dm persistent data: add bitset

Add a persistent bitset as a wrapper around dm-array.

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
This commit is contained in:
Joe Thornber 2013-03-01 22:45:51 +00:00 committed by Alasdair G Kergon
parent 6513c29f44
commit 7a87edfee7
3 changed files with 329 additions and 0 deletions

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@ -1,6 +1,7 @@
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 \

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/*
* 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);
/*----------------------------------------------------------------*/

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/*
* 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 */