drivers/md/md-cluster.c - SHIFTPHONES/kernel/common - Gitiles

 /*
  * Copyright (C) 2015, SUSE
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2, or (at your option)
  * any later version.
  *
  */


 #include <linux/module.h>
 #include <linux/dlm.h>
 #include <linux/sched.h>
 #include "md.h"
 #include "bitmap.h"
 #include "md-cluster.h"

 #define LVB_SIZE	64

 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() */
 	struct completion completion; /* completion for synchronized locking */
 	void (*bast)(void *arg, int mode); /* blocking AST function pointer*/
 	struct mddev *mddev; /* pointing back to mddev. */
 };

 struct suspend_info {
 	int slot;
 	sector_t lo;
 	sector_t hi;
 	struct list_head list;
 };

 struct resync_info {
 	__le64 lo;
 	__le64 hi;
 };

 struct md_cluster_info {
 	/* dlm lock space and resources for clustered raid. */
 	dlm_lockspace_t *lockspace;
 	int slot_number;
 	struct completion completion;
 	struct dlm_lock_resource *sb_lock;
 	struct mutex sb_mutex;
 	struct dlm_lock_resource *bitmap_lockres;
 	struct list_head suspend_list;
 	spinlock_t suspend_lock;
 	struct md_thread *recovery_thread;
 	unsigned long recovery_map;
 };

 static void sync_ast(void *arg)
 {
 	struct dlm_lock_resource *res;

 	res = (struct dlm_lock_resource *) arg;
 	complete(&res->completion);
 }

 static int dlm_lock_sync(struct dlm_lock_resource *res, int mode)
 {
 	int ret = 0;

 	init_completion(&res->completion);
 	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_for_completion(&res->completion);
 	return res->lksb.sb_status;
 }

 static int dlm_unlock_sync(struct dlm_lock_resource *res)
 {
 	return dlm_lock_sync(res, DLM_LOCK_NL);
 }

 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;
 	res->ls = cinfo->lockspace;
 	res->mddev = mddev;
 	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;
 	}
 	strlcpy(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)
 {
 	if (!res)
 		return;

 	init_completion(&res->completion);
 	dlm_unlock(res->ls, res->lksb.sb_lkid, 0, &res->lksb, res);
 	wait_for_completion(&res->completion);

 	kfree(res->name);
 	kfree(res->lksb.sb_lvbptr);
 	kfree(res);
 }

 static char *pretty_uuid(char *dest, char *src)
 {
 	int i, len = 0;

 	for (i = 0; i < 16; i++) {
 		if (i == 4 || i == 6 || i == 8 || i == 10)
 			len += sprintf(dest + len, "-");
 		len += sprintf(dest + len, "%02x", (__u8)src[i]);
 	}
 	return dest;
 }

 static void add_resync_info(struct mddev *mddev, 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 struct suspend_info *read_resync_info(struct mddev *mddev, struct dlm_lock_resource *lockres)
 {
 	struct resync_info ri;
 	struct suspend_info *s = NULL;
 	sector_t hi = 0;

 	dlm_lock_sync(lockres, DLM_LOCK_CR);
 	memcpy(&ri, lockres->lksb.sb_lvbptr, sizeof(struct resync_info));
 	hi = le64_to_cpu(ri.hi);
 	if (ri.hi > 0) {
 		s = kzalloc(sizeof(struct suspend_info), GFP_KERNEL);
 		if (!s)
 			goto out;
 		s->hi = hi;
 		s->lo = le64_to_cpu(ri.lo);
 	}
 	dlm_unlock_sync(lockres);
 out:
 	return s;
 }

 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;
 	struct suspend_info *s, *tmp;
 	sector_t lo, hi;

 	while (cinfo->recovery_map) {
 		slot = fls64((u64)cinfo->recovery_map) - 1;

 		/* Clear suspend_area associated with the bitmap */
 		spin_lock_irq(&cinfo->suspend_lock);
 		list_for_each_entry_safe(s, tmp, &cinfo->suspend_list, list)
 			if (slot == s->slot) {
 				list_del(&s->list);
 				kfree(s);
 			}
 		spin_unlock_irq(&cinfo->suspend_lock);

