linux/drivers/md/dm-cache-metadata.h
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   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_dblock_t new_nr_entries);
  76
  77typedef int (*load_discard_fn)(void *context, sector_t discard_block_size,
  78                               dm_dblock_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_dblock_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 */
 131
 132int dm_cache_begin_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *p);
 133
 134/*
 135 * requests hints for every cblock and stores in the metadata device.
 136 */
 137int dm_cache_save_hint(struct dm_cache_metadata *cmd,
 138                       dm_cblock_t cblock, uint32_t hint);
 139
 140/*----------------------------------------------------------------*/
 141
 142#endif /* DM_CACHE_METADATA_H */
 143
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