1 files changed, 159 insertions, 97 deletions

diff --git a/fs/ocfs2/dlm/dlmdomain.c b/fs/ocfs2/dlm/dlmdomain.c
index 7e38a072d72..39efc5057a3 100644
--- a/fs/ocfs2/dlm/dlmdomain.c
+++ b/fs/ocfs2/dlm/dlmdomain.c
@@ -43,8 +43,6 @@
 #include "dlmdomain.h"
 #include "dlmdebug.h"
 
-#include "dlmver.h"
-
 #define MLOG_MASK_PREFIX (ML_DLM|ML_DLM_DOMAIN)
 #include "cluster/masklog.h"
 
@@ -132,10 +130,12 @@ static DECLARE_WAIT_QUEUE_HEAD(dlm_domain_events);
  * New in version 1.1:
  *	- Message DLM_QUERY_REGION added to support global heartbeat
  *	- Message DLM_QUERY_NODEINFO added to allow online node removes
+ * New in version 1.2:
+ * 	- Message DLM_BEGIN_EXIT_DOMAIN_MSG added to mark start of exit domain
  */
 static const struct dlm_protocol_version dlm_protocol = {
 	.pv_major = 1,
-	.pv_minor = 1,
+	.pv_minor = 2,
 };
 
 #define DLM_DOMAIN_BACKOFF_MS 200
@@ -155,16 +155,18 @@ static int dlm_protocol_compare(struct dlm_protocol_version *existing,
 
 static void dlm_unregister_domain_handlers(struct dlm_ctxt *dlm);
 
-void __dlm_unhash_lockres(struct dlm_lock_resource *lockres)
+void __dlm_unhash_lockres(struct dlm_ctxt *dlm, struct dlm_lock_resource *res)
 {
-	if (!hlist_unhashed(&lockres->hash_node)) {
-		hlist_del_init(&lockres->hash_node);
-		dlm_lockres_put(lockres);
-	}
+	if (hlist_unhashed(&res->hash_node))
+		return;
+
+	mlog(0, "%s: Unhash res %.*s\n", dlm->name, res->lockname.len,
+	     res->lockname.name);
+	hlist_del_init(&res->hash_node);
+	dlm_lockres_put(res);
 }
 
-void __dlm_insert_lockres(struct dlm_ctxt *dlm,
-		       struct dlm_lock_resource *res)
+void __dlm_insert_lockres(struct dlm_ctxt *dlm, struct dlm_lock_resource *res)
 {
 	struct hlist_head *bucket;
 	struct qstr *q;
@@ -178,6 +180,9 @@ void __dlm_insert_lockres(struct dlm_ctxt *dlm,
 	dlm_lockres_get(res);
 
 	hlist_add_head(&res->hash_node, bucket);
+
+	mlog(0, "%s: Hash res %.*s\n", dlm->name, res->lockname.len,
+	     res->lockname.name);
 }
 
 struct dlm_lock_resource * __dlm_lookup_lockres_full(struct dlm_ctxt *dlm,
@@ -186,17 +191,15 @@ struct dlm_lock_resource * __dlm_lookup_lockres_full(struct dlm_ctxt *dlm,
 						     unsigned int hash)
 {
 	struct hlist_head *bucket;
-	struct hlist_node *list;
+	struct dlm_lock_resource *res;
 
-	mlog_entry("%.*s\n", len, name);
+	mlog(0, "%.*s\n", len, name);
 
 	assert_spin_locked(&dlm->spinlock);
 
 	bucket = dlm_lockres_hash(dlm, hash);
 
-	hlist_for_each(list, bucket) {
-		struct dlm_lock_resource *res = hlist_entry(list,
-			struct dlm_lock_resource, hash_node);
+	hlist_for_each_entry(res, bucket, hash_node) {
 		if (res->lockname.name[0] != name[0])
 			continue;
 		if (unlikely(res->lockname.len != len))
@@ -222,7 +225,7 @@ struct dlm_lock_resource * __dlm_lookup_lockres(struct dlm_ctxt *dlm,
 {
 	struct dlm_lock_resource *res = NULL;
 
