Adding upstream version 6.1.76.upstream/6.1.76upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1602 insertions, 0 deletions

diff --git a/drivers/md/md-cluster.c b/drivers/md/md-cluster.c
new file mode 100644
index 000000000..10e0c5381
--- /dev/null
+++ b/drivers/md/md-cluster.c
@@ -0,0 +1,1602 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2015, SUSE
+ */
+
+
+#include <linux/module.h>
+#include <linux/kthread.h>
+#include <linux/dlm.h>
+#include <linux/sched.h>
+#include <linux/raid/md_p.h>
+#include "md.h"
+#include "md-bitmap.h"
+#include "md-cluster.h"
+
+#define LVB_SIZE	64
+#define NEW_DEV_TIMEOUT 5000
+
+struct dlm_lock_resource {
+	dlm_lockspace_t *ls;
+	struct dlm_lksb lksb;
+	char *name; /* lock name. */
+	uint32_t flags; /* flags to pass to dlm_lock() */
+	wait_queue_head_t sync_locking; /* wait queue for synchronized locking */
+	bool sync_locking_done;
+	void (*bast)(void *arg, int mode); /* blocking AST function pointer*/
+	struct mddev *mddev; /* pointing back to mddev. */
+	int mode;
+};
+
+struct resync_info {
+	__le64 lo;
+	__le64 hi;
+};
+
+/* md_cluster_info flags */
+#define		MD_CLUSTER_WAITING_FOR_NEWDISK		1
+#define		MD_CLUSTER_SUSPEND_READ_BALANCING	2
+#define		MD_CLUSTER_BEGIN_JOIN_CLUSTER		3
+
+/* Lock the send communication. This is done through
+ * bit manipulation as opposed to a mutex in order to
+ * accommodate lock and hold. See next comment.
+ */
+#define		MD_CLUSTER_SEND_LOCK			4
+/* If cluster operations (such as adding a disk) must lock the
+ * communication channel, so as to perform extra operations
+ * (update metadata) and no other operation is allowed on the
+ * MD. Token needs to be locked and held until the operation
+ * completes witha md_update_sb(), which would eventually release
+ * the lock.
+ */
+#define		MD_CLUSTER_SEND_LOCKED_ALREADY		5
+/* We should receive message after node joined cluster and
+ * set up all the related infos such as bitmap and personality */
+#define		MD_CLUSTER_ALREADY_IN_CLUSTER		6
+#define		MD_CLUSTER_PENDING_RECV_EVENT		7
+#define 	MD_CLUSTER_HOLDING_MUTEX_FOR_RECVD		8
+
+struct md_cluster_info {
+	struct mddev *mddev; /* the md device which md_cluster_info belongs to */
+	/* dlm lock space and resources for clustered raid. */
+	dlm_lockspace_t *lockspace;
+	int slot_number;
+	struct completion completion;
+	struct mutex recv_mutex;
+	struct dlm_lock_resource *bitmap_lockres;
+	struct dlm_lock_resource **other_bitmap_lockres;
+	struct dlm_lock_resource *resync_lockres;
+	struct list_head suspend_list;
+
+	spinlock_t suspend_lock;
+	/* record the region which write should be suspended */
+	sector_t suspend_lo;
+	sector_t suspend_hi;
+	int suspend_from; /* the slot which broadcast suspend_lo/hi */
+
+	struct md_thread *recovery_thread;
+	unsigned long recovery_map;
+	/* communication loc resources */
+	struct dlm_lock_resource *ack_lockres;
+	struct dlm_lock_resource *message_lockres;
+	struct dlm_lock_resource *token_lockres;
+	struct dlm_lock_resource *no_new_dev_lockres;
+	struct md_thread *recv_thread;
+	struct completion newdisk_completion;
+	wait_queue_head_t wait;
+	unsigned long state;
+	/* record the region in RESYNCING message */
+	sector_t sync_low;
+	sector_t sync_hi;
+};
+
+enum msg_type {
+	METADATA_UPDATED = 0,
+	RESYNCING,
+	NEWDISK,
+	REMOVE,
+	RE_ADD,
+	BITMAP_NEEDS_SYNC,
+	CHANGE_CAPACITY,
+	BITMAP_RESIZE,
+};
+
+struct cluster_msg {
+	__le32 type;
+	__le32 slot;
+	/* TODO: Unionize this for smaller footprint */
+	__le64 low;
+	__le64 high;
+	char uuid[16];
+	__le32 raid_slot;
+};
+
+static void sync_ast(void *arg)
+{
+	struct dlm_lock_resource *res;
+
+	res = arg;
+	res->sync_locking_done = true;
+	wake_up(&res->sync_locking);
+}
+
+static int dlm_lock_sync(struct dlm_lock_resource *res, int mode)
+{
+	int ret = 0;
+
+	ret = dlm_lock(res->ls, mode, &res->lksb,
+			res->flags, res->name, strlen(res->name),
+			0, sync_ast, res, res->bast);
+	if (ret)
+		return ret;
+	wait_event(res->sync_locking, res->sync_locking_done);
+	res->sync_locking_done = false;
+	if (res->lksb.sb_status == 0)
+		res->mode = mode;
+	return res->lksb.sb_status;
+}
+
+static int dlm_unlock_sync(struct dlm_lock_resource *res)
+{
+	return dlm_lock_sync(res, DLM_LOCK_NL);
+}
+
+/*
+ * An variation of dlm_lock_sync, which make lock request could
+ * be interrupted
+ */
+static int dlm_lock_sync_interruptible(struct dlm_lock_resource *res, int mode,
+				       struct mddev *mddev)
+{
+	int ret = 0;
+
+	ret = dlm_lock(res->ls, mode, &res->lksb,
+			res->flags, res->name, strlen(res->name),
+			0, sync_ast, res, res->bast);
+	if (ret)
+		return ret;
+
+	wait_event(res->sync_locking, res->sync_locking_done
+				      || kthread_should_stop()
+				      || test_bit(MD_CLOSING, &mddev->flags));
+	if (!res->sync_locking_done) {
+		/*
+		 * the convert queue contains the lock request when request is
+		 * interrupted, and sync_ast could still be run, so need to
+		 * cancel the request and reset completion
+		 */
+		ret = dlm_unlock(res->ls, res->lksb.sb_lkid, DLM_LKF_CANCEL,
+			&res->lksb, res);
+		res->sync_locking_done = false;
+		if (unlikely(ret != 0))
+			pr_info("failed to cancel previous lock request "
+				 "%s return %d\n", res->name, ret);
+		return -EPERM;
+	} else
+		res->sync_locking_done = false;
+	if (res->lksb.sb_status == 0)
+		res->mode = mode;
+	return res->lksb.sb_status;
+}
+
+static struct dlm_lock_resource *lockres_init(struct mddev *mddev,
+		char *name, void (*bastfn)(void *arg, int mode), int with_lvb)
+{
+	struct dlm_lock_resource *res = NULL;
+	int ret, namelen;
+	struct md_cluster_info *cinfo = mddev->cluster_info;
+
+	res = kzalloc(sizeof(struct dlm_lock_resource), GFP_KERNEL);
+	if (!res)
+		return NULL;
+	init_waitqueue_head(&res->sync_locking);
+	res->sync_locking_done = false;
+	res->ls = cinfo->lockspace;
+	res->mddev = mddev;
+	res->mode = DLM_LOCK_IV;
+	namelen = strlen(name);
+	res->name = kzalloc(namelen + 1, GFP_KERNEL);
+	if (!res->name) {
+		pr_err("md-cluster: Unable to allocate resource name for resource %s\n", name);
