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 #include "xattr.h" 31 32 static int ext4_dx_readdir(struct file *filp, 33 void *dirent, filldir_t filldir); 34 35 /** 36 * Check if the given dir-inode refers to an htree-indexed directory 37 * (or a directory which chould potentially get coverted to use htree 38 * indexing). 39 * 40 * Return 1 if it is a dx dir, 0 if not 41 */ 42 static int is_dx_dir(struct inode *inode) 43 { 44 struct super_block *sb = inode->i_sb; 45 46 if (EXT4_HAS_COMPAT_FEATURE(inode->i_sb, 47 EXT4_FEATURE_COMPAT_DIR_INDEX) && 48 ((ext4_test_inode_flag(inode, EXT4_INODE_INDEX)) || 49 ((inode->i_size >> sb->s_blocksize_bits) == 1) || 50 ext4_has_inline_data(inode))) 51 return 1; 52 53 return 0; 54 } 55 56 /* 57 * Return 0 if the directory entry is OK, and 1 if there is a problem 58 * 59 * Note: this is the opposite of what ext2 and ext3 historically returned... 60 * 61 * bh passed here can be an inode block or a dir data block, depending 62 * on the inode inline data flag. 63 */ 64 int __ext4_check_dir_entry(const char *function, unsigned int line, 65 struct inode *dir, struct file *filp, 66 struct ext4_dir_entry_2 *de, 67 struct buffer_head *bh, char *buf, int size, 68 unsigned int offset) 69 { 70 const char *error_msg = NULL; 71 const int rlen = ext4_rec_len_from_disk(de->rec_len, 72 dir->i_sb->s_blocksize); 73 74 if (unlikely(rlen < EXT4_DIR_REC_LEN(1))) 75 error_msg = "rec_len is smaller than minimal"; 76 else if (unlikely(rlen % 4 != 0)) 77 error_msg = "rec_len % 4 != 0"; 78 else if (unlikely(rlen < EXT4_DIR_REC_LEN(de->name_len))) 79 error_msg = "rec_len is too small for name_len"; 80 else if (unlikely(((char *) de - buf) + rlen > size)) 81 error_msg = "directory entry across range"; 82 else if (unlikely(le32_to_cpu(de->inode) > 83 le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count))) 84 error_msg = "inode out of bounds"; 85 else 86 return 0; 87 88 if (filp) 89 ext4_error_file(filp, function, line, bh->b_blocknr, 90 "bad entry in directory: %s - offset=%u(%u), " 91 "inode=%u, rec_len=%d, name_len=%d", 92 error_msg, (unsigned) (offset % size), 93 offset, le32_to_cpu(de->inode), 94 rlen, de->name_len); 95 else 96 ext4_error_inode(dir, function, line, bh->b_blocknr, 97 "bad entry in directory: %s - offset=%u(%u), " 98 "inode=%u, rec_len=%d, name_len=%d", 99 error_msg, (unsigned) (offset % size), 100 offset, le32_to_cpu(de->inode), 101 rlen, de->name_len); 102 103 return 1; 104 } 105 106 static int ext4_readdir(struct file *filp, 107 void *dirent, filldir_t filldir) 108 { 109 int error = 0; 110 unsigned int offset; 111 int i, stored; 112 struct ext4_dir_entry_2 *de; 113 int err; 114 struct inode *inode = file_inode(filp); 115 struct super_block *sb = inode->i_sb; 116 int ret = 0; 117 int dir_has_error = 0; 118 119 if (is_dx_dir(inode)) { 120 err = ext4_dx_readdir(filp, dirent, filldir); 121 if (err != ERR_BAD_DX_DIR) { 122 ret = err; 123 goto out; 124 } 125 /* 126 * We don't set the inode dirty flag since it's not 127 * critical that it get flushed back to the disk. 128 */ 129 ext4_clear_inode_flag(file_inode(filp), 130 EXT4_INODE_INDEX); 131 } 132 133 if (ext4_has_inline_data(inode)) { 134 int has_inline_data = 1; 135 ret = ext4_read_inline_dir(filp, dirent, filldir, 136 &has_inline_data); 137 if (has_inline_data) 138 return ret; 139 } 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 brelse(bh); 191 continue; 192 } 