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 /* Check the checksum */ 183 if (!buffer_verified(bh) && 184 !ext4_dirent_csum_verify(inode, 185 (struct ext4_dir_entry *)bh->b_data)) { 186 EXT4_ERROR_FILE(filp, 0, "directory fails checksum " 187 "at offset %llu", 188 (unsigned long long)filp->f_pos); 189 filp->f_pos += sb->s_blocksize - offset; 190 continue; 191 } 192 set_buffer_verified(bh); 193 194 revalidate: 195 /* If the dir block has changed since the last call to 196 * readdir(2), then we might be pointing to an invalid 197 * dirent right now. Scan from the start of the block 198 * to make sure. */ 199 if (filp->f_version != inode->i_version) { 200 for (i = 0; i < sb->s_blocksize && i < offset; ) { 201 de = (struct ext4_dir_entry_2 *) 202 (bh->b_data + i); 203 /* It's too expensive to do a full 204 * dirent test each time round this 205 * loop, but we do have to test at 206 * least that it is non-zero. A 207 * failure will be detected in the 208 * dirent test below. */ 209 if (ext4_rec_len_from_disk(de->rec_len, 210 sb->s_blocksize) < EXT4_DIR_REC_LEN(1)) 211 break; 212 i += ext4_rec_len_from_disk(de->rec_len, 213 sb->s_blocksize); 214 } 215 offset = i; 216 filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1)) 217 | offset; 218 filp->f_version = inode->i_version; 219 } 220 221 while (!error && filp->f_pos < inode->i_size 222 && offset < sb->s_blocksize) { 223 de = (struct ext4_dir_entry_2 *) (bh->b_data + offset); 224 if (ext4_check_dir_entry(inode, filp, de, 225 bh, offset)) { 226 /* 227 * On error, skip the f_pos to the next block 228 */ 229 filp->f_pos = (filp->f_pos | 230 (sb->s_blocksize - 1)) + 1; 231 brelse(bh); 232 ret = stored; 233 goto out; 234 } 235 offset += ext4_rec_len_from_disk(de->rec_len, 236 sb->s_blocksize); 237 if (le32_to_cpu(de->inode)) { 238 /* We might block in the next section 239 * if the data destination is 240 * currently swapped out. So, use a 241 * version stamp to detect whether or 242 * not the directory has been modified 243 * during the copy operation. 244 */ 245 u64 version = filp->f_version; 246 247 error = filldir(dirent, de->name, 248 de->name_len, 249 filp->f_pos, 250 le32_to_cpu(de->inode), 251 get_dtype(sb, de->file_type)); 252 if (error) 253 break; 254 if (version != filp->f_version) 255 goto revalidate; 256 stored++; 257 } 258 filp->f_pos += ext4_rec_len_from_disk(de->rec_len, 259 sb->s_blocksize); 260 } 261 offset = 0; 262 brelse(bh); 263 } 264 out: 265 return ret; 266 } 267 268 static inline int is_32bit_api(void) 269 { 270 #ifdef CONFIG_COMPAT 271 return is_compat_task(); 272 #else 273 return (BITS_PER_LONG == 32); 274 #endif 275 } 276 277 /* 278 * These functions convert from the major/minor hash to an f_pos 279 * value for dx directories 280 * 281 * Upper layer (for example NFS) should specify FMODE_32BITHASH or 282 * FMODE_64BITHASH explicitly. On the other hand, we allow ext4 to be mounted 283 * directly on both 32-bit and 64-bit nodes, under such case, neither 284 * FMODE_32BITHASH nor FMODE_64BITHASH is specified. 285 */ 286 static inline loff_t hash2pos(struct file *filp, __u32 major, __u32 minor) 287 { 288 if ((filp->f_mode & FMODE_32BITHASH) || 289 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) 290 return major >> 1; 291 else 292 return ((__u64)(major >> 1) << 32) | (__u64)minor; 293 } 294 295 static inline __u32 pos2maj_hash(struct file *filp, loff_t pos) 296 { 297 if ((filp->f_mode & FMODE_32BITHASH) || 298 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) 299 return (pos << 1) & 0xffffffff; 300 else 301 return ((pos >> 32) << 1) & 0xffffffff; 302 } 303 304 static inline __u32 pos2min_hash(struct file *filp, loff_t pos) 305 { 306 if ((filp->f_mode & FMODE_32BITHASH) || 307 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) 308 return 0; 309 else 310 return pos & 0xffffffff; 311 } 312 313 /* 314 * Return 32- or 64-bit end-of-file for dx directories 315 */ 316 static inline loff_t ext4_get_htree_eof(struct file *filp) 317 { 318 if ((filp->f_mode & FMODE_32BITHASH) || 319 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) 320 return EXT4_HTREE_EOF_32BIT; 321 else 322 return EXT4_HTREE_EOF_64BIT; 323 } 324 325 326 /* 327 * ext4_dir_llseek() calls generic_file_llseek_size to handle htree 328 * directories, where the "offset" is in terms of the filename hash 329 * value instead of the byte offset. 