e2fsck/ea_refcount.c

   1 /*
   2  * ea_refcount.c
   3  *
   4  * Copyright (C) 2001 Theodore Ts'o.  This file may be
   5  * redistributed under the terms of the GNU Public License.
   6  */
   7
   8 #include "config.h"
   9 #if HAVE_UNISTD_H
  10 #include <unistd.h>
  11 #endif
  12 #include <string.h>
  13 #include <stdio.h>
  14
  15 #ifdef TEST_PROGRAM
  16 #undef ENABLE_NLS
  17 #endif
  18 #include "e2fsck.h"
  19
  20 /*
  21  * The strategy we use for keeping track of EA refcounts is as
  22  * follows.  We keep a sorted array of first EA blocks and its
  23  * reference counts.  Once the refcount has dropped to zero, it is
  24  * removed from the array to save memory space.  Once the EA block is
  25  * checked, its bit is set in the block_ea_map bitmap.
  26  */
  27 struct ea_refcount_el {
  28         /* ea_key could either be an inode number or block number. */
  29         ea_key_t        ea_key;
  30         ea_value_t      ea_value;
  31 };
  32
  33 struct ea_refcount {
  34         size_t          count;
  35         size_t          size;
  36         size_t          cursor;
  37         struct ea_refcount_el   *list;
  38 };
  39
  40 void ea_refcount_free(ext2_refcount_t refcount)
  41 {
  42         if (!refcount)
  43                 return;
  44
  45         if (refcount->list)
  46                 ext2fs_free_mem(&refcount->list);
  47         ext2fs_free_mem(&refcount);
  48 }
  49
  50 errcode_t ea_refcount_create(size_t size, ext2_refcount_t *ret)
  51 {
  52         ext2_refcount_t refcount;
  53         errcode_t       retval;
  54         size_t          bytes;
  55
  56         retval = ext2fs_get_mem(sizeof(struct ea_refcount), &refcount);
  57         if (retval)
  58                 return retval;
  59         memset(refcount, 0, sizeof(struct ea_refcount));
  60
  61         if (!size)
  62                 size = 500;
  63         refcount->size = size;
  64         bytes = size * sizeof(struct ea_refcount_el);
  65 #ifdef DEBUG
  66         printf("Refcount allocated %zu entries, %zu bytes.\n",
  67                refcount->size, bytes);
  68 #endif
  69         retval = ext2fs_get_mem(bytes, &refcount->list);
  70         if (retval)
  71                 goto errout;
  72         memset(refcount->list, 0, bytes);
  73
  74         refcount->count = 0;
  75         refcount->cursor = 0;
  76
  77         *ret = refcount;
  78         return 0;
  79
  80 errout:
  81         ea_refcount_free(refcount);
  82         return(retval);
  83 }
  84
  85 /*
  86  * collapse_refcount() --- go through the refcount array, and get rid
  87  * of any count == zero entries
  88  */
  89 static void refcount_collapse(ext2_refcount_t refcount)
  90 {
  91         unsigned int    i, j;
  92         struct ea_refcount_el   *list;
  93
  94         list = refcount->list;
  95         for (i = 0, j = 0; i < refcount->count; i++) {
  96                 if (list[i].ea_value) {
  97                         if (i != j)
  98                                 list[j] = list[i];
  99                         j++;
 100                 }
 101         }
 102 #if defined(DEBUG) || defined(TEST_PROGRAM)
 103         printf("Refcount_collapse: size was %zu, now %d\n",
 104                refcount->count, j);
 105 #endif
 106         refcount->count = j;
 107 }
 108
 109
 110 /*
 111  * insert_refcount_el() --- Insert a new entry into the sorted list at a
 112  *      specified position.
