1 /* 2 * linux/fs/ext2/dir.c 3 * 4 * Copyright (C) 1992, 1993, 1994, 1995 5 * Remy Card (card@masi.ibp.fr) 6 * Laboratoire MASI - Institut Blaise Pascal 7 * Universite Pierre et Marie Curie (Paris VI) 8 * 9 * from 10 * 11 * linux/fs/minix/dir.c 12 * 13 * Copyright (C) 1991, 1992 Linus Torvalds 14 * 15 * ext2 directory handling functions 16 * 17 * Big-endian to little-endian byte-swapping/bitmaps by 18 * David S. Miller (davem@caip.rutgers.edu), 1995 19 * 20 * All code that works with directory layout had been switched to pagecache 21 * and moved here. AV 22 */ 23 24 #include "ext2.h" 25 #include <linux/pagemap.h> 26 #include <linux/smp_lock.h> 27 28 typedef struct ext2_dir_entry_2 ext2_dirent; 29 30 /* 31 * ext2 uses block-sized chunks. Arguably, sector-sized ones would be 32 * more robust, but we have what we have 33 */ 34 static inline unsigned ext2_chunk_size(struct inode *inode) 35 { 36 return inode->i_sb->s_blocksize; 37 } 38 39 static inline void ext2_put_page(struct page *page) 40 { 41 kunmap(page); 42 page_cache_release(page); 43 } 44 45 static inline unsigned long dir_pages(struct inode *inode) 46 { 47 return (inode->i_size+PAGE_CACHE_SIZE-1)>>PAGE_CACHE_SHIFT; 48 } 49 50 /* 51 * Return the offset into page `page_nr' of the last valid 52 * byte in that page, plus one. 53 */ 54 static unsigned 55 ext2_last_byte(struct inode *inode, unsigned long page_nr) 56 { 57 unsigned last_byte = inode->i_size; 58 59 last_byte -= page_nr << PAGE_CACHE_SHIFT; 60 if (last_byte > PAGE_CACHE_SIZE) 61 last_byte = PAGE_CACHE_SIZE; 62 return last_byte; 63 } 64 65 static int ext2_commit_chunk(struct page *page, unsigned from, unsigned to) 66 { 67 struct inode *dir = page->mapping->host; 68 int err = 0; 69 dir->i_version++; 70 page->mapping->a_ops->commit_write(NULL, page, from, to); 71 if (IS_DIRSYNC(dir)) 72 err = write_one_page(page, 1); 73 else 74 unlock_page(page); 75 return err; 76 } 77 78 static void ext2_check_page(struct page *page) 79 { 80 struct inode *dir = page->mapping->host; 81 struct super_block *sb = dir->i_sb; 82 unsigned chunk_size = ext2_chunk_size(dir); 83 char *kaddr = page_address(page); 84 u32 max_inumber = le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count); 85 unsigned offs, rec_len; 86 unsigned limit = PAGE_CACHE_SIZE; 87 ext2_dirent *p; 88 char *error; 89 90 if ((dir->i_size >> PAGE_CACHE_SHIFT) == page->index) { 91 limit = dir->i_size & ~PAGE_CACHE_MASK; 92 if (limit & (chunk_size - 1)) 93 goto Ebadsize; 94 if (!limit) 95 goto out; 96 } 97 for (offs = 0; offs <= limit - EXT2_DIR_REC_LEN(1); offs += rec_len) { 98 p = (ext2_dirent *)(kaddr + offs); 99 rec_len = le16_to_cpu(p->rec_len); 100 101 if (rec_len < EXT2_DIR_REC_LEN(1)) 102 goto Eshort; 103 if (rec_len & 3) 104 goto Ealign; 105 if (rec_len < EXT2_DIR_REC_LEN(p->name_len)) 106 goto Enamelen; 107 if (((offs + rec_len - 1) ^ offs) & ~(chunk_size-1)) 108 goto Espan; 109 if (le32_to_cpu(p->inode) > max_inumber) 110 goto Einumber; 111 } 112 if (offs != limit) 113 goto Eend; 114 out: 115 SetPageChecked(page); 116 return; 117 118 /* Too bad, we had an error */ 119 120 Ebadsize: 121 