193 set_buffer_verified(bh); 194 195 revalidate: 196 /* If the dir block has changed since the last call to 197 * readdir(2), then we might be pointing to an invalid 198 * dirent right now. Scan from the start of the block 199 * to make sure. */ 200 if (filp->f_version != inode->i_version) { 201 for (i = 0; i < sb->s_blocksize && i < offset; ) { 202 de = (struct ext4_dir_entry_2 *) 203 (bh->b_data + i); 204 /* It's too expensive to do a full 205 * dirent test each time round this 206 * loop, but we do have to test at 207 * least that it is non-zero. A 208 * failure will be detected in the 209 * dirent test below. */ 210 if (ext4_rec_len_from_disk(de->rec_len, 211 sb->s_blocksize) < EXT4_DIR_REC_LEN(1)) 212 break; 213 i += ext4_rec_len_from_disk(de->rec_len, 214 sb->s_blocksize); 215 } 216 offset = i; 217 filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1)) 218 | offset; 219 filp->f_version = inode->i_version; 220 } 221 222 while (!error && filp->f_pos < inode->i_size 223 && offset < sb->s_blocksize) { 224 de = (struct ext4_dir_entry_2 *) (bh->b_data + offset); 225 if (ext4_check_dir_entry(inode, filp, de, bh, 226 bh->b_data, bh->b_size, 227 offset)) { 228 /* 229 * On error, skip the f_pos to the next block 230 */ 231 filp->f_pos = (filp->f_pos | 232 (sb->s_blocksize - 1)) + 1; 233 brelse(bh); 234 ret = stored; 235 goto out; 236 } 237 offset += ext4_rec_len_from_disk(de->rec_len, 238 sb->s_blocksize); 239 if (le32_to_cpu(de->inode)) { 240 /* We might block in the next section 241 * if the data destination is 242 * currently swapped out. So, use a 243 * version stamp to detect whether or 244 * not the directory has been modified 245 * during the copy operation. 246 */ 247 u64 version = filp->f_version; 248 249 error = filldir(dirent, de->name, 250 de->name_len, 251 filp->f_pos, 252 le32_to_cpu(de->inode), 253 get_dtype(sb, de->file_type)); 254 if (error) 255 break; 256 if (version != filp->f_version) 257 goto revalidate; 258 stored++; 259 } 260 filp->f_pos += ext4_rec_len_from_disk(de->rec_len, 261 sb->s_blocksize); 262 } 263 offset = 0; 264 brelse(bh); 265 } 266 out: 267 return ret; 268 } 269 270 static inline int is_32bit_api(void) 271 { 272 #ifdef CONFIG_COMPAT 273 return is_compat_task(); 274 #else 275 return (BITS_PER_LONG == 32); 276 #endif 277 } 278 279 /* 280 * These functions convert from the major/minor hash to an f_pos 281 * value for dx directories 282 * 283 * Upper layer (for example NFS) should specify FMODE_32BITHASH or 284 * FMODE_64BITHASH explicitly. On the other hand, we allow ext4 to be mounted 285 * directly on both 32-bit and 64-bit nodes, under such case, neither 286 * FMODE_32BITHASH nor FMODE_64BITHASH is specified. 287 */ 288 static inline loff_t hash2pos(struct file *filp, __u32 major, __u32 minor) 289 { 290 if ((filp->f_mode & FMODE_32BITHASH) || 291 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) 292 return major >> 1; 293 else 294 return ((__u64)(major >> 1) << 32) | (__u64)minor; 295 } 296 297 static inline __u32 pos2maj_hash(struct file *filp, loff_t pos) 298 { 299 if ((filp->f_mode & FMODE_32BITHASH) || 300 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) 301 return (pos << 1) & 0xffffffff; 302 else 303 return ((pos >> 32) << 1) & 0xffffffff; 304 } 305 306 static inline __u32 pos2min_hash(struct file *filp, loff_t pos) 307 { 308 if ((filp->f_mode & FMODE_32BITHASH) || 309 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) 