1 files changed, 432 insertions, 208 deletions

diff --git a/fs/ocfs2/cluster/heartbeat.c b/fs/ocfs2/cluster/heartbeat.c
index 52c7557f3e2..73039295d0d 100644
--- a/fs/ocfs2/cluster/heartbeat.c
+++ b/fs/ocfs2/cluster/heartbeat.c
@@ -35,6 +35,7 @@
 #include <linux/time.h>
 #include <linux/debugfs.h>
 #include <linux/slab.h>
+#include <linux/bitmap.h>
 
 #include "heartbeat.h"
 #include "tcp.h"
@@ -82,6 +83,7 @@ static unsigned long o2hb_failed_region_bitmap[BITS_TO_LONGS(O2NM_MAX_REGIONS)];
 #define O2HB_DB_TYPE_REGION_LIVENODES	4
 #define O2HB_DB_TYPE_REGION_NUMBER	5
 #define O2HB_DB_TYPE_REGION_ELAPSED_TIME	6
+#define O2HB_DB_TYPE_REGION_PINNED	7
 struct o2hb_debug_buf {
 	int db_type;
 	int db_size;
@@ -101,6 +103,7 @@ static struct o2hb_debug_buf *o2hb_db_failedregions;
 #define O2HB_DEBUG_FAILEDREGIONS	"failed_regions"
 #define O2HB_DEBUG_REGION_NUMBER	"num"
 #define O2HB_DEBUG_REGION_ELAPSED_TIME	"elapsed_time_in_ms"
+#define O2HB_DEBUG_REGION_PINNED	"pinned"
 
 static struct dentry *o2hb_debug_dir;
 static struct dentry *o2hb_debug_livenodes;
@@ -132,6 +135,33 @@ char *o2hb_heartbeat_mode_desc[O2HB_HEARTBEAT_NUM_MODES] = {
 unsigned int o2hb_dead_threshold = O2HB_DEFAULT_DEAD_THRESHOLD;
 unsigned int o2hb_heartbeat_mode = O2HB_HEARTBEAT_LOCAL;
 
+/*
+ * o2hb_dependent_users tracks the number of registered callbacks that depend
+ * on heartbeat. o2net and o2dlm are two entities that register this callback.
+ * However only o2dlm depends on the heartbeat. It does not want the heartbeat
+ * to stop while a dlm domain is still active.
+ */
+unsigned int o2hb_dependent_users;
+
+/*
+ * In global heartbeat mode, all regions are pinned if there are one or more
+ * dependent users and the quorum region count is <= O2HB_PIN_CUT_OFF. All
+ * regions are unpinned if the region count exceeds the cut off or the number
+ * of dependent users falls to zero.
+ */
+#define O2HB_PIN_CUT_OFF		3
+
+/*
+ * In local heartbeat mode, we assume the dlm domain name to be the same as
+ * region uuid. This is true for domains created for the file system but not
+ * necessarily true for userdlm domains. This is a known limitation.
+ *
+ * In global heartbeat mode, we pin/unpin all o2hb regions. This solution
+ * works for both file system and userdlm domains.
+ */
+static int o2hb_region_pin(const char *region_uuid);
+static void o2hb_region_unpin(const char *region_uuid);
+
 /* Only sets a new threshold if there are no active regions.
  *
  * No locking or otherwise interesting code is required for reading
@@ -147,7 +177,7 @@ static void o2hb_dead_threshold_set(unsigned int threshold)
 	}
 }
 
-static int o2hb_global_hearbeat_mode_set(unsigned int hb_mode)
+static int o2hb_global_heartbeat_mode_set(unsigned int hb_mode)
 {
 	int ret = -1;
 
@@ -186,7 +216,10 @@ struct o2hb_region {
 	struct config_item	hr_item;
 
 	struct list_head	hr_all_item;
-	unsigned		hr_unclean_stop:1;
+	unsigned		hr_unclean_stop:1,
+				hr_aborted_start:1,
+				hr_item_pinned:1,
+				hr_item_dropped:1;
 
 	/* protected by the hr_callback_sem */
 	struct task_struct 	*hr_task;
@@ -212,15 +245,21 @@ struct o2hb_region {
 	struct dentry		*hr_debug_livenodes;
 	struct dentry		*hr_debug_regnum;
 	struct dentry		*hr_debug_elapsed_time;
+	struct dentry		*hr_debug_pinned;
 	struct o2hb_debug_buf	*hr_db_livenodes;
 	struct o2hb_debug_buf	*hr_db_regnum;
 	struct o2hb_debug_buf	*hr_db_elapsed_time;
+	struct o2hb_debug_buf	*hr_db_pinned;
 
 	/* let the person setting up hb wait for it to return until it
 	 * has reached a 'steady' state.  This will be fixed when we have
 	 * a more complete api that doesn't lead to this sort of fragility. */
 	atomic_t		hr_steady_iterations;
 
+	/* terminate o2hb thread if it does not reach steady state
+	 * (hr_steady_iterations == 0) within hr_unsteady_iterations */
+	atomic_t		hr_unsteady_iterations;
+
 	char			hr_dev_name[BDEVNAME_SIZE];
 
 	unsigned int		hr_timeout_ms;
@@ -244,15 +283,6 @@ struct o2hb_bio_wait_ctxt {
 	int               wc_error;
 };
 
-static int o2hb_pop_count(void *map, int count)
-{
-	int i = -1, pop = 0;
-
-	while ((i = find_next_bit(map, count, i + 1)) < count)
-		pop++;
-	return pop;
-}
-
 static void o2hb_write_timeout(struct work_struct *work)
 {
 	int failed, quorum;
@@ -269,9 +299,9 @@ static void o2hb_write_timeout(struct work_struct *work)
 		spin_lock_irqsave(&o2hb_live_lock, flags);
 		if (test_bit(reg->hr_region_num, o2hb_quorum_region_bitmap))
 			set_bit(reg->hr_region_num, o2hb_failed_region_bitmap);
-		failed = o2hb_pop_count(&o2hb_failed_region_bitmap,
+		failed = bitmap_weight(o2hb_failed_region_bitmap,
 					O2NM_MAX_REGIONS);
-		quorum = o2hb_pop_count(&o2hb_quorum_region_bitmap,
+		quorum = bitmap_weight(o2hb_quorum_region_bitmap,
 					O2NM_MAX_REGIONS);
 		spin_unlock_irqrestore(&o2hb_live_lock, flags);
 
