1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * linux/fs/ext2/dir.c 4 * 5 * Copyright (C) 1992, 1993, 1994, 1995 6 * Remy Card (card@masi.ibp.fr) 7 * Laboratoire MASI - Institut Blaise Pascal 8 * Universite Pierre et Marie Curie (Paris VI) 9 * 10 * from 11 * 12 * linux/fs/minix/dir.c 13 * 14 * Copyright (C) 1991, 1992 Linus Torvalds 15 * 16 * ext2 directory handling functions 17 * 18 * Big-endian to little-endian byte-swapping/bitmaps by 19 * David S. Miller (davem@caip.rutgers.edu), 1995 20 * 21 * All code that works with directory layout had been switched to pagecache 22 * and moved here. AV 23 */ 24 25 #include "ext2.h" 26 #include <linux/buffer_head.h> 27 #include <linux/pagemap.h> 28 #include <linux/swap.h> 29 #include <linux/iversion.h> 30 31 typedef struct ext2_dir_entry_2 ext2_dirent; 32 33 /* 34 * Tests against MAX_REC_LEN etc were put in place for 64k block 35 * sizes; if that is not possible on this arch, we can skip 36 * those tests and speed things up. 37 */ 38 static inline unsigned ext2_rec_len_from_disk(__le16 dlen) 39 { 40 unsigned len = le16_to_cpu(dlen); 41 42 #if (PAGE_SIZE >= 65536) 43 if (len == EXT2_MAX_REC_LEN) 44 return 1 << 16; 45 #endif 46 return len; 47 } 48 49 static inline __le16 ext2_rec_len_to_disk(unsigned len) 50 { 51 #if (PAGE_SIZE >= 65536) 52 if (len == (1 << 16)) 53 return cpu_to_le16(EXT2_MAX_REC_LEN); 54 else 55 BUG_ON(len > (1 << 16)); 56 #endif 57 return cpu_to_le16(len); 58 } 59 60 /* 61 * ext2 uses block-sized chunks. Arguably, sector-sized ones would be 62 * more robust, but we have what we have 63 */ 64 static inline unsigned ext2_chunk_size(struct inode *inode) 65 { 66 return inode->i_sb->s_blocksize; 67 } 68 69 /* 70 * Return the offset into page `page_nr' of the last valid 71 * byte in that page, plus one. 72 */ 73 static unsigned 74 ext2_last_byte(struct inode *inode, unsigned long page_nr) 75 { 76 unsigned last_byte = inode->i_size; 77 78 last_byte -= page_nr << PAGE_SHIFT; 79 if (last_byte > PAGE_SIZE) 80 last_byte = PAGE_SIZE; 81 return last_byte; 82 } 83 84 static void ext2_commit_chunk(struct page *page, loff_t pos, unsigned len) 85 { 86 struct address_space *mapping = page->mapping; 87 struct inode *dir = mapping->host; 88 89 inode_inc_iversion(dir); 90 block_write_end(NULL, mapping, pos, len, len, page, NULL); 91 92 if (pos+len > dir->i_size) { 93 i_size_write(dir, pos+len); 94 mark_inode_dirty(dir); 95 } 96 unlock_page(page); 97 } 98 99 static bool ext2_check_page(struct page *page, int quiet, char *kaddr) 100 { 101 struct inode *dir = page->mapping->host; 102 struct super_block *sb = dir->i_sb; 103 unsigned chunk_size = ext2_chunk_size(dir); 104 u32 max_inumber = le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count); 105 unsigned offs, rec_len; 106 unsigned limit = PAGE_SIZE; 107 ext2_dirent *p; 108 char *error; 109 110 if ((dir->i_size >> PAGE_SHIFT) == page->index) { 111 limit = dir->i_size & ~PAGE_MASK; 112 if (limit & (chunk_size - 1)) 113 goto Ebadsize; 114 if (!limit) 115 goto out; 116 } 117 for (offs = 0; offs <= limit - EXT2_DIR_REC_LEN(1); offs += rec_len) { 118 p = (ext2_dirent *)(kaddr + offs); 119 rec_len = ext2_rec_len_from_disk(p->rec_len); 120 121 if (unlikely(rec_len < EXT2_DIR_REC_LEN(1))) 122 