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 bhs[0] = sb_bread(sb, blocknr); 77 if (!bhs[0]) 78 goto err; 79 80 if ((offset + 1) < sb->s_blocksize) 81 fatent->nr_bhs = 1; 82 else { 83 /* This entry is block boundary, it needs the next block */ 84 blocknr++; 85 bhs[1] = sb_bread(sb, blocknr); 86 if (!bhs[1]) 87 goto err_brelse; 88 fatent->nr_bhs = 2; 89 } 90 fat12_ent_set_ptr(fatent, offset); 91 return 0; 92 93 err_brelse: 94 brelse(bhs[0]); 95 err: 96 printk(KERN_ERR "FAT: FAT read failed (blocknr %llu)\n", (llu)blocknr); 97 return -EIO; 98 } 99 100 static int fat_ent_bread(struct super_block *sb, struct fat_entry *fatent, 101 int offset, sector_t blocknr) 102 { 103 struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops; 104 105 WARN_ON(blocknr < MSDOS_SB(sb)->fat_start); 106 fatent->bhs[0] = sb_bread(sb, blocknr); 107 if (!fatent->bhs[0]) { 108 printk(KERN_ERR "FAT: FAT read failed (blocknr %llu)\n", 109 (llu)blocknr); 110 return -EIO; 111 } 112 fatent->nr_bhs = 1; 113 ops->ent_set_ptr(fatent, offset); 114 return 0; 115 } 116 117 static 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 } 134 135 static 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 } 143 144 static 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 } 152 153 static 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(fatent->bhs[0]); 171 if (fatent->nr_bhs == 2) 172 mark_buffer_dirty(fatent->bhs[1]); 173 } 174 175 static 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(fatent->bhs[0]); 182 } 183 184 static void fat32_ent_put(struct fat_entry *fatent, int new) 185 { 186 if (new == FAT_ENT_EOF) 187 new = EOF_FAT32; 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(fatent->bhs[0]); 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 + (bhs[0]->b_size - 2))); 204 WARN_ON(ent12_p[1] > (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 1))); 205 if (nextp < (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 1))) { 206 ent12_p[0] = nextp - 1; 207 ent12_p[1] = nextp; 208 return 1; 209 } 210 } else { 211 WARN_ON(ent12_p[0] != (u8 *)(bhs[0]->b_data + (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 } 224 225 static 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 } 236 237 static 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 } 248 249 static 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 }; 257 258 static 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 }; 266 267 static 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 }; 275 276 static inline void lock_fat(struct msdos_sb_info *sbi) 277 { 278 mutex_lock(&sbi->fat_lock); 279 } 280 281 static inline void unlock_fat(struct msdos_sb_info *sbi) 282 { 283 mutex_unlock(&sbi->fat_lock); 284 } 285 286 void 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 } 307 308 static inline int fat_ent_update_ptr(struct super_block *sb, 309 struct fat_entry *fatent, 310 int offset, sector_t blocknr) 311 { 312 struct msdos_sb_info *sbi = MSDOS_SB(sb); 313 struct fatent_operations *ops = sbi->fatent_ops; 314 struct buffer_head **bhs = fatent->bhs; 315 316 /* Is