 		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(bm_lockres, DLM_LOCK_PW);
 		if (ret) {
 			pr_err("md-cluster: Could not DLM lock %s: %d\n",
 					str, ret);
 			goto clear_bit;
 		}
 		ret = bitmap_copy_from_slot(mddev, slot, &lo, &hi);
 		if (ret) {
 			pr_err("md-cluster: Could not copy data from bitmap %d\n", slot);
 			goto dlm_unlock;
 		}
 		if (hi > 0) {
 			/* TODO:Wait for current resync to get over */
 			set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
 			if (lo < mddev->recovery_cp)
 				mddev->recovery_cp = lo;
 			md_check_recovery(mddev);
 		}
 dlm_unlock:
 		dlm_unlock_sync(bm_lockres);
 clear_bit:
 		clear_bit(slot, &cinfo->recovery_map);
 	}
 }

 static void recover_prep(void *arg)
 {
 }

 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);
 	set_bit(slot->slot - 1, &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_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;
 	complete(&cinfo->completion);
 }

 static const struct dlm_lockspace_ops md_ls_ops = {
 	.recover_prep = recover_prep,
 	.recover_slot = recover_slot,
 	.recover_done = recover_done,
 };

 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;
 	struct suspend_info *s;
 	char str[64];


 	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))
 			continue;

 		bm_lockres->flags |= DLM_LKF_NOQUEUE;
 		ret = dlm_lock_sync(bm_lockres, DLM_LOCK_PW);
 		if (ret == -EAGAIN) {
 			memset(bm_lockres->lksb.sb_lvbptr, '\0', LVB_SIZE);
 			s = read_resync_info(mddev, bm_lockres);
 			if (s) {
 				pr_info("%s:%d Resync[%llu..%llu] in progress on %d\n",
 						__func__, __LINE__,
 						(unsigned long long) s->lo,
 						(unsigned long long) s->hi, i);
 				spin_lock_irq(&cinfo->suspend_lock);
 				s->slot = i;
 				list_add(&s->list, &cinfo->suspend_list);
 				spin_unlock_irq(&cinfo->suspend_lock);
 			}
 			ret = 0;
 			lockres_free(bm_lockres);
 			continue;
 		}
 		if (ret)
 			goto out;
 		/* TODO: Read the disk bitmap sb and check if it needs recovery */
 		dlm_unlock_sync(bm_lockres);
 		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];

 	if (!try_module_get(THIS_MODULE))
 		return -ENOENT;

 	cinfo = kzalloc(sizeof(struct md_cluster_info), GFP_KERNEL);
 	if (!cinfo)
 		return -ENOMEM;

 	init_completion(&cinfo->completion);

 	mutex_init(&cinfo->sb_mutex);
 	mddev->cluster_info = cinfo;

 	memset(str, 0, 64);
 	pretty_uuid(str, mddev->uuid);
 	ret = dlm_new_lockspace(str, mddev->bitmap_info.cluster_name,
 				DLM_LSFL_FS, 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) greater than available slots(%d)", cinfo->slot_number - 1,
 			nodes);
 		ret = -ERANGE;
 		goto err;
 	}
 	cinfo->sb_lock = lockres_init(mddev, "cmd-super",
 					NULL, 0);
 	if (!cinfo->sb_lock) {
 		ret = -ENOMEM;
 		goto err;
 	}

 	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)
 		goto err;
 	if (dlm_lock_sync(cinfo->bitmap_lockres, DLM_LOCK_PW)) {
 		pr_err("Failed to get bitmap lock\n");
 		ret = -EINVAL;
 		goto err;
 	}

 	INIT_LIST_HEAD(&cinfo->suspend_list);
 	spin_lock_init(&cinfo->suspend_lock);

 	ret = gather_all_resync_info(mddev, nodes);
 	if (ret)
 		goto err;

 	return 0;
 err:
 	lockres_free(cinfo->bitmap_lockres);
 	lockres_free(cinfo->sb_lock);
 	if (cinfo->lockspace)
 		dlm_release_lockspace(cinfo->lockspace, 2);
 	mddev->cluster_info = NULL;
 	kfree(cinfo);
 	module_put(THIS_MODULE);
 	return ret;
 }

 static int leave(struct mddev *mddev)
 {
 	struct md_cluster_info *cinfo = mddev->cluster_info;

 	if (!cinfo)
 		return 0;
 	md_unregister_thread(&cinfo->recovery_thread);
 	lockres_free(cinfo->sb_lock);
 	lockres_free(cinfo->bitmap_lockres);
 	dlm_release_lockspace(cinfo->lockspace, 2);
 	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;
 }

 static void resync_info_update(struct mddev *mddev, sector_t lo, sector_t hi)
 {
 	struct md_cluster_info *cinfo = mddev->cluster_info;

 	add_resync_info(mddev, cinfo->bitmap_lockres, lo, hi);
 	/* Re-acquire the lock to refresh LVB */
 	dlm_lock_sync(cinfo->bitmap_lockres, DLM_LOCK_PW);
 }

 static struct md_cluster_operations cluster_ops = {
 	.join   = join,
 	.leave  = leave,
 	.slot_number = slot_number,
 	.resync_info_update = resync_info_update,
 };

 static int __init cluster_init(void)
 {
 	pr_warn("md-cluster: EXPERIMENTAL. Use with caution\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_LICENSE("GPL");
 MODULE_DESCRIPTION("Clustering support for MD");
	/*
	* Copyright (C) 2015, SUSE
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2, or (at your option)
	* any later version.
	*
	*/


