1 /* 2 * Copyright (C) 2004, OGAWA Hirofumi 3 * Released under GPL v2. 4 */ 5 6 #include <linux/module.h> 7 #include <linux/fs.h> 8 #include <linux/msdos_fs.h> 9 #include <linux/blkdev.h> 10 #include "fat.h" 11 12 struct fatent_operations { 13 void (*ent_blocknr)(struct super_block *, int, int *, sector_t *); 14 void (*ent_set_ptr)(struct fat_entry *, int); 15 int (*ent_bread)(struct super_block *, struct fat_entry *, 16 int, sector_t); 17 int (*ent_get)(struct fat_entry *); 18 void (*ent_put)(struct fat_entry *, int); 19 int (*ent_next)(struct fat_entry *); 20 }; 21 22 static DEFINE_SPINLOCK(fat12_entry_lock); 23 24 static void fat12_ent_blocknr(struct super_block *sb, int entry, 25 int *offset, sector_t *blocknr) 26 { 27 struct msdos_sb_info *sbi = MSDOS_SB(sb); 28 int bytes = entry + (entry >> 1); 29 WARN_ON(entry < FAT_START_ENT || sbi->max_cluster <= entry); 30 *offset = bytes & (sb->s_blocksize - 1); 31 *blocknr = sbi->fat_start + (bytes >> sb->s_blocksize_bits); 32 } 33 34 static void fat_ent_blocknr(struct super_block *sb, int entry, 35 int *offset, sector_t *blocknr) 36 { 37 struct msdos_sb_info *sbi = MSDOS_SB(sb); 38 int bytes = (entry << sbi->fatent_shift); 39 WARN_ON(entry < FAT_START_ENT || sbi->max_cluster <= entry); 40 *offset = bytes & (sb->s_blocksize - 1); 41 *blocknr = sbi->fat_start + (bytes >> sb->s_blocksize_bits); 42 } 43 44 static void fat12_ent_set_ptr(struct fat_entry *fatent, int offset) 45 { 46 struct buffer_head **bhs = fatent->bhs; 47 if (fatent->nr_bhs == 1) { 48 WARN_ON(offset >= (bhs[0]->b_size - 1)); 49 fatent->u.ent12_p[0] = bhs[0]->b_data + offset; 50 fatent->u.ent12_p[1] = bhs[0]->b_data + (offset + 1); 51 } else { 52 WARN_ON(offset != (bhs[0]->b_size - 1)); 53 fatent->u.ent12_p[0] = bhs[0]->b_data + offset; 54 fatent->u.ent12_p[1] = bhs[1]->b_data; 55 } 56 } 57 58 static void fat16_ent_set_ptr(struct fat_entry *fatent, int offset) 59 { 60 WARN_ON(offset & (2 - 1)); 61 fatent->u.ent16_p = (__le16 *)(fatent->bhs[0]->b_data + offset); 62 } 63 64 static void fat32_ent_set_ptr(struct fat_entry *fatent, int offset) 65 { 66 WARN_ON(offset & (4 - 1)); 67 fatent->u.ent32_p = (__le32 *)(fatent->bhs[0]->b_data + offset); 68 } 69 70 static int fat12_ent_bread(struct super_block *sb, struct fat_entry *fatent, 71 int offset, sector_t blocknr) 72 { 73 struct buffer_head **bhs = fatent->bhs; 74 75 WARN_ON(blocknr < MSDOS_SB(sb)->fat_start); 76 fatent->fat_inode = MSDOS_SB(sb)->fat_inode; 77 78 bhs[0] = sb_bread(sb, blocknr); 79 if (!bhs[0]) 80 goto err; 81 82 if ((offset + 1) < sb->s_blocksize) 83 fatent->nr_bhs = 1; 84 else { 85 /* This entry is block boundary, it needs the next block */ 86 blocknr++; 87 bhs[1] = sb_bread(sb, blocknr); 88 if (!bhs[1]) 89 goto err_brelse; 90 fatent->nr_bhs = 2; 91 } 92 fat12_ent_set_ptr(fatent, offset); 93 return 0; 94 95 err_brelse: 96 brelse(bhs[0]); 97 err: 98 printk(KERN_ERR "FAT: FAT read failed (blocknr %llu)\n", (llu)blocknr); 99 return -EIO; 100 } 101 102 static int fat_ent_bread(struct super_block *sb, struct fat_entry *fatent, 103 int