this fatent's blocks including this entry? */ 317 if (!fatent->nr_bhs || bhs[0]->b_blocknr != blocknr) 318 return 0; 319 if (sbi->fat_bits == 12) { 320 if ((offset + 1) < sb->s_blocksize) { 321 /* This entry is on bhs[0]. */ 322 if (fatent->nr_bhs == 2) { 323 brelse(bhs[1]); 324 fatent->nr_bhs = 1; 325 } 326 } else { 327 /* This entry needs the next block. */ 328 if (fatent->nr_bhs != 2) 329 return 0; 330 if (bhs[1]->b_blocknr != (blocknr + 1)) 331 return 0; 332 } 333 } 334 ops->ent_set_ptr(fatent, offset); 335 return 1; 336 } 337 338 int fat_ent_read(struct inode *inode, struct fat_entry *fatent, int entry) 339 { 340 struct super_block *sb = inode->i_sb; 341 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb); 342 struct fatent_operations *ops = sbi->fatent_ops; 343 int err, offset; 344 sector_t blocknr; 345 346 if (entry < FAT_START_ENT || sbi->max_cluster <= entry) { 347 fatent_brelse(fatent); 348 fat_fs_panic(sb, "invalid access to FAT (entry 0x%08x)", entry); 349 return -EIO; 350 } 351 352 fatent_set_entry(fatent, entry); 353 ops->ent_blocknr(sb, entry, &offset, &blocknr); 354 355 if (!fat_ent_update_ptr(sb, fatent, offset, blocknr)) { 356 fatent_brelse(fatent); 357 err = ops->ent_bread(sb, fatent, offset, blocknr); 358 if (err) 359 return err; 360 } 361 return ops->ent_get(fatent); 362 } 363 364 /* FIXME: We can write the blocks as more big chunk. */ 365 static int fat_mirror_bhs(struct super_block *sb, struct buffer_head **bhs, 366 int nr_bhs) 367 { 368 struct msdos_sb_info *sbi = MSDOS_SB(sb); 369 struct buffer_head *c_bh; 370 int err, n, copy; 371 372 err = 0; 373 for (copy = 1; copy < sbi->fats; copy++) { 374 sector_t backup_fat = sbi->fat_length * copy; 375 376 for (n = 0; n < nr_bhs; n++) { 377 c_bh = sb_getblk(sb, backup_fat + bhs[n]->b_blocknr); 378 if (!c_bh) { 379 err = -ENOMEM; 380 goto error; 381 } 382 memcpy(c_bh->b_data, bhs[n]->b_data, sb->s_blocksize); 383 set_buffer_uptodate(c_bh); 384 mark_buffer_dirty(c_bh); 385 if (sb->s_flags & MS_SYNCHRONOUS) 386 err = sync_dirty_buffer(c_bh); 387 brelse(c_bh); 388 if (err) 389 goto error; 390 } 391 } 392 error: 393 return err; 394 } 395 396 int fat_ent_write(struct inode *inode, struct fat_entry *fatent, 397 int new, int wait) 398 { 399 struct super_block *sb = inode->i_sb; 400 struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops; 401 int err; 402 403 ops->ent_put(fatent, new); 404 if (wait) { 405 err = fat_sync_bhs(fatent->bhs, fatent->nr_bhs); 406 if (err) 407 return err; 408 } 409 return fat_mirror_bhs(sb, fatent->bhs, fatent->nr_bhs); 410 } 411 412 static inline int fat_ent_next(struct msdos_sb_info *sbi, 413 struct fat_entry *fatent) 414 { 415 if (sbi->fatent_ops->ent_next(fatent)) { 416 if (fatent->entry < sbi->max_cluster) 417 return 1; 418 } 419 return 0; 420 } 421 422 static inline int fat_ent_read_block(struct super_block *sb, 423 struct fat_entry *fatent) 424 { 425 struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops; 426 sector_t blocknr; 427 int offset; 428 429 fatent_brelse(fatent); 430 ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr); 