@@ -291,6 +321,10 @@ static void o2hb_write_timeout(struct work_struct *work)
 
 static void o2hb_arm_write_timeout(struct o2hb_region *reg)
 {
+	/* Arm writeout only after thread reaches steady state */
+	if (atomic_read(&reg->hr_steady_iterations) != 0)
+		return;
+
 	mlog(ML_HEARTBEAT, "Queue write timeout for %u ms\n",
 	     O2HB_MAX_WRITE_TIMEOUT_MS);
 
@@ -307,8 +341,7 @@ static void o2hb_arm_write_timeout(struct o2hb_region *reg)
 
 static void o2hb_disarm_write_timeout(struct o2hb_region *reg)
 {
-	cancel_delayed_work(&reg->hr_write_timeout_work);
-	flush_scheduled_work();
+	cancel_delayed_work_sync(&reg->hr_write_timeout_work);
 }
 
 static inline void o2hb_bio_wait_init(struct o2hb_bio_wait_ctxt *wc)
@@ -335,11 +368,7 @@ static inline void o2hb_bio_wait_dec(struct o2hb_bio_wait_ctxt *wc,
 static void o2hb_wait_on_io(struct o2hb_region *reg,
 			    struct o2hb_bio_wait_ctxt *wc)
 {
-	struct address_space *mapping = reg->hr_bdev->bd_inode->i_mapping;
-
-	blk_run_address_space(mapping);
 	o2hb_bio_wait_dec(wc, 1);
-
 	wait_for_completion(&wc->wc_io_complete);
 }
 
@@ -384,7 +413,7 @@ static struct bio *o2hb_setup_one_bio(struct o2hb_region *reg,
 	}
 
 	/* Must put everything in 512 byte sectors for the bio... */
-	bio->bi_sector = (reg->hr_start_block + cs) << (bits - 9);
+	bio->bi_iter.bi_sector = (reg->hr_start_block + cs) << (bits - 9);
 	bio->bi_bdev = reg->hr_bdev;
 	bio->bi_private = wc;
 	bio->bi_end_io = o2hb_bio_end_io;
@@ -463,7 +492,7 @@ static int o2hb_issue_node_write(struct o2hb_region *reg,
 	}
 
 	atomic_inc(&write_wc->wc_num_reqs);
-	submit_bio(WRITE, bio);
+	submit_bio(WRITE_SYNC, bio);
 
 	status = 0;
 bail:
@@ -509,27 +538,50 @@ static int o2hb_verify_crc(struct o2hb_region *reg,
 	return read == computed;
 }
 
-/* We want to make sure that nobody is heartbeating on top of us --
- * this will help detect an invalid configuration. */
-static int o2hb_check_last_timestamp(struct o2hb_region *reg)
+/*
+ * Compare the slot data with what we wrote in the last iteration.
+ * If the match fails, print an appropriate error message. This is to
+ * detect errors like... another node hearting on the same slot,
+ * flaky device that is losing writes, etc.
+ * Returns 1 if check succeeds, 0 otherwise.
+ */
+static int o2hb_check_own_slot(struct o2hb_region *reg)
 {
-	int node_num, ret;
 	struct o2hb_disk_slot *slot;
 	struct o2hb_disk_heartbeat_block *hb_block;
+	char *errstr;
 
-	node_num = o2nm_this_node();
-
-	ret = 1;
-	slot = &reg->hr_slots[node_num];
+	slot = &reg->hr_slots[o2nm_this_node()];
 	/* Don't check on our 1st timestamp */
-	if (slot->ds_last_time) {
-		hb_block = slot->ds_raw_block;
+	if (!slot->ds_last_time)
+		return 0;
 
-		if (le64_to_cpu(hb_block->hb_seq) != slot->ds_last_time)
-			ret = 0;
-	}
+	hb_block = slot->ds_raw_block;
+	if (le64_to_cpu(hb_block->hb_seq) == slot->ds_last_time &&
+	    le64_to_cpu(hb_block->hb_generation) == slot->ds_last_generation &&
+	    hb_block->hb_node == slot->ds_node_num)
+		return 1;
+
+#define ERRSTR1		"Another node is heartbeating on device"
+#define ERRSTR2		"Heartbeat generation mismatch on device"
+#define ERRSTR3		"Heartbeat sequence mismatch on device"
+
+	if (hb_block->hb_node != slot->ds_node_num)
+		errstr = ERRSTR1;
+	else if (le64_to_cpu(hb_block->hb_generation) !=
+		 slot->ds_last_generation)
+		errstr = ERRSTR2;
+	else
+		errstr = ERRSTR3;
 
-	return ret;
+	mlog(ML_ERROR, "%s (%s): expected(%u:0x%llx, 0x%llx), "
+	     "ondisk(%u:0x%llx, 0x%llx)\n", errstr, reg->hr_dev_name,
+	     slot->ds_node_num, (unsigned long long)slot->ds_last_generation,
+	     (unsigned long long)slot->ds_last_time, hb_block->hb_node,
+	     (unsigned long long)le64_to_cpu(hb_block->hb_generation),
+	     (unsigned long long)le64_to_cpu(hb_block->hb_seq));
+
+	return 0;
 }
 
 static inline void o2hb_prepare_block(struct o2hb_region *reg,
@@ -568,11 +620,9 @@ static void o2hb_fire_callbacks(struct o2hb_callback *hbcall,
 				struct o2nm_node *node,
 				int idx)
 {
-	struct list_head *iter;
 	struct o2hb_callback_func *f;
 
-	list_for_each(iter, &hbcall->list) {
-		f = list_entry(iter, struct o2hb_callback_func, hc_item);
+	list_for_each_entry(f, &hbcall->list, hc_item) {
 		mlog(ML_HEARTBEAT, "calling funcs %p\n", f);
 		(f->hc_func)(node, idx, f->hc_data);
 	}
@@ -581,16 +631,9 @@ static void o2hb_fire_callbacks(struct o2hb_callback *hbcall,
 /* Will run the list in order until we process the passed event */
 static void o2hb_run_event_list(struct o2hb_node_event *queued_event)
 {
-	int empty;
 	struct o2hb_callback *hbcall;
 	struct o2hb_node_event *event;
 
