1/* 2 * Copyright (C) 2004, OGAWA Hirofumi 3 * Released under GPL v2. 4 */ 5 6#include <linux/blkdev.h> 7#include "fat.h" 8 9struct fatent_operations { 10 void (*ent_blocknr)(struct super_block *, int, int *, sector_t *); 11 void (*ent_set_ptr)(struct fat_entry *, int); 12 int (*ent_bread)(struct super_block *, struct fat_entry *, 13 int, sector_t); 14 int (*ent_get)(struct fat_entry *); 15 void (*ent_put)(struct fat_entry *, int); 16 int (*ent_next)(struct fat_entry *); 17}; 18 19static DEFINE_SPINLOCK(fat12_entry_lock); 20 21static void fat12_ent_blocknr(struct super_block *sb, int entry, 22 int *offset, sector_t *blocknr) 23{ 24 struct msdos_sb_info *sbi = MSDOS_SB(sb); 25 int bytes = entry + (entry >> 1); 26 WARN_ON(entry < FAT_START_ENT || sbi->max_cluster <= entry); 27 *offset = bytes & (sb->s_blocksize - 1); 28 *blocknr = sbi->fat_start + (bytes >> sb->s_blocksize_bits); 29} 30 31static void fat_ent_blocknr(struct super_block *sb, int entry, 32 int *offset, sector_t *blocknr) 33{ 34 struct msdos_sb_info *sbi = MSDOS_SB(sb); 35 int bytes = (entry << sbi->fatent_shift); 36 WARN_ON(entry < FAT_START_ENT || sbi->max_cluster <= entry); 37 *offset = bytes & (sb->s_blocksize - 1); 38 *blocknr = sbi->fat_start + (bytes >> sb->s_blocksize_bits); 39} 40 41static void fat12_ent_set_ptr(struct fat_entry *fatent, int offset) 42{ 43 struct buffer_head **bhs = fatent->bhs; 44 if (fatent->nr_bhs == 1) { 45 WARN_ON(offset >= (bhs[0]->b_size - 1)); 46 fatent->u.ent12_p[0] = bhs[0]->b_data + offset; 47 fatent->u.ent12_p[1] = bhs[0]->b_data + (offset + 1); 48 } else { 49 WARN_ON(offset != (bhs[0]->b_size - 1)); 50 fatent->u.ent12_p[0] = bhs[0]->b_data + offset; 51 fatent->u.ent12_p[1] = bhs[1]->b_data; 52 } 53} 54 55static void fat16_ent_set_ptr(struct fat_entry *fatent, int offset) 56{ 57 WARN_ON(offset & (2 - 1)); 58 fatent->u.ent16_p = (__le16 *)(fatent->bhs[0]->b_data + offset); 59} 60 61static void fat32_ent_set_ptr(struct fat_entry *fatent, int offset) 62{ 63 WARN_ON(offset & (4 - 1)); 64 fatent->u.ent32_p = (__le32 *)(fatent->bhs[0]->b_data + offset); 65} 66 67static int fat12_ent_bread(struct super_block *sb, struct fat_entry *fatent, 68 int offset, sector_t blocknr) 69{ 70 struct buffer_head **bhs = fatent->bhs; 71 72 WARN_ON(blocknr < MSDOS_SB(sb)->fat_start); 73 fatent->fat_inode = MSDOS_SB(sb)->fat_inode; 74 75 bhs[0] = sb_bread(sb, blocknr); 76 if (!bhs[0]) 77 goto err; 78 79 if ((offset + 1) < sb->s_blocksize) 80 fatent->nr_bhs = 1; 81 else { 82 /* This entry is block boundary, it needs the next block */ 83 blocknr++; 84 bhs[1] = sb_bread(sb, blocknr); 85 if (!bhs[1]) 86 goto err_brelse; 87 fatent->nr_bhs = 2; 88 } 89 fat12_ent_set_ptr(fatent, offset); 90 return 0; 91 92err_brelse: 93 brelse(bhs[0]); 94err: 95 fat_msg(sb, KERN_ERR, "FAT read failed (blocknr %llu)", (llu)blocknr); 96 return -EIO; 97} 98 99static int fat_ent_bread(struct super_block *sb, struct fat_entry *fatent, 100 int offset, sector_t blocknr) 101{ 102 struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops; 103 104 WARN_ON(blocknr < MSDOS_SB(sb)->fat_start); 105 fatent->fat_inode = MSDOS_SB(sb)->fat_inode; 106 fatent->bhs[0] = sb_bread(sb, blocknr); 107 if (!fatent->bhs[0]) { 108 fat_msg(sb, KERN_ERR, "FAT read failed (blocknr %llu)", 109 (llu)blocknr); 110 return -EIO; 111 } 112 fatent->nr_bhs = 1; 113 ops->ent_set_ptr(fatent, offset); 114 return 0; 115} 116 117static int fat12_ent_get(struct fat_entry *fatent) 118{ 119 u8 **ent12_p = fatent->u.ent12_p; 120 int next; 121 122 spin_lock(&fat12_entry_lock); 123 if (fatent->entry & 1) 124 next = (*ent12_p[0] >> 4) | (*ent12_p[1] << 4); 125 else 126 next = (*ent12_p[1] << 8) | *ent12_p[0]; 127 spin_unlock(&fat12_entry_lock); 128 129 next &= 0x0fff; 130 if (next >= BAD_FAT12) 131 next = FAT_ENT_EOF; 132 return next; 133} 134 135static int fat16_ent_get(struct fat_entry *fatent) 136{ 137 int next = le16_to_cpu(*fatent->u.ent16_p); 138 WARN_ON((unsigned long)fatent->u.ent16_p & (2 - 1)); 139 if (next >= BAD_FAT16) 140 next = FAT_ENT_EOF; 141 return next; 142} 143 144static int fat32_ent_get(struct fat_entry *fatent) 145{ 146 int next = le32_to_cpu(*fatent->u.ent32_p) & 0x0fffffff; 147 WARN_ON((unsigned long)fatent->u.ent32_p & (4 - 1)); 148 if (next >= BAD_FAT32) 149 next = FAT_ENT_EOF; 150 return next; 151} 152 153static void fat12_ent_put(struct fat_entry *fatent, int new) 154{ 155 u8 **ent12_p = fatent->u.ent12_p; 156 157 if (new == FAT_ENT_EOF) 158 new = EOF_FAT12; 159 160 spin_lock(&fat12_entry_lock); 161 if (fatent->entry & 1) { 162 *ent12_p[0] = (new << 4) | (*ent12_p[0] & 0x0f); 163 *ent12_p[1] = new >> 4; 164 } else { 165 *ent12_p[0] = new & 0xff; 166 *ent12_p[1] = (*ent12_p[1] & 0xf0) | (new >> 8); 167 } 168 spin_unlock(&fat12_entry_lock); 169 170 mark_buffer_dirty_inode(fatent->bhs[0], fatent->fat_inode); 171 if (fatent->nr_bhs == 2) 172 mark_buffer_dirty_inode(fatent->bhs[1], fatent->fat_inode); 173} 174 175static void fat16_ent_put(struct fat_entry *fatent, int new) 176{ 177 if (new == FAT_ENT_EOF) 178 new = EOF_FAT16; 179 180 *fatent->u.ent16_p = cpu_to_le16(new); 181 mark_buffer_dirty_inode(fatent->bhs[0], fatent->fat_inode); 182} 183 184static void fat32_ent_put(struct fat_entry *fatent, int new) 185{ 186 WARN_ON(new & 0xf0000000); 187 new |= le32_to_cpu(*fatent->u.ent32_p) & ~0x0fffffff; 188 *fatent->u.ent32_p = cpu_to_le32(new); 189 mark_buffer_dirty_inode(fatent->bhs[0], fatent->fat_inode); 190} 191 192static int fat12_ent_next(struct fat_entry *fatent) 193{ 194 u8 **ent12_p = fatent->u.ent12_p; 195 struct buffer_head **bhs = fatent->bhs; 196 u8 *nextp = ent12_p[1] + 1 + (fatent->entry & 1); 197 198 fatent->entry++; 199 if (fatent->nr_bhs == 1) { 200 WARN_ON(ent12_p[0] > (u8 *)(bhs[0]->b_data + 201 (bhs[0]->b_size - 2))); 202 WARN_ON(ent12_p[1] > (u8 *)(bhs[0]->b_data + 203 (bhs[0]->b_size - 1))); 204 if (nextp < (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 1))) { 205 ent12_p[0] = nextp - 1; 206 ent12_p[1] = nextp; 207 return 1; 208 } 209 } else { 210 WARN_ON(ent12_p[0] != (u8 *)(bhs[0]->b_data + 211 (bhs[0]->b_size - 1))); 212 WARN_ON(ent12_p[1] != (u8 *)bhs[1]->b_data); 