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/buffer_head.h> 26 #include <linux/pagemap.h> 27 #include <linux/swap.h> 28 29 typedef struct ext2_dir_entry_2 ext2_dirent; 30 31 /* 32 * Tests against MAX_REC_LEN etc were put in place for 64k block 33 * sizes; if that is not possible on this arch, we can skip 34 * those tests and speed things up. 35 */ 36 static inline unsigned ext2_rec_len_from_disk(__le16 dlen) 37 { 38 unsigned len = le16_to_cpu(dlen); 39 40 #if (PAGE_CACHE_SIZE >= 65536) 41 if (len == EXT2_MAX_REC_LEN) 42 return 1 << 16; 43 #endif 44 return len; 45 } 46 47 static inline __le16 ext2_rec_len_to_disk(unsigned len) 48 { 49 #if (PAGE_CACHE_SIZE >= 65536) 50 if (len == (1 << 16)) 51 return cpu_to_le16(EXT2_MAX_REC_LEN); 52 else 53 BUG_ON(len > (1 << 16)); 54 #endif 55 return cpu_to_le16(len); 56 } 57 58 /* 59 * ext2 uses block-sized chunks. Arguably, sector-sized ones would be 60 * more robust, but we have what we have 61 */ 62 static inline unsigned ext2_chunk_size(struct inode *inode) 63 { 64 return inode->i_sb->s_blocksize; 65 } 66 67 static inline void ext2_put_page(struct page *page) 68 { 69 kunmap(page); 70 page_cache_release(page); 71 } 72 73 static inline unsigned long dir_pages(struct inode *inode) 74 { 75 return (inode->i_size+PAGE_CACHE_SIZE-1)>>PAGE_CACHE_SHIFT; 76 } 77 78 /* 79 * Return the offset into page `page_nr' of the last valid 80 * byte in that page, plus one. 81 */ 82 static unsigned 83 ext2_last_byte(struct inode *inode, unsigned long page_nr) 84 { 85 unsigned last_byte = inode->i_size; 86 87 last_byte -= page_nr << PAGE_CACHE_SHIFT; 88 if (last_byte > PAGE_CACHE_SIZE) 89 last_byte = PAGE_CACHE_SIZE; 90 return last_byte; 91 } 92 93 static int ext2_commit_chunk(struct page *page, loff_t pos, unsigned len) 94 { 95 struct address_space *mapping = page->mapping; 96 struct inode *dir = mapping->host; 97 int err = 0; 98 99 dir->i_version++; 100 block_write_end(NULL, mapping, pos, len, len, page, NULL); 101 102 if (pos+len > dir->i_size) { 103 i_size_write(dir, pos+len); 104 mark_inode_dirty(dir); 105 } 106 107 if (IS_DIRSYNC(dir)) { 108 err = write_one_page(page, 1); 109 if (!err) 110 err = sync_inode_metadata(dir, 1); 111 } else { 112 unlock_page(page); 113 } 114 115 return err; 116 } 117 118 static void ext2_check_page(struct page *page, int quiet) 119 { 120 struct inode *dir = page->mapping->host; 121 struct super_block *sb = dir->i_sb; 122 unsigned chunk_size = ext2_chunk_size(dir); 123 char *kaddr = page_address(page); 124 u32 max_inumber = le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count); 125 unsigned offs, rec_len; 126 unsigned limit = PAGE_CACHE_SIZE; 127 ext2_dirent *p; 128 char *error; 129 130 if ((dir->i_size >> PAGE_CACHE_SHIFT) == page->index) { 131 limit = dir->i_size & ~PAGE_CACHE_MASK; 132 if (limit & (chunk_size - 1)) 133 goto Ebadsize; 134 if (!limit) 135 goto out; 136 } 137 for (offs = 0; offs <= limit - EXT2_DIR_REC_LEN(1); offs += rec_len) { 138 p = (ext2_dirent *)(kaddr + offs); 139 rec_len = ext2_rec_len_from_disk(p->rec_len); 140 141 if (unlikely(rec_len < EXT2_DIR_REC_LEN(1))) 142 goto Eshort; 143 if (unlikely(rec_len & 3)) 144 goto Ealign; 145 if (unlikely(rec_len < EXT2_DIR_REC_LEN(p->name_len))) 146 goto Enamelen; 147 