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         blk_t   ea_blk;
  29         int     ea_count;
  30 };
  31
  32 struct ea_refcount {
  33         blk_t           count;
  34         blk_t           size;
  35         blk_t           cursor;
  36         struct ea_refcount_el   *list;
  37 };
  38
  39 void ea_refcount_free(ext2_refcount_t refcount)
  40 {
  41         if (!refcount)
  42                 return;
  43
  44         if (refcount->list)
  45                 ext2fs_free_mem(&refcount->list);
  46         ext2fs_free_mem(&refcount);
  47 }
  48
  49 errcode_t ea_refcount_create(int size, ext2_refcount_t *ret)
  50 {
  51         ext2_refcount_t refcount;
  52         errcode_t       retval;
  53         size_t          bytes;
  54
  55         retval = ext2fs_get_mem(sizeof(struct ea_refcount), &refcount);
  56         if (retval)
  57                 return retval;
  58         memset(refcount, 0, sizeof(struct ea_refcount));
  59
  60         if (!size)
  61                 size = 500;
  62         refcount->size = size;
  63         bytes = (size_t) (size * sizeof(struct ea_refcount_el));
  64 #ifdef DEBUG
  65         printf("Refcount allocated %d entries, %d bytes.\n",
  66                refcount->size, bytes);
  67 #endif
  68         retval = ext2fs_get_mem(bytes, &refcount->list);
  69         if (retval)
  70                 goto errout;
  71         memset(refcount->list, 0, bytes);
  72
  73         refcount->count = 0;
  74         refcount->cursor = 0;
  75
  76         *ret = refcount;
  77         return 0;
  78
  79 errout:
  80         ea_refcount_free(refcount);
  81         return(retval);
  82 }
  83
  84 /*
  85  * collapse_refcount() --- go through the refcount array, and get rid
  86  * of any count == zero entries
  87  */
  88 static void refcount_collapse(ext2_refcount_t refcount)
  89 {
  90         unsigned int    i, j;
  91         struct ea_refcount_el   *list;
  92
  93         list = refcount->list;
  94         for (i = 0, j = 0; i < refcount->count; i++) {
  95                 if (list[i].ea_count) {
  96                         if (i != j)
  97                                 list[j] = list[i];
  98                         j++;
  99                 }
 100         }
 101 #if defined(DEBUG) || defined(TEST_PROGRAM)
 102         printf("Refcount_collapse: size was %d, now %d\n",
 103                refcount->count, j);
 104 #endif
 105         refcount->count = j;
 106 }
 107
 108
 109 /*
 110  * insert_refcount_el() --- Insert a new entry into the sorted list at a
 111  *      specified position.
 112  */
 113 static struct ea_refcount_el *insert_refcount_el(ext2_refcount_t refcount,
 114                                                  blk_t blk, int pos)
 115 {
 116         struct ea_refcount_el   *el;
 117         errcode_t               retval;
 118         blk_t                   new_size = 0;
 119         int                     num;
 120
 121         if (refcount->count >= refcount->size) {
 122                 new_size = refcount->size + 100;
 123 #ifdef DEBUG
 124                 printf("Reallocating refcount %d entries...\n", new_size);
 125 #endif
 126                 retval = ext2fs_resize_mem((size_t) refcount->size *
 127                                            sizeof(struct ea_refcount_el),
 128                                            (size_t) new_size *
 129                                            sizeof(struct ea_refcount_el),
 130                                            &refcount->list);
 131                 if (retval)
 132                         return 0;
 133                 refcount->size = new_size;
 134         }
 135         num = (int) refcount->count - pos;
 136         if (num < 0)
 137                 return 0;       /* should never happen */
 138         if (num) {
 139                 memmove(&refcount->list[pos+1], &refcount->list[pos],
 140                         sizeof(struct ea_refcount_el) * num);
 141         }
 142         refcount->count++;
 143         el = &refcount->list[pos];
 144         el->ea_count = 0;
 145         el->ea_blk = blk;
 146         return el;
 147 }
 148
 149
 150 /*
 151  * get_refcount_el() --- given an block number, try to find refcount
 152  *      information in the sorted list.  If the create flag is set,
 153  *      and we can't find an entry, create one in the sorted list.