 113  */
 114 static struct ea_refcount_el *insert_refcount_el(ext2_refcount_t refcount,
 115                                                  ea_key_t ea_key, int pos)
 116 {
 117         struct ea_refcount_el   *el;
 118         errcode_t               retval;
 119         size_t                  new_size = 0;
 120         int                     num;
 121
 122         if (refcount->count >= refcount->size) {
 123                 new_size = refcount->size + 100;
 124 #ifdef DEBUG
 125                 printf("Reallocating refcount %d entries...\n", new_size);
 126 #endif
 127                 retval = ext2fs_resize_mem((size_t) refcount->size *
 128                                            sizeof(struct ea_refcount_el),
 129                                            (size_t) new_size *
 130                                            sizeof(struct ea_refcount_el),
 131                                            &refcount->list);
 132                 if (retval)
 133                         return 0;
 134                 refcount->size = new_size;
 135         }
 136         num = (int) refcount->count - pos;
 137         if (num < 0)
 138                 return 0;       /* should never happen */
 139         if (num) {
 140                 memmove(&refcount->list[pos+1], &refcount->list[pos],
 141                         sizeof(struct ea_refcount_el) * num);
 142         }
 143         refcount->count++;
 144         el = &refcount->list[pos];
 145         el->ea_key = ea_key;
 146         el->ea_value = 0;
 147         return el;
 148 }
 149
 150
 151 /*
 152  * get_refcount_el() --- given an block number, try to find refcount
 153  *      information in the sorted list.  If the create flag is set,
 154  *      and we can't find an entry, create one in the sorted list.
 155  */
 156 static struct ea_refcount_el *get_refcount_el(ext2_refcount_t refcount,
 157                                               ea_key_t ea_key, int create)
 158 {
 159         int     low, high, mid;
 160
 161         if (!refcount || !refcount->list)
 162                 return 0;
 163 retry:
 164         low = 0;
 165         high = (int) refcount->count-1;
 166         if (create && ((refcount->count == 0) ||
 167                        (ea_key > refcount->list[high].ea_key))) {
 168                 if (refcount->count >= refcount->size)
 169                         refcount_collapse(refcount);
 170
 171                 return insert_refcount_el(refcount, ea_key,
 172                                           (unsigned) refcount->count);
 173         }
 174         if (refcount->count == 0)
 175                 return 0;
 176
 177         if (refcount->cursor >= refcount->count)
 178                 refcount->cursor = 0;
 179         if (ea_key == refcount->list[refcount->cursor].ea_key)
 180                 return &refcount->list[refcount->cursor++];
 181 #ifdef DEBUG
 182         printf("Non-cursor get_refcount_el: %u\n", ea_key);
 183 #endif
 184         while (low <= high) {
 185                 mid = (low+high)/2;
 186                 if (ea_key == refcount->list[mid].ea_key) {
 187                         refcount->cursor = mid+1;
 188                         return &refcount->list[mid];
 189                 }
 190                 if (ea_key < refcount->list[mid].ea_key)
 191                         high = mid-1;
 192                 else
 193                         low = mid+1;
 194         }
 195         /*
 196          * If we need to create a new entry, it should be right at
 197          * low (where high will be left at low-1).
 198          */
 199         if (create) {
 200                 if (refcount->count >= refcount->size) {
 201                         refcount_collapse(refcount);
 202                         if (refcount->count < refcount->size)
 203                                 goto retry;
 204                 }
 205                 return insert_refcount_el(refcount, ea_key, low);
 206         }
 207         return 0;
 208 }
 209
 210 errcode_t ea_refcount_fetch(ext2_refcount_t refcount, ea_key_t ea_key,
 211                             ea_value_t *ret)
 212 {
 213         struct ea_refcount_el   *el;
 214
 215         el = get_refcount_el(refcount, ea_key, 0);
 216         if (!el) {
 217                 *ret = 0;
 218                 return 0;
 219         }
 220         *ret = el->ea_value;
 221         return 0;
 222 }
 223
 224 errcode_t ea_refcount_increment(ext2_refcount_t refcount, ea_key_t ea_key,
 225                                 ea_value_t *ret)
 226 {
 227         struct ea_refcount_el   *el;
 228
 229         el = get_refcount_el(refcount, ea_key, 1);
 230         if (!el)
