heartbeat.c

LINUX 2.6.17.4的源码

	mlog(ML_ERROR, "Dump slot information: seq = 0x%llx, node = %u, "
	     "cksum = 0x%x, generation 0x%llx\n",
	     (long long)le64_to_cpu(hb_block->hb_seq),
	     hb_block->hb_node, le32_to_cpu(hb_block->hb_cksum),
	     (long long)le64_to_cpu(hb_block->hb_generation));
}

static int o2hb_verify_crc(struct o2hb_region *reg,
			   struct o2hb_disk_heartbeat_block *hb_block)
{
	u32 read, computed;

	read = le32_to_cpu(hb_block->hb_cksum);
	computed = o2hb_compute_block_crc_le(reg, hb_block);

	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)
{
	int node_num, ret;
	struct o2hb_disk_slot *slot;
	struct o2hb_disk_heartbeat_block *hb_block;

	node_num = o2nm_this_node();

	ret = 1;
	slot = &reg->hr_slots[node_num];
	/* Don't check on our 1st timestamp */
	if (slot->ds_last_time) {
		hb_block = slot->ds_raw_block;

		if (le64_to_cpu(hb_block->hb_seq) != slot->ds_last_time)
			ret = 0;
	}

	return ret;
}

static inline void o2hb_prepare_block(struct o2hb_region *reg,
				      u64 generation)
{
	int node_num;
	u64 cputime;
	struct o2hb_disk_slot *slot;
	struct o2hb_disk_heartbeat_block *hb_block;

	node_num = o2nm_this_node();
	slot = &reg->hr_slots[node_num];

	hb_block = (struct o2hb_disk_heartbeat_block *)slot->ds_raw_block;
	memset(hb_block, 0, reg->hr_block_bytes);
	/* TODO: time stuff */
	cputime = CURRENT_TIME.tv_sec;
	if (!cputime)
		cputime = 1;

	hb_block->hb_seq = cpu_to_le64(cputime);
	hb_block->hb_node = node_num;
	hb_block->hb_generation = cpu_to_le64(generation);

	/* This step must always happen last! */
	hb_block->hb_cksum = cpu_to_le32(o2hb_compute_block_crc_le(reg,
								   hb_block));

	mlog(ML_HB_BIO, "our node generation = 0x%llx, cksum = 0x%x\n",
	     (long long)cpu_to_le64(generation),
	     le32_to_cpu(hb_block->hb_cksum));
}

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);
		mlog(ML_HEARTBEAT, "calling funcs %p\n", f);
		(f->hc_func)(node, idx, f->hc_data);
	}
}

/* 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. */
	down_write(&o2hb_callback_sem);

	spin_lock(&o2hb_live_lock);
	while (!list_empty(&o2hb_node_events)
	       && !list_empty(&queued_event->hn_item)) {
		event = list_entry(o2hb_node_events.next,
				   struct o2hb_node_event,
				   hn_item);
		list_del_init(&event->hn_item);
		spin_unlock(&o2hb_live_lock);

		mlog(ML_HEARTBEAT, "Node %s event for %d\n",
		     event->hn_event_type == O2HB_NODE_UP_CB ? "UP" : "DOWN",
		     event->hn_node_num);

		hbcall = hbcall_from_type(event->hn_event_type);

		/* We should *never* have gotten on to the list with a
		 * bad type... This isn't something that we should try
		 * to recover from. */
		BUG_ON(IS_ERR(hbcall));

		o2hb_fire_callbacks(hbcall, event->hn_node, event->hn_node_num);

		spin_lock(&o2hb_live_lock);
	}
	spin_unlock(&o2hb_live_lock);

	up_write(&o2hb_callback_sem);
}

static void o2hb_queue_node_event(struct o2hb_node_event *event,
				  enum o2hb_callback_type type,
				  struct o2nm_node *node,
				  int node_num)
{
	assert_spin_locked(&o2hb_live_lock);

	event->hn_event_type = type;
	event->hn_node = node;
	event->hn_node_num = node_num;

	mlog(ML_HEARTBEAT, "Queue node %s event for node %d\n",
	     type == O2HB_NODE_UP_CB ? "UP" : "DOWN", node_num);

	list_add_tail(&event->hn_item, &o2hb_node_events);
}

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;

	node = o2nm_get_node_by_num(slot->ds_node_num);
	if (!node)
		return;

