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 wait_on_page_locked(page); 165 kmap(page); 166 if (!PageUptodate(page)) 167 goto fail; 168 if (!PageChecked(page)) 169 ext2_check_page(page); 170 if (PageError(page)) 171 goto fail; 172 } 173 return page; 174 175 fail: 176 ext2_put_page(page); 177 return ERR_PTR(-EIO); 178 } 179 180 /* 181 * NOTE! unlike strncmp, ext2_match returns 1 for success, 0 for failure. 182 * 183 * len <= EXT2_NAME_LEN and de != NULL are guaranteed by caller. 184 */ 185 static inline int ext2_match (int len, const char * const name, 186 struct ext2_dir_entry_2 * de) 187 { 188 if (len != de->name_len) 189 return 0; 190 if (!de->inode) 191 return 0; 192 return !memcmp(name, de->name, len); 193 } 194 195 /* 196 * p is at least 6 bytes before the end of page 197 */ 198 static inline ext2_dirent *ext2_next_entry(ext2_dirent *p) 199 { 200 return (ext2_dirent *)((char*)p + le16_to_cpu(p->rec_len)); 201 } 202 203 static inline unsigned 204 ext2_validate_entry(char *base, unsigned offset, unsigned mask) 205 { 206 ext2_dirent *de = (ext2_dirent*)(base + offset); 207 ext2_dirent *p = (ext2_dirent*)(base + (offset&mask)); 208 while ((char*)p < (char*)de) { 209 if (p->rec_len == 0) 210 break; 211 p = ext2_next_entry(p); 212 } 213 return (char *)p - base; 214 } 215 216 static unsigned char ext2_filetype_table[EXT2_FT_MAX] = { 217 [EXT2_FT_UNKNOWN] = DT_UNKNOWN, 218 [EXT2_FT_REG_FILE] = DT_REG, 219 [EXT2_FT_DIR] = DT_DIR, 220 [EXT2_FT_CHRDEV] = DT_CHR, 221 [EXT2_FT_BLKDEV] = DT_BLK, 222 [EXT2_FT_FIFO] = DT_FIFO, 223 [EXT2_FT_SOCK] = DT_SOCK, 224 [EXT2_FT_SYMLINK] = DT_LNK, 225 }; 226 227 #define S_SHIFT 12 228 static unsigned char ext2_type_by_mode[S_IFMT >> S_SHIFT] = { 229 [S_IFREG >> S_SHIFT] = EXT2_FT_REG_FILE, 230 [S_IFDIR >> S_SHIFT] = EXT2_FT_DIR, 231 [S_IFCHR >> S_SHIFT] = EXT2_FT_CHRDEV, 232 [S_IFBLK >> S_SHIFT] = EXT2_FT_BLKDEV, 233 [S_IFIFO >> S_SHIFT] = EXT2_FT_FIFO, 234 [S_IFSOCK >> S_SHIFT] = EXT2_FT_SOCK, 235 [S_IFLNK >> S_SHIFT] = EXT2_FT_SYMLINK, 236 }; 237 238 static inline void ext2_set_de_type(ext2_dirent *de, struct inode *inode) 239 { 240 mode_t mode = inode->i_mode; 241 if (EXT2_HAS_INCOMPAT_FEATURE(inode->i_sb, EXT2_FEATURE_INCOMPAT_FILETYPE)) 242 de->file_type = ext2_type_by_mode[(mode & S_IFMT)>>S_SHIFT]; 243 else 244 de->file_type = 0; 245 } 246 247 static int 248 ext2_readdir (struct file * filp, void * dirent, filldir_t filldir) 249 { 250 loff_t pos = filp->f_pos; 251 struct inode *inode = filp->f_path.dentry->d_inode; 252 struct super_block *sb = inode->i_sb; 253 unsigned int offset = pos & ~PAGE_CACHE_MASK; 254 unsigned long n = pos >> PAGE_CACHE_SHIFT; 255 unsigned long npages = dir_pages(inode); 256 unsigned chunk_mask = ~(ext2_chunk_size(inode)-1); 257 unsigned char *types = NULL; 258 int need_revalidate = filp->f_version != inode->i_version; 259 260 if (pos > inode->i_size - EXT2_DIR_REC_LEN(1)) 261 return 0; 262 263 if (EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_FILETYPE)) 264 types = ext2_filetype_table; 265 266 for ( ; n < npages; n++, offset = 0) { 267 char *kaddr, *limit; 268 ext2_dirent *de; 269 struct page *page = ext2_get_page(inode, n); 270 271 if (IS_ERR(page)) { 272 ext2_error(sb, __FUNCTION__, 273 "bad page in #%lu", 274 inode->i_ino); 275 filp->f_pos += PAGE_CACHE_SIZE - offset; 276 return -EIO; 277 } 278 kaddr = page_address(page); 279 if (unlikely(need_revalidate)) { 280 if (offset) { 281 offset = ext2_validate_entry(kaddr, offset, chunk_mask); 282 filp->f_pos = (n<<PAGE_CACHE_SHIFT) + offset; 283 } 284 filp->f_version = inode->i_version; 285 