1 /* 2 * linux/fs/ext4/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 * ext4 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 * Hash Tree Directory indexing (c) 2001 Daniel Phillips 21 * 22 */ 23 24 #include <linux/fs.h> 25 #include <linux/jbd2.h> 26 #include <linux/buffer_head.h> 27 #include <linux/slab.h> 28 #include <linux/rbtree.h> 29 #include "ext4.h" 30 31 static unsigned char ext4_filetype_table[] = { 32 DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK, DT_FIFO, DT_SOCK, DT_LNK 33 }; 34 35 static int ext4_dx_readdir(struct file *filp, 36 void *dirent, filldir_t filldir); 37 38 static unsigned char get_dtype(struct super_block *sb, int filetype) 39 { 40 if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FILETYPE) || 41 (filetype >= EXT4_FT_MAX)) 42 return DT_UNKNOWN; 43 44 return (ext4_filetype_table[filetype]); 45 } 46 47 /** 48 * Check if the given dir-inode refers to an htree-indexed directory 49 * (or a directory which chould potentially get coverted to use htree 50 * indexing). 51 * 52 * Return 1 if it is a dx dir, 0 if not 53 */ 54 static int is_dx_dir(struct inode *inode) 55 { 56 struct super_block *sb = inode->i_sb; 57 58 if (EXT4_HAS_COMPAT_FEATURE(inode->i_sb, 59 EXT4_FEATURE_COMPAT_DIR_INDEX) && 60 ((ext4_test_inode_flag(inode, EXT4_INODE_INDEX)) || 61 ((inode->i_size >> sb->s_blocksize_bits) == 1))) 62 return 1; 63 64 return 0; 65 } 66 67 /* 68 * Return 0 if the directory entry is OK, and 1 if there is a problem 69 * 70 * Note: this is the opposite of what ext2 and ext3 historically returned... 71 */ 72 int __ext4_check_dir_entry(const char *function, unsigned int line, 73 struct inode *dir, struct file *filp, 74 struct ext4_dir_entry_2 *de, 75 struct buffer_head *bh, 76 unsigned int offset) 77 { 78 const char *error_msg = NULL; 79 const int rlen = ext4_rec_len_from_disk(de->rec_len, 80 dir->i_sb->s_blocksize); 81 82 if (unlikely(rlen < EXT4_DIR_REC_LEN(1))) 83 error_msg = "rec_len is smaller than minimal"; 84 else if (unlikely(rlen % 4 != 0)) 85 error_msg = "rec_len % 4 != 0"; 86 else if (unlikely(rlen < EXT4_DIR_REC_LEN(de->name_len))) 87 error_msg = "rec_len is too small for name_len"; 88 else if (unlikely(((char *) de - bh->b_data) + rlen > 89 dir->i_sb->s_blocksize)) 90 error_msg = "directory entry across blocks"; 91 else if (unlikely(le32_to_cpu(de->inode) > 92 le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count))) 93 error_msg = "inode out of bounds"; 94 else 95 return 0; 96 97 if (filp) 98 ext4_error_file(filp, function, line, bh->b_blocknr, 99 "bad entry in directory: %s - offset=%u(%u), " 100 "inode=%u, rec_len=%d, name_len=%d", 101 error_msg, (unsigned) (offset % bh->b_size), 102 offset, le32_to_cpu(de->inode), 103 rlen, de->name_len); 104 else 105 ext4_error_inode(dir, function, line, bh->b_blocknr, 106 "bad entry in directory: %s - offset=%u(%u), " 107 "inode=%u, rec_len=%d, name_len=%d", 108 error_msg, (unsigned) (offset % bh->b_size), 109 offset, le32_to_cpu(de->inode), 110 rlen, de->name_len); 111 112 return 1; 113 } 114 115 static int ext4_readdir(struct file *filp, 116 void *dirent, filldir_t filldir) 117 { 118 int error = 0; 119 unsigned int offset; 120 int i, stored; 121 struct ext4_dir_entry_2 *de; 122 int err; 123 struct inode *inode = filp->f_path.dentry->d_inode; 124 struct super_block *sb = inode->i_sb; 125 int ret = 0; 126 int dir_has_error = 0; 127 128 if (is_dx_dir(inode)) { 129 err = ext4_dx_readdir(filp, dirent, filldir); 130 if (err != ERR_BAD_DX_DIR) { 131 ret = err; 132 goto out; 133 } 134 /* 135 * We don't set the inode dirty flag since it's not 136 * critical that it get flushed back to the disk. 