goto Eshort; 123 if (unlikely(rec_len & 3)) 124 goto Ealign; 125 if (unlikely(rec_len < EXT2_DIR_REC_LEN(p->name_len))) 126 goto Enamelen; 127 if (unlikely(((offs + rec_len - 1) ^ offs) & ~(chunk_size-1))) 128 goto Espan; 129 if (unlikely(le32_to_cpu(p->inode) > max_inumber)) 130 goto Einumber; 131 } 132 if (offs != limit) 133 goto Eend; 134 out: 135 SetPageChecked(page); 136 return true; 137 138 /* Too bad, we had an error */ 139 140 Ebadsize: 141 if (!quiet) 142 ext2_error(sb, __func__, 143 "size of directory #%lu is not a multiple " 144 "of chunk size", dir->i_ino); 145 goto fail; 146 Eshort: 147 error = "rec_len is smaller than minimal"; 148 goto bad_entry; 149 Ealign: 150 error = "unaligned directory entry"; 151 goto bad_entry; 152 Enamelen: 153 error = "rec_len is too small for name_len"; 154 goto bad_entry; 155 Espan: 156 error = "directory entry across blocks"; 157 goto bad_entry; 158 Einumber: 159 error = "inode out of bounds"; 160 bad_entry: 161 if (!quiet) 162 ext2_error(sb, __func__, "bad entry in directory #%lu: : %s - " 163 "offset=%lu, inode=%lu, rec_len=%d, name_len=%d", 164 dir->i_ino, error, (page->index<<PAGE_SHIFT)+offs, 165 (unsigned long) le32_to_cpu(p->inode), 166 rec_len, p->name_len); 167 goto fail; 168 Eend: 169 if (!quiet) { 170 p = (ext2_dirent *)(kaddr + offs); 171 ext2_error(sb, "ext2_check_page", 172 "entry in directory #%lu spans the page boundary" 173 "offset=%lu, inode=%lu", 174 dir->i_ino, (page->index<<PAGE_SHIFT)+offs, 175 (unsigned long) le32_to_cpu(p->inode)); 176 } 177 fail: 178 SetPageError(page); 179 return false; 180 } 181 182 /* 183 * Calls to ext2_get_page()/ext2_put_page() must be nested according to the 184 * rules documented in kmap_local_page()/kunmap_local(). 185 * 186 * NOTE: ext2_find_entry() and ext2_dotdot() act as a call to ext2_get_page() 187 * and should be treated as a call to ext2_get_page() for nesting purposes. 188 */ 189 static void *ext2_get_page(struct inode *dir, unsigned long n, 190 int quiet, struct page **page) 191 { 192 struct address_space *mapping = dir->i_mapping; 193 struct folio *folio = read_mapping_folio(mapping, n, NULL); 194 void *page_addr; 195 196 if (IS_ERR(folio)) 197 return ERR_CAST(folio); 198 page_addr = kmap_local_folio(folio, n & (folio_nr_pages(folio) - 1)); 199 if (unlikely(!folio_test_checked(folio))) { 200 if (!ext2_check_page(&folio->page, quiet, page_addr)) 201 goto fail; 202 } 203 *page = &folio->page; 204 return page_addr; 205 206 fail: 207 ext2_put_page(&folio->page, page_addr); 208 return ERR_PTR(-EIO); 209 } 210 211 /* 212 * NOTE! unlike strncmp, ext2_match returns 1 for success, 0 for failure. 213 * 214 * len <= EXT2_NAME_LEN and de != NULL are guaranteed by caller. 215 */ 216 static inline int ext2_match (int len, const char * const name, 217 struct ext2_dir_entry_2 * de) 218 { 219 if (len != de->name_len) 220 return 0; 221 if (!de->inode) 222 return 0; 223 return !memcmp(name, de->name, len); 224 } 225 226 /* 227 * p is at least 6 bytes before the end of page 228 */ 229 static inline ext2_dirent *ext2_next_entry(ext2_dirent *p) 230 { 231 return (ext2_dirent *)((char *)p + 232 ext2_rec_len_from_disk(p->rec_len)); 233 } 234 235 static inline unsigned 236 ext2_validate_entry(char *base, unsigned offset, unsigned mask) 237 { 238 ext2_dirent *de = (ext2_dirent*)(base + offset); 239 ext2_dirent *p = (ext2_dirent*)(base + (offset&mask)); 240 while ((char*)p < (char*)de) { 241 if (p->rec_len == 0) 242 break; 243 p = ext2_next_entry(p); 244 } 245 return offset_in_page(p); 246 } 247 248 static inline void ext2_set_de_type(ext2_dirent *de, struct inode *inode) 249 { 250 if (EXT2_HAS_INCOMPAT_FEATURE(inode->i_sb, EXT2_FEATURE_INCOMPAT_FILETYPE)) 251 de->file_type = fs_umode_to_ftype(inode->i_mode); 252 else 253 de->file_type = 0; 254 } 255 256 static int 257 ext2_readdir(struct file *file, struct dir_context *ctx) 258 { 259 loff_t pos = ctx->pos; 260 struct inode *inode = file_inode(file); 261 struct super_block *sb = inode->i_sb; 262 unsigned int offset = pos & ~PAGE_MASK; 263 unsigned long n = pos >> PAGE_SHIFT; 264 unsigned long npages = dir_pages(inode); 265 unsigned chunk_mask = ~(ext2_chunk_size(inode)-1); 266 bool need_revalidate = !inode_eq_iversion(inode, file->f_version); 267 bool has_filetype; 268 269 if (pos > inode->i_size - EXT2_DIR_REC_LEN(1)) 270 return 0; 271 272 has_filetype = 273 EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_FILETYPE); 274 275 for ( ; n < npages; n++, offset = 0) { 276 ext2_dirent *de; 277 struct page *page; 278 char *kaddr = ext2_get_page(inode, n, 0, &page); 279 char *limit; 280 281 if (IS_ERR(kaddr)) { 282 ext2_error(sb, __func__, 283 "bad page in #%lu", 284 inode->i_ino); 285 ctx->pos += PAGE_SIZE - offset; 286 return PTR_ERR(kaddr); 287 } 288 if (unlikely(need_revalidate)) { 289 if (offset) { 290 offset = ext2_validate_entry(kaddr, offset, chunk_mask); 291 ctx->pos = (n<<PAGE_SHIFT) + offset; 292 } 293 file->f_version = inode_query_iversion(inode); 294 need_revalidate = false; 295 } 296 de = (ext2_dirent *)(kaddr+offset); 297 limit = kaddr + ext2_last_byte(inode, n) - EXT2_DIR_REC_LEN(1); 298 for ( ;(char*)de <= limit; de = ext2_next_entry(de)) { 299 if (de->rec_len == 0) { 300 ext2_error(sb, __func__, 301 "zero-length directory entry"); 302 ext2_put_page(page, de); 303 return -EIO; 304 } 305 if (de->inode) { 306 unsigned char d_type = DT_UNKNOWN; 307 308 if (has_filetype) 309 d_type = fs_ftype_to_dtype(de->file_type); 310 311 if (!dir_emit(ctx, de->name, de->name_len, 312 le32_to_cpu(de->inode), 313 d_type)) { 314 ext2_put_page(page, de); 315 return 0; 316 } 317 } 318 ctx->pos += ext2_rec_len_from_disk(de->rec_len); 319 } 320 ext2_put_page(page, kaddr); 321 } 322 return 0; 323 } 324 325 /* 326 * ext2_find_entry() 327 * 328 * finds an entry in the specified directory with the wanted name. It 329 * returns the page in which the entry was found (as a parameter - res_page), 330 * and the entry itself. Page is returned mapped and unlocked. 331 * Entry is guaranteed to be valid. 332 * 333 * On Success ext2_put_page() should be called on *res_page. 334 * 335 * NOTE: Calls to ext2_get_page()/ext2_put_page() must be nested according to 336 * the rules documented in kmap_local_page()/kunmap_local(). 337 * 338 * ext2_find_entry() and ext2_dotdot() act as a call to ext2_get_page() and 339 * should be treated as a call to ext2_get_page() for nesting purposes. 