1. 根目录:
2. drivers
3. md
4. persistent-data
5. dm-bitset.c

/*
 * 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);

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