root/drivers/md/dm-cache-metadata.h

INCLUDED FROM

   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 
  53 struct 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  */
  59 struct 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 
  65 void 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  */
  72 int dm_cache_resize(struct dm_cache_metadata *cmd, dm_cblock_t new_cache_size);
  73 int dm_cache_size(struct dm_cache_metadata *cmd, dm_cblock_t *result);
  74 
  75 int dm_cache_discard_bitset_resize(struct dm_cache_metadata *cmd,
  76                                    sector_t discard_block_size,
  77                                    dm_dblock_t new_nr_entries);
  78 
  79 typedef int (*load_discard_fn)(void *context, sector_t discard_block_size,
  80                                dm_dblock_t dblock, bool discarded);
  81 int dm_cache_load_discards(struct dm_cache_metadata *cmd,
  82                            load_discard_fn fn, void *context);
  83 
  84 int dm_cache_set_discard(struct dm_cache_metadata *cmd, dm_dblock_t dblock, bool discard);
  85 
  86 int dm_cache_remove_mapping(struct dm_cache_metadata *cmd, dm_cblock_t cblock);
  87 int dm_cache_insert_mapping(struct dm_cache_metadata *cmd, dm_cblock_t cblock, dm_oblock_t oblock);
  88 int dm_cache_changed_this_transaction(struct dm_cache_metadata *cmd);
  89 
  90 typedef int (*load_mapping_fn)(void *context, dm_oblock_t oblock,
  91                                dm_cblock_t cblock, bool dirty,
  92                                uint32_t hint, bool hint_valid);
  93 int dm_cache_load_mappings(struct dm_cache_metadata *cmd,
  94                            struct dm_cache_policy *policy,
  95                            load_mapping_fn fn,
  96                            void *context);
  97 
  98 int dm_cache_set_dirty_bits(struct dm_cache_metadata *cmd,
  99                             unsigned nr_bits, unsigned long *bits);
 100 
 101 struct 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 
 108 void 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  */
 114 void dm_cache_metadata_set_stats(struct dm_cache_metadata *cmd,
 115                                  struct dm_cache_statistics *stats);
 116 
 117 int dm_cache_commit(struct dm_cache_metadata *cmd, bool clean_shutdown);
 118 
 119 int dm_cache_get_free_metadata_block_count(struct dm_cache_metadata *cmd,
 120                                            dm_block_t *result);
 121 
 122 int dm_cache_get_metadata_dev_size(struct dm_cache_metadata *cmd,
 123                                    dm_block_t *result);
 124 
 125 void 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  */
 138 int 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  */
 143 int dm_cache_metadata_all_clean(struct dm_cache_metadata *cmd, bool *result);
 144 
 145 int dm_cache_metadata_needs_check(struct dm_cache_metadata *cmd, bool *result);
 146 int dm_cache_metadata_set_needs_check(struct dm_cache_metadata *cmd);
 147 void dm_cache_metadata_set_read_only(struct dm_cache_metadata *cmd);
 148 void dm_cache_metadata_set_read_write(struct dm_cache_metadata *cmd);
 149 int dm_cache_metadata_abort(struct dm_cache_metadata *cmd);
 150 
 151 /*----------------------------------------------------------------*/
 152 
 153 #endif /* DM_CACHE_METADATA_H */