340 */ 341 struct ext2_dir_entry_2 *ext2_find_entry (struct inode *dir, 342 const struct qstr *child, struct page **res_page, 343 void **res_page_addr) 344 { 345 const char *name = child->name; 346 int namelen = child->len; 347 unsigned reclen = EXT2_DIR_REC_LEN(namelen); 348 unsigned long start, n; 349 unsigned long npages = dir_pages(dir); 350 struct page *page = NULL; 351 struct ext2_inode_info *ei = EXT2_I(dir); 352 ext2_dirent * de; 353 void *page_addr; 354 355 if (npages == 0) 356 goto out; 357 358 /* OFFSET_CACHE */ 359 *res_page = NULL; 360 *res_page_addr = NULL; 361 362 start = ei->i_dir_start_lookup; 363 if (start >= npages) 364 start = 0; 365 n = start; 366 do { 367 char *kaddr; 368 369 page_addr = ext2_get_page(dir, n, 0, &page); 370 if (IS_ERR(page_addr)) 371 return ERR_CAST(page_addr); 372 373 kaddr = page_addr; 374 de = (ext2_dirent *) kaddr; 375 kaddr += ext2_last_byte(dir, n) - reclen; 376 while ((char *) de <= kaddr) { 377 if (de->rec_len == 0) { 378 ext2_error(dir->i_sb, __func__, 379 "zero-length directory entry"); 380 ext2_put_page(page, de); 381 goto out; 382 } 383 if (ext2_match(namelen, name, de)) 384 goto found; 385 de = ext2_next_entry(de); 386 } 387 ext2_put_page(page, kaddr); 388 389 if (++n >= npages) 390 n = 0; 391 /* next page is past the blocks we've got */ 392 if (unlikely(n > (dir->i_blocks >> (PAGE_SHIFT - 9)))) { 393 ext2_error(dir->i_sb, __func__, 394 "dir %lu size %lld exceeds block count %llu", 395 dir->i_ino, dir->i_size, 396 (unsigned long long)dir->i_blocks); 397 goto out; 398 } 399 } while (n != start); 400 out: 401 return ERR_PTR(-ENOENT); 402 403 found: 404 *res_page = page; 405 *res_page_addr = page_addr; 406 ei->i_dir_start_lookup = n; 407 return de; 408 } 409 410 /* 411 * Return the '..' directory entry and the page in which the entry was found 412 * (as a parameter - p). 413 * 414 * On Success ext2_put_page() should be called on *p. 415 * 416 * NOTE: Calls to ext2_get_page()/ext2_put_page() must be nested according to 417 * the rules documented in kmap_local_page()/kunmap_local(). 418 * 419 * ext2_find_entry() and ext2_dotdot() act as a call to ext2_get_page() and 420 * should be treated as a call to ext2_get_page() for nesting purposes. 421 */ 422 struct ext2_dir_entry_2 *ext2_dotdot(struct inode *dir, struct page **p, 423 void **pa) 424 { 425 void *page_addr = ext2_get_page(dir, 0, 0, p); 426 ext2_dirent *de = NULL; 427 428 if (!IS_ERR(page_addr)) { 429 de = ext2_next_entry((ext2_dirent *) page_addr); 430 *pa = page_addr; 431 } 432 return de; 433 } 434 435 int ext2_inode_by_name(struct inode *dir, const struct qstr *child, ino_t *ino) 436 { 437 struct ext2_dir_entry_2 *de; 438 struct page *page; 439 void *page_addr; 440 441 de = ext2_find_entry(dir, child, &page, &page_addr); 442 if (IS_ERR(de)) 443 return PTR_ERR(de); 444 445 *ino = le32_to_cpu(de->inode); 446 ext2_put_page(page, de); 447 return 0; 448 } 449 450 static int ext2_prepare_chunk(struct page *page, loff_t pos, unsigned len) 451 { 452 return __block_write_begin(page, pos, len, ext2_get_block); 453 } 454 455 456 static int ext2_handle_dirsync(struct inode *dir) 457 { 458 int err; 459 460 err = filemap_write_and_wait(dir->i_mapping); 461 if (!err) 462 err = sync_inode_metadata(dir, 1); 463 return err; 464 } 465 466 int ext2_set_link(struct inode *dir, struct ext2_dir_entry_2 *de, 467 struct page *page, struct inode *inode, bool update_times) 468 { 469 loff_t pos = page_offset(page) + offset_in_page(de); 470 unsigned len = ext2_rec_len_from_disk(de->rec_len); 471 int err; 472 473 lock_page(page); 474 err = ext2_prepare_chunk(page, pos, len); 475 if (err) { 476 unlock_page(page); 477 return err; 478 } 479 de->inode = cpu_to_le32(inode->i_ino); 480 ext2_set_de_type(de, inode); 481 ext2_commit_chunk(page, pos, len); 482 if (update_times) 483 dir->i_mtime = dir->i_ctime = current_time(dir); 484 EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL; 485 mark_inode_dirty(dir); 486 return ext2_handle_dirsync(dir); 487 } 488 489 /* 490 * Parent is locked. 491 */ 492 int ext2_add_link (struct dentry *dentry, struct inode *inode) 493 { 494 struct inode *dir = d_inode(dentry->d_parent); 495 const char *name = dentry->d_name.name; 496 int namelen = dentry->d_name.len; 497 unsigned chunk_size = ext2_chunk_size(dir); 498 unsigned reclen = EXT2_DIR_REC_LEN(namelen); 499 unsigned short rec_len, name_len; 500 struct page *page = NULL; 501 ext2_dirent * de; 502 unsigned long npages = dir_pages(dir); 503 unsigned long n; 504 loff_t pos; 505 int err; 506 507 /* 508 * We take care of directory expansion in the same loop. 509 * This code plays outside i_size, so it locks the page 510 * to protect that region. 511 */ 512 for (n = 0; n <= npages; n++) { 513 char *kaddr; 514 char *dir_end; 515 516 kaddr = ext2_get_page(dir, n, 0, &page); 517 if (IS_ERR(kaddr)) 518 return PTR_ERR(kaddr); 519 lock_page(page); 520 dir_end = kaddr + ext2_last_byte(dir, n); 521 de = (ext2_dirent *)kaddr; 522 kaddr += PAGE_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, kaddr); 551 } 552 BUG(); 553 return -EINVAL; 554 555 got_it: 556 pos = page_offset(page) + offset_in_page(de); 557 err = ext2_prepare_chunk(page, pos, rec_len); 558 if (err) 559 goto out_unlock; 560 if (de->inode) { 561 ext2_dirent *de1 = (ext2_dirent *) ((char *) de + name_len); 562 de1->rec_len = ext2_rec_len_to_disk(rec_len - name_len); 563 de->rec_len = ext2_rec_len_to_disk(name_len); 564 de = de1; 565 } 566 de->name_len = namelen; 567 memcpy(de->name, name, namelen); 568 de->inode = cpu_to_le32(inode->i_ino); 569 ext2_set_de_type (de, inode); 570 ext2_commit_chunk(page, pos, rec_len); 571 dir->i_mtime = dir->i_ctime = current_time(dir); 572 EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL; 573 mark_inode_dirty(dir); 574 err = ext2_handle_dirsync(dir); 575 /* OFFSET_CACHE */ 576 out_put: 577 ext2_put_page(page, de); 578 return err; 579 out_unlock: 580 unlock_page(page); 581 goto out_put; 582 } 583 584 /* 585 * ext2_delete_entry deletes a directory entry by merging it with the 586 * previous entry. Page is up-to-date. 587 */ 588 int ext2_delete_entry(struct ext2_dir_entry_2 *dir, struct page *page) 589 { 590 struct inode *inode = page->mapping->host; 591 char *kaddr = (char *)((unsigned long)dir & PAGE_MASK); 592 unsigned from = offset_in_page(dir) & ~(ext2_chunk_size(inode)-1); 593 unsigned to = offset_in_page(dir) + 594 ext2_rec_len_from_disk(dir->rec_len); 595 loff_t pos; 596 ext2_dirent *pde = NULL; 597 ext2_dirent *de = (ext2_dirent *)(kaddr + from); 598 int err; 599 600 while ((char*)de < (char*)dir) { 601 if (de->rec_len == 0) { 602 ext2_error(inode->i_sb, __func__, 603 "zero-length directory entry"); 604 return -EIO; 605 } 606 pde = de; 607 de = ext2_next_entry(de); 608 } 609 if (pde) 610 from = offset_in_page(pde); 611 pos = page_offset(page) + from; 612 lock_page(page); 613 err = ext2_prepare_chunk(page, pos, to - from); 614 if (err) { 615 unlock_page(page); 616 return err; 617 } 618 if (pde) 619 pde->rec_len = ext2_rec_len_to_disk(to - from); 620 dir->inode = 0; 621 ext2_commit_chunk(page, pos, to - from); 622 inode->i_ctime = inode->i_mtime = current_time(inode); 623 EXT2_I(inode)->i_flags &= ~EXT2_BTREE_FL; 624 mark_inode_dirty(inode); 625 return ext2_handle_dirsync(inode); 626 } 627 628 /* 629 * Set the first fragment of directory. 630 */ 631 int ext2_make_empty(struct inode *inode, struct inode *parent) 632 { 633 struct page *page = grab_cache_page(inode->i_mapping, 0); 634 unsigned chunk_size = ext2_chunk_size(inode); 635 struct ext2_dir_entry_2 * de; 636 int err; 637 void *kaddr; 638 639 if (!page) 640 return -ENOMEM; 641 642 err = ext2_prepare_chunk(page, 0, chunk_size); 643 if (err) { 644 unlock_page(page); 645 goto fail; 646 } 647 kaddr = kmap_local_page(page); 648 memset(kaddr, 0, chunk_size); 649 de = (struct ext2_dir_entry_2 *)kaddr; 650 de->name_len = 1; 651 de->rec_len = ext2_rec_len_to_disk(EXT2_DIR_REC_LEN(1)); 652 memcpy (de->name, ".\0\0", 4); 653 de->inode = cpu_to_le32(inode->i_ino); 654 ext2_set_de_type (de, inode); 655 656 de = (struct ext2_dir_entry_2 *)(kaddr + EXT2_DIR_REC_LEN(1)); 657 de->name_len = 2; 658 de->rec_len = ext2_rec_len_to_disk(chunk_size - EXT2_DIR_REC_LEN(1)); 659 de->inode = cpu_to_le32(parent->i_ino); 660 memcpy (de->name, "..\0", 4); 661 ext2_set_de_type (de, inode); 662 kunmap_local(kaddr); 663 ext2_commit_chunk(page, 0, chunk_size); 664 err = ext2_handle_dirsync(inode); 665 fail: 666 put_page(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; 676 char *kaddr; 677 unsigned long i, npages = dir_pages(inode); 678 679 for (i = 0; i < npages; i++) { 680 ext2_dirent *de; 681 682 kaddr = ext2_get_page(inode, i, 0, &page); 683 if (IS_ERR(kaddr)) 684 return 0; 685 686 de = (ext2_dirent *)kaddr; 687 kaddr += ext2_last_byte(inode, i) - EXT2_DIR_REC_LEN(1); 688 689 while ((char *)de <= kaddr) { 690 if (de->rec_len == 0) { 691 ext2_error(inode->i_sb, __func__, 692 "zero-length directory entry"); 693 printk("kaddr=%p, de=%p\n", kaddr, de); 694 goto not_empty; 695 } 696 if (de->inode != 0) { 697 /* check for . and .. */ 698 if (de->name[0] != '.') 699 goto not_empty; 700 if (de->name_len > 2) 701 goto not_empty; 702 if (de->name_len < 2) { 703 if (de->inode != 704 cpu_to_le32(inode->i_ino)) 705 goto not_empty; 706 } else if (de->name[1] != '.') 707 goto not_empty; 708 } 709 de = ext2_next_entry(de); 710 } 711 ext2_put_page(page, kaddr); 712 } 713 return 1; 714 715 not_empty: 716 ext2_put_page(page, kaddr); 717 return 0; 718 } 719 720 const struct file_operations ext2_dir_operations = { 721 .llseek = generic_file_llseek, 722 .read = generic_read_dir, 723 .iterate_shared = ext2_readdir, 724 .unlocked_ioctl = ext2_ioctl, 725 #ifdef CONFIG_COMPAT 726 .compat_ioctl = ext2_compat_ioctl, 727 #endif 728 .fsync = ext2_fsync, 729 }; 730