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 #if HAVE_UNISTD_H
   9 #include <unistd.h>
  10 #endif
  11 #include <string.h>
  12 #include <stdio.h>
  13
  14 #ifdef TEST_PROGRAM
  15 #undef ENABLE_NLS
  16 #endif
  17 #include "e2fsck.h"
  18
  19 /*
  20  * The strategy we use for keeping track of EA refcounts is as
  21  * follows.  We keep a sorted array of first EA blocks and its
  22  * reference counts.  Once the refcount has dropped to zero, it is
  23  * removed from the array to save memory space.  Once the EA block is
  24  * checked, its bit is set in the block_ea_map bitmap.
  25  */
  26 struct ea_refcount_el {
  27         blk64_t ea_blk;
  28         int     ea_count;
  29 };
  30
  31 struct ea_refcount {
  32         blk_t           count;
  33         blk_t           size;
  34         blk_t           cursor;
  35         struct ea_refcount_el   *list;
  36 };
  37
  38 void ea_refcount_free(ext2_refcount_t refcount)
  39 {
  40         if (!refcount)
  41                 return;
  42
  43         if (refcount->list)
  44                 ext2fs_free_mem(&refcount->list);
  45         ext2fs_free_mem(&refcount);
  46 }
  47
  48 errcode_t ea_refcount_create(int size, ext2_refcount_t *ret)
  49 {
  50         ext2_refcount_t refcount;
  51         errcode_t       retval;
  52         size_t          bytes;
  53
  54         retval = ext2fs_get_mem(sizeof(struct ea_refcount), &refcount);
  55         if (retval)
  56                 return retval;
  57         memset(refcount, 0, sizeof(struct ea_refcount));
  58
  59         if (!size)
  60                 size = 500;
  61         refcount->size = size;
  62         bytes = (size_t) (size * sizeof(struct ea_refcount_el));
  63 #ifdef DEBUG
  64         printf("Refcount allocated %d entries, %d bytes.\n",
  65                refcount->size, bytes);
  66 #endif
  67         retval = ext2fs_get_mem(bytes, &refcount->list);
  68         if (retval)
  69                 goto errout;
  70         memset(refcount->list, 0, bytes);
  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_count) {
  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 %d, 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                                                  blk64_t blk, int pos)
 114 {
 115         struct ea_refcount_el   *el;
 116         errcode_t               retval;
 117         blk_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_count = 0;
 144         el->ea_blk = blk;
 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                                               blk64_t blk, 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                        (blk > refcount->list[high].ea_blk))) {
 166                 if (refcount->count >= refcount->size)
 167                         refcount_collapse(refcount);
 168
 169                 return insert_refcount_el(refcount, blk,
 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 (blk == refcount->list[refcount->cursor].ea_blk)
 178                 return &refcount->list[refcount->cursor++];
 179 #ifdef DEBUG
 180         printf("Non-cursor get_refcount_el: %u\n", blk);
 181 #endif
 182         while (low <= high) {
 183                 mid = (low+high)/2;
 184                 if (blk == refcount->list[mid].ea_blk) {
 185                         refcount->cursor = mid+1;
 186                         return &refcount->list[mid];
 187                 }
 188                 if (blk < refcount->list[mid].ea_blk)
 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, blk, low);
 204         }
 205         return 0;
 206 }
 207
 208 errcode_t ea_refcount_fetch(ext2_refcount_t refcount, blk64_t blk,
 209                                 int *ret)
 210 {
 211         struct ea_refcount_el   *el;
 212
 213         el = get_refcount_el(refcount, blk, 0);
 214         if (!el) {
 215                 *ret = 0;
 216                 return 0;
 217         }
 218         *ret = el->ea_count;
 219         return 0;
 220 }
 221
 222 errcode_t ea_refcount_increment(ext2_refcount_t refcount, blk64_t blk, int *ret)
 223 {
 224         struct ea_refcount_el   *el;
 225
 226         el = get_refcount_el(refcount, blk, 1);
 227         if (!el)
 228                 return EXT2_ET_NO_MEMORY;
 229         el->ea_count++;
 230
 231         if (ret)
 232                 *ret = el->ea_count;
 233         return 0;