137 */ 138 ext4_clear_inode_flag(filp->f_path.dentry->d_inode, 139 EXT4_INODE_INDEX); 140 } 141 stored = 0; 142 offset = filp->f_pos & (sb->s_blocksize - 1); 143 144 while (!error && !stored && filp->f_pos < inode->i_size) { 145 struct ext4_map_blocks map; 146 struct buffer_head *bh = NULL; 147 148 map.m_lblk = filp->f_pos >> EXT4_BLOCK_SIZE_BITS(sb); 149 map.m_len = 1; 150 err = ext4_map_blocks(NULL, inode, &map, 0); 151 if (err > 0) { 152 pgoff_t index = map.m_pblk >> 153 (PAGE_CACHE_SHIFT - inode->i_blkbits); 154 if (!ra_has_index(&filp->f_ra, index)) 155 page_cache_sync_readahead( 156 sb->s_bdev->bd_inode->i_mapping, 157 &filp->f_ra, filp, 158 index, 1); 159 filp->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT; 160 bh = ext4_bread(NULL, inode, map.m_lblk, 0, &err); 161 } 162 163 /* 164 * We ignore I/O errors on directories so users have a chance 165 * of recovering data when there's a bad sector 166 */ 167 if (!bh) { 168 if (!dir_has_error) { 169 EXT4_ERROR_FILE(filp, 0, 170 "directory contains a " 171 "hole at offset %llu", 172 (unsigned long long) filp->f_pos); 173 dir_has_error = 1; 174 } 175 /* corrupt size? Maybe no more blocks to read */ 176 if (filp->f_pos > inode->i_blocks << 9) 177 break; 178 filp->f_pos += sb->s_blocksize - offset; 179 continue; 180 } 181 182 revalidate: 183 /* If the dir block has changed since the last call to 184 * readdir(2), then we might be pointing to an invalid 185 * dirent right now. Scan from the start of the block 186 * to make sure. */ 187 if (filp->f_version != inode->i_version) { 188 for (i = 0; i < sb->s_blocksize && i < offset; ) { 189 de = (struct ext4_dir_entry_2 *) 190 (bh->b_data + i); 191 /* It's too expensive to do a full 192 * dirent test each time round this 193 * loop, but we do have to test at 194 * least that it is non-zero. A 195 * failure will be detected in the 196 * dirent test below. */ 197 if (ext4_rec_len_from_disk(de->rec_len, 198 sb->s_blocksize) < EXT4_DIR_REC_LEN(1)) 199 break; 200 i += ext4_rec_len_from_disk(de->rec_len, 201 sb->s_blocksize); 202 } 203 offset = i; 204 filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1)) 205 | offset; 206 filp->f_version = inode->i_version; 207 } 208 209 while (!error && filp->f_pos < inode->i_size 210 && offset < sb->s_blocksize) { 211 de = (struct ext4_dir_entry_2 *) (bh->b_data + offset); 212 if (ext4_check_dir_entry(inode, filp, de, 213 bh, offset)) { 214 /* 215 * On error, skip the f_pos to the next block 216 */ 217 filp->f_pos = (filp->f_pos | 218 (sb->s_blocksize - 1)) + 1; 219 brelse(bh); 220 ret = stored; 221 goto out; 222 } 223 offset += ext4_rec_len_from_disk(de->rec_len, 224 sb->s_blocksize); 225 if (le32_to_cpu(de->inode)) { 226 /* We might block in the next section 227 * if the data destination is 228 * currently swapped out. So, use a 229 * version stamp to detect whether or 230 * not the directory has been modified 231 * during the copy operation. 232 */ 233 u64 version = filp->f_version; 234 235 error = filldir(dirent, de->name, 236 de->name_len, 237 filp->f_pos, 238 le32_to_cpu(de->inode), 239 get_dtype(sb, de->file_type)); 240 if (error) 241 break; 242 if (version != filp->f_version) 243 goto revalidate; 244 stored++; 245 } 246 filp->f_pos += ext4_rec_len_from_disk(de->rec_len, 247 sb->s_blocksize); 248 } 249 offset = 0; 250 brelse(bh); 251 } 252 out: 253 return ret; 254 } 255 256 static inline int is_32bit_api(void) 257 { 258 #ifdef CONFIG_COMPAT 259 return is_compat_task(); 260 #else 261 return (BITS_PER_LONG == 32); 262 #endif 263 } 264 265 /* 266 * These functions convert from the major/minor hash to an f_pos 267 * value for dx directories 268 * 269 * Upper layer (for example NFS) should specify FMODE_32BITHASH or 270 * FMODE_64BITHASH explicitly. On the other hand, we allow ext4 to be mounted 271 * directly on both 32-bit and 64-bit nodes, under such case, neither 272 * FMODE_32BITHASH nor FMODE_64BITHASH is specified. 