310 return 0; 311 else 312 return pos & 0xffffffff; 313 } 314 315 /* 316 * Return 32- or 64-bit end-of-file for dx directories 317 */ 318 static inline loff_t ext4_get_htree_eof(struct file *filp) 319 { 320 if ((filp->f_mode & FMODE_32BITHASH) || 321 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) 322 return EXT4_HTREE_EOF_32BIT; 323 else 324 return EXT4_HTREE_EOF_64BIT; 325 } 326 327 328 /* 329 * ext4_dir_llseek() calls generic_file_llseek_size to handle htree 330 * directories, where the "offset" is in terms of the filename hash 331 * value instead of the byte offset. 332 * 333 * Because we may return a 64-bit hash that is well beyond offset limits, 334 * we need to pass the max hash as the maximum allowable offset in 335 * the htree directory case. 336 * 337 * For non-htree, ext4_llseek already chooses the proper max offset. 338 */ 339 static loff_t ext4_dir_llseek(struct file *file, loff_t offset, int whence) 340 { 341 struct inode *inode = file->f_mapping->host; 342 int dx_dir = is_dx_dir(inode); 343 loff_t htree_max = ext4_get_htree_eof(file); 344 345 if (likely(dx_dir)) 346 return generic_file_llseek_size(file, offset, whence, 347 htree_max, htree_max); 348 else 349 return ext4_llseek(file, offset, whence); 350 } 351 352 /* 353 * This structure holds the nodes of the red-black tree used to store 354 * the directory entry in hash order. 355 */ 356 struct fname { 357 __u32 hash; 358 __u32 minor_hash; 359 struct rb_node rb_hash; 360 struct fname *next; 361 __u32 inode; 362 __u8 name_len; 363 __u8 file_type; 364 char name[0]; 365 }; 366 367 /* 368 * This functoin implements a non-recursive way of freeing all of the 369 * nodes in the red-black tree. 370 */ 371 static void free_rb_tree_fname(struct rb_root *root) 372 { 373 struct rb_node *n = root->rb_node; 374 struct rb_node *parent; 375 struct fname *fname; 376 377 while (n) { 378 /* Do the node's children first */ 379 if (n->rb_left) { 380 n = n->rb_left; 381 continue; 382 } 383 if (n->rb_right) { 384 n = n->rb_right; 385 continue; 386 } 387 /* 388 * The node has no children; free it, and then zero 389 * out parent's link to it. Finally go to the 390 * beginning of the loop and try to free the parent 391 * node. 392 */ 393 parent = rb_parent(n); 394 fname = rb_entry(n, struct fname, rb_hash); 395 while (fname) { 396 struct fname *old = fname; 397 fname = fname->next; 398 kfree(old); 399 } 400 if (!parent) 401 *root = RB_ROOT; 402 else if (parent->rb_left == n) 403 parent->rb_left = NULL; 404 else if (parent->rb_right == n) 405 parent->rb_right = NULL; 406 n = parent; 407 } 408 } 409 410 411 static struct dir_private_info *ext4_htree_create_dir_info(struct file *filp, 412 loff_t pos) 413 { 414 struct dir_private_info *p; 415 416 p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL); 417 if (!p) 418 return NULL; 419 p->curr_hash = pos2maj_hash(filp, pos); 420 p->curr_minor_hash = pos2min_hash(filp, pos); 421 return p; 422 } 423 424 void ext4_htree_free_dir_info(struct dir_private_info *p) 425 { 426 free_rb_tree_fname(&p->root); 427 kfree(p); 428 } 429 430 /* 431 * Given a directory entry, enter it into the fname rb tree. 432 */ 433 int ext4_htree_store_dirent(struct file *dir_file, __u32 hash, 434 __u32 minor_hash, 435 struct ext4_dir_entry_2 *dirent) 436 { 437 struct rb_node **p, *parent = NULL; 438 struct fname *fname, *new_fn; 439 struct dir_private_info *info; 440 int