1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2004, OGAWA Hirofumi 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 if (is_fat32(sbi)) { 294 sbi->fatent_shift = 2; 295 sbi->fatent_ops = &fat32_ops; 296 } else if (is_fat16(sbi)) { 297 sbi->fatent_shift = 1; 298 sbi->fatent_ops = &fat16_ops; 299 } else if (is_fat12(sbi)) { 300 sbi->fatent_shift = -1; 301 sbi->fatent_ops = &fat12_ops; 302 } else { 303 fat_fs_error(sb, "invalid FAT variant, %u bits", sbi->fat_bits); 304 } 305 } 306 307 static void mark_fsinfo_dirty(struct super_block *sb) 308 { 309 struct msdos_sb_info *sbi = MSDOS_SB(sb); 310 311 if (sb_rdonly(sb) || !is_fat32(sbi)) 312 return; 313 314 __mark_inode_dirty(sbi->fsinfo_inode, I_DIRTY_SYNC); 315 } 316 317 static inline int fat_ent_update_ptr(struct super_block *sb, 318 struct fat_entry *fatent, 319 int offset, sector_t blocknr) 320 { 321 struct msdos_sb_info *sbi = MSDOS_SB(sb); 322 const struct fatent_operations *ops = sbi->fatent_ops; 323 struct buffer_head **bhs = fatent->bhs; 324 325 /* Is this fatent's blocks including this entry? */ 326 if (!fatent->nr_bhs || bhs[0]->b_blocknr != blocknr) 327 return 0; 328 if (is_fat12(sbi)) { 329 if ((offset + 1) < sb->s_blocksize) { 330 /* This entry is on bhs[0]. */ 331 if (fatent->nr_bhs == 2) { 332 brelse(bhs[1]); 333 fatent->nr_bhs = 1; 334 } 335 } else { 336 /* This entry needs the next block. */ 337 if (fatent->nr_bhs != 2) 338 return 0; 339 if (bhs[1]->b_blocknr != (blocknr + 1)) 340 return 0; 341 } 342 } 343 ops->ent_set_ptr(fatent, offset); 344 return 1; 345 } 346 347 int fat_ent_read(struct inode *inode, struct fat_entry *fatent, int entry) 348 { 349 struct super_block *sb = inode->i_sb; 350 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb); 351 const struct fatent_operations *ops = sbi->fatent_ops; 352 int err, offset; 353 sector_t blocknr; 354 355 if (!fat_valid_entry(sbi, entry)) { 356 fatent_brelse(fatent); 357 fat_fs_error(sb, "invalid access to FAT (entry 0x%08x)", entry); 358 return -EIO; 359 } 360 361 fatent_set_entry(fatent, entry); 362 ops->ent_blocknr(sb, entry, &offset, &blocknr); 363 364 if (!fat_ent_update_ptr(sb, fatent, offset, blocknr)) { 365 fatent_brelse(fatent); 366 err = ops->ent_bread(sb, fatent, offset, blocknr); 367 if (err) 368 return err; 369 } 370 return ops->ent_get(fatent); 371 } 372 373 /* FIXME: We can write the blocks as more big chunk. */ 374 static int fat_mirror_bhs(struct super_block *sb, struct buffer_head **bhs, 375 int nr_bhs) 376 { 377 struct msdos_sb_info *sbi = MSDOS_SB(sb); 378 struct buffer_head *c_bh; 379 int err, n, copy; 380 381 err = 0; 382 for (copy = 1; copy < sbi->fats; copy++) { 383 sector_t backup_fat = sbi->fat_length * copy; 384 385 for (n = 0; n < nr_bhs; n++) { 386 c_bh = sb_getblk(sb, backup_fat + bhs[n]->b_blocknr); 387 if (!c_bh) { 388 err = -ENOMEM; 389 goto error; 390 } 391 /* Avoid race with userspace read via bdev */ 392 lock_buffer(c_bh); 393 memcpy(c_bh->b_data, bhs[n]->b_data, sb->s_blocksize); 394 