 231                 return EXT2_ET_NO_MEMORY;
 232         el->ea_value++;
 233
 234         if (ret)
 235                 *ret = el->ea_value;
 236         return 0;
 237 }
 238
 239 errcode_t ea_refcount_decrement(ext2_refcount_t refcount, ea_key_t ea_key,
 240                                 ea_value_t *ret)
 241 {
 242         struct ea_refcount_el   *el;
 243
 244         el = get_refcount_el(refcount, ea_key, 0);
 245         if (!el || el->ea_value == 0)
 246                 return EXT2_ET_INVALID_ARGUMENT;
 247
 248         el->ea_value--;
 249
 250         if (ret)
 251                 *ret = el->ea_value;
 252         return 0;
 253 }
 254
 255 errcode_t ea_refcount_store(ext2_refcount_t refcount, ea_key_t ea_key,
 256                             ea_value_t ea_value)
 257 {
 258         struct ea_refcount_el   *el;
 259
 260         /*
 261          * Get the refcount element
 262          */
 263         el = get_refcount_el(refcount, ea_key, ea_value ? 1 : 0);
 264         if (!el)
 265                 return ea_value ? EXT2_ET_NO_MEMORY : 0;
 266         el->ea_value = ea_value;
 267         return 0;
 268 }
 269
 270 size_t ext2fs_get_refcount_size(ext2_refcount_t refcount)
 271 {
 272         if (!refcount)
 273                 return 0;
 274
 275         return refcount->size;
 276 }
 277
 278 void ea_refcount_intr_begin(ext2_refcount_t refcount)
 279 {
 280         refcount->cursor = 0;
 281 }
 282
 283 ea_key_t ea_refcount_intr_next(ext2_refcount_t refcount,
 284                                 ea_value_t *ret)
 285 {
 286         struct ea_refcount_el   *list;
 287
 288         while (1) {
 289                 if (refcount->cursor >= refcount->count)
 290                         return 0;
 291                 list = refcount->list;
 292                 if (list[refcount->cursor].ea_value) {
 293                         if (ret)
 294                                 *ret = list[refcount->cursor].ea_value;
 295                         return list[refcount->cursor++].ea_key;
 296                 }
 297                 refcount->cursor++;
 298         }
 299 }
 300
 301
 302 #ifdef TEST_PROGRAM
 303
 304 errcode_t ea_refcount_validate(ext2_refcount_t refcount, FILE *out)
 305 {
 306         errcode_t       ret = 0;
 307         int             i;
 308         const char *bad = "bad refcount";
 309
 310         if (refcount->count > refcount->size) {
 311                 fprintf(out, "%s: count > size\n", bad);
 312                 return EXT2_ET_INVALID_ARGUMENT;
 313         }
 314         for (i=1; i < refcount->count; i++) {
 315                 if (refcount->list[i-1].ea_key >= refcount->list[i].ea_key) {
 316                         fprintf(out,
 317                                 "%s: list[%d].ea_key=%llu, list[%d].ea_key=%llu\n",
 318                                 bad, i-1, refcount->list[i-1].ea_key, i,
 319                                 refcount->list[i].ea_key);
 320                         ret = EXT2_ET_INVALID_ARGUMENT;
 321                 }
 322         }
 323         return ret;
 324 }
 325
 326 #define BCODE_END       0
 327 #define BCODE_CREATE    1
 328 #define BCODE_FREE      2
 329 #define BCODE_STORE     3
 330 #define BCODE_INCR      4
 331 #define BCODE_DECR      5
 332 #define BCODE_FETCH     6
 333 #define BCODE_VALIDATE  7
 334 #define BCODE_LIST      8
 335 #define BCODE_COLLAPSE 9
 336
 337 int bcode_program[] = {
 338         BCODE_CREATE, 5,
 339         BCODE_STORE, 3, 3,
 340         BCODE_STORE, 4, 4,
 341         BCODE_STORE, 1, 1,
 342         BCODE_STORE, 8, 8,
 343         BCODE_STORE, 2, 2,
 344         BCODE_STORE, 4, 0,
 345         BCODE_STORE, 2, 0,
 346         BCODE_STORE, 6, 6,
 347         BCODE_VALIDATE,
 348         BCODE_STORE, 4, 4,
 349         BCODE_STORE, 2, 2,
 350         BCODE_FETCH, 1,
 351         BCODE_FETCH, 2,
 352         BCODE_INCR, 3,
 353         BCODE_INCR, 3,
 354         BCODE_DECR, 4,
 355         BCODE_STORE, 4, 4,
 356         BCODE_VALIDATE,
 357         BCODE_STORE, 20, 20,
 358         BCODE_STORE, 40, 40,
 359         BCODE_STORE, 30, 30,
 360         BCODE_STORE, 10, 10,
 361         BCODE_DECR, 30,
 362         BCODE_FETCH, 30,
 363         BCODE_DECR, 2,
 364         BCODE_DECR, 2,
 365         BCODE_COLLAPSE,
 366         BCODE_LIST,
 367         BCODE_VALIDATE,
 368         BCODE_FREE,
 369         BCODE_END
 370 };
 371
 372 int main(int argc, char **argv)
 373 {
 374         int     i = 0;
 375         ext2_refcount_t refcount;
 376         size_t          size;
 377         ea_key_t        ea_key;
 378         ea_value_t      arg;
 379         errcode_t       retval;
 380
