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
  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  */
  58 struct 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
  63 void 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  */
  70 int dm_cache_resize(struct dm_cache_metadata *cmd, dm_cblock_t new_cache_size);
  71 dm_cblock_t dm_cache_size(struct dm_cache_metadata *cmd);
  72
  73 int dm_cache_discard_bitset_resize(struct dm_cache_metadata *cmd,
  74                                    sector_t discard_block_size,
  75                                    dm_dblock_t new_nr_entries);
  76
  77 typedef int (*load_discard_fn)(void *context, sector_t discard_block_size,
  78                                dm_dblock_t dblock, bool discarded);
  79 int dm_cache_load_discards(struct dm_cache_metadata *cmd,
  80                            load_discard_fn fn, void *context);
  81
  82 int dm_cache_set_discard(struct dm_cache_metadata *cmd, dm_dblock_t dblock, bool discard);
  83
  84 int dm_cache_remove_mapping(struct dm_cache_metadata *cmd, dm_cblock_t cblock);
  85 int dm_cache_insert_mapping(struct dm_cache_metadata *cmd, dm_cblock_t cblock, dm_oblock_t oblock);
  86 int dm_cache_changed_this_transaction(struct dm_cache_metadata *cmd);
  87
  88 typedef int (*load_mapping_fn)(void *context, dm_oblock_t oblock,
  89                                dm_cblock_t cblock, bool dirty,
  90                                uint32_t hint, bool hint_valid);
  91 int dm_cache_load_mappings(struct dm_cache_metadata *cmd,
  92                            struct dm_cache_policy *policy,
  93                            load_mapping_fn fn,
  94                            void *context);
  95
  96 int dm_cache_set_dirty(struct dm_cache_metadata *cmd, dm_cblock_t cblock, bool dirty);
  97
  98 struct 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
 105 void dm_cache_metadata_get_stats(struct dm_cache_metadata *cmd,
 106                                  struct dm_cache_statistics *stats);
 107 void dm_cache_metadata_set_stats(struct dm_cache_metadata *cmd,
 108                                  struct dm_cache_statistics *stats);
 109
 110 int dm_cache_commit(struct dm_cache_metadata *cmd, bool clean_shutdown);
 111
 112 int dm_cache_get_free_metadata_block_count(struct dm_cache_metadata *cmd,
 113                                            dm_block_t *result);
 114
 115 int dm_cache_get_metadata_dev_size(struct dm_cache_metadata *cmd,
 116                                    dm_block_t *result);
 117
 118 void 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
 132 int 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  */
 137 int 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 */