1 /* 2 * Copyright (C) 2004, OGAWA Hirofumi 3 * Released under GPL v2. 4 */ 5 6 #include <linux/blkdev.h> 7 #include <linux/sched/signal.h> 8 #include "fat.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 DEFINE_SPINLOCK(fat12_entry_lock); 21 22 static void fat12_ent_blocknr(struct super_block *sb, int entry, 23 int *offset, sector_t *blocknr) 24 { 25 struct msdos_sb_info *sbi = MSDOS_SB(sb); 26 int bytes = entry + (entry >> 1); 27 WARN_ON(!fat_valid_entry(sbi, entry)); 28 *offset = bytes & (sb->s_blocksize - 1); 29 *blocknr = sbi->fat_start + (bytes >> sb->s_blocksize_bits); 30 } 31 32 static void fat_ent_blocknr(struct super_block *sb, int entry, 33 int *offset, sector_t *blocknr) 34 { 35 struct msdos_sb_info *sbi = MSDOS_SB(sb); 36 int bytes = (entry << sbi->fatent_shift); 37 WARN_ON(!fat_valid_entry(sbi, entry)); 38 *offset = bytes & (sb->s_blocksize - 1); 39 *blocknr = sbi->fat_start + (bytes >> sb->s_blocksize_bits); 40 } 41 42 static void fat12_ent_set_ptr(struct fat_entry *fatent, int offset) 43 { 44 struct buffer_head **bhs = fatent->bhs; 45 if (fatent->nr_bhs == 1) { 46 WARN_ON(offset >= (bhs[0]->b_size - 1)); 47 fatent->u.ent12_p[0] = bhs[0]->b_data + offset; 48 fatent->u.ent12_p[1] = bhs[0]->b_data + (offset + 1); 49 } else { 50 WARN_ON(offset != (bhs[0]->b_size - 1)); 51 fatent->u.ent12_p[0] = bhs[0]->b_data + offset; 52 fatent->u.ent12_p[1] = bhs[1]->b_data; 53 } 54 } 55 56 static void fat16_ent_set_ptr(struct fat_entry *fatent, int offset) 57 { 58 WARN_ON(offset & (2 - 1)); 59 fatent->u.ent16_p = (__le16 *)(fatent->bhs[0]->b_data + offset); 60 } 61 62 static void fat32_ent_set_ptr(struct fat_entry *fatent, int offset) 63 { 64 WARN_ON(offset & (4 - 1)); 65 fatent->u.ent32_p = (__le32 *)(fatent->bhs[0]->b_data + offset); 66 } 67 68 static int fat12_ent_bread(struct super_block *sb, struct fat_entry *fatent, 69 int offset, sector_t blocknr) 70 { 71 struct buffer_head **bhs = fatent->bhs; 72 73 WARN_ON(blocknr < MSDOS_SB(sb)->fat_start); 74 fatent->fat_inode = MSDOS_SB(sb)->fat_inode; 75 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 fat_msg(sb, KERN_ERR, "FAT read failed (blocknr %llu)", (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 const struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops; 104 105 WARN_ON(blocknr < MSDOS_SB(sb)->fat_start); 106 fatent->fat_inode = MSDOS_SB(sb)->fat_inode; 107 fatent->bhs[0] = sb_bread(sb, blocknr); 108 if (!fatent->bhs[0]) { 109 fat_msg(sb, KERN_ERR, "FAT read failed (blocknr %llu)", 110 (llu)blocknr); 111 return -EIO; 112 } 113 fatent->nr_bhs = 1; 114 ops->ent_set_ptr(fatent, offset); 115 return 0; 116 } 117 118 static int fat12_ent_get(struct fat_entry *fatent) 119 { 120 u8 **ent12_p = fatent->u.ent12_p; 121 int next; 122 123 spin_lock(&fat12_entry_lock); 124 if (fatent->entry & 1) 125 next = (*ent12_p[0] >> 4) | (*ent12_p[1] << 4); 126 else 127 next = (*ent12_p[1] << 8) | *ent12_p[0]; 