-	mlog_entry("%.*s\n", len, name);
+	mlog(0, "%.*s\n", len, name);
 
 	assert_spin_locked(&dlm->spinlock);
 
@@ -255,22 +258,19 @@ struct dlm_lock_resource * dlm_lookup_lockres(struct dlm_ctxt *dlm,
 
 static struct dlm_ctxt * __dlm_lookup_domain_full(const char *domain, int len)
 {
-	struct dlm_ctxt *tmp = NULL;
-	struct list_head *iter;
+	struct dlm_ctxt *tmp;
 
 	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);
+	list_for_each_entry(tmp, &dlm_domains, list) {
 		if (strlen(tmp->name) == len &&
 		    memcmp(tmp->name, domain, len)==0)
-			break;
-		tmp = NULL;
+			return tmp;
 	}
 
-	return tmp;
+	return NULL;
 }
 
 /* For null terminated domain strings ONLY */
@@ -312,9 +312,7 @@ static void dlm_free_ctxt_mem(struct dlm_ctxt *dlm)
 	if (dlm->master_hash)
 		dlm_free_pagevec((void **)dlm->master_hash, DLM_HASH_PAGES);
 
-	if (dlm->name)
-		kfree(dlm->name);
-
+	kfree(dlm->name);
 	kfree(dlm);
 }
 
@@ -361,25 +359,22 @@ static void __dlm_get(struct dlm_ctxt *dlm)
  * you shouldn't trust your pointer. */
 struct dlm_ctxt *dlm_grab(struct dlm_ctxt *dlm)
 {
-	struct list_head *iter;
-	struct dlm_ctxt *target = NULL;
+	struct dlm_ctxt *target;
+	struct dlm_ctxt *ret = NULL;
 
 	spin_lock(&dlm_domain_lock);
 
-	list_for_each(iter, &dlm_domains) {
-		target = list_entry (iter, struct dlm_ctxt, list);
-
+	list_for_each_entry(target, &dlm_domains, list) {
 		if (target == dlm) {
 			__dlm_get(target);
+			ret = target;
 			break;
 		}
-
-		target = NULL;
 	}
 
 	spin_unlock(&dlm_domain_lock);
 
-	return target;
+	return ret;
 }
 
 int dlm_domain_fully_joined(struct dlm_ctxt *dlm)
@@ -449,14 +444,18 @@ redo_bucket:
 			dropped = dlm_empty_lockres(dlm, res);
 
 			spin_lock(&res->spinlock);
-			__dlm_lockres_calc_usage(dlm, res);
-			iter = res->hash_node.next;
+			if (dropped)
+				__dlm_lockres_calc_usage(dlm, res);
+			else
+				iter = res->hash_node.next;
 			spin_unlock(&res->spinlock);
 
 			dlm_lockres_put(res);
 
-			if (dropped)
+			if (dropped) {
+				cond_resched_lock(&dlm->spinlock);
 				goto redo_bucket;
+			}
 		}
 		cond_resched_lock(&dlm->spinlock);
 		num += n;
@@ -486,6 +485,28 @@ static int dlm_no_joining_node(struct dlm_ctxt *dlm)
 	return ret;
 }
 
+static int dlm_begin_exit_domain_handler(struct o2net_msg *msg, u32 len,
+					 void *data, void **ret_data)
+{
+	struct dlm_ctxt *dlm = data;
+	unsigned int node;
+	struct dlm_exit_domain *exit_msg = (struct dlm_exit_domain *) msg->buf;
+
+	if (!dlm_grab(dlm))
+		return 0;
+
+	node = exit_msg->node_idx;
+	mlog(0, "%s: Node %u sent a begin exit domain message\n", dlm->name, node);
+
+	spin_lock(&dlm->spinlock);
+	set_bit(node, dlm->exit_domain_map);
+	spin_unlock(&dlm->spinlock);
+
+	dlm_put(dlm);
+
+	return 0;
+}
+
 static void dlm_mark_domain_leaving(struct dlm_ctxt *dlm)
 {
 	/* Yikes, a double spinlock! I need domain_lock for the dlm
@@ -511,17 +532,17 @@ again:
 
 static void __dlm_print_nodes(struct dlm_ctxt *dlm)
 {
-	int node = -1;
+	int node = -1, num = 0;
 
 	assert_spin_locked(&dlm->spinlock);
 
