) {
                mlog(ML_NOTICE,
                     "This node requested DLM locking protocol %u.%u and "
                     "filesystem locking protocol %u.%u.  At least one of "
                     "the protocol versions on node %d is not compatible, "
                     "disconnecting\n",
                     dlm->dlm_locking_proto.pv_major,
                     dlm->dlm_locking_proto.pv_minor,
                     dlm->fs_locking_proto.pv_major,
                     dlm->fs_locking_proto.pv_minor,
                     node);
                status = -EPROTO;
                *response = packet.code;
        } else if (packet.code == JOIN_OK) {
                *response = packet.code;
                /* Use the same locking protocol as the remote node */
                dlm->dlm_locking_proto.pv_minor = packet.dlm_minor;
                dlm->fs_locking_proto.pv_minor = packet.fs_minor;
                mlog(0,
                     "Node %d responds JOIN_OK with DLM locking protocol "
                     "%u.%u and fs locking protocol %u.%u\n",
                     node,
                     dlm->dlm_locking_proto.pv_major,
                     dlm->dlm_locking_proto.pv_minor,
                     dlm->fs_locking_proto.pv_major,
                     dlm->fs_locking_proto.pv_minor);
        } else {
                status = -EINVAL;
                mlog(ML_ERROR, "invalid response %d from node %u\n",
                     packet.code, node);
        }

        mlog(0, "status %d, node %d response is %d\n", status, node,
             *response);

bail:
        return status;
}

static int dlm_send_one_join_assert(struct dlm_ctxt *dlm,
                                    unsigned int node)
{
        int status;
        struct dlm_assert_joined assert_msg;

        mlog(0, "Sending join assert to node %u\n", node);

        memset(&assert_msg, 0, sizeof(assert_msg));
        assert_msg.node_idx = dlm->node_num;
        assert_msg.name_len = strlen(dlm->name);
        memcpy(assert_msg.domain, dlm->name, assert_msg.name_len);

        status = o2net_send_message(DLM_ASSERT_JOINED_MSG, DLM_MOD_KEY,
                                    &assert_msg, sizeof(assert_msg), node,
                                    NULL);
        if (status < 0)
                mlog_errno(status);

        return status;
}

static void dlm_send_join_asserts(struct dlm_ctxt *dlm,
                                  unsigned long *node_map)
{
        int status, node, live;

        status = 0;
        node = -1;
        while ((node = find_next_bit(node_map, O2NM_MAX_NODES,
                                     node + 1)) < O2NM_MAX_NODES) {
                if (node == dlm->node_num)
                        continue;

                do {
                        /* It is very important that this message be
                         * received so we spin until either the node
                         * has died or it gets the message. */
                        status = dlm_send_one_join_assert(dlm, node);

                        spin_lock(&dlm->spinlock);
                        live = test_bit(node, dlm->live_nodes_map);
                        spin_unlock(&dlm->spinlock);

                        if (status) {
                                mlog(ML_ERROR, "Error return %d asserting "
                                     "join on node %d\n", status, node);

                                /* give us some time between errors... */
                                if (live)
                                        msleep(DLM_DOMAIN_BACKOFF_MS);
                        }
                } while (status && live);
        }
}

struct domain_join_ctxt {
        unsigned long live_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
        unsigned long yes_resp_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
};

static int dlm_should_restart_join(struct dlm_ctxt *dlm,
                                   struct domain_join_ctxt *ctxt,
                                   enum dlm_query_join_response_code response)
{
        int ret;

        if (response == JOIN_DISALLOW) {
                mlog(0, "Latest response of disallow -- should restart\n");
                return 1;
        }

        spin_lock(&dlm->spinlock);
        /* For now, we restart the process if the node maps have
         * changed at all */
        ret = memcmp(ctxt->live_map, dlm->live_nodes_map,
                     sizeof(dlm->live_nodes_map));
        spin_unlock(&dlm->spinlock);

        if (ret)
                mlog(0, "Node maps changed -- should restart\n");

        return ret;
}

static int dlm_try_to_join_domain(struct dlm_ctxt *dlm)
{
        int status = 0, tmpstat, node;
        struct domain_join_ctxt *ctxt;
        enum dlm_query_join_response_code response = JOIN_DISALLOW;

        mlog_entry("%p", dlm);

        ctxt = kzalloc(sizeof(*ctxt), GFP_KERNEL);
        if (!ctxt) {
                status = -ENOMEM;
                mlog_errno(status);
                goto bail;
        }

