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

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2012 Red Hat, Inc.
   4  *
   5  * This file is released under the GPL.
   6  */
   7
   8 #include "dm-bitset.h"
   9 #include "dm-transaction-manager.h"
  10
  11 #include <linux/export.h>
  12 #include <linux/device-mapper.h>
  13
  14 #define DM_MSG_PREFIX "bitset"
  15 #define BITS_PER_ARRAY_ENTRY 64
  16
  17 /*----------------------------------------------------------------*/
  18
  19 static struct dm_btree_value_type bitset_bvt = {
  20         .context = NULL,
  21         .size = sizeof(__le64),
  22         .inc = NULL,
  23         .dec = NULL,
  24         .equal = NULL,
  25 };
  26
  27 /*----------------------------------------------------------------*/
  28
  29 void dm_disk_bitset_init(struct dm_transaction_manager *tm,
  30                          struct dm_disk_bitset *info)
  31 {
  32         dm_array_info_init(&info->array_info, tm, &bitset_bvt);
  33         info->current_index_set = false;
  34 }
  35 EXPORT_SYMBOL_GPL(dm_disk_bitset_init);
  36
  37 int dm_bitset_empty(struct dm_disk_bitset *info, dm_block_t *root)
  38 {
  39         return dm_array_empty(&info->array_info, root);
  40 }
  41 EXPORT_SYMBOL_GPL(dm_bitset_empty);
  42
  43 struct packer_context {
  44         bit_value_fn fn;
  45         unsigned int nr_bits;
  46         void *context;
  47 };
  48
  49 static int pack_bits(uint32_t index, void *value, void *context)
  50 {
  51         int r;
  52         struct packer_context *p = context;
  53         unsigned int bit, nr = min(64u, p->nr_bits - (index * 64));
  54         uint64_t word = 0;
  55         bool bv;
  56
  57         for (bit = 0; bit < nr; bit++) {
  58                 r = p->fn(index * 64 + bit, &bv, p->context);
  59                 if (r)
  60                         return r;
  61
  62                 if (bv)
  63                         set_bit(bit, (unsigned long *) &word);
  64                 else
  65                         clear_bit(bit, (unsigned long *) &word);
  66         }
  67
  68         *((__le64 *) value) = cpu_to_le64(word);
  69
  70         return 0;
  71 }
  72
  73 int dm_bitset_new(struct dm_disk_bitset *info, dm_block_t *root,
  74                   uint32_t size, bit_value_fn fn, void *context)
  75 {
  76         struct packer_context p;
  77
  78         p.fn = fn;
  79         p.nr_bits = size;
  80         p.context = context;
  81
  82         return dm_array_new(&info->array_info, root, dm_div_up(size, 64), pack_bits, &p);
  83 }
  84 EXPORT_SYMBOL_GPL(dm_bitset_new);
  85
  86 int dm_bitset_resize(struct dm_disk_bitset *info, dm_block_t root,
  87                      uint32_t old_nr_entries, uint32_t new_nr_entries,
  88                      bool default_value, dm_block_t *new_root)
  89 {
  90         uint32_t old_blocks = dm_div_up(old_nr_entries, BITS_PER_ARRAY_ENTRY);
  91         uint32_t new_blocks = dm_div_up(new_nr_entries, BITS_PER_ARRAY_ENTRY);
  92         __le64 value = default_value ? cpu_to_le64(~0) : cpu_to_le64(0);
  93
  94         __dm_bless_for_disk(&value);
  95         return dm_array_resize(&info->array_info, root, old_blocks, new_blocks,
  96                                &value, new_root);
  97 }
  98 EXPORT_SYMBOL_GPL(dm_bitset_resize);
  99
 100 int dm_bitset_del(struct dm_disk_bitset *info, dm_block_t root)
 101 {
 102         return dm_array_del(&info->array_info, root);
 103 }
 104 EXPORT_SYMBOL_GPL(dm_bitset_del);
 105
 106 int dm_bitset_flush(struct dm_disk_bitset *info, dm_block_t root,
 107                     dm_block_t *new_root)
 108 {
 109         int r;
 110         __le64 value;
 111
 112         if (!info->current_index_set || !info->dirty)
 113                 return 0;
 114
 115         value = cpu_to_le64(info->current_bits);
 116
 117         __dm_bless_for_disk(&value);
 118         r = dm_array_set_value(&info->array_info, root, info->current_index,
 119                                &value, new_root);
 120         if (r)
 121                 return r;
 122
 123         info->current_index_set = false;
 124         info->dirty = false;
 125
 126         return 0;
 127 }
 128 EXPORT_SYMBOL_GPL(dm_bitset_flush);
 129
 130 static int read_bits(struct dm_disk_bitset *info, dm_block_t root,
 131                      uint32_t array_index)
 132 {
 133         int r;
 134         __le64 value;
 135
 136         r = dm_array_get_value(&info->array_info, root, array_index, &value);
 137         if (r)
 138                 return r;
 139
 140         info->current_bits = le64_to_cpu(value);
 141         info->current_index_set = true;
 142         info->current_index = array_index;
 143         info->dirty = false;
 144
 145         return 0;
 146 }
 147
 148 static int get_array_entry(struct dm_disk_bitset *info, dm_block_t root,
 149                            uint32_t index, dm_block_t *new_root)
 150 {
 151         int r;
 152         unsigned int array_index = index / BITS_PER_ARRAY_ENTRY;
 153
 154         if (info->current_index_set) {
 155                 if (info->current_index == array_index)
