47 lines
1.8 KiB
C
47 lines
1.8 KiB
C
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/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Copyright 2023 Red Hat
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*/
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#ifndef UDS_SPARSE_CACHE_H
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#define UDS_SPARSE_CACHE_H
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#include "geometry.h"
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#include "indexer.h"
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/*
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* The sparse cache is a cache of entire chapter indexes from sparse chapters used for searching
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* for names after all other search paths have failed. It contains only complete chapter indexes;
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* record pages from sparse chapters and single index pages used for resolving hooks are kept in
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* the regular page cache in the volume.
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*
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* The most important property of this cache is the absence of synchronization for read operations.
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* Safe concurrent access to the cache by the zone threads is controlled by the triage queue and
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* the barrier requests it issues to the zone queues. The set of cached chapters does not and must
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* not change between the carefully coordinated calls to uds_update_sparse_cache() from the zone
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* threads. Outside of updates, every zone will get the same result when calling
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* uds_sparse_cache_contains() as every other zone.
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*/
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struct index_zone;
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struct sparse_cache;
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int __must_check uds_make_sparse_cache(const struct index_geometry *geometry,
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unsigned int capacity, unsigned int zone_count,
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struct sparse_cache **cache_ptr);
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void uds_free_sparse_cache(struct sparse_cache *cache);
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bool uds_sparse_cache_contains(struct sparse_cache *cache, u64 virtual_chapter,
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unsigned int zone_number);
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int __must_check uds_update_sparse_cache(struct index_zone *zone, u64 virtual_chapter);
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void uds_invalidate_sparse_cache(struct sparse_cache *cache);
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int __must_check uds_search_sparse_cache(struct index_zone *zone,
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const struct uds_record_name *name,
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u64 *virtual_chapter_ptr, u16 *record_page_ptr);
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#endif /* UDS_SPARSE_CACHE_H */
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