        /* group sem locking should work for us here -- we're already
         * registered for heartbeat events so filling this should be
         * atomic wrt getting those handlers called. */
        o2hb_fill_node_map(dlm->live_nodes_map, sizeof(dlm->live_nodes_map));

        spin_lock(&dlm->spinlock);
        memcpy(ctxt->live_map, dlm->live_nodes_map, sizeof(ctxt->live_map));

        __dlm_set_joining_node(dlm, dlm->node_num);

        spin_unlock(&dlm->spinlock);

        node = -1;
        while ((node = find_next_bit(ctxt->live_map, O2NM_MAX_NODES,
                                     node + 1)) < O2NM_MAX_NODES) {
                if (node == dlm->node_num)
                        continue;

                status = dlm_request_join(dlm, node, &response);
                if (status < 0) {
                        mlog_errno(status);
                        goto bail;
                }

                /* Ok, either we got a response or the node doesn't have a
                 * dlm up. */
                if (response == JOIN_OK)
                        set_bit(node, ctxt->yes_resp_map);

                if (dlm_should_restart_join(dlm, ctxt, response)) {
                        status = -EAGAIN;
                        goto bail;
                }
        }

        mlog(0, "Yay, done querying nodes!\n");

        /* Yay, everyone agree's we can join the domain. My domain is
         * comprised of all nodes who were put in the
         * yes_resp_map. Copy that into our domain map and send a join
         * assert message to clean up everyone elses state. */
        spin_lock(&dlm->spinlock);
        memcpy(dlm->domain_map, ctxt->yes_resp_map,
               sizeof(ctxt->yes_resp_map));
        set_bit(dlm->node_num, dlm->domain_map);
        spin_unlock(&dlm->spinlock);

        dlm_send_join_asserts(dlm, ctxt->yes_resp_map);

        /* Joined state *must* be set before the joining node
         * information, otherwise the query_join handler may read no
         * current joiner but a state of NEW and tell joining nodes
         * we're not in the domain. */
        spin_lock(&dlm_domain_lock);
        dlm->dlm_state = DLM_CTXT_JOINED;
        dlm->num_joins++;
        spin_unlock(&dlm_domain_lock);

bail:
        spin_lock(&dlm->spinlock);
        __dlm_set_joining_node(dlm, DLM_LOCK_RES_OWNER_UNKNOWN);
        if (!status)
                __dlm_print_nodes(dlm);
        spin_unlock(&dlm->spinlock);

        if (ctxt) {
                /* Do we need to send a cancel message to any nodes? */
                if (status < 0) {
                        tmpstat = dlm_send_join_cancels(dlm,
                                                        ctxt->yes_resp_map,
                                                        sizeof(ctxt->yes_resp_map));
                        if (tmpstat < 0)
                                mlog_errno(tmpstat);
                }
                kfree(ctxt);
        }

        mlog(0, "returning %d\n", status);
        return status;
}

static void dlm_unregister_domain_handlers(struct dlm_ctxt *dlm)
{
        o2hb_unregister_callback(NULL, &dlm->dlm_hb_up);
        o2hb_unregister_callback(NULL, &dlm->dlm_hb_down);
        o2net_unregister_handler_list(&dlm->dlm_domain_handlers);
}

static int dlm_register_domain_handlers(struct dlm_ctxt *dlm)
{
        int status;

        mlog(0, "registering handlers.\n");