offset, sector_t blocknr) 104 { 105 struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops; 106 107 WARN_ON(blocknr < MSDOS_SB(sb)->fat_start); 108 fatent->fat_inode = MSDOS_SB(sb)->fat_inode; 109 fatent->bhs[0] = sb_bread(sb, blocknr); 110 if (!fatent->bhs[0]) { 111 printk(KERN_ERR "FAT: FAT read failed (blocknr %llu)\n", 112 (llu)blocknr); 113 return -EIO; 114 } 115 fatent->nr_bhs = 1; 116 ops->ent_set_ptr(fatent, offset); 117 return 0; 118 } 119 120 static int fat12_ent_get(struct fat_entry *fatent) 121 { 122 u8 **ent12_p = fatent->u.ent12_p; 123 int next; 124 125 spin_lock(&fat12_entry_lock); 126 if (fatent->entry & 1) 127 next = (*ent12_p[0] >> 4) | (*ent12_p[1] << 4); 128 else 129 next = (*ent12_p[1] << 8) | *ent12_p[0]; 130 spin_unlock(&fat12_entry_lock); 131 132 next &= 0x0fff; 133 if (next >= BAD_FAT12) 134 next = FAT_ENT_EOF; 135 return next; 136 } 137 138 static int fat16_ent_get(struct fat_entry *fatent) 139 { 140 int next = le16_to_cpu(*fatent->u.ent16_p); 141 WARN_ON((unsigned long)fatent->u.ent16_p & (2 - 1)); 142 if (next >= BAD_FAT16) 143 next = FAT_ENT_EOF; 144 return next; 145 } 146 147 static int fat32_ent_get(struct fat_entry *fatent) 148 { 149 int next = le32_to_cpu(*fatent->u.ent32_p) & 0x0fffffff; 150 WARN_ON((unsigned long)fatent->u.ent32_p & (4 - 1)); 151 if (next >= BAD_FAT32) 152 next = FAT_ENT_EOF; 153 return next; 154 } 155 156 static void fat12_ent_put(struct fat_entry *fatent, int new) 157 { 158 u8 **ent12_p = fatent->u.ent12_p; 159 160 if (new == FAT_ENT_EOF) 161 new = EOF_FAT12; 162 163 spin_lock(&fat12_entry_lock); 164 if (fatent->entry & 1) { 165 *ent12_p[0] = (new << 4) | (*ent12_p[0] & 0x0f); 166 *ent12_p[1] = new >> 4; 167 } else { 168 *ent12_p[0] = new & 0xff; 169 *ent12_p[1] = (*ent12_p[1] & 0xf0) | (new >> 8); 170 } 171 spin_unlock(&fat12_entry_lock); 172 173 mark_buffer_dirty_inode(fatent->bhs[0], fatent->fat_inode); 174 if (fatent->nr_bhs == 2) 175 mark_buffer_dirty_inode(fatent->bhs[1], fatent->fat_inode); 176 } 177 178 static void fat16_ent_put(struct fat_entry *fatent, int new) 179 { 180 if (new == FAT_ENT_EOF) 181 new = EOF_FAT16; 182 183 *fatent->u.ent16_p = cpu_to_le16(new); 184 mark_buffer_dirty_inode(fatent->bhs[0], fatent->fat_inode); 185 } 186 187 static void fat32_ent_put(struct fat_entry *fatent, int new) 188 { 189 if (new == FAT_ENT_EOF) 190 new = EOF_FAT32; 191 192 WARN_ON(new & 0xf0000000); 193 new |= le32_to_cpu(*fatent->u.ent32_p) & ~0x0fffffff; 194 *fatent->u.ent32_p = cpu_to_le32(new); 195 mark_buffer_dirty_inode(fatent->bhs[0], fatent->fat_inode); 196 } 197 198 static int fat12_ent_next(struct fat_entry *fatent) 199 { 200 u8 **ent12_p = fatent->u.ent12_p; 201 struct buffer_head **bhs = fatent->bhs; 202 u8 *nextp = ent12_p[1] + 1 + (fatent->entry & 1); 203 204 fatent->entry++; 205 if (fatent->nr_bhs == 1) { 206 WARN_ON(ent12_p[0] > (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 2))); 207 WARN_ON(ent12_p[1] > (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 1))); 208 if (nextp < (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 