-	spin_lock(&o2hb_live_lock);
-	empty = list_empty(&queued_event->hn_item);
-	spin_unlock(&o2hb_live_lock);
-	if (empty)
-		return;
-
 	/* Holding callback sem assures we don't alter the callback
 	 * lists when doing this, and serializes ourselves with other
 	 * processes wanting callbacks. */
@@ -649,6 +692,7 @@ static void o2hb_shutdown_slot(struct o2hb_disk_slot *slot)
 	struct o2hb_node_event event =
 		{ .hn_item = LIST_HEAD_INIT(event.hn_item), };
 	struct o2nm_node *node;
+	int queued = 0;
 
 	node = o2nm_get_node_by_num(slot->ds_node_num);
 	if (!node)
@@ -666,26 +710,35 @@ static void o2hb_shutdown_slot(struct o2hb_disk_slot *slot)
 
 			o2hb_queue_node_event(&event, O2HB_NODE_DOWN_CB, node,
 					      slot->ds_node_num);
+			queued = 1;
 		}
 	}
 	spin_unlock(&o2hb_live_lock);
 
-	o2hb_run_event_list(&event);
+	if (queued)
+		o2hb_run_event_list(&event);
 
 	o2nm_node_put(node);
 }
 
-static void o2hb_set_quorum_device(struct o2hb_region *reg,
-				   struct o2hb_disk_slot *slot)
+static void o2hb_set_quorum_device(struct o2hb_region *reg)
 {
-	assert_spin_locked(&o2hb_live_lock);
-
 	if (!o2hb_global_heartbeat_active())
 		return;
 
-	if (test_bit(reg->hr_region_num, o2hb_quorum_region_bitmap))
+	/* Prevent race with o2hb_heartbeat_group_drop_item() */
+	if (kthread_should_stop())
 		return;
 
+	/* Tag region as quorum only after thread reaches steady state */
+	if (atomic_read(&reg->hr_steady_iterations) != 0)
+		return;
+
+	spin_lock(&o2hb_live_lock);
+
+	if (test_bit(reg->hr_region_num, o2hb_quorum_region_bitmap))
+		goto unlock;
+
 	/*
 	 * A region can be added to the quorum only when it sees all
 	 * live nodes heartbeat on it. In other words, the region has been
@@ -693,15 +746,22 @@ static void o2hb_set_quorum_device(struct o2hb_region *reg,
 	 */
 	if (memcmp(reg->hr_live_node_bitmap, o2hb_live_node_bitmap,
 		   sizeof(o2hb_live_node_bitmap)))
-		return;
-
-	if (slot->ds_changed_samples < O2HB_LIVE_THRESHOLD)
-		return;
+		goto unlock;
 
-	printk(KERN_NOTICE "o2hb: Region %s is now a quorum device\n",
-	       config_item_name(&reg->hr_item));
+	printk(KERN_NOTICE "o2hb: Region %s (%s) is now a quorum device\n",
+	       config_item_name(&reg->hr_item), reg->hr_dev_name);
 
 	set_bit(reg->hr_region_num, o2hb_quorum_region_bitmap);
+
+	/*
+	 * If global heartbeat active, unpin all regions if the
+	 * region count > CUT_OFF
+	 */
+	if (bitmap_weight(o2hb_quorum_region_bitmap,
+			   O2NM_MAX_REGIONS) > O2HB_PIN_CUT_OFF)
+		o2hb_region_unpin(NULL);
+unlock:
+	spin_unlock(&o2hb_live_lock);
 }
 
 static int o2hb_check_slot(struct o2hb_region *reg,
@@ -716,6 +776,7 @@ static int o2hb_check_slot(struct o2hb_region *reg,
 	unsigned int dead_ms = o2hb_dead_threshold * O2HB_REGION_TIMEOUT_MS;
 	unsigned int slot_dead_ms;
 	int tmp;
+	int queued = 0;
 
 	memcpy(hb_block, slot->ds_raw_block, reg->hr_block_bytes);
 
@@ -809,6 +870,7 @@ fire_callbacks:
 					      slot->ds_node_num);
 
 			changed = 1;
+			queued = 1;
 		}
 
 		list_add_tail(&slot->ds_live_item,
@@ -860,6 +922,7 @@ fire_callbacks:
 					      node, slot->ds_node_num);
 
 			changed = 1;
+			queued = 1;
 		}
 
 		/* We don't clear this because the node is still
@@ -873,39 +936,25 @@ fire_callbacks:
 		slot->ds_equal_samples = 0;
 	}
 out:
-	o2hb_set_quorum_device(reg, slot);
-
 	spin_unlock(&o2hb_live_lock);
 
-	o2hb_run_event_list(&event);
+	if (queued)
+		o2hb_run_event_list(&event);
 
 	if (node)
 		o2nm_node_put(node);
 	return changed;
 }
 
-/* This could be faster if we just implmented a find_last_bit, but I
- * don't think the circumstances warrant it. */
-static int o2hb_highest_node(unsigned long *nodes,
-			     int numbits)
+static int o2hb_highest_node(unsigned long *nodes, int numbits)
 {
-	int highest, node;
-
-	highest = numbits;
-	node = -1;
-	while ((node = find_next_bit(nodes, numbits, node + 1)) != -1) {
-		if (node >= numbits)
-			break;
-
-		highest = node;
-	}
-
-	return highest;
+	return find_last_bit(nodes, numbits);
 }
 
 static int o2hb_do_disk_heartbeat(struct o2hb_region *reg)
 {
-	int i, ret, highest_node, change = 0;
+	int i, ret, highest_node;
+	int membership_change = 0, own_slot_ok = 0;
 	unsigned long configured_nodes[BITS_TO_LONGS(O2NM_MAX_NODES)];
 	unsigned long live_node_bitmap[BITS_TO_LONGS(O2NM_MAX_NODES)];
 	struct o2hb_bio_wait_ctxt write_wc;
@@ -914,7 +963,7 @@ static int o2hb_do_disk_heartbeat(struct o2hb_region *reg)
 				       sizeof(configured_nodes));
 	if (ret) {
 		mlog_errno(ret);
-		return ret;
+		goto bail;
 	}
 
 	/*
@@ -930,8 +979,9 @@ static int o2hb_do_disk_heartbeat(struct o2hb_region *reg)
 
 	highest_node = o2hb_highest_node(configured_nodes, O2NM_MAX_NODES);
 	if (highest_node >= O2NM_MAX_NODES) {
-		mlog(ML_NOTICE, "ocfs2_heartbeat: no configured nodes found!\n");
-		return -EINVAL;
+		mlog(ML_NOTICE, "o2hb: No configured nodes found!\n");
+		ret = -EINVAL;
+		goto bail;
 	}
 