 381         while (1) {
 382                 switch (bcode_program[i++]) {
 383                 case BCODE_END:
 384                         exit(0);
 385                 case BCODE_CREATE:
 386                         size = bcode_program[i++];
 387                         retval = ea_refcount_create(size, &refcount);
 388                         if (retval) {
 389                                 com_err("ea_refcount_create", retval,
 390                                         "while creating size %zu", size);
 391                                 exit(1);
 392                         } else
 393                                 printf("Creating refcount with size %zu\n",
 394                                        size);
 395                         break;
 396                 case BCODE_FREE:
 397                         ea_refcount_free(refcount);
 398                         refcount = 0;
 399                         printf("Freeing refcount\n");
 400                         break;
 401                 case BCODE_STORE:
 402                         ea_key = (size_t) bcode_program[i++];
 403                         arg = bcode_program[i++];
 404                         printf("Storing ea_key %llu with value %llu\n", ea_key,
 405                                arg);
 406                         retval = ea_refcount_store(refcount, ea_key, arg);
 407                         if (retval)
 408                                 com_err("ea_refcount_store", retval,
 409                                         "while storing ea_key %llu", ea_key);
 410                         break;
 411                 case BCODE_FETCH:
 412                         ea_key = (size_t) bcode_program[i++];
 413                         retval = ea_refcount_fetch(refcount, ea_key, &arg);
 414                         if (retval)
 415                                 com_err("ea_refcount_fetch", retval,
 416                                         "while fetching ea_key %llu", ea_key);
 417                         else
 418                                 printf("bcode_fetch(%llu) returns %llu\n",
 419                                        ea_key, arg);
 420                         break;
 421                 case BCODE_INCR:
 422                         ea_key = (size_t) bcode_program[i++];
 423                         retval = ea_refcount_increment(refcount, ea_key, &arg);
 424                         if (retval)
 425                                 com_err("ea_refcount_increment", retval,
 426                                         "while incrementing ea_key %llu",
 427                                         ea_key);
 428                         else
 429                                 printf("bcode_increment(%llu) returns %llu\n",
 430                                        ea_key, arg);
 431                         break;
 432                 case BCODE_DECR:
 433                         ea_key = (size_t) bcode_program[i++];
 434                         retval = ea_refcount_decrement(refcount, ea_key, &arg);
 435                         if (retval)
 436                                 com_err("ea_refcount_decrement", retval,
 437                                         "while decrementing ea_key %llu",
 438                                         ea_key);
 439                         else
 440                                 printf("bcode_decrement(%llu) returns %llu\n",
 441                                        ea_key, arg);
 442                         break;
 443                 case BCODE_VALIDATE:
 444                         retval = ea_refcount_validate(refcount, stderr);
 445                         if (retval)
 446                                 com_err("ea_refcount_validate", retval,
 447                                         "while validating");
 448                         else
 449                                 printf("Refcount validation OK.\n");
 450                         break;
 451                 case BCODE_LIST:
 452                         ea_refcount_intr_begin(refcount);
 453                         while (1) {
 454                                 ea_key = ea_refcount_intr_next(refcount, &arg);
 455                                 if (!ea_key)
 456                                         break;
 457                                 printf("\tea_key=%llu, count=%llu\n", ea_key,
 458                                        arg);
 459                         }
 460                         break;
 461                 case BCODE_COLLAPSE:
 462                         refcount_collapse(refcount);
 463                         break;
 464                 }
 465
 466         }
 467 }
 468
 469 #endif