 154  */
 155 static struct ea_refcount_el *get_refcount_el(ext2_refcount_t refcount,
 156                                               blk_t blk, int create)
 157 {
 158         float   range;
 159         int     low, high, mid;
 160         blk_t   lowval, highval;
 161
 162         if (!refcount || !refcount->list)
 163                 return 0;
 164 retry:
 165         low = 0;
 166         high = (int) refcount->count-1;
 167         if (create && ((refcount->count == 0) ||
 168                        (blk > refcount->list[high].ea_blk))) {
 169                 if (refcount->count >= refcount->size)
 170                         refcount_collapse(refcount);
 171
 172                 return insert_refcount_el(refcount, blk,
 173                                           (unsigned) refcount->count);
 174         }
 175         if (refcount->count == 0)
 176                 return 0;
 177
 178         if (refcount->cursor >= refcount->count)
 179                 refcount->cursor = 0;
 180         if (blk == refcount->list[refcount->cursor].ea_blk)
 181                 return &refcount->list[refcount->cursor++];
 182 #ifdef DEBUG
 183         printf("Non-cursor get_refcount_el: %u\n", blk);
 184 #endif
 185         while (low <= high) {
 186 #if 0
 187                 mid = (low+high)/2;
 188 #else
 189                 if (low == high)
 190                         mid = low;
 191                 else {
 192                         /* Interpolate for efficiency */
 193                         lowval = refcount->list[low].ea_blk;
 194                         highval = refcount->list[high].ea_blk;
 195
 196                         if (blk < lowval)
 197                                 range = 0;
 198                         else if (blk > highval)
 199                                 range = 1;
 200                         else {
 201                                 range = ((float) (blk - lowval)) /
 202                                         (highval - lowval);
 203                                 if (range > 0.9)
 204                                         range = 0.9;
 205                                 if (range < 0.1)
 206                                         range = 0.1;
 207                         }
 208                         mid = low + ((int) (range * (high-low)));
 209                 }
 210 #endif
 211                 if (blk == refcount->list[mid].ea_blk) {
 212                         refcount->cursor = mid+1;
 213                         return &refcount->list[mid];
 214                 }
 215                 if (blk < refcount->list[mid].ea_blk)
 216                         high = mid-1;
 217                 else
 218                         low = mid+1;
 219         }
 220         /*
 221          * If we need to create a new entry, it should be right at
 222          * low (where high will be left at low-1).
 223          */
 224         if (create) {
 225                 if (refcount->count >= refcount->size) {
 226                         refcount_collapse(refcount);
 227                         if (refcount->count < refcount->size)
 228                                 goto retry;
 229                 }
 230                 return insert_refcount_el(refcount, blk, low);
 231         }
 232         return 0;
 233 }
 234
 235 errcode_t ea_refcount_fetch(ext2_refcount_t refcount, blk_t blk,
 236                                 int *ret)
 237 {
 238         struct ea_refcount_el   *el;
 239
 240         el = get_refcount_el(refcount, blk, 0);
 241         if (!el) {
 242                 *ret = 0;
 243                 return 0;
 244         }
 245         *ret = el->ea_count;
 246         return 0;
 247 }
 248
 249 errcode_t ea_refcount_increment(ext2_refcount_t refcount, blk_t blk, int *ret)
 250 {
 251         struct ea_refcount_el   *el;
 252
 253         el = get_refcount_el(refcount, blk, 1);
 254         if (!el)
 255                 return EXT2_ET_NO_MEMORY;
 256         el->ea_count++;
 257
 258         if (ret)
 259                 *ret = el->ea_count;
 260         return 0;
 261 }
 262
 263 errcode_t ea_refcount_decrement(ext2_refcount_t refcount, blk_t blk, int *ret)
 264 {
 265         struct ea_refcount_el   *el;
 266
 267         el = get_refcount_el(refcount, blk, 0);