 	/* No sense in reading the slots of nodes that don't exist
@@ -941,31 +991,27 @@ static int o2hb_do_disk_heartbeat(struct o2hb_region *reg)
 	ret = o2hb_read_slots(reg, highest_node + 1);
 	if (ret < 0) {
 		mlog_errno(ret);
-		return ret;
+		goto bail;
 	}
 
 	/* With an up to date view of the slots, we can check that no
 	 * other node has been improperly configured to heartbeat in
 	 * our slot. */
-	if (!o2hb_check_last_timestamp(reg))
-		mlog(ML_ERROR, "Device \"%s\": another node is heartbeating "
-		     "in our slot!\n", reg->hr_dev_name);
+	own_slot_ok = o2hb_check_own_slot(reg);
 
 	/* fill in the proper info for our next heartbeat */
 	o2hb_prepare_block(reg, reg->hr_generation);
 
-	/* And fire off the write. Note that we don't wait on this I/O
-	 * until later. */
 	ret = o2hb_issue_node_write(reg, &write_wc);
 	if (ret < 0) {
 		mlog_errno(ret);
-		return ret;
+		goto bail;
 	}
 
 	i = -1;
-	while((i = find_next_bit(configured_nodes, O2NM_MAX_NODES, i + 1)) < O2NM_MAX_NODES) {
-
-		change |= o2hb_check_slot(reg, &reg->hr_slots[i]);
+	while((i = find_next_bit(configured_nodes,
+				 O2NM_MAX_NODES, i + 1)) < O2NM_MAX_NODES) {
+		membership_change |= o2hb_check_slot(reg, &reg->hr_slots[i]);
 	}
 
 	/*
@@ -980,18 +1026,39 @@ static int o2hb_do_disk_heartbeat(struct o2hb_region *reg)
 		 * disk */
 		mlog(ML_ERROR, "Write error %d on device \"%s\"\n",
 		     write_wc.wc_error, reg->hr_dev_name);
-		return write_wc.wc_error;
+		ret = write_wc.wc_error;
+		goto bail;
 	}
 
-	o2hb_arm_write_timeout(reg);
+	/* Skip disarming the timeout if own slot has stale/bad data */
+	if (own_slot_ok) {
+		o2hb_set_quorum_device(reg);
+		o2hb_arm_write_timeout(reg);
+	}
 
+bail:
 	/* let the person who launched us know when things are steady */
-	if (!change && (atomic_read(&reg->hr_steady_iterations) != 0)) {
-		if (atomic_dec_and_test(&reg->hr_steady_iterations))
+	if (atomic_read(&reg->hr_steady_iterations) != 0) {
+		if (!ret && own_slot_ok && !membership_change) {
+			if (atomic_dec_and_test(&reg->hr_steady_iterations))
+				wake_up(&o2hb_steady_queue);
+		}
+	}
+
+	if (atomic_read(&reg->hr_steady_iterations) != 0) {
+		if (atomic_dec_and_test(&reg->hr_unsteady_iterations)) {
+			printk(KERN_NOTICE "o2hb: Unable to stabilize "
+			       "heartbeart on region %s (%s)\n",
+			       config_item_name(&reg->hr_item),
+			       reg->hr_dev_name);
+			atomic_set(&reg->hr_steady_iterations, 0);
+			reg->hr_aborted_start = 1;
 			wake_up(&o2hb_steady_queue);
+			ret = -EIO;
+		}
 	}
 
-	return 0;
+	return ret;
 }
 
 /* Subtract b from a, storing the result in a. a *must* have a larger
@@ -1040,9 +1107,13 @@ static int o2hb_thread(void *data)
 
 	mlog(ML_HEARTBEAT|ML_KTHREAD, "hb thread running\n");
 
-	set_user_nice(current, -20);
+	set_user_nice(current, MIN_NICE);
+
+	/* Pin node */
+	o2nm_depend_this_node();
 
-	while (!kthread_should_stop() && !reg->hr_unclean_stop) {
+	while (!kthread_should_stop() &&
+	       !reg->hr_unclean_stop && !reg->hr_aborted_start) {
 		/* We track the time spent inside
 		 * o2hb_do_disk_heartbeat so that we avoid more than
 		 * hr_timeout_ms between disk writes. On busy systems
@@ -1050,10 +1121,7 @@ static int o2hb_thread(void *data)
 		 * likely to time itself out. */
 		do_gettimeofday(&before_hb);
 
-		i = 0;
-		do {
-			ret = o2hb_do_disk_heartbeat(reg);
-		} while (ret && ++i < 2);
+		ret = o2hb_do_disk_heartbeat(reg);
 
 		do_gettimeofday(&after_hb);
 		elapsed_msec = o2hb_elapsed_msecs(&before_hb, &after_hb);
@@ -1064,7 +1132,8 @@ static int o2hb_thread(void *data)
 		     after_hb.tv_sec, (unsigned long) after_hb.tv_usec,
 		     elapsed_msec);
 
-		if (elapsed_msec < reg->hr_timeout_ms) {
+		if (!kthread_should_stop() &&
+		    elapsed_msec < reg->hr_timeout_ms) {
 			/* the kthread api has blocked signals for us so no
 			 * need to record the return value. */
 			msleep_interruptible(reg->hr_timeout_ms - elapsed_msec);
@@ -1081,17 +1150,20 @@ static int o2hb_thread(void *data)
 	 * to timeout on this region when we could just as easily
 	 * write a clear generation - thus indicating to them that
 	 * this node has left this region.
-	 *
-	 * XXX: Should we skip this on unclean_stop? */
-	o2hb_prepare_block(reg, 0);
-	ret = o2hb_issue_node_write(reg, &write_wc);
-	if (ret == 0) {
-		o2hb_wait_on_io(reg, &write_wc);
-	} else {
-		mlog_errno(ret);
+	 */
+	if (!reg->hr_unclean_stop && !reg->hr_aborted_start) {
+		o2hb_prepare_block(reg, 0);
+		ret = o2hb_issue_node_write(reg, &write_wc);
+		if (ret == 0)
+			o2hb_wait_on_io(reg, &write_wc);
+		else
+			mlog_errno(ret);
 	}
 