330 * 331 * Because we may return a 64-bit hash that is well beyond offset limits, 332 * we need to pass the max hash as the maximum allowable offset in 333 * the htree directory case. 334 * 335 * For non-htree, ext4_llseek already chooses the proper max offset. 336 */ 337 loff_t ext4_dir_llseek(struct file *file, loff_t offset, int origin) 338 { 339 struct inode *inode = file->f_mapping->host; 340 int dx_dir = is_dx_dir(inode); 341 loff_t htree_max = ext4_get_htree_eof(file); 342 343 if (likely(dx_dir)) 344 return generic_file_llseek_size(file, offset, origin, 345 htree_max, htree_max); 346 else 347 return ext4_llseek(file, offset, origin); 348 } 349 350 /* 351 * This structure holds the nodes of the red-black tree used to store 352 * the directory entry in hash order. 353 */ 354 struct fname { 355 __u32 hash; 356 __u32 minor_hash; 357 struct rb_node rb_hash; 358 struct fname *next; 359 __u32 inode; 360 __u8 name_len; 361 __u8 file_type; 362 char name[0]; 363 }; 364 365 /* 366 * This functoin implements a non-recursive way of freeing all of the 367 * nodes in the red-black tree. 368 */ 369 static void free_rb_tree_fname(struct rb_root *root) 370 { 371 struct rb_node *n = root->rb_node; 372 struct rb_node *parent; 373 struct fname *fname; 374 375 while (n) { 376 /* Do the node's children first */ 377 if (n->rb_left) { 378 n = n->rb_left; 379 continue; 380 } 381 if (n->rb_right) { 382 n = n->rb_right; 383 continue; 384 } 385 /* 386 * The node has no children; free it, and then zero 387 * out parent's link to it. Finally go to the 388 * beginning of the loop and try to free the parent 389 * node. 390 */ 391 parent = rb_parent(n); 392 fname = rb_entry(n, struct fname, rb_hash); 393 while (fname) { 394 struct fname *old = fname; 395 fname = fname->next; 396 kfree(old); 397 } 398 if (!parent) 399 *root = RB_ROOT; 400 else if (parent->rb_left == n) 401 parent->rb_left = NULL; 402 else if (parent->rb_right == n) 403 parent->rb_right = NULL; 404 n = parent; 405 } 406 } 407 408 409 static struct dir_private_info *ext4_htree_create_dir_info(struct file *filp, 410 loff_t pos) 411 { 412 struct dir_private_info *p; 413 414 p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL); 415 if (!p) 416 return NULL; 417 p->curr_hash = pos2maj_hash(filp, pos); 418 p->curr_minor_hash = pos2min_hash(filp, pos); 419 return p; 420 } 421 422 void ext4_htree_free_dir_info(struct dir_private_info *p) 423 { 424 free_rb_tree_fname(&p->root); 425 kfree(p); 426 } 427 428 /* 429 * Given a directory entry, enter it into the fname rb tree. 430 */ 431 int ext4_htree_store_dirent(struct file *dir_file, __u32 hash, 432 __u32 minor_hash, 433 struct ext4_dir_entry_2 *dirent) 434 { 435 struct rb_node **p, *parent = NULL; 436 struct fname *fname, *new_fn; 437 struct dir_private_info *info; 438 int len; 439 440 info = dir_file->private_data; 441 p = &info->root.rb_node; 442 443 /* Create and allocate the fname structure */ 444 len = sizeof(struct fname) + dirent->name_len + 1; 445 new_fn = kzalloc(len, GFP_KERNEL); 446 if (!new_fn) 447 return -ENOMEM; 448 new_fn->hash = hash; 449 new_fn->minor_hash = minor_hash; 450 new_fn->inode = le32_to_cpu(dirent->inode); 451 new_fn->name_len = dirent->name_len; 452 new_fn->file_type = dirent->file_type; 453 memcpy(new_fn->name, dirent->name, dirent->name_len); 454 new_fn->name[dirent->name_len] = 0; 455 456 while (*p) { 457 parent = *p; 458 fname = rb_entry(parent, struct fname, rb_hash); 459 460 /* 461 * If the hash and minor hash match up, then we put 462 * them on a linked list. This rarely happens... 463 */ 464 if ((new_fn->hash == fname->hash) && 465 (new_fn->minor_hash == fname->minor_hash)) { 466 new_fn->next = fname->next; 467 fname->next = new_fn; 468 return 0; 469 } 470 471 if (new_fn->hash < fname->hash) 472 p = &(*p)->rb_left; 473 else if (new_fn->hash > fname->hash) 474 p = &(*p)->rb_right; 475 else if (new_fn->minor_hash < fname->minor_hash) 476 p = &(*p)->rb_left; 477 else /* if (new_fn->minor_hash > fname->minor_hash) */ 478 p = &(*p)->rb_right; 479 } 480 481 rb_link_node(&new_fn->rb_hash, parent, p); 482 rb_insert_color(&new_fn->rb_hash, &info->root); 483 return 0; 484 } 485 486 487 488 /* 489 * This is a helper function for ext4_dx_readdir. It calls filldir 490 * for all entres on the fname linked list. (Normally there is only 491 * one entry on the linked list, unless there are 62 bit hash collisions.) 