273 */ 274 static inline loff_t hash2pos(struct file *filp, __u32 major, __u32 minor) 275 { 276 if ((filp->f_mode & FMODE_32BITHASH) || 277 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) 278 return major >> 1; 279 else 280 return ((__u64)(major >> 1) << 32) | (__u64)minor; 281 } 282 283 static inline __u32 pos2maj_hash(struct file *filp, loff_t pos) 284 { 285 if ((filp->f_mode & FMODE_32BITHASH) || 286 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) 287 return (pos << 1) & 0xffffffff; 288 else 289 return ((pos >> 32) << 1) & 0xffffffff; 290 } 291 292 static inline __u32 pos2min_hash(struct file *filp, loff_t pos) 293 { 294 if ((filp->f_mode & FMODE_32BITHASH) || 295 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) 296 return 0; 297 else 298 return pos & 0xffffffff; 299 } 300 301 /* 302 * Return 32- or 64-bit end-of-file for dx directories 303 */ 304 static inline loff_t ext4_get_htree_eof(struct file *filp) 305 { 306 if ((filp->f_mode & FMODE_32BITHASH) || 307 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) 308 return EXT4_HTREE_EOF_32BIT; 309 else 310 return EXT4_HTREE_EOF_64BIT; 311 } 312 313 314 /* 315 * ext4_dir_llseek() based on generic_file_llseek() to handle both 316 * non-htree and htree directories, where the "offset" is in terms 317 * of the filename hash value instead of the byte offset. 318 * 319 * NOTE: offsets obtained *before* ext4_set_inode_flag(dir, EXT4_INODE_INDEX) 320 * will be invalid once the directory was converted into a dx directory 321 */ 322 loff_t ext4_dir_llseek(struct file *file, loff_t offset, int origin) 323 { 324 struct inode *inode = file->f_mapping->host; 325 loff_t ret = -EINVAL; 326 int dx_dir = is_dx_dir(inode); 327 328 mutex_lock(&inode->i_mutex); 329 330 /* NOTE: relative offsets with dx directories might not work 331 * as expected, as it is difficult to figure out the 332 * correct offset between dx hashes */ 333 334 switch (origin) { 335 case SEEK_END: 336 if (unlikely(offset > 0)) 337 goto out_err; /* not supported for directories */ 338 339 /* so only negative offsets are left, does that have a 340 * meaning for directories at all? */ 341 if (dx_dir) 342 offset += ext4_get_htree_eof(file); 343 else 344 offset += inode->i_size; 345 break; 346 case SEEK_CUR: 347 /* 348 * Here we special-case the lseek(fd, 0, SEEK_CUR) 349 * position-querying operation. Avoid rewriting the "same" 350 * f_pos value back to the file because a concurrent read(), 351 * write() or lseek() might have altered it 352 */ 353 if (offset == 0) { 354 offset = file->f_pos; 355 goto out_ok; 356 } 357 358 offset += file->f_pos; 359 break; 360 } 361 362 if (unlikely(offset < 0)) 363 goto out_err; 364 365 if (!dx_dir) { 366 if (offset > inode->i_sb->s_maxbytes) 367 goto out_err; 368 } else if (offset > ext4_get_htree_eof(file)) 369 goto out_err; 370 371 /* Special lock needed here? */ 372 if (offset != file->f_pos) { 373 file->f_pos = offset; 374 file->f_version = 0; 375 } 376 377 out_ok: 378 ret = offset; 379 out_err: 380 mutex_unlock(&inode->i_mutex); 381 382 return ret; 383 } 384 385 /* 386 * This structure holds the nodes of the red-black tree used to store 387 * the directory entry in hash order. 