ext2_error(sb, "ext2_check_page", 122 "size of directory #%lu is not a multiple of chunk size", 123 dir->i_ino 124 ); 125 goto fail; 126 Eshort: 127 error = "rec_len is smaller than minimal"; 128 goto bad_entry; 129 Ealign: 130 error = "unaligned directory entry"; 131 goto bad_entry; 132 Enamelen: 133 error = "rec_len is too small for name_len"; 134 goto bad_entry; 135 Espan: 136 error = "directory entry across blocks"; 137 goto bad_entry; 138 Einumber: 139 error = "inode out of bounds"; 140 bad_entry: 141 ext2_error (sb, "ext2_check_page", "bad entry in directory #%lu: %s - " 142 "offset=%lu, inode=%lu, rec_len=%d, name_len=%d", 143 dir->i_ino, error, (page->index<<PAGE_CACHE_SHIFT)+offs, 144 (unsigned long) le32_to_cpu(p->inode), 145 rec_len, p->name_len); 146 goto fail; 147 Eend: 148 p = (ext2_dirent *)(kaddr + offs); 149 ext2_error (sb, "ext2_check_page", 150 "entry in directory #%lu spans the page boundary" 151 "offset=%lu, inode=%lu", 152 dir->i_ino, (page->index<<PAGE_CACHE_SHIFT)+offs, 153 (unsigned long) le32_to_cpu(p->inode)); 154 fail: 155 SetPageChecked(page); 156 SetPageError(page); 157 } 158 159 static struct page * ext2_get_page(struct inode *dir, unsigned long n) 160 { 161 struct address_space *mapping = dir->i_mapping; 162 struct page *page = read_mapping_page(mapping, n, NULL); 163 if (!IS_ERR(page)) { 164 kmap(page); 165 if (!PageChecked(page)) 166 ext2_check_page(page); 167 if (PageError(page)) 168 goto fail; 169 } 170 return page; 171 172 fail: 173 ext2_put_page(page); 174 return ERR_PTR(-EIO); 175 } 176 177 /* 178 * NOTE! unlike strncmp, ext2_match returns 1 for success, 0 for failure. 179 * 180 * len <= EXT2_NAME_LEN and de != NULL are guaranteed by caller. 181 */ 182 static inline int ext2_match (int len, const char * const name, 183 struct ext2_dir_entry_2 * de) 184 { 185 if (len != de->name_len) 186 return 0; 187 if (!de->inode) 188 return 0; 189 return !memcmp(name, de->name, len); 190 } 191 192 /* 193 * p is at least 6 bytes before the end of page 194 */ 195 static inline ext2_dirent *ext2_next_entry(ext2_dirent *p) 196 { 197 return (ext2_dirent *)((char*)p + le16_to_cpu(p->rec_len)); 198 } 199 200 static inline unsigned 201 ext2_validate_entry(char *base, unsigned offset, unsigned mask) 202 { 203 ext2_dirent *de = (ext2_dirent*)(base + offset); 204 ext2_dirent *p = (ext2_dirent*)(base + (offset&mask)); 205 while ((char*)p < (char*)de) { 206 if (p->rec_len == 0) 207 break; 208 p = ext2_next_entry(p); 209 } 210 return (char *)p - base; 211 } 212 213 static unsigned char ext2_filetype_table[EXT2_FT_MAX] = { 214 [EXT2_FT_UNKNOWN] = DT_UNKNOWN, 215 [EXT2_FT_REG_FILE] = DT_REG, 216 [EXT2_FT_DIR] = DT_DIR, 217 [EXT2_FT_CHRDEV] = DT_CHR, 218 [EXT2_FT_BLKDEV] = DT_BLK, 219 [EXT2_FT_FIFO] = DT_FIFO, 220 [EXT2_FT_SOCK] = DT_SOCK, 221 [EXT2_FT_SYMLINK] = DT_LNK, 222 }; 223 224 #define S_SHIFT 12 225 static unsigned char ext2_type_by_mode[S_IFMT >> S_SHIFT] = { 226 [S_IFREG >> S_SHIFT] = EXT2_FT_REG_FILE, 227 [S_IFDIR >> S_SHIFT] = EXT2_FT_DIR, 228 [S_IFCHR >> S_SHIFT] = EXT2_FT_CHRDEV, 229 [S_IFBLK >> S_SHIFT] = EXT2_FT_BLKDEV, 230 [S_IFIFO >> S_SHIFT] = EXT2_FT_FIFO, 231 [S_IFSOCK >> S_SHIFT] = EXT2_FT_SOCK, 232 [S_IFLNK >> S_SHIFT] = EXT2_FT_SYMLINK, 233 }; 234 235 static inline void ext2_set_de_type(ext2_dirent *de, struct inode *inode) 236 { 237 mode_t mode = inode->i_mode; 238 if (EXT2_HAS_INCOMPAT_FEATURE(inode->i_sb, EXT2_FEATURE_INCOMPAT_FILETYPE)) 239 de->file_type = ext2_type_by_mode[(mode & S_IFMT)>>S_SHIFT]; 240 else 241 de->file_type = 0; 242 } 243 244 static int 245 ext2_readdir (struct file * filp, void * dirent, filldir_t filldir) 246 { 247 loff_t pos = filp->f_pos; 248 struct inode *inode = filp->f_path.dentry->d_inode; 249 struct super_block *sb = inode->i_sb; 250 unsigned int offset = pos & ~PAGE_CACHE_MASK; 251 unsigned long n = pos >> PAGE_CACHE_SHIFT; 252 unsigned long npages = dir_pages(inode); 253 unsigned chunk_mask = ~(ext2_chunk_size(inode)-1); 254 unsigned char *types = NULL; 255 int need_revalidate = filp->f_version != inode->i_version; 256 257 if (pos > inode->i_size - EXT2_DIR_REC_LEN(1)) 258 return 0; 259 260 if (EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_FILETYPE)) 261 types = ext2_filetype_table; 262 263 for ( ; n < npages; n++, offset = 0) { 264 char *kaddr, *limit; 265 ext2_dirent *de; 266 struct page *page = ext2_get_page(inode, n); 267 268 if (IS_ERR(page)) { 269 ext2_error(sb, __FUNCTION__, 270 "bad page in #%lu", 271 inode->i_ino); 272 filp->f_pos += PAGE_CACHE_SIZE - offset; 273 return -EIO; 274 } 275 kaddr = page_address(page); 276 if (unlikely(need_revalidate)) { 277 if (offset) { 278 offset = ext2_validate_entry(kaddr, offset, chunk_mask); 279 filp->f_pos = (n<<PAGE_CACHE_SHIFT) + offset; 280 } 281 filp->f_version = inode->i_version; 282 need_revalidate = 0; 283 } 284 de = (ext2_dirent *)(kaddr+offset); 285 limit = kaddr + ext2_last_byte(inode, n) - EXT2_DIR_REC_LEN(1); 286 for ( ;(char*)de <= limit; de = ext2_next_entry(de)) { 287 if (de->rec_len == 0) { 288 ext2_error(sb, __FUNCTION__, 289 "zero-length directory entry"); 290 ext2_put_page(page); 291 return -EIO; 292 } 293 if (de->inode) { 294 int over; 295 unsigned char d_type = DT_UNKNOWN; 296 297 if (types && de->file_type < EXT2_FT_MAX) 298 d_type = types[de->file_type]; 299 300 offset = (char *)de - kaddr; 301 over = filldir(dirent, de->name, de->name_len, 302 (n<<PAGE_CACHE_SHIFT) | offset, 303 le32_to_cpu(de->inode), d_type); 304 if (over) { 305 ext2_put_page(page); 306 return 0; 307 } 308 } 309 filp->f_pos += le16_to_cpu(de->rec_len); 310 } 311 ext2_put_page(page); 312 } 313 return 0; 314 } 315 316 /* 317 * ext2_find_entry() 318 * 319 * finds an entry in the specified directory with the wanted name. It 320 * returns the page in which the entry was found, and the entry itself 321 * (as a parameter - res_dir). Page is returned mapped and unlocked. 322 * Entry is guaranteed to be valid. 