213 ent12_p[0] = nextp - 1; 214 ent12_p[1] = nextp; 215 brelse(bhs[0]); 216 bhs[0] = bhs[1]; 217 fatent->nr_bhs = 1; 218 return 1; 219 } 220 ent12_p[0] = NULL; 221 ent12_p[1] = NULL; 222 return 0; 223} 224 225static int fat16_ent_next(struct fat_entry *fatent) 226{ 227 const struct buffer_head *bh = fatent->bhs[0]; 228 fatent->entry++; 229 if (fatent->u.ent16_p < (__le16 *)(bh->b_data + (bh->b_size - 2))) { 230 fatent->u.ent16_p++; 231 return 1; 232 } 233 fatent->u.ent16_p = NULL; 234 return 0; 235} 236 237static int fat32_ent_next(struct fat_entry *fatent) 238{ 239 const struct buffer_head *bh = fatent->bhs[0]; 240 fatent->entry++; 241 if (fatent->u.ent32_p < (__le32 *)(bh->b_data + (bh->b_size - 4))) { 242 fatent->u.ent32_p++; 243 return 1; 244 } 245 fatent->u.ent32_p = NULL; 246 return 0; 247} 248 249static struct fatent_operations fat12_ops = { 250 .ent_blocknr = fat12_ent_blocknr, 251 .ent_set_ptr = fat12_ent_set_ptr, 252 .ent_bread = fat12_ent_bread, 253 .ent_get = fat12_ent_get, 254 .ent_put = fat12_ent_put, 255 .ent_next = fat12_ent_next, 256}; 257 258static struct fatent_operations fat16_ops = { 259 .ent_blocknr = fat_ent_blocknr, 260 .ent_set_ptr = fat16_ent_set_ptr, 261 .ent_bread = fat_ent_bread, 262 .ent_get = fat16_ent_get, 263 .ent_put = fat16_ent_put, 264 .ent_next = fat16_ent_next, 265}; 266 267static struct fatent_operations fat32_ops = { 268 .ent_blocknr = fat_ent_blocknr, 269 .ent_set_ptr = fat32_ent_set_ptr, 270 .ent_bread = fat_ent_bread, 271 .ent_get = fat32_ent_get, 272 .ent_put = fat32_ent_put, 273 .ent_next = fat32_ent_next, 274}; 275 276static inline void lock_fat(struct msdos_sb_info *sbi) 277{ 278 mutex_lock(&sbi->fat_lock); 279} 280 281static inline void unlock_fat(struct msdos_sb_info *sbi) 282{ 283 mutex_unlock(&sbi->fat_lock); 284} 285 286void fat_ent_access_init(struct super_block *sb) 287{ 288 struct msdos_sb_info *sbi = MSDOS_SB(sb); 289 290 mutex_init(&sbi->fat_lock); 291 292 switch (sbi->fat_bits) { 293 case 32: 294 sbi->fatent_shift = 2; 295 sbi->fatent_ops = &fat32_ops; 296 break; 297 case 16: 298 sbi->fatent_shift = 1; 299 sbi->fatent_ops = &fat16_ops; 300 break; 301 case 12: 302 sbi->fatent_shift = -1; 303 sbi->fatent_ops = &fat12_ops; 304 break; 305 } 306} 307 308static void mark_fsinfo_dirty(struct super_block *sb) 309{ 310 struct msdos_sb_info *sbi = MSDOS_SB(sb); 311 312 if (sb->s_flags & MS_RDONLY || sbi->fat_bits != 32) 313 return; 314 315 __mark_inode_dirty(sbi->fsinfo_inode, I_DIRTY_SYNC); 316} 317 318static inline int fat_ent_update_ptr(struct super_block *sb, 319 struct fat_entry *fatent, 320 int offset, sector_t blocknr) 321{ 322 struct msdos_sb_info *sbi = MSDOS_SB(sb); 323 struct fatent_operations *ops = sbi->fatent_ops; 324 struct buffer_head **bhs = fatent->bhs; 325 326 /* Is this fatent's blocks including this entry? */ 327 if (!fatent->nr_bhs || bhs[0]->b_blocknr != blocknr) 328 return 0; 329 if (sbi->fat_bits == 12) { 330 if ((offset + 1) < sb->s_blocksize) { 331 /* This entry is on bhs[0]. */ 332 if (fatent->nr_bhs == 2) { 333 brelse(bhs[1]); 334 