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 fat_msg(sb, KERN_ERR, "FAT read failed (blocknr %llu)", (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 fat_msg(sb, KERN_ERR, "FAT read failed (blocknr %llu)", 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 WARN_ON(new & 0xf0000000); 190 new |= le32_to_cpu(*fatent->u.ent32_p) & ~0x0fffffff; 191 *fatent->u.ent32_p = cpu_to_le32(new); 192 mark_buffer_dirty_inode(fatent->bhs[0], fatent->fat_inode); 193 } 194 195 static int fat12_ent_next(struct fat_entry *fatent) 196 { 197 u8 **ent12_p = fatent->u.ent12_p; 198 struct buffer_head **bhs = fatent->bhs; 199 u8 *nextp = ent12_p[1] + 1 + (fatent->entry & 1); 200 201 fatent->entry++; 202 if (fatent->nr_bhs == 1) { 203 WARN_ON(ent12_p[0] > (u8 *)(bhs[0]->b_data + 204 (bhs[0]->b_size - 2))); 205 WARN_ON(ent12_p[1] > (u8 *)(bhs[0]->b_data + 206 (bhs[0]->b_size - 1))); 207 if (nextp < (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 1))) { 208 ent12_p[0] = nextp - 1; 209 ent12_p[1] = nextp; 210 return 1; 211 } 212 } else { 213 WARN_ON(ent12_p[0] != (u8 *)(bhs[0]->b_data + 214 (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 void mark_fsinfo_dirty(struct super_block *sb) 312 { 313 struct msdos_sb_info *sbi = MSDOS_SB(sb); 314 315 if (sb->s_flags & MS_RDONLY || sbi->fat_bits != 32) 316 return; 317 318 __mark_inode_dirty(sbi->fsinfo_inode, I_DIRTY_SYNC); 319 } 320 321 static inline int fat_ent_update_ptr(struct super_block *sb, 322 struct fat_entry *fatent, 323 int offset, sector_t blocknr) 324 { 325 struct msdos_sb_info *sbi = MSDOS_SB(sb); 326 struct fatent_operations *ops = sbi->fatent_ops; 327 struct buffer_head **bhs = fatent->bhs; 328 329 /* Is this fatent's blocks including this entry? */ 330 if (!fatent->nr_bhs || bhs[0]->b_blocknr != blocknr) 331 return 0; 332 if (sbi->fat_bits == 12) { 333 if ((offset + 1) < sb->s_blocksize) { 334 /* This entry is on bhs[0]. */ 335 if (fatent->nr_bhs == 2) { 336 brelse(bhs[1]); 337 fatent->nr_bhs = 1; 338 } 339 } else { 340 /* This entry needs the next block. */ 341 if (fatent->nr_bhs != 2) 342 return 0; 343 if (bhs[1]->b_blocknr != (blocknr + 1)) 344 return 0; 345 } 346 } 347 ops->ent_set_ptr(fatent, offset); 348 return 1; 349 } 350 351 int fat_ent_read(struct inode *inode, struct fat_entry *fatent, int entry) 352 { 353 struct super_block *sb = inode->i_sb; 354 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb); 355 struct fatent_operations *ops = sbi->fatent_ops; 356 int err, offset; 357 sector_t blocknr; 358 359 if (entry < FAT_START_ENT || sbi->max_cluster <= entry) { 360 fatent_brelse(fatent); 361 fat_fs_error(sb, "invalid access to FAT (entry 0x%08x)", entry); 362 return -EIO; 363 } 364 365 fatent_set_entry(fatent, entry); 366 ops->ent_blocknr(sb, entry, &offset, &blocknr); 367 368 if (!fat_ent_update_ptr(sb, fatent, offset, blocknr)) { 369 fatent_brelse(fatent); 370 err = ops->ent_bread(sb, fatent, offset, blocknr); 371 if (err) 372 return err; 373 } 374 return ops->ent_get(fatent); 375 } 376 377 /* FIXME: We can write the blocks as more big chunk. */ 378 static int fat_mirror_bhs(struct super_block *sb, struct buffer_head **bhs, 379 int nr_bhs) 380 { 381 struct msdos_sb_info *sbi = MSDOS_SB(sb); 382 struct buffer_head *c_bh; 383 int err, n, copy; 384 385 err = 0; 386 for (copy = 1; copy < sbi->fats; copy++) { 387 sector_t backup_fat = sbi->fat_length * copy; 388 389 for (n = 0; n < nr_bhs; n++) { 390 c_bh = sb_getblk(sb, backup_fat + bhs[n]->b_blocknr); 391 if (!c_bh) { 392 err = -ENOMEM; 393 goto error; 394 } 395 memcpy(c_bh->b_data, bhs[n]->b_data, sb->s_blocksize); 396 set_buffer_uptodate(c_bh); 397 mark_buffer_dirty_inode(c_bh, sbi->fat_inode); 398 if (sb->s_flags & MS_SYNCHRONOUS) 399 err = sync_dirty_buffer(c_bh); 400 brelse(c_bh); 401 if (err) 402 goto error; 403 } 404 } 405 error: 406 return err; 407 } 408 409 int fat_ent_write(struct inode *inode, struct fat_entry *fatent, 410 int new, int wait) 411 { 412 struct super_block *sb = inode->i_sb; 413 struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops; 414 int err; 415 416 ops->ent_put(fatent, new); 417 if (wait) { 418 err = fat_sync_bhs(fatent->bhs, fatent->nr_bhs); 419 if (err) 420 return err; 421 } 422 return fat_mirror_bhs(sb, fatent->bhs, fatent->nr_bhs); 423 } 424 425 static inline int fat_ent_next(struct msdos_sb_info *sbi, 426 struct fat_entry *fatent) 427 { 428 if (sbi->fatent_ops->ent_next(fatent)) { 429 if (fatent->entry < sbi->max_cluster) 430 return 1; 431 } 432 return 0; 433 } 434 435 static inline int fat_ent_read_block(struct super_block *sb, 436 struct fat_entry *fatent) 437 { 438 struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops; 439 sector_t blocknr; 440 int offset; 441 442 fatent_brelse(fatent); 443 ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr); 444 return ops->ent_bread(sb, fatent, offset, blocknr); 445 } 446 447 static void fat_collect_bhs(struct buffer_head **bhs, int *nr_bhs, 448 struct fat_entry *fatent) 449 { 450 int n, i; 451 452 for (n = 0; n < fatent->nr_bhs; n++) { 453 for (i = 0; i < *nr_bhs; i++) { 454 if (fatent->bhs[n] == bhs[i]) 455 break; 456 } 457 if (i == *nr_bhs) { 458 get_bh(fatent->bhs[n]); 459 bhs[i] = fatent->bhs[n]; 460 (*nr_bhs)++; 461 } 462 } 463 } 464 465 int fat_alloc_clusters(struct inode *inode, int *cluster, int nr_cluster) 466 { 467 struct super_block *sb = inode->i_sb; 468 struct msdos_sb_info *sbi = MSDOS_SB(sb); 469 struct fatent_operations *ops = sbi->fatent_ops; 470 struct fat_entry fatent, prev_ent; 471 struct buffer_head *bhs[MAX_BUF_PER_PAGE]; 472 int i, count, err, nr_bhs, idx_clus; 473 474 BUG_ON(nr_cluster > (MAX_BUF_PER_PAGE / 2)); /* fixed limit */ 475 476 lock_fat(sbi); 477 if (sbi->free_clusters != -1 && sbi->free_clus_valid && 478 sbi->free_clusters < nr_cluster) { 479 unlock_fat(sbi); 480 return -ENOSPC; 481 } 482 483 err = nr_bhs = idx_clus = 0; 484 count = FAT_START_ENT; 485 fatent_init(&prev_ent); 486 fatent_init(&fatent); 487 fatent_set_entry(&fatent, sbi->prev_free + 1); 488 while (count < sbi->max_cluster) { 489 if (fatent.entry >= sbi->max_cluster) 490 fatent.entry = FAT_START_ENT; 491 fatent_set_entry(&fatent, fatent.entry); 492 err = fat_ent_read_block(sb, &fatent); 493 if (err) 494 goto out; 495 496 /* Find the free entries in a block */ 497 do { 498 if (ops->ent_get(&fatent) == FAT_ENT_FREE) { 499 int entry = fatent.entry; 500 501 /* make the cluster chain */ 502 ops->ent_put(&fatent, FAT_ENT_EOF); 503 if (prev_ent.nr_bhs) 504 ops->ent_put(&prev_ent, entry); 505 506 fat_collect_bhs(bhs, &nr_bhs, &fatent); 507 508 sbi->prev_free = entry; 509 if (sbi->free_clusters != -1) 510 sbi->free_clusters--; 511 512 cluster[idx_clus] = entry; 513 idx_clus++; 514 if (idx_clus == nr_cluster) 515 goto out; 516 517 /* 518 * fat_collect_bhs() gets ref-count of bhs, 519 * so we can still use the prev_ent. 520 */ 521 prev_ent = fatent; 522 } 523 count++; 524 if (count == sbi->max_cluster) 525 break; 526 } while (fat_ent_next(sbi, &fatent)); 527 } 528 529 /* Couldn't allocate the free entries */ 530 sbi->free_clusters = 0; 531 sbi->free_clus_valid = 1; 532 err = -ENOSPC; 533 534 out: 535 unlock_fat(sbi); 536 mark_fsinfo_dirty(sb); 537 fatent_brelse(&fatent); 538 if (!err) { 539 if (inode_needs_sync(inode)) 540 err = fat_sync_bhs(bhs, nr_bhs); 541 if (!err) 542 err = fat_mirror_bhs(sb, bhs, nr_bhs); 543 } 544 for (i = 0; i < nr_bhs; i++) 545 brelse(bhs[i]); 546 547 if (err && idx_clus) 548 fat_free_clusters(inode, cluster[0]); 