need_revalidate = 0; 286 } 287 de = (ext2_dirent *)(kaddr+offset); 288 limit = kaddr + ext2_last_byte(inode, n) - EXT2_DIR_REC_LEN(1); 289 for ( ;(char*)de <= limit; de = ext2_next_entry(de)) { 290 if (de->rec_len == 0) { 291 ext2_error(sb, __FUNCTION__, 292 "zero-length directory entry"); 293 ext2_put_page(page); 294 return -EIO; 295 } 296 if (de->inode) { 297 int over; 298 unsigned char d_type = DT_UNKNOWN; 299 300 if (types && de->file_type < EXT2_FT_MAX) 301 d_type = types[de->file_type]; 302 303 offset = (char *)de - kaddr; 304 over = filldir(dirent, de->name, de->name_len, 305 (n<<PAGE_CACHE_SHIFT) | offset, 306 le32_to_cpu(de->inode), d_type); 307 if (over) { 308 ext2_put_page(page); 309 return 0; 310 } 311 } 312 filp->f_pos += le16_to_cpu(de->rec_len); 313 } 314 ext2_put_page(page); 315 } 316 return 0; 317 } 318 319 /* 320 * ext2_find_entry() 321 * 322 * finds an entry in the specified directory with the wanted name. It 323 * returns the page in which the entry was found, and the entry itself 324 * (as a parameter - res_dir). Page is returned mapped and unlocked. 325 * Entry is guaranteed to be valid. 326 */ 327 struct ext2_dir_entry_2 * ext2_find_entry (struct inode * dir, 328 struct dentry *dentry, struct page ** res_page) 329 { 330 const char *name = dentry->d_name.name; 331 int namelen = dentry->d_name.len; 332 unsigned reclen = EXT2_DIR_REC_LEN(namelen); 333 unsigned long start, n; 334 unsigned long npages = dir_pages(dir); 335 struct page *page = NULL; 336 struct ext2_inode_info *ei = EXT2_I(dir); 337 ext2_dirent * de; 338 339 if (npages == 0) 340 goto out; 341 342 /* OFFSET_CACHE */ 343 *res_page = NULL; 344 345 start = ei->i_dir_start_lookup; 346 if (start >= npages) 347 start = 0; 348 n = start; 349 do { 350 char *kaddr; 351 page = ext2_get_page(dir, n); 352 if (!IS_ERR(page)) { 353 kaddr = page_address(page); 354 de = (ext2_dirent *) kaddr; 355 kaddr += ext2_last_byte(dir, n) - reclen; 356 while ((char *) de <= kaddr) { 357 if (de->rec_len == 0) { 358 ext2_error(dir->i_sb, __FUNCTION__, 359 "zero-length directory entry"); 360 ext2_put_page(page); 361 goto out; 362 } 363 if (ext2_match (namelen, name, de)) 364 goto found; 365 de = ext2_next_entry(de); 366 } 367 ext2_put_page(page); 368 } 369 if (++n >= npages) 370 n = 0; 371 /* next page is past the blocks we've got */ 372 if (unlikely(n > (dir->i_blocks >> (PAGE_CACHE_SHIFT - 9)))) { 373 ext2_error(dir->i_sb, __FUNCTION__, 374 "dir %lu size %lld exceeds block count %llu", 375 dir->i_ino, dir->i_size, 376 (unsigned long long)dir->i_blocks); 377 goto out; 378 } 379 } while (n != start); 380 out: 381 return NULL; 382 383 found: 384 *res_page = page; 385 ei->i_dir_start_lookup = n; 386 return de; 387 } 388 389 struct ext2_dir_entry_2 * ext2_dotdot (struct inode *dir, struct page **p) 390 { 391 struct page *page = ext2_get_page(dir, 0); 392 ext2_dirent *de = NULL; 393 394 if (!IS_ERR(page)) { 395 de = ext2_next_entry((ext2_dirent *) page_address(page)); 396 *p = page; 397 } 398 return de; 399 } 400 401 ino_t ext2_inode_by_name(struct inode * dir, struct dentry *dentry) 402 { 403 ino_t res = 0; 404 struct ext2_dir_entry_2 * de; 405 struct page *page; 406 407 de = ext2_find_entry (dir, dentry, &page); 408 if (de) { 409 res = le32_to_cpu(de->inode); 410 ext2_put_page(page); 411 } 412 return res; 413 } 414 415 /* Releases the page */ 416 void ext2_set_link(struct inode *dir, struct ext2_dir_entry_2 *de, 417 struct page *page, struct inode *inode) 418 { 419 unsigned from = (char *) de - (char *) page_address(page); 420 unsigned to = from + le16_to_cpu(de->rec_len); 421 int err; 422 423 lock_page(page); 424 err = page->mapping->a_ops->prepare_write(NULL, page, from, to); 425 BUG_ON(err); 426 de->inode = cpu_to_le32(inode->i_ino); 427 ext2_set_de_type (de, inode); 428 err = ext2_commit_chunk(page, from, to); 429 ext2_put_page(page); 430 dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC; 431 EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL; 432 mark_inode_dirty(dir); 433 } 434 435 /* 436 * Parent is locked. 