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