/*
   * Copyright (C) 2003 Sistina Software

   * Copyright (C) 2004-2008 Red Hat, Inc. All rights reserved.

   *
   * This file is released under the LGPL.
   */
  
  #include <linux/init.h>
  #include <linux/slab.h>
  #include <linux/module.h>
  #include <linux/vmalloc.h>

  #include <linux/dm-io.h>
  #include <linux/dm-dirty-log.h>

  #include <linux/device-mapper.h>

  #define DM_MSG_PREFIX "dirty region log"

  static LIST_HEAD(_log_types);
  static DEFINE_SPINLOCK(_lock);

  static struct dm_dirty_log_type *__find_dirty_log_type(const char *name)

  {

  	struct dm_dirty_log_type *log_type;

  
  	list_for_each_entry(log_type, &_log_types, list)

  		if (!strcmp(name, log_type->name))

  			return log_type;
  
  	return NULL;
  }

  static struct dm_dirty_log_type *_get_dirty_log_type(const char *name)

  {

  	struct dm_dirty_log_type *log_type;

  
  	spin_lock(&_lock);

  
  	log_type = __find_dirty_log_type(name);

  	if (log_type && !try_module_get(log_type->module))

  		log_type = NULL;

  
  	spin_unlock(&_lock);

  
  	return log_type;

  }

  /*
   * get_type
   * @type_name
   *

   * Attempt to retrieve the dm_dirty_log_type by name.  If not already

   * available, attempt to load the appropriate module.
   *
   * Log modules are named "dm-log-" followed by the 'type_name'.
   * Modules may contain multiple types.
   * This function will first try the module "dm-log-<type_name>",
   * then truncate 'type_name' on the last '-' and try again.
   *
   * For example, if type_name was "clustered-disk", it would search
   * 'dm-log-clustered-disk' then 'dm-log-clustered'.
   *
   * Returns: dirty_log_type* on success, NULL on failure
   */

  static struct dm_dirty_log_type *get_type(const char *type_name)

  {
  	char *p, *type_name_dup;

  	struct dm_dirty_log_type *log_type;

  	if (!type_name)
  		return NULL;
  
  	log_type = _get_dirty_log_type(type_name);
  	if (log_type)

  		return log_type;

  
  	type_name_dup = kstrdup(type_name, GFP_KERNEL);
  	if (!type_name_dup) {
  		DMWARN("No memory left to attempt log module load for \"%s\"",
  		       type_name);
  		return NULL;
  	}
  
  	while (request_module("dm-log-%s", type_name_dup) ||

  	       !(log_type = _get_dirty_log_type(type_name))) {

  		p = strrchr(type_name_dup, '-');
  		if (!p)
  			break;
  		p[0] = '\0';
  	}

  	if (!log_type)

  		DMWARN("Module for logging type \"%s\" not found.", type_name);
  
  	kfree(type_name_dup);

  	return log_type;

  }

  static void put_type(struct dm_dirty_log_type *type)

  {

  	if (!type)
  		return;

  	spin_lock(&_lock);

  	if (!__find_dirty_log_type(type->name))

  		goto out;

  	module_put(type->module);

  
  out:

  	spin_unlock(&_lock);
  }

  int dm_dirty_log_type_register(struct dm_dirty_log_type *type)
  {

  	int r = 0;

  	spin_lock(&_lock);

  	if (!__find_dirty_log_type(type->name))

  		list_add(&type->list, &_log_types);
  	else

  		r = -EEXIST;

  	spin_unlock(&_lock);

  	return r;

  }
  EXPORT_SYMBOL(dm_dirty_log_type_register);
  
  int dm_dirty_log_type_unregister(struct dm_dirty_log_type *type)
  {
  	spin_lock(&_lock);

  	if (!__find_dirty_log_type(type->name)) {

  		spin_unlock(&_lock);
  		return -EINVAL;
  	}

  	list_del(&type->list);

  
  	spin_unlock(&_lock);
  
  	return 0;
  }
  EXPORT_SYMBOL(dm_dirty_log_type_unregister);

  struct dm_dirty_log *dm_dirty_log_create(const char *type_name,

  			struct dm_target *ti,
  			int (*flush_callback_fn)(struct dm_target *ti),
  			unsigned int argc, char **argv)

