1/*
  2 * Copyright (C) 2012 Red Hat, Inc.
  3 *
  4 * This file is released under the GPL.
  5 */
  6
  7#ifndef DM_CACHE_METADATA_H
  8#define DM_CACHE_METADATA_H
  9
 10#include "dm-cache-block-types.h"
 11#include "dm-cache-policy-internal.h"
 12
 13/*----------------------------------------------------------------*/
 14
 15#define DM_CACHE_METADATA_BLOCK_SIZE 4096
 16
 17/* FIXME: remove this restriction */
 18/*
 19 * The metadata device is currently limited in size.
 20 *
 21 * We have one block of index, which can hold 255 index entries.  Each
 22 * index entry contains allocation info about 16k metadata blocks.
 23 */
 24#define DM_CACHE_METADATA_MAX_SECTORS (255 * (1 << 14) * (DM_CACHE_METADATA_BLOCK_SIZE / (1 << SECTOR_SHIFT)))
 25
 26/*
 27 * A metadata device larger than 16GB triggers a warning.
 28 */
 29#define DM_CACHE_METADATA_MAX_SECTORS_WARNING (16 * (1024 * 1024 * 1024 >> SECTOR_SHIFT))
 30
 31/*----------------------------------------------------------------*/
 32
 33/*
 34 * Ext[234]-style compat feature flags.
 35 *
 36 * A new feature which old metadata will still be compatible with should
 37 * define a DM_CACHE_FEATURE_COMPAT_* flag (rarely useful).
 38 *
 39 * A new feature that is not compatible with old code should define a
 40 * DM_CACHE_FEATURE_INCOMPAT_* flag and guard the relevant code with
 41 * that flag.
 42 *
 43 * A new feature that is not compatible with old code accessing the
 44 * metadata RDWR should define a DM_CACHE_FEATURE_RO_COMPAT_* flag and
 45 * guard the relevant code with that flag.
 46 *
 47 * As these various flags are defined they should be added to the
 48 * following masks.
 49 */
 50#define DM_CACHE_FEATURE_COMPAT_SUPP	  0UL
 51#define DM_CACHE_FEATURE_COMPAT_RO_SUPP	  0UL
 52#define DM_CACHE_FEATURE_INCOMPAT_SUPP	  0UL
 53
 54/*
 55 * Reopens or creates a new, empty metadata volume.
 56 * Returns an ERR_PTR on failure.
 57 */
 58struct dm_cache_metadata *dm_cache_metadata_open(struct block_device *bdev,
 59						 sector_t data_block_size,
 60						 bool may_format_device,
 61						 size_t policy_hint_size);
 62
 63void dm_cache_metadata_close(struct dm_cache_metadata *cmd);
 64
 65/*
 66 * The metadata needs to know how many cache blocks there are.  We don't
 67 * care about the origin, assuming the core target is giving us valid
 68 * origin blocks to map to.
 69 */
 70int dm_cache_resize(struct dm_cache_metadata *cmd, dm_cblock_t new_cache_size);
 71dm_cblock_t dm_cache_size(struct dm_cache_metadata *cmd);
 72
 73int dm_cache_discard_bitset_resize(struct dm_cache_metadata *cmd,
 74				   sector_t discard_block_size,
 75				   dm_oblock_t new_nr_entries);
 76
 77typedef int (*load_discard_fn)(void *context, sector_t discard_block_size,
 78			       dm_oblock_t dblock, bool discarded);
 79int dm_cache_load_discards(struct dm_cache_metadata *cmd,
 80			   load_discard_fn fn, void *context);
 81
 82int dm_cache_set_discard(struct dm_cache_metadata *cmd, dm_oblock_t dblock, bool discard);
 83
 84int dm_cache_remove_mapping(struct dm_cache_metadata *cmd, dm_cblock_t cblock);
 85int dm_cache_insert_mapping(struct dm_cache_metadata *cmd, dm_cblock_t cblock, dm_oblock_t oblock);
 86int dm_cache_changed_this_transaction(struct dm_cache_metadata *cmd);
 87
 88typedef int (*load_mapping_fn)(void *context, dm_oblock_t oblock,
 89			       dm_cblock_t cblock, bool dirty,
 90			       uint32_t hint, bool hint_valid);
 91int dm_cache_load_mappings(struct dm_cache_metadata *cmd,
 92			   struct dm_cache_policy *policy,
 93			   load_mapping_fn fn,
 94			   void *context);
 95
 96int dm_cache_set_dirty(struct dm_cache_metadata *cmd, dm_cblock_t cblock, bool dirty);
 97
 98struct dm_cache_statistics {
 99	uint32_t read_hits;
100	uint32_t read_misses;
101	uint32_t write_hits;
102	uint32_t write_misses;
103};
104
105void dm_cache_metadata_get_stats(struct dm_cache_metadata *cmd,
106				 struct dm_cache_statistics *stats);
107void dm_cache_metadata_set_stats(struct dm_cache_metadata *cmd,
108				 struct dm_cache_statistics *stats);
109
110int dm_cache_commit(struct dm_cache_metadata *cmd, bool clean_shutdown);
111
112int dm_cache_get_free_metadata_block_count(struct dm_cache_metadata *cmd,
113					   dm_block_t *result);
114
115int dm_cache_get_metadata_dev_size(struct dm_cache_metadata *cmd,
116				   dm_block_t *result);
117
118void dm_cache_dump(struct dm_cache_metadata *cmd);
119
120/*
121 * The policy is invited to save a 32bit hint value for every cblock (eg,
122 * for a hit count).  These are stored against the policy name.  If
123 * policies are changed, then hints will be lost.  If the machine crashes,
124 * hints will be lost.
125 *
126 * The hints are indexed by the cblock, but many policies will not
127 * neccessarily have a fast way of accessing efficiently via cblock.  So
128 * rather than querying the policy for each cblock, we let it walk its data
129 * structures and fill in the hints in whatever order it wishes.
130 */
131int dm_cache_write_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *p);
132
133/*
134 * Query method.  Are all the blocks in the cache clean?
135 */
136int dm_cache_metadata_all_clean(struct dm_cache_metadata *cmd, bool *result);
137
138/*----------------------------------------------------------------*/
139
140#endif /* DM_CACHE_METADATA_H */