	#include <linux/module.h>
	#include <linux/dlm.h>
	#include <linux/sched.h>
	#include "md.h"
	#include "bitmap.h"
	#include "md-cluster.h"

	#define LVB_SIZE 64

	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() */
	struct completion completion; /* completion for synchronized locking */
	void (bast)(void arg, int mode); /* blocking AST function pointer*/
	struct mddev mddev; / pointing back to mddev. */
	};

	struct suspend_info {
	int slot;
	sector_t lo;
	sector_t hi;
	struct list_head list;
	};

	struct resync_info {
	__le64 lo;
	__le64 hi;
	};

	struct md_cluster_info {
	/* dlm lock space and resources for clustered raid. */
	dlm_lockspace_t *lockspace;
	int slot_number;
	struct completion completion;
	struct dlm_lock_resource *sb_lock;
	struct mutex sb_mutex;
	struct dlm_lock_resource *bitmap_lockres;
	struct list_head suspend_list;
	spinlock_t suspend_lock;
	struct md_thread *recovery_thread;
	unsigned long recovery_map;
	};

	static void sync_ast(void *arg)
	{
	struct dlm_lock_resource *res;

	res = (struct dlm_lock_resource *) arg;
	complete(&res->completion);
	}

	static int dlm_lock_sync(struct dlm_lock_resource *res, int mode)
	{
	int ret = 0;

	init_completion(&res->completion);
	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_for_completion(&res->completion);
	return res->lksb.sb_status;
	}

	static int dlm_unlock_sync(struct dlm_lock_resource *res)
	{
	return dlm_lock_sync(res, DLM_LOCK_NL);
	}

	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;
	res->ls = cinfo->lockspace;
	res->mddev = mddev;
	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;
	}
	strlcpy(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)
	{
	if (!res)
	return;

	init_completion(&res->completion);
	dlm_unlock(res->ls, res->lksb.sb_lkid, 0, &res->lksb, res);
	wait_for_completion(&res->completion);

	kfree(res->name);
	kfree(res->lksb.sb_lvbptr);
	kfree(res);
	}

	static char pretty_uuid(char dest, char *src)
	{
	int i, len = 0;

	for (i = 0; i < 16; i++) {
	if (i == 4 \|\| i == 6 \|\| i == 8 \|\| i == 10)
	len += sprintf(dest + len, "-");
	len += sprintf(dest + len, "%02x", (__u8)src[i]);
	}
	return dest;
	}

	static void add_resync_info(struct mddev mddev, 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 struct suspend_info read_resync_info(struct mddev mddev, struct dlm_lock_resource *lockres)
	{
	struct resync_info ri;
	struct suspend_info *s = NULL;
	sector_t hi = 0;

	dlm_lock_sync(lockres, DLM_LOCK_CR);
	memcpy(&ri, lockres->lksb.sb_lvbptr, sizeof(struct resync_info));
	hi = le64_to_cpu(ri.hi);
	if (ri.hi > 0) {
	s = kzalloc(sizeof(struct suspend_info), GFP_KERNEL);
	if (!s)
	goto out;
	s->hi = hi;
	s->lo = le64_to_cpu(ri.lo);
	}
	dlm_unlock_sync(lockres);
	out:
	return s;
	}

	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;
	struct suspend_info s, tmp;
	sector_t lo, hi;

	while (cinfo->recovery_map) {
	slot = fls64((u64)cinfo->recovery_map) - 1;

	/* Clear suspend_area associated with the bitmap */
	spin_lock_irq(&cinfo->suspend_lock);
	list_for_each_entry_safe(s, tmp, &cinfo->suspend_list, list)
	if (slot == s->slot) {
	list_del(&s->list);
	kfree(s);
	}
	spin_unlock_irq(&cinfo->suspend_lock);

