drivers/md/persistent-data/dm-bitset.c

   1 /*
   2  * Copyright (C) 2012 Red Hat, Inc.
   3  *
   4  * This file is released under the GPL.
   5  */
   6
   7 #include "dm-bitset.h"
   8 #include "dm-transaction-manager.h"
   9
  10 #include <linux/export.h>
  11 #include <linux/device-mapper.h>
  12
  13 #define DM_MSG_PREFIX "bitset"
  14 #define BITS_PER_ARRAY_ENTRY 64
  15
  16 /*----------------------------------------------------------------*/
  17
  18 static struct dm_btree_value_type bitset_bvt = {
  19         .context = NULL,
  20         .size = sizeof(__le64),
  21         .inc = NULL,
  22         .dec = NULL,
  23         .equal = NULL,
  24 };
  25
  26 /*----------------------------------------------------------------*/
  27
  28 void dm_disk_bitset_init(struct dm_transaction_manager *tm,
  29                          struct dm_disk_bitset *info)
  30 {
  31         dm_array_info_init(&info->array_info, tm, &bitset_bvt);
  32         info->current_index_set = false;
  33 }
  34 EXPORT_SYMBOL_GPL(dm_disk_bitset_init);
  35
  36 int dm_bitset_empty(struct dm_disk_bitset *info, dm_block_t *root)
  37 {
  38         return dm_array_empty(&info->array_info, root);
  39 }
  40 EXPORT_SYMBOL_GPL(dm_bitset_empty);
  41
  42 int dm_bitset_resize(struct dm_disk_bitset *info, dm_block_t root,
  43                      uint32_t old_nr_entries, uint32_t new_nr_entries,
  44                      bool default_value, dm_block_t *new_root)
  45 {
  46         uint32_t old_blocks = dm_div_up(old_nr_entries, BITS_PER_ARRAY_ENTRY);
  47         uint32_t new_blocks = dm_div_up(new_nr_entries, BITS_PER_ARRAY_ENTRY);
  48         __le64 value = default_value ? cpu_to_le64(~0) : cpu_to_le64(0);
  49
  50         __dm_bless_for_disk(&value);
  51         return dm_array_resize(&info->array_info, root, old_blocks, new_blocks,
  52                                &value, new_root);
  53 }
  54 EXPORT_SYMBOL_GPL(dm_bitset_resize);
  55
  56 int dm_bitset_del(struct dm_disk_bitset *info, dm_block_t root)
  57 {
  58         return dm_array_del(&info->array_info, root);
  59 }
  60 EXPORT_SYMBOL_GPL(dm_bitset_del);
  61
  62 int dm_bitset_flush(struct dm_disk_bitset *info, dm_block_t root,
  63                     dm_block_t *new_root)
  64 {
  65         int r;
  66         __le64 value;
  67
  68         if (!info->current_index_set || !info->dirty)
  69                 return 0;
  70
  71         value = cpu_to_le64(info->current_bits);
  72
  73         __dm_bless_for_disk(&value);
  74         r = dm_array_set_value(&info->array_info, root, info->current_index,
  75                                &value, new_root);
  76         if (r)
  77                 return r;
  78
  79         info->current_index_set = false;
  80         info->dirty = false;
  81
  82         return 0;
  83 }
  84 EXPORT_SYMBOL_GPL(dm_bitset_flush);
  85
  86 static int read_bits(struct dm_disk_bitset *info, dm_block_t root,
  87                      uint32_t array_index)
  88 {
  89         int r;
  90         __le64 value;
  91
  92         r = dm_array_get_value(&info->array_info, root, array_index, &value);
  93         if (r)
  94                 return r;
  95
  96         info->current_bits = le64_to_cpu(value);
  97         info->current_index_set = true;
  98         info->current_index = array_index;
  99         info->dirty = false;
 100
 101         return 0;
 102 }
 103
 104 static int get_array_entry(struct dm_disk_bitset *info, dm_block_t root,
 105                            uint32_t index, dm_block_t *new_root)
 106 {
 107         int r;
 108         unsigned array_index = index / BITS_PER_ARRAY_ENTRY;
 109
 110         if (info->current_index_set) {
 111                 if (info->current_index == array_index)
 112                         return 0;
 113
 114                 r = dm_bitset_flush(info, root, new_root);
 115                 if (r)
 116                         return r;
 117         }
 118
 119         return read_bits(info, root, array_index);
 120 }
 121
 122 int dm_bitset_set_bit(struct dm_disk_bitset *info, dm_block_t root,
 123                       uint32_t index, dm_block_t *new_root)
 124 {
 125         int r;
 126         unsigned b = index % BITS_PER_ARRAY_ENTRY;
 127
 128         r = get_array_entry(info, root, index, new_root);
 129         if (r)
 130                 return r;
 131
 132         set_bit(b, (unsigned long *) &info->current_bits);
 133         info->dirty = true;
 134
 135         return 0;
 136 }
 137 EXPORT_SYMBOL_GPL(dm_bitset_set_bit);
 138
 139 int dm_bitset_clear_bit(struct dm_disk_bitset *info, dm_block_t root,
 140                         uint32_t index, dm_block_t *new_root)
 141 {
 142         int r;
 143         unsigned b = index % BITS_PER_ARRAY_ENTRY;
 144
 145         r = get_array_entry(info, root, index, new_root);
 146         if (r)
 147                 return r;
 148
 149         clear_bit(b, (unsigned long *) &info->current_bits);
 150         info->dirty = true;
 151
 152         return 0;
 153 }
 154 EXPORT_SYMBOL_GPL(dm_bitset_clear_bit);
 155
 156 int dm_bitset_test_bit(struct dm_disk_bitset *info, dm_block_t root,
 157                        uint32_t index, dm_block_t *new_root, bool *result)
 158 {
 159         int r;
 160         unsigned b = index % BITS_PER_ARRAY_ENTRY;
 161
 162         r = get_array_entry(info, root, index, new_root);
 163         if (r)
 164                 return r;
 165
 166         *result = test_bit(b, (unsigned long *) &info->current_bits);
 167         return 0;
 168 }
 169 EXPORT_SYMBOL_GPL(dm_bitset_test_bit);
 170
 171 /*----------------------------------------------------------------*/