431 return ops->ent_bread(sb, fatent, offset, blocknr); 432 } 433 434 static void fat_collect_bhs(struct buffer_head **bhs, int *nr_bhs, 435 struct fat_entry *fatent) 436 { 437 int n, i; 438 439 for (n = 0; n < fatent->nr_bhs; n++) { 440 for (i = 0; i < *nr_bhs; i++) { 441 if (fatent->bhs[n] == bhs[i]) 442 break; 443 } 444 if (i == *nr_bhs) { 445 get_bh(fatent->bhs[n]); 446 bhs[i] = fatent->bhs[n]; 447 (*nr_bhs)++; 448 } 449 } 450 } 451 452 int fat_alloc_clusters(struct inode *inode, int *cluster, int nr_cluster) 453 { 454 struct super_block *sb = inode->i_sb; 455 struct msdos_sb_info *sbi = MSDOS_SB(sb); 456 struct fatent_operations *ops = sbi->fatent_ops; 457 struct fat_entry fatent, prev_ent; 458 struct buffer_head *bhs[MAX_BUF_PER_PAGE]; 459 int i, count, err, nr_bhs, idx_clus; 460 461 BUG_ON(nr_cluster > (MAX_BUF_PER_PAGE / 2)); /* fixed limit */ 462 463 lock_fat(sbi); 464 if (sbi->free_clusters != -1 && sbi->free_clus_valid && 465 sbi->free_clusters < nr_cluster) { 466 unlock_fat(sbi); 467 return -ENOSPC; 468 } 469 470 err = nr_bhs = idx_clus = 0; 471 count = FAT_START_ENT; 472 fatent_init(&prev_ent); 473 fatent_init(&fatent); 474 fatent_set_entry(&fatent, sbi->prev_free + 1); 475 while (count < sbi->max_cluster) { 476 if (fatent.entry >= sbi->max_cluster) 477 fatent.entry = FAT_START_ENT; 478 fatent_set_entry(&fatent, fatent.entry); 479 err = fat_ent_read_block(sb, &fatent); 480 if (err) 481 goto out; 482 483 /* Find the free entries in a block */ 484 do { 485 if (ops->ent_get(&fatent) == FAT_ENT_FREE) { 486 int entry = fatent.entry; 487 488 /* make the cluster chain */ 489 ops->ent_put(&fatent, FAT_ENT_EOF); 490 if (prev_ent.nr_bhs) 491 ops->ent_put(&prev_ent, entry); 492 493 fat_collect_bhs(bhs, &nr_bhs, &fatent); 494 495 sbi->prev_free = entry; 496 if (sbi->free_clusters != -1) 497 sbi->free_clusters--; 498 sb->s_dirt = 1; 499 500 cluster[idx_clus] = entry; 501 idx_clus++; 502 if (idx_clus == nr_cluster) 503 goto out; 504 505 /* 506 * fat_collect_bhs() gets ref-count of bhs, 507 * so we can still use the prev_ent. 508 */ 509 prev_ent = fatent; 510 } 511 count++; 512 if (count == sbi->max_cluster) 513 break; 514 } while (fat_ent_next(sbi, &fatent)); 515 } 516 517 /* Couldn't allocate the free entries */ 518 sbi->free_clusters = 0; 519 sbi->free_clus_valid = 1; 520 sb->s_dirt = 1; 521 err = -ENOSPC; 522 523 out: 524 unlock_fat(sbi); 525 fatent_brelse(&fatent); 526 if (!err) { 527 if (inode_needs_sync(inode)) 528 err = fat_sync_bhs(bhs, nr_bhs); 529 if (!err) 530 err = fat_mirror_bhs(sb, bhs, nr_bhs); 531 } 532 for (i = 0; i < nr_bhs; i++) 533 brelse(bhs[i]); 534 535 if (err && idx_clus) 536 fat_free_clusters(inode, cluster[0]); 537 538 return err; 539 } 540 541 int fat_free_clusters(struct inode *inode, int cluster) 542 { 543 struct super_block *sb = inode->i_sb; 544 struct msdos_sb_info *sbi = MSDOS_SB(sb); 545 struct fatent_operations *ops = sbi->fatent_ops; 546 struct fat_entry fatent; 547 struct buffer_head *bhs[MAX_BUF_PER_PAGE]; 548 int i, err, nr_bhs; 549 int first_cl = cluster; 550 551 nr_bhs = 0; 552 