+		goto out_err;
+	}
+	strscpy(res->name, name, namelen + 1);
+	if (with_lvb) {
+		res->lksb.sb_lvbptr = kzalloc(LVB_SIZE, GFP_KERNEL);
+		if (!res->lksb.sb_lvbptr) {
+			pr_err("md-cluster: Unable to allocate LVB for resource %s\n", name);
+			goto out_err;
+		}
+		res->flags = DLM_LKF_VALBLK;
+	}
+
+	if (bastfn)
+		res->bast = bastfn;
+
+	res->flags |= DLM_LKF_EXPEDITE;
+
+	ret = dlm_lock_sync(res, DLM_LOCK_NL);
+	if (ret) {
+		pr_err("md-cluster: Unable to lock NL on new lock resource %s\n", name);
+		goto out_err;
+	}
+	res->flags &= ~DLM_LKF_EXPEDITE;
+	res->flags |= DLM_LKF_CONVERT;
+
+	return res;
+out_err:
+	kfree(res->lksb.sb_lvbptr);
+	kfree(res->name);
+	kfree(res);
+	return NULL;
+}
+
+static void lockres_free(struct dlm_lock_resource *res)
+{
+	int ret = 0;
+
+	if (!res)
+		return;
+
+	/*
+	 * use FORCEUNLOCK flag, so we can unlock even the lock is on the
+	 * waiting or convert queue
+	 */
+	ret = dlm_unlock(res->ls, res->lksb.sb_lkid, DLM_LKF_FORCEUNLOCK,
+		&res->lksb, res);
+	if (unlikely(ret != 0))
+		pr_err("failed to unlock %s return %d\n", res->name, ret);
+	else
+		wait_event(res->sync_locking, res->sync_locking_done);
+
+	kfree(res->name);
+	kfree(res->lksb.sb_lvbptr);
+	kfree(res);
+}
+
+static void add_resync_info(struct dlm_lock_resource *lockres,
+			    sector_t lo, sector_t hi)
+{
+	struct resync_info *ri;
+
+	ri = (struct resync_info *)lockres->lksb.sb_lvbptr;
+	ri->lo = cpu_to_le64(lo);
+	ri->hi = cpu_to_le64(hi);
+}
+
+static int read_resync_info(struct mddev *mddev,
+			    struct dlm_lock_resource *lockres)
+{
+	struct resync_info ri;
+	struct md_cluster_info *cinfo = mddev->cluster_info;
+	int ret = 0;
+
+	dlm_lock_sync(lockres, DLM_LOCK_CR);
+	memcpy(&ri, lockres->lksb.sb_lvbptr, sizeof(struct resync_info));
+	if (le64_to_cpu(ri.hi) > 0) {
+		cinfo->suspend_hi = le64_to_cpu(ri.hi);
+		cinfo->suspend_lo = le64_to_cpu(ri.lo);
+		ret = 1;
+	}
+	dlm_unlock_sync(lockres);
+	return ret;
+}
+
+static void recover_bitmaps(struct md_thread *thread)
+{
+	struct mddev *mddev = thread->mddev;
+	struct md_cluster_info *cinfo = mddev->cluster_info;
+	struct dlm_lock_resource *bm_lockres;
+	char str[64];
+	int slot, ret;
+	sector_t lo, hi;
+
+	while (cinfo->recovery_map) {
+		slot = fls64((u64)cinfo->recovery_map) - 1;
+
+		snprintf(str, 64, "bitmap%04d", slot);
+		bm_lockres = lockres_init(mddev, str, NULL, 1);
+		if (!bm_lockres) {
+			pr_err("md-cluster: Cannot initialize bitmaps\n");
+			goto clear_bit;
+		}
+
+		ret = dlm_lock_sync_interruptible(bm_lockres, DLM_LOCK_PW, mddev);
+		if (ret) {
+			pr_err("md-cluster: Could not DLM lock %s: %d\n",
+					str, ret);
+			goto clear_bit;
+		}
+		ret = md_bitmap_copy_from_slot(mddev, slot, &lo, &hi, true);
+		if (ret) {
+			pr_err("md-cluster: Could not copy data from bitmap %d\n", slot);
+			goto clear_bit;
+		}
+
+		/* Clear suspend_area associated with the bitmap */
+		spin_lock_irq(&cinfo->suspend_lock);
+		cinfo->suspend_hi = 0;
+		cinfo->suspend_lo = 0;
+		cinfo->suspend_from = -1;
+		spin_unlock_irq(&cinfo->suspend_lock);
+
+		/* Kick off a reshape if needed */
+		if (test_bit(MD_RESYNCING_REMOTE, &mddev->recovery) &&
+		    test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
+		    mddev->reshape_position != MaxSector)
+			md_wakeup_thread(mddev->sync_thread);
+
+		if (hi > 0) {
+			if (lo < mddev->recovery_cp)
+				mddev->recovery_cp = lo;
+			/* wake up thread to continue resync in case resync
+			 * is not finished */
+			if (mddev->recovery_cp != MaxSector) {
+				/*
+				 * clear the REMOTE flag since we will launch
+				 * resync thread in current node.
+				 */
+				clear_bit(MD_RESYNCING_REMOTE,
+					  &mddev->recovery);
+				set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+				md_wakeup_thread(mddev->thread);
+			}
+		}
+clear_bit:
+		lockres_free(bm_lockres);
+		clear_bit(slot, &cinfo->recovery_map);
+	}
+}
+
+static void recover_prep(void *arg)
+{
+	struct mddev *mddev = arg;
+	struct md_cluster_info *cinfo = mddev->cluster_info;
+	set_bit(MD_CLUSTER_SUSPEND_READ_BALANCING, &cinfo->state);
+}
+
+static void __recover_slot(struct mddev *mddev, int slot)
+{
+	struct md_cluster_info *cinfo = mddev->cluster_info;
+
+	set_bit(slot, &cinfo->recovery_map);
+	if (!cinfo->recovery_thread) {
+		cinfo->recovery_thread = md_register_thread(recover_bitmaps,
+				mddev, "recover");
+		if (!cinfo->recovery_thread) {
+			pr_warn("md-cluster: Could not create recovery thread\n");
+			return;
+		}
+	}
+	md_wakeup_thread(cinfo->recovery_thread);
+}
+
+static void recover_slot(void *arg, struct dlm_slot *slot)
+{
+	struct mddev *mddev = arg;
+	struct md_cluster_info *cinfo = mddev->cluster_info;
+
+	pr_info("md-cluster: %s Node %d/%d down. My slot: %d. Initiating recovery.\n",
+			mddev->bitmap_info.cluster_name,
+			slot->nodeid, slot->slot,
+			cinfo->slot_number);
+	/* deduct one since dlm slot starts from one while the num of
+	 * cluster-md begins with 0 */
+	__recover_slot(mddev, slot->slot - 1);
+}
+
+static void recover_done(void *arg, struct dlm_slot *slots,
+		int num_slots, int our_slot,
+		uint32_t generation)
+{
+	struct mddev *mddev = arg;
+	struct md_cluster_info *cinfo = mddev->cluster_info;
+
+	cinfo->slot_number = our_slot;
+	/* completion is only need to be complete when node join cluster,
+	 * it doesn't need to run during another node's failure */
+	if (test_bit(MD_CLUSTER_BEGIN_JOIN_CLUSTER, &cinfo->state)) {
+		complete(&cinfo->completion);
+		clear_bit(MD_CLUSTER_BEGIN_JOIN_CLUSTER, &cinfo->state);
+	}
+	clear_bit(MD_CLUSTER_SUSPEND_READ_BALANCING, &cinfo->state);
+}
+
+/* the ops is called when node join the cluster, and do lock recovery
+ * if node failure occurs */
+static const struct dlm_lockspace_ops md_ls_ops = {
+	.recover_prep = recover_prep,
+	.recover_slot = recover_slot,
+	.recover_done = recover_done,
+};
+
+/*
+ * The BAST function for the ack lock resource
+ * This function wakes up the receive thread in
+ * order to receive and process the message.
