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dm-cache-metadata.h
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dm-cache-metadata.h
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/*
* Copyright (C) 2012 Red Hat, Inc.
*
* This file is released under the GPL.
*/
#ifndef DM_CACHE_METADATA_H
#define DM_CACHE_METADATA_H
#include "dm-cache-block-types.h"
#include "dm-cache-policy-internal.h"
/*----------------------------------------------------------------*/
#define DM_CACHE_METADATA_BLOCK_SIZE 4096
/* FIXME: remove this restriction */
/*
* The metadata device is currently limited in size.
*
* We have one block of index, which can hold 255 index entries. Each
* index entry contains allocation info about 16k metadata blocks.
*/
#define DM_CACHE_METADATA_MAX_SECTORS (255 * (1 << 14) * (DM_CACHE_METADATA_BLOCK_SIZE / (1 << SECTOR_SHIFT)))
/*
* A metadata device larger than 16GB triggers a warning.
*/
#define DM_CACHE_METADATA_MAX_SECTORS_WARNING (16 * (1024 * 1024 * 1024 >> SECTOR_SHIFT))
/*----------------------------------------------------------------*/
/*
* Ext[234]-style compat feature flags.
*
* A new feature which old metadata will still be compatible with should
* define a DM_CACHE_FEATURE_COMPAT_* flag (rarely useful).
*
* A new feature that is not compatible with old code should define a
* DM_CACHE_FEATURE_INCOMPAT_* flag and guard the relevant code with
* that flag.
*
* A new feature that is not compatible with old code accessing the
* metadata RDWR should define a DM_CACHE_FEATURE_RO_COMPAT_* flag and
* guard the relevant code with that flag.
*
* As these various flags are defined they should be added to the
* following masks.
*/
#define DM_CACHE_FEATURE_COMPAT_SUPP 0UL
#define DM_CACHE_FEATURE_COMPAT_RO_SUPP 0UL
#define DM_CACHE_FEATURE_INCOMPAT_SUPP 0UL
/*
* Reopens or creates a new, empty metadata volume.
* Returns an ERR_PTR on failure.
*/
struct dm_cache_metadata *dm_cache_metadata_open(struct block_device *bdev,
sector_t data_block_size,
bool may_format_device,
size_t policy_hint_size);
void dm_cache_metadata_close(struct dm_cache_metadata *cmd);
/*
* The metadata needs to know how many cache blocks there are. We don't
* care about the origin, assuming the core target is giving us valid
* origin blocks to map to.
*/
int dm_cache_resize(struct dm_cache_metadata *cmd, dm_cblock_t new_cache_size);
dm_cblock_t dm_cache_size(struct dm_cache_metadata *cmd);
int dm_cache_discard_bitset_resize(struct dm_cache_metadata *cmd,
sector_t discard_block_size,
dm_dblock_t new_nr_entries);
typedef int (*load_discard_fn)(void *context, sector_t discard_block_size,
dm_dblock_t dblock, bool discarded);
int dm_cache_load_discards(struct dm_cache_metadata *cmd,
load_discard_fn fn, void *context);
int dm_cache_set_discard(struct dm_cache_metadata *cmd, dm_dblock_t dblock, bool discard);
int dm_cache_remove_mapping(struct dm_cache_metadata *cmd, dm_cblock_t cblock);
int dm_cache_insert_mapping(struct dm_cache_metadata *cmd, dm_cblock_t cblock, dm_oblock_t oblock);
int dm_cache_changed_this_transaction(struct dm_cache_metadata *cmd);
typedef int (*load_mapping_fn)(void *context, dm_oblock_t oblock,
dm_cblock_t cblock, bool dirty,
uint32_t hint, bool hint_valid);
int dm_cache_load_mappings(struct dm_cache_metadata *cmd,
struct dm_cache_policy *policy,
load_mapping_fn fn,
void *context);
int dm_cache_set_dirty(struct dm_cache_metadata *cmd, dm_cblock_t cblock, bool dirty);
struct dm_cache_statistics {
uint32_t read_hits;
uint32_t read_misses;
uint32_t write_hits;
uint32_t write_misses;
};
void dm_cache_metadata_get_stats(struct dm_cache_metadata *cmd,
struct dm_cache_statistics *stats);
void dm_cache_metadata_set_stats(struct dm_cache_metadata *cmd,
struct dm_cache_statistics *stats);
int dm_cache_commit(struct dm_cache_metadata *cmd, bool clean_shutdown);
int dm_cache_get_free_metadata_block_count(struct dm_cache_metadata *cmd,
dm_block_t *result);
int dm_cache_get_metadata_dev_size(struct dm_cache_metadata *cmd,
dm_block_t *result);
void dm_cache_dump(struct dm_cache_metadata *cmd);
/*
* The policy is invited to save a 32bit hint value for every cblock (eg,
* for a hit count). These are stored against the policy name. If
* policies are changed, then hints will be lost. If the machine crashes,
* hints will be lost.
*
* The hints are indexed by the cblock, but many policies will not
* neccessarily have a fast way of accessing efficiently via cblock. So
* rather than querying the policy for each cblock, we let it walk its data
* structures and fill in the hints in whatever order it wishes.
*/
int dm_cache_begin_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *p);
/*
* requests hints for every cblock and stores in the metadata device.
*/
int dm_cache_save_hint(struct dm_cache_metadata *cmd,
dm_cblock_t cblock, uint32_t hint);
/*----------------------------------------------------------------*/
#endif /* DM_CACHE_METADATA_H */