  {

  	struct dm_dirty_log_type *type;
  	struct dm_dirty_log *log;

  
  	log = kmalloc(sizeof(*log), GFP_KERNEL);
  	if (!log)
  		return NULL;
  
  	type = get_type(type_name);
  	if (!type) {
  		kfree(log);
  		return NULL;
  	}

  	log->flush_callback_fn = flush_callback_fn;

  	log->type = type;
  	if (type->ctr(log, ti, argc, argv)) {
  		kfree(log);
  		put_type(type);
  		return NULL;
  	}
  
  	return log;
  }

  EXPORT_SYMBOL(dm_dirty_log_create);

  void dm_dirty_log_destroy(struct dm_dirty_log *log)

  {
  	log->type->dtr(log);
  	put_type(log->type);
  	kfree(log);
  }

  EXPORT_SYMBOL(dm_dirty_log_destroy);

  
  /*-----------------------------------------------------------------
   * Persistent and core logs share a lot of their implementation.
   * FIXME: need a reload method to be called from a resume
   *---------------------------------------------------------------*/
  /*
   * Magic for persistent mirrors: "MiRr"
   */
  #define MIRROR_MAGIC 0x4D695272
  
  /*
   * The on-disk version of the metadata.
   */

  #define MIRROR_DISK_VERSION 2

  #define LOG_OFFSET 2

  struct log_header_disk {
  	__le32 magic;

  
  	/*
  	 * Simple, incrementing version. no backward
  	 * compatibility.
  	 */

  	__le32 version;
  	__le64 nr_regions;
  } __packed;
  
  struct log_header_core {
  	uint32_t magic;

  	uint32_t version;

  	uint64_t nr_regions;

  };
  
  struct log_c {
  	struct dm_target *ti;

  	int touched_dirtied;
  	int touched_cleaned;

  	int flush_failed;

  	uint32_t region_size;
  	unsigned int region_count;
  	region_t sync_count;
  
  	unsigned bitset_uint32_count;
  	uint32_t *clean_bits;
  	uint32_t *sync_bits;
  	uint32_t *recovering_bits;	/* FIXME: this seems excessive */
  
  	int sync_search;
  
  	/* Resync flag */
  	enum sync {
  		DEFAULTSYNC,	/* Synchronize if necessary */
  		NOSYNC,		/* Devices known to be already in sync */
  		FORCESYNC,	/* Force a sync to happen */
  	} sync;

  	struct dm_io_request io_req;

  	/*
  	 * Disk log fields
  	 */

  	int log_dev_failed;

  	int log_dev_flush_failed;

  	struct dm_dev *log_dev;

  	struct log_header_core header;

  	struct dm_io_region header_location;

  	struct log_header_disk *disk_header;

  };
  
  /*
   * The touched member needs to be updated every time we access
   * one of the bitsets.
   */

  static inline int log_test_bit(uint32_t *bs, unsigned bit)

  {

  	return test_bit_le(bit, bs) ? 1 : 0;

  }
  
  static inline void log_set_bit(struct log_c *l,
  			       uint32_t *bs, unsigned bit)
  {

  	__set_bit_le(bit, bs);

  	l->touched_cleaned = 1;

  }
  
  static inline void log_clear_bit(struct log_c *l,
  				 uint32_t *bs, unsigned bit)
  {

  	__clear_bit_le(bit, bs);

  	l->touched_dirtied = 1;

  }
  
  /*----------------------------------------------------------------
   * Header IO
   *--------------------------------------------------------------*/

  static void header_to_disk(struct log_header_core *core, struct log_header_disk *disk)