 268         if (!el || el->ea_count == 0)
 269                 return EXT2_ET_INVALID_ARGUMENT;
 270
 271         el->ea_count--;
 272
 273         if (ret)
 274                 *ret = el->ea_count;
 275         return 0;
 276 }
 277
 278 errcode_t ea_refcount_store(ext2_refcount_t refcount, blk_t blk, int count)
 279 {
 280         struct ea_refcount_el   *el;
 281
 282         /*
 283          * Get the refcount element
 284          */
 285         el = get_refcount_el(refcount, blk, count ? 1 : 0);
 286         if (!el)
 287                 return count ? EXT2_ET_NO_MEMORY : 0;
 288         el->ea_count = count;
 289         return 0;
 290 }
 291
 292 blk_t ext2fs_get_refcount_size(ext2_refcount_t refcount)
 293 {
 294         if (!refcount)
 295                 return 0;
 296
 297         return refcount->size;
 298 }
 299
 300 void ea_refcount_intr_begin(ext2_refcount_t refcount)
 301 {
 302         refcount->cursor = 0;
 303 }
 304
 305
 306 blk_t ea_refcount_intr_next(ext2_refcount_t refcount,
 307                                 int *ret)
 308 {
 309         struct ea_refcount_el   *list;
 310
 311         while (1) {
 312                 if (refcount->cursor >= refcount->count)
 313                         return 0;
 314                 list = refcount->list;
 315                 if (list[refcount->cursor].ea_count) {
 316                         if (ret)
 317                                 *ret = list[refcount->cursor].ea_count;
 318                         return list[refcount->cursor++].ea_blk;
 319                 }
 320                 refcount->cursor++;
 321         }
 322 }
 323
 324
 325 #ifdef TEST_PROGRAM
 326
 327 errcode_t ea_refcount_validate(ext2_refcount_t refcount, FILE *out)
 328 {
 329         errcode_t       ret = 0;
 330         int             i;
 331         const char *bad = "bad refcount";
 332
 333         if (refcount->count > refcount->size) {
 334                 fprintf(out, "%s: count > size\n", bad);
 335                 return EXT2_ET_INVALID_ARGUMENT;
 336         }
 337         for (i=1; i < refcount->count; i++) {
 338                 if (refcount->list[i-1].ea_blk >= refcount->list[i].ea_blk) {
 339                         fprintf(out, "%s: list[%d].blk=%u, list[%d].blk=%u\n",
 340                                 bad, i-1, refcount->list[i-1].ea_blk,
 341                                 i, refcount->list[i].ea_blk);
 342                         ret = EXT2_ET_INVALID_ARGUMENT;
 343                 }
 344         }
 345         return ret;
 346 }
 347
 348 #define BCODE_END       0
 349 #define BCODE_CREATE    1
 350 #define BCODE_FREE      2
 351 #define BCODE_STORE     3
 352 #define BCODE_INCR      4
 353 #define BCODE_DECR      5
 354 #define BCODE_FETCH     6
 355 #define BCODE_VALIDATE  7
 356 #define BCODE_LIST      8
 357 #define BCODE_COLLAPSE 9
 358
 359 int bcode_program[] = {
 360         BCODE_CREATE, 5,
 361         BCODE_STORE, 3, 3,
 362         BCODE_STORE, 4, 4,
 363         BCODE_STORE, 1, 1,
 364         BCODE_STORE, 8, 8,
 365         BCODE_STORE, 2, 2,
 366         BCODE_STORE, 4, 0,
 367         BCODE_STORE, 2, 0,
 368         BCODE_STORE, 6, 6,
 369         BCODE_VALIDATE,
 370         BCODE_STORE, 4, 4,
 371         BCODE_STORE, 2, 2,
 372         BCODE_FETCH, 1,
 373         BCODE_FETCH, 2,
 374         BCODE_INCR, 3,
 375         BCODE_INCR, 3,
 376         BCODE_DECR, 4,
 377         BCODE_STORE, 4, 4,
 378         BCODE_VALIDATE,
 379         BCODE_STORE, 20, 20,
 380         BCODE_STORE, 40, 40,
 381         BCODE_STORE, 30, 30,
 382         BCODE_STORE, 10, 10,
 383         BCODE_DECR, 30,
 384         BCODE_FETCH, 30,
 385         BCODE_DECR, 2,
 386         BCODE_DECR, 2,
 387         BCODE_COLLAPSE,
 388         BCODE_LIST,
 389         BCODE_VALIDATE,
 390         BCODE_FREE,
 391         BCODE_END
 392 };
 393
 394 int main(int argc, char **argv)
 395 {
 396         int     i = 0;
 397         ext2_refcount_t refcount;
 398         int             size, arg;
 399         blk_t           blk;
 400         errcode_t       retval;
 401
 402         while (1) {
 403                 switch (bcode_program[i++]) {
 404                 case BCODE_END:
 405                         exit(0);