set_buffer_uptodate(c_bh); 395 unlock_buffer(c_bh); 396 mark_buffer_dirty_inode(c_bh, sbi->fat_inode); 397 if (sb->s_flags & SB_SYNCHRONOUS) 398 err = sync_dirty_buffer(c_bh); 399 brelse(c_bh); 400 if (err) 401 goto error; 402 } 403 } 404 error: 405 return err; 406 } 407 408 int fat_ent_write(struct inode *inode, struct fat_entry *fatent, 409 int new, int wait) 410 { 411 struct super_block *sb = inode->i_sb; 412 const struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops; 413 int err; 414 415 ops->ent_put(fatent, new); 416 if (wait) { 417 err = fat_sync_bhs(fatent->bhs, fatent->nr_bhs); 418 if (err) 419 return err; 420 } 421 return fat_mirror_bhs(sb, fatent->bhs, fatent->nr_bhs); 422 } 423 424 static inline int fat_ent_next(struct msdos_sb_info *sbi, 425 struct fat_entry *fatent) 426 { 427 if (sbi->fatent_ops->ent_next(fatent)) { 428 if (fatent->entry < sbi->max_cluster) 429 return 1; 430 } 431 return 0; 432 } 433 434 static inline int fat_ent_read_block(struct super_block *sb, 435 struct fat_entry *fatent) 436 { 437 const struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops; 438 sector_t blocknr; 439 int offset; 440 441 fatent_brelse(fatent); 442 ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr); 443 return ops->ent_bread(sb, fatent, offset, blocknr); 444 } 445 446 static void fat_collect_bhs(struct buffer_head **bhs, int *nr_bhs, 447 struct fat_entry *fatent) 448 { 449 int n, i; 450 451 for (n = 0; n < fatent->nr_bhs; n++) { 452 for (i = 0; i < *nr_bhs; i++) { 453 if (fatent->bhs[n] == bhs[i]) 454 break; 455 } 456 if (i == *nr_bhs) { 457 get_bh(fatent->bhs[n]); 458 bhs[i] = fatent->bhs[n]; 459 (*nr_bhs)++; 460 } 461 } 462 } 463 464 int fat_alloc_clusters(struct inode *inode, int *cluster, int nr_cluster) 465 { 466 struct super_block *sb = inode->i_sb; 467 struct msdos_sb_info *sbi = MSDOS_SB(sb); 468 const struct fatent_operations *ops = sbi->fatent_ops; 469 struct fat_entry fatent, prev_ent; 470 struct buffer_head *bhs[MAX_BUF_PER_PAGE]; 471 int i, count, err, nr_bhs, idx_clus; 472 473 BUG_ON(nr_cluster > (MAX_BUF_PER_PAGE / 2)); /* fixed limit */ 474 475 lock_fat(sbi); 476 if (sbi->free_clusters != -1 && sbi->free_clus_valid && 477 sbi->free_clusters < nr_cluster) { 478 unlock_fat(sbi); 479 return -ENOSPC; 480 } 481 482 err = nr_bhs = idx_clus = 0; 483 count = FAT_START_ENT; 484 fatent_init(&prev_ent); 485 fatent_init(&fatent); 486 fatent_set_entry(&fatent, sbi->prev_free + 1); 487 while (count < sbi->max_cluster) { 488 if (fatent.entry >= sbi->max_cluster) 489 fatent.entry = FAT_START_ENT; 490 fatent_set_entry(&fatent, fatent.entry); 491 err = fat_ent_read_block(sb, &fatent); 492 if (err) 493 goto out; 494 495 /* Find the free entries in a block */ 496 do { 497 if (ops->ent_get(&fatent) == FAT_ENT_FREE) { 498 int entry = fatent.entry; 499 500 /* make the cluster chain */ 501 ops->ent_put(&fatent, FAT_ENT_EOF); 502 if (prev_ent.nr_bhs) 503 ops->ent_put(&prev_ent, entry); 504 505 fat_collect_bhs(bhs, &nr_bhs, &fatent); 506 