1))) { 209 ent12_p[0] = nextp - 1; 210 ent12_p[1] = nextp; 211 return 1; 212 } 213 } else { 214 WARN_ON(ent12_p[0] != (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 1))); 215 WARN_ON(ent12_p[1] != (u8 *)bhs[1]->b_data); 216 ent12_p[0] = nextp - 1; 217 ent12_p[1] = nextp; 218 brelse(bhs[0]); 219 bhs[0] = bhs[1]; 220 fatent->nr_bhs = 1; 221 return 1; 222 } 223 ent12_p[0] = NULL; 224 ent12_p[1] = NULL; 225 return 0; 226 } 227 228 static int fat16_ent_next(struct fat_entry *fatent) 229 { 230 const struct buffer_head *bh = fatent->bhs[0]; 231 fatent->entry++; 232 if (fatent->u.ent16_p < (__le16 *)(bh->b_data + (bh->b_size - 2))) { 233 fatent->u.ent16_p++; 234 return 1; 235 } 236 fatent->u.ent16_p = NULL; 237 return 0; 238 } 239 240 static int fat32_ent_next(struct fat_entry *fatent) 241 { 242 const struct buffer_head *bh = fatent->bhs[0]; 243 fatent->entry++; 244 if (fatent->u.ent32_p < (__le32 *)(bh->b_data + (bh->b_size - 4))) { 245 fatent->u.ent32_p++; 246 return 1; 247 } 248 fatent->u.ent32_p = NULL; 249 return 0; 250 } 251 252 static struct fatent_operations fat12_ops = { 253 .ent_blocknr = fat12_ent_blocknr, 254 .ent_set_ptr = fat12_ent_set_ptr, 255 .ent_bread = fat12_ent_bread, 256 .ent_get = fat12_ent_get, 257 .ent_put = fat12_ent_put, 258 .ent_next = fat12_ent_next, 259 }; 260 261 static struct fatent_operations fat16_ops = { 262 .ent_blocknr = fat_ent_blocknr, 263 .ent_set_ptr = fat16_ent_set_ptr, 264 .ent_bread = fat_ent_bread, 265 .ent_get = fat16_ent_get, 266 .ent_put = fat16_ent_put, 267 .ent_next = fat16_ent_next, 268 }; 269 270 static struct fatent_operations fat32_ops = { 271 .ent_blocknr = fat_ent_blocknr, 272 .ent_set_ptr = fat32_ent_set_ptr, 273 .ent_bread = fat_ent_bread, 274 .ent_get = fat32_ent_get, 275 .ent_put = fat32_ent_put, 276 .ent_next = fat32_ent_next, 277 }; 278 279 static inline void lock_fat(struct msdos_sb_info *sbi) 280 { 281 mutex_lock(&sbi->fat_lock); 282 } 283 284 static inline void unlock_fat(struct msdos_sb_info *sbi) 285 { 286 mutex_unlock(&sbi->fat_lock); 287 } 288 289 void fat_ent_access_init(struct super_block *sb) 290 { 291 struct msdos_sb_info *sbi = MSDOS_SB(sb); 292 293 mutex_init(&sbi->fat_lock); 294 295 switch (sbi->fat_bits) { 296 case 32: 297 sbi->fatent_shift = 2; 298 sbi->fatent_ops = &fat32_ops; 299 break; 300 case 16: 301 sbi->fatent_shift = 1; 302 sbi->fatent_ops = &fat16_ops; 303 break; 304 case 12: 305 sbi->fatent_shift = -1; 306 sbi->fatent_ops = &fat12_ops; 307 break; 308 } 309 } 310 311 static inline int fat_ent_update_ptr(struct super_block *sb, 312 struct fat_entry *fatent, 313 int offset, sector_t blocknr) 314 { 315 struct msdos_sb_info *sbi = MSDOS_SB(sb); 316 struct fatent_operations *ops = sbi->fatent_ops; 317 struct buffer_head **bhs = fatent->bhs; 318 319 /* Is this fatent's blocks including this entry? */ 320 if (!fatent->nr_bhs || bhs[0]->b_blocknr != blocknr) 321 return 0; 322 if (sbi->fat_bits == 12) { 323 if ((offset + 1) < sb->s_blocksize) { 324 /* This entry is on bhs[0]. */ 325 if (fatent->nr_bhs == 2) { 326 