	spin_lock(&o2hb_live_lock);
	if (!list_empty(&slot->ds_live_item)) {
		mlog(ML_HEARTBEAT, "Shutdown, node %d leaves region\n",
		     slot->ds_node_num);

		list_del_init(&slot->ds_live_item);

		if (list_empty(&o2hb_live_slots[slot->ds_node_num])) {
			clear_bit(slot->ds_node_num, o2hb_live_node_bitmap);

			o2hb_queue_node_event(&event, O2HB_NODE_DOWN_CB, node,
					      slot->ds_node_num);
		}
	}
	spin_unlock(&o2hb_live_lock);

	o2hb_run_event_list(&event);

	o2nm_node_put(node);
}

static int o2hb_check_slot(struct o2hb_region *reg,
			   struct o2hb_disk_slot *slot)
{
	int changed = 0, gen_changed = 0;
	struct o2hb_node_event event =
		{ .hn_item = LIST_HEAD_INIT(event.hn_item), };
	struct o2nm_node *node;
	struct o2hb_disk_heartbeat_block *hb_block = reg->hr_tmp_block;
	u64 cputime;

	memcpy(hb_block, slot->ds_raw_block, reg->hr_block_bytes);

	/* Is this correct? Do we assume that the node doesn't exist
	 * if we're not configured for him? */
	node = o2nm_get_node_by_num(slot->ds_node_num);
	if (!node)
		return 0;

	if (!o2hb_verify_crc(reg, hb_block)) {
		/* all paths from here will drop o2hb_live_lock for
		 * us. */
		spin_lock(&o2hb_live_lock);

		/* Don't print an error on the console in this case -
		 * a freshly formatted heartbeat area will not have a
		 * crc set on it. */
		if (list_empty(&slot->ds_live_item))
			goto out;

		/* The node is live but pushed out a bad crc. We
		 * consider it a transient miss but don't populate any
		 * other values as they may be junk. */
		mlog(ML_ERROR, "Node %d has written a bad crc to %s\n",
		     slot->ds_node_num, reg->hr_dev_name);
		o2hb_dump_slot(hb_block);

		slot->ds_equal_samples++;
		goto fire_callbacks;
	}

	/* we don't care if these wrap.. the state transitions below
	 * clear at the right places */
	cputime = le64_to_cpu(hb_block->hb_seq);
	if (slot->ds_last_time != cputime)
		slot->ds_changed_samples++;
	else
		slot->ds_equal_samples++;
	slot->ds_last_time = cputime;

	/* The node changed heartbeat generations. We assume this to
	 * mean it dropped off but came back before we timed out. We
	 * want to consider it down for the time being but don't want
	 * to lose any changed_samples state we might build up to
	 * considering it live again. */
	if (slot->ds_last_generation != le64_to_cpu(hb_block->hb_generation)) {
		gen_changed = 1;
		slot->ds_equal_samples = 0;
		mlog(ML_HEARTBEAT, "Node %d changed generation (0x%llx "
		     "to 0x%llx)\n", slot->ds_node_num,
		     (long long)slot->ds_last_generation,
		     (long long)le64_to_cpu(hb_block->hb_generation));
	}

	slot->ds_last_generation = le64_to_cpu(hb_block->hb_generation);

	mlog(ML_HEARTBEAT, "Slot %d gen 0x%llx cksum 0x%x "
	     "seq %llu last %llu changed %u equal %u\n",
	     slot->ds_node_num, (long long)slot->ds_last_generation,
	     le32_to_cpu(hb_block->hb_cksum),
	     (unsigned long long)le64_to_cpu(hb_block->hb_seq), 
	     (unsigned long long)slot->ds_last_time, slot->ds_changed_samples,
	     slot->ds_equal_samples);

	spin_lock(&o2hb_live_lock);

fire_callbacks:
	/* dead nodes only come to life after some number of
	 * changes at any time during their dead time */
	if (list_empty(&slot->ds_live_item) &&
	    slot->ds_changed_samples >= O2HB_LIVE_THRESHOLD) {
		mlog(ML_HEARTBEAT, "Node %d (id 0x%llx) joined my region\n",
		     slot->ds_node_num, (long long)slot->ds_last_generation);