 234 }
 235
 236 errcode_t ea_refcount_decrement(ext2_refcount_t refcount, blk64_t blk, int *ret)
 237 {
 238         struct ea_refcount_el   *el;
 239
 240         el = get_refcount_el(refcount, blk, 0);
 241         if (!el || el->ea_count == 0)
 242                 return EXT2_ET_INVALID_ARGUMENT;
 243
 244         el->ea_count--;
 245
 246         if (ret)
 247                 *ret = el->ea_count;
 248         return 0;
 249 }
 250
 251 errcode_t ea_refcount_store(ext2_refcount_t refcount, blk64_t blk, int count)
 252 {
 253         struct ea_refcount_el   *el;
 254
 255         /*
 256          * Get the refcount element
 257          */
 258         el = get_refcount_el(refcount, blk, count ? 1 : 0);
 259         if (!el)
 260                 return count ? EXT2_ET_NO_MEMORY : 0;
 261         el->ea_count = count;
 262         return 0;
 263 }
 264
 265 blk_t ext2fs_get_refcount_size(ext2_refcount_t refcount)
 266 {
 267         if (!refcount)
 268                 return 0;
 269
 270         return refcount->size;
 271 }
 272
 273 void ea_refcount_intr_begin(ext2_refcount_t refcount)
 274 {
 275         refcount->cursor = 0;
 276 }
 277
 278
 279 blk64_t ea_refcount_intr_next(ext2_refcount_t refcount,
 280                                 int *ret)
 281 {
 282         struct ea_refcount_el   *list;
 283
 284         while (1) {
 285                 if (refcount->cursor >= refcount->count)
 286                         return 0;
 287                 list = refcount->list;
 288                 if (list[refcount->cursor].ea_count) {
 289                         if (ret)
 290                                 *ret = list[refcount->cursor].ea_count;
 291                         return list[refcount->cursor++].ea_blk;
 292                 }
 293                 refcount->cursor++;
 294         }
 295 }
 296
 297
 298 #ifdef TEST_PROGRAM
 299
 300 errcode_t ea_refcount_validate(ext2_refcount_t refcount, FILE *out)
 301 {
 302         errcode_t       ret = 0;
 303         int             i;
 304         const char *bad = "bad refcount";
 305
 306         if (refcount->count > refcount->size) {
 307                 fprintf(out, "%s: count > size\n", bad);
 308                 return EXT2_ET_INVALID_ARGUMENT;
 309         }
 310         for (i=1; i < refcount->count; i++) {
 311                 if (refcount->list[i-1].ea_blk >= refcount->list[i].ea_blk) {
 312                         fprintf(out,
 313                                 "%s: list[%d].blk=%llu, list[%d].blk=%llu\n",
 314                                 bad, i-1, refcount->list[i-1].ea_blk,
 315                                 i, refcount->list[i].ea_blk);
 316                         ret = EXT2_ET_INVALID_ARGUMENT;
 317                 }
 318         }
 319         return ret;
 320 }
 321
 322 #define BCODE_END       0
 323 #define BCODE_CREATE    1
 324 #define BCODE_FREE      2
 325 #define BCODE_STORE     3
 326 #define BCODE_INCR      4
 327 #define BCODE_DECR      5
 328 #define BCODE_FETCH     6
 329 #define BCODE_VALIDATE  7
 330 #define BCODE_LIST      8
 331 #define BCODE_COLLAPSE 9
 332
 333 int bcode_program[] = {
 334         BCODE_CREATE, 5,
 335         BCODE_STORE, 3, 3,
 336         BCODE_STORE, 4, 4,
 337         BCODE_STORE, 1, 1,
 338         BCODE_STORE, 8, 8,
 339         BCODE_STORE, 2, 2,
 340         BCODE_STORE, 4, 0,
 341         BCODE_STORE, 2, 0,
 342         BCODE_STORE, 6, 6,
 343         BCODE_VALIDATE,
 344         BCODE_STORE, 4, 4,
 345         BCODE_STORE, 2, 2,
 346         BCODE_FETCH, 1,
 347         BCODE_FETCH, 2,
 348         BCODE_INCR, 3,
 349         BCODE_INCR, 3,
 350         BCODE_DECR, 4,
 351         BCODE_STORE, 4, 4,
 352         BCODE_VALIDATE,
 353         BCODE_STORE, 20, 20,
 354         BCODE_STORE, 40, 40,
 355         BCODE_STORE, 30, 30,
 356         BCODE_STORE, 10, 10,
 357         BCODE_DECR, 30,
 358         BCODE_FETCH, 30,
 359         BCODE_DECR, 2,
 360         BCODE_DECR, 2,
 361         BCODE_COLLAPSE,
 362         BCODE_LIST,
 363         BCODE_VALIDATE,
 364         BCODE_FREE,
 365         BCODE_END
 366 };
 367
 368 int main(int argc, char **argv)
 369 {
 370         int     i = 0;
 371         ext2_refcount_t refcount;
 372         int             size, arg;
 373         blk64_t         blk;
 374         errcode_t       retval;
 375
 376         while (1) {