437 */ 438 int ext2_add_link (struct dentry *dentry, struct inode *inode) 439 { 440 struct inode *dir = dentry->d_parent->d_inode; 441 const char *name = dentry->d_name.name; 442 int namelen = dentry->d_name.len; 443 unsigned chunk_size = ext2_chunk_size(dir); 444 unsigned reclen = EXT2_DIR_REC_LEN(namelen); 445 unsigned short rec_len, name_len; 446 struct page *page = NULL; 447 ext2_dirent * de; 448 unsigned long npages = dir_pages(dir); 449 unsigned long n; 450 char *kaddr; 451 unsigned from, to; 452 int err; 453 454 /* 455 * We take care of directory expansion in the same loop. 456 * This code plays outside i_size, so it locks the page 457 * to protect that region. 458 */ 459 for (n = 0; n <= npages; n++) { 460 char *dir_end; 461 462 page = ext2_get_page(dir, n); 463 err = PTR_ERR(page); 464 if (IS_ERR(page)) 465 goto out; 466 lock_page(page); 467 kaddr = page_address(page); 468 dir_end = kaddr + ext2_last_byte(dir, n); 469 de = (ext2_dirent *)kaddr; 470 kaddr += PAGE_CACHE_SIZE - reclen; 471 while ((char *)de <= kaddr) { 472 if ((char *)de == dir_end) { 473 /* We hit i_size */ 474 name_len = 0; 475 rec_len = chunk_size; 476 de->rec_len = cpu_to_le16(chunk_size); 477 de->inode = 0; 478 goto got_it; 479 } 480 if (de->rec_len == 0) { 481 ext2_error(dir->i_sb, __FUNCTION__, 482 "zero-length directory entry"); 483 err = -EIO; 484 goto out_unlock; 485 } 486 err = -EEXIST; 487 if (ext2_match (namelen, name, de)) 488 goto out_unlock; 489 name_len = EXT2_DIR_REC_LEN(de->name_len); 490 rec_len = le16_to_cpu(de->rec_len); 491 if (!de->inode && rec_len >= reclen) 492 goto got_it; 493 if (rec_len >= name_len + reclen) 494 goto got_it; 495 de = (ext2_dirent *) ((char *) de + rec_len); 496 } 497 unlock_page(page); 498 ext2_put_page(page); 499 } 500 BUG(); 501 return -EINVAL; 502 503 got_it: 504 from = (char*)de - (char*)page_address(page); 505 to = from + rec_len; 506 err = page->mapping->a_ops->prepare_write(NULL, page, from, to); 507 if (err) 508 goto out_unlock; 509 if (de->inode) { 510 ext2_dirent *de1 = (ext2_dirent *) ((char *) de + name_len); 511 de1->rec_len = cpu_to_le16(rec_len - name_len); 512 de->rec_len = cpu_to_le16(name_len); 513 de = de1; 514 } 515 de->name_len = namelen; 516 memcpy (de->name, name, namelen); 517 de->inode = cpu_to_le32(inode->i_ino); 518 ext2_set_de_type (de, inode); 519 err = ext2_commit_chunk(page, from, to); 520 dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC; 521 EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL; 522 mark_inode_dirty(dir); 523 /* OFFSET_CACHE */ 524 out_put: 525 ext2_put_page(page); 526 out: 527 return err; 528 out_unlock: 529 unlock_page(page); 530 goto out_put; 531 } 532 533 /* 534 * ext2_delete_entry deletes a directory entry by merging it with the 535 * previous entry. Page is up-to-date. Releases the page. 536 */ 537 int ext2_delete_entry (struct ext2_dir_entry_2 * dir, struct page * page ) 538 { 539 struct address_space *mapping = page->mapping; 540 struct inode *inode = mapping->host; 541 char *kaddr = page_address(page); 542 unsigned from = ((char*)dir - kaddr) & ~(ext2_chunk_size(inode)-1); 543 