		/* first on the list generates a callback */
		if (list_empty(&o2hb_live_slots[slot->ds_node_num])) {
			set_bit(slot->ds_node_num, o2hb_live_node_bitmap);

			o2hb_queue_node_event(&event, O2HB_NODE_UP_CB, node,
					      slot->ds_node_num);

			changed = 1;
		}

		list_add_tail(&slot->ds_live_item,
			      &o2hb_live_slots[slot->ds_node_num]);

		slot->ds_equal_samples = 0;
		goto out;
	}

	/* if the list is dead, we're done.. */
	if (list_empty(&slot->ds_live_item))
		goto out;

	/* live nodes only go dead after enough consequtive missed
	 * samples..  reset the missed counter whenever we see
	 * activity */
	if (slot->ds_equal_samples >= o2hb_dead_threshold || gen_changed) {
		mlog(ML_HEARTBEAT, "Node %d left my region\n",
		     slot->ds_node_num);

		/* last off the live_slot generates a callback */
		list_del_init(&slot->ds_live_item);
		if (list_empty(&o2hb_live_slots[slot->ds_node_num])) {
			clear_bit(slot->ds_node_num, o2hb_live_node_bitmap);

			o2hb_queue_node_event(&event, O2HB_NODE_DOWN_CB, node,
					      slot->ds_node_num);

			changed = 1;
		}

		/* We don't clear this because the node is still
		 * actually writing new blocks. */
		if (!gen_changed)
			slot->ds_changed_samples = 0;
		goto out;
	}
	if (slot->ds_changed_samples) {
		slot->ds_changed_samples = 0;
		slot->ds_equal_samples = 0;
	}
out:
	spin_unlock(&o2hb_live_lock);

	o2hb_run_event_list(&event);

	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)
{
	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;
}

static int o2hb_do_disk_heartbeat(struct o2hb_region *reg)
{
	int i, ret, highest_node, change = 0;
	unsigned long configured_nodes[BITS_TO_LONGS(O2NM_MAX_NODES)];
	struct bio *write_bio;
	struct o2hb_bio_wait_ctxt write_wc;

	ret = o2nm_configured_node_map(configured_nodes,
				       sizeof(configured_nodes));
	if (ret) {
		mlog_errno(ret);
		return ret;
	}

	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;
	}

	/* No sense in reading the slots of nodes that don't exist
	 * yet. Of course, if the node definitions have holes in them
	 * then we're reading an empty slot anyway... Consider this
	 * best-effort. */
	ret = o2hb_read_slots(reg, highest_node + 1);
	if (ret < 0) {
		mlog_errno(ret);
		return ret;
	}

	/* 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);

	/* 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_bio, &write_wc);
	if (ret < 0) {
		mlog_errno(ret);
		return ret;
	}

	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]);
	}

	/*
	 * We have to be sure we've advertised ourselves on disk
	 * before we can go to steady state.  This ensures that
	 * people we find in our steady state have seen us.
	 */
	o2hb_wait_on_io(reg, &write_wc);
	bio_put(write_bio);
	if (write_wc.wc_error) {
		/* Do not re-arm the write timeout on I/O error - we
		 * can't be sure that the new block ever made it to
		 * disk */
		mlog(ML_ERROR, "Write error %d on device \"%s\"\n",
		     write_wc.wc_error, reg->hr_dev_name);
		return write_wc.wc_error;
	}

	o2hb_arm_write_timeout(reg);

	/* 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))
			wake_up(&o2hb_steady_queue);
	}

	return 0;
}

/* Subtract b from a, storing the result in a. a *must* have a larger
 * value than b. */
static void o2hb_tv_subtract(struct timeval *a,
			     struct timeval *b)
{
	/* just return 0 when a is after b */
	if (a->tv_sec < b->tv_sec ||
	    (a->tv_sec == b->tv_sec && a->tv_usec < b->tv_usec)) {
		a->tv_sec = 0;
		a->tv_usec = 0;
		return;
	}

	a->tv_sec -= b->tv_sec;
	a->tv_usec -= b->tv_usec;
	while ( a->tv_usec < 0 ) {
		a->tv_sec--;
		a->tv_usec += 1000000;
	}
}

static unsigned int o2hb_elapsed_msecs(struct timeval *start,
				       struct timeval *end)
{
	struct timeval res = *end;

	o2hb_tv_subtract(&res, start);

	return res.tv_sec * 1000 + res.tv_usec / 1000;
}

/*
 * we ride the region ref that the region dir holds.  before the region
 * dir is removed and drops it ref it will wait to tear down this
 * thread.