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