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 31typedef 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 */ 38static 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 49static 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 */ 64static 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 */ 73static unsigned 74ext2_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 84static 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 99static 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; 134out: 135 SetPageChecked(page); 136 return true; 137 138 /* Too bad, we had an error */ 139 140Ebadsize: 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; 146Eshort: 147 error = "rec_len is smaller than minimal"; 148 goto bad_entry; 149Ealign: 150 error = "unaligned directory entry"; 151 goto bad_entry; 152Enamelen: 153 error = "rec_len is too small for name_len"; 154 goto bad_entry; 155Espan: 156 error = "directory entry across blocks"; 157 goto bad_entry; 158Einumber: 159 error = "inode out of bounds"; 160bad_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; 168Eend: 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 } 177fail: 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 */ 189static 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 206fail: 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 */ 216static 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 */ 229static 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 235static inline unsigned 236ext2_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 248static 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 256static int 257ext2_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 */ 341struct ext2_dir_entry_2 *ext2_find_entry (struct inode *dir, 342 const struct qstr *child, struct page **res_page) 343{ 344 const char *name = child->name; 345 int namelen = child->len; 346 unsigned reclen = EXT2_DIR_REC_LEN(namelen); 347 unsigned long start, n; 348 unsigned long npages = dir_pages(dir); 349 struct page *page = NULL; 350 struct ext2_inode_info *ei = EXT2_I(dir); 351 ext2_dirent * de; 352 353 if (npages == 0) 354 goto out; 355 356 /* OFFSET_CACHE */ 357 *res_page = NULL; 358 359 start = ei->i_dir_start_lookup; 360 if (start >= npages) 361 start = 0; 362 n = start; 363 do { 364 char *kaddr = ext2_get_page(dir, n, 0, &page); 365 if (IS_ERR(kaddr)) 366 return ERR_CAST(kaddr); 367 368 de = (ext2_dirent *) kaddr; 369 kaddr += ext2_last_byte(dir, n) - reclen; 370 while ((char *) de <= kaddr) { 371 if (de->rec_len == 0) { 372 ext2_error(dir->i_sb, __func__, 373 "zero-length directory entry"); 374 ext2_put_page(page, de); 375 goto out; 376 } 377 if (ext2_match(namelen, name, de)) 378 goto found; 379 de = ext2_next_entry(de); 380 } 381 ext2_put_page(page, kaddr); 382 383 if (++n >= npages) 384 n = 0; 385 /* next page is past the blocks we've got */ 386 if (unlikely(n > (dir->i_blocks >> (PAGE_SHIFT - 9)))) { 387 ext2_error(dir->i_sb, __func__, 388 "dir %lu size %lld exceeds block count %llu", 389 dir->i_ino, dir->i_size, 390 (unsigned long long)dir->i_blocks); 391 goto out; 392 } 393 } while (n != start); 394out: 395 return ERR_PTR(-ENOENT); 396 397found: 398 *res_page = page; 399 ei->i_dir_start_lookup = n; 400 return de; 401} 402 403/* 404 * Return the '..' directory entry and the page in which the entry was found 405 * (as a parameter - p). 406 * 407 * On Success ext2_put_page() should be called on *p. 408 * 409 * NOTE: Calls to ext2_get_page()/ext2_put_page() must be nested according to 410 * the rules documented in kmap_local_page()/kunmap_local(). 411 * 412 * ext2_find_entry() and ext2_dotdot() act as a call to ext2_get_page() and 413 * should be treated as a call to ext2_get_page() for nesting purposes. 