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 */ 47