  {
  	disk->magic = cpu_to_le32(core->magic);
  	disk->version = cpu_to_le32(core->version);
  	disk->nr_regions = cpu_to_le64(core->nr_regions);
  }

  static void header_from_disk(struct log_header_core *core, struct log_header_disk *disk)

  {
  	core->magic = le32_to_cpu(disk->magic);
  	core->version = le32_to_cpu(disk->version);
  	core->nr_regions = le64_to_cpu(disk->nr_regions);
  }

  static int rw_header(struct log_c *lc, int op)

  {

  	lc->io_req.bi_op = op;
  	lc->io_req.bi_op_flags = 0;

  
  	return dm_io(&lc->io_req, 1, &lc->header_location, NULL);
  }

  static int flush_header(struct log_c *lc)
  {
  	struct dm_io_region null_location = {
  		.bdev = lc->header_location.bdev,
  		.sector = 0,
  		.count = 0,
  	};

  	lc->io_req.bi_op = REQ_OP_WRITE;

  	lc->io_req.bi_op_flags = REQ_PREFLUSH;

  
  	return dm_io(&lc->io_req, 1, &null_location, NULL);
  }

  static int read_header(struct log_c *log)
  {
  	int r;

  	r = rw_header(log, REQ_OP_READ);

  	if (r)
  		return r;
  
  	header_from_disk(&log->header, log->disk_header);
  
  	/* New log required? */
  	if (log->sync != DEFAULTSYNC || log->header.magic != MIRROR_MAGIC) {
  		log->header.magic = MIRROR_MAGIC;
  		log->header.version = MIRROR_DISK_VERSION;
  		log->header.nr_regions = 0;
  	}

  #ifdef __LITTLE_ENDIAN
  	if (log->header.version == 1)
  		log->header.version = 2;
  #endif

  	if (log->header.version != MIRROR_DISK_VERSION) {
  		DMWARN("incompatible disk log version");
  		return -EINVAL;
  	}
  
  	return 0;
  }

  static int _check_region_size(struct dm_target *ti, uint32_t region_size)
  {
  	if (region_size < 2 || region_size > ti->len)
  		return 0;
  
  	if (!is_power_of_2(region_size))
  		return 0;
  
  	return 1;
  }

  /*----------------------------------------------------------------

   * core log constructor/destructor
   *
   * argv contains region_size followed optionally by [no]sync
   *--------------------------------------------------------------*/
  #define BYTE_SHIFT 3

  static int create_log_context(struct dm_dirty_log *log, struct dm_target *ti,

  			      unsigned int argc, char **argv,
  			      struct dm_dev *dev)

  {
  	enum sync sync = DEFAULTSYNC;
  
  	struct log_c *lc;
  	uint32_t region_size;
  	unsigned int region_count;

  	size_t bitset_size, buf_size;

  	int r;

  	char dummy;

  
  	if (argc < 1 || argc > 2) {

  		DMWARN("wrong number of arguments to dirty region log");

  		return -EINVAL;
  	}
  
  	if (argc > 1) {
  		if (!strcmp(argv[1], "sync"))
  			sync = FORCESYNC;
  		else if (!strcmp(argv[1], "nosync"))
  			sync = NOSYNC;
  		else {

  			DMWARN("unrecognised sync argument to "
  			       "dirty region log: %s", argv[1]);

  			return -EINVAL;
  		}
  	}

  	if (sscanf(argv[0], "%u%c", &region_size, &dummy) != 1 ||

  	    !_check_region_size(ti, region_size)) {
  		DMWARN("invalid region size %s", argv[0]);

  		return -EINVAL;
  	}
  
  	region_count = dm_sector_div_up(ti->len, region_size);
  
  	lc = kmalloc(sizeof(*lc), GFP_KERNEL);
  	if (!lc) {
  		DMWARN("couldn't allocate core log");
  		return -ENOMEM;
  	}
  
  	lc->ti = ti;

  	lc->touched_dirtied = 0;
  	lc->touched_cleaned = 0;

  	lc->flush_failed = 0;

  	lc->region_size = region_size;
  	lc->region_count = region_count;
  	lc->sync = sync;
  
  	/*

  	 * Work out how many "unsigned long"s we need to hold the bitset.