492 */ 493 static int call_filldir(struct file *filp, void *dirent, 494 filldir_t filldir, struct fname *fname) 495 { 496 struct dir_private_info *info = filp->private_data; 497 loff_t curr_pos; 498 struct inode *inode = filp->f_path.dentry->d_inode; 499 struct super_block *sb; 500 int error; 501 502 sb = inode->i_sb; 503 504 if (!fname) { 505 ext4_msg(sb, KERN_ERR, "%s:%d: inode #%lu: comm %s: " 506 "called with null fname?!?", __func__, __LINE__, 507 inode->i_ino, current->comm); 508 return 0; 509 } 510 curr_pos = hash2pos(filp, fname->hash, fname->minor_hash); 511 while (fname) { 512 error = filldir(dirent, fname->name, 513 fname->name_len, curr_pos, 514 fname->inode, 515 get_dtype(sb, fname->file_type)); 516 if (error) { 517 filp->f_pos = curr_pos; 518 info->extra_fname = fname; 519 return error; 520 } 521 fname = fname->next; 522 } 523 return 0; 524 } 525 526 static int ext4_dx_readdir(struct file *filp, 527 void *dirent, filldir_t filldir) 528 { 529 struct dir_private_info *info = filp->private_data; 530 struct inode *inode = filp->f_path.dentry->d_inode; 531 struct fname *fname; 532 int ret; 533 534 if (!info) { 535 info = ext4_htree_create_dir_info(filp, filp->f_pos); 536 if (!info) 537 return -ENOMEM; 538 filp->private_data = info; 539 } 540 541 if (filp->f_pos == ext4_get_htree_eof(filp)) 542 return 0; /* EOF */ 543 544 /* Some one has messed with f_pos; reset the world */ 545 if (info->last_pos != filp->f_pos) { 546 free_rb_tree_fname(&info->root); 547 info->curr_node = NULL; 548 info->extra_fname = NULL; 549 info->curr_hash = pos2maj_hash(filp, filp->f_pos); 550 info->curr_minor_hash = pos2min_hash(filp, filp->f_pos); 551 } 552 553 /* 554 * If there are any leftover names on the hash collision 555 * chain, return them first. 556 */ 557 if (info->extra_fname) { 558 if (call_filldir(filp, dirent, filldir, info->extra_fname)) 559 goto finished; 560 info->extra_fname = NULL; 561 goto next_node; 562 } else if (!info->curr_node) 563 info->curr_node = rb_first(&info->root); 564 565 while (1) { 566 /* 567 * Fill the rbtree if we have no more entries, 568 * or the inode has changed since we last read in the 569 * cached entries. 570 */ 571 if ((!info->curr_node) || 572 (filp->f_version != inode->i_version)) { 573 info->curr_node = NULL; 574 free_rb_tree_fname(&info->root); 575 filp->f_version = inode->i_version; 576 ret = ext4_htree_fill_tree(filp, info->curr_hash, 577 info->curr_minor_hash, 578 &info->next_hash); 579 if (ret < 0) 580 return ret; 581 if (ret == 0) { 582 filp->f_pos = ext4_get_htree_eof(filp); 583 break; 584 } 585 info->curr_node = rb_first(&info->root); 586 } 587 588 fname = rb_entry(info->curr_node, struct fname, rb_hash); 589 info->curr_hash = fname->hash; 590 info->curr_minor_hash = fname->minor_hash; 591 if (call_filldir(filp, dirent, filldir, fname)) 592 break; 593 next_node: 594 info->curr_node = rb_next(info->curr_node); 595 if (info->curr_node) { 596 fname = rb_entry(info->curr_node, struct fname, 597 rb_hash); 598 info->curr_hash = fname->hash; 599 info->curr_minor_hash = fname->minor_hash; 600 } else { 601 if (info->next_hash == ~0) { 602 filp->f_pos = ext4_get_htree_eof(filp); 603 break; 604 } 605 info->curr_hash = info->next_hash; 606 info->curr_minor_hash = 0; 607 } 608 } 609 finished: 610 info->last_pos = filp->f_pos; 611 return 0; 612 } 613 614 static int ext4_release_dir(struct inode *inode, struct file *filp) 615 { 616 if (filp->private_data) 617 ext4_htree_free_dir_info(filp->private_data); 618 619 return 0; 620 } 621 622 const struct file_operations ext4_dir_operations = { 623 .llseek = ext4_dir_llseek, 624 .read = generic_read_dir, 625 .readdir = ext4_readdir, 626 .unlocked_ioctl = ext4_ioctl, 627 #ifdef CONFIG_COMPAT 628 .compat_ioctl = ext4_compat_ioctl, 629 #endif 630 .fsync = ext4_sync_file, 631 .release = ext4_release_dir, 632 }; 633