LXR linux/drivers/md/dm-cache-metadata.h

   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#include "persistent-data/dm-space-map-metadata.h"
  13
  14/*----------------------------------------------------------------*/
  15
  16#define DM_CACHE_METADATA_BLOCK_SIZE DM_SM_METADATA_BLOCK_SIZE
  17
  18/* FIXME: remove this restriction */
  19/*
  20 * The metadata device is currently limited in size.
  21 */
  22#define DM_CACHE_METADATA_MAX_SECTORS DM_SM_METADATA_MAX_SECTORS
  23
  24/*
  25 * A metadata device larger than 16GB triggers a warning.
  26 */
  27#define DM_CACHE_METADATA_MAX_SECTORS_WARNING (16 * (1024 * 1024 * 1024 >> SECTOR_SHIFT))
  28
  29/*----------------------------------------------------------------*/
  30
  31/*
  32 * Ext[234]-style compat feature flags.
  33 *
  34 * A new feature which old metadata will still be compatible with should
  35 * define a DM_CACHE_FEATURE_COMPAT_* flag (rarely useful).
  36 *
  37 * A new feature that is not compatible with old code should define a
  38 * DM_CACHE_FEATURE_INCOMPAT_* flag and guard the relevant code with
  39 * that flag.
  40 *
  41 * A new feature that is not compatible with old code accessing the
  42 * metadata RDWR should define a DM_CACHE_FEATURE_RO_COMPAT_* flag and
  43 * guard the relevant code with that flag.
  44 *
  45 * As these various flags are defined they should be added to the
  46 * following masks.
  47 */
  48
  49#define DM_CACHE_FEATURE_COMPAT_SUPP      0UL
  50#define DM_CACHE_FEATURE_COMPAT_RO_SUPP   0UL
  51#define DM_CACHE_FEATURE_INCOMPAT_SUPP    0UL
  52
  53struct dm_cache_metadata;
  54
  55/*
  56 * Reopens or creates a new, empty metadata volume.  Returns an ERR_PTR on
  57 * failure.  If reopening then features must match.
  58 */
  59struct dm_cache_metadata *dm_cache_metadata_open(struct block_device *bdev,
  60                                                 sector_t data_block_size,
  61                                                 bool may_format_device,
  62                                                 size_t policy_hint_size,
  63                                                 unsigned metadata_version);
  64
  65void dm_cache_metadata_close(struct dm_cache_metadata *cmd);
  66
  67/*
  68 * The metadata needs to know how many cache blocks there are.  We don't
  69 * care about the origin, assuming the core target is giving us valid
  70 * origin blocks to map to.
  71 */
  72int dm_cache_resize(struct dm_cache_metadata *cmd, dm_cblock_t new_cache_size);
  73int dm_cache_size(struct dm_cache_metadata *cmd, dm_cblock_t *result);
  74
  75int dm_cache_discard_bitset_resize(struct dm_cache_metadata *cmd,
  76                                   sector_t discard_block_size,
  77                                   dm_dblock_t new_nr_entries);
  78
  79typedef int (*load_discard_fn)(void *context, sector_t discard_block_size,
  80                               dm_dblock_t dblock, bool discarded);
  81int dm_cache_load_discards(struct dm_cache_metadata *cmd,
  82                           load_discard_fn fn, void *context);
  83
  84int dm_cache_set_discard(struct dm_cache_metadata *cmd, dm_dblock_t dblock, bool discard);
  85
  86int dm_cache_remove_mapping(struct dm_cache_metadata *cmd, dm_cblock_t cblock);
  87int dm_cache_insert_mapping(struct dm_cache_metadata *cmd, dm_cblock_t cblock, dm_oblock_t oblock);
  88int dm_cache_changed_this_transaction(struct dm_cache_metadata *cmd);
  89
  90typedef int (*load_mapping_fn)(void *context, dm_oblock_t oblock,
  91                               dm_cblock_t cblock, bool dirty,
  92                               uint32_t hint, bool hint_valid);
  93int dm_cache_load_mappings(struct dm_cache_metadata *cmd,
  94                           struct dm_cache_policy *policy,
  95                           load_mapping_fn fn,
  96                           void *context);
  97
  98int dm_cache_set_dirty_bits(struct dm_cache_metadata *cmd,
  99                            unsigned nr_bits, unsigned long *bits);
 100
 101struct dm_cache_statistics {
 102        uint32_t read_hits;
 103        uint32_t read_misses;
 104        uint32_t write_hits;
 105        uint32_t write_misses;
 106};
 107
 108void dm_cache_metadata_get_stats(struct dm_cache_metadata *cmd,
 109                                 struct dm_cache_statistics *stats);
 110
 111/*
 112 * 'void' because it's no big deal if it fails.
 113 */
 114void dm_cache_metadata_set_stats(struct dm_cache_metadata *cmd,
 115                                 struct dm_cache_statistics *stats);
 116
 117int dm_cache_commit(struct dm_cache_metadata *cmd, bool clean_shutdown);
 118
 119int dm_cache_get_free_metadata_block_count(struct dm_cache_metadata *cmd,
 120                                           dm_block_t *result);
 121
 122int dm_cache_get_metadata_dev_size(struct dm_cache_metadata *cmd,
 123                                   dm_block_t *result);
 124
 125void dm_cache_dump(struct dm_cache_metadata *cmd);
 126
 127/*
 128 * The policy is invited to save a 32bit hint value for every cblock (eg,
 129 * for a hit count).  These are stored against the policy name.  If
 130 * policies are changed, then hints will be lost.  If the machine crashes,
 131 * hints will be lost.
 132 *
 133 * The hints are indexed by the cblock, but many policies will not
 134 * neccessarily have a fast way of accessing efficiently via cblock.  So
 135 * rather than querying the policy for each cblock, we let it walk its data
 136 * structures and fill in the hints in whatever order it wishes.
 137 */
 138int dm_cache_write_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *p);
 139
 140/*
 141 * Query method.  Are all the blocks in the cache clean?
 142 */
 143int dm_cache_metadata_all_clean(struct dm_cache_metadata *cmd, bool *result);
 144
 145int dm_cache_metadata_needs_check(struct dm_cache_metadata *cmd, bool *result);
 146int dm_cache_metadata_set_needs_check(struct dm_cache_metadata *cmd);
 147void dm_cache_metadata_set_read_only(struct dm_cache_metadata *cmd);
 148void dm_cache_metadata_set_read_write(struct dm_cache_metadata *cmd);
 149int dm_cache_metadata_abort(struct dm_cache_metadata *cmd);
 150
 151/*----------------------------------------------------------------*/
 152
 153#endif /* DM_CACHE_METADATA_H */
 154