dm persistent data: add bitset

obj-$(CONFIG_DM_PERSISTENT_DATA) += dm-persistent-data.o

dm-persistent-data-objs := \

	dm-array.o \

	dm-bitset.o \

	dm-block-manager.o \

	dm-space-map-common.o \

	dm-space-map-disk.o \

/*

 * 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);

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

/*

 * Copyright (C) 2012 Red Hat, Inc.

 *

 * This file is released under the GPL.

 */

#ifndef _LINUX_DM_BITSET_H

#define _LINUX_DM_BITSET_H

#include "dm-array.h"

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

/*

 * This bitset type is a thin wrapper round a dm_array of 64bit words.  It

 * uses a tiny, one word cache to reduce the number of array lookups and so

 * increase performance.

 *

 * Like the dm-array that it's based on, the caller needs to keep track of

 * the size of the bitset separately.  The underlying dm-array implicitly

 * knows how many words it's storing and will return -ENODATA if you try

 * and access an out of bounds word.  However, an out of bounds bit in the

 * final word will _not_ be detected, you have been warned.

 *

 * Bits are indexed from zero.

 * Typical use:

 *

 * a) Initialise a dm_disk_bitset structure with dm_disk_bitset_init().

 *    This describes the bitset and includes the cache.  It's not called it

 *    dm_bitset_info in line with other data structures because it does

 *    include instance data.

 *

 * b) Get yourself a root.  The root is the index of a block of data on the

 *    disk that holds a particular instance of an bitset.  You may have a

 *    pre existing root in your metadata that you wish to use, or you may

 *    want to create a brand new, empty bitset with dm_bitset_empty().

 *

 * Like the other data structures in this library, dm_bitset objects are

 * immutable between transactions.  Update functions will return you the

 * root for a _new_ array.  If you've incremented the old root, via

 * dm_tm_inc(), before calling the update function you may continue to use

 * it in parallel with the new root.

 *

 * Even read operations may trigger the cache to be flushed and as such

 * return a root for a new, updated bitset.

 *

 * c) resize a bitset with dm_bitset_resize().

 *

 * d) Set a bit with dm_bitset_set_bit().

 *

 * e) Clear a bit with dm_bitset_clear_bit().

 *

 * f) Test a bit with dm_bitset_test_bit().

 *

 * g) Flush all updates from the cache with dm_bitset_flush().

 *

 * h) Destroy the bitset with dm_bitset_del().  This tells the transaction

 *    manager that you're no longer using this data structure so it can

 *    recycle it's blocks.  (dm_bitset_dec() would be a better name for it,

 *    but del is in keeping with dm_btree_del()).

 */

/*

 * Opaque object.  Unlike dm_array_info, you should have one of these per

 * bitset.  Initialise with dm_disk_bitset_init().

 */

struct dm_disk_bitset {

	struct dm_array_info array_info;

	uint32_t current_index;

	uint64_t current_bits;

	bool current_index_set:1;

};

/*

 * Sets up a dm_disk_bitset structure.  You don't need to do anything with

 * this structure when you finish using it.

 *

 * tm - the transaction manager that should supervise this structure

 * info - the structure being initialised

 */

void dm_disk_bitset_init(struct dm_transaction_manager *tm,

			 struct dm_disk_bitset *info);

/*

 * Create an empty, zero length bitset.

 *

 * info - describes the bitset

 * new_root - on success, points to the new root block

 */

int dm_bitset_empty(struct dm_disk_bitset *info, dm_block_t *new_root);

/*

 * Resize the bitset.

 *

 * info - describes the bitset

 * old_root - the root block of the array on disk

 * old_nr_entries - the number of bits in the old bitset

 * new_nr_entries - the number of bits you want in the new bitset

 * default_value - the value for any new bits

 * new_root - on success, points to the new root block

 */

int dm_bitset_resize(struct dm_disk_bitset *info, dm_block_t old_root,

		     uint32_t old_nr_entries, uint32_t new_nr_entries,

		     bool default_value, dm_block_t *new_root);

/*

 * Frees the bitset.

 */

int dm_bitset_del(struct dm_disk_bitset *info, dm_block_t root);

/*

 * Set a bit.

 *

 * info - describes the bitset

 * root - the root block of the bitset

 * index - the bit index

 * new_root - on success, points to the new root block

 *

 * -ENODATA will be returned if the index is out of bounds.

 */

int dm_bitset_set_bit(struct dm_disk_bitset *info, dm_block_t root,

		      uint32_t index, dm_block_t *new_root);

/*

 * Clears a bit.

 *

 * info - describes the bitset

 * root - the root block of the bitset

 * index - the bit index

 * new_root - on success, points to the new root block

 *

 * -ENODATA will be returned if the index is out of bounds.

 */

int dm_bitset_clear_bit(struct dm_disk_bitset *info, dm_block_t root,

			uint32_t index, dm_block_t *new_root);

/*

 * Tests a bit.

 *

 * info - describes the bitset

 * root - the root block of the bitset

 * index - the bit index

 * new_root - on success, points to the new root block (cached values may have been written)

 * result - the bit value you're after

 *

 * -ENODATA will be returned if the index is out of bounds.

 */

int dm_bitset_test_bit(struct dm_disk_bitset *info, dm_block_t root,

		       uint32_t index, dm_block_t *new_root, bool *result);

/*

 * Flush any cached changes to disk.

 *

 * info - describes the bitset

 * root - the root block of the bitset

 * new_root - on success, points to the new root block

 */

int dm_bitset_flush(struct dm_disk_bitset *info, dm_block_t root,

		    dm_block_t *new_root);

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

#endif /* _LINUX_DM_BITSET_H */