drivers/md/dm-vdo/indexer/sparse-cache.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  * Copyright 2023 Red Hat
   4  */
   5
   6 #ifndef UDS_SPARSE_CACHE_H
   7 #define UDS_SPARSE_CACHE_H
   8
   9 #include "geometry.h"
  10 #include "indexer.h"
  11
  12 /*
  13  * The sparse cache is a cache of entire chapter indexes from sparse chapters used for searching
  14  * for names after all other search paths have failed. It contains only complete chapter indexes;
  15  * record pages from sparse chapters and single index pages used for resolving hooks are kept in
  16  * the regular page cache in the volume.
  17  *
  18  * The most important property of this cache is the absence of synchronization for read operations.
  19  * Safe concurrent access to the cache by the zone threads is controlled by the triage queue and
  20  * the barrier requests it issues to the zone queues. The set of cached chapters does not and must
  21  * not change between the carefully coordinated calls to uds_update_sparse_cache() from the zone
  22  * threads. Outside of updates, every zone will get the same result when calling
  23  * uds_sparse_cache_contains() as every other zone.
  24  */
  25
  26 struct index_zone;
  27 struct sparse_cache;
  28
  29 int __must_check uds_make_sparse_cache(const struct index_geometry *geometry,
  30                                        unsigned int capacity, unsigned int zone_count,
  31                                        struct sparse_cache **cache_ptr);
  32
  33 void uds_free_sparse_cache(struct sparse_cache *cache);
  34
  35 bool uds_sparse_cache_contains(struct sparse_cache *cache, u64 virtual_chapter,
  36                                unsigned int zone_number);
  37
  38 int __must_check uds_update_sparse_cache(struct index_zone *zone, u64 virtual_chapter);
  39
  40 void uds_invalidate_sparse_cache(struct sparse_cache *cache);
  41
  42 int __must_check uds_search_sparse_cache(struct index_zone *zone,
  43                                          const struct uds_record_name *name,
  44                                          u64 *virtual_chapter_ptr, u16 *record_page_ptr);
  45
  46 #endif /* UDS_SPARSE_CACHE_H */