128 spin_unlock(&fat12_entry_lock); 129 130 next &= 0x0fff; 131 if (next >= BAD_FAT12) 132 next = FAT_ENT_EOF; 133 return next; 134 } 135 136 static int fat16_ent_get(struct fat_entry *fatent) 137 { 138 int next = le16_to_cpu(*fatent->u.ent16_p); 139 WARN_ON((unsigned long)fatent->u.ent16_p & (2 - 1)); 140 if (next >= BAD_FAT16) 141 next = FAT_ENT_EOF; 142 return next; 143 } 144 145 static int fat32_ent_get(struct fat_entry *fatent) 146 { 147 int next = le32_to_cpu(*fatent->u.ent32_p) & 0x0fffffff; 148 WARN_ON((unsigned long)fatent->u.ent32_p & (4 - 1)); 149 if (next >= BAD_FAT32) 150 next = FAT_ENT_EOF; 151 return next; 152 } 153 154 static void fat12_ent_put(struct fat_entry *fatent, int new) 155 { 156 u8 **ent12_p = fatent->u.ent12_p; 157 158 if (new == FAT_ENT_EOF) 159 new = EOF_FAT12; 160 161 spin_lock(&fat12_entry_lock); 162 if (fatent->entry & 1) { 163 *ent12_p[0] = (new << 4) | (*ent12_p[0] & 0x0f); 164 *ent12_p[1] = new >> 4; 165 } else { 166 *ent12_p[0] = new & 0xff; 167 *ent12_p[1] = (*ent12_p[1] & 0xf0) | (new >> 8); 168 } 169 spin_unlock(&fat12_entry_lock); 170 171 mark_buffer_dirty_inode(fatent->bhs[0], fatent->fat_inode); 172 if (fatent->nr_bhs == 2) 173 mark_buffer_dirty_inode(fatent->bhs[1], fatent->fat_inode); 174 } 175 176 static void fat16_ent_put(struct fat_entry *fatent, int new) 177 { 178 if (new == FAT_ENT_EOF) 179 new = EOF_FAT16; 180 181 *fatent->u.ent16_p = cpu_to_le16(new); 182 mark_buffer_dirty_inode(fatent->bhs[0], fatent->fat_inode); 183 } 184 185 static void fat32_ent_put(struct fat_entry *fatent, int new) 186 { 187 WARN_ON(new & 0xf0000000); 188 new |= le32_to_cpu(*fatent->u.ent32_p) & ~0x0fffffff; 189 *fatent->u.ent32_p = cpu_to_le32(new); 190 mark_buffer_dirty_inode(fatent->bhs[0], fatent->fat_inode); 191 } 192 193 static int fat12_ent_next(struct fat_entry *fatent) 194 { 195 u8 **ent12_p = fatent->u.ent12_p; 196 struct buffer_head **bhs = fatent->bhs; 197 u8 *nextp = ent12_p[1] + 1 + (fatent->entry & 1); 198 199 fatent->entry++; 200 if (fatent->nr_bhs == 1) { 201 WARN_ON(ent12_p[0] > (u8 *)(bhs[0]->b_data + 202 (bhs[0]->b_size - 2))); 203 WARN_ON(ent12_p[1] > (u8 *)(bhs[0]->b_data + 204 (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 + 212 (bhs[0]->b_size - 1))); 213 WARN_ON(ent12_p[1] != (u8 *)bhs[1]->b_data); 214 ent12_p[0] = nextp - 1; 215 ent12_p[1] = nextp; 216 brelse(bhs[0]); 217 bhs[0] = bhs[1]; 218 fatent->nr_bhs = 1; 219 return 1; 220 } 221 ent12_p[0] = NULL; 222 ent12_p[1] = NULL; 223 return 0; 224 } 225 226 static int fat16_ent_next(struct fat_entry *fatent) 227 { 228 const struct buffer_head *bh = fatent->bhs[0]; 229 fatent->entry++; 230 if (fatent->u.ent16_p < (__le16 *)(bh->b_data + (bh->b_size - 2))) { 231 fatent->u.ent16_p++; 232 return 1; 233 } 234 fatent->u.ent16_p = NULL; 235 return 0; 236 } 237 238 static int fat32_ent_next(struct fat_entry *fatent) 239 { 240 const struct buffer_head *bh = fatent->bhs[0]; 241 fatent->entry++; 242 if (fatent->u.ent32_p < (__le32 *)(bh->b_data + (bh->b_size - 4))) { 243 fatent->u.ent32_p++; 244 return 1; 245 } 246 fatent->u.ent32_p = NULL; 247 return 0; 248 } 249 250 static const struct fatent_operations fat12_ops = { 251 .ent_blocknr = fat12_ent_blocknr, 252 .ent_set_ptr = fat12_ent_set_ptr, 253 .ent_bread = fat12_ent_bread, 254 .ent_get = fat12_ent_get, 255 .ent_put = fat12_ent_put, 256 .ent_next = fat12_ent_next, 257 }; 258 259 static const struct fatent_operations fat16_ops = { 260 .ent_blocknr = fat_ent_blocknr, 261 .ent_set_ptr = fat16_ent_set_ptr, 262 .ent_bread = fat_ent_bread, 263 .ent_get = fat16_ent_get, 264 .ent_put = fat16_ent_put, 265 .ent_next = fat16_ent_next, 266 }; 267 268 static const struct fatent_operations fat32_ops = { 269 .ent_blocknr = fat_ent_blocknr, 270 .ent_set_ptr = fat32_ent_set_ptr, 271 .ent_bread = fat_ent_bread, 272 .ent_get = fat32_ent_get, 273 .ent_put = fat32_ent_put, 274 .ent_next = fat32_ent_next, 275 }; 276 277 static inline void lock_fat(struct msdos_sb_info *sbi) 278 { 279 mutex_lock(&sbi->fat_lock); 280 } 281 282 static inline void unlock_fat(struct msdos_sb_info *sbi) 283 { 284 mutex_unlock(&sbi->fat_lock); 285 } 286 287 void fat_ent_access_init(struct super_block *sb) 288 { 289 struct msdos_sb_info *sbi = MSDOS_SB(sb); 290 291 mutex_init(&sbi->fat_lock); 292 293 switch (sbi->fat_bits) { 294 case 32: 295 sbi->fatent_shift = 2; 296 sbi->fatent_ops = &fat32_ops; 297 break; 298 case 16: 299 sbi->fatent_shift = 1; 300 sbi->fatent_ops = &fat16_ops; 301 break; 302 case 12: 303 sbi->fatent_shift = -1; 304 sbi->fatent_ops = &fat12_ops; 305 break; 306 } 307 } 308 309 static void mark_fsinfo_dirty(struct super_block *sb) 310 { 311 struct msdos_sb_info *sbi = MSDOS_SB(sb); 312 313 if (sb_rdonly(sb) || sbi->fat_bits != 32) 314 return; 315 316 __mark_inode_dirty(sbi->fsinfo_inode, I_DIRTY_SYNC); 317 } 318 319 static inline int fat_ent_update_ptr(struct super_block *sb, 320 struct fat_entry *fatent, 321 int offset, sector_t blocknr) 322 { 323 struct msdos_sb_info *sbi = MSDOS_SB(sb); 324 const struct fatent_operations *ops = sbi->fatent_ops; 325 struct buffer_head **bhs = fatent->bhs; 326 327 /* Is this fatent's blocks including this entry? */ 328 if (!fatent->nr_bhs || bhs[0]->b_blocknr != blocknr) 329 return 0; 330 if (sbi->fat_bits == 12) { 331 if ((offset + 1) < sb->s_blocksize) { 332 /* This entry is on bhs[0]. */ 333 if (fatent->nr_bhs == 2) { 334 brelse(bhs[1]); 335 fatent->nr_bhs = 1; 336 } 337 } else { 338 /* This entry needs the next block. */ 339 if (fatent->nr_bhs != 2) 340 return 0; 341 if (bhs[1]->b_blocknr != (blocknr + 1)) 342 return 0; 343 } 344 } 345 ops->ent_set_ptr(fatent, offset); 346 return 1; 347 } 348 349 int fat_ent_read(struct inode *inode, struct fat_entry *fatent, int entry) 350 { 351 struct super_block *sb = inode->i_sb; 352 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb); 