if (unlikely(((offs + rec_len - 1) ^ offs) & ~(chunk_size-1))) 148 goto Espan; 149 if (unlikely(le32_to_cpu(p->inode) > max_inumber)) 150 goto Einumber; 151 } 152 if (offs != limit) 153 goto Eend; 154 out: 155 SetPageChecked(page); 156 return; 157 158 /* Too bad, we had an error */ 159 160 Ebadsize: 161 if (!quiet) 162 ext2_error(sb, __func__, 163 "size of directory #%lu is not a multiple " 164 "of chunk size", dir->i_ino); 165 goto fail; 166 Eshort: 167 error = "rec_len is smaller than minimal"; 168 goto bad_entry; 169 Ealign: 170 error = "unaligned directory entry"; 171 goto bad_entry; 172 Enamelen: 173 error = "rec_len is too small for name_len"; 174 goto bad_entry; 175 Espan: 176 error = "directory entry across blocks"; 177 goto bad_entry; 178 Einumber: 179 error = "inode out of bounds"; 180 bad_entry: 181 if (!quiet) 182 ext2_error(sb, __func__, "bad entry in directory #%lu: : %s - " 183 "offset=%lu, inode=%lu, rec_len=%d, name_len=%d", 184 dir->i_ino, error, (page->index<<PAGE_CACHE_SHIFT)+offs, 185 (unsigned long) le32_to_cpu(p->inode), 186 rec_len, p->name_len); 187 goto fail; 188 Eend: 189 if (!quiet) { 190 p = (ext2_dirent *)(kaddr + offs); 191 ext2_error(sb, "ext2_check_page", 192 "entry in directory #%lu spans the page boundary" 193 "offset=%lu, inode=%lu", 194 dir->i_ino, (page->index<<PAGE_CACHE_SHIFT)+offs, 195 (unsigned long) le32_to_cpu(p->inode)); 196 } 197 fail: 198 SetPageChecked(page); 199 SetPageError(page); 200 } 201 202 static struct page * ext2_get_page(struct inode *dir, unsigned long n, 203 int quiet) 204 { 205 struct address_space *mapping = dir->i_mapping; 206 struct page *page = read_mapping_page(mapping, n, NULL); 207 if (!IS_ERR(page)) { 208 kmap(page); 209 if (!PageChecked(page)) 210 ext2_check_page(page, quiet); 211 if (PageError(page)) 212 goto fail; 213 } 214 return page; 215 216 fail: 217 ext2_put_page(page); 218 return ERR_PTR(-EIO); 219 } 220 221 /* 222 * NOTE! unlike strncmp, ext2_match returns 1 for success, 0 for failure. 223 * 224 * len <= EXT2_NAME_LEN and de != NULL are guaranteed by caller. 225 */ 226 static inline int ext2_match (int len, const char * const name, 227 struct ext2_dir_entry_2 * de) 228 { 229 if (len != de->name_len) 230 return 0; 231 if (!de->inode) 232 return 0; 233 return !memcmp(name, de->name, len); 234 } 235 236 /* 237 * p is at least 6 bytes before the end of page 238 */ 239 static inline ext2_dirent *ext2_next_entry(ext2_dirent *p) 240 { 241 return (ext2_dirent *)((char *)p + 242 ext2_rec_len_from_disk(p->rec_len)); 243 } 244 245 static inline unsigned 246 ext2_validate_entry(char *base, unsigned offset, unsigned mask) 247 { 248 ext2_dirent *de = (ext2_dirent*)(base + offset); 249 ext2_dirent *p = (ext2_dirent*)(base + (offset&mask)); 250 while ((char*)p < (char*)de) { 251 if (p->rec_len == 0) 252 break; 253 p = ext2_next_entry(p); 254 } 255 return (char *)p - base; 256 } 257 258 static unsigned char ext2_filetype_table[EXT2_FT_MAX] = { 259 [EXT2_FT_UNKNOWN] = DT_UNKNOWN, 260 [EXT2_FT_REG_FILE] = DT_REG, 261 [EXT2_FT_DIR] = DT_DIR, 262 [EXT2_FT_CHRDEV] = DT_CHR, 263 [EXT2_FT_BLKDEV] = DT_BLK, 264 [EXT2_FT_FIFO] = DT_FIFO, 265 [EXT2_FT_SOCK] = DT_SOCK, 266 [EXT2_FT_SYMLINK] = DT_LNK, 267 }; 268 269 #define S_SHIFT 12 270 static