  	 */
  	bitset_size = dm_round_up(region_count,

  				  sizeof(*lc->clean_bits) << BYTE_SHIFT);

  	bitset_size >>= BYTE_SHIFT;

  	lc->bitset_uint32_count = bitset_size / sizeof(*lc->clean_bits);

  
  	/*
  	 * Disk log?
  	 */
  	if (!dev) {
  		lc->clean_bits = vmalloc(bitset_size);
  		if (!lc->clean_bits) {
  			DMWARN("couldn't allocate clean bitset");
  			kfree(lc);
  			return -ENOMEM;
  		}
  		lc->disk_header = NULL;
  	} else {
  		lc->log_dev = dev;

  		lc->log_dev_failed = 0;

  		lc->log_dev_flush_failed = 0;

  		lc->header_location.bdev = lc->log_dev->bdev;
  		lc->header_location.sector = 0;
  
  		/*
  		 * Buffer holds both header and bitset.
  		 */

  		buf_size =
  		    dm_round_up((LOG_OFFSET << SECTOR_SHIFT) + bitset_size,
  				bdev_logical_block_size(lc->header_location.
  							    bdev));

  		if (buf_size > i_size_read(dev->bdev->bd_inode)) {

  			DMWARN("log device %s too small: need %llu bytes",
  				dev->name, (unsigned long long)buf_size);
  			kfree(lc);
  			return -EINVAL;
  		}

  		lc->header_location.count = buf_size >> SECTOR_SHIFT;

  		lc->io_req.mem.type = DM_IO_VMA;

  		lc->io_req.notify.fn = NULL;

  		lc->io_req.client = dm_io_client_create();

  		if (IS_ERR(lc->io_req.client)) {
  			r = PTR_ERR(lc->io_req.client);
  			DMWARN("couldn't allocate disk io client");
  			kfree(lc);

  			return r;

  		}

  
  		lc->disk_header = vmalloc(buf_size);
  		if (!lc->disk_header) {
  			DMWARN("couldn't allocate disk log buffer");

  			dm_io_client_destroy(lc->io_req.client);

  			kfree(lc);
  			return -ENOMEM;
  		}

  		lc->io_req.mem.ptr.vma = lc->disk_header;

  		lc->clean_bits = (void *)lc->disk_header +
  				 (LOG_OFFSET << SECTOR_SHIFT);

  	}

  	memset(lc->clean_bits, -1, bitset_size);
  
  	lc->sync_bits = vmalloc(bitset_size);
  	if (!lc->sync_bits) {
  		DMWARN("couldn't allocate sync bitset");

  		if (!dev)
  			vfree(lc->clean_bits);

  		else
  			dm_io_client_destroy(lc->io_req.client);

  		vfree(lc->disk_header);

  		kfree(lc);
  		return -ENOMEM;
  	}
  	memset(lc->sync_bits, (sync == NOSYNC) ? -1 : 0, bitset_size);
  	lc->sync_count = (sync == NOSYNC) ? region_count : 0;

  	lc->recovering_bits = vzalloc(bitset_size);

  	if (!lc->recovering_bits) {
  		DMWARN("couldn't allocate sync bitset");
  		vfree(lc->sync_bits);

  		if (!dev)
  			vfree(lc->clean_bits);

  		else
  			dm_io_client_destroy(lc->io_req.client);

  		vfree(lc->disk_header);

  		kfree(lc);
  		return -ENOMEM;
  	}

  	lc->sync_search = 0;
  	log->context = lc;

  	return 0;
  }

  static int core_ctr(struct dm_dirty_log *log, struct dm_target *ti,

  		    unsigned int argc, char **argv)
  {
  	return create_log_context(log, ti, argc, argv, NULL);
  }
  
  static void destroy_log_context(struct log_c *lc)