-	mlog(ML_HEARTBEAT|ML_KTHREAD, "hb thread exiting\n");
+	/* Unpin node */
+	o2nm_undepend_this_node();
+
+	mlog(ML_HEARTBEAT|ML_KTHREAD, "o2hb thread exiting\n");
 
 	return 0;
 }
@@ -1102,6 +1174,7 @@ static int o2hb_debug_open(struct inode *inode, struct file *file)
 	struct o2hb_debug_buf *db = inode->i_private;
 	struct o2hb_region *reg;
 	unsigned long map[BITS_TO_LONGS(O2NM_MAX_NODES)];
+	unsigned long lts;
 	char *buf = NULL;
 	int i = -1;
 	int out = 0;
@@ -1138,9 +1211,17 @@ static int o2hb_debug_open(struct inode *inode, struct file *file)
 
 	case O2HB_DB_TYPE_REGION_ELAPSED_TIME:
 		reg = (struct o2hb_region *)db->db_data;
+		lts = reg->hr_last_timeout_start;
+		/* If 0, it has never been set before */
+		if (lts)
+			lts = jiffies_to_msecs(jiffies - lts);
+		out += snprintf(buf + out, PAGE_SIZE - out, "%lu\n", lts);
+		goto done;
+
+	case O2HB_DB_TYPE_REGION_PINNED:
+		reg = (struct o2hb_region *)db->db_data;
 		out += snprintf(buf + out, PAGE_SIZE - out, "%u\n",
-				jiffies_to_msecs(jiffies -
-						 reg->hr_last_timeout_start));
+				!!reg->hr_item_pinned);
 		goto done;
 
 	default:
@@ -1316,6 +1397,8 @@ int o2hb_init(void)
 	memset(o2hb_quorum_region_bitmap, 0, sizeof(o2hb_quorum_region_bitmap));
 	memset(o2hb_failed_region_bitmap, 0, sizeof(o2hb_failed_region_bitmap));
 
+	o2hb_dependent_users = 0;
+
 	return o2hb_debug_init();
 }
 
@@ -1362,8 +1445,9 @@ static void o2hb_region_release(struct config_item *item)
 	struct page *page;
 	struct o2hb_region *reg = to_o2hb_region(item);
 
-	if (reg->hr_tmp_block)
-		kfree(reg->hr_tmp_block);
+	mlog(ML_HEARTBEAT, "hb region release (%s)\n", reg->hr_dev_name);
+
+	kfree(reg->hr_tmp_block);
 
 	if (reg->hr_slot_data) {
 		for (i = 0; i < reg->hr_num_pages; i++) {
@@ -1377,14 +1461,14 @@ static void o2hb_region_release(struct config_item *item)
 	if (reg->hr_bdev)
 		blkdev_put(reg->hr_bdev, FMODE_READ|FMODE_WRITE);
 
-	if (reg->hr_slots)
-		kfree(reg->hr_slots);
+	kfree(reg->hr_slots);
 
 	kfree(reg->hr_db_regnum);
 	kfree(reg->hr_db_livenodes);
 	debugfs_remove(reg->hr_debug_livenodes);
 	debugfs_remove(reg->hr_debug_regnum);
 	debugfs_remove(reg->hr_debug_elapsed_time);
+	debugfs_remove(reg->hr_debug_pinned);
 	debugfs_remove(reg->hr_debug_dir);
 
 	spin_lock(&o2hb_live_lock);
@@ -1603,8 +1687,6 @@ static int o2hb_populate_slot_data(struct o2hb_region *reg)
 	struct o2hb_disk_slot *slot;
 	struct o2hb_disk_heartbeat_block *hb_block;
 
-	mlog_entry_void();
-
 	ret = o2hb_read_slots(reg, reg->hr_blocks);
 	if (ret) {
 		mlog_errno(ret);
@@ -1626,7 +1708,6 @@ static int o2hb_populate_slot_data(struct o2hb_region *reg)
 	}
 
 out:
-	mlog_exit(ret);
 	return ret;
 }
 
@@ -1639,9 +1720,10 @@ static ssize_t o2hb_region_dev_write(struct o2hb_region *reg,
 	long fd;
 	int sectsize;
 	char *p = (char *)page;
-	struct file *filp = NULL;
-	struct inode *inode = NULL;
+	struct fd f;
+	struct inode *inode;
 	ssize_t ret = -EINVAL;
+	int live_threshold;
 
 	if (reg->hr_bdev)
 		goto out;
@@ -1658,26 +1740,26 @@ static ssize_t o2hb_region_dev_write(struct o2hb_region *reg,
 	if (fd < 0 || fd >= INT_MAX)
 		goto out;
 
-	filp = fget(fd);
-	if (filp == NULL)
+	f = fdget(fd);
+	if (f.file == NULL)
 		goto out;
 
 	if (reg->hr_blocks == 0 || reg->hr_start_block == 0 ||
 	    reg->hr_block_bytes == 0)
-		goto out;
+		goto out2;
 
-	inode = igrab(filp->f_mapping->host);
+	inode = igrab(f.file->f_mapping->host);
 	if (inode == NULL)
-		goto out;
+		goto out2;
 
 	if (!S_ISBLK(inode->i_mode))
-		goto out;
+		goto out3;
 
-	reg->hr_bdev = I_BDEV(filp->f_mapping->host);
-	ret = blkdev_get(reg->hr_bdev, FMODE_WRITE | FMODE_READ);
+	reg->hr_bdev = I_BDEV(f.file->f_mapping->host);
+	ret = blkdev_get(reg->hr_bdev, FMODE_WRITE | FMODE_READ, NULL);
 	if (ret) {
 		reg->hr_bdev = NULL;
-		goto out;
+		goto out3;
 	}
 	inode = NULL;
 
@@ -1689,7 +1771,7 @@ static ssize_t o2hb_region_dev_write(struct o2hb_region *reg,
 		     "blocksize %u incorrect for device, expected %d",
 		     reg->hr_block_bytes, sectsize);
 		ret = -EINVAL;
-		goto out;
+		goto out3;
 	}
 
 	o2hb_init_region_params(reg);
@@ -1703,13 +1785,13 @@ static ssize_t o2hb_region_dev_write(struct o2hb_region *reg,
 	ret = o2hb_map_slot_data(reg);
 	if (ret) {
 		mlog_errno(ret);
-		goto out;
+		goto out3;
 	}
 
 	ret = o2hb_populate_slot_data(reg);
 	if (ret) {
 		mlog_errno(ret);
-		goto out;
+		goto out3;
 	}
 