unsigned char ext2_type_by_mode[S_IFMT >> S_SHIFT] = { 271 [S_IFREG >> S_SHIFT] = EXT2_FT_REG_FILE, 272 [S_IFDIR >> S_SHIFT] = EXT2_FT_DIR, 273 [S_IFCHR >> S_SHIFT] = EXT2_FT_CHRDEV, 274 [S_IFBLK >> S_SHIFT] = EXT2_FT_BLKDEV, 275 [S_IFIFO >> S_SHIFT] = EXT2_FT_FIFO, 276 [S_IFSOCK >> S_SHIFT] = EXT2_FT_SOCK, 277 [S_IFLNK >> S_SHIFT] = EXT2_FT_SYMLINK, 278 }; 279 280 static inline void ext2_set_de_type(ext2_dirent *de, struct inode *inode) 281 { 282 mode_t mode = inode->i_mode; 283 if (EXT2_HAS_INCOMPAT_FEATURE(inode->i_sb, EXT2_FEATURE_INCOMPAT_FILETYPE)) 284 de->file_type = ext2_type_by_mode[(mode & S_IFMT)>>S_SHIFT]; 285 else 286 de->file_type = 0; 287 } 288 289 static int 290 ext2_readdir (struct file * filp, void * dirent, filldir_t filldir) 291 { 292 loff_t pos = filp->f_pos; 293 struct inode *inode = filp->f_path.dentry->d_inode; 294 struct super_block *sb = inode->i_sb; 295 unsigned int offset = pos & ~PAGE_CACHE_MASK; 296 unsigned long n = pos >> PAGE_CACHE_SHIFT; 297 unsigned long npages = dir_pages(inode); 298 unsigned chunk_mask = ~(ext2_chunk_size(inode)-1); 299 unsigned char *types = NULL; 300 int need_revalidate = filp->f_version != inode->i_version; 301 302 if (pos > inode->i_size - EXT2_DIR_REC_LEN(1)) 303 return 0; 304 305 if (EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_FILETYPE)) 306 types = ext2_filetype_table; 307 308 for ( ; n < npages; n++, offset = 0) { 309 char *kaddr, *limit; 310 ext2_dirent *de; 311 struct page *page = ext2_get_page(inode, n, 0); 312 313 if (IS_ERR(page)) { 314 ext2_error(sb, __func__, 315 "bad page in #%lu", 316 inode->i_ino); 317 filp->f_pos += PAGE_CACHE_SIZE - offset; 318 return PTR_ERR(page); 319 } 320 kaddr = page_address(page); 321 if (unlikely(need_revalidate)) { 322 if (offset) { 323 offset = ext2_validate_entry(kaddr, offset, chunk_mask); 324 filp->f_pos = (n<<PAGE_CACHE_SHIFT) + offset; 325 } 326 filp->f_version = inode->i_version; 327 need_revalidate = 0; 328 } 329 de = (ext2_dirent *)(kaddr+offset); 330 limit = kaddr + ext2_last_byte(inode, n) - EXT2_DIR_REC_LEN(1); 331 for ( ;(char*)de <= limit; de = ext2_next_entry(de)) { 332 if (de->rec_len == 0) { 333 ext2_error(sb, __func__, 334 "zero-length directory entry"); 335 ext2_put_page(page); 336 return -EIO; 337 } 338 if (de->inode) { 339 int over; 340 unsigned char d_type = DT_UNKNOWN; 341 342 if (types && de->file_type < EXT2_FT_MAX) 343 d_type = types[de->file_type]; 344 345 offset = (char *)de - kaddr; 346 over = filldir(dirent, de->name, de->name_len, 347 (n<<PAGE_CACHE_SHIFT) | offset, 348 le32_to_cpu(de->inode), d_type); 349 if (over) { 350 ext2_put_page(page); 351 return 0; 352 } 353 } 354 filp->f_pos += ext2_rec_len_from_disk(de->rec_len); 355 } 356 ext2_put_page(page); 357 } 358 return 0; 359 } 360 361 /* 362 * ext2_find_entry() 363 * 364 * finds an entry in the specified directory with the wanted name. It 365 * returns the page in which the entry was found (as a parameter - res_page), 366 * and the entry itself. Page is returned mapped and unlocked. 367 * Entry is guaranteed to be valid. 