353 const struct fatent_operations *ops = sbi->fatent_ops; 354 int err, offset; 355 sector_t blocknr; 356 357 if (!fat_valid_entry(sbi, entry)) { 358 fatent_brelse(fatent); 359 fat_fs_error(sb, "invalid access to FAT (entry 0x%08x)", entry); 360 return -EIO; 361 } 362 363 fatent_set_entry(fatent, entry); 364 ops->ent_blocknr(sb, entry, &offset, &blocknr); 365 366 if (!fat_ent_update_ptr(sb, fatent, offset, blocknr)) { 367 fatent_brelse(fatent); 368 err = ops->ent_bread(sb, fatent, offset, blocknr); 369 if (err) 370 return err; 371 } 372 return ops->ent_get(fatent); 373 } 374 375 /* FIXME: We can write the blocks as more big chunk. */ 376 static int fat_mirror_bhs(struct super_block *sb, struct buffer_head **bhs, 377 int nr_bhs) 378 { 379 struct msdos_sb_info *sbi = MSDOS_SB(sb); 380 struct buffer_head *c_bh; 381 int err, n, copy; 382 383 err = 0; 384 for (copy = 1; copy < sbi->fats; copy++) { 385 sector_t backup_fat = sbi->fat_length * copy; 386 387 for (n = 0; n < nr_bhs; n++) { 388 c_bh = sb_getblk(sb, backup_fat + bhs[n]->b_blocknr); 389 if (!c_bh) { 390 err = -ENOMEM; 391 goto error; 392 } 393 memcpy(c_bh->b_data, bhs[n]->b_data, sb->s_blocksize); 394 set_buffer_uptodate(c_bh); 395 mark_buffer_dirty_inode(c_bh, sbi->fat_inode); 396 if (sb->s_flags & SB_SYNCHRONOUS) 397 err = sync_dirty_buffer(c_bh); 398 brelse(c_bh); 399 if (err) 400 goto error; 401 } 402 } 403 error: 404 return err; 405 } 406 407 int fat_ent_write(struct inode *inode, struct fat_entry *fatent, 408 int new, int wait) 409 { 410 struct super_block *sb = inode->i_sb; 411 const struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops; 412 int err; 413 414 ops->ent_put(fatent, new); 415 if (wait) { 416 err = fat_sync_bhs(fatent->bhs, fatent->nr_bhs); 417 if (err) 418 return err; 419 } 420 return fat_mirror_bhs(sb, fatent->bhs, fatent->nr_bhs); 421 } 422 423 static inline int fat_ent_next(struct msdos_sb_info *sbi, 424 struct fat_entry *fatent) 425 { 426 if (sbi->fatent_ops->ent_next(fatent)) { 427 if (fatent->entry < sbi->max_cluster) 428 return 1; 429 } 430 return 0; 431 } 432 433 static inline int fat_ent_read_block(struct super_block *sb, 434 struct fat_entry *fatent) 435 { 436 const struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops; 437 sector_t blocknr; 438 int offset; 439 440 fatent_brelse(fatent); 441 ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr); 442 return ops->ent_bread(sb, fatent, offset, blocknr); 443 } 444 445 static void fat_collect_bhs(struct buffer_head **bhs, int *nr_bhs, 446 struct fat_entry *fatent) 447 { 448 int n, i; 449 450 for (n = 0; n < fatent->nr_bhs; n++) { 451 for (i = 0; i < *nr_bhs; i++) { 452 if (fatent->bhs[n] == bhs[i]) 453 break; 454 } 455 if (i == *nr_bhs) { 456 get_bh(fatent->bhs[n]); 457 bhs[i] = fatent->bhs[n]; 458 (*nr_bhs)++; 459 } 460 } 461 } 462 463 int fat_alloc_clusters(struct inode *inode, int *cluster, int