diff options
Diffstat (limited to 'drivers/md/dm-cache-metadata.h')
| -rw-r--r-- | drivers/md/dm-cache-metadata.h | 142 |
1 files changed, 142 insertions, 0 deletions
diff --git a/drivers/md/dm-cache-metadata.h b/drivers/md/dm-cache-metadata.h new file mode 100644 index 00000000000..135864ea0ee --- /dev/null +++ b/drivers/md/dm-cache-metadata.h @@ -0,0 +1,142 @@ +/* + * Copyright (C) 2012 Red Hat, Inc. + * + * This file is released under the GPL. + */ + +#ifndef DM_CACHE_METADATA_H +#define DM_CACHE_METADATA_H + +#include "dm-cache-block-types.h" +#include "dm-cache-policy-internal.h" + +/*----------------------------------------------------------------*/ + +#define DM_CACHE_METADATA_BLOCK_SIZE 4096 + +/* FIXME: remove this restriction */ +/* + * The metadata device is currently limited in size. + * + * We have one block of index, which can hold 255 index entries. Each + * index entry contains allocation info about 16k metadata blocks. + */ +#define DM_CACHE_METADATA_MAX_SECTORS (255 * (1 << 14) * (DM_CACHE_METADATA_BLOCK_SIZE / (1 << SECTOR_SHIFT))) + +/* + * A metadata device larger than 16GB triggers a warning. + */ +#define DM_CACHE_METADATA_MAX_SECTORS_WARNING (16 * (1024 * 1024 * 1024 >> SECTOR_SHIFT)) + +/*----------------------------------------------------------------*/ + +/* + * Ext[234]-style compat feature flags. + * + * A new feature which old metadata will still be compatible with should + * define a DM_CACHE_FEATURE_COMPAT_* flag (rarely useful). + * + * A new feature that is not compatible with old code should define a + * DM_CACHE_FEATURE_INCOMPAT_* flag and guard the relevant code with + * that flag. + * + * A new feature that is not compatible with old code accessing the + * metadata RDWR should define a DM_CACHE_FEATURE_RO_COMPAT_* flag and + * guard the relevant code with that flag. + * + * As these various flags are defined they should be added to the + * following masks. + */ +#define DM_CACHE_FEATURE_COMPAT_SUPP 0UL +#define DM_CACHE_FEATURE_COMPAT_RO_SUPP 0UL +#define DM_CACHE_FEATURE_INCOMPAT_SUPP 0UL + +/* + * Reopens or creates a new, empty metadata volume. + * Returns an ERR_PTR on failure. + */ +struct dm_cache_metadata *dm_cache_metadata_open(struct block_device *bdev, + sector_t data_block_size, + bool may_format_device, + size_t policy_hint_size); + +void dm_cache_metadata_close(struct dm_cache_metadata *cmd); + +/* + * The metadata needs to know how many cache blocks there are. We don't + * care about the origin, assuming the core target is giving us valid + * origin blocks to map to. + */ +int dm_cache_resize(struct dm_cache_metadata *cmd, dm_cblock_t new_cache_size); +dm_cblock_t dm_cache_size(struct dm_cache_metadata *cmd); + +int dm_cache_discard_bitset_resize(struct dm_cache_metadata *cmd, + sector_t discard_block_size, + dm_dblock_t new_nr_entries); + +typedef int (*load_discard_fn)(void *context, sector_t discard_block_size, + dm_dblock_t dblock, bool discarded); +int dm_cache_load_discards(struct dm_cache_metadata *cmd, + load_discard_fn fn, void *context); + +int dm_cache_set_discard(struct dm_cache_metadata *cmd, dm_dblock_t dblock, bool discard); + +int dm_cache_remove_mapping(struct dm_cache_metadata *cmd, dm_cblock_t cblock); +int dm_cache_insert_mapping(struct dm_cache_metadata *cmd, dm_cblock_t cblock, dm_oblock_t oblock); +int dm_cache_changed_this_transaction(struct dm_cache_metadata *cmd); + +typedef int (*load_mapping_fn)(void *context, dm_oblock_t oblock, + dm_cblock_t cblock, bool dirty, + uint32_t hint, bool hint_valid); +int dm_cache_load_mappings(struct dm_cache_metadata *cmd, + const char *policy_name, + load_mapping_fn fn, + void *context); + +int dm_cache_set_dirty(struct dm_cache_metadata *cmd, dm_cblock_t cblock, bool dirty); + +struct dm_cache_statistics { + uint32_t read_hits; + uint32_t read_misses; + uint32_t write_hits; + uint32_t write_misses; +}; + +void dm_cache_metadata_get_stats(struct dm_cache_metadata *cmd, + struct dm_cache_statistics *stats); +void dm_cache_metadata_set_stats(struct dm_cache_metadata *cmd, + struct dm_cache_statistics *stats); + +int dm_cache_commit(struct dm_cache_metadata *cmd, bool clean_shutdown); + +int dm_cache_get_free_metadata_block_count(struct dm_cache_metadata *cmd, + dm_block_t *result); + +int dm_cache_get_metadata_dev_size(struct dm_cache_metadata *cmd, + dm_block_t *result); + +void dm_cache_dump(struct dm_cache_metadata *cmd); + +/* + * The policy is invited to save a 32bit hint value for every cblock (eg, + * for a hit count). These are stored against the policy name. If + * policies are changed, then hints will be lost. If the machine crashes, + * hints will be lost. + * + * The hints are indexed by the cblock, but many policies will not + * neccessarily have a fast way of accessing efficiently via cblock. So + * rather than querying the policy for each cblock, we let it walk its data + * structures and fill in the hints in whatever order it wishes. + */ + +int dm_cache_begin_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *p); + +/* + * requests hints for every cblock and stores in the metadata device. + */ +int dm_cache_save_hint(struct dm_cache_metadata *cmd, + dm_cblock_t cblock, uint32_t hint); + +/*----------------------------------------------------------------*/ + +#endif /* DM_CACHE_METADATA_H */ |