text: /*
   * Copyright (C) 2012 Red Hat, Inc.
   *
   * This file is released under the GPL.
   */
  
  #include "dm-bitset.h"
  #include "dm-transaction-manager.h"
  
  #include <linux/export.h>
  #include <linux/device-mapper.h>
  
  #define DM_MSG_PREFIX "bitset"
  #define BITS_PER_ARRAY_ENTRY 64
  
  /*----------------------------------------------------------------*/
  
  static struct dm_btree_value_type bitset_bvt = {
  	.context = NULL,
  	.size = sizeof(__le64),
  	.inc = NULL,
  	.dec = NULL,
  	.equal = NULL,
  };
  
  /*----------------------------------------------------------------*/
  
  void dm_disk_bitset_init(struct dm_transaction_manager *tm,
  			 struct dm_disk_bitset *info)
  {
  	dm_array_info_init(&info->array_info, tm, &bitset_bvt);
  	info->current_index_set = false;
  }
  EXPORT_SYMBOL_GPL(dm_disk_bitset_init);
  
  int dm_bitset_empty(struct dm_disk_bitset *info, dm_block_t *root)
  {
  	return dm_array_empty(&info->array_info, root);
  }
  EXPORT_SYMBOL_GPL(dm_bitset_empty);
  
  int dm_bitset_resize(struct dm_disk_bitset *info, dm_block_t root,
  		     uint32_t old_nr_entries, uint32_t new_nr_entries,
  		     bool default_value, dm_block_t *new_root)
  {
  	uint32_t old_blocks = dm_div_up(old_nr_entries, BITS_PER_ARRAY_ENTRY);
  	uint32_t new_blocks = dm_div_up(new_nr_entries, BITS_PER_ARRAY_ENTRY);
  	__le64 value = default_value ? cpu_to_le64(~0) : cpu_to_le64(0);
  
  	__dm_bless_for_disk(&value);
  	return dm_array_resize(&info->array_info, root, old_blocks, new_blocks,
  			       &value, new_root);
  }
  EXPORT_SYMBOL_GPL(dm_bitset_resize);
  
  int dm_bitset_del(struct dm_disk_bitset *info, dm_block_t root)
  {
  	return dm_array_del(&info->array_info, root);
  }
  EXPORT_SYMBOL_GPL(dm_bitset_del);
  
  int dm_bitset_flush(struct dm_disk_bitset *info, dm_block_t root,
  		    dm_block_t *new_root)
  {
  	int r;
  	__le64 value;
  
  	if (!info->current_index_set)
  		return 0;
  
  	value = cpu_to_le64(info->current_bits);
  
  	__dm_bless_for_disk(&value);
  	r = dm_array_set_value(&info->array_info, root, info->current_index,
  			       &value, new_root);
  	if (r)
  		return r;
  
  	info->current_index_set = false;
  	return 0;
  }
  EXPORT_SYMBOL_GPL(dm_bitset_flush);
  
  static int read_bits(struct dm_disk_bitset *info, dm_block_t root,
  		     uint32_t array_index)
  {
  	int r;
  	__le64 value;
  
  	r = dm_array_get_value(&info->array_info, root, array_index, &value);
  	if (r)
  		return r;
  
  	info->current_bits = le64_to_cpu(value);
  	info->current_index_set = true;
  	info->current_index = array_index;
  	return 0;
  }
  
  static int get_array_entry(struct dm_disk_bitset *info, dm_block_t root,
  			   uint32_t index, dm_block_t *new_root)
  {
  	int r;
  	unsigned array_index = index / BITS_PER_ARRAY_ENTRY;
  
  	if (info->current_index_set) {
  		if (info->current_index == array_index)
  			return 0;
  
  		r = dm_bitset_flush(info, root, new_root);
  		if (r)
  			return r;
  	}
  
  	return read_bits(info, root, array_index);
  }
  
  int dm_bitset_set_bit(struct dm_disk_bitset *info, dm_block_t root,
  		      uint32_t index, dm_block_t *new_root)
  {
  	int r;
  	unsigned b = index % BITS_PER_ARRAY_ENTRY;
  
  	r = get_array_entry(info, root, index, new_root);
  	if (r)
  		return r;
  
  	set_bit(b, (unsigned long *) &info->current_bits);
  	return 0;
  }
  EXPORT_SYMBOL_GPL(dm_bitset_set_bit);
  
  int dm_bitset_clear_bit(struct dm_disk_bitset *info, dm_block_t root,
  			uint32_t index, dm_block_t *new_root)
  {
  	int r;
  	unsigned b = index % BITS_PER_ARRAY_ENTRY;
  
  	r = get_array_entry(info, root, index, new_root);
  	if (r)
  		return r;
  
  	clear_bit(b, (unsigned long *) &info->current_bits);
  	return 0;
  }
  EXPORT_SYMBOL_GPL(dm_bitset_clear_bit);
  
  int dm_bitset_test_bit(struct dm_disk_bitset *info, dm_block_t root,
  		       uint32_t index, dm_block_t *new_root, bool *result)
  {
  	int r;
  	unsigned b = index % BITS_PER_ARRAY_ENTRY;
  
  	r = get_array_entry(info, root, index, new_root);
  	if (r)
  		return r;
  
  	*result = test_bit(b, (unsigned long *) &info->current_bits);
  	return 0;
  }
  EXPORT_SYMBOL_GPL(dm_bitset_test_bit);
  
  /*----------------------------------------------------------------*/
  