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_memzero(sizeof(struct ea_refcount), &refcount);
  57         if (retval)
  58                 return retval;
  59
  60         if (!size)
  61                 size = 500;
  62         refcount->size = size;
  63         bytes = size * sizeof(struct ea_refcount_el);
  64 #ifdef DEBUG
  65         printf("Refcount allocated %zu entries, %zu bytes.\n",
  66                refcount->size, bytes);
  67 #endif
  68         retval = ext2fs_get_memzero(bytes, &refcount->list);
  69         if (retval)
  70                 goto errout;
  71
  72         refcount->count = 0;
  73         refcount->cursor = 0;
  74
  75         *ret = refcount;
  76         return 0;
  77
  78 errout:
  79         ea_refcount_free(refcount);
  80         return(retval);
  81 }
  82
  83 /*
  84  * collapse_refcount() --- go through the refcount array, and get rid
  85  * of any count == zero entries
  86  */
  87 static void refcount_collapse(ext2_refcount_t refcount)
  88 {
  89         unsigned int    i, j;
  90         struct ea_refcount_el   *list;
  91
  92         list = refcount->list;
  93         for (i = 0, j = 0; i < refcount->count; i++) {
  94                 if (list[i].ea_value) {
  95                         if (i != j)
  96                                 list[j] = list[i];
  97                         j++;
  98                 }
  99         }
 100 #if defined(DEBUG) || defined(TEST_PROGRAM)
 101         printf("Refcount_collapse: size was %zu, now %d\n",
 102                refcount->count, j);
 103 #endif
 104         refcount->count = j;
 105 }
 106
 107
 108 /*
 109  * insert_refcount_el() --- Insert a new entry into the sorted list at a
 110  *      specified position.
 111  */
 112 static struct ea_refcount_el *insert_refcount_el(ext2_refcount_t refcount,
 113                                                  ea_key_t ea_key, int pos)
 114 {
 115         struct ea_refcount_el   *el;
 116         errcode_t               retval;
 117         size_t                  new_size = 0;
 118         int                     num;
 119
 120         if (refcount->count >= refcount->size) {
 121                 new_size = refcount->size + 100;
 122 #ifdef DEBUG
 123                 printf("Reallocating refcount %d entries...\n", new_size);
 124 #endif
 125                 retval = ext2fs_resize_mem((size_t) refcount->size *
 126                                            sizeof(struct ea_refcount_el),
 127                                            (size_t) new_size *
 128                                            sizeof(struct ea_refcount_el),
 129                                            &refcount->list);
 130                 if (retval)
 131                         return 0;
 132                 refcount->size = new_size;
 133         }
 134         num = (int) refcount->count - pos;
 135         if (num < 0)
 136                 return 0;       /* should never happen */
 137         if (num) {
 138                 memmove(&refcount->list[pos+1], &refcount->list[pos],
 139                         sizeof(struct ea_refcount_el) * num);
 140         }
 141         refcount->count++;
 142         el = &refcount->list[pos];
 143         el->ea_key = ea_key;
 144         el->ea_value = 0;
 145         return el;
 146 }
 147
 148
 149 /*
 150  * get_refcount_el() --- given an block number, try to find refcount
 151  *      information in the sorted list.  If the create flag is set,
 152  *      and we can't find an entry, create one in the sorted list.
