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 #define DM_CACHE_FEATURE_COMPAT_SUPP      0UL
  49 #define DM_CACHE_FEATURE_COMPAT_RO_SUPP   0UL
  50 #define DM_CACHE_FEATURE_INCOMPAT_SUPP    0UL
  51
  52 /*
  53  * Reopens or creates a new, empty metadata volume.
  54  * Returns an ERR_PTR on failure.
  55  */
  56 struct dm_cache_metadata *dm_cache_metadata_open(struct block_device *bdev,
  57                                                  sector_t data_block_size,
  58                                                  bool may_format_device,
  59                                                  size_t policy_hint_size);
  60
  61 void dm_cache_metadata_close(struct dm_cache_metadata *cmd);
  62
  63 /*
  64  * The metadata needs to know how many cache blocks there are.  We don't
  65  * care about the origin, assuming the core target is giving us valid
  66  * origin blocks to map to.
  67  */
  68 int dm_cache_resize(struct dm_cache_metadata *cmd, dm_cblock_t new_cache_size);
  69 dm_cblock_t dm_cache_size(struct dm_cache_metadata *cmd);
  70
  71 int dm_cache_discard_bitset_resize(struct dm_cache_metadata *cmd,
  72                                    sector_t discard_block_size,
  73                                    dm_dblock_t new_nr_entries);
  74
  75 typedef int (*load_discard_fn)(void *context, sector_t discard_block_size,
  76                                dm_dblock_t dblock, bool discarded);
  77 int dm_cache_load_discards(struct dm_cache_metadata *cmd,
  78                            load_discard_fn fn, void *context);
  79
  80 int dm_cache_set_discard(struct dm_cache_metadata *cmd, dm_dblock_t dblock, bool discard);
  81
  82 int dm_cache_remove_mapping(struct dm_cache_metadata *cmd, dm_cblock_t cblock);
  83 int dm_cache_insert_mapping(struct dm_cache_metadata *cmd, dm_cblock_t cblock, dm_oblock_t oblock);
  84 int dm_cache_changed_this_transaction(struct dm_cache_metadata *cmd);
  85
  86 typedef int (*load_mapping_fn)(void *context, dm_oblock_t oblock,
  87                                dm_cblock_t cblock, bool dirty,
  88                                uint32_t hint, bool hint_valid);
  89 int dm_cache_load_mappings(struct dm_cache_metadata *cmd,
  90                            struct dm_cache_policy *policy,
  91                            load_mapping_fn fn,
  92                            void *context);
  93
  94 int dm_cache_set_dirty(struct dm_cache_metadata *cmd, dm_cblock_t cblock, bool dirty);
  95
  96 struct dm_cache_statistics {
  97         uint32_t read_hits;
  98         uint32_t read_misses;
  99         uint32_t write_hits;
 100         uint32_t write_misses;
 101 };
 102
 103 void dm_cache_metadata_get_stats(struct dm_cache_metadata *cmd,
 104                                  struct dm_cache_statistics *stats);
 105 void dm_cache_metadata_set_stats(struct dm_cache_metadata *cmd,
 106                                  struct dm_cache_statistics *stats);
 107
 108 int dm_cache_commit(struct dm_cache_metadata *cmd, bool clean_shutdown);
 109
 110 int dm_cache_get_free_metadata_block_count(struct dm_cache_metadata *cmd,
 111                                            dm_block_t *result);
 112
 113 int dm_cache_get_metadata_dev_size(struct dm_cache_metadata *cmd,
 114                                    dm_block_t *result);
 115
 116 void dm_cache_dump(struct dm_cache_metadata *cmd);
 117
 118 /*
 119  * The policy is invited to save a 32bit hint value for every cblock (eg,
 120  * for a hit count).  These are stored against the policy name.  If
 121  * policies are changed, then hints will be lost.  If the machine crashes,
 122  * hints will be lost.
 123  *
 124  * The hints are indexed by the cblock, but many policies will not
 125  * neccessarily have a fast way of accessing efficiently via cblock.  So
 126  * rather than querying the policy for each cblock, we let it walk its data
 127  * structures and fill in the hints in whatever order it wishes.
 128  */
 129 int dm_cache_write_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *p);
 130
 131 /*
 132  * Query method.  Are all the blocks in the cache clean?
 133  */
 134 int dm_cache_metadata_all_clean(struct dm_cache_metadata *cmd, bool *result);
 135
 136 /*----------------------------------------------------------------*/
 137
 138 #endif /* DM_CACHE_METADATA_H */