 	INIT_DELAYED_WORK(&reg->hr_write_timeout_work, o2hb_write_timeout);
@@ -1718,15 +1800,28 @@ static ssize_t o2hb_region_dev_write(struct o2hb_region *reg,
 	 * A node is considered live after it has beat LIVE_THRESHOLD
 	 * times.  We're not steady until we've given them a chance
 	 * _after_ our first read.
+	 * The default threshold is bare minimum so as to limit the delay
+	 * during mounts. For global heartbeat, the threshold doubled for the
+	 * first region.
 	 */
-	atomic_set(&reg->hr_steady_iterations, O2HB_LIVE_THRESHOLD + 1);
+	live_threshold = O2HB_LIVE_THRESHOLD;
+	if (o2hb_global_heartbeat_active()) {
+		spin_lock(&o2hb_live_lock);
+		if (bitmap_weight(o2hb_region_bitmap, O2NM_MAX_REGIONS) == 1)
+			live_threshold <<= 1;
+		spin_unlock(&o2hb_live_lock);
+	}
+	++live_threshold;
+	atomic_set(&reg->hr_steady_iterations, live_threshold);
+	/* unsteady_iterations is double the steady_iterations */
+	atomic_set(&reg->hr_unsteady_iterations, (live_threshold << 1));
 
 	hb_task = kthread_run(o2hb_thread, reg, "o2hb-%s",
 			      reg->hr_item.ci_name);
 	if (IS_ERR(hb_task)) {
 		ret = PTR_ERR(hb_task);
 		mlog_errno(ret);
-		goto out;
+		goto out3;
 	}
 
 	spin_lock(&o2hb_live_lock);
@@ -1736,15 +1831,13 @@ static ssize_t o2hb_region_dev_write(struct o2hb_region *reg,
 	ret = wait_event_interruptible(o2hb_steady_queue,
 				atomic_read(&reg->hr_steady_iterations) == 0);
 	if (ret) {
-		/* We got interrupted (hello ptrace!).  Clean up */
-		spin_lock(&o2hb_live_lock);
-		hb_task = reg->hr_task;
-		reg->hr_task = NULL;
-		spin_unlock(&o2hb_live_lock);
+		atomic_set(&reg->hr_steady_iterations, 0);
+		reg->hr_aborted_start = 1;
+	}
 
-		if (hb_task)
-			kthread_stop(hb_task);
-		goto out;
+	if (reg->hr_aborted_start) {
+		ret = -EIO;
+		goto out3;
 	}
 
 	/* Ok, we were woken.  Make sure it wasn't by drop_item() */
@@ -1760,14 +1853,14 @@ static ssize_t o2hb_region_dev_write(struct o2hb_region *reg,
 		ret = -EIO;
 
 	if (hb_task && o2hb_global_heartbeat_active())
-		printk(KERN_NOTICE "o2hb: Heartbeat started on region %s\n",
-		       config_item_name(&reg->hr_item));
+		printk(KERN_NOTICE "o2hb: Heartbeat started on region %s (%s)\n",
+		       config_item_name(&reg->hr_item), reg->hr_dev_name);
 
+out3:
+	iput(inode);
+out2:
+	fdput(f);
 out:
-	if (filp)
-		fput(filp);
-	if (inode)
-		iput(inode);
 	if (ret < 0) {
 		if (reg->hr_bdev) {
 			blkdev_put(reg->hr_bdev, FMODE_READ|FMODE_WRITE);
@@ -1949,6 +2042,18 @@ static int o2hb_debug_region_init(struct o2hb_region *reg, struct dentry *dir)
 		goto bail;
 	}
 
+	reg->hr_debug_pinned =
+			o2hb_debug_create(O2HB_DEBUG_REGION_PINNED,
+					  reg->hr_debug_dir,
+					  &(reg->hr_db_pinned),
+					  sizeof(*(reg->hr_db_pinned)),
+					  O2HB_DB_TYPE_REGION_PINNED,
+					  0, 0, reg);
+	if (!reg->hr_debug_pinned) {
+		mlog_errno(ret);
+		goto bail;
+	}
+
 	ret = 0;
 bail:
 	return ret;
@@ -1964,8 +2069,10 @@ static struct config_item *o2hb_heartbeat_group_make_item(struct config_group *g
 	if (reg == NULL)
 		return ERR_PTR(-ENOMEM);
 
-	if (strlen(name) > O2HB_MAX_REGION_NAME_LEN)
-		return ERR_PTR(-ENAMETOOLONG);
+	if (strlen(name) > O2HB_MAX_REGION_NAME_LEN) {
+		ret = -ENAMETOOLONG;
+		goto free;
+	}
 
 	spin_lock(&o2hb_live_lock);
 	reg->hr_region_num = 0;
@@ -1974,7 +2081,8 @@ static struct config_item *o2hb_heartbeat_group_make_item(struct config_group *g
 							 O2NM_MAX_REGIONS);
 		if (reg->hr_region_num >= O2NM_MAX_REGIONS) {
 			spin_unlock(&o2hb_live_lock);
-			return ERR_PTR(-EFBIG);
+			ret = -EFBIG;
+			goto free;
 		}
 		set_bit(reg->hr_region_num, o2hb_region_bitmap);
 	}
@@ -1986,10 +2094,13 @@ static struct config_item *o2hb_heartbeat_group_make_item(struct config_group *g
 	ret = o2hb_debug_region_init(reg, o2hb_debug_dir);
 	if (ret) {
 		config_item_put(&reg->hr_item);
-		return ERR_PTR(ret);
+		goto free;
 	}
 
 	return &reg->hr_item;
+free:
+	kfree(reg);
+	return ERR_PTR(ret);
 }
 
 static void o2hb_heartbeat_group_drop_item(struct config_group *group,
@@ -1997,33 +2108,62 @@ static void o2hb_heartbeat_group_drop_item(struct config_group *group,
 {
 	struct task_struct *hb_task;
 	struct o2hb_region *reg = to_o2hb_region(item);
+	int quorum_region = 0;
 