-	printk(KERN_NOTICE "o2dlm: Nodes in domain %s: ", dlm->name);
-
+	printk("( ");
 	while ((node = find_next_bit(dlm->domain_map, O2NM_MAX_NODES,
 				     node + 1)) < O2NM_MAX_NODES) {
 		printk("%d ", node);
+		++num;
 	}
-	printk("\n");
+	printk(") %u nodes\n", num);
 }
 
 static int dlm_exit_domain_handler(struct o2net_msg *msg, u32 len, void *data,
@@ -531,17 +552,17 @@ static int dlm_exit_domain_handler(struct o2net_msg *msg, u32 len, void *data,
 	unsigned int node;
 	struct dlm_exit_domain *exit_msg = (struct dlm_exit_domain *) msg->buf;
 
-	mlog_entry("%p %u %p", msg, len, data);
+	mlog(0, "%p %u %p", msg, len, data);
 
 	if (!dlm_grab(dlm))
 		return 0;
 
 	node = exit_msg->node_idx;
 
-	printk(KERN_NOTICE "o2dlm: Node %u leaves domain %s\n", node, dlm->name);
-
 	spin_lock(&dlm->spinlock);
 	clear_bit(node, dlm->domain_map);
+	clear_bit(node, dlm->exit_domain_map);
+	printk(KERN_NOTICE "o2dlm: Node %u leaves domain %s ", node, dlm->name);
 	__dlm_print_nodes(dlm);
 
 	/* notify anything attached to the heartbeat events */
@@ -554,29 +575,56 @@ static int dlm_exit_domain_handler(struct o2net_msg *msg, u32 len, void *data,
 	return 0;
 }
 
-static int dlm_send_one_domain_exit(struct dlm_ctxt *dlm,
+static int dlm_send_one_domain_exit(struct dlm_ctxt *dlm, u32 msg_type,
 				    unsigned int node)
 {
 	int status;
 	struct dlm_exit_domain leave_msg;
 
-	mlog(0, "Asking node %u if we can leave the domain %s me = %u\n",
-		  node, dlm->name, dlm->node_num);
+	mlog(0, "%s: Sending domain exit message %u to node %u\n", dlm->name,
+	     msg_type, node);
 
 	memset(&leave_msg, 0, sizeof(leave_msg));
 	leave_msg.node_idx = dlm->node_num;
 
-	status = o2net_send_message(DLM_EXIT_DOMAIN_MSG, dlm->key,
-				    &leave_msg, sizeof(leave_msg), node,
-				    NULL);
+	status = o2net_send_message(msg_type, dlm->key, &leave_msg,
+				    sizeof(leave_msg), node, NULL);
 	if (status < 0)
-		mlog(ML_ERROR, "Error %d when sending message %u (key 0x%x) to "
-		     "node %u\n", status, DLM_EXIT_DOMAIN_MSG, dlm->key, node);
-	mlog(0, "status return %d from o2net_send_message\n", status);
+		mlog(ML_ERROR, "Error %d sending domain exit message %u "
+		     "to node %u on domain %s\n", status, msg_type, node,
+		     dlm->name);
 