+ */
+static void ack_bast(void *arg, int mode)
+{
+	struct dlm_lock_resource *res = arg;
+	struct md_cluster_info *cinfo = res->mddev->cluster_info;
+
+	if (mode == DLM_LOCK_EX) {
+		if (test_bit(MD_CLUSTER_ALREADY_IN_CLUSTER, &cinfo->state))
+			md_wakeup_thread(cinfo->recv_thread);
+		else
+			set_bit(MD_CLUSTER_PENDING_RECV_EVENT, &cinfo->state);
+	}
+}
+
+static void remove_suspend_info(struct mddev *mddev, int slot)
+{
+	struct md_cluster_info *cinfo = mddev->cluster_info;
+	mddev->pers->quiesce(mddev, 1);
+	spin_lock_irq(&cinfo->suspend_lock);
+	cinfo->suspend_hi = 0;
+	cinfo->suspend_lo = 0;
+	spin_unlock_irq(&cinfo->suspend_lock);
+	mddev->pers->quiesce(mddev, 0);
+}
+
+static void process_suspend_info(struct mddev *mddev,
+		int slot, sector_t lo, sector_t hi)
+{
+	struct md_cluster_info *cinfo = mddev->cluster_info;
+	struct mdp_superblock_1 *sb = NULL;
+	struct md_rdev *rdev;
+
+	if (!hi) {
+		/*
+		 * clear the REMOTE flag since resync or recovery is finished
+		 * in remote node.
+		 */
+		clear_bit(MD_RESYNCING_REMOTE, &mddev->recovery);
+		remove_suspend_info(mddev, slot);
+		set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+		md_wakeup_thread(mddev->thread);
+		return;
+	}
+
+	rdev_for_each(rdev, mddev)
+		if (rdev->raid_disk > -1 && !test_bit(Faulty, &rdev->flags)) {
+			sb = page_address(rdev->sb_page);
+			break;
+		}
+
+	/*
+	 * The bitmaps are not same for different nodes
+	 * if RESYNCING is happening in one node, then
+	 * the node which received the RESYNCING message
+	 * probably will perform resync with the region
+	 * [lo, hi] again, so we could reduce resync time
+	 * a lot if we can ensure that the bitmaps among
+	 * different nodes are match up well.
+	 *
+	 * sync_low/hi is used to record the region which
+	 * arrived in the previous RESYNCING message,
+	 *
+	 * Call md_bitmap_sync_with_cluster to clear NEEDED_MASK
+	 * and set RESYNC_MASK since  resync thread is running
+	 * in another node, so we don't need to do the resync
+	 * again with the same section.
+	 *
+	 * Skip md_bitmap_sync_with_cluster in case reshape
+	 * happening, because reshaping region is small and
+	 * we don't want to trigger lots of WARN.
+	 */
+	if (sb && !(le32_to_cpu(sb->feature_map) & MD_FEATURE_RESHAPE_ACTIVE))
+		md_bitmap_sync_with_cluster(mddev, cinfo->sync_low,
+					    cinfo->sync_hi, lo, hi);
+	cinfo->sync_low = lo;
+	cinfo->sync_hi = hi;
+
+	mddev->pers->quiesce(mddev, 1);
+	spin_lock_irq(&cinfo->suspend_lock);
+	cinfo->suspend_from = slot;
+	cinfo->suspend_lo = lo;
+	cinfo->suspend_hi = hi;
+	spin_unlock_irq(&cinfo->suspend_lock);
+	mddev->pers->quiesce(mddev, 0);
+}
+
+static void process_add_new_disk(struct mddev *mddev, struct cluster_msg *cmsg)
+{
+	char disk_uuid[64];
+	struct md_cluster_info *cinfo = mddev->cluster_info;
+	char event_name[] = "EVENT=ADD_DEVICE";
+	char raid_slot[16];
+	char *envp[] = {event_name, disk_uuid, raid_slot, NULL};
+	int len;
+
+	len = snprintf(disk_uuid, 64, "DEVICE_UUID=");
+	sprintf(disk_uuid + len, "%pU", cmsg->uuid);
+	snprintf(raid_slot, 16, "RAID_DISK=%d", le32_to_cpu(cmsg->raid_slot));
+	pr_info("%s:%d Sending kobject change with %s and %s\n", __func__, __LINE__, disk_uuid, raid_slot);
+	init_completion(&cinfo->newdisk_completion);
+	set_bit(MD_CLUSTER_WAITING_FOR_NEWDISK, &cinfo->state);
+	kobject_uevent_env(&disk_to_dev(mddev->gendisk)->kobj, KOBJ_CHANGE, envp);
+	wait_for_completion_timeout(&cinfo->newdisk_completion,
+			NEW_DEV_TIMEOUT);
+	clear_bit(MD_CLUSTER_WAITING_FOR_NEWDISK, &cinfo->state);
+}
+
+
+static void process_metadata_update(struct mddev *mddev, struct cluster_msg *msg)
+{
+	int got_lock = 0;
+	struct md_cluster_info *cinfo = mddev->cluster_info;
+	mddev->good_device_nr = le32_to_cpu(msg->raid_slot);
+
+	dlm_lock_sync(cinfo->no_new_dev_lockres, DLM_LOCK_CR);
+	wait_event(mddev->thread->wqueue,
+		   (got_lock = mddev_trylock(mddev)) ||
+		    test_bit(MD_CLUSTER_HOLDING_MUTEX_FOR_RECVD, &cinfo->state));
+	md_reload_sb(mddev, mddev->good_device_nr);
+	if (got_lock)
+		mddev_unlock(mddev);
+}
+
+static void process_remove_disk(struct mddev *mddev, struct cluster_msg *msg)
+{
+	struct md_rdev *rdev;
+
+	rcu_read_lock();
+	rdev = md_find_rdev_nr_rcu(mddev, le32_to_cpu(msg->raid_slot));
+	if (rdev) {
+		set_bit(ClusterRemove, &rdev->flags);
+		set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+		md_wakeup_thread(mddev->thread);
+	}
+	else
+		pr_warn("%s: %d Could not find disk(%d) to REMOVE\n",
+			__func__, __LINE__, le32_to_cpu(msg->raid_slot));
+	rcu_read_unlock();
+}
+
+static void process_readd_disk(struct mddev *mddev, struct cluster_msg *msg)
+{
+	struct md_rdev *rdev;
+
+	rcu_read_lock();
+	rdev = md_find_rdev_nr_rcu(mddev, le32_to_cpu(msg->raid_slot));
+	if (rdev && test_bit(Faulty, &rdev->flags))
+		clear_bit(Faulty, &rdev->flags);
+	else
+		pr_warn("%s: %d Could not find disk(%d) which is faulty",
+			__func__, __LINE__, le32_to_cpu(msg->raid_slot));
+	rcu_read_unlock();
+}
+
+static int process_recvd_msg(struct mddev *mddev, struct cluster_msg *msg)
+{
+	int ret = 0;
+
+	if (WARN(mddev->cluster_info->slot_number - 1 == le32_to_cpu(msg->slot),
+		"node %d received its own msg\n", le32_to_cpu(msg->slot)))
+		return -1;
+	switch (le32_to_cpu(msg->type)) {
+	case METADATA_UPDATED:
+		process_metadata_update(mddev, msg);
+		break;
+	case CHANGE_CAPACITY:
+		set_capacity_and_notify(mddev->gendisk, mddev->array_sectors);
+		break;
+	case RESYNCING:
+		set_bit(MD_RESYNCING_REMOTE, &mddev->recovery);
+		process_suspend_info(mddev, le32_to_cpu(msg->slot),
+				     le64_to_cpu(msg->low),
+				     le64_to_cpu(msg->high));
+		break;
+	case NEWDISK:
+		process_add_new_disk(mddev, msg);
+		break;
+	case REMOVE:
+		process_remove_disk(mddev, msg);
+		break;
+	case RE_ADD:
+		process_readd_disk(mddev, msg);
+		break;
+	case BITMAP_NEEDS_SYNC:
+		__recover_slot(mddev, le32_to_cpu(msg->slot));
+		break;
+	case BITMAP_RESIZE:
+		if (le64_to_cpu(msg->high) != mddev->pers->size(mddev, 0, 0))
+			ret = md_bitmap_resize(mddev->bitmap,
+					    le64_to_cpu(msg->high), 0, 0);
+		break;
+	default:
+		ret = -1;
+		pr_warn("%s:%d Received unknown message from %d\n",
+			__func__, __LINE__, msg->slot);
+	}
+	return ret;
+}
+
+/*
+ * thread for receiving message
+ */
+static void recv_daemon(struct md_thread *thread)
+{
+	struct md_cluster_info *cinfo = thread->mddev->cluster_info;
+	struct dlm_lock_resource *ack_lockres = cinfo->ack_lockres;
+	struct dlm_lock_resource *message_lockres = cinfo->message_lockres;
+	struct cluster_msg msg;
+	int ret;
+
+	mutex_lock(&cinfo->recv_mutex);
+	/*get CR on Message*/
+	if (dlm_lock_sync(message_lockres, DLM_LOCK_CR)) {
+		pr_err("md/raid1:failed to get CR on MESSAGE\n");
+		mutex_unlock(&cinfo->recv_mutex);
+		return;
+	}
+
+	/* read lvb and wake up thread to process this message_lockres */
+	memcpy(&msg, message_lockres->lksb.sb_lvbptr, sizeof(struct cluster_msg));
+	ret = process_recvd_msg(thread->mddev, &msg);
+	if (ret)
+		goto out;
+
+	/*release CR on ack_lockres*/
+	ret = dlm_unlock_sync(ack_lockres);
+	if (unlikely(ret != 0))
+		pr_info("unlock ack failed return %d\n", ret);
+	/*up-convert to PR on message_lockres*/
+	ret = dlm_lock_sync(message_lockres, DLM_LOCK_PR);
+	if (unlikely(ret != 0))
+		pr_info("lock PR on msg failed return %d\n", ret);
+	/*get CR on ack_lockres again*/
+	ret = dlm_lock_sync(ack_lockres, DLM_LOCK_CR);
+	if (unlikely(ret != 0))
+		pr_info("lock CR on ack failed return %d\n", ret);
+out:
+	/*release CR on message_lockres*/
+	ret = dlm_unlock_sync(message_lockres);
+	if (unlikely(ret != 0))
+		pr_info("unlock msg failed return %d\n", ret);
+	mutex_unlock(&cinfo->recv_mutex);
+}
+
+/* lock_token()
+ * Takes the lock on the TOKEN lock resource so no other
+ * node can communicate while the operation is underway.