 153  */
 154 static struct ea_refcount_el *get_refcount_el(ext2_refcount_t refcount,
 155                                               ea_key_t ea_key, int create)
 156 {
 157         int     low, high, mid;
 158
 159         if (!refcount || !refcount->list)
 160                 return 0;
 161 retry:
 162         low = 0;
 163         high = (int) refcount->count-1;
 164         if (create && ((refcount->count == 0) ||
 165                        (ea_key > refcount->list[high].ea_key))) {
 166                 if (refcount->count >= refcount->size)
 167                         refcount_collapse(refcount);
 168
 169                 return insert_refcount_el(refcount, ea_key,
 170                                           (unsigned) refcount->count);
 171         }
 172         if (refcount->count == 0)
 173                 return 0;
 174
 175         if (refcount->cursor >= refcount->count)
 176                 refcount->cursor = 0;
 177         if (ea_key == refcount->list[refcount->cursor].ea_key)
 178                 return &refcount->list[refcount->cursor++];
 179 #ifdef DEBUG
 180         printf("Non-cursor get_refcount_el: %u\n", ea_key);
 181 #endif
 182         while (low <= high) {
 183                 mid = (low+high)/2;
 184                 if (ea_key == refcount->list[mid].ea_key) {
 185                         refcount->cursor = mid+1;
 186                         return &refcount->list[mid];
 187                 }
 188                 if (ea_key < refcount->list[mid].ea_key)
 189                         high = mid-1;
 190                 else
 191                         low = mid+1;
 192         }
 193         /*
 194          * If we need to create a new entry, it should be right at
 195          * low (where high will be left at low-1).
 196          */
 197         if (create) {
 198                 if (refcount->count >= refcount->size) {
 199                         refcount_collapse(refcount);
 200                         if (refcount->count < refcount->size)
 201                                 goto retry;
 202                 }
 203                 return insert_refcount_el(refcount, ea_key, low);
 204         }
 205         return 0;
 206 }
 207
 208 errcode_t ea_refcount_fetch(ext2_refcount_t refcount, ea_key_t ea_key,
 209                             ea_value_t *ret)
 210 {
 211         struct ea_refcount_el   *el;
 212
 213         el = get_refcount_el(refcount, ea_key, 0);
 214         if (!el) {
 215                 *ret = 0;
 216                 return 0;
 217         }
 218         *ret = el->ea_value;
 219         return 0;
 220 }
 221
 222 errcode_t ea_refcount_increment(ext2_refcount_t refcount, ea_key_t ea_key,
 223                                 ea_value_t *ret)
 224 {
 225         struct ea_refcount_el   *el;
 226
 227         el = get_refcount_el(refcount, ea_key, 1);
 228         if (!el)
 229                 return EXT2_ET_NO_MEMORY;
 230         el->ea_value++;
 231
 232         if (ret)
 233                 *ret = el->ea_value;
 234         return 0;
 235 }
 236
 237 errcode_t ea_refcount_decrement(ext2_refcount_t refcount, ea_key_t ea_key,
 238                                 ea_value_t *ret)
 239 {
 240         struct ea_refcount_el   *el;
 241
 242         el = get_refcount_el(refcount, ea_key, 0);
 243         if (!el || el->ea_value == 0)
 244                 return EXT2_ET_INVALID_ARGUMENT;
 245
 246         el->ea_value--;
 247
 248         if (ret)
 249                 *ret = el->ea_value;
 250         return 0;
 251 }
 252
 253 errcode_t ea_refcount_store(ext2_refcount_t refcount, ea_key_t ea_key,
 254                             ea_value_t ea_value)
 255 {
 256         struct ea_refcount_el   *el;
 257
 258         /*
 259          * Get the refcount element
 260          */
 261         el = get_refcount_el(refcount, ea_key, ea_value ? 1 : 0);
 262         if (!el)
 263                 return ea_value ? EXT2_ET_NO_MEMORY : 0;
 264         el->ea_value = ea_value;
 265         return 0;
 266 }
 267
 268 size_t ext2fs_get_refcount_size(ext2_refcount_t refcount)
 269 {
 270         if (!refcount)
 271                 return 0;
 272
 273         return refcount->size;
 274 }
 275
 276 void ea_refcount_intr_begin(ext2_refcount_t refcount)
 277 {
 278         refcount->cursor = 0;
 279 }
 280
 281 ea_key_t ea_refcount_intr_next(ext2_refcount_t refcount,
 282                                 ea_value_t *ret)
 283 {
 284         struct ea_refcount_el   *list;
 285
 286         while (1) {
 287                 if (refcount->cursor >= refcount->count)
 288                         return 0;
 289                 list = refcount->list;
 290                 if (list[refcount->cursor].ea_value) {
 291                         if (ret)
 292                                 *ret = list[refcount->cursor].ea_value;
 293                         return list[refcount->cursor++].ea_key;
 294                 }
 295                 refcount->cursor++;
 296         }
 297 }
 298
 299