 	return status;
 }
 
+static void dlm_begin_exit_domain(struct dlm_ctxt *dlm)
+{
+	int node = -1;
+
+	/* Support for begin exit domain was added in 1.2 */
+	if (dlm->dlm_locking_proto.pv_major == 1 &&
+	    dlm->dlm_locking_proto.pv_minor < 2)
+		return;
+
+	/*
+	 * Unlike DLM_EXIT_DOMAIN_MSG, DLM_BEGIN_EXIT_DOMAIN_MSG is purely
+	 * informational. Meaning if a node does not receive the message,
+	 * so be it.
+	 */
+	spin_lock(&dlm->spinlock);
+	while (1) {
+		node = find_next_bit(dlm->domain_map, O2NM_MAX_NODES, node + 1);
+		if (node >= O2NM_MAX_NODES)
+			break;
+		if (node == dlm->node_num)
+			continue;
+
+		spin_unlock(&dlm->spinlock);
+		dlm_send_one_domain_exit(dlm, DLM_BEGIN_EXIT_DOMAIN_MSG, node);
+		spin_lock(&dlm->spinlock);
+	}
+	spin_unlock(&dlm->spinlock);
+}
 
 static void dlm_leave_domain(struct dlm_ctxt *dlm)
 {
@@ -602,7 +650,8 @@ static void dlm_leave_domain(struct dlm_ctxt *dlm)
 
 		clear_node = 1;
 
-		status = dlm_send_one_domain_exit(dlm, node);
+		status = dlm_send_one_domain_exit(dlm, DLM_EXIT_DOMAIN_MSG,
+						  node);
 		if (status < 0 &&
 		    status != -ENOPROTOOPT &&
 		    status != -ENOTCONN) {
@@ -677,6 +726,7 @@ void dlm_unregister_domain(struct dlm_ctxt *dlm)
 
 	if (leave) {
 		mlog(0, "shutting down domain %s\n", dlm->name);
+		dlm_begin_exit_domain(dlm);
 
 		/* We changed dlm state, notify the thread */
 		dlm_kick_thread(dlm, NULL);
@@ -697,6 +747,7 @@ void dlm_unregister_domain(struct dlm_ctxt *dlm)
 
 		dlm_mark_domain_leaving(dlm);
 		dlm_leave_domain(dlm);
+		printk(KERN_NOTICE "o2dlm: Leaving domain %s\n", dlm->name);
 		dlm_force_free_mles(dlm);
 		dlm_complete_dlm_shutdown(dlm);
 	}
@@ -755,7 +806,7 @@ static void dlm_query_join_packet_to_wire(struct dlm_query_join_packet *packet,
 	union dlm_query_join_response response;
 
 	response.packet = *packet;
-	*wire = cpu_to_be32(response.intval);
+	*wire = be32_to_cpu(response.intval);
 }
 
 static void dlm_query_join_wire_to_packet(u32 wire,
@@ -908,10 +959,19 @@ static int dlm_assert_joined_handler(struct o2net_msg *msg, u32 len, void *data,
 		 * domain. Set him in the map and clean up our
 		 * leftover join state. */
 		BUG_ON(dlm->joining_node != assert->node_idx);
+
+		if (dlm->reco.state & DLM_RECO_STATE_ACTIVE) {
+			mlog(0, "dlm recovery is ongoing, disallow join\n");
+			spin_unlock(&dlm->spinlock);
+			spin_unlock(&dlm_domain_lock);
+			return -EAGAIN;
+		}
+
 		set_bit(assert->node_idx, dlm->domain_map);
+		clear_bit(assert->node_idx, dlm->exit_domain_map);
 		__dlm_set_joining_node(dlm, DLM_LOCK_RES_OWNER_UNKNOWN);
 
-		printk(KERN_NOTICE "o2dlm: Node %u joins domain %s\n",
+		printk(KERN_NOTICE "o2dlm: Node %u joins domain %s ",
 		       assert->node_idx, dlm->name);
 		__dlm_print_nodes(dlm);
 
@@ -926,9 +986,10 @@ static int dlm_assert_joined_handler(struct o2net_msg *msg, u32 len, void *data,
 }
 
 static int dlm_match_regions(struct dlm_ctxt *dlm,
-			     struct dlm_query_region *qr)
+			     struct dlm_query_region *qr,
+			     char *local, int locallen)
 {
-	char *local = NULL, *remote = qr->qr_regions;
+	char *remote = qr->qr_regions;
 	char *l, *r;
 	int localnr, i, j, foundit;
 	int status = 0;
@@ -957,13 +1018,8 @@ static int dlm_match_regions(struct dlm_ctxt *dlm,
 		r += O2HB_MAX_REGION_NAME_LEN;
 	}
 