unsigned to = ((char*)dir - kaddr) + le16_to_cpu(dir->rec_len); 544 ext2_dirent * pde = NULL; 545 ext2_dirent * de = (ext2_dirent *) (kaddr + from); 546 int err; 547 548 while ((char*)de < (char*)dir) { 549 if (de->rec_len == 0) { 550 ext2_error(inode->i_sb, __FUNCTION__, 551 "zero-length directory entry"); 552 err = -EIO; 553 goto out; 554 } 555 pde = de; 556 de = ext2_next_entry(de); 557 } 558 if (pde) 559 from = (char*)pde - (char*)page_address(page); 560 lock_page(page); 561 err = mapping->a_ops->prepare_write(NULL, page, from, to); 562 BUG_ON(err); 563 if (pde) 564 pde->rec_len = cpu_to_le16(to-from); 565 dir->inode = 0; 566 err = ext2_commit_chunk(page, from, to); 567 inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC; 568 EXT2_I(inode)->i_flags &= ~EXT2_BTREE_FL; 569 mark_inode_dirty(inode); 570 out: 571 ext2_put_page(page); 572 return err; 573 } 574 575 /* 576 * Set the first fragment of directory. 577 */ 578 int ext2_make_empty(struct inode *inode, struct inode *parent) 579 { 580 struct address_space *mapping = inode->i_mapping; 581 struct page *page = grab_cache_page(mapping, 0); 582 unsigned chunk_size = ext2_chunk_size(inode); 583 struct ext2_dir_entry_2 * de; 584 int err; 585 void *kaddr; 586 587 if (!page) 588 return -ENOMEM; 589 err = mapping->a_ops->prepare_write(NULL, page, 0, chunk_size); 590 if (err) { 591 unlock_page(page); 592 goto fail; 593 } 594 kaddr = kmap_atomic(page, KM_USER0); 595 memset(kaddr, 0, chunk_size); 596 de = (struct ext2_dir_entry_2 *)kaddr; 597 de->name_len = 1; 598 de->rec_len = cpu_to_le16(EXT2_DIR_REC_LEN(1)); 599 memcpy (de->name, ".\0\0", 4); 600 de->inode = cpu_to_le32(inode->i_ino); 601 ext2_set_de_type (de, inode); 602 603 de = (struct ext2_dir_entry_2 *)(kaddr + EXT2_DIR_REC_LEN(1)); 604 de->name_len = 2; 605 de->rec_len = cpu_to_le16(chunk_size - EXT2_DIR_REC_LEN(1)); 606 de->inode = cpu_to_le32(parent->i_ino); 607 memcpy (de->name, "..\0", 4); 608 ext2_set_de_type (de, inode); 609 kunmap_atomic(kaddr, KM_USER0); 610 err = ext2_commit_chunk(page, 0, chunk_size); 611 fail: 612 page_cache_release(page); 613 return err; 614 } 615 616 /* 617 * routine to check that the specified directory is empty (for rmdir) 618 */ 619 int ext2_empty_dir (struct inode * inode) 620 { 621 struct page *page = NULL; 622 unsigned long i, npages = dir_pages(inode); 623 624 for (i = 0; i < npages; i++) { 625 char *kaddr; 626 ext2_dirent * de; 627 page = ext2_get_page(inode, i); 628 629 if (IS_ERR(page)) 630 continue; 631 632 kaddr = page_address(page); 633 de = (ext2_dirent *)kaddr; 634 kaddr += ext2_last_byte(inode, i) - EXT2_DIR_REC_LEN(1); 635 636 while ((char *)de <= kaddr) { 637 if (de->rec_len == 0) { 638 ext2_error(inode->i_sb, __FUNCTION__, 639 "zero-length directory entry"); 640 printk("kaddr=%p, de=%p\n", kaddr, de); 641 goto not_empty; 642 } 643 if (de->inode != 0) { 644 /* check for . and .. */ 645 if (de->name[0] != '.') 646 goto not_empty; 647 if (de->name_len > 2) 648 goto not_empty; 649 if (de->name_len < 2) { 650 if (de->inode != 651 cpu_to_le32(inode->i_ino)) 652 goto not_empty; 653 } else if (de->name[1] != '.') 654 goto not_empty; 655 } 656 de = ext2_next_entry(de); 657 } 658 ext2_put_page(page); 659 } 660 return 1; 661 662 not_empty: 663 ext2_put_page(page); 664 return 0; 665 } 666 667 const struct file_operations ext2_dir_operations = { 668 .llseek = generic_file_llseek, 669 .read = generic_read_dir, 670 .readdir = ext2_readdir, 671 .ioctl = ext2_ioctl, 672 #ifdef CONFIG_COMPAT 673 .compat_ioctl = ext2_compat_ioctl, 674 #endif 675 .fsync = ext2_sync_file, 676 }; 677