nr_cluster) 464 { 465 struct super_block *sb = inode->i_sb; 466 struct msdos_sb_info *sbi = MSDOS_SB(sb); 467 const struct fatent_operations *ops = sbi->fatent_ops; 468 struct fat_entry fatent, prev_ent; 469 struct buffer_head *bhs[MAX_BUF_PER_PAGE]; 470 int i, count, err, nr_bhs, idx_clus; 471 472 BUG_ON(nr_cluster > (MAX_BUF_PER_PAGE / 2)); /* fixed limit */ 473 474 lock_fat(sbi); 475 if (sbi->free_clusters != -1 && sbi->free_clus_valid && 476 sbi->free_clusters < nr_cluster) { 477 unlock_fat(sbi); 478 return -ENOSPC; 479 } 480 481 err = nr_bhs = idx_clus = 0; 482 count = FAT_START_ENT; 483 fatent_init(&prev_ent); 484 fatent_init(&fatent); 485 fatent_set_entry(&fatent, sbi->prev_free + 1); 486 while (count < sbi->max_cluster) { 487 if (fatent.entry >= sbi->max_cluster) 488 fatent.entry = FAT_START_ENT; 489 fatent_set_entry(&fatent, fatent.entry); 490 err = fat_ent_read_block(sb, &fatent); 491 if (err) 492 goto out; 493 494 /* Find the free entries in a block */ 495 do { 496 if (ops->ent_get(&fatent) == FAT_ENT_FREE) { 497 int entry = fatent.entry; 498 499 /* make the cluster chain */ 500 ops->ent_put(&fatent, FAT_ENT_EOF); 501 if (prev_ent.nr_bhs) 502 ops->ent_put(&prev_ent, entry); 503 504 fat_collect_bhs(bhs, &nr_bhs, &fatent); 505 506 sbi->prev_free = entry; 507 if (sbi->free_clusters != -1) 508 sbi->free_clusters--; 509 510 cluster[idx_clus] = entry; 511 idx_clus++; 512 if (idx_clus == nr_cluster) 513 goto out; 514 515 /* 516 * fat_collect_bhs() gets ref-count of bhs, 517 * so we can still use the prev_ent. 518 */ 519 prev_ent = fatent; 520 } 521 count++; 522 if (count == sbi->max_cluster) 523 break; 524 } while (fat_ent_next(sbi, &fatent)); 525 } 526 527 /* Couldn't allocate the free entries */ 528 sbi->free_clusters = 0; 529 sbi->free_clus_valid = 1; 530 err = -ENOSPC; 531 532 out: 533 unlock_fat(sbi); 534 mark_fsinfo_dirty(sb); 535 fatent_brelse(&fatent); 536 if (!err) { 537 if (inode_needs_sync(inode)) 538 err = fat_sync_bhs(bhs, nr_bhs); 539 if (!err) 540 err = fat_mirror_bhs(sb, bhs, nr_bhs); 541 } 542 for (i = 0; i < nr_bhs; i++) 543 brelse(bhs[i]); 544 545 if (err && idx_clus) 546 fat_free_clusters(inode, cluster[0]); 547 548 return err; 549 } 550 551 int fat_free_clusters(struct inode *inode, int cluster) 552 { 553 struct super_block *sb = inode->i_sb; 554 struct msdos_sb_info *sbi = MSDOS_SB(sb); 555 const struct fatent_operations *ops = sbi->fatent_ops; 556 struct fat_entry fatent; 557 struct buffer_head *bhs[MAX_BUF_PER_PAGE]; 558 int i, err, nr_bhs; 559 int first_cl = cluster, dirty_fsinfo = 0; 560 561 nr_bhs = 0; 562 fatent_init(&fatent); 563 lock_fat(sbi); 564 do { 565 cluster = fat_ent_read(inode, &fatent, cluster); 566 if (cluster < 0) { 567 err = cluster; 568 goto error; 569 } else if (cluster == FAT_ENT_FREE) { 570 fat_fs_error(sb, "%s: deleting FAT entry beyond EOF", 571 __func__); 572 err = -EIO; 573 goto error; 574 } 575 576 if (sbi->options.discard) { 577 /* 578 * Issue discard for the sectors we no longer 579 * care about, batching contiguous clusters 580 * into one request 581 */ 582 if (cluster != fatent.entry + 1) { 583 int nr_clus = fatent.entry - first_cl + 1; 584 585 sb_issue_discard(sb, 586 fat_clus_to_blknr(sbi, first_cl), 587 nr_clus * sbi->sec_per_clus, 588 GFP_NOFS, 0); 589 590 first_cl = cluster; 591 } 592 } 593 594 ops->ent_put(&fatent, FAT_ENT_FREE); 595 if (sbi->free_clusters != -1) { 596 sbi->free_clusters++; 597 dirty_fsinfo = 1; 598 } 599 600 if (nr_bhs + fatent.nr_bhs > MAX_BUF_PER_PAGE) { 601 if (sb->s_flags & SB_SYNCHRONOUS) { 602 err = fat_sync_bhs(bhs, nr_bhs); 603 if (err) 604 goto error; 605 } 606 err = fat_mirror_bhs(sb, bhs, nr_bhs); 607 if (err) 608 goto error; 609 for (i = 0; i < nr_bhs; i++) 610 brelse(bhs[i]); 611 nr_bhs = 0; 612 } 613 fat_collect_bhs(bhs, &nr_bhs, &fatent); 614 } while (cluster != FAT_ENT_EOF); 615 616 if (sb->s_flags & SB_SYNCHRONOUS) { 617 err = fat_sync_bhs(bhs, nr_bhs); 618 if (err) 619 goto error; 620 } 621 err = fat_mirror_bhs(sb, bhs, nr_bhs); 622 error: 623 fatent_brelse(&fatent); 624 for (i = 0; i < nr_bhs; i++) 625 brelse(bhs[i]); 626 unlock_fat(sbi); 627 if (dirty_fsinfo) 628 mark_fsinfo_dirty(sb); 629 630 return err; 631 } 632 EXPORT_SYMBOL_GPL(fat_free_clusters); 633 634 /* 128kb is the whole sectors for FAT12 and FAT16 */ 635 #define FAT_READA_SIZE (128 * 1024) 636 637 static void fat_ent_reada(struct super_block *sb, struct fat_entry *fatent, 638 unsigned long reada_blocks) 639 { 640 const struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops; 641 sector_t blocknr; 642 int i, offset; 643 644 ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr); 645 646 for (i = 0; i < reada_blocks; i++) 647 sb_breadahead(sb, blocknr + i); 648 } 649 650 int fat_count_free_clusters(struct super_block *sb) 651 { 652 struct msdos_sb_info *sbi = MSDOS_SB(sb); 653 const struct fatent_operations *ops = sbi->fatent_ops; 654 struct fat_entry fatent; 655 unsigned long reada_blocks, reada_mask, cur_block; 656 int err = 0, free; 657 658 lock_fat(sbi); 659 if (sbi->free_clusters != -1 && sbi->free_clus_valid) 660 goto out; 661 662 reada_blocks = FAT_READA_SIZE >> sb->s_blocksize_bits; 663 reada_mask = reada_blocks - 1; 664 cur_block = 0; 665 666 free = 0; 667 fatent_init(&fatent); 668 fatent_set_entry(&fatent, FAT_START_ENT); 669 while (fatent.entry < sbi->max_cluster) { 670 /* readahead of fat blocks */ 671 if ((cur_block & reada_mask) == 0) { 672 unsigned long rest = sbi->fat_length - cur_block; 673 fat_ent_reada(sb, &fatent, min(reada_blocks, rest)); 674 } 675 cur_block++; 676 677 err = fat_ent_read_block(sb, &fatent); 678 if (err) 679 goto out; 680 681 do { 682 if (ops->ent_get(&fatent) == FAT_ENT_FREE) 683 free++; 684 } while (fat_ent_next(sbi, &fatent)); 685 cond_resched(); 686 } 687 sbi->free_clusters = free; 688 sbi->free_clus_valid = 1; 689 mark_fsinfo_dirty(sb); 690 fatent_brelse(&fatent); 691 out: 692 unlock_fat(sbi); 693 return err; 694 } 695 696 static int fat_trim_clusters(struct super_block *sb, u32 clus, u32 nr_clus) 697 { 698 struct msdos_sb_info *sbi = MSDOS_SB(sb); 699 return sb_issue_discard(sb, fat_clus_to_blknr(sbi, clus), 700 nr_clus * sbi->sec_per_clus, GFP_NOFS, 0); 701 } 702 703 int fat_trim_fs(struct inode *inode, struct fstrim_range *range) 704 { 705 struct super_block *sb = inode->i_sb; 706 struct msdos_sb_info *sbi = MSDOS_SB(sb); 707 const struct fatent_operations *ops = sbi->fatent_ops; 708 struct fat_entry fatent; 709 u64 ent_start, ent_end, minlen, trimmed = 0; 710 u32 free = 0; 711 unsigned long reada_blocks, reada_mask, cur_block = 0; 712 int err = 0; 713 714 /* 715 * FAT data is organized as clusters, trim at the granulary of cluster. 716 * 717 * fstrim_range is in byte, convert vaules to cluster index. 718 * Treat sectors before data region as all used, not to trim them. 719 */ 720 ent_start = max_t(u64, range->start>>sbi->cluster_bits, FAT_START_ENT); 721 ent_end = ent_start + (range->len >> sbi->cluster_bits) - 1; 722 minlen = range->minlen >> sbi->cluster_bits; 723 724 if (ent_start >= sbi->max_cluster || range->len < sbi->cluster_size) 725 return -EINVAL; 726 if (ent_end >= sbi->max_cluster) 727 ent_end = sbi->max_cluster - 1; 728 729 reada_blocks = FAT_READA_SIZE >> sb->s_blocksize_bits; 730 reada_mask = reada_blocks - 1; 731 732 fatent_init(&fatent); 733 lock_fat(sbi); 734 fatent_set_entry(&fatent, ent_start); 735 while (fatent.entry <= ent_end) { 736 /* readahead of fat blocks */ 737 if ((cur_block & reada_mask) == 0) { 738 unsigned long rest = sbi->fat_length - cur_block; 739 fat_ent_reada(sb, &fatent, min(reada_blocks, rest)); 740 } 741 cur_block++; 742 743 err = fat_ent_read_block(sb, &fatent); 744 if (err) 745 goto error; 746 do { 747 if (ops->ent_get(&fatent) == FAT_ENT_FREE) { 748 free++; 749 } else if (free) { 750 if (free >= minlen) { 751 u32 clus = fatent.entry - free; 752 753 err = fat_trim_clusters(sb, clus, free); 754 if (err && err != -EOPNOTSUPP) 755 goto error; 756 if (!err) 757 trimmed += free; 758 err = 0; 759 } 760 free = 0; 761 } 762 } while (fat_ent_next(sbi, &fatent) && fatent.entry <= ent_end); 763 764 if (fatal_signal_pending(current)) { 765 err = -ERESTARTSYS; 766 goto error; 767 } 768 769 if (need_resched()) { 770 fatent_brelse(&fatent); 771 unlock_fat(sbi); 772 cond_resched(); 773 lock_fat(sbi); 774 } 775 } 776 /* handle scenario when tail entries are all free */ 777 if (free && free >= minlen) { 778 u32 clus = fatent.entry - free; 779 780 err = fat_trim_clusters(sb, clus, free); 781 if (err && err != -EOPNOTSUPP) 782 goto error; 783 if (!err) 784 trimmed += free; 785 err = 0; 786 } 787 788 error: 789 fatent_brelse(&fatent); 790 unlock_fat(sbi); 791 792 range->len = trimmed << sbi->cluster_bits; 793 794 return err; 795 } 796