-	local = kmalloc(sizeof(qr->qr_regions), GFP_ATOMIC);
-	if (!local) {
-		status = -ENOMEM;
-		goto bail;
-	}
-
-	localnr = o2hb_get_all_regions(local, O2NM_MAX_REGIONS);
+	localnr = min(O2NM_MAX_REGIONS, locallen/O2HB_MAX_REGION_NAME_LEN);
+	localnr = o2hb_get_all_regions(local, (u8)localnr);
 
 	/* compare local regions with remote */
 	l = local;
@@ -1012,8 +1068,6 @@ static int dlm_match_regions(struct dlm_ctxt *dlm,
 	}
 
 bail:
-	kfree(local);
-
 	return status;
 }
 
@@ -1075,14 +1129,19 @@ static int dlm_query_region_handler(struct o2net_msg *msg, u32 len,
 {
 	struct dlm_query_region *qr;
 	struct dlm_ctxt *dlm = NULL;
+	char *local = NULL;
 	int status = 0;
-	int locked = 0;
 
 	qr = (struct dlm_query_region *) msg->buf;
 
 	mlog(0, "Node %u queries hb regions on domain %s\n", qr->qr_node,
 	     qr->qr_domain);
 
+	/* buffer used in dlm_mast_regions() */
+	local = kmalloc(sizeof(qr->qr_regions), GFP_KERNEL);
+	if (!local)
+		return -ENOMEM;
+
 	status = -EINVAL;
 
 	spin_lock(&dlm_domain_lock);
@@ -1090,16 +1149,15 @@ static int dlm_query_region_handler(struct o2net_msg *msg, u32 len,
 	if (!dlm) {
 		mlog(ML_ERROR, "Node %d queried hb regions on domain %s "
 		     "before join domain\n", qr->qr_node, qr->qr_domain);
-		goto bail;
+		goto out_domain_lock;
 	}
 
 	spin_lock(&dlm->spinlock);
-	locked = 1;
 	if (dlm->joining_node != qr->qr_node) {
 		mlog(ML_ERROR, "Node %d queried hb regions on domain %s "
 		     "but joining node is %d\n", qr->qr_node, qr->qr_domain,
 		     dlm->joining_node);
-		goto bail;
+		goto out_dlm_lock;
 	}
 
 	/* Support for global heartbeat was added in 1.1 */
@@ -1109,16 +1167,19 @@ static int dlm_query_region_handler(struct o2net_msg *msg, u32 len,
 		     "but active dlm protocol is %d.%d\n", qr->qr_node,
 		     qr->qr_domain, dlm->dlm_locking_proto.pv_major,
 		     dlm->dlm_locking_proto.pv_minor);
-		goto bail;
+		goto out_dlm_lock;
 	}
 
-	status = dlm_match_regions(dlm, qr);
+	status = dlm_match_regions(dlm, qr, local, sizeof(qr->qr_regions));
 
-bail:
-	if (locked)
-		spin_unlock(&dlm->spinlock);
+out_dlm_lock:
+	spin_unlock(&dlm->spinlock);
+
+out_domain_lock:
 	spin_unlock(&dlm_domain_lock);
 
+	kfree(local);
+
 	return status;
 }
 
@@ -1464,6 +1525,7 @@ static int dlm_send_one_join_assert(struct dlm_ctxt *dlm,
 				    unsigned int node)
 {
 	int status;
+	int ret;
 	struct dlm_assert_joined assert_msg;
 
 	mlog(0, "Sending join assert to node %u\n", node);
@@ -1475,11 +1537,13 @@ static int dlm_send_one_join_assert(struct dlm_ctxt *dlm,
 
 	status = o2net_send_message(DLM_ASSERT_JOINED_MSG, DLM_MOD_KEY,
 				    &assert_msg, sizeof(assert_msg), node,
-				    NULL);
+				    &ret);
 	if (status < 0)
 		mlog(ML_ERROR, "Error %d when sending message %u (key 0x%x) to "
 		     "node %u\n", status, DLM_ASSERT_JOINED_MSG, DLM_MOD_KEY,
 		     node);
+	else
+		status = ret;
 
 	return status;
 }
@@ -1553,7 +1617,7 @@ static int dlm_try_to_join_domain(struct dlm_ctxt *dlm)
 	struct domain_join_ctxt *ctxt;
 	enum dlm_query_join_response_code response = JOIN_DISALLOW;
 