507 sbi->prev_free = entry; 508 if (sbi->free_clusters != -1) 509 sbi->free_clusters--; 510 511 cluster[idx_clus] = entry; 512 idx_clus++; 513 if (idx_clus == nr_cluster) 514 goto out; 515 516 /* 517 * fat_collect_bhs() gets ref-count of bhs, 518 * so we can still use the prev_ent. 519 */ 520 prev_ent = fatent; 521 } 522 count++; 523 if (count == sbi->max_cluster) 524 break; 525 } while (fat_ent_next(sbi, &fatent)); 526 } 527 528 /* Couldn't allocate the free entries */ 529 sbi->free_clusters = 0; 530 sbi->free_clus_valid = 1; 531 err = -ENOSPC; 532 533 out: 534 unlock_fat(sbi); 535 mark_fsinfo_dirty(sb); 536 fatent_brelse(&fatent); 537 if (!err) { 538 if (inode_needs_sync(inode)) 539 err = fat_sync_bhs(bhs, nr_bhs); 540 if (!err) 541 err = fat_mirror_bhs(sb, bhs, nr_bhs); 542 } 543 for (i = 0; i < nr_bhs; i++) 544 brelse(bhs[i]); 545 546 if (err && idx_clus) 547 fat_free_clusters(inode, cluster[0]); 548 549 return err; 550 } 551 552 int fat_free_clusters(struct inode *inode, int cluster) 553 { 554 struct super_block *sb = inode->i_sb; 555 struct msdos_sb_info *sbi = MSDOS_SB(sb); 556 const struct fatent_operations *ops = sbi->fatent_ops; 557 struct fat_entry fatent; 558 struct buffer_head *bhs[MAX_BUF_PER_PAGE]; 559 int i, err, nr_bhs; 560 int first_cl = cluster, dirty_fsinfo = 0; 561 562 nr_bhs = 0; 563 fatent_init(&fatent); 564 lock_fat(sbi); 565 do { 566 cluster = fat_ent_read(inode, &fatent, cluster); 567 if (cluster < 0) { 568 err = cluster; 569 goto error; 570 } else if (cluster == FAT_ENT_FREE) { 571 fat_fs_error(sb, "%s: deleting FAT entry beyond EOF", 572 __func__); 573 err = -EIO; 574 goto error; 575 } 576 577 if (sbi->options.discard) { 578 /* 579 * Issue discard for the sectors we no longer 580 * care about, batching contiguous clusters 581 * into one request 582 */ 583 if (cluster != fatent.entry + 1) { 584 int nr_clus = fatent.entry - first_cl + 1; 585 586 sb_issue_discard(sb, 587 fat_clus_to_blknr(sbi, first_cl), 588 nr_clus * sbi->sec_per_clus, 589 GFP_NOFS, 0); 590 591 first_cl = cluster; 592 } 593 } 594 595 ops->ent_put(&fatent, FAT_ENT_FREE); 596 if (sbi->free_clusters != -1) { 597 sbi->free_clusters++; 598 dirty_fsinfo = 1; 599 } 600 601 if (nr_bhs + fatent.nr_bhs > MAX_BUF_PER_PAGE) { 602 if (sb->s_flags & SB_SYNCHRONOUS) { 603 err = fat_sync_bhs(bhs, nr_bhs); 604 if (err) 605 goto error; 606 } 607 err = fat_mirror_bhs(sb, bhs, nr_bhs); 608 if (err) 609 goto error; 610 for (i = 0; i < nr_bhs; i++) 611 brelse(bhs[i]); 612 nr_bhs = 0; 613 } 614 fat_collect_bhs(bhs, &nr_bhs, &fatent); 615 } while (cluster != FAT_ENT_EOF); 616 617 if (sb->s_flags & SB_SYNCHRONOUS) { 618 err = fat_sync_bhs(bhs, nr_bhs); 619 if (err) 620 goto error; 621 } 622 err = fat_mirror_bhs(sb, bhs, nr_bhs); 623 error: 624 fatent_brelse(&fatent); 625 for (i = 0; i < nr_bhs; i++) 626 brelse(bhs[i]); 627 unlock_fat(sbi); 628 if (dirty_fsinfo) 629 mark_fsinfo_dirty(sb); 630 631 return err; 632 } 633 EXPORT_SYMBOL_GPL(fat_free_clusters); 634 635 struct fatent_ra { 636 sector_t cur; 637 sector_t limit; 638 639 unsigned int ra_blocks; 640 sector_t ra_advance; 641 sector_t ra_next; 642 sector_t ra_limit; 643 }; 644 645 static void fat_ra_init(struct super_block *sb, struct fatent_ra *ra, 646 struct fat_entry *fatent, int ent_limit) 647 { 648 struct msdos_sb_info *sbi = MSDOS_SB(sb); 649 const struct fatent_operations *ops = sbi->fatent_ops; 650 sector_t blocknr, block_end; 651 int offset; 652 /* 653 * This is the sequential read, so ra_pages * 2 (but try to 654 * align the optimal hardware IO size). 655 * [BTW, 128kb covers the whole sectors for FAT12 and FAT16] 656 */ 657 unsigned long ra_pages = sb->s_bdi->ra_pages; 658 unsigned int reada_blocks; 659 660 if (fatent->entry >= ent_limit) 661 return; 662 663 if (ra_pages > sb->s_bdi->io_pages) 664 ra_pages = rounddown(ra_pages, sb->s_bdi->io_pages); 665 reada_blocks = ra_pages << (PAGE_SHIFT - sb->s_blocksize_bits + 1); 666 667 /* Initialize the range for sequential read */ 668 ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr); 669 ops->ent_blocknr(sb, ent_limit - 1, &offset, &block_end); 670 ra->cur = 0; 671 ra->limit = (block_end + 1) - blocknr; 672 673 /* Advancing the window at half size */ 674 ra->ra_blocks = reada_blocks >> 1; 675 ra->ra_advance = ra->cur; 676 ra->ra_next = ra->cur; 677 ra->ra_limit = ra->cur + min_t(sector_t, reada_blocks, ra->limit); 678 } 679 680 /* Assuming to be called before reading a new block (increments ->cur). */ 681 static void fat_ent_reada(struct super_block *sb, struct fatent_ra *ra, 682 struct fat_entry *fatent) 683 { 684 if (ra->ra_next >= ra->ra_limit) 685 return; 686 687 if (ra->cur >= ra->ra_advance) { 688 struct msdos_sb_info *sbi = MSDOS_SB(sb); 689 const struct fatent_operations *ops = sbi->fatent_ops; 690 struct blk_plug plug; 691 sector_t blocknr, diff; 692 int offset; 693 694 ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr); 695 696 diff = blocknr - ra->cur; 697 blk_start_plug(&plug); 698 /* 699 * FIXME: we would want to directly use the bio with 700 * pages to reduce the number of segments. 701 */ 702 for (; ra->ra_next < ra->ra_limit; ra->ra_next++) 703 sb_breadahead(sb, ra->ra_next + diff); 704 blk_finish_plug(&plug); 705 706 /* Advance the readahead window */ 707 ra->ra_advance += ra->ra_blocks; 708 ra->ra_limit += min_t(sector_t, 709 ra->ra_blocks, ra->limit - ra->ra_limit); 710 } 711 ra->cur++; 712 } 713 714 int fat_count_free_clusters(struct super_block *sb) 715 { 716 struct msdos_sb_info *sbi = MSDOS_SB(sb); 717 const struct fatent_operations *ops = sbi->fatent_ops; 718 struct fat_entry fatent; 719 struct fatent_ra fatent_ra; 720 int err = 0, free; 721 722 lock_fat(sbi); 723 if (sbi->free_clusters != -1 && sbi->free_clus_valid) 724 goto out; 725 726 free = 0; 727 fatent_init(&fatent); 728 fatent_set_entry(&fatent, FAT_START_ENT); 729 fat_ra_init(sb, &fatent_ra, &fatent, sbi->max_cluster); 730 while (fatent.entry < sbi->max_cluster) { 731 /* readahead of fat blocks */ 732 