388 */ 389 struct fname { 390 __u32 hash; 391 __u32 minor_hash; 392 struct rb_node rb_hash; 393 struct fname *next; 394 __u32 inode; 395 __u8 name_len; 396 __u8 file_type; 397 char name[0]; 398 }; 399 400 /* 401 * This functoin implements a non-recursive way of freeing all of the 402 * nodes in the red-black tree. 403 */ 404 static void free_rb_tree_fname(struct rb_root *root) 405 { 406 struct rb_node *n = root->rb_node; 407 struct rb_node *parent; 408 struct fname *fname; 409 410 while (n) { 411 /* Do the node's children first */ 412 if (n->rb_left) { 413 n = n->rb_left; 414 continue; 415 } 416 if (n->rb_right) { 417 n = n->rb_right; 418 continue; 419 } 420 /* 421 * The node has no children; free it, and then zero 422 * out parent's link to it. Finally go to the 423 * beginning of the loop and try to free the parent 424 * node. 425 */ 426 parent = rb_parent(n); 427 fname = rb_entry(n, struct fname, rb_hash); 428 while (fname) { 429 struct fname *old = fname; 430 fname = fname->next; 431 kfree(old); 432 } 433 if (!parent) 434 *root = RB_ROOT; 435 else if (parent->rb_left == n) 436 parent->rb_left = NULL; 437 else if (parent->rb_right == n) 438 parent->rb_right = NULL; 439 n = parent; 440 } 441 } 442 443 444 static struct dir_private_info *ext4_htree_create_dir_info(struct file *filp, 445 loff_t pos) 446 { 447 struct dir_private_info *p; 448 449 p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL); 450 if (!p) 451 return NULL; 452 p->curr_hash = pos2maj_hash(filp, pos); 453 p->curr_minor_hash = pos2min_hash(filp, pos); 454 return p; 455 } 456 457 void ext4_htree_free_dir_info(struct dir_private_info *p) 458 { 459 free_rb_tree_fname(&p->root); 460 kfree(p); 461 } 462 463 /* 464 * Given a directory entry, enter it into the fname rb tree. 465 */ 466 int ext4_htree_store_dirent(struct file *dir_file, __u32 hash, 467 __u32 minor_hash, 468 struct ext4_dir_entry_2 *dirent) 469 { 470 struct rb_node **p, *parent = NULL; 471 struct fname *fname, *new_fn; 472 struct dir_private_info *info; 473 int len; 474 475 info = dir_file->private_data; 476 p = &info->root.rb_node; 477 478 /* Create and allocate the fname structure */ 479 len = sizeof(struct fname) + dirent->name_len + 1; 480 new_fn = kzalloc(len, GFP_KERNEL); 481 if (!new_fn) 482 return -ENOMEM; 483 new_fn->hash = hash; 484 new_fn->minor_hash = minor_hash; 485 new_fn->inode = le32_to_cpu(dirent->inode); 486 new_fn->name_len = dirent->name_len; 487 new_fn->file_type = dirent->file_type; 488 memcpy(new_fn->name, dirent->name, dirent->name_len); 489 new_fn->name[dirent->name_len] = 0; 490 491 while (*p) { 492 parent = *p; 493 fname = rb_entry(parent, struct fname, rb_hash); 494 495 /* 496 * If the hash and minor hash match up, then we put 497 * them on a linked list. This rarely happens... 498 */ 499 if ((new_fn->hash == fname->hash) && 500 (new_fn->minor_hash == fname->minor_hash)) { 501 new_fn->next = fname->next; 502 fname->next = new_fn; 503 return 0; 504 } 505 506 if (new_fn->hash < fname->hash) 507 p = &(*p)->rb_left; 508 else if (new_fn->hash > fname->hash) 509 p = &(*p)->rb_right; 510 else if (new_fn->minor_hash < fname->minor_hash) 511 p = &(*p)->rb_left; 512 else /* if (new_fn->minor_hash > fname->minor_hash) */ 513 p = &(*p)->rb_right; 514 } 515 516 rb_link_node(&new_fn->rb_hash, parent, p); 517 rb_insert_color(&new_fn->rb_hash, &info->root); 518 return 0; 519 } 520 521 522 523 /* 524 * This is a helper function for ext4_dx_readdir. It calls filldir 525 * for all entres on the fname linked list. (Normally there is only 526 * one entry on the linked list, unless there are 62 bit hash collisions.) 