	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(bm_lockres, DLM_LOCK_PW);
	if (ret) {
	pr_err("md-cluster: Could not DLM lock %s: %d\n",
	str, ret);
	goto clear_bit;
	}
	ret = bitmap_copy_from_slot(mddev, slot, &lo, &hi);
	if (ret) {
	pr_err("md-cluster: Could not copy data from bitmap %d\n", slot);
	goto dlm_unlock;
	}
	if (hi > 0) {
	/* TODO:Wait for current resync to get over */
	set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
	if (lo < mddev->recovery_cp)
	mddev->recovery_cp = lo;
	md_check_recovery(mddev);
	}
	dlm_unlock:
	dlm_unlock_sync(bm_lockres);
	clear_bit:
	clear_bit(slot, &cinfo->recovery_map);
	}
	}

	static void recover_prep(void *arg)
	{
	}

	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);
	set_bit(slot->slot - 1, &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_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;
	complete(&cinfo->completion);
	}

	static const struct dlm_lockspace_ops md_ls_ops = {
	.recover_prep = recover_prep,
	.recover_slot = recover_slot,
	.recover_done = recover_done,
	};

	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;
	struct suspend_info *s;
	char str[64];


	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))
	continue;

	bm_lockres->flags \|= DLM_LKF_NOQUEUE;
	ret = dlm_lock_sync(bm_lockres, DLM_LOCK_PW);
	if (ret == -EAGAIN) {
	memset(bm_lockres->lksb.sb_lvbptr, '\0', LVB_SIZE);
	s = read_resync_info(mddev, bm_lockres);
	if (s) {
	pr_info("%s:%d Resync[%llu..%llu] in progress on %d\n",
	__func__, __LINE__,
	(unsigned long long) s->lo,
	(unsigned long long) s->hi, i);
	spin_lock_irq(&cinfo->suspend_lock);
	s->slot = i;
	list_add(&s->list, &cinfo->suspend_list);
	spin_unlock_irq(&cinfo->suspend_lock);
	}
	ret = 0;
	lockres_free(bm_lockres);
	continue;
	}
	if (ret)
	goto out;
	/* TODO: Read the disk bitmap sb and check if it needs recovery */
	dlm_unlock_sync(bm_lockres);
	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];

	if (!try_module_get(THIS_MODULE))
	return -ENOENT;

	cinfo = kzalloc(sizeof(struct md_cluster_info), GFP_KERNEL);
	if (!cinfo)
	return -ENOMEM;

	init_completion(&cinfo->completion);

	mutex_init(&cinfo->sb_mutex);
	mddev->cluster_info = cinfo;

	memset(str, 0, 64);
	pretty_uuid(str, mddev->uuid);
	ret = dlm_new_lockspace(str, mddev->bitmap_info.cluster_name,
	DLM_LSFL_FS, 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) greater than available slots(%d)", cinfo->slot_number - 1,
	nodes);
	ret = -ERANGE;
	goto err;
	}
	cinfo->sb_lock = lockres_init(mddev, "cmd-super",
	NULL, 0);
	if (!cinfo->sb_lock) {
	ret = -ENOMEM;
	goto err;
	}

	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)
	goto err;
	if (dlm_lock_sync(cinfo->bitmap_lockres, DLM_LOCK_PW)) {
	pr_err("Failed to get bitmap lock\n");
	ret = -EINVAL;
	goto err;
	}

	INIT_LIST_HEAD(&cinfo->suspend_list);
	spin_lock_init(&cinfo->suspend_lock);

	ret = gather_all_resync_info(mddev, nodes);
	if (ret)
	goto err;

	return 0;
	err:
	lockres_free(cinfo->bitmap_lockres);
	lockres_free(cinfo->sb_lock);
	if (cinfo->lockspace)
	dlm_release_lockspace(cinfo->lockspace, 2);
	mddev->cluster_info = NULL;
	kfree(cinfo);
	module_put(THIS_MODULE);
	return ret;
	}

	static int leave(struct mddev *mddev)
	{
	struct md_cluster_info *cinfo = mddev->cluster_info;

	if (!cinfo)
	return 0;
	md_unregister_thread(&cinfo->recovery_thread);
	lockres_free(cinfo->sb_lock);
	lockres_free(cinfo->bitmap_lockres);
	dlm_release_lockspace(cinfo->lockspace, 2);
	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;
	}

	static void resync_info_update(struct mddev *mddev, sector_t lo, sector_t hi)
	{
	struct md_cluster_info *cinfo = mddev->cluster_info;

	add_resync_info(mddev, cinfo->bitmap_lockres, lo, hi);
	/* Re-acquire the lock to refresh LVB */
	dlm_lock_sync(cinfo->bitmap_lockres, DLM_LOCK_PW);
	}

	static struct md_cluster_operations cluster_ops = {
	.join = join,
	.leave = leave,
	.slot_number = slot_number,
	.resync_info_update = resync_info_update,
	};

	static int __init cluster_init(void)
	{
	pr_warn("md-cluster: EXPERIMENTAL. Use with caution\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_LICENSE("GPL");
	MODULE_DESCRIPTION("Clustering support for MD");