+ */
+static int lock_token(struct md_cluster_info *cinfo)
+{
+	int error;
+
+	error = dlm_lock_sync(cinfo->token_lockres, DLM_LOCK_EX);
+	if (error) {
+		pr_err("md-cluster(%s:%d): failed to get EX on TOKEN (%d)\n",
+				__func__, __LINE__, error);
+	} else {
+		/* Lock the receive sequence */
+		mutex_lock(&cinfo->recv_mutex);
+	}
+	return error;
+}
+
+/* lock_comm()
+ * Sets the MD_CLUSTER_SEND_LOCK bit to lock the send channel.
+ */
+static int lock_comm(struct md_cluster_info *cinfo, bool mddev_locked)
+{
+	int rv, set_bit = 0;
+	struct mddev *mddev = cinfo->mddev;
+
+	/*
+	 * If resync thread run after raid1d thread, then process_metadata_update
+	 * could not continue if raid1d held reconfig_mutex (and raid1d is blocked
+	 * since another node already got EX on Token and waiting the EX of Ack),
+	 * so let resync wake up thread in case flag is set.
+	 */
+	if (mddev_locked && !test_bit(MD_CLUSTER_HOLDING_MUTEX_FOR_RECVD,
+				      &cinfo->state)) {
+		rv = test_and_set_bit_lock(MD_CLUSTER_HOLDING_MUTEX_FOR_RECVD,
+					      &cinfo->state);
+		WARN_ON_ONCE(rv);
+		md_wakeup_thread(mddev->thread);
+		set_bit = 1;
+	}
+
+	wait_event(cinfo->wait,
+		   !test_and_set_bit(MD_CLUSTER_SEND_LOCK, &cinfo->state));
+	rv = lock_token(cinfo);
+	if (set_bit)
+		clear_bit_unlock(MD_CLUSTER_HOLDING_MUTEX_FOR_RECVD, &cinfo->state);
+	return rv;
+}
+
+static void unlock_comm(struct md_cluster_info *cinfo)
+{
+	WARN_ON(cinfo->token_lockres->mode != DLM_LOCK_EX);
+	mutex_unlock(&cinfo->recv_mutex);
+	dlm_unlock_sync(cinfo->token_lockres);
+	clear_bit(MD_CLUSTER_SEND_LOCK, &cinfo->state);
+	wake_up(&cinfo->wait);
+}
+
+/* __sendmsg()
+ * This function performs the actual sending of the message. This function is
+ * usually called after performing the encompassing operation
+ * The function:
+ * 1. Grabs the message lockresource in EX mode
+ * 2. Copies the message to the message LVB
+ * 3. Downconverts message lockresource to CW
+ * 4. Upconverts ack lock resource from CR to EX. This forces the BAST on other nodes
+ *    and the other nodes read the message. The thread will wait here until all other
+ *    nodes have released ack lock resource.
+ * 5. Downconvert ack lockresource to CR
+ */
+static int __sendmsg(struct md_cluster_info *cinfo, struct cluster_msg *cmsg)
+{
+	int error;
+	int slot = cinfo->slot_number - 1;
+
+	cmsg->slot = cpu_to_le32(slot);
+	/*get EX on Message*/
+	error = dlm_lock_sync(cinfo->message_lockres, DLM_LOCK_EX);
+	if (error) {
+		pr_err("md-cluster: failed to get EX on MESSAGE (%d)\n", error);
+		goto failed_message;
+	}
+
+	memcpy(cinfo->message_lockres->lksb.sb_lvbptr, (void *)cmsg,
+			sizeof(struct cluster_msg));
+	/*down-convert EX to CW on Message*/
+	error = dlm_lock_sync(cinfo->message_lockres, DLM_LOCK_CW);
+	if (error) {
+		pr_err("md-cluster: failed to convert EX to CW on MESSAGE(%d)\n",
+				error);
+		goto failed_ack;
+	}
+
+	/*up-convert CR to EX on Ack*/
+	error = dlm_lock_sync(cinfo->ack_lockres, DLM_LOCK_EX);
+	if (error) {
+		pr_err("md-cluster: failed to convert CR to EX on ACK(%d)\n",
+				error);
+		goto failed_ack;
+	}
+
+	/*down-convert EX to CR on Ack*/
+	error = dlm_lock_sync(cinfo->ack_lockres, DLM_LOCK_CR);
+	if (error) {
+		pr_err("md-cluster: failed to convert EX to CR on ACK(%d)\n",
+				error);
+		goto failed_ack;
+	}
+
+failed_ack:
+	error = dlm_unlock_sync(cinfo->message_lockres);
+	if (unlikely(error != 0)) {
+		pr_err("md-cluster: failed convert to NL on MESSAGE(%d)\n",
+			error);
+		/* in case the message can't be released due to some reason */
+		goto failed_ack;
+	}
+failed_message:
+	return error;
+}
+
+static int sendmsg(struct md_cluster_info *cinfo, struct cluster_msg *cmsg,
+		   bool mddev_locked)
+{
+	int ret;
+
+	ret = lock_comm(cinfo, mddev_locked);
+	if (!ret) {
+		ret = __sendmsg(cinfo, cmsg);
+		unlock_comm(cinfo);
+	}
+	return ret;
+}
+
+static int gather_all_resync_info(struct mddev *mddev, int total_slots)
+{
+	struct md_cluster_info *cinfo = mddev->cluster_info;
+	int i, ret = 0;
+	struct dlm_lock_resource *bm_lockres;
+	char str[64];
+	sector_t lo, hi;
+
+
+	for (i = 0; i < total_slots; i++) {
+		memset(str, '\0', 64);
+		snprintf(str, 64, "bitmap%04d", i);
+		bm_lockres = lockres_init(mddev, str, NULL, 1);
+		if (!bm_lockres)
+			return -ENOMEM;
+		if (i == (cinfo->slot_number - 1)) {
+			lockres_free(bm_lockres);
+			continue;
+		}
+
+		bm_lockres->flags |= DLM_LKF_NOQUEUE;
+		ret = dlm_lock_sync(bm_lockres, DLM_LOCK_PW);
+		if (ret == -EAGAIN) {
+			if (read_resync_info(mddev, bm_lockres)) {
+				pr_info("%s:%d Resync[%llu..%llu] in progress on %d\n",
+						__func__, __LINE__,
+					(unsigned long long) cinfo->suspend_lo,
+					(unsigned long long) cinfo->suspend_hi,
+					i);
+				cinfo->suspend_from = i;
+			}
+			ret = 0;
+			lockres_free(bm_lockres);
+			continue;
+		}
+		if (ret) {
+			lockres_free(bm_lockres);
+			goto out;
+		}
+
+		/* Read the disk bitmap sb and check if it needs recovery */
