drivers/md/dm-vdo/indexer/hash-utils.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  * Copyright 2023 Red Hat
   4  */
   5
   6 #ifndef UDS_HASH_UTILS_H
   7 #define UDS_HASH_UTILS_H
   8
   9 #include "numeric.h"
  10
  11 #include "geometry.h"
  12 #include "indexer.h"
  13
  14 /* Utilities for extracting portions of a request name for various uses. */
  15
  16 /* How various portions of a record name are apportioned. */
  17 enum {
  18         VOLUME_INDEX_BYTES_OFFSET = 0,
  19         VOLUME_INDEX_BYTES_COUNT = 8,
  20         CHAPTER_INDEX_BYTES_OFFSET = 8,
  21         CHAPTER_INDEX_BYTES_COUNT = 6,
  22         SAMPLE_BYTES_OFFSET = 14,
  23         SAMPLE_BYTES_COUNT = 2,
  24 };
  25
  26 static inline u64 uds_extract_chapter_index_bytes(const struct uds_record_name *name)
  27 {
  28         const u8 *chapter_bits = &name->name[CHAPTER_INDEX_BYTES_OFFSET];
  29         u64 bytes = (u64) get_unaligned_be16(chapter_bits) << 32;
  30
  31         bytes |= get_unaligned_be32(chapter_bits + 2);
  32         return bytes;
  33 }
  34
  35 static inline u64 uds_extract_volume_index_bytes(const struct uds_record_name *name)
  36 {
  37         return get_unaligned_be64(&name->name[VOLUME_INDEX_BYTES_OFFSET]);
  38 }
  39
  40 static inline u32 uds_extract_sampling_bytes(const struct uds_record_name *name)
  41 {
  42         return get_unaligned_be16(&name->name[SAMPLE_BYTES_OFFSET]);
  43 }
  44
  45 /* Compute the chapter delta list for a given name. */
  46 static inline u32 uds_hash_to_chapter_delta_list(const struct uds_record_name *name,
  47                                                  const struct index_geometry *geometry)
  48 {
  49         return ((uds_extract_chapter_index_bytes(name) >> geometry->chapter_address_bits) &
  50                 ((1 << geometry->chapter_delta_list_bits) - 1));
  51 }
  52
  53 /* Compute the chapter delta address for a given name. */
  54 static inline u32 uds_hash_to_chapter_delta_address(const struct uds_record_name *name,
  55                                                     const struct index_geometry *geometry)
  56 {
  57         return uds_extract_chapter_index_bytes(name) & ((1 << geometry->chapter_address_bits) - 1);
  58 }
  59
  60 static inline unsigned int uds_name_to_hash_slot(const struct uds_record_name *name,
  61                                                  unsigned int slot_count)
  62 {
  63         return (unsigned int) (uds_extract_chapter_index_bytes(name) % slot_count);
  64 }
  65
  66 #endif /* UDS_HASH_UTILS_H */