206 lines
6.4 KiB
C
206 lines
6.4 KiB
C
|
/*
|
||
|
|
* 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;
|
||
|
|
bool dirty: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);
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Creates a new bitset populated with values provided by a callback
|
||
|
|
* function. This is more efficient than creating an empty bitset,
|
||
|
|
* resizing, and then setting values since that process incurs a lot of
|
||
|
|
* copying.
|
||
|
|
*
|
||
|
|
* info - describes the array
|
||
|
|
* root - the root block of the array on disk
|
||
|
|
* size - the number of entries in the array
|
||
|
|
* fn - the callback
|
||
|
|
* context - passed to the callback
|
||
|
|
*/
|
||
|
|
typedef int (*bit_value_fn)(uint32_t index, bool *value, void *context);
|
||
|
|
int dm_bitset_new(struct dm_disk_bitset *info, dm_block_t *root,
|
||
|
|
uint32_t size, bit_value_fn fn, void *context);
|
||
|
|
|
||
|
|
/*
|
||
|
|
* 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);
|
||
|
|
|
||
|
|
struct dm_bitset_cursor {
|
||
|
|
struct dm_disk_bitset *info;
|
||
|
|
struct dm_array_cursor cursor;
|
||
|
|
|
||
|
|
uint32_t entries_remaining;
|
||
|
|
uint32_t array_index;
|
||
|
|
uint32_t bit_index;
|
||
|
|
uint64_t current_bits;
|
||
|
|
};
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Make sure you've flush any dm_disk_bitset and updated the root before
|
||
|
|
* using this.
|
||
|
|
*/
|
||
|
|
int dm_bitset_cursor_begin(struct dm_disk_bitset *info,
|
||
|
|
dm_block_t root, uint32_t nr_entries,
|
||
|
|
struct dm_bitset_cursor *c);
|
||
|
|
void dm_bitset_cursor_end(struct dm_bitset_cursor *c);
|
||
|
|
|
||
|
|
int dm_bitset_cursor_next(struct dm_bitset_cursor *c);
|
||
|
|
int dm_bitset_cursor_skip(struct dm_bitset_cursor *c, uint32_t count);
|
||
|
|
bool dm_bitset_cursor_get_value(struct dm_bitset_cursor *c);
|
||
|
|
|
||
|
|
/*----------------------------------------------------------------*/
|
||
|
|
|
||
|
|
#endif /* _LINUX_DM_BITSET_H */
|