        o2hb_setup_callback(&dlm->dlm_hb_down, O2HB_NODE_DOWN_CB,
                            dlm_hb_node_down_cb, dlm, DLM_HB_NODE_DOWN_PRI);
        status = o2hb_register_callback(NULL, &dlm->dlm_hb_down);
        if (status)
                goto bail;

        o2hb_setup_callback(&dlm->dlm_hb_up, O2HB_NODE_UP_CB,
                            dlm_hb_node_up_cb, dlm, DLM_HB_NODE_UP_PRI);
        status = o2hb_register_callback(NULL, &dlm->dlm_hb_up);
        if (status)
                goto bail;

        status = o2net_register_handler(DLM_MASTER_REQUEST_MSG, dlm->key,
                                        sizeof(struct dlm_master_request),
                                        dlm_master_request_handler,
                                        dlm, NULL, &dlm->dlm_domain_handlers);
        if (status)
                goto bail;

        status = o2net_register_handler(DLM_ASSERT_MASTER_MSG, dlm->key,
                                        sizeof(struct dlm_assert_master),
                                        dlm_assert_master_handler,
                                        dlm, dlm_assert_master_post_handler,
                                        &dlm->dlm_domain_handlers);
        if (status)
                goto bail;

        status = o2net_register_handler(DLM_CREATE_LOCK_MSG, dlm->key,
                                        sizeof(struct dlm_create_lock),
                                        dlm_create_lock_handler,
                                        dlm, NULL, &dlm->dlm_domain_handlers);
        if (status)
                goto bail;

        status = o2net_register_handler(DLM_CONVERT_LOCK_MSG, dlm->key,
                                        DLM_CONVERT_LOCK_MAX_LEN,
                                        dlm_convert_lock_handler,
                                        dlm, NULL, &dlm->dlm_domain_handlers);
        if (status)
                goto bail;

        status = o2net_register_handler(DLM_UNLOCK_LOCK_MSG, dlm->key,
                                        DLM_UNLOCK_LOCK_MAX_LEN,
                                        dlm_unlock_lock_handler,
                                        dlm, NULL, &dlm->dlm_domain_handlers);
        if (status)
                goto bail;

        status = o2net_register_handler(DLM_PROXY_AST_MSG, dlm->key,
                                        DLM_PROXY_AST_MAX_LEN,
                                        dlm_proxy_ast_handler,
                                        dlm, NULL, &dlm->dlm_domain_handlers);
        if (status)
                goto bail;

        status = o2net_register_handler(DLM_EXIT_DOMAIN_MSG, dlm->key,
                                        sizeof(struct dlm_exit_domain),
                                        dlm_exit_domain_handler,
                                        dlm, NULL, &dlm->dlm_domain_handlers);
        if (status)
                goto bail;

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

        status = o2net_register_handler(DLM_MIGRATE_REQUEST_MSG, dlm->key,
                                        sizeof(struct dlm_migrate_request),
                                        dlm_migrate_request_handler,
                                        dlm, NULL, &dlm->dlm_domain_handlers);
        if (status)
                goto bail;

        status = o2net_register_handler(DLM_MIG_LOCKRES_MSG, dlm->key,
                                        DLM_MIG_LOCKRES_MAX_LEN,
                                        dlm_mig_lockres_handler,
                                        dlm, NULL, &dlm->dlm_domain_handlers);
        if (status)
                goto bail;

        status = o2net_register_handler(DLM_MASTER_REQUERY_MSG, dlm->key,
                                        sizeof(struct dlm_master_requery),
                                        dlm_master_requery_handler,
                                        dlm, NULL, &dlm->dlm_domain_handlers);
        if (status)
                goto bail;

        status = o2net_register_handler(DLM_LOCK_REQUEST_MSG, dlm->key,
                                        sizeof(struct dlm_lock_request),
                                        dlm_request_all_locks_handler,
                                        dlm, NULL, &dlm->dlm_domain_handlers);
        if (status)
                goto bail;

