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         blk64_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                                                  blk64_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                                               blk64_t blk, int create)
 157 {
 158         int     low, high, mid;
 159
 160         if (!refcount || !refcount->list)
 161                 return 0;
 162 retry:
 163         low = 0;
 164         high = (int) refcount->count-1;
 165         if (create && ((refcount->count == 0) ||
 166                        (blk > refcount->list[high].ea_blk))) {
 167                 if (refcount->count >= refcount->size)
 168                         refcount_collapse(refcount);
 169
 170                 return insert_refcount_el(refcount, blk,
 171                                           (unsigned) refcount->count);
 172         }
 173         if (refcount->count == 0)
 174                 return 0;
 175
 176         if (refcount->cursor >= refcount->count)
 177                 refcount->cursor = 0;
 178         if (blk == refcount->list[refcount->cursor].ea_blk)
 179                 return &refcount->list[refcount->cursor++];
 180 #ifdef DEBUG
 181         printf("Non-cursor get_refcount_el: %u\n", blk);
 182 #endif
 183         while (low <= high) {
 184                 mid = (low+high)/2;
 185                 if (blk == refcount->list[mid].ea_blk) {
 186                         refcount->cursor = mid+1;
 187                         return &refcount->list[mid];
 188                 }
 189                 if (blk < refcount->list[mid].ea_blk)
 190                         high = mid-1;
 191                 else
 192                         low = mid+1;
 193         }
 194         /*
 195          * If we need to create a new entry, it should be right at
 196          * low (where high will be left at low-1).
 197          */
 198         if (create) {
 199                 if (refcount->count >= refcount->size) {
 200                         refcount_collapse(refcount);
 201                         if (refcount->count < refcount->size)
 202                                 goto retry;
 203                 }
 204                 return insert_refcount_el(refcount, blk, low);
 205         }
 206         return 0;
 207 }
 208
 209 errcode_t ea_refcount_fetch(ext2_refcount_t refcount, blk64_t blk,
 210                                 int *ret)
 211 {
 212         struct ea_refcount_el   *el;
 213
 214         el = get_refcount_el(refcount, blk, 0);
 215         if (!el) {
 216                 *ret = 0;
 217                 return 0;
 218         }
 219         *ret = el->ea_count;
 220         return 0;
 221 }
 222
 223 errcode_t ea_refcount_increment(ext2_refcount_t refcount, blk64_t blk, int *ret)
 224 {
 225         struct ea_refcount_el   *el;
 226
 227         el = get_refcount_el(refcount, blk, 1);
 228         if (!el)
 229                 return EXT2_ET_NO_MEMORY;
 230         el->ea_count++;
 231
 232         if (ret)
 233                 *ret = el->ea_count;
 234         return 0;
 235 }
 236
 237 errcode_t ea_refcount_decrement(ext2_refcount_t refcount, blk64_t blk, int *ret)
 238 {
 239         struct ea_refcount_el   *el;
 240
 241         el = get_refcount_el(refcount, blk, 0);
 242         if (!el || el->ea_count == 0)
 243                 return EXT2_ET_INVALID_ARGUMENT;
 244
 245         el->ea_count--;
 246
 247         if (ret)
 248                 *ret = el->ea_count;
 249         return 0;
 250 }
 251
 252 errcode_t ea_refcount_store(ext2_refcount_t refcount, blk64_t blk, int count)
 253 {
 254         struct ea_refcount_el   *el;
 255
 256         /*
 257          * Get the refcount element
 258          */
 259         el = get_refcount_el(refcount, blk, count ? 1 : 0);
 260         if (!el)
 261                 return count ? EXT2_ET_NO_MEMORY : 0;
 262         el->ea_count = count;
 263         return 0;
 264 }
 265
 266 blk_t ext2fs_get_refcount_size(ext2_refcount_t refcount)
 267 {
 268         if (!refcount)
 269                 return 0;
 270
 271         return refcount->size;
 272 }
 273
 274 void ea_refcount_intr_begin(ext2_refcount_t refcount)
 275 {
 276         refcount->cursor = 0;
 277 }
 278
 279
 280 blk64_t ea_refcount_intr_next(ext2_refcount_t refcount,
 281                                 int *ret)
 282 {
 283         struct ea_refcount_el   *list;
 284
 285         while (1) {
 286                 if (refcount->cursor >= refcount->count)
 287                         return 0;
 288                 list = refcount->list;
 289                 if (list[refcount->cursor].ea_count) {
 290                         if (ret)
 291                                 *ret = list[refcount->cursor].ea_count;
 292                         return list[refcount->cursor++].ea_blk;
 293                 }
 294                 refcount->cursor++;
 295         }
 296 }
 297
 298
 299 #ifdef TEST_PROGRAM
 300
 301 errcode_t ea_refcount_validate(ext2_refcount_t refcount, FILE *out)
 302 {
 303         errcode_t       ret = 0;
 304         int             i;
 305         const char *bad = "bad refcount";
 306
 307         if (refcount->count > refcount->size) {
 308                 fprintf(out, "%s: count > size\n", bad);
 309                 return EXT2_ET_INVALID_ARGUMENT;
 310         }
 311         for (i=1; i < refcount->count; i++) {
 312                 if (refcount->list[i-1].ea_blk >= refcount->list[i].ea_blk) {
 313                         fprintf(out, "%s: list[%d].blk=%u, list[%d].blk=%u\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 %u 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 %u", 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 %u", blk);
 411                         else
 412                                 printf("bcode_fetch(%u) 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 %u", blk);
 421                         else
 422                                 printf("bcode_increment(%u) 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 %u", blk);
 431                         else
 432                                 printf("bcode_decrement(%u) 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=%u, 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