368 */ 369 struct ext2_dir_entry_2 *ext2_find_entry (struct inode * dir, 370 struct qstr *child, struct page ** res_page) 371 { 372 const char *name = child->name; 373 int namelen = child->len; 374 unsigned reclen = EXT2_DIR_REC_LEN(namelen); 375 unsigned long start, n; 376 unsigned long npages = dir_pages(dir); 377 struct page *page = NULL; 378 struct ext2_inode_info *ei = EXT2_I(dir); 379 ext2_dirent * de; 380 int dir_has_error = 0; 381 382 if (npages == 0) 383 goto out; 384 385 /* OFFSET_CACHE */ 386 *res_page = NULL; 387 388 start = ei->i_dir_start_lookup; 389 if (start >= npages) 390 start = 0; 391 n = start; 392 do { 393 char *kaddr; 394 page = ext2_get_page(dir, n, dir_has_error); 395 if (!IS_ERR(page)) { 396 kaddr = page_address(page); 397 de = (ext2_dirent *) kaddr; 398 kaddr += ext2_last_byte(dir, n) - reclen; 399 while ((char *) de <= kaddr) { 400 if (de->rec_len == 0) { 401 ext2_error(dir->i_sb, __func__, 402 "zero-length directory entry"); 403 ext2_put_page(page); 404 goto out; 405 } 406 if (ext2_match (namelen, name, de)) 407 goto found; 408 de = ext2_next_entry(de); 409 } 410 ext2_put_page(page); 411 } else 412 dir_has_error = 1; 413 414 if (++n >= npages) 415 n = 0; 416 /* next page is past the blocks we've got */ 417 if (unlikely(n > (dir->i_blocks >> (PAGE_CACHE_SHIFT - 9)))) { 418 ext2_error(dir->i_sb, __func__, 419 "dir %lu size %lld exceeds block count %llu", 420 dir->i_ino, dir->i_size, 421 (unsigned long long)dir->i_blocks); 422 goto out; 423 } 424 } while (n != start); 425 out: 426 return NULL; 427 428 found: 429 *res_page = page; 430 ei->i_dir_start_lookup = n; 431 return de; 432 } 433 434 struct ext2_dir_entry_2 * ext2_dotdot (struct inode *dir, struct page **p) 435 { 436 struct page *page = ext2_get_page(dir, 0, 0); 437 ext2_dirent *de = NULL; 438 439 if (!IS_ERR(page)) { 440 de = ext2_next_entry((ext2_dirent *) page_address(page)); 441 *p = page; 442 } 443 return de; 444 } 445 446 ino_t ext2_inode_by_name(struct inode *dir, struct qstr *child) 447 { 448 ino_t res = 0; 449 struct ext2_dir_entry_2 *de; 450 struct page *page; 451 452 de = ext2_find_entry (dir, child, &page); 453 if (de) { 454 res = le32_to_cpu(de->inode); 455 ext2_put_page(page); 456 } 457 return res; 458 } 459 460 static int ext2_prepare_chunk(struct page *page, loff_t pos, unsigned len) 461 { 462 return __block_write_begin(page, pos, len, ext2_get_block); 463 } 464 465 /* Releases the page */ 466 void ext2_set_link(struct inode *dir, struct ext2_dir_entry_2 *de, 467 struct page *page, struct inode *inode, int update_times) 468 { 469 loff_t pos = page_offset(page) + 470 (char *) de - (char *) page_address(page); 471 unsigned len = ext2_rec_len_from_disk(de->rec_len); 472 int err; 473 474 lock_page(page); 475 err = ext2_prepare_chunk(page, pos, len); 476 BUG_ON(err); 477 de->inode = cpu_to_le32(inode->i_ino); 478 ext2_set_de_type(de, inode); 479 err = ext2_commit_chunk(page, pos, len); 480 ext2_put_page(page); 481 if (update_times) 482 dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC; 483 EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL; 484 mark_inode_dirty(dir); 485 } 486 487 /* 488 * Parent is locked. 