 300 #ifdef TEST_PROGRAM
 301
 302 errcode_t ea_refcount_validate(ext2_refcount_t refcount, FILE *out)
 303 {
 304         errcode_t       ret = 0;
 305         int             i;
 306         const char *bad = "bad refcount";
 307
 308         if (refcount->count > refcount->size) {
 309                 fprintf(out, "%s: count > size\n", bad);
 310                 return EXT2_ET_INVALID_ARGUMENT;
 311         }
 312         for (i=1; i < refcount->count; i++) {
 313                 if (refcount->list[i-1].ea_key >= refcount->list[i].ea_key) {
 314                         fprintf(out,
 315                                 "%s: list[%d].ea_key=%llu, list[%d].ea_key=%llu\n",
 316                                 bad, i-1,
 317                                 (unsigned long long) refcount->list[i-1].ea_key,
 318                                 i,
 319                                 (unsigned long long) 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",
 405                                (unsigned long long) ea_key,
 406                                (unsigned long long) arg);
 407                         retval = ea_refcount_store(refcount, ea_key, arg);
 408                         if (retval)
 409                                 com_err("ea_refcount_store", retval,
 410                                         "while storing ea_key %llu",
 411                                         (unsigned long long) ea_key);
 412                         break;
 413                 case BCODE_FETCH:
 414                         ea_key = (size_t) bcode_program[i++];
 415                         retval = ea_refcount_fetch(refcount, ea_key, &arg);
 416                         if (retval)
 417                                 com_err("ea_refcount_fetch", retval,
 418                                         "while fetching ea_key %llu",
 419                                         (unsigned long long) ea_key);
 420                         else
 421                                 printf("bcode_fetch(%llu) returns %llu\n",
 422                                        (unsigned long long) ea_key,
 423                                        (unsigned long long) arg);
 424                         break;
 425                 case BCODE_INCR:
 426                         ea_key = (size_t) bcode_program[i++];
 427                         retval = ea_refcount_increment(refcount, ea_key, &arg);
 428                         if (retval)
 429                                 com_err("ea_refcount_increment", retval,
 430                                         "while incrementing ea_key %llu",
 431                                         (unsigned long long) ea_key);
 432                         else
 433                                 printf("bcode_increment(%llu) returns %llu\n",
 434                                        (unsigned long long) ea_key,
 435                                        (unsigned long long) arg);
 436                         break;
 437                 case BCODE_DECR:
 438                         ea_key = (size_t) bcode_program[i++];
 439                         retval = ea_refcount_decrement(refcount, ea_key, &arg);
 440                         if (retval)
 441                                 com_err("ea_refcount_decrement", retval,
 442                                         "while decrementing ea_key %llu",
 443                                         (unsigned long long) ea_key);
 444                         else
 445                                 printf("bcode_decrement(%llu) returns %llu\n",
 446                                        (unsigned long long) ea_key,
 447                                        (unsigned long long) arg);
 448                         break;
 449                 case BCODE_VALIDATE:
 450                         retval = ea_refcount_validate(refcount, stderr);
 451                         if (retval)
 452                                 com_err("ea_refcount_validate", retval,
 453                                         "while validating");
 454                         else
 455                                 printf("Refcount validation OK.\n");
 456                         break;
 457                 case BCODE_LIST:
 458                         ea_refcount_intr_begin(refcount);
 459                         while (1) {
 460                                 ea_key = ea_refcount_intr_next(refcount, &arg);
 461                                 if (!ea_key)
 462                                         break;
 463                                 printf("\tea_key=%llu, count=%llu\n",
 464                                        (unsigned long long) ea_key,
 465                                        (unsigned long long) arg);
 466                         }
 467                         break;
 468                 case BCODE_COLLAPSE:
 469                         refcount_collapse(refcount);
 470                         break;
 471                 }
 472
 473         }
 474 }
 475
 476 #endif