heartbeat.c

ocfs1.2.7 源码

	o2hb_compute_request_limits(reg, max_slots, &num_bios, &slots_per_bio);

	o2hb_mlog_blocking(reg, &start, "allocating bios for read");
	bios = kcalloc(num_bios, sizeof(struct bio *), GFP_KERNEL);
	o2hb_mlog_blocking_done(reg, &start);
	if (!bios) {
		status = -ENOMEM;
		mlog_errno(status);
		return status;
	}

	o2hb_bio_wait_init(&wc, num_bios);

	num_slots = slots_per_bio;
	for(i = 0; i < num_bios; i++) {
		start_slot = i * slots_per_bio;

		/* adjust num_slots at last bio */
		if (max_slots < (start_slot + num_slots))
			num_slots = max_slots - start_slot;

		bio = o2hb_setup_one_bio(reg, &wc, start_slot, num_slots, 0);
		if (IS_ERR(bio)) {
			o2hb_bio_wait_dec(&wc, num_bios - i);

			status = PTR_ERR(bio);
			mlog_errno(status);
			goto bail_and_wait;
		}
		bios[i] = bio;

		o2hb_mlog_blocking(reg, &start, "submit_bio for read");
		submit_bio(READ, bio);
		o2hb_mlog_blocking_done(reg, &start);
	}

	status = 0;

bail_and_wait:
	o2hb_mlog_blocking(reg, &start, "waiting for read completion");
	o2hb_wait_on_io(reg, &wc);
	if (wc.wc_error && !status)
		status = wc.wc_error;
	o2hb_mlog_blocking_done(reg, &start);

	if (bios) {
		for(i = 0; i < num_bios; i++)
			if (bios[i])
				bio_put(bios[i]);
		kfree(bios);
	}

	return status;
}

static int o2hb_issue_node_write(struct o2hb_region *reg,
				 struct bio **write_bio,
				 struct o2hb_bio_wait_ctxt *write_wc)
{
	int status;
	unsigned int slot;
	struct bio *bio;
	struct timeval start;

	o2hb_bio_wait_init(write_wc, 1);

	slot = o2nm_this_node();

	bio = o2hb_setup_one_bio(reg, write_wc, slot, 1, 1);
	if (IS_ERR(bio)) {
		status = PTR_ERR(bio);
		mlog_errno(status);
		goto bail;
	}

	o2hb_mlog_blocking(reg, &start, "submit_bio for write");
	submit_bio(WRITE, bio);
	o2hb_mlog_blocking_done(reg, &start);

	*write_bio = bio;
	status = 0;
bail:
	return status;
}

static u32 o2hb_compute_block_crc_le(struct o2hb_region *reg,
				     struct o2hb_disk_heartbeat_block *hb_block)
{
	__le32 old_cksum;
	u32 ret;

	/* We want to compute the block crc with a 0 value in the
	 * hb_cksum field. Save it off here and replace after the
	 * crc. */
	old_cksum = hb_block->hb_cksum;
	hb_block->hb_cksum = 0;

	ret = crc32_le(0, (unsigned char *) hb_block, reg->hr_block_bytes);

	hb_block->hb_cksum = old_cksum;

	return ret;
}

static void o2hb_dump_slot(struct o2hb_disk_heartbeat_block *hb_block)
{
	mlog(ML_ERROR, "Dump slot information: seq = 0x%"MLFx64", node = %u, "
	     "cksum = 0x%x, generation 0x%"MLFx64"\n",
	     le64_to_cpu(hb_block->hb_seq), hb_block->hb_node,
	     le32_to_cpu(hb_block->hb_cksum),
	     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);
	hb_block->hb_dead_ms = cpu_to_le32(o2hb_dead_threshold * O2HB_REGION_TIMEOUT_MS);

	/* 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%"MLFx64", cksum = 0x%x\n",
	     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;
	unsigned int dead_ms = o2hb_dead_threshold * O2HB_REGION_TIMEOUT_MS;
	unsigned int slot_dead_ms;

	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%"MLFx64" "
		     "to 0x%"MLFx64")\n", slot->ds_node_num,
		     slot->ds_last_generation,
		     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%"MLFx64" cksum 0x%x "
	     "seq %"MLFu64" last %"MLFu64" changed %u equal %u\n",
	     slot->ds_node_num, slot->ds_last_generation,
	     le32_to_cpu(hb_block->hb_cksum), le64_to_cpu(hb_block->hb_seq), 
	     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%"MLFx64") joined my "
		     "region\n", slot->ds_node_num, 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;

		/* We want to be sure that all nodes agree on the
		 * number of milliseconds before a node will be
		 * considered dead. The self-fencing timeout is
		 * computed from this value, and a discrepancy might
		 * result in heartbeat calling a node dead when it
		 * hasn't self-fenced yet. */
		slot_dead_ms = le32_to_cpu(hb_block->hb_dead_ms);
		if (slot_dead_ms && slot_dead_ms != dead_ms) {
			/* TODO: Perhaps we can fail the region here. */
			mlog(ML_ERROR, "Node %d on device %s has a dead count "
			     "of %u ms, but our count is %u ms.\n"
			     "Please double check your configuration values "
			     "for 'O2CB_HEARTBEAT_THRESHOLD'\n",
			     slot->ds_node_num, reg->hr_dev_name, slot_dead_ms,
			     dead_ms);
		}
		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;
	struct timeval start;

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