489 */ 490 int ext2_add_link (struct dentry *dentry, struct inode *inode) 491 { 492 struct inode *dir = dentry->d_parent->d_inode; 493 const char *name = dentry->d_name.name; 494 int namelen = dentry->d_name.len; 495 unsigned chunk_size = ext2_chunk_size(dir); 496 unsigned reclen = EXT2_DIR_REC_LEN(namelen); 497 unsigned short rec_len, name_len; 498 struct page *page = NULL; 499 ext2_dirent * de; 500 unsigned long npages = dir_pages(dir); 501 unsigned long n; 502 char *kaddr; 503 loff_t pos; 504 int err; 505 506 /* 507 * We take care of directory expansion in the same loop. 508 * This code plays outside i_size, so it locks the page 509 * to protect that region. 510 */ 511 for (n = 0; n <= npages; n++) { 512 char *dir_end; 513 514 page = ext2_get_page(dir, n, 0); 515 err = PTR_ERR(page); 516 if (IS_ERR(page)) 517 goto out; 518 lock_page(page); 519 kaddr = page_address(page); 520 dir_end = kaddr + ext2_last_byte(dir, n); 521 de = (ext2_dirent *)kaddr; 522 kaddr += PAGE_CACHE_SIZE - reclen; 523 while ((char *)de <= kaddr) { 524 if ((char *)de == dir_end) { 525 /* We hit i_size */ 526 name_len = 0; 527 rec_len = chunk_size; 528 de->rec_len = ext2_rec_len_to_disk(chunk_size); 529 de->inode = 0; 530 goto got_it; 531 } 532 if (de->rec_len == 0) { 533 ext2_error(dir->i_sb, __func__, 534 "zero-length directory entry"); 535 err = -EIO; 536 goto out_unlock; 537 } 538 err = -EEXIST; 539 if (ext2_match (namelen, name, de)) 540 goto out_unlock; 541 name_len = EXT2_DIR_REC_LEN(de->name_len); 542 rec_len = ext2_rec_len_from_disk(de->rec_len); 543 if (!de->inode && rec_len >= reclen) 544 goto got_it; 545 if (rec_len >= name_len + reclen) 546 goto got_it; 547 de = (ext2_dirent *) ((char *) de + rec_len); 548 } 549 unlock_page(page); 550 ext2_put_page(page); 551 } 552 BUG(); 553 return -EINVAL; 554 555 got_it: 556 pos = page_offset(page) + 557 (char*)de - (char*)page_address(page); 558 err = ext2_prepare_chunk(page, pos, rec_len); 559 if (err) 560 goto out_unlock; 561 if (de->inode) { 562 ext2_dirent *de1 = (ext2_dirent *) ((char *) de + name_len); 563 de1->rec_len = ext2_rec_len_to_disk(rec_len - name_len); 564 de->rec_len = ext2_rec_len_to_disk(name_len); 565 de = de1; 566 } 567 de->name_len = namelen; 568 memcpy(de->name, name, namelen); 569 de->inode = cpu_to_le32(inode->i_ino); 570 ext2_set_de_type (de, inode); 571 err = ext2_commit_chunk(page, pos, rec_len); 572 dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC; 573 EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL; 574 mark_inode_dirty(dir); 575 /* OFFSET_CACHE */ 576 out_put: 577 ext2_put_page(page); 578 out: 579 return err; 580 out_unlock: 581 unlock_page(page); 582 goto out_put; 583 } 584 585 /* 586 * ext2_delete_entry deletes a directory entry by merging it with the 587 * previous entry. Page is up-to-date. Releases the page. 588 */ 589 int ext2_delete_entry (struct ext2_dir_entry_2 * dir, struct page * page ) 590 { 591 struct inode *inode = page->mapping->host; 592 char *kaddr = page_address(page); 593 unsigned from = ((char*)dir - kaddr) & ~(ext2_chunk_size(inode)-1); 594 unsigned to = ((char *)dir - kaddr) + 595 ext2_rec_len_from_disk(dir->rec_len); 596 loff_t pos; 597 ext2_dirent * pde = NULL; 598 ext2_dirent * de = (ext2_dirent *) (kaddr + from); 599 int err; 600 601 while ((char*)de < (char*)dir) { 602 if (de->rec_len == 0) { 603 ext2_error(inode->i_sb, __func__, 604 "zero-length directory entry"); 605 err = -EIO; 606 goto out; 607 } 608 pde = de; 609 de = ext2_next_entry(de); 610 } 611 if (pde) 