brelse(bhs[1]); 327 fatent->nr_bhs = 1; 328 } 329 } else { 330 /* This entry needs the next block. */ 331 if (fatent->nr_bhs != 2) 332 return 0; 333 if (bhs[1]->b_blocknr != (blocknr + 1)) 334 return 0; 335 } 336 } 337 ops->ent_set_ptr(fatent, offset); 338 return 1; 339 } 340 341 int fat_ent_read(struct inode *inode, struct fat_entry *fatent, int entry) 342 { 343 struct super_block *sb = inode->i_sb; 344 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb); 345 struct fatent_operations *ops = sbi->fatent_ops; 346 int err, offset; 347 sector_t blocknr; 348 349 if (entry < FAT_START_ENT || sbi->max_cluster <= entry) { 350 fatent_brelse(fatent); 351 fat_fs_error(sb, "invalid access to FAT (entry 0x%08x)", entry); 352 return -EIO; 353 } 354 355 fatent_set_entry(fatent, entry); 356 ops->ent_blocknr(sb, entry, &offset, &blocknr); 357 358 if (!fat_ent_update_ptr(sb, fatent, offset, blocknr)) { 359 fatent_brelse(fatent); 360 err = ops->ent_bread(sb, fatent, offset, blocknr); 361 if (err) 362 return err; 363 } 364 return ops->ent_get(fatent); 365 } 366 367 /* FIXME: We can write the blocks as more big chunk. */ 368 static int fat_mirror_bhs(struct super_block *sb, struct buffer_head **bhs, 369 int nr_bhs) 370 { 371 struct msdos_sb_info *sbi = MSDOS_SB(sb); 372 struct buffer_head *c_bh; 373 int err, n, copy; 374 375 err = 0; 376 for (copy = 1; copy < sbi->fats; copy++) { 377 sector_t backup_fat = sbi->fat_length * copy; 378 379 for (n = 0; n < nr_bhs; n++) { 380 c_bh = sb_getblk(sb, backup_fat + bhs[n]->b_blocknr); 381 if (!c_bh) { 382 err = -ENOMEM; 383 goto error; 384 } 385 memcpy(c_bh->b_data, bhs[n]->b_data, sb->s_blocksize); 386 set_buffer_uptodate(c_bh); 387 mark_buffer_dirty_inode(c_bh, sbi->fat_inode); 388 if (sb->s_flags & MS_SYNCHRONOUS) 389 err = sync_dirty_buffer(c_bh); 390 brelse(c_bh); 391 if (err) 392 goto error; 393 } 394 } 395 error: 396 return err; 397 } 398 399 int fat_ent_write(struct inode *inode, struct fat_entry *fatent, 400 int new, int wait) 401 { 402 struct super_block *sb = inode->i_sb; 403 struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops; 404 int err; 405 406 ops->ent_put(fatent, new); 407 if (wait) { 408 err = fat_sync_bhs(fatent->bhs, fatent->nr_bhs); 409 if (err) 410 return err; 411 } 412 return fat_mirror_bhs(sb, fatent->bhs, fatent->nr_bhs); 413 } 414 415 static inline int fat_ent_next(struct msdos_sb_info *sbi, 416 struct fat_entry *fatent) 417 { 418 if (sbi->fatent_ops->ent_next(fatent)) { 419 if (fatent->entry < sbi->max_cluster) 420 return 1; 421 } 422 return 0; 423 } 424 425 static inline int fat_ent_read_block(struct super_block *sb, 426 struct fat_entry *fatent) 427 { 428 struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops; 429 sector_t blocknr; 430 int offset; 431 432 fatent_brelse(fatent); 433 ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr); 434 return ops->ent_bread(sb, fatent, offset, blocknr); 435 } 436 437 static void fat_collect_bhs(struct buffer_head **bhs, int *nr_bhs, 438 struct fat_entry *fatent) 439 { 440 int n, i; 441 442 for (n = 0; n < fatent->nr_bhs; n++) { 443 for (i = 0; i < *nr_bhs; i++) { 444 if (fatent->bhs[n] == bhs[i]) 445 break; 446 } 447 if (i == *nr_bhs) { 448 get_bh(fatent->bhs[n]); 449 bhs[i] = fatent->bhs[n]; 450 (*nr_bhs)++; 451 } 452 } 453 } 454 455 int fat_alloc_clusters(struct inode *inode, int *cluster, int nr_cluster) 456 { 457 struct super_block *sb = inode->i_sb; 458 struct msdos_sb_info *sbi = MSDOS_SB(sb); 459 struct fatent_operations *ops = sbi->fatent_ops; 460 struct fat_entry fatent, prev_ent; 461 struct buffer_head *bhs[MAX_BUF_PER_PAGE]; 462 int i, count, err, nr_bhs, idx_clus; 463 464 BUG_ON(nr_cluster > (MAX_BUF_PER_PAGE / 2)); /* fixed limit */ 465 466 lock_fat(sbi); 467 if (sbi->free_clusters != -1 && sbi->free_clus_valid && 468 sbi->free_clusters < nr_cluster) { 469 unlock_fat(sbi); 470 return -ENOSPC; 471 } 472 473 err = nr_bhs = idx_clus = 0; 474 count = FAT_START_ENT; 475 fatent_init(&prev_ent); 476 fatent_init(&fatent); 477 fatent_set_entry(&fatent, sbi->prev_free + 1); 478 while (count < sbi->max_cluster) { 479 if (fatent.entry >= sbi->max_cluster) 480 fatent.entry = FAT_START_ENT; 481 fatent_set_entry(&fatent, fatent.entry); 482 err = fat_ent_read_block(sb, &fatent); 483 if (err) 484 goto out; 485 486 /* Find the free entries in a block */ 487 do { 488 if (ops->ent_get(&fatent) == FAT_ENT_FREE) { 489 int entry = fatent.entry; 490 491 /* make the cluster chain */ 492 ops->ent_put(&fatent, FAT_ENT_EOF); 493 if (prev_ent.nr_bhs) 494 ops->ent_put(&prev_ent, entry); 495 496 fat_collect_bhs(bhs, &nr_bhs, &fatent); 497 498 sbi->prev_free = entry; 499 if (sbi->free_clusters != -1) 500 sbi->free_clusters--; 501 sb->s_dirt = 1; 502 503 cluster[idx_clus] = entry; 504 idx_clus++; 505 if (idx_clus == nr_cluster) 506 goto out; 507 508 /* 509 * fat_collect_bhs() gets ref-count of bhs, 510 * so we can still use the prev_ent. 511 */ 512 prev_ent = fatent; 513 } 514 count++; 515 if (count == sbi->max_cluster) 516 break; 517 } while (fat_ent_next(sbi, &fatent)); 518 } 519 520 /* Couldn't allocate the free entries */ 521 sbi->free_clusters = 0; 522 sbi->free_clus_valid = 1; 523 sb->s_dirt = 1; 524 err = -ENOSPC; 525 526 out: 527 unlock_fat(sbi); 528 fatent_brelse(&fatent); 529 if (!err) { 530 if (inode_needs_sync(inode)) 531 err = fat_sync_bhs(bhs, nr_bhs); 532 if (!err) 533 err = fat_mirror_bhs(sb, bhs, nr_bhs); 534 } 535 for (i = 0; i < nr_bhs; i++) 536 brelse(bhs[i]); 537 538 if (err && idx_clus) 539 fat_free_clusters(inode, cluster[0]); 540 541 return err; 542 } 543 544 int fat_free_clusters(struct inode *inode, int cluster) 545 { 546 struct super_block *sb = inode->i_sb; 547 struct msdos_sb_info *sbi = MSDOS_SB(sb); 548 struct fatent_operations *ops = sbi->fatent_ops; 549 struct fat_entry fatent; 550 struct buffer_head *bhs[MAX_BUF_PER_PAGE]; 551 int i, err, nr_bhs; 552 int first_cl = cluster; 553 554 nr_bhs = 0; 555 fatent_init(&fatent); 556 lock_fat(sbi); 557 do { 558 cluster = fat_ent_read(inode, &fatent, cluster); 559 if (cluster < 0) { 560 err = cluster; 561 goto error; 562 } else if (cluster == FAT_ENT_FREE) { 