fatent_init(&fatent); 553 lock_fat(sbi); 554 do { 555 cluster = fat_ent_read(inode, &fatent, cluster); 556 if (cluster < 0) { 557 err = cluster; 558 goto error; 559 } else if (cluster == FAT_ENT_FREE) { 560 fat_fs_panic(sb, "%s: deleting FAT entry beyond EOF", 561 __func__); 562 err = -EIO; 563 goto error; 564 } 565 566 /* 567 * Issue discard for the sectors we no longer care about, 568 * batching contiguous clusters into one request 569 */ 570 if (cluster != fatent.entry + 1) { 571 int nr_clus = fatent.entry - first_cl + 1; 572 573 sb_issue_discard(sb, fat_clus_to_blknr(sbi, first_cl), 574 nr_clus * sbi->sec_per_clus); 575 first_cl = cluster; 576 } 577 578 ops->ent_put(&fatent, FAT_ENT_FREE); 579 if (sbi->free_clusters != -1) { 580 sbi->free_clusters++; 581 sb->s_dirt = 1; 582 } 583 584 if (nr_bhs + fatent.nr_bhs > MAX_BUF_PER_PAGE) { 585 if (sb->s_flags & MS_SYNCHRONOUS) { 586 err = fat_sync_bhs(bhs, nr_bhs); 587 if (err) 588 goto error; 589 } 590 err = fat_mirror_bhs(sb, bhs, nr_bhs); 591 if (err) 592 goto error; 593 for (i = 0; i < nr_bhs; i++) 594 brelse(bhs[i]); 595 nr_bhs = 0; 596 } 597 fat_collect_bhs(bhs, &nr_bhs, &fatent); 598 } while (cluster != FAT_ENT_EOF); 599 600 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 error: 607 fatent_brelse(&fatent); 608 for (i = 0; i < nr_bhs; i++) 609 brelse(bhs[i]); 610 unlock_fat(sbi); 611 612 return err; 613 } 614 615 EXPORT_SYMBOL_GPL(fat_free_clusters); 616 617 /* 128kb is the whole sectors for FAT12 and FAT16 */ 618 #define FAT_READA_SIZE (128 * 1024) 619 620 static void fat_ent_reada(struct super_block *sb, struct fat_entry *fatent, 621 unsigned long reada_blocks) 622 { 623 struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops; 624 sector_t blocknr; 625 int i, offset; 626 627 ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr); 628 629 for (i = 0; i < reada_blocks; i++) 630 sb_breadahead(sb, blocknr + i); 631 } 632 633 int fat_count_free_clusters(struct super_block *sb) 634 { 635 struct msdos_sb_info *sbi = MSDOS_SB(sb); 636 struct fatent_operations *ops = sbi->fatent_ops; 637 struct fat_entry fatent; 638 unsigned long reada_blocks, reada_mask, cur_block; 639 int err = 0, free; 640 641 lock_fat(sbi); 642 if (sbi->free_clusters != -1 && sbi->free_clus_valid) 643 goto out; 644 645 reada_blocks = FAT_READA_SIZE >> sb->s_blocksize_bits; 646 reada_mask = reada_blocks - 1; 647 cur_block = 0; 648 649 free = 0; 650 fatent_init(&fatent); 651 fatent_set_entry(&fatent, FAT_START_ENT); 652 while (fatent.entry < sbi->max_cluster) { 653 /* readahead of fat blocks */ 654 if ((cur_block & reada_mask) == 0) { 655 unsigned long rest = sbi->fat_length - cur_block; 656 fat_ent_reada(sb, &fatent, min(reada_blocks, rest)); 657 } 658 cur_block++; 659 660 err = fat_ent_read_block(sb, &fatent); 661 if (err) 662 goto out; 663 664 do { 665 if (ops->ent_get(&fatent) == FAT_ENT_FREE) 666 free++; 667 } while (fat_ent_next(sbi, &fatent)); 668 } 669 sbi->free_clusters = free; 670 sbi->free_clus_valid = 1; 671 sb->s_dirt = 1; 672 fatent_brelse(&fatent); 673 out: 674 unlock_fat(sbi); 675 return err; 676 } 677