+		ret = md_bitmap_copy_from_slot(mddev, i, &lo, &hi, false);
+		if (ret) {
+			pr_warn("md-cluster: Could not gather bitmaps from slot %d", i);
+			lockres_free(bm_lockres);
+			continue;
+		}
+		if ((hi > 0) && (lo < mddev->recovery_cp)) {
+			set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+			mddev->recovery_cp = lo;
+			md_check_recovery(mddev);
+		}
+
+		lockres_free(bm_lockres);
+	}
+out:
+	return ret;
+}
+
+static int join(struct mddev *mddev, int nodes)
+{
+	struct md_cluster_info *cinfo;
+	int ret, ops_rv;
+	char str[64];
+
+	cinfo = kzalloc(sizeof(struct md_cluster_info), GFP_KERNEL);
+	if (!cinfo)
+		return -ENOMEM;
+
+	INIT_LIST_HEAD(&cinfo->suspend_list);
+	spin_lock_init(&cinfo->suspend_lock);
+	init_completion(&cinfo->completion);
+	set_bit(MD_CLUSTER_BEGIN_JOIN_CLUSTER, &cinfo->state);
+	init_waitqueue_head(&cinfo->wait);
+	mutex_init(&cinfo->recv_mutex);
+
+	mddev->cluster_info = cinfo;
+	cinfo->mddev = mddev;
+
+	memset(str, 0, 64);
+	sprintf(str, "%pU", mddev->uuid);
+	ret = dlm_new_lockspace(str, mddev->bitmap_info.cluster_name,
+				0, LVB_SIZE, &md_ls_ops, mddev,
+				&ops_rv, &cinfo->lockspace);
+	if (ret)
+		goto err;
+	wait_for_completion(&cinfo->completion);
+	if (nodes < cinfo->slot_number) {
+		pr_err("md-cluster: Slot allotted(%d) is greater than available slots(%d).",
+			cinfo->slot_number, nodes);
+		ret = -ERANGE;
+		goto err;
+	}
+	/* Initiate the communication resources */
+	ret = -ENOMEM;
+	cinfo->recv_thread = md_register_thread(recv_daemon, mddev, "cluster_recv");
+	if (!cinfo->recv_thread) {
+		pr_err("md-cluster: cannot allocate memory for recv_thread!\n");
+		goto err;
+	}
+	cinfo->message_lockres = lockres_init(mddev, "message", NULL, 1);
+	if (!cinfo->message_lockres)
+		goto err;
+	cinfo->token_lockres = lockres_init(mddev, "token", NULL, 0);
+	if (!cinfo->token_lockres)
+		goto err;
+	cinfo->no_new_dev_lockres = lockres_init(mddev, "no-new-dev", NULL, 0);
+	if (!cinfo->no_new_dev_lockres)
+		goto err;
+
+	ret = dlm_lock_sync(cinfo->token_lockres, DLM_LOCK_EX);
+	if (ret) {
+		ret = -EAGAIN;
+		pr_err("md-cluster: can't join cluster to avoid lock issue\n");
+		goto err;
+	}
+	cinfo->ack_lockres = lockres_init(mddev, "ack", ack_bast, 0);
+	if (!cinfo->ack_lockres) {
+		ret = -ENOMEM;
+		goto err;
+	}
+	/* get sync CR lock on ACK. */
+	if (dlm_lock_sync(cinfo->ack_lockres, DLM_LOCK_CR))
+		pr_err("md-cluster: failed to get a sync CR lock on ACK!(%d)\n",
+				ret);
+	dlm_unlock_sync(cinfo->token_lockres);
+	/* get sync CR lock on no-new-dev. */
+	if (dlm_lock_sync(cinfo->no_new_dev_lockres, DLM_LOCK_CR))
+		pr_err("md-cluster: failed to get a sync CR lock on no-new-dev!(%d)\n", ret);
+
+
+	pr_info("md-cluster: Joined cluster %s slot %d\n", str, cinfo->slot_number);
+	snprintf(str, 64, "bitmap%04d", cinfo->slot_number - 1);
+	cinfo->bitmap_lockres = lockres_init(mddev, str, NULL, 1);
+	if (!cinfo->bitmap_lockres) {
+		ret = -ENOMEM;
+		goto err;
+	}
+	if (dlm_lock_sync(cinfo->bitmap_lockres, DLM_LOCK_PW)) {
+		pr_err("Failed to get bitmap lock\n");
+		ret = -EINVAL;
+		goto err;
+	}
+
+	cinfo->resync_lockres = lockres_init(mddev, "resync", NULL, 0);
+	if (!cinfo->resync_lockres) {
+		ret = -ENOMEM;
+		goto err;
+	}
+
+	return 0;
+err:
+	set_bit(MD_CLUSTER_HOLDING_MUTEX_FOR_RECVD, &cinfo->state);
+	md_unregister_thread(&cinfo->recovery_thread);
+	md_unregister_thread(&cinfo->recv_thread);
+	lockres_free(cinfo->message_lockres);
+	lockres_free(cinfo->token_lockres);
+	lockres_free(cinfo->ack_lockres);
+	lockres_free(cinfo->no_new_dev_lockres);
+	lockres_free(cinfo->resync_lockres);
+	lockres_free(cinfo->bitmap_lockres);
+	if (cinfo->lockspace)
+		dlm_release_lockspace(cinfo->lockspace, 2);
+	mddev->cluster_info = NULL;
+	kfree(cinfo);
+	return ret;
+}
+
+static void load_bitmaps(struct mddev *mddev, int total_slots)
+{
+	struct md_cluster_info *cinfo = mddev->cluster_info;
+
+	/* load all the node's bitmap info for resync */
+	if (gather_all_resync_info(mddev, total_slots))
+		pr_err("md-cluster: failed to gather all resyn infos\n");
+	set_bit(MD_CLUSTER_ALREADY_IN_CLUSTER, &cinfo->state);
+	/* wake up recv thread in case something need to be handled */
+	if (test_and_clear_bit(MD_CLUSTER_PENDING_RECV_EVENT, &cinfo->state))
+		md_wakeup_thread(cinfo->recv_thread);
+}
+
+static void resync_bitmap(struct mddev *mddev)
+{
+	struct md_cluster_info *cinfo = mddev->cluster_info;
+	struct cluster_msg cmsg = {0};
+	int err;
+
+	cmsg.type = cpu_to_le32(BITMAP_NEEDS_SYNC);
+	err = sendmsg(cinfo, &cmsg, 1);
+	if (err)
+		pr_err("%s:%d: failed to send BITMAP_NEEDS_SYNC message (%d)\n",
+			__func__, __LINE__, err);
+}
+
+static void unlock_all_bitmaps(struct mddev *mddev);
+static int leave(struct mddev *mddev)
+{
+	struct md_cluster_info *cinfo = mddev->cluster_info;
+
+	if (!cinfo)
+		return 0;
+
+	/*
+	 * BITMAP_NEEDS_SYNC message should be sent when node
+	 * is leaving the cluster with dirty bitmap, also we
+	 * can only deliver it when dlm connection is available.