 377                 switch (bcode_program[i++]) {
 378                 case BCODE_END:
 379                         exit(0);
 380                 case BCODE_CREATE:
 381                         size = bcode_program[i++];
 382                         retval = ea_refcount_create(size, &refcount);
 383                         if (retval) {
 384                                 com_err("ea_refcount_create", retval,
 385                                         "while creating size %d", size);
 386                                 exit(1);
 387                         } else
 388                                 printf("Creating refcount with size %d\n",
 389                                        size);
 390                         break;
 391                 case BCODE_FREE:
 392                         ea_refcount_free(refcount);
 393                         refcount = 0;
 394                         printf("Freeing refcount\n");
 395                         break;
 396                 case BCODE_STORE:
 397                         blk = (blk_t) bcode_program[i++];
 398                         arg = bcode_program[i++];
 399                         printf("Storing blk %llu with value %d\n", blk, arg);
 400                         retval = ea_refcount_store(refcount, blk, arg);
 401                         if (retval)
 402                                 com_err("ea_refcount_store", retval,
 403                                         "while storing blk %llu", blk);
 404                         break;
 405                 case BCODE_FETCH:
 406                         blk = (blk_t) bcode_program[i++];
 407                         retval = ea_refcount_fetch(refcount, blk, &arg);
 408                         if (retval)
 409                                 com_err("ea_refcount_fetch", retval,
 410                                         "while fetching blk %llu", blk);
 411                         else
 412                                 printf("bcode_fetch(%llu) returns %d\n",
 413                                        blk, arg);
 414                         break;
 415                 case BCODE_INCR:
 416                         blk = (blk_t) bcode_program[i++];
 417                         retval = ea_refcount_increment(refcount, blk, &arg);
 418                         if (retval)
 419                                 com_err("ea_refcount_increment", retval,
 420                                         "while incrementing blk %llu", blk);
 421                         else
 422                                 printf("bcode_increment(%llu) returns %d\n",
 423                                        blk, arg);
 424                         break;
 425                 case BCODE_DECR:
 426                         blk = (blk_t) bcode_program[i++];
 427                         retval = ea_refcount_decrement(refcount, blk, &arg);
 428                         if (retval)
 429                                 com_err("ea_refcount_decrement", retval,
 430                                         "while decrementing blk %llu", blk);
 431                         else
 432                                 printf("bcode_decrement(%llu) returns %d\n",
 433                                        blk, arg);
 434                         break;
 435                 case BCODE_VALIDATE:
 436                         retval = ea_refcount_validate(refcount, stderr);
 437                         if (retval)
 438                                 com_err("ea_refcount_validate", retval,
 439                                         "while validating");
 440                         else
 441                                 printf("Refcount validation OK.\n");
 442                         break;
 443                 case BCODE_LIST:
 444                         ea_refcount_intr_begin(refcount);
 445                         while (1) {
 446                                 blk = ea_refcount_intr_next(refcount, &arg);
 447                                 if (!blk)
 448                                         break;
 449                                 printf("\tblk=%llu, count=%d\n", blk, arg);
 450                         }
 451                         break;
 452                 case BCODE_COLLAPSE:
 453                         refcount_collapse(refcount);
 454                         break;
 455                 }
 456
 457         }
 458 }
 459
 460 #endif