414 */ 415struct ext2_dir_entry_2 *ext2_dotdot(struct inode *dir, struct page **p) 416{ 417 ext2_dirent *de = ext2_get_page(dir, 0, 0, p); 418 419 if (!IS_ERR(de)) 420 return ext2_next_entry(de); 421 return NULL; 422} 423 424int ext2_inode_by_name(struct inode *dir, const struct qstr *child, ino_t *ino) 425{ 426 struct ext2_dir_entry_2 *de; 427 struct page *page; 428 429 de = ext2_find_entry(dir, child, &page); 430 if (IS_ERR(de)) 431 return PTR_ERR(de); 432 433 *ino = le32_to_cpu(de->inode); 434 ext2_put_page(page, de); 435 return 0; 436} 437 438static int ext2_prepare_chunk(struct page *page, loff_t pos, unsigned len) 439{ 440 return __block_write_begin(page, pos, len, ext2_get_block); 441} 442 443 444static int ext2_handle_dirsync(struct inode *dir) 445{ 446 int err; 447 448 err = filemap_write_and_wait(dir->i_mapping); 449 if (!err) 450 err = sync_inode_metadata(dir, 1); 451 return err; 452} 453 454int ext2_set_link(struct inode *dir, struct ext2_dir_entry_2 *de, 455 struct page *page, struct inode *inode, bool update_times) 456{ 457 loff_t pos = page_offset(page) + offset_in_page(de); 458 unsigned len = ext2_rec_len_from_disk(de->rec_len); 459 int err; 460 461 lock_page(page); 462 err = ext2_prepare_chunk(page, pos, len); 463 if (err) { 464 unlock_page(page); 465 return err; 466 } 467 de->inode = cpu_to_le32(inode->i_ino); 468 ext2_set_de_type(de, inode); 469 ext2_commit_chunk(page, pos, len); 470 if (update_times) 471 dir->i_mtime = inode_set_ctime_current(dir); 472 EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL; 473 mark_inode_dirty(dir); 474 return ext2_handle_dirsync(dir); 475} 476 477/* 478 * Parent is locked. 479 */ 480int ext2_add_link (struct dentry *dentry, struct inode *inode) 481{ 482 struct inode *dir = d_inode(dentry->d_parent); 483 const char *name = dentry->d_name.name; 484 int namelen = dentry->d_name.len; 485 unsigned chunk_size = ext2_chunk_size(dir); 486 unsigned reclen = EXT2_DIR_REC_LEN(namelen); 487 unsigned short rec_len, name_len; 488 struct page *page = NULL; 489 ext2_dirent * de; 490 unsigned long npages = dir_pages(dir); 491 unsigned long n; 492 loff_t pos; 493 int err; 494 495 /* 496 * We take care of directory expansion in the same loop. 497 * This code plays outside i_size, so it locks the page 498 * to protect that region. 499 */ 500 for (n = 0; n <= npages; n++) { 501 char *kaddr = ext2_get_page(dir, n, 0, &page); 502 char *dir_end; 503 504 if (IS_ERR(kaddr)) 505 return PTR_ERR(kaddr); 506 lock_page(page); 507 dir_end = kaddr + ext2_last_byte(dir, n); 508 de = (ext2_dirent *)kaddr; 509 kaddr += PAGE_SIZE - reclen; 510 while ((char *)de <= kaddr) { 511 if ((char *)de == dir_end) { 512 /* We hit i_size */ 513 name_len = 0; 514 rec_len = chunk_size; 515 de->rec_len = ext2_rec_len_to_disk(chunk_size); 516 de->inode = 0; 517 goto got_it; 518 } 519 if (de->rec_len == 0) { 520 ext2_error(dir->i_sb, __func__, 521 "zero-length directory entry"); 522 err = -EIO; 523 goto out_unlock; 524 } 525 err = -EEXIST; 526 if (ext2_match (namelen, name, de)) 527 goto out_unlock; 528 name_len = EXT2_DIR_REC_LEN(de->name_len); 529 rec_len = ext2_rec_len_from_disk(de->rec_len); 530 if (!de->inode && rec_len >= reclen) 531 goto got_it; 532 if (rec_len >= name_len + reclen) 533 goto got_it; 534 de = (ext2_dirent *) ((char *) de + rec_len); 535 } 536 unlock_page(page); 537 ext2_put_page(page, kaddr); 538 } 539 BUG(); 540 return -EINVAL; 541 542got_it: 543 pos = page_offset(page) + offset_in_page(de); 544 err = ext2_prepare_chunk(page, pos, rec_len); 545 if (err) 546 goto out_unlock; 547 if (de->inode) { 548 ext2_dirent *de1 = (ext2_dirent *) ((char *) de + name_len); 549 de1->rec_len = ext2_rec_len_to_disk(rec_len - name_len); 550 de->rec_len = ext2_rec_len_to_disk(name_len); 551 de = de1; 552 } 553 de->name_len = namelen; 554 memcpy(de->name, name, namelen); 555 de->inode = cpu_to_le32(inode->i_ino); 556 ext2_set_de_type (de, inode); 557 ext2_commit_chunk(page, pos, rec_len); 558 dir->i_mtime = inode_set_ctime_current(dir); 559 EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL; 560 mark_inode_dirty(dir); 561 err = ext2_handle_dirsync(dir); 562 /* OFFSET_CACHE */ 563out_put: 564 ext2_put_page(page, de); 565 return err; 566out_unlock: 567 