-	mlog_entry("%p", dlm);
+	mlog(0, "%p", dlm);
 
 	ctxt = kzalloc(sizeof(*ctxt), GFP_KERNEL);
 	if (!ctxt) {
@@ -1610,7 +1674,8 @@ static int dlm_try_to_join_domain(struct dlm_ctxt *dlm)
 	spin_unlock(&dlm->spinlock);
 
 	/* Support for global heartbeat and node info was added in 1.1 */
-	if (dlm_protocol.pv_major > 1 || dlm_protocol.pv_minor > 0) {
+	if (dlm->dlm_locking_proto.pv_major > 1 ||
+	    dlm->dlm_locking_proto.pv_minor > 0) {
 		status = dlm_send_nodeinfo(dlm, ctxt->yes_resp_map);
 		if (status) {
 			mlog_errno(status);
@@ -1637,8 +1702,10 @@ static int dlm_try_to_join_domain(struct dlm_ctxt *dlm)
 bail:
 	spin_lock(&dlm->spinlock);
 	__dlm_set_joining_node(dlm, DLM_LOCK_RES_OWNER_UNKNOWN);
-	if (!status)
+	if (!status) {
+		printk(KERN_NOTICE "o2dlm: Joining domain %s ", dlm->name);
 		__dlm_print_nodes(dlm);
+	}
 	spin_unlock(&dlm->spinlock);
 
 	if (ctxt) {
@@ -1788,6 +1855,13 @@ static int dlm_register_domain_handlers(struct dlm_ctxt *dlm)
 	if (status)
 		goto bail;
 
+	status = o2net_register_handler(DLM_BEGIN_EXIT_DOMAIN_MSG, dlm->key,
+					sizeof(struct dlm_exit_domain),
+					dlm_begin_exit_domain_handler,
+					dlm, NULL, &dlm->dlm_domain_handlers);
+	if (status)
+		goto bail;
+
 bail:
 	if (status)
 		dlm_unregister_domain_handlers(dlm);
@@ -1811,19 +1885,19 @@ static int dlm_join_domain(struct dlm_ctxt *dlm)
 		goto bail;
 	}
 
-	status = dlm_debug_init(dlm);
+	status = dlm_launch_thread(dlm);
 	if (status < 0) {
 		mlog_errno(status);
 		goto bail;
 	}
 
-	status = dlm_launch_thread(dlm);
+	status = dlm_launch_recovery_thread(dlm);
 	if (status < 0) {
 		mlog_errno(status);
 		goto bail;
 	}
 
-	status = dlm_launch_recovery_thread(dlm);
+	status = dlm_debug_init(dlm);
 	if (status < 0) {
 		mlog_errno(status);
 		goto bail;
@@ -1960,7 +2034,6 @@ static struct dlm_ctxt *dlm_alloc_ctxt(const char *domain,
 	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);
@@ -2060,13 +2133,6 @@ struct dlm_ctxt * dlm_register_domain(const char *domain,
 		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:
@@ -2227,13 +2293,10 @@ 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);
-
+	list_for_each_entry(cb, &dlm->dlm_eviction_callbacks, ec_item) {
 		cb->ec_func(node_num, cb->ec_data);
 	}
 	up_read(&dlm_callback_sem);
@@ -2270,8 +2333,6 @@ 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");
@@ -2321,6 +2382,7 @@ static void __exit dlm_exit (void)
 
 MODULE_AUTHOR("Oracle");
 MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("OCFS2 Distributed Lock Management");
 
 module_init(dlm_init);
 module_exit(dlm_exit);