 	/* stop the thread when the user removes the region dir */
 	spin_lock(&o2hb_live_lock);
-	if (o2hb_global_heartbeat_active()) {
-		clear_bit(reg->hr_region_num, o2hb_region_bitmap);
-		clear_bit(reg->hr_region_num, o2hb_live_region_bitmap);
-	}
 	hb_task = reg->hr_task;
 	reg->hr_task = NULL;
+	reg->hr_item_dropped = 1;
 	spin_unlock(&o2hb_live_lock);
 
 	if (hb_task)
 		kthread_stop(hb_task);
 
+	if (o2hb_global_heartbeat_active()) {
+		spin_lock(&o2hb_live_lock);
+		clear_bit(reg->hr_region_num, o2hb_region_bitmap);
+		clear_bit(reg->hr_region_num, o2hb_live_region_bitmap);
+		if (test_bit(reg->hr_region_num, o2hb_quorum_region_bitmap))
+			quorum_region = 1;
+		clear_bit(reg->hr_region_num, o2hb_quorum_region_bitmap);
+		spin_unlock(&o2hb_live_lock);
+		printk(KERN_NOTICE "o2hb: Heartbeat %s on region %s (%s)\n",
+		       ((atomic_read(&reg->hr_steady_iterations) == 0) ?
+			"stopped" : "start aborted"), config_item_name(item),
+		       reg->hr_dev_name);
+	}
+
 	/*
 	 * If we're racing a dev_write(), we need to wake them.  They will
 	 * check reg->hr_task
 	 */
 	if (atomic_read(&reg->hr_steady_iterations) != 0) {
+		reg->hr_aborted_start = 1;
 		atomic_set(&reg->hr_steady_iterations, 0);
 		wake_up(&o2hb_steady_queue);
 	}
 
-	if (o2hb_global_heartbeat_active())
-		printk(KERN_NOTICE "o2hb: Heartbeat stopped on region %s\n",
-		       config_item_name(&reg->hr_item));
 	config_item_put(item);
+
+	if (!o2hb_global_heartbeat_active() || !quorum_region)
+		return;
+
+	/*
+	 * If global heartbeat active and there are dependent users,
+	 * pin all regions if quorum region count <= CUT_OFF
+	 */
+	spin_lock(&o2hb_live_lock);
+
+	if (!o2hb_dependent_users)
+		goto unlock;
+
+	if (bitmap_weight(o2hb_quorum_region_bitmap,
+			   O2NM_MAX_REGIONS) <= O2HB_PIN_CUT_OFF)
+		o2hb_region_pin(NULL);
+
+unlock:
+	spin_unlock(&o2hb_live_lock);
 }
 
 struct o2hb_heartbeat_group_attribute {
@@ -2107,7 +2247,7 @@ ssize_t o2hb_heartbeat_group_mode_store(struct o2hb_heartbeat_group *group,
 		if (strnicmp(page, o2hb_heartbeat_mode_desc[i], len))
 			continue;
 
-		ret = o2hb_global_hearbeat_mode_set(i);
+		ret = o2hb_global_heartbeat_mode_set(i);
 		if (!ret)
 			printk(KERN_NOTICE "o2hb: Heartbeat mode set to %s\n",
 			       o2hb_heartbeat_mode_desc[i]);
@@ -2140,7 +2280,7 @@ static struct configfs_attribute *o2hb_heartbeat_group_attrs[] = {
 	NULL,
 };
 
-static struct configfs_item_operations o2hb_hearbeat_group_item_ops = {
+static struct configfs_item_operations o2hb_heartbeat_group_item_ops = {
 	.show_attribute		= o2hb_heartbeat_group_show,
 	.store_attribute	= o2hb_heartbeat_group_store,
 };
@@ -2152,7 +2292,7 @@ static struct configfs_group_operations o2hb_heartbeat_group_group_ops = {
 
 static struct config_item_type o2hb_heartbeat_group_type = {
 	.ct_group_ops	= &o2hb_heartbeat_group_group_ops,
-	.ct_item_ops	= &o2hb_hearbeat_group_item_ops,
+	.ct_item_ops	= &o2hb_heartbeat_group_item_ops,
 	.ct_attrs	= o2hb_heartbeat_group_attrs,
 	.ct_owner	= THIS_MODULE,
 };
@@ -2184,7 +2324,7 @@ void o2hb_free_hb_set(struct config_group *group)
 	kfree(hs);
 }
 
-/* hb callback registration and issueing */
+/* hb callback registration and issuing */
 
 static struct o2hb_callback *hbcall_from_type(enum o2hb_callback_type type)
 {
@@ -2209,70 +2349,150 @@ void o2hb_setup_callback(struct o2hb_callback_func *hc,
 }
 EXPORT_SYMBOL_GPL(o2hb_setup_callback);
 
-static struct o2hb_region *o2hb_find_region(const char *region_uuid)
+/*
+ * In local heartbeat mode, region_uuid passed matches the dlm domain name.
+ * In global heartbeat mode, region_uuid passed is NULL.
+ *
+ * In local, we only pin the matching region. In global we pin all the active
+ * regions.
+ */
+static int o2hb_region_pin(const char *region_uuid)
 {
-	struct o2hb_region *p, *reg = NULL;
+	int ret = 0, found = 0;
+	struct o2hb_region *reg;
+	char *uuid;
 
 	assert_spin_locked(&o2hb_live_lock);
 
-	list_for_each_entry(p, &o2hb_all_regions, hr_all_item) {
-		if (!strcmp(region_uuid, config_item_name(&p->hr_item))) {
-			reg = p;
-			break;
+	list_for_each_entry(reg, &o2hb_all_regions, hr_all_item) {
+		if (reg->hr_item_dropped)
+			continue;
+
+		uuid = config_item_name(&reg->hr_item);
+
+		/* local heartbeat */
+		if (region_uuid) {
+			if (strcmp(region_uuid, uuid))
+				continue;
+			found = 1;
+		}
+
+		if (reg->hr_item_pinned || reg->hr_item_dropped)
+			goto skip_pin;
+
+		/* Ignore ENOENT only for local hb (userdlm domain) */
+		ret = o2nm_depend_item(&reg->hr_item);
+		if (!ret) {
+			mlog(ML_CLUSTER, "Pin region %s\n", uuid);
+			reg->hr_item_pinned = 1;
+		} else {
+			if (ret == -ENOENT && found)
+				ret = 0;
+			else {
+				mlog(ML_ERROR, "Pin region %s fails with %d\n",
+				     uuid, ret);
+				break;
+			}
 		}
+skip_pin:
+		if (found)
+			break;
 	}
 