fatent->nr_bhs = 1; 335 } 336 } else { 337 /* This entry needs the next block. */ 338 if (fatent->nr_bhs != 2) 339 return 0; 340 if (bhs[1]->b_blocknr != (blocknr + 1)) 341 return 0; 342 } 343 } 344 ops->ent_set_ptr(fatent, offset); 345 return 1; 346} 347 348int fat_ent_read(struct inode *inode, struct fat_entry *fatent, int entry) 349{ 350 struct super_block *sb = inode->i_sb; 351 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb); 352 struct fatent_operations *ops = sbi->fatent_ops; 353 int err, offset; 354 sector_t blocknr; 355 356 if (entry < FAT_START_ENT || sbi->max_cluster <= entry) { 357 fatent_brelse(fatent); 358 fat_fs_error(sb, "invalid access to FAT (entry 0x%08x)", entry); 359 return -EIO; 360 } 361 362 fatent_set_entry(fatent, entry); 363 ops->ent_blocknr(sb, entry, &offset, &blocknr); 364 365 if (!fat_ent_update_ptr(sb, fatent, offset, blocknr)) { 366 fatent_brelse(fatent); 367 err = ops->ent_bread(sb, fatent, offset, blocknr); 368 if (err) 369 return err; 370 } 371 return ops->ent_get(fatent); 372} 373 374/* FIXME: We can write the blocks as more big chunk. */ 375static int fat_mirror_bhs(struct super_block *sb, struct buffer_head **bhs, 376 int nr_bhs) 377{ 378 struct msdos_sb_info *sbi = MSDOS_SB(sb); 379 struct buffer_head *c_bh; 380 int err, n, copy; 381 382 err = 0; 383 for (copy = 1; copy < sbi->fats; copy++) { 384 sector_t backup_fat = sbi->fat_length * copy; 385 386 for (n = 0; n < nr_bhs; n++) { 387 c_bh = sb_getblk(sb, backup_fat + bhs[n]->b_blocknr); 388 if (!c_bh) { 389 err = -ENOMEM; 390 goto error; 391 } 392 memcpy(c_bh->b_data, bhs[n]->b_data, sb->s_blocksize); 393 set_buffer_uptodate(c_bh); 394 mark_buffer_dirty_inode(c_bh, sbi->fat_inode); 395 if (sb->s_flags & MS_SYNCHRONOUS) 396 err = sync_dirty_buffer(c_bh); 397 brelse(c_bh); 398 if (err) 399 goto error; 400 } 401 } 402error: 403 return err; 404} 405 406int fat_ent_write(struct inode *inode, struct fat_entry *fatent, 407 int new, int wait) 408{ 409 struct super_block *sb = inode->i_sb; 410 struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops; 411 int err; 412 413 ops->ent_put(fatent, new); 414 if (wait) { 415 err = fat_sync_bhs(fatent->bhs, fatent->nr_bhs); 416 if (err) 417 return err; 418 } 419 return fat_mirror_bhs(sb, fatent->bhs, fatent->nr_bhs); 420} 421 422static inline int fat_ent_next(struct msdos_sb_info *sbi, 423 struct fat_entry *fatent) 424{ 425 if (sbi->fatent_ops->ent_next(fatent)) { 426 if (fatent->entry < sbi->max_cluster) 427 return 1; 428 } 429 return 0; 430} 431 432static inline int fat_ent_read_block(struct super_block *sb, 433 struct fat_entry *fatent) 434{ 435 struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops; 436 sector_t blocknr; 437 int offset; 438 439 fatent_brelse(fatent); 440 ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr); 441 return ops->ent_bread(sb, fatent, offset, blocknr); 442} 443 444static void fat_collect_bhs(struct buffer_head **bhs, int *nr_bhs, 445 struct fat_entry *fatent) 446{ 447 int n, i; 448 449 for (n = 0; n < fatent->nr_bhs; n++) { 450 for (i = 0; i < *nr_bhs; i++) { 451 if (fatent->bhs[n] == bhs[i]) 452 break; 453 } 454 if (i == *nr_bhs) { 455 get_bh(fatent->bhs[n]); 456 bhs[i] = fatent->bhs[n]; 457 (*nr_bhs)++; 458 } 459 } 460} 461 462int fat_alloc_clusters(struct inode *inode, int *cluster, int nr_cluster) 463{ 464 struct super_block *sb = inode->i_sb; 465 struct msdos_sb_info *sbi = MSDOS_SB(sb); 466 struct fatent_operations *ops = sbi->fatent_ops; 467 struct fat_entry fatent, prev_ent; 468 struct buffer_head *bhs[MAX_BUF_PER_PAGE]; 469 int i, count, err, nr_bhs, idx_clus; 470 471 BUG_ON(nr_cluster > (MAX_BUF_PER_PAGE / 2)); /* fixed limit */ 472 473 lock_fat(sbi); 474 if (sbi->free_clusters != -1 && sbi->free_clus_valid && 475 sbi->free_clusters < nr_cluster) { 476 unlock_fat(sbi); 477 return -ENOSPC; 478 } 479 480 err = nr_bhs = idx_clus = 0; 481 count = FAT_START_ENT; 482 fatent_init(&prev_ent); 483 fatent_init(&fatent); 484 fatent_set_entry(&fatent, sbi->prev_free + 1); 485 while (count < sbi->max_cluster) { 486 if (fatent.entry >= sbi->max_cluster) 487 fatent.entry = FAT_START_ENT; 488 fatent_set_entry(&fatent, fatent.entry); 489 err = fat_ent_read_block(sb, &fatent); 490 if (err) 491 goto out; 492 493 /* Find the free entries in a block */ 494 do { 495 if (ops->ent_get(&fatent) == FAT_ENT_FREE) { 496 int entry = fatent.entry; 497 498 /* make the cluster chain */ 499 ops->ent_put(&fatent, FAT_ENT_EOF); 500 if (prev_ent.nr_bhs) 501 ops->ent_put(&prev_ent, entry); 502 503 fat_collect_bhs(bhs, &nr_bhs, &fatent); 504 505 sbi->prev_free = entry; 506 if (sbi->free_clusters != -1) 507 sbi->free_clusters--; 508 509 cluster[idx_clus] = entry; 510 idx_clus++; 511 if (idx_clus == nr_cluster) 512 goto out; 513 514 /* 515 * fat_collect_bhs() gets ref-count of bhs, 516 * so we can still use the prev_ent. 517 */ 518 prev_ent = fatent; 519 } 520 count++; 521 if (count == sbi->max_cluster) 522 break; 523 } while (fat_ent_next(sbi, &fatent)); 524 } 525 526 /* Couldn't allocate the free entries */ 527 sbi->free_clusters = 0; 528 sbi->free_clus_valid = 1; 529 err = -ENOSPC; 530 531out: 532 unlock_fat(sbi); 533 mark_fsinfo_dirty(sb); 534 fatent_brelse(&fatent); 535 if (!err) { 536 if (inode_needs_sync(inode)) 537 err = fat_sync_bhs(bhs, nr_bhs); 538 if (!err) 539 err = fat_mirror_bhs(sb, bhs, nr_bhs); 540 } 541 for (i = 0; i < nr_bhs; i++) 542 brelse(bhs[i]); 543 544 if (err && idx_clus) 545 fat_free_clusters(inode, cluster[0]); 546 547 return err; 548} 549 550int fat_free_clusters(struct inode *inode, int cluster) 551{ 552 struct super_block *sb = inode->i_sb; 553 struct msdos_sb_info *sbi = MSDOS_SB(sb); 554 struct fatent_operations *ops = sbi->fatent_ops; 555 struct fat_entry fatent; 556 struct buffer_head *bhs[MAX_BUF_PER_PAGE]; 557 int i, err, nr_bhs; 558 int first_cl = cluster, dirty_fsinfo = 0; 559 560 nr_bhs = 0; 561 fatent_init(&fatent); 562 lock_fat(sbi); 563 do { 564 cluster = fat_ent_read(inode, &fatent, cluster); 565 if (cluster < 0) { 566 err = cluster; 567 goto error; 568 } else if (cluster == FAT_ENT_FREE) { 569 fat_fs_error(sb, "%s: deleting FAT entry