+	 *
+	 * Also, we should send BITMAP_NEEDS_SYNC message in
+	 * case reshaping is interrupted.
+	 */
+	if ((cinfo->slot_number > 0 && mddev->recovery_cp != MaxSector) ||
+	    (mddev->reshape_position != MaxSector &&
+	     test_bit(MD_CLOSING, &mddev->flags)))
+		resync_bitmap(mddev);
+
+	set_bit(MD_CLUSTER_HOLDING_MUTEX_FOR_RECVD, &cinfo->state);
+	md_unregister_thread(&cinfo->recovery_thread);
+	md_unregister_thread(&cinfo->recv_thread);
+	lockres_free(cinfo->message_lockres);
+	lockres_free(cinfo->token_lockres);
+	lockres_free(cinfo->ack_lockres);
+	lockres_free(cinfo->no_new_dev_lockres);
+	lockres_free(cinfo->resync_lockres);
+	lockres_free(cinfo->bitmap_lockres);
+	unlock_all_bitmaps(mddev);
+	dlm_release_lockspace(cinfo->lockspace, 2);
+	kfree(cinfo);
+	return 0;
+}
+
+/* slot_number(): Returns the MD slot number to use
+ * DLM starts the slot numbers from 1, wheras cluster-md
+ * wants the number to be from zero, so we deduct one
+ */
+static int slot_number(struct mddev *mddev)
+{
+	struct md_cluster_info *cinfo = mddev->cluster_info;
+
+	return cinfo->slot_number - 1;
+}
+
+/*
+ * Check if the communication is already locked, else lock the communication
+ * channel.
+ * If it is already locked, token is in EX mode, and hence lock_token()
+ * should not be called.
+ */
+static int metadata_update_start(struct mddev *mddev)
+{
+	struct md_cluster_info *cinfo = mddev->cluster_info;
+	int ret;
+
+	/*
+	 * metadata_update_start is always called with the protection of
+	 * reconfig_mutex, so set WAITING_FOR_TOKEN here.
+	 */
+	ret = test_and_set_bit_lock(MD_CLUSTER_HOLDING_MUTEX_FOR_RECVD,
+				    &cinfo->state);
+	WARN_ON_ONCE(ret);
+	md_wakeup_thread(mddev->thread);
+
+	wait_event(cinfo->wait,
+		   !test_and_set_bit(MD_CLUSTER_SEND_LOCK, &cinfo->state) ||
+		   test_and_clear_bit(MD_CLUSTER_SEND_LOCKED_ALREADY, &cinfo->state));
+
+	/* If token is already locked, return 0 */
+	if (cinfo->token_lockres->mode == DLM_LOCK_EX) {
+		clear_bit_unlock(MD_CLUSTER_HOLDING_MUTEX_FOR_RECVD, &cinfo->state);
+		return 0;
+	}
+
+	ret = lock_token(cinfo);
+	clear_bit_unlock(MD_CLUSTER_HOLDING_MUTEX_FOR_RECVD, &cinfo->state);
+	return ret;
+}
+
+static int metadata_update_finish(struct mddev *mddev)
+{
+	struct md_cluster_info *cinfo = mddev->cluster_info;
+	struct cluster_msg cmsg;
+	struct md_rdev *rdev;
+	int ret = 0;
+	int raid_slot = -1;
+
+	memset(&cmsg, 0, sizeof(cmsg));
+	cmsg.type = cpu_to_le32(METADATA_UPDATED);
+	/* Pick up a good active device number to send.
+	 */
+	rdev_for_each(rdev, mddev)
+		if (rdev->raid_disk > -1 && !test_bit(Faulty, &rdev->flags)) {
+			raid_slot = rdev->desc_nr;
+			break;
+		}
+	if (raid_slot >= 0) {
+		cmsg.raid_slot = cpu_to_le32(raid_slot);
+		ret = __sendmsg(cinfo, &cmsg);
+	} else
+		pr_warn("md-cluster: No good device id found to send\n");
+	clear_bit(MD_CLUSTER_SEND_LOCKED_ALREADY, &cinfo->state);
+	unlock_comm(cinfo);
+	return ret;
+}
+
+static void metadata_update_cancel(struct mddev *mddev)
+{
+	struct md_cluster_info *cinfo = mddev->cluster_info;
+	clear_bit(MD_CLUSTER_SEND_LOCKED_ALREADY, &cinfo->state);
+	unlock_comm(cinfo);
+}
+
+static int update_bitmap_size(struct mddev *mddev, sector_t size)
+{
+	struct md_cluster_info *cinfo = mddev->cluster_info;
+	struct cluster_msg cmsg = {0};
+	int ret;
+
+	cmsg.type = cpu_to_le32(BITMAP_RESIZE);
+	cmsg.high = cpu_to_le64(size);
+	ret = sendmsg(cinfo, &cmsg, 0);
+	if (ret)
+		pr_err("%s:%d: failed to send BITMAP_RESIZE message (%d)\n",
+			__func__, __LINE__, ret);
+	return ret;
+}
+
+static int resize_bitmaps(struct mddev *mddev, sector_t newsize, sector_t oldsize)
+{
+	struct bitmap_counts *counts;
+	char str[64];
+	struct dlm_lock_resource *bm_lockres;
+	struct bitmap *bitmap = mddev->bitmap;
+	unsigned long my_pages = bitmap->counts.pages;
+	int i, rv;
+
+	/*
+	 * We need to ensure all the nodes can grow to a larger
+	 * bitmap size before make the reshaping.
+	 */
+	rv = update_bitmap_size(mddev, newsize);
+	if (rv)
+		return rv;
+
+	for (i = 0; i < mddev->bitmap_info.nodes; i++) {
+		if (i == md_cluster_ops->slot_number(mddev))
+			continue;
+
+		bitmap = get_bitmap_from_slot(mddev, i);
+		if (IS_ERR(bitmap)) {
+			pr_err("can't get bitmap from slot %d\n", i);
+			bitmap = NULL;
+			goto out;
+		}
+		counts = &bitmap->counts;
+
+		/*
+		 * If we can hold the bitmap lock of one node then
+		 * the slot is not occupied, update the pages.
+		 */
+		snprintf(str, 64, "bitmap%04d", i);
+		bm_lockres = lockres_init(mddev, str, NULL, 1);
+		if (!bm_lockres) {
+			pr_err("Cannot initialize %s lock\n", str);
+			goto out;
+		}
+		bm_lockres->flags |= DLM_LKF_NOQUEUE;
+		rv = dlm_lock_sync(bm_lockres, DLM_LOCK_PW);
+		if (!rv)
+			counts->pages = my_pages;
+		lockres_free(bm_lockres);
+
+		if (my_pages != counts->pages)
+			/*
+			 * Let's revert the bitmap size if one node
+			 * can't resize bitmap
+			 */
+			goto out;
+		md_bitmap_free(bitmap);
+	}
+
+	return 0;
+out:
+	md_bitmap_free(bitmap);
+	update_bitmap_size(mddev, oldsize);
+	return -1;
+}
+
+/*
+ * return 0 if all the bitmaps have the same sync_size
+ */
+static int cluster_check_sync_size(struct mddev *mddev)
+{
+	int i, rv;
+	bitmap_super_t *sb;
+	unsigned long my_sync_size, sync_size = 0;
+	int node_num = mddev->bitmap_info.nodes;
+	int current_slot = md_cluster_ops->slot_number(mddev);
+	struct bitmap *bitmap = mddev->bitmap;
+	char str[64];
+	struct dlm_lock_resource *bm_lockres;
+
+	sb = kmap_atomic(bitmap->storage.sb_page);
+	my_sync_size = sb->sync_size;
+	kunmap_atomic(sb);
+
+	for (i = 0; i < node_num; i++) {
+		if (i == current_slot)
+			continue;
+
+		bitmap = get_bitmap_from_slot(mddev, i);
+		if (IS_ERR(bitmap)) {
+			pr_err("can't get bitmap from slot %d\n", i);
+			return -1;
+		}
+
+		/*
+		 * If we can hold the bitmap lock of one node then
+		 * the slot is not occupied, update the sb.