 156                         return 0;
 157
 158                 r = dm_bitset_flush(info, root, new_root);
 159                 if (r)
 160                         return r;
 161         }
 162
 163         return read_bits(info, root, array_index);
 164 }
 165
 166 int dm_bitset_set_bit(struct dm_disk_bitset *info, dm_block_t root,
 167                       uint32_t index, dm_block_t *new_root)
 168 {
 169         int r;
 170         unsigned int b = index % BITS_PER_ARRAY_ENTRY;
 171
 172         r = get_array_entry(info, root, index, new_root);
 173         if (r)
 174                 return r;
 175
 176         set_bit(b, (unsigned long *) &info->current_bits);
 177         info->dirty = true;
 178
 179         return 0;
 180 }
 181 EXPORT_SYMBOL_GPL(dm_bitset_set_bit);
 182
 183 int dm_bitset_clear_bit(struct dm_disk_bitset *info, dm_block_t root,
 184                         uint32_t index, dm_block_t *new_root)
 185 {
 186         int r;
 187         unsigned int b = index % BITS_PER_ARRAY_ENTRY;
 188
 189         r = get_array_entry(info, root, index, new_root);
 190         if (r)
 191                 return r;
 192
 193         clear_bit(b, (unsigned long *) &info->current_bits);
 194         info->dirty = true;
 195
 196         return 0;
 197 }
 198 EXPORT_SYMBOL_GPL(dm_bitset_clear_bit);
 199
 200 int dm_bitset_test_bit(struct dm_disk_bitset *info, dm_block_t root,
 201                        uint32_t index, dm_block_t *new_root, bool *result)
 202 {
 203         int r;
 204         unsigned int b = index % BITS_PER_ARRAY_ENTRY;
 205
 206         r = get_array_entry(info, root, index, new_root);
 207         if (r)
 208                 return r;
 209
 210         *result = test_bit(b, (unsigned long *) &info->current_bits);
 211         return 0;
 212 }
 213 EXPORT_SYMBOL_GPL(dm_bitset_test_bit);
 214
 215 static int cursor_next_array_entry(struct dm_bitset_cursor *c)
 216 {
 217         int r;
 218         __le64 *value;
 219
 220         r = dm_array_cursor_next(&c->cursor);
 221         if (r)
 222                 return r;
 223
 224         dm_array_cursor_get_value(&c->cursor, (void **) &value);
 225         c->array_index++;
 226         c->bit_index = 0;
 227         c->current_bits = le64_to_cpu(*value);
 228         return 0;
 229 }
 230
 231 int dm_bitset_cursor_begin(struct dm_disk_bitset *info,
 232                            dm_block_t root, uint32_t nr_entries,
 233                            struct dm_bitset_cursor *c)
 234 {
 235         int r;
 236         __le64 *value;
 237
 238         if (!nr_entries)
 239                 return -ENODATA;
 240
 241         c->info = info;
 242         c->entries_remaining = nr_entries;
 243
 244         r = dm_array_cursor_begin(&info->array_info, root, &c->cursor);
 245         if (r)
 246                 return r;
 247
 248         dm_array_cursor_get_value(&c->cursor, (void **) &value);
 249         c->array_index = 0;
 250         c->bit_index = 0;
 251         c->current_bits = le64_to_cpu(*value);
 252
 253         return r;
 254 }
 255 EXPORT_SYMBOL_GPL(dm_bitset_cursor_begin);
 256
 257 void dm_bitset_cursor_end(struct dm_bitset_cursor *c)
 258 {
 259         return dm_array_cursor_end(&c->cursor);
 260 }
 261 EXPORT_SYMBOL_GPL(dm_bitset_cursor_end);
 262
 263 int dm_bitset_cursor_next(struct dm_bitset_cursor *c)
 264 {
 265         int r = 0;
 266
 267         if (!c->entries_remaining)
 268                 return -ENODATA;
 269
 270         c->entries_remaining--;
 271         if (++c->bit_index > 63)
 272                 r = cursor_next_array_entry(c);
 273
 274         return r;
 275 }
 276 EXPORT_SYMBOL_GPL(dm_bitset_cursor_next);
 277
 278 int dm_bitset_cursor_skip(struct dm_bitset_cursor *c, uint32_t count)
 279 {
 280         int r;
 281         __le64 *value;
 282         uint32_t nr_array_skip;
 283         uint32_t remaining_in_word = 64 - c->bit_index;
 284
 285         if (c->entries_remaining < count)
 286                 return -ENODATA;
 287
 288         if (count < remaining_in_word) {
 289                 c->bit_index += count;
 290                 c->entries_remaining -= count;
 291                 return 0;
 292
 293         } else {
 294                 c->entries_remaining -= remaining_in_word;
 295                 count -= remaining_in_word;
 296         }
 297
 298         nr_array_skip = (count / 64) + 1;
 299         r = dm_array_cursor_skip(&c->cursor, nr_array_skip);
 300         if (r)
 301                 return r;
 302
 303         dm_array_cursor_get_value(&c->cursor, (void **) &value);
 304         c->entries_remaining -= count;
 305         c->array_index += nr_array_skip;
 306         c->bit_index = count & 63;
 307         c->current_bits = le64_to_cpu(*value);
 308
 309         return 0;
 310 }
 311 EXPORT_SYMBOL_GPL(dm_bitset_cursor_skip);
 312
 313 bool dm_bitset_cursor_get_value(struct dm_bitset_cursor *c)
 314 {
 315         return test_bit(c->bit_index, (unsigned long *) &c->current_bits);
 316 }
 317 EXPORT_SYMBOL_GPL(dm_bitset_cursor_get_value);
 318
 319 /*----------------------------------------------------------------*/