  {

  	vfree(lc->sync_bits);
  	vfree(lc->recovering_bits);
  	kfree(lc);
  }

  static void core_dtr(struct dm_dirty_log *log)

  {
  	struct log_c *lc = (struct log_c *) log->context;
  
  	vfree(lc->clean_bits);
  	destroy_log_context(lc);
  }

  /*----------------------------------------------------------------
   * disk log constructor/destructor
   *
   * argv contains log_device region_size followed optionally by [no]sync
   *--------------------------------------------------------------*/

  static int disk_ctr(struct dm_dirty_log *log, struct dm_target *ti,

  		    unsigned int argc, char **argv)
  {
  	int r;

  	struct dm_dev *dev;
  
  	if (argc < 2 || argc > 3) {

  		DMWARN("wrong number of arguments to disk dirty region log");

  		return -EINVAL;
  	}

  	r = dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &dev);

  	if (r)
  		return r;

  	r = create_log_context(log, ti, argc - 1, argv + 1, dev);

  	if (r) {
  		dm_put_device(ti, dev);
  		return r;
  	}

  	return 0;

  }

  static void disk_dtr(struct dm_dirty_log *log)

  {
  	struct log_c *lc = (struct log_c *) log->context;

  	dm_put_device(lc->ti, lc->log_dev);
  	vfree(lc->disk_header);

  	dm_io_client_destroy(lc->io_req.client);

  	destroy_log_context(lc);

  }

  static void fail_log_device(struct log_c *lc)
  {
  	if (lc->log_dev_failed)
  		return;
  
  	lc->log_dev_failed = 1;
  	dm_table_event(lc->ti->table);
  }

  static int disk_resume(struct dm_dirty_log *log)

  {
  	int r;
  	unsigned i;
  	struct log_c *lc = (struct log_c *) log->context;
  	size_t size = lc->bitset_uint32_count * sizeof(uint32_t);
  
  	/* read the disk header */
  	r = read_header(lc);

  	if (r) {

  		DMWARN("%s: Failed to read header on dirty region log device",

  		       lc->log_dev->name);
  		fail_log_device(lc);

  		/*
  		 * If the log device cannot be read, we must assume
  		 * all regions are out-of-sync.  If we simply return
  		 * here, the state will be uninitialized and could
  		 * lead us to return 'in-sync' status for regions
  		 * that are actually 'out-of-sync'.
  		 */
  		lc->header.nr_regions = 0;

  	}

  	/* set or clear any new bits -- device has grown */

  	if (lc->sync == NOSYNC)
  		for (i = lc->header.nr_regions; i < lc->region_count; i++)
  			/* FIXME: amazingly inefficient */
  			log_set_bit(lc, lc->clean_bits, i);
  	else
  		for (i = lc->header.nr_regions; i < lc->region_count; i++)
  			/* FIXME: amazingly inefficient */
  			log_clear_bit(lc, lc->clean_bits, i);

  	/* clear any old bits -- device has shrunk */
  	for (i = lc->region_count; i % (sizeof(*lc->clean_bits) << BYTE_SHIFT); i++)
  		log_clear_bit(lc, lc->clean_bits, i);

  	/* copy clean across to sync */
  	memcpy(lc->sync_bits, lc->clean_bits, size);

  	lc->sync_count = memweight(lc->clean_bits,
  				lc->bitset_uint32_count * sizeof(uint32_t));

  	lc->sync_search = 0;

  	/* set the correct number of regions in the header */
  	lc->header.nr_regions = lc->region_count;

  	header_to_disk(&lc->header, lc->disk_header);

  	/* write the new header */

  	r = rw_header(lc, REQ_OP_WRITE);

  	if (!r) {

  		r = flush_header(lc);

  		if (r)
  			lc->log_dev_flush_failed = 1;
  	}

  	if (r) {

  		DMWARN("%s: Failed to write header on dirty region log device",

  		       lc->log_dev->name);
  		fail_log_device(lc);
  	}
  
  	return r;