549 550 return err; 551 } 552 553 int fat_free_clusters(struct inode *inode, int cluster) 554 { 555 struct super_block *sb = inode->i_sb; 556 struct msdos_sb_info *sbi = MSDOS_SB(sb); 557 struct fatent_operations *ops = sbi->fatent_ops; 558 struct fat_entry fatent; 559 struct buffer_head *bhs[MAX_BUF_PER_PAGE]; 560 int i, err, nr_bhs; 561 int first_cl = cluster, dirty_fsinfo = 0; 562 563 nr_bhs = 0; 564 fatent_init(&fatent); 565 lock_fat(sbi); 566 do { 567 cluster = fat_ent_read(inode, &fatent, cluster); 568 if (cluster < 0) { 569 err = cluster; 570 goto error; 571 } else if (cluster == FAT_ENT_FREE) { 572 fat_fs_error(sb, "%s: deleting FAT entry beyond EOF", 573 __func__); 574 err = -EIO; 575 goto error; 576 } 577 578 if (sbi->options.discard) { 579 /* 580 * Issue discard for the sectors we no longer 581 * care about, batching contiguous clusters 582 * into one request 583 */ 584 if (cluster != fatent.entry + 1) { 585 int nr_clus = fatent.entry - first_cl + 1; 586 587 sb_issue_discard(sb, 588 fat_clus_to_blknr(sbi, first_cl), 589 nr_clus * sbi->sec_per_clus, 590 GFP_NOFS, 0); 591 592 first_cl = cluster; 593 } 594 } 595 596 ops->ent_put(&fatent, FAT_ENT_FREE); 597 if (sbi->free_clusters != -1) { 598 sbi->free_clusters++; 599 dirty_fsinfo = 1; 600 } 601 602 if (nr_bhs + fatent.nr_bhs > MAX_BUF_PER_PAGE) { 603 if (sb->s_flags & MS_SYNCHRONOUS) { 604 err = fat_sync_bhs(bhs, nr_bhs); 605 if (err) 606 goto error; 607 } 608 err = fat_mirror_bhs(sb, bhs, nr_bhs); 609 if (err) 610 goto error; 611 for (i = 0; i < nr_bhs; i++) 612 brelse(bhs[i]); 613 nr_bhs = 0; 614 } 615 fat_collect_bhs(bhs, &nr_bhs, &fatent); 616 } while (cluster != FAT_ENT_EOF); 617 618 if (sb->s_flags & MS_SYNCHRONOUS) { 619 err = fat_sync_bhs(bhs, nr_bhs); 620 if (err) 621 goto error; 622 } 623 err = fat_mirror_bhs(sb, bhs, nr_bhs); 624 error: 625 fatent_brelse(&fatent); 626 for (i = 0; i < nr_bhs; i++) 627 brelse(bhs[i]); 628 unlock_fat(sbi); 629 if (dirty_fsinfo) 630 mark_fsinfo_dirty(sb); 631 632 return err; 633 } 634 EXPORT_SYMBOL_GPL(fat_free_clusters); 635 636 /* 128kb is the whole sectors for FAT12 and FAT16 */ 637 #define FAT_READA_SIZE (128 * 1024) 638 639 static void fat_ent_reada(struct super_block *sb, struct fat_entry *fatent, 640 unsigned long reada_blocks) 641 { 642 struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops; 643 sector_t blocknr; 644 int i, offset; 645 646 ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr); 647 648 for (i = 0; i < reada_blocks; i++) 649 sb_breadahead(sb, blocknr + i); 650 } 651 652 int fat_count_free_clusters(struct super_block *sb) 653 { 654 struct msdos_sb_info *sbi = MSDOS_SB(sb); 655 struct fatent_operations *ops = sbi->fatent_ops; 656 struct fat_entry fatent; 657 unsigned long reada_blocks, reada_mask, cur_block; 658 int err = 0, free; 659 660 lock_fat(sbi); 661 if (sbi->free_clusters != -1 && sbi->free_clus_valid) 662 goto out; 663 664 reada_blocks = FAT_READA_SIZE >> sb->s_blocksize_bits; 665 reada_mask = reada_blocks - 1; 666 cur_block = 0; 667 668 free = 0; 669 fatent_init(&fatent); 670 fatent_set_entry(&fatent, FAT_START_ENT); 671 while (fatent.entry < sbi->max_cluster) { 672 /* readahead of fat blocks */ 673 if ((cur_block & reada_mask) == 0) { 674 unsigned long rest = sbi->fat_length - cur_block; 675 fat_ent_reada(sb, &fatent, min(reada_blocks, rest)); 676 } 677 cur_block++; 678 679 err = fat_ent_read_block(sb, &fatent); 680 if (err) 681 goto out; 682 683 do { 684 if (ops->ent_get(&fatent) == FAT_ENT_FREE) 685 free++; 686 } while (fat_ent_next(sbi, &fatent)); 687 } 688 sbi->free_clusters = free; 689 sbi->free_clus_valid = 1; 690 mark_fsinfo_dirty(sb); 691 fatent_brelse(&fatent); 692 out: 693 unlock_fat(sbi); 694 return err; 695 } 696