-	return reg;
+	return ret;
 }
 
-static int o2hb_region_get(const char *region_uuid)
+/*
+ * In local heartbeat mode, region_uuid passed matches the dlm domain name.
+ * In global heartbeat mode, region_uuid passed is NULL.
+ *
+ * In local, we only unpin the matching region. In global we unpin all the
+ * active regions.
+ */
+static void o2hb_region_unpin(const char *region_uuid)
 {
-	int ret = 0;
 	struct o2hb_region *reg;
+	char *uuid;
+	int found = 0;
 
-	spin_lock(&o2hb_live_lock);
-
-	reg = o2hb_find_region(region_uuid);
-	if (!reg)
-		ret = -ENOENT;
-	spin_unlock(&o2hb_live_lock);
-
-	if (ret)
-		goto out;
+	assert_spin_locked(&o2hb_live_lock);
 
-	ret = o2nm_depend_this_node();
-	if (ret)
-		goto out;
+	list_for_each_entry(reg, &o2hb_all_regions, hr_all_item) {
+		if (reg->hr_item_dropped)
+			continue;
 
-	ret = o2nm_depend_item(&reg->hr_item);
-	if (ret)
-		o2nm_undepend_this_node();
+		uuid = config_item_name(&reg->hr_item);
+		if (region_uuid) {
+			if (strcmp(region_uuid, uuid))
+				continue;
+			found = 1;
+		}
 
-out:
-	return ret;
+		if (reg->hr_item_pinned) {
+			mlog(ML_CLUSTER, "Unpin region %s\n", uuid);
+			o2nm_undepend_item(&reg->hr_item);
+			reg->hr_item_pinned = 0;
+		}
+		if (found)
+			break;
+	}
 }
 
-static void o2hb_region_put(const char *region_uuid)
+static int o2hb_region_inc_user(const char *region_uuid)
 {
-	struct o2hb_region *reg;
+	int ret = 0;
 
 	spin_lock(&o2hb_live_lock);
 
-	reg = o2hb_find_region(region_uuid);
+	/* local heartbeat */
+	if (!o2hb_global_heartbeat_active()) {
+	    ret = o2hb_region_pin(region_uuid);
+	    goto unlock;
+	}
+
+	/*
+	 * if global heartbeat active and this is the first dependent user,
+	 * pin all regions if quorum region count <= CUT_OFF
+	 */
+	o2hb_dependent_users++;
+	if (o2hb_dependent_users > 1)
+		goto unlock;
+
+	if (bitmap_weight(o2hb_quorum_region_bitmap,
+			   O2NM_MAX_REGIONS) <= O2HB_PIN_CUT_OFF)
+		ret = o2hb_region_pin(NULL);
 
+unlock:
 	spin_unlock(&o2hb_live_lock);
+	return ret;
+}
 
-	if (reg) {
-		o2nm_undepend_item(&reg->hr_item);
-		o2nm_undepend_this_node();
+void o2hb_region_dec_user(const char *region_uuid)
+{
+	spin_lock(&o2hb_live_lock);
+
+	/* local heartbeat */
+	if (!o2hb_global_heartbeat_active()) {
+	    o2hb_region_unpin(region_uuid);
+	    goto unlock;
 	}
+
+	/*
+	 * if global heartbeat active and there are no dependent users,
+	 * unpin all quorum regions
+	 */
+	o2hb_dependent_users--;
+	if (!o2hb_dependent_users)
+		o2hb_region_unpin(NULL);
+
+unlock:
+	spin_unlock(&o2hb_live_lock);
 }
 
 int o2hb_register_callback(const char *region_uuid,
 			   struct o2hb_callback_func *hc)
 {
-	struct o2hb_callback_func *tmp;
-	struct list_head *iter;
+	struct o2hb_callback_func *f;
 	struct o2hb_callback *hbcall;
 	int ret;
 
@@ -2286,17 +2506,18 @@ int o2hb_register_callback(const char *region_uuid,
 	}
 
 	if (region_uuid) {
-		ret = o2hb_region_get(region_uuid);
-		if (ret)
+		ret = o2hb_region_inc_user(region_uuid);
+		if (ret) {
+			mlog_errno(ret);
 			goto out;
+		}
 	}
 
 	down_write(&o2hb_callback_sem);
 
-	list_for_each(iter, &hbcall->list) {
-		tmp = list_entry(iter, struct o2hb_callback_func, hc_item);
-		if (hc->hc_priority < tmp->hc_priority) {
-			list_add_tail(&hc->hc_item, iter);
+	list_for_each_entry(f, &hbcall->list, hc_item) {
+		if (hc->hc_priority < f->hc_priority) {
+			list_add_tail(&hc->hc_item, &f->hc_item);
 			break;
 		}
 	}
@@ -2306,7 +2527,7 @@ int o2hb_register_callback(const char *region_uuid,
 	up_write(&o2hb_callback_sem);
 	ret = 0;
 out:
-	mlog(ML_HEARTBEAT, "returning %d on behalf of %p for funcs %p\n",
+	mlog(ML_CLUSTER, "returning %d on behalf of %p for funcs %p\n",
 	     ret, __builtin_return_address(0), hc);
 	return ret;
 }
@@ -2317,7 +2538,7 @@ void o2hb_unregister_callback(const char *region_uuid,
 {
 	BUG_ON(hc->hc_magic != O2HB_CB_MAGIC);
 
-	mlog(ML_HEARTBEAT, "on behalf of %p for funcs %p\n",
+	mlog(ML_CLUSTER, "on behalf of %p for funcs %p\n",
 	     __builtin_return_address(0), hc);
 
 	/* XXX Can this happen _with_ a region reference? */
@@ -2325,7 +2546,7 @@ void o2hb_unregister_callback(const char *region_uuid,
 		return;
 
 	if (region_uuid)
-		o2hb_region_put(region_uuid);
+		o2hb_region_dec_user(region_uuid);
 
 	down_write(&o2hb_callback_sem);
 
@@ -2413,6 +2634,9 @@ int o2hb_get_all_regions(char *region_uuids, u8 max_regions)
 
 	p = region_uuids;
 	list_for_each_entry(reg, &o2hb_all_regions, hr_all_item) {
+		if (reg->hr_item_dropped)
+			continue;
+
 		mlog(0, "Region: %s\n", config_item_name(&reg->hr_item));
 		if (numregs < max_regions) {
 			memcpy(p, config_item_name(&reg->hr_item),