  }

  static uint32_t core_get_region_size(struct dm_dirty_log *log)

  {
  	struct log_c *lc = (struct log_c *) log->context;
  	return lc->region_size;
  }

  static int core_resume(struct dm_dirty_log *log)

  {
  	struct log_c *lc = (struct log_c *) log->context;
  	lc->sync_search = 0;
  	return 0;
  }

  static int core_is_clean(struct dm_dirty_log *log, region_t region)

  {
  	struct log_c *lc = (struct log_c *) log->context;
  	return log_test_bit(lc->clean_bits, region);
  }

  static int core_in_sync(struct dm_dirty_log *log, region_t region, int block)

  {
  	struct log_c *lc = (struct log_c *) log->context;
  	return log_test_bit(lc->sync_bits, region);
  }

  static int core_flush(struct dm_dirty_log *log)

  {
  	/* no op */
  	return 0;
  }

  static int disk_flush(struct dm_dirty_log *log)

  {

  	int r, i;
  	struct log_c *lc = log->context;

  
  	/* only write if the log has changed */

  	if (!lc->touched_cleaned && !lc->touched_dirtied)

  		return 0;

  	if (lc->touched_cleaned && log->flush_callback_fn &&
  	    log->flush_callback_fn(lc->ti)) {
  		/*
  		 * At this point it is impossible to determine which
  		 * regions are clean and which are dirty (without
  		 * re-reading the log off disk). So mark all of them
  		 * dirty.
  		 */
  		lc->flush_failed = 1;
  		for (i = 0; i < lc->region_count; i++)
  			log_clear_bit(lc, lc->clean_bits, i);
  	}

  	r = rw_header(lc, REQ_OP_WRITE);

  	if (r)
  		fail_log_device(lc);

  	else {

  		if (lc->touched_dirtied) {
  			r = flush_header(lc);

  			if (r) {
  				lc->log_dev_flush_failed = 1;

  				fail_log_device(lc);

  			} else

  				lc->touched_dirtied = 0;
  		}

  		lc->touched_cleaned = 0;
  	}

  
  	return r;
  }

  static void core_mark_region(struct dm_dirty_log *log, region_t region)

  {
  	struct log_c *lc = (struct log_c *) log->context;
  	log_clear_bit(lc, lc->clean_bits, region);
  }

  static void core_clear_region(struct dm_dirty_log *log, region_t region)

  {
  	struct log_c *lc = (struct log_c *) log->context;

  	if (likely(!lc->flush_failed))
  		log_set_bit(lc, lc->clean_bits, region);

  }

  static int core_get_resync_work(struct dm_dirty_log *log, region_t *region)

  {
  	struct log_c *lc = (struct log_c *) log->context;
  
  	if (lc->sync_search >= lc->region_count)
  		return 0;
  
  	do {

  		*region = find_next_zero_bit_le(lc->sync_bits,

  					     lc->region_count,
  					     lc->sync_search);
  		lc->sync_search = *region + 1;

  		if (*region >= lc->region_count)

  			return 0;
  
  	} while (log_test_bit(lc->recovering_bits, *region));
  
  	log_set_bit(lc, lc->recovering_bits, *region);
  	return 1;
  }

  static void core_set_region_sync(struct dm_dirty_log *log, region_t region,

  				 int in_sync)

  {
  	struct log_c *lc = (struct log_c *) log->context;
  
  	log_clear_bit(lc, lc->recovering_bits, region);

  	if (in_sync) {

  		log_set_bit(lc, lc->sync_bits, region);
                  lc->sync_count++;

          } else if (log_test_bit(lc->sync_bits, region)) {
  		lc->sync_count--;
  		log_clear_bit(lc, lc->sync_bits, region);
  	}

  }

  static region_t core_get_sync_count(struct dm_dirty_log *log)