        status = o2net_register_handler(DLM_RECO_DATA_DONE_MSG, dlm->key,
                                        sizeof(struct dlm_reco_data_done),
                                        dlm_reco_data_done_handler,
                                        dlm, NULL, &dlm->dlm_domain_handlers);
        if (status)
                goto bail;

        status = o2net_register_handler(DLM_BEGIN_RECO_MSG, dlm->key,
                                        sizeof(struct dlm_begin_reco),
                                        dlm_begin_reco_handler,
                                        dlm, NULL, &dlm->dlm_domain_handlers);
        if (status)
                goto bail;

        status = o2net_register_handler(DLM_FINALIZE_RECO_MSG, dlm->key,
                                        sizeof(struct dlm_finalize_reco),
                                        dlm_finalize_reco_handler,
                                        dlm, NULL, &dlm->dlm_domain_handlers);
        if (status)
                goto bail;

bail:
        if (status)
                dlm_unregister_domain_handlers(dlm);

        return status;
}

static int dlm_join_domain(struct dlm_ctxt *dlm)
{
        int status;
        unsigned int backoff;
        unsigned int total_backoff = 0;

        BUG_ON(!dlm);

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

        status = dlm_register_domain_handlers(dlm);
        if (status) {
                mlog_errno(status);
                goto bail;
        }

        status = dlm_debug_init(dlm);
        if (status < 0) {
                mlog_errno(status);
                goto bail;
        }

        status = dlm_launch_thread(dlm);
        if (status < 0) {
                mlog_errno(status);
                goto bail;
        }

        status = dlm_launch_recovery_thread(dlm);
        if (status < 0) {
                mlog_errno(status);
                goto bail;
        }

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

        do {
                status = dlm_try_to_join_domain(dlm);

                /* If we're racing another node to the join, then we
                 * need to back off temporarily and let them
                 * complete. */
#define        DLM_JOIN_TIMEOUT_MSECS        90000
                if (status == -EAGAIN) {
                        if (signal_pending(current)) {
                                status = -ERESTARTSYS;
                                goto bail;
                        }

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

                        /*
                         * <chip> After you!
                         * <dale> No, after you!
                         * <chip> I insist!
                         * <dale> But you first!
                         * ...
                         */
                        backoff = (unsigned int)(jiffies & 0x3);
                        backoff *= DLM_DOMAIN_BACKOFF_MS;
                        total_backoff += backoff;
                        mlog(0, "backoff %d\n", backoff);
                        msleep(backoff);
                }
        } while (status == -EAGAIN);

        if (status < 0) {
                mlog_errno(status);
                goto bail;
        }

        status = 0;
bail:
        wake_up(&dlm_domain_events);

        if (status) {
                dlm_unregister_domain_handlers(dlm);
                dlm_debug_shutdown(dlm);
                dlm_complete_thread(dlm);
                dlm_complete_recovery_thread(dlm);
                dlm_destroy_dlm_worker(dlm);
        }

        return status;
}

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

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

        dlm->name = kmalloc(strlen(domain) + 1, GFP_KERNEL);
        if (dlm->name == NULL) {
                mlog_errno(-ENOMEM);
                kfree(dlm);
                dlm = NULL;
                goto leave;
        }

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

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

        strcpy(dlm->name, domain);
        dlm->key = key;
        dlm->node_num = o2nm_this_node();

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

        spin_lock_init(&dlm->spinlock);
        spin_lock_init(&dlm->master_lock);
        spin_lock_init(&dlm->ast_lock);
        INIT_LIST_HEAD(&dlm->list);
        INIT_LIST_HEAD(&dlm->dirty_list);
        INIT_LIST_HEAD(&dlm->reco.resources);
        INIT_LIST_HEAD(&dlm->reco.received);
        INIT_LIST_HEAD(&dlm->reco.node_data);
        INIT_LIST_HEAD(&dlm->purge_list);
        INIT_LIST_HEAD(&dlm->dlm_domain_handlers);
        INIT_LIST_HEAD(&dlm->tracking_list);
        dlm->reco.state = 0;