fat_ent_reada(sb, &fatent_ra, &fatent); 733 734 err = fat_ent_read_block(sb, &fatent); 735 if (err) 736 goto out; 737 738 do { 739 if (ops->ent_get(&fatent) == FAT_ENT_FREE) 740 free++; 741 } while (fat_ent_next(sbi, &fatent)); 742 cond_resched(); 743 } 744 sbi->free_clusters = free; 745 sbi->free_clus_valid = 1; 746 mark_fsinfo_dirty(sb); 747 fatent_brelse(&fatent); 748 out: 749 unlock_fat(sbi); 750 return err; 751 } 752 753 static int fat_trim_clusters(struct super_block *sb, u32 clus, u32 nr_clus) 754 { 755 struct msdos_sb_info *sbi = MSDOS_SB(sb); 756 return sb_issue_discard(sb, fat_clus_to_blknr(sbi, clus), 757 nr_clus * sbi->sec_per_clus, GFP_NOFS, 0); 758 } 759 760 int fat_trim_fs(struct inode *inode, struct fstrim_range *range) 761 { 762 struct super_block *sb = inode->i_sb; 763 struct msdos_sb_info *sbi = MSDOS_SB(sb); 764 const struct fatent_operations *ops = sbi->fatent_ops; 765 struct fat_entry fatent; 766 struct fatent_ra fatent_ra; 767 u64 ent_start, ent_end, minlen, trimmed = 0; 768 u32 free = 0; 769 int err = 0; 770 771 /* 772 * FAT data is organized as clusters, trim at the granulary of cluster. 773 * 774 * fstrim_range is in byte, convert vaules to cluster index. 775 * Treat sectors before data region as all used, not to trim them. 776 */ 777 ent_start = max_t(u64, range->start>>sbi->cluster_bits, FAT_START_ENT); 778 ent_end = ent_start + (range->len >> sbi->cluster_bits) - 1; 779 minlen = range->minlen >> sbi->cluster_bits; 780 781 if (ent_start >= sbi->max_cluster || range->len < sbi->cluster_size) 782 return -EINVAL; 783 if (ent_end >= sbi->max_cluster) 784 ent_end = sbi->max_cluster - 1; 785 786 fatent_init(&fatent); 787 lock_fat(sbi); 788 fatent_set_entry(&fatent, ent_start); 789 fat_ra_init(sb, &fatent_ra, &fatent, ent_end + 1); 790 while (fatent.entry <= ent_end) { 791 /* readahead of fat blocks */ 792 fat_ent_reada(sb, &fatent_ra, &fatent); 793 794 err = fat_ent_read_block(sb, &fatent); 795 if (err) 796 goto error; 797 do { 798 if (ops->ent_get(&fatent) == FAT_ENT_FREE) { 799 free++; 800 } else if (free) { 801 if (free >= minlen) { 802 u32 clus = fatent.entry - free; 803 804 err = fat_trim_clusters(sb, clus, free); 805 if (err && err != -EOPNOTSUPP) 806 goto error; 807 if (!err) 808 trimmed += free; 809 err = 0; 810 } 811 free = 0; 812 } 813 } while (fat_ent_next(sbi, &fatent) && fatent.entry <= ent_end); 814 815 if (fatal_signal_pending(current)) { 816 err = -ERESTARTSYS; 817 goto error; 818 } 819 820 if (need_resched()) { 821 fatent_brelse(&fatent); 822 unlock_fat(sbi); 823 cond_resched(); 824 lock_fat(sbi); 825 } 826 } 827 /* handle scenario when tail entries are all free */ 828 if (free && free >= minlen) { 829 u32 clus = fatent.entry - free; 830 831 err = fat_trim_clusters(sb, clus, free); 832 if (err && err != -EOPNOTSUPP) 833 goto error; 834 if (!err) 835 trimmed += free; 836 err = 0; 837 } 838 839 error: 840 fatent_brelse(&fatent); 841 unlock_fat(sbi); 842 843 range->len = trimmed << sbi->cluster_bits; 844 845 return err; 846 } 847