563 fat_fs_error(sb, "%s: deleting FAT entry beyond EOF", 564 __func__); 565 err = -EIO; 566 goto error; 567 } 568 569 if (sbi->options.discard) { 570 /* 571 * Issue discard for the sectors we no longer 572 * care about, batching contiguous clusters 573 * into one request 574 */ 575 if (cluster != fatent.entry + 1) { 576 int nr_clus = fatent.entry - first_cl + 1; 577 578 sb_issue_discard(sb, 579 fat_clus_to_blknr(sbi, first_cl), 580 nr_clus * sbi->sec_per_clus); 581 582 first_cl = cluster; 583 } 584 } 585 586 ops->ent_put(&fatent, FAT_ENT_FREE); 587 if (sbi->free_clusters != -1) { 588 sbi->free_clusters++; 589 sb->s_dirt = 1; 590 } 591 592 if (nr_bhs + fatent.nr_bhs > MAX_BUF_PER_PAGE) { 593 if (sb->s_flags & MS_SYNCHRONOUS) { 594 err = fat_sync_bhs(bhs, nr_bhs); 595 if (err) 596 goto error; 597 } 598 err = fat_mirror_bhs(sb, bhs, nr_bhs); 599 if (err) 600 goto error; 601 for (i = 0; i < nr_bhs; i++) 602 brelse(bhs[i]); 603 nr_bhs = 0; 604 } 605 fat_collect_bhs(bhs, &nr_bhs, &fatent); 606 } while (cluster != FAT_ENT_EOF); 607 608 if (sb->s_flags & MS_SYNCHRONOUS) { 609 err = fat_sync_bhs(bhs, nr_bhs); 610 if (err) 611 goto error; 612 } 613 err = fat_mirror_bhs(sb, bhs, nr_bhs); 614 error: 615 fatent_brelse(&fatent); 616 for (i = 0; i < nr_bhs; i++) 617 brelse(bhs[i]); 618 unlock_fat(sbi); 619 620 return err; 621 } 622 623 EXPORT_SYMBOL_GPL(fat_free_clusters); 624 625 /* 128kb is the whole sectors for FAT12 and FAT16 */ 626 #define FAT_READA_SIZE (128 * 1024) 627 628 static void fat_ent_reada(struct super_block *sb, struct fat_entry *fatent, 629 unsigned long reada_blocks) 630 { 631 struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops; 632 sector_t blocknr; 633 int i, offset; 634 635 ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr); 636 637 for (i = 0; i < reada_blocks; i++) 638 sb_breadahead(sb, blocknr + i); 639 } 640 641 int fat_count_free_clusters(struct super_block *sb) 642 { 643 struct msdos_sb_info *sbi = MSDOS_SB(sb); 644 struct fatent_operations *ops = sbi->fatent_ops; 645 struct fat_entry fatent; 646 unsigned long reada_blocks, reada_mask, cur_block; 647 int err = 0, free; 648 649 lock_fat(sbi); 650 if (sbi->free_clusters != -1 && sbi->free_clus_valid) 651 goto out; 652 653 reada_blocks = FAT_READA_SIZE >> sb->s_blocksize_bits; 654 reada_mask = reada_blocks - 1; 655 cur_block = 0; 656 657 free = 0; 658 fatent_init(&fatent); 659 fatent_set_entry(&fatent, FAT_START_ENT); 660 while (fatent.entry < sbi->max_cluster) { 661 /* readahead of fat blocks */ 662 if ((cur_block & reada_mask) == 0) { 663 unsigned long rest = sbi->fat_length - cur_block; 664 fat_ent_reada(sb, &fatent, min(reada_blocks, rest)); 665 } 666 cur_block++; 667 668 err = fat_ent_read_block(sb, &fatent); 669 if (err) 670 goto out; 671 672 do { 673 if (ops->ent_get(&fatent) == FAT_ENT_FREE) 674 free++; 675 } while (fat_ent_next(sbi, &fatent)); 676 } 677 sbi->free_clusters = free; 678 sbi->free_clus_valid = 1; 679 sb->s_dirt = 1; 680 fatent_brelse(&fatent); 681 out: 682 unlock_fat(sbi); 683 return err; 684 } 685