323 */ 324 struct ext2_dir_entry_2 * ext2_find_entry (struct inode * dir, 325 struct dentry *dentry, struct page ** res_page) 326 { 327 const char *name = dentry->d_name.name; 328 int namelen = dentry->d_name.len; 329 unsigned reclen = EXT2_DIR_REC_LEN(namelen); 330 unsigned long start, n; 331 unsigned long npages = dir_pages(dir); 332 struct page *page = NULL; 333 struct ext2_inode_info *ei = EXT2_I(dir); 334 ext2_dirent * de; 335 336 if (npages == 0) 337 goto out; 338 339 /* OFFSET_CACHE */ 340 *res_page = NULL; 341 342 start = ei->i_dir_start_lookup; 343 if (start >= npages) 344 start = 0; 345 n = start; 346 do { 347 char *kaddr; 348 page = ext2_get_page(dir, n); 349 if (!IS_ERR(page)) { 350 kaddr = page_address(page); 351 de = (ext2_dirent *) kaddr; 352 kaddr += ext2_last_byte(dir, n) - reclen; 353 while ((char *) de <= kaddr) { 354 if (de->rec_len == 0) { 355 ext2_error(dir->i_sb, __FUNCTION__, 356 "zero-length directory entry"); 357 ext2_put_page(page); 358 goto out; 359 } 360 if (ext2_match (namelen, name, de)) 361 goto found; 362 de = ext2_next_entry(de); 363 } 364 ext2_put_page(page); 365 } 366 if (++n >= npages) 367 n = 0; 368 /* next page is past the blocks we've got */ 369 if (unlikely(n > (dir->i_blocks >> (PAGE_CACHE_SHIFT - 9)))) { 370 ext2_error(dir->i_sb, __FUNCTION__, 371 "dir %lu size %lld exceeds block count %llu", 372 dir->i_ino, dir->i_size, 373 (unsigned long long)dir->i_blocks); 374 goto out; 375 } 376 } while (n != start); 377 out: 378 return NULL; 379 380 found: 381 *res_page = page; 382 ei->i_dir_start_lookup = n; 383 return de; 384 } 385 386 struct ext2_dir_entry_2 * ext2_dotdot (struct inode *dir, struct page **p) 387 { 388 struct page *page = ext2_get_page(dir, 0); 389 ext2_dirent *de = NULL; 390 391 if (!IS_ERR(page)) { 392 de = ext2_next_entry((ext2_dirent *) page_address(page)); 393 *p = page; 394 } 395 return de; 396 } 397 398 ino_t ext2_inode_by_name(struct inode * dir, struct dentry *dentry) 399 { 400 ino_t res = 0; 401 struct ext2_dir_entry_2 * de; 402 struct page *page; 403 404 de = ext2_find_entry (dir, dentry, &page); 405 if (de) { 406 res = le32_to_cpu(de->inode); 407 ext2_put_page(page); 408 } 409 return res; 410 } 411 412 /* Releases the page */ 413 void ext2_set_link(struct inode *dir, struct ext2_dir_entry_2 *de, 414 struct page *page, struct inode *inode) 415 { 416 unsigned from = (char *) de - (char *) page_address(page); 417 unsigned to = from + le16_to_cpu(de->rec_len); 418 int err; 419 420 lock_page(page); 421 err = page->mapping->a_ops->prepare_write(NULL, page, from, to); 422 BUG_ON(err); 423 de->inode = cpu_to_le32(inode->i_ino); 424 ext2_set_de_type (de, inode); 425 err = ext2_commit_chunk(page, from, to); 426 ext2_put_page(page); 427 dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC; 428 EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL; 429 mark_inode_dirty(dir); 430 } 431 432 /* 433 * Parent is locked. 434 */ 435 int ext2_add_link (struct dentry *dentry, struct inode *inode) 436 { 437 struct inode *dir = dentry->d_parent->d_inode; 438 const char *name = dentry->d_name.name; 439 int namelen = dentry->d_name.len; 440 unsigned chunk_size = ext2_chunk_size(dir); 441 unsigned reclen = EXT2_DIR_REC_LEN(namelen); 442 unsigned short rec_len, name_len; 443 struct page *page = NULL; 444 ext2_dirent * de; 445 unsigned long npages = dir_pages(dir); 446 unsigned long n; 447 char *kaddr; 448 unsigned from, to; 449 int err; 450 451 /* 452 * We take care of directory expansion in the same loop. 453 * This code plays outside i_size, so it locks the page 454 * to protect that region. 