+		 */
+		snprintf(str, 64, "bitmap%04d", i);
+		bm_lockres = lockres_init(mddev, str, NULL, 1);
+		if (!bm_lockres) {
+			pr_err("md-cluster: Cannot initialize %s\n", str);
+			md_bitmap_free(bitmap);
+			return -1;
+		}
+		bm_lockres->flags |= DLM_LKF_NOQUEUE;
+		rv = dlm_lock_sync(bm_lockres, DLM_LOCK_PW);
+		if (!rv)
+			md_bitmap_update_sb(bitmap);
+		lockres_free(bm_lockres);
+
+		sb = kmap_atomic(bitmap->storage.sb_page);
+		if (sync_size == 0)
+			sync_size = sb->sync_size;
+		else if (sync_size != sb->sync_size) {
+			kunmap_atomic(sb);
+			md_bitmap_free(bitmap);
+			return -1;
+		}
+		kunmap_atomic(sb);
+		md_bitmap_free(bitmap);
+	}
+
+	return (my_sync_size == sync_size) ? 0 : -1;
+}
+
+/*
+ * Update the size for cluster raid is a little more complex, we perform it
+ * by the steps:
+ * 1. hold token lock and update superblock in initiator node.
+ * 2. send METADATA_UPDATED msg to other nodes.
+ * 3. The initiator node continues to check each bitmap's sync_size, if all
+ *    bitmaps have the same value of sync_size, then we can set capacity and
+ *    let other nodes to perform it. If one node can't update sync_size
+ *    accordingly, we need to revert to previous value.
+ */
+static void update_size(struct mddev *mddev, sector_t old_dev_sectors)
+{
+	struct md_cluster_info *cinfo = mddev->cluster_info;
+	struct cluster_msg cmsg;
+	struct md_rdev *rdev;
+	int ret = 0;
+	int raid_slot = -1;
+
+	md_update_sb(mddev, 1);
+	if (lock_comm(cinfo, 1)) {
+		pr_err("%s: lock_comm failed\n", __func__);
+		return;
+	}
+
+	memset(&cmsg, 0, sizeof(cmsg));
+	cmsg.type = cpu_to_le32(METADATA_UPDATED);
+	rdev_for_each(rdev, mddev)
+		if (rdev->raid_disk >= 0 && !test_bit(Faulty, &rdev->flags)) {
+			raid_slot = rdev->desc_nr;
+			break;
+		}
+	if (raid_slot >= 0) {
+		cmsg.raid_slot = cpu_to_le32(raid_slot);
+		/*
+		 * We can only change capiticy after all the nodes can do it,
+		 * so need to wait after other nodes already received the msg
+		 * and handled the change
+		 */
+		ret = __sendmsg(cinfo, &cmsg);
+		if (ret) {
+			pr_err("%s:%d: failed to send METADATA_UPDATED msg\n",
+			       __func__, __LINE__);
+			unlock_comm(cinfo);
+			return;
+		}
+	} else {
+		pr_err("md-cluster: No good device id found to send\n");
+		unlock_comm(cinfo);
+		return;
+	}
+
+	/*
+	 * check the sync_size from other node's bitmap, if sync_size
+	 * have already updated in other nodes as expected, send an
+	 * empty metadata msg to permit the change of capacity
+	 */
+	if (cluster_check_sync_size(mddev) == 0) {
+		memset(&cmsg, 0, sizeof(cmsg));
+		cmsg.type = cpu_to_le32(CHANGE_CAPACITY);
+		ret = __sendmsg(cinfo, &cmsg);
+		if (ret)
+			pr_err("%s:%d: failed to send CHANGE_CAPACITY msg\n",
+			       __func__, __LINE__);
+		set_capacity_and_notify(mddev->gendisk, mddev->array_sectors);
+	} else {
+		/* revert to previous sectors */
+		ret = mddev->pers->resize(mddev, old_dev_sectors);
+		ret = __sendmsg(cinfo, &cmsg);
+		if (ret)
+			pr_err("%s:%d: failed to send METADATA_UPDATED msg\n",
+			       __func__, __LINE__);
+	}
+	unlock_comm(cinfo);
+}
+
+static int resync_start(struct mddev *mddev)
+{
+	struct md_cluster_info *cinfo = mddev->cluster_info;
+	return dlm_lock_sync_interruptible(cinfo->resync_lockres, DLM_LOCK_EX, mddev);
+}
+
+static void resync_info_get(struct mddev *mddev, sector_t *lo, sector_t *hi)
+{
+	struct md_cluster_info *cinfo = mddev->cluster_info;
+
+	spin_lock_irq(&cinfo->suspend_lock);
+	*lo = cinfo->suspend_lo;
+	*hi = cinfo->suspend_hi;
+	spin_unlock_irq(&cinfo->suspend_lock);
+}
+
+static int resync_info_update(struct mddev *mddev, sector_t lo, sector_t hi)
+{
+	struct md_cluster_info *cinfo = mddev->cluster_info;
+	struct resync_info ri;
+	struct cluster_msg cmsg = {0};
+
+	/* do not send zero again, if we have sent before */
+	if (hi == 0) {
+		memcpy(&ri, cinfo->bitmap_lockres->lksb.sb_lvbptr, sizeof(struct resync_info));
+		if (le64_to_cpu(ri.hi) == 0)
+			return 0;
+	}
+
+	add_resync_info(cinfo->bitmap_lockres, lo, hi);
+	/* Re-acquire the lock to refresh LVB */
+	dlm_lock_sync(cinfo->bitmap_lockres, DLM_LOCK_PW);
+	cmsg.type = cpu_to_le32(RESYNCING);
+	cmsg.low = cpu_to_le64(lo);
+	cmsg.high = cpu_to_le64(hi);
+
+	/*
+	 * mddev_lock is held if resync_info_update is called from
+	 * resync_finish (md_reap_sync_thread -> resync_finish)
+	 */
+	if (lo == 0 && hi == 0)
+		return sendmsg(cinfo, &cmsg, 1);
+	else
+		return sendmsg(cinfo, &cmsg, 0);
+}
+
+static int resync_finish(struct mddev *mddev)
+{
+	struct md_cluster_info *cinfo = mddev->cluster_info;
+	int ret = 0;
+
+	clear_bit(MD_RESYNCING_REMOTE, &mddev->recovery);
+
+	/*
+	 * If resync thread is interrupted so we can't say resync is finished,
+	 * another node will launch resync thread to continue.