        INIT_LIST_HEAD(&dlm->pending_asts);
        INIT_LIST_HEAD(&dlm->pending_basts);

        mlog(0, "dlm->recovery_map=%p, &(dlm->recovery_map[0])=%p\n",
                  dlm->recovery_map, &(dlm->recovery_map[0]));

        memset(dlm->recovery_map, 0, sizeof(dlm->recovery_map));
        memset(dlm->live_nodes_map, 0, sizeof(dlm->live_nodes_map));
        memset(dlm->domain_map, 0, sizeof(dlm->domain_map));

        dlm->dlm_thread_task = NULL;
        dlm->dlm_reco_thread_task = NULL;
        dlm->dlm_worker = NULL;
        init_waitqueue_head(&dlm->dlm_thread_wq);
        init_waitqueue_head(&dlm->dlm_reco_thread_wq);
        init_waitqueue_head(&dlm->reco.event);
        init_waitqueue_head(&dlm->ast_wq);
        init_waitqueue_head(&dlm->migration_wq);
        INIT_LIST_HEAD(&dlm->master_list);
        INIT_LIST_HEAD(&dlm->mle_hb_events);

        dlm->joining_node = DLM_LOCK_RES_OWNER_UNKNOWN;
        init_waitqueue_head(&dlm->dlm_join_events);

        dlm->reco.new_master = O2NM_INVALID_NODE_NUM;
        dlm->reco.dead_node = O2NM_INVALID_NODE_NUM;
        atomic_set(&dlm->local_resources, 0);
        atomic_set(&dlm->remote_resources, 0);
        atomic_set(&dlm->unknown_resources, 0);

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

        kref_init(&dlm->dlm_refs);
        dlm->dlm_state = DLM_CTXT_NEW;

        INIT_LIST_HEAD(&dlm->dlm_eviction_callbacks);

        mlog(0, "context init: refcount %u\n",
                  atomic_read(&dlm->dlm_refs.refcount));

leave:
        return dlm;
}

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

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

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

        return 0;
}

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

        if (strlen(domain) > O2NM_MAX_NAME_LEN) {
                ret = -ENAMETOOLONG;
                mlog(ML_ERROR, "domain name length too long\n");
                goto leave;
        }

        if (!o2hb_check_local_node_heartbeating()) {
                mlog(ML_ERROR, "the local node has not been configured, or is "
                     "not heartbeating\n");
                ret = -EPROTO;
                goto leave;
        }

        mlog(0, "register called for domain \"%s\"\n", domain);

retry:
        dlm = NULL;
        if (signal_pending(current)) {
                ret = -ERESTARTSYS;
                mlog_errno(ret);
                goto leave;
        }

        spin_lock(&dlm_domain_lock);

        dlm = __dlm_lookup_domain(domain);
        if (dlm) {
                if (dlm->dlm_state != DLM_CTXT_JOINED) {
                        spin_unlock(&dlm_domain_lock);

                        mlog(0, "This ctxt is not joined yet!\n");
                        wait_event_interruptible(dlm_domain_events,
                                                 dlm_wait_on_domain_helper(
                                                         domain));
                        goto retry;
                }

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

                __dlm_get(dlm);
                dlm->num_joins++;

                spin_unlock(&dlm_domain_lock);

                ret = 0;
                goto leave;
        }

        /* doesn't exist */
        if (!new_ctxt) {
                spin_unlock(&dlm_domain_lock);

                new_ctxt = dlm_alloc_ctxt(domain, key);
                if (new_ctxt)
                        goto retry;

                ret = -ENOMEM;
                mlog_errno(ret);
                goto leave;
        }

        /* a little variable switch-a-roo here... */
        dlm = new_ctxt;
        new_ctxt = NULL;