455 */ 456 for (n = 0; n <= npages; n++) { 457 char *dir_end; 458 459 page = ext2_get_page(dir, n); 460 err = PTR_ERR(page); 461 if (IS_ERR(page)) 462 goto out; 463 lock_page(page); 464 kaddr = page_address(page); 465 dir_end = kaddr + ext2_last_byte(dir, n); 466 de = (ext2_dirent *)kaddr; 467 kaddr += PAGE_CACHE_SIZE - reclen; 468 while ((char *)de <= kaddr) { 469 if ((char *)de == dir_end) { 470 /* We hit i_size */ 471 name_len = 0; 472 rec_len = chunk_size; 473 de->rec_len = cpu_to_le16(chunk_size); 474 de->inode = 0; 475 goto got_it; 476 } 477 if (de->rec_len == 0) { 478 ext2_error(dir->i_sb, __FUNCTION__, 479 "zero-length directory entry"); 480 err = -EIO; 481 goto out_unlock; 482 } 483 err = -EEXIST; 484 if (ext2_match (namelen, name, de)) 485 goto out_unlock; 486 name_len = EXT2_DIR_REC_LEN(de->name_len); 487 rec_len = le16_to_cpu(de->rec_len); 488 if (!de->inode && rec_len >= reclen) 489 goto got_it; 490 if (rec_len >= name_len + reclen) 491 goto got_it; 492 de = (ext2_dirent *) ((char *) de + rec_len); 493 } 494 unlock_page(page); 495 ext2_put_page(page); 496 } 497 BUG(); 498 return -EINVAL; 499 500 got_it: 501 from = (char*)de - (char*)page_address(page); 502 to = from + rec_len; 503 err = page->mapping->a_ops->prepare_write(NULL, page, from, to); 504 if (err) 505 goto out_unlock; 506 if (de->inode) { 507 ext2_dirent *de1 = (ext2_dirent *) ((char *) de + name_len); 508 de1->rec_len = cpu_to_le16(rec_len - name_len); 509 de->rec_len = cpu_to_le16(name_len); 510 de = de1; 511 } 512 de->name_len = namelen; 513 memcpy (de->name, name, namelen); 514 de->inode = cpu_to_le32(inode->i_ino); 515 ext2_set_de_type (de, inode); 516 err = ext2_commit_chunk(page, from, to); 517 dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC; 518 EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL; 519 mark_inode_dirty(dir); 520 /* OFFSET_CACHE */ 521 out_put: 522 ext2_put_page(page); 523 out: 524 return err; 525 out_unlock: 526 unlock_page(page); 527 goto out_put; 528 } 529 530 /* 531 * ext2_delete_entry deletes a directory entry by merging it with the 532 * previous entry. Page is up-to-date. Releases the page. 533 */ 534 int ext2_delete_entry (struct ext2_dir_entry_2 * dir, struct page * page ) 535 { 536 struct address_space *mapping = page->mapping; 537 struct inode *inode = mapping->host; 538 char *kaddr = page_address(page); 539 unsigned from = ((char*)dir - kaddr) & ~(ext2_chunk_size(inode)-1); 540 unsigned to = ((char*)dir - kaddr) + le16_to_cpu(dir->rec_len); 541 ext2_dirent * pde = NULL; 542 ext2_dirent * de = (ext2_dirent *) (kaddr + from); 543 int err; 544 545 while ((char*)de < (char*)dir) { 546 if (de->rec_len == 0) { 547 ext2_error(inode->i_sb, __FUNCTION__, 548 "zero-length directory entry"); 549 err = -EIO; 550 goto out; 551 } 552 pde = de; 553 de = ext2_next_entry(de); 554 } 555 if (pde) 556 from = (char*)pde - (char*)page_address(page); 557 lock_page(page); 558 err = mapping->a_ops->prepare_write(NULL, page, from, to); 559 BUG_ON(err); 560 if (pde) 561 pde->rec_len = cpu_to_le16(to-from); 562 dir->inode = 0; 563 err = ext2_commit_chunk(page, from, to); 564 inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC; 565 EXT2_I(inode)->i_flags &= ~EXT2_BTREE_FL; 566 mark_inode_dirty(inode); 567 out: 568 ext2_put_page(page); 569 return err; 570 } 571 572 /* 573 * Set the first fragment of directory. 