  {
          struct log_c *lc = (struct log_c *) log->context;
  
          return lc->sync_count;
  }
  
  #define	DMEMIT_SYNC \
  	if (lc->sync != DEFAULTSYNC) \
  		DMEMIT("%ssync ", lc->sync == NOSYNC ? "no" : "")

  static int core_status(struct dm_dirty_log *log, status_type_t status,

  		       char *result, unsigned int maxlen)
  {
  	int sz = 0;
  	struct log_c *lc = log->context;
  
  	switch(status) {
  	case STATUSTYPE_INFO:

  		DMEMIT("1 %s", log->type->name);

  		break;
  
  	case STATUSTYPE_TABLE:
  		DMEMIT("%s %u %u ", log->type->name,
  		       lc->sync == DEFAULTSYNC ? 1 : 2, lc->region_size);
  		DMEMIT_SYNC;
  	}
  
  	return sz;
  }

  static int disk_status(struct dm_dirty_log *log, status_type_t status,

  		       char *result, unsigned int maxlen)
  {
  	int sz = 0;

  	struct log_c *lc = log->context;
  
  	switch(status) {
  	case STATUSTYPE_INFO:

  		DMEMIT("3 %s %s %c", log->type->name, lc->log_dev->name,

  		       lc->log_dev_flush_failed ? 'F' :
  		       lc->log_dev_failed ? 'D' :
  		       'A');

  		break;
  
  	case STATUSTYPE_TABLE:

  		DMEMIT("%s %u %s %u ", log->type->name,

  		       lc->sync == DEFAULTSYNC ? 2 : 3, lc->log_dev->name,

  		       lc->region_size);
  		DMEMIT_SYNC;
  	}
  
  	return sz;
  }

  static struct dm_dirty_log_type _core_type = {

  	.name = "core",
  	.module = THIS_MODULE,
  	.ctr = core_ctr,
  	.dtr = core_dtr,

  	.resume = core_resume,

  	.get_region_size = core_get_region_size,
  	.is_clean = core_is_clean,
  	.in_sync = core_in_sync,
  	.flush = core_flush,
  	.mark_region = core_mark_region,
  	.clear_region = core_clear_region,
  	.get_resync_work = core_get_resync_work,

  	.set_region_sync = core_set_region_sync,

  	.get_sync_count = core_get_sync_count,
  	.status = core_status,
  };

  static struct dm_dirty_log_type _disk_type = {

  	.name = "disk",
  	.module = THIS_MODULE,
  	.ctr = disk_ctr,
  	.dtr = disk_dtr,

  	.postsuspend = disk_flush,

  	.resume = disk_resume,
  	.get_region_size = core_get_region_size,
  	.is_clean = core_is_clean,
  	.in_sync = core_in_sync,
  	.flush = disk_flush,
  	.mark_region = core_mark_region,
  	.clear_region = core_clear_region,
  	.get_resync_work = core_get_resync_work,

  	.set_region_sync = core_set_region_sync,

  	.get_sync_count = core_get_sync_count,
  	.status = disk_status,
  };

  static int __init dm_dirty_log_init(void)

  {
  	int r;

  	r = dm_dirty_log_type_register(&_core_type);

  	if (r)
  		DMWARN("couldn't register core log");

  	r = dm_dirty_log_type_register(&_disk_type);

  	if (r) {
  		DMWARN("couldn't register disk type");

  		dm_dirty_log_type_unregister(&_core_type);

  	}
  
  	return r;
  }

  static void __exit dm_dirty_log_exit(void)

  {

  	dm_dirty_log_type_unregister(&_disk_type);
  	dm_dirty_log_type_unregister(&_core_type);

  }

  module_init(dm_dirty_log_init);
  module_exit(dm_dirty_log_exit);
  
  MODULE_DESCRIPTION(DM_NAME " dirty region log");
  MODULE_AUTHOR("Joe Thornber, Heinz Mauelshagen <dm-devel@redhat.com>");
  MODULE_LICENSE("GPL");