527 */ 528 static int call_filldir(struct file *filp, void *dirent, 529 filldir_t filldir, struct fname *fname) 530 { 531 struct dir_private_info *info = filp->private_data; 532 loff_t curr_pos; 533 struct inode *inode = filp->f_path.dentry->d_inode; 534 struct super_block *sb; 535 int error; 536 537 sb = inode->i_sb; 538 539 if (!fname) { 540 ext4_msg(sb, KERN_ERR, "%s:%d: inode #%lu: comm %s: " 541 "called with null fname?!?", __func__, __LINE__, 542 inode->i_ino, current->comm); 543 return 0; 544 } 545 curr_pos = hash2pos(filp, fname->hash, fname->minor_hash); 546 while (fname) { 547 error = filldir(dirent, fname->name, 548 fname->name_len, curr_pos, 549 fname->inode, 550 get_dtype(sb, fname->file_type)); 551 if (error) { 552 filp->f_pos = curr_pos; 553 info->extra_fname = fname; 554 return error; 555 } 556 fname = fname->next; 557 } 558 return 0; 559 } 560 561 static int ext4_dx_readdir(struct file *filp, 562 void *dirent, filldir_t filldir) 563 { 564 struct dir_private_info *info = filp->private_data; 565 struct inode *inode = filp->f_path.dentry->d_inode; 566 struct fname *fname; 567 int ret; 568 569 if (!info) { 570 info = ext4_htree_create_dir_info(filp, filp->f_pos); 571 if (!info) 572 return -ENOMEM; 573 filp->private_data = info; 574 } 575 576 if (filp->f_pos == ext4_get_htree_eof(filp)) 577 return 0; /* EOF */ 578 579 /* Some one has messed with f_pos; reset the world */ 580 if (info->last_pos != filp->f_pos) { 581 free_rb_tree_fname(&info->root); 582 info->curr_node = NULL; 583 info->extra_fname = NULL; 584 info->curr_hash = pos2maj_hash(filp, filp->f_pos); 585 info->curr_minor_hash = pos2min_hash(filp, filp->f_pos); 586 } 587 588 /* 589 * If there are any leftover names on the hash collision 590 * chain, return them first. 591 */ 592 if (info->extra_fname) { 593 if (call_filldir(filp, dirent, filldir, info->extra_fname)) 594 goto finished; 595 info->extra_fname = NULL; 596 goto next_node; 597 } else if (!info->curr_node) 598 info->curr_node = rb_first(&info->root); 599 600 while (1) { 601 /* 602 * Fill the rbtree if we have no more entries, 603 * or the inode has changed since we last read in the 604 * cached entries. 605 */ 606 if ((!info->curr_node) || 607 (filp->f_version != inode->i_version)) { 608 info->curr_node = NULL; 609 free_rb_tree_fname(&info->root); 610 filp->f_version = inode->i_version; 611 ret = ext4_htree_fill_tree(filp, info->curr_hash, 612 info->curr_minor_hash, 613 &info->next_hash); 614 if (ret < 0) 615 return ret; 616 if (ret == 0) { 617 filp->f_pos = ext4_get_htree_eof(filp); 618 break; 619 } 620 info->curr_node = rb_first(&info->root); 621 } 622 623 fname = rb_entry(info->curr_node, struct fname, rb_hash); 624 info->curr_hash = fname->hash; 625 info->curr_minor_hash = fname->minor_hash; 626 if (call_filldir(filp, dirent, filldir, fname)) 627 break; 628 next_node: 629 info->curr_node = rb_next(info->curr_node); 630 if (info->curr_node) { 631 fname = rb_entry(info->curr_node, struct fname, 632 rb_hash); 633 info->curr_hash = fname->hash; 634 info->curr_minor_hash = fname->minor_hash; 635 } else { 636 if (info->next_hash == ~0) { 637 filp->f_pos = ext4_get_htree_eof(filp); 638 break; 639 } 640 info->curr_hash = info->next_hash; 641 info->curr_minor_hash = 0; 642 } 643 } 644 finished: 645 info->last_pos = filp->f_pos; 646 return 0; 647 } 648 649 static int ext4_release_dir(struct inode *inode, struct file *filp) 650 { 651 if (filp->private_data) 652 ext4_htree_free_dir_info(filp->private_data); 653 654 return 0; 655 } 656 657 const struct file_operations ext4_dir_operations = { 658 .llseek = ext4_dir_llseek, 659 .read = generic_read_dir, 660 .readdir = ext4_readdir, 661 .unlocked_ioctl = ext4_ioctl, 662 #ifdef CONFIG_COMPAT 663 .compat_ioctl = ext4_compat_ioctl, 664 #endif 665 .fsync = ext4_sync_file, 666 .release = ext4_release_dir, 667 }; 668