        /* add the new domain */
        list_add_tail(&dlm->list, &dlm_domains);
        spin_unlock(&dlm_domain_lock);

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

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

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

        ret = 0;
leave:
        if (new_ctxt)
                dlm_free_ctxt_mem(new_ctxt);

        if (ret < 0)
                dlm = ERR_PTR(ret);

        return dlm;
}
EXPORT_SYMBOL_GPL(dlm_register_domain);

static LIST_HEAD(dlm_join_handlers);

static void dlm_unregister_net_handlers(void)
{
        o2net_unregister_handler_list(&dlm_join_handlers);
}

static int dlm_register_net_handlers(void)
{
        int status = 0;

        status = o2net_register_handler(DLM_QUERY_JOIN_MSG, DLM_MOD_KEY,
                                        sizeof(struct dlm_query_join_request),
                                        dlm_query_join_handler,
                                        NULL, NULL, &dlm_join_handlers);
        if (status)
                goto bail;

        status = o2net_register_handler(DLM_ASSERT_JOINED_MSG, DLM_MOD_KEY,
                                        sizeof(struct dlm_assert_joined),
                                        dlm_assert_joined_handler,
                                        NULL, NULL, &dlm_join_handlers);
        if (status)
                goto bail;

        status = o2net_register_handler(DLM_CANCEL_JOIN_MSG, DLM_MOD_KEY,
                                        sizeof(struct dlm_cancel_join),
                                        dlm_cancel_join_handler,
                                        NULL, NULL, &dlm_join_handlers);

bail:
        if (status < 0)
                dlm_unregister_net_handlers();

        return status;
}

/* Domain eviction callback handling.
 *
 * The file system requires notification of node death *before* the
 * dlm completes it's recovery work, otherwise it may be able to
 * acquire locks on resources requiring recovery. Since the dlm can
 * evict a node from it's domain *before* heartbeat fires, a similar
 * mechanism is required. */

/* Eviction is not expected to happen often, so a per-domain lock is
 * not necessary. Eviction callbacks are allowed to sleep for short
 * periods of time. */
static DECLARE_RWSEM(dlm_callback_sem);

void dlm_fire_domain_eviction_callbacks(struct dlm_ctxt *dlm,
                                        int node_num)
{
        struct list_head *iter;
        struct dlm_eviction_cb *cb;

        down_read(&dlm_callback_sem);
        list_for_each(iter, &dlm->dlm_eviction_callbacks) {
                cb = list_entry(iter, struct dlm_eviction_cb, ec_item);

                cb->ec_func(node_num, cb->ec_data);
        }
        up_read(&dlm_callback_sem);
}

void dlm_setup_eviction_cb(struct dlm_eviction_cb *cb,
                           dlm_eviction_func *f,
                           void *data)
{
        INIT_LIST_HEAD(&cb->ec_item);
        cb->ec_func = f;
        cb->ec_data = data;
}
EXPORT_SYMBOL_GPL(dlm_setup_eviction_cb);

void dlm_register_eviction_cb(struct dlm_ctxt *dlm,
                              struct dlm_eviction_cb *cb)
{
        down_write(&dlm_callback_sem);
        list_add_tail(&cb->ec_item, &dlm->dlm_eviction_callbacks);
        up_write(&dlm_callback_sem);
}
EXPORT_SYMBOL_GPL(dlm_register_eviction_cb);

void dlm_unregister_eviction_cb(struct dlm_eviction_cb *cb)
{
        down_write(&dlm_callback_sem);
        list_del_init(&cb->ec_item);
        up_write(&dlm_callback_sem);
}
EXPORT_SYMBOL_GPL(dlm_unregister_eviction_cb);

static int __init dlm_init(void)
{
        int status;

        dlm_print_version();

        status = dlm_init_mle_cache();
        if (status) {
                mlog(ML_ERROR, "Could not create o2dlm_mle slabcache\n");
                goto error;
        }

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

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

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

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

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

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

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

module_init(dlm_init);
module_exit(dlm_exit);