+	 */
+	if (!test_bit(MD_CLOSING, &mddev->flags))
+		ret = resync_info_update(mddev, 0, 0);
+	dlm_unlock_sync(cinfo->resync_lockres);
+	return ret;
+}
+
+static int area_resyncing(struct mddev *mddev, int direction,
+		sector_t lo, sector_t hi)
+{
+	struct md_cluster_info *cinfo = mddev->cluster_info;
+	int ret = 0;
+
+	if ((direction == READ) &&
+		test_bit(MD_CLUSTER_SUSPEND_READ_BALANCING, &cinfo->state))
+		return 1;
+
+	spin_lock_irq(&cinfo->suspend_lock);
+	if (hi > cinfo->suspend_lo && lo < cinfo->suspend_hi)
+		ret = 1;
+	spin_unlock_irq(&cinfo->suspend_lock);
+	return ret;
+}
+
+/* add_new_disk() - initiates a disk add
+ * However, if this fails before writing md_update_sb(),
+ * add_new_disk_cancel() must be called to release token lock
+ */
+static int add_new_disk(struct mddev *mddev, struct md_rdev *rdev)
+{
+	struct md_cluster_info *cinfo = mddev->cluster_info;
+	struct cluster_msg cmsg;
+	int ret = 0;
+	struct mdp_superblock_1 *sb = page_address(rdev->sb_page);
+	char *uuid = sb->device_uuid;
+
+	memset(&cmsg, 0, sizeof(cmsg));
+	cmsg.type = cpu_to_le32(NEWDISK);
+	memcpy(cmsg.uuid, uuid, 16);
+	cmsg.raid_slot = cpu_to_le32(rdev->desc_nr);
+	if (lock_comm(cinfo, 1))
+		return -EAGAIN;
+	ret = __sendmsg(cinfo, &cmsg);
+	if (ret) {
+		unlock_comm(cinfo);
+		return ret;
+	}
+	cinfo->no_new_dev_lockres->flags |= DLM_LKF_NOQUEUE;
+	ret = dlm_lock_sync(cinfo->no_new_dev_lockres, DLM_LOCK_EX);
+	cinfo->no_new_dev_lockres->flags &= ~DLM_LKF_NOQUEUE;
+	/* Some node does not "see" the device */
+	if (ret == -EAGAIN)
+		ret = -ENOENT;
+	if (ret)
+		unlock_comm(cinfo);
+	else {
+		dlm_lock_sync(cinfo->no_new_dev_lockres, DLM_LOCK_CR);
+		/* Since MD_CHANGE_DEVS will be set in add_bound_rdev which
+		 * will run soon after add_new_disk, the below path will be
+		 * invoked:
+		 *   md_wakeup_thread(mddev->thread)
+		 *	-> conf->thread (raid1d)
+		 *	-> md_check_recovery -> md_update_sb
+		 *	-> metadata_update_start/finish
+		 * MD_CLUSTER_SEND_LOCKED_ALREADY will be cleared eventually.
+		 *
+		 * For other failure cases, metadata_update_cancel and
+		 * add_new_disk_cancel also clear below bit as well.
+		 * */
+		set_bit(MD_CLUSTER_SEND_LOCKED_ALREADY, &cinfo->state);
+		wake_up(&cinfo->wait);
+	}
+	return ret;
+}
+
+static void add_new_disk_cancel(struct mddev *mddev)
+{
+	struct md_cluster_info *cinfo = mddev->cluster_info;
+	clear_bit(MD_CLUSTER_SEND_LOCKED_ALREADY, &cinfo->state);
+	unlock_comm(cinfo);
+}
+
+static int new_disk_ack(struct mddev *mddev, bool ack)
+{
+	struct md_cluster_info *cinfo = mddev->cluster_info;
+
+	if (!test_bit(MD_CLUSTER_WAITING_FOR_NEWDISK, &cinfo->state)) {
+		pr_warn("md-cluster(%s): Spurious cluster confirmation\n", mdname(mddev));
+		return -EINVAL;
+	}
+
+	if (ack)
+		dlm_unlock_sync(cinfo->no_new_dev_lockres);
+	complete(&cinfo->newdisk_completion);
+	return 0;
+}
+
+static int remove_disk(struct mddev *mddev, struct md_rdev *rdev)
+{
+	struct cluster_msg cmsg = {0};
+	struct md_cluster_info *cinfo = mddev->cluster_info;
+	cmsg.type = cpu_to_le32(REMOVE);
+	cmsg.raid_slot = cpu_to_le32(rdev->desc_nr);
+	return sendmsg(cinfo, &cmsg, 1);
+}
+
+static int lock_all_bitmaps(struct mddev *mddev)
+{
+	int slot, my_slot, ret, held = 1, i = 0;
+	char str[64];
+	struct md_cluster_info *cinfo = mddev->cluster_info;
+
+	cinfo->other_bitmap_lockres =
+		kcalloc(mddev->bitmap_info.nodes - 1,
+			sizeof(struct dlm_lock_resource *), GFP_KERNEL);
+	if (!cinfo->other_bitmap_lockres) {
+		pr_err("md: can't alloc mem for other bitmap locks\n");
+		return 0;
+	}
+
+	my_slot = slot_number(mddev);
+	for (slot = 0; slot < mddev->bitmap_info.nodes; slot++) {
+		if (slot == my_slot)
+			continue;
+
+		memset(str, '\0', 64);
+		snprintf(str, 64, "bitmap%04d", slot);
+		cinfo->other_bitmap_lockres[i] = lockres_init(mddev, str, NULL, 1);
+		if (!cinfo->other_bitmap_lockres[i])
+			return -ENOMEM;
+
+		cinfo->other_bitmap_lockres[i]->flags |= DLM_LKF_NOQUEUE;
+		ret = dlm_lock_sync(cinfo->other_bitmap_lockres[i], DLM_LOCK_PW);
+		if (ret)
+			held = -1;
+		i++;
+	}
+
+	return held;
+}
+
+static void unlock_all_bitmaps(struct mddev *mddev)
+{
+	struct md_cluster_info *cinfo = mddev->cluster_info;
+	int i;
+
+	/* release other node's bitmap lock if they are existed */
+	if (cinfo->other_bitmap_lockres) {
+		for (i = 0; i < mddev->bitmap_info.nodes - 1; i++) {
+			if (cinfo->other_bitmap_lockres[i]) {
+				lockres_free(cinfo->other_bitmap_lockres[i]);
+			}
+		}
+		kfree(cinfo->other_bitmap_lockres);
+		cinfo->other_bitmap_lockres = NULL;
+	}
+}
+
+static int gather_bitmaps(struct md_rdev *rdev)
+{
+	int sn, err;
+	sector_t lo, hi;
+	struct cluster_msg cmsg = {0};
+	struct mddev *mddev = rdev->mddev;
+	struct md_cluster_info *cinfo = mddev->cluster_info;
+
+	cmsg.type = cpu_to_le32(RE_ADD);
+	cmsg.raid_slot = cpu_to_le32(rdev->desc_nr);
+	err = sendmsg(cinfo, &cmsg, 1);
+	if (err)
+		goto out;
+
+	for (sn = 0; sn < mddev->bitmap_info.nodes; sn++) {
+		if (sn == (cinfo->slot_number - 1))
+			continue;
+		err = md_bitmap_copy_from_slot(mddev, sn, &lo, &hi, false);
+		if (err) {
+			pr_warn("md-cluster: Could not gather bitmaps from slot %d", sn);
+			goto out;
+		}
+		if ((hi > 0) && (lo < mddev->recovery_cp))
+			mddev->recovery_cp = lo;
+	}
+out:
+	return err;
+}
+
+static struct md_cluster_operations cluster_ops = {
+	.join   = join,
+	.leave  = leave,
+	.slot_number = slot_number,
+	.resync_start = resync_start,
+	.resync_finish = resync_finish,
+	.resync_info_update = resync_info_update,
+	.resync_info_get = resync_info_get,
+	.metadata_update_start = metadata_update_start,
+	.metadata_update_finish = metadata_update_finish,
+	.metadata_update_cancel = metadata_update_cancel,
+	.area_resyncing = area_resyncing,
+	.add_new_disk = add_new_disk,
+	.add_new_disk_cancel = add_new_disk_cancel,
+	.new_disk_ack = new_disk_ack,
+	.remove_disk = remove_disk,
+	.load_bitmaps = load_bitmaps,
+	.gather_bitmaps = gather_bitmaps,
+	.resize_bitmaps = resize_bitmaps,
+	.lock_all_bitmaps = lock_all_bitmaps,
+	.unlock_all_bitmaps = unlock_all_bitmaps,
+	.update_size = update_size,
+};
+
+static int __init cluster_init(void)
+{
+	pr_warn("md-cluster: support raid1 and raid10 (limited support)\n");
+	pr_info("Registering Cluster MD functions\n");
+	register_md_cluster_operations(&cluster_ops, THIS_MODULE);
+	return 0;
+}
+
+static void cluster_exit(void)
+{
+	unregister_md_cluster_operations();
+}
+
+module_init(cluster_init);
+module_exit(cluster_exit);
+MODULE_AUTHOR("SUSE");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Clustering support for MD");