 406                 case BCODE_CREATE:
 407                         size = bcode_program[i++];
 408                         retval = ea_refcount_create(size, &refcount);
 409                         if (retval) {
 410                                 com_err("ea_refcount_create",
 411                                         retval, "");
 412                                 exit(1);
 413                         } else
 414                                 printf("Creating refcount with size %d\n",
 415                                        size);
 416                         break;
 417                 case BCODE_FREE:
 418                         ea_refcount_free(refcount);
 419                         refcount = 0;
 420                         printf("Freeing refcount\n");
 421                         break;
 422                 case BCODE_STORE:
 423                         blk = (blk_t) bcode_program[i++];
 424                         arg = bcode_program[i++];
 425                         retval = ea_refcount_store(refcount, blk, arg);
 426                         printf("Storing blk %u with value %d\n", blk, arg);
 427                         if (retval)
 428                                 com_err("ea_refcount_store", retval, "");
 429                         break;
 430                 case BCODE_FETCH:
 431                         blk = (blk_t) bcode_program[i++];
 432                         retval = ea_refcount_fetch(refcount, blk, &arg);
 433                         if (retval)
 434                                 com_err("ea_refcount_fetch", retval, "");
 435                         else
 436                                 printf("bcode_fetch(%u) returns %d\n",
 437                                        blk, arg);
 438                         break;
 439                 case BCODE_INCR:
 440                         blk = (blk_t) bcode_program[i++];
 441                         retval = ea_refcount_increment(refcount, blk,
 442                                                            &arg);
 443                         if (retval)
 444                                 com_err("ea_refcount_increment", retval,
 445                                         "");
 446                         else
 447                                 printf("bcode_increment(%u) returns %d\n",
 448                                        blk, arg);
 449                         break;
 450                 case BCODE_DECR:
 451                         blk = (blk_t) bcode_program[i++];
 452                         retval = ea_refcount_decrement(refcount, blk,
 453                                                            &arg);
 454                         if (retval)
 455                                 com_err("ea_refcount_decrement", retval,
 456                                         "while decrementing blk %u", blk);
 457                         else
 458                                 printf("bcode_decrement(%u) returns %d\n",
 459                                        blk, arg);
 460                         break;
 461                 case BCODE_VALIDATE:
 462                         retval = ea_refcount_validate(refcount, stderr);
 463                         if (retval)
 464                                 com_err("ea_refcount_validate",
 465                                         retval, "");
 466                         else
 467                                 printf("Refcount validation OK.\n");
 468                         break;
 469                 case BCODE_LIST:
 470                         ea_refcount_intr_begin(refcount);
 471                         while (1) {
 472                                 blk = ea_refcount_intr_next(refcount,
 473                                                                 &arg);
 474                                 if (!blk)
 475                                         break;
 476                                 printf("\tblk=%u, count=%d\n", blk,
 477                                        arg);
 478                         }
 479                         break;
 480                 case BCODE_COLLAPSE:
 481                         refcount_collapse(refcount);
 482                         break;
 483                 }
 484
 485         }
 486 }
 487
 488 #endif