574 */ 575 int ext2_make_empty(struct inode *inode, struct inode *parent) 576 { 577 struct address_space *mapping = inode->i_mapping; 578 struct page *page = grab_cache_page(mapping, 0); 579 unsigned chunk_size = ext2_chunk_size(inode); 580 struct ext2_dir_entry_2 * de; 581 int err; 582 void *kaddr; 583 584 if (!page) 585 return -ENOMEM; 586 err = mapping->a_ops->prepare_write(NULL, page, 0, chunk_size); 587 if (err) { 588 unlock_page(page); 589 goto fail; 590 } 591 kaddr = kmap_atomic(page, KM_USER0); 592 memset(kaddr, 0, chunk_size); 593 de = (struct ext2_dir_entry_2 *)kaddr; 594 de->name_len = 1; 595 de->rec_len = cpu_to_le16(EXT2_DIR_REC_LEN(1)); 596 memcpy (de->name, ".\0\0", 4); 597 de->inode = cpu_to_le32(inode->i_ino); 598 ext2_set_de_type (de, inode); 599 600 de = (struct ext2_dir_entry_2 *)(kaddr + EXT2_DIR_REC_LEN(1)); 601 de->name_len = 2; 602 de->rec_len = cpu_to_le16(chunk_size - EXT2_DIR_REC_LEN(1)); 603 de->inode = cpu_to_le32(parent->i_ino); 604 memcpy (de->name, "..\0", 4); 605 ext2_set_de_type (de, inode); 606 kunmap_atomic(kaddr, KM_USER0); 607 err = ext2_commit_chunk(page, 0, chunk_size); 608 fail: 609 page_cache_release(page); 610 return err; 611 } 612 613 /* 614 * routine to check that the specified directory is empty (for rmdir) 615 */ 616 int ext2_empty_dir (struct inode * inode) 617 { 618 struct page *page = NULL; 619 unsigned long i, npages = dir_pages(inode); 620 621 for (i = 0; i < npages; i++) { 622 char *kaddr; 623 ext2_dirent * de; 624 page = ext2_get_page(inode, i); 625 626 if (IS_ERR(page)) 627 continue; 628 629 kaddr = page_address(page); 630 de = (ext2_dirent *)kaddr; 631 kaddr += ext2_last_byte(inode, i) - EXT2_DIR_REC_LEN(1); 632 633 while ((char *)de <= kaddr) { 634 if (de->rec_len == 0) { 635 ext2_error(inode->i_sb, __FUNCTION__, 636 "zero-length directory entry"); 637 printk("kaddr=%p, de=%p\n", kaddr, de); 638 goto not_empty; 639 } 640 if (de->inode != 0) { 641 /* check for . and .. */ 642 if (de->name[0] != '.') 643 goto not_empty; 644 if (de->name_len > 2) 645 goto not_empty; 646 if (de->name_len < 2) { 647 if (de->inode != 648 cpu_to_le32(inode->i_ino)) 649 goto not_empty; 650 } else if (de->name[1] != '.') 651 goto not_empty; 652 } 653 de = ext2_next_entry(de); 654 } 655 ext2_put_page(page); 656 } 657 return 1; 658 659 not_empty: 660 ext2_put_page(page); 661 return 0; 662 } 663 664 const struct file_operations ext2_dir_operations = { 665 .llseek = generic_file_llseek, 666 .read = generic_read_dir, 667 .readdir = ext2_readdir, 668 .ioctl = ext2_ioctl, 669 #ifdef CONFIG_COMPAT 670 .compat_ioctl = ext2_compat_ioctl, 671 #endif 672 .fsync = ext2_sync_file, 673 }; 674