unlock_page(page); 568 goto out_put; 569} 570 571/* 572 * ext2_delete_entry deletes a directory entry by merging it with the 573 * previous entry. Page is up-to-date. 574 */ 575int ext2_delete_entry(struct ext2_dir_entry_2 *dir, struct page *page) 576{ 577 struct inode *inode = page->mapping->host; 578 char *kaddr = (char *)((unsigned long)dir & PAGE_MASK); 579 unsigned from = offset_in_page(dir) & ~(ext2_chunk_size(inode)-1); 580 unsigned to = offset_in_page(dir) + 581 ext2_rec_len_from_disk(dir->rec_len); 582 loff_t pos; 583 ext2_dirent *pde = NULL; 584 ext2_dirent *de = (ext2_dirent *)(kaddr + from); 585 int err; 586 587 while ((char*)de < (char*)dir) { 588 if (de->rec_len == 0) { 589 ext2_error(inode->i_sb, __func__, 590 "zero-length directory entry"); 591 return -EIO; 592 } 593 pde = de; 594 de = ext2_next_entry(de); 595 } 596 if (pde) 597 from = offset_in_page(pde); 598 pos = page_offset(page) + from; 599 lock_page(page); 600 err = ext2_prepare_chunk(page, pos, to - from); 601 if (err) { 602 unlock_page(page); 603 return err; 604 } 605 if (pde) 606 pde->rec_len = ext2_rec_len_to_disk(to - from); 607 dir->inode = 0; 608 ext2_commit_chunk(page, pos, to - from); 609 inode->i_mtime = inode_set_ctime_current(inode); 610 EXT2_I(inode)->i_flags &= ~EXT2_BTREE_FL; 611 mark_inode_dirty(inode); 612 return ext2_handle_dirsync(inode); 613} 614 615/* 616 * Set the first fragment of directory. 617 */ 618int ext2_make_empty(struct inode *inode, struct inode *parent) 619{ 620 struct page *page = grab_cache_page(inode->i_mapping, 0); 621 unsigned chunk_size = ext2_chunk_size(inode); 622 struct ext2_dir_entry_2 * de; 623 int err; 624 void *kaddr; 625 626 if (!page) 627 return -ENOMEM; 628 629 err = ext2_prepare_chunk(page, 0, chunk_size); 630 if (err) { 631 unlock_page(page); 632 goto fail; 633 } 634 kaddr = kmap_local_page(page); 635 memset(kaddr, 0, chunk_size); 636 de = (struct ext2_dir_entry_2 *)kaddr; 637 de->name_len = 1; 638 de->rec_len = ext2_rec_len_to_disk(EXT2_DIR_REC_LEN(1)); 639 memcpy (de->name, ".\0\0", 4); 640 de->inode = cpu_to_le32(inode->i_ino); 641 ext2_set_de_type (de, inode); 642 643 de = (struct ext2_dir_entry_2 *)(kaddr + EXT2_DIR_REC_LEN(1)); 644 de->name_len = 2; 645 de->rec_len = ext2_rec_len_to_disk(chunk_size - EXT2_DIR_REC_LEN(1)); 646 de->inode = cpu_to_le32(parent->i_ino); 647 memcpy (de->name, "..\0", 4); 648 ext2_set_de_type (de, inode); 649 kunmap_local(kaddr); 650 ext2_commit_chunk(page, 0, chunk_size); 651 err = ext2_handle_dirsync(inode); 652fail: 653 put_page(page); 654 return err; 655} 656 657/* 658 * routine to check that the specified directory is empty (for rmdir) 659 */ 660int ext2_empty_dir (struct inode * inode) 661{ 662 struct page *page; 663 char *kaddr; 664 unsigned long i, npages = dir_pages(inode); 665 666 for (i = 0; i < npages; i++) { 667 ext2_dirent *de; 668 669 kaddr = ext2_get_page(inode, i, 0, &page); 670 if (IS_ERR(kaddr)) 671 return 0; 672 673 de = (ext2_dirent *)kaddr; 674 kaddr += ext2_last_byte(inode, i) - EXT2_DIR_REC_LEN(1); 675 676 while ((char *)de <= kaddr) { 677 if (de->rec_len == 0) { 678 ext2_error(inode->i_sb, __func__, 679 "zero-length directory entry"); 680 printk("kaddr=%p, de=%p\n", kaddr, de); 681 goto not_empty; 682 } 683 if (de->inode != 0) { 684 /* check for . and .. */ 685 if (de->name[0] != '.') 686 goto not_empty; 687 if (de->name_len > 2) 688 goto not_empty; 689 if (de->name_len < 2) { 690 if (de->inode != 691 cpu_to_le32(inode->i_ino)) 692 goto not_empty; 693 } else if (de->name[1] != '.') 694 goto not_empty; 695 } 696 de = ext2_next_entry(de); 697 } 698 ext2_put_page(page, kaddr); 699 } 700 return 1; 701 702not_empty: 703 ext2_put_page(page, kaddr); 704 return 0; 705} 706 707const struct file_operations ext2_dir_operations = { 708 .llseek = generic_file_llseek, 709 .read = generic_read_dir, 710 .iterate_shared = ext2_readdir, 711 .unlocked_ioctl = ext2_ioctl, 712#ifdef CONFIG_COMPAT 713 .compat_ioctl = ext2_compat_ioctl, 714#endif 715 .fsync = ext2_fsync, 716}; 717