612 from = (char*)pde - (char*)page_address(page); 613 pos = page_offset(page) + from; 614 lock_page(page); 615 err = ext2_prepare_chunk(page, pos, to - from); 616 BUG_ON(err); 617 if (pde) 618 pde->rec_len = ext2_rec_len_to_disk(to - from); 619 dir->inode = 0; 620 err = ext2_commit_chunk(page, pos, to - from); 621 inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC; 622 EXT2_I(inode)->i_flags &= ~EXT2_BTREE_FL; 623 mark_inode_dirty(inode); 624 out: 625 ext2_put_page(page); 626 return err; 627 } 628 629 /* 630 * Set the first fragment of directory. 631 */ 632 int ext2_make_empty(struct inode *inode, struct inode *parent) 633 { 634 struct page *page = grab_cache_page(inode->i_mapping, 0); 635 unsigned chunk_size = ext2_chunk_size(inode); 636 struct ext2_dir_entry_2 * de; 637 int err; 638 void *kaddr; 639 640 if (!page) 641 return -ENOMEM; 642 643 err = ext2_prepare_chunk(page, 0, chunk_size); 644 if (err) { 645 unlock_page(page); 646 goto fail; 647 } 648 kaddr = kmap_atomic(page, KM_USER0); 649 memset(kaddr, 0, chunk_size); 650 de = (struct ext2_dir_entry_2 *)kaddr; 651 de->name_len = 1; 652 de->rec_len = ext2_rec_len_to_disk(EXT2_DIR_REC_LEN(1)); 653 memcpy (de->name, ".\0\0", 4); 654 de->inode = cpu_to_le32(inode->i_ino); 655 ext2_set_de_type (de, inode); 656 657 de = (struct ext2_dir_entry_2 *)(kaddr + EXT2_DIR_REC_LEN(1)); 658 de->name_len = 2; 659 de->rec_len = ext2_rec_len_to_disk(chunk_size - EXT2_DIR_REC_LEN(1)); 660 de->inode = cpu_to_le32(parent->i_ino); 661 memcpy (de->name, "..\0", 4); 662 ext2_set_de_type (de, inode); 663 kunmap_atomic(kaddr, KM_USER0); 664 err = ext2_commit_chunk(page, 0, chunk_size); 665 fail: 666 page_cache_release(page); 667 return err; 668 } 669 670 /* 671 * routine to check that the specified directory is empty (for rmdir) 672 */ 673 int ext2_empty_dir (struct inode * inode) 674 { 675 struct page *page = NULL; 676 unsigned long i, npages = dir_pages(inode); 677 int dir_has_error = 0; 678 679 for (i = 0; i < npages; i++) { 680 char *kaddr; 681 ext2_dirent * de; 682 page = ext2_get_page(inode, i, dir_has_error); 683 684 if (IS_ERR(page)) { 685 dir_has_error = 1; 686 continue; 687 } 688 689 kaddr = page_address(page); 690 de = (ext2_dirent *)kaddr; 691 kaddr += ext2_last_byte(inode, i) - EXT2_DIR_REC_LEN(1); 692 693 while ((char *)de <= kaddr) { 694 if (de->rec_len == 0) { 695 ext2_error(inode->i_sb, __func__, 696 "zero-length directory entry"); 697 printk("kaddr=%p, de=%p\n", kaddr, de); 698 goto not_empty; 699 } 700 if (de->inode != 0) { 701 /* check for . and .. */ 702 if (de->name[0] != '.') 703 goto not_empty; 704 if (de->name_len > 2) 705 goto not_empty; 706 if (de->name_len < 2) { 707 if (de->inode != 708 cpu_to_le32(inode->i_ino)) 709 goto not_empty; 710 } else if (de->name[1] != '.') 711 goto not_empty; 712 } 713 de = ext2_next_entry(de); 714 } 715 ext2_put_page(page); 716 } 717 return 1; 718 719 not_empty: 720 ext2_put_page(page); 721 return 0; 722 } 723 724 const struct file_operations ext2_dir_operations = { 725 .llseek = generic_file_llseek, 726 .read = generic_read_dir, 727 .readdir = ext2_readdir, 728 .unlocked_ioctl = ext2_ioctl, 729 #ifdef CONFIG_COMPAT 730 .compat_ioctl = ext2_compat_ioctl, 731 #endif 732 .fsync = ext2_fsync, 733 }; 734