beyond EOF", 570 __func__); 571 err = -EIO; 572 goto error; 573 } 574 575 if (sbi->options.discard) { 576 /* 577 * Issue discard for the sectors we no longer 578 * care about, batching contiguous clusters 579 * into one request 580 */ 581 if (cluster != fatent.entry + 1) { 582 int nr_clus = fatent.entry - first_cl + 1; 583 584 sb_issue_discard(sb, 585 fat_clus_to_blknr(sbi, first_cl), 586 nr_clus * sbi->sec_per_clus, 587 GFP_NOFS, 0); 588 589 first_cl = cluster; 590 } 591 } 592 593 ops->ent_put(&fatent, FAT_ENT_FREE); 594 if (sbi->free_clusters != -1) { 595 sbi->free_clusters++; 596 dirty_fsinfo = 1; 597 } 598 599 if (nr_bhs + fatent.nr_bhs > MAX_BUF_PER_PAGE) { 600 if (sb->s_flags & MS_SYNCHRONOUS) { 601 err = fat_sync_bhs(bhs, nr_bhs); 602 if (err) 603 goto error; 604 } 605 err = fat_mirror_bhs(sb, bhs, nr_bhs); 606 if (err) 607 goto error; 608 for (i = 0; i < nr_bhs; i++) 609 brelse(bhs[i]); 610 nr_bhs = 0; 611 } 612 fat_collect_bhs(bhs, &nr_bhs, &fatent); 613 } while (cluster != FAT_ENT_EOF); 614 615 if (sb->s_flags & MS_SYNCHRONOUS) { 616 err = fat_sync_bhs(bhs, nr_bhs); 617 if (err) 618 goto error; 619 } 620 err = fat_mirror_bhs(sb, bhs, nr_bhs); 621error: 622 fatent_brelse(&fatent); 623 for (i = 0; i < nr_bhs; i++) 624 brelse(bhs[i]); 625 unlock_fat(sbi); 626 if (dirty_fsinfo) 627 mark_fsinfo_dirty(sb); 628 629 return err; 630} 631EXPORT_SYMBOL_GPL(fat_free_clusters); 632 633/* 128kb is the whole sectors for FAT12 and FAT16 */ 634#define FAT_READA_SIZE (128 * 1024) 635 636static void fat_ent_reada(struct super_block *sb, struct fat_entry *fatent, 637 unsigned long reada_blocks) 638{ 639 struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops; 640 sector_t blocknr; 641 int i, offset; 642 643 ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr); 644 645 for (i = 0; i < reada_blocks; i++) 646 sb_breadahead(sb, blocknr + i); 647} 648 649int fat_count_free_clusters(struct super_block *sb) 650{ 651 struct msdos_sb_info *sbi = MSDOS_SB(sb); 652 struct fatent_operations *ops = sbi->fatent_ops; 653 struct fat_entry fatent; 654 unsigned long reada_blocks, reada_mask, cur_block; 655 int err = 0, free; 656 657 lock_fat(sbi); 658 if (sbi->free_clusters != -1 && sbi->free_clus_valid) 659 goto out; 660 661 reada_blocks = FAT_READA_SIZE >> sb->s_blocksize_bits; 662 reada_mask = reada_blocks - 1; 663 cur_block = 0; 664 665 free = 0; 666 fatent_init(&fatent); 667 fatent_set_entry(&fatent, FAT_START_ENT); 668 while (fatent.entry < sbi->max_cluster) { 669 /* readahead of fat blocks */ 670 if ((cur_block & reada_mask) == 0) { 671 unsigned long rest = sbi->fat_length - cur_block; 672 fat_ent_reada(sb, &fatent, min(reada_blocks, rest)); 673 } 674 cur_block++; 675 676 err = fat_ent_read_block(sb, &fatent); 677 if (err) 678 goto out; 679 680 do { 681 if (ops->ent_get(&fatent) == FAT_ENT_FREE) 682 free++; 683 } while (fat_ent_next(sbi, &fatent)); 684 } 685 sbi->free_clusters = free; 686 sbi->free_clus_valid = 1; 687 mark_fsinfo_dirty(sb); 688 fatent_brelse(&fatent); 689out: 690 unlock_fat(sbi); 691 return err; 692} 693