len; 441 442 info = dir_file->private_data; 443 p = &info->root.rb_node; 444 445 /* Create and allocate the fname structure */ 446 len = sizeof(struct fname) + dirent->name_len + 1; 447 new_fn = kzalloc(len, GFP_KERNEL); 448 if (!new_fn) 449 return -ENOMEM; 450 new_fn->hash = hash; 451 new_fn->minor_hash = minor_hash; 452 new_fn->inode = le32_to_cpu(dirent->inode); 453 new_fn->name_len = dirent->name_len; 454 new_fn->file_type = dirent->file_type; 455 memcpy(new_fn->name, dirent->name, dirent->name_len); 456 new_fn->name[dirent->name_len] = 0; 457 458 while (*p) { 459 parent = *p; 460 fname = rb_entry(parent, struct fname, rb_hash); 461 462 /* 463 * If the hash and minor hash match up, then we put 464 * them on a linked list. This rarely happens... 465 */ 466 if ((new_fn->hash == fname->hash) && 467 (new_fn->minor_hash == fname->minor_hash)) { 468 new_fn->next = fname->next; 469 fname->next = new_fn; 470 return 0; 471 } 472 473 if (new_fn->hash < fname->hash) 474 p = &(*p)->rb_left; 475 else if (new_fn->hash > fname->hash) 476 p = &(*p)->rb_right; 477 else if (new_fn->minor_hash < fname->minor_hash) 478 p = &(*p)->rb_left; 479 else /* if (new_fn->minor_hash > fname->minor_hash) */ 480 p = &(*p)->rb_right; 481 } 482 483 rb_link_node(&new_fn->rb_hash, parent, p); 484 rb_insert_color(&new_fn->rb_hash, &info->root); 485 return 0; 486 } 487 488 489 490 /* 491 * This is a helper function for ext4_dx_readdir. It calls filldir 492 * for all entres on the fname linked list. (Normally there is only 493 * one entry on the linked list, unless there are 62 bit hash collisions.) 494 */ 495 static int call_filldir(struct file *filp, void *dirent, 496 filldir_t filldir, struct fname *fname) 497 { 498 struct dir_private_info *info = filp->private_data; 499 loff_t curr_pos; 500 struct inode *inode = file_inode(filp); 501 struct super_block *sb; 502 int error; 503 504 sb = inode->i_sb; 505 506 if (!fname) { 507 ext4_msg(sb, KERN_ERR, "%s:%d: inode #%lu: comm %s: " 508 "called with null fname?!?", __func__, __LINE__, 509 inode->i_ino, current->comm); 510 return 0; 511 } 512 curr_pos = hash2pos(filp, fname->hash, fname->minor_hash); 513 while (fname) { 514 error = filldir(dirent, fname->name, 515 fname->name_len, curr_pos, 516 fname->inode, 517 get_dtype(sb, fname->file_type)); 518 if (error) { 519 filp->f_pos = curr_pos; 520 info->extra_fname = fname; 521 return error; 522 } 523 fname = fname->next; 524 } 525 return 0; 526 } 527 528 static int ext4_dx_readdir(struct file *filp, 529 void *dirent, filldir_t filldir) 530 { 531 struct dir_private_info *info = filp->private_data; 532 struct inode *inode = file_inode(filp); 533 struct fname *fname; 534 int ret; 535 536 if (!info) { 537 info = ext4_htree_create_dir_info(filp, filp->f_pos); 538 if (!info) 539 return -ENOMEM; 540 filp->private_data = info; 541 } 542 543 if (filp->f_pos == ext4_get_htree_eof(filp)) 544 return 0; /* EOF */ 545 546 /* Some one has messed with f_pos; reset the world */ 547 if (info->last_pos != filp->f_pos) { 548 free_rb_tree_fname(&info->root); 549 info->curr_node = NULL; 550 info->extra_fname = NULL; 551 info->curr_hash = pos2maj_hash(filp, filp->f_pos); 552 info->curr_minor_hash = pos2min_hash(filp, filp->f_pos); 553 } 554 555 /* 556 * If there are any leftover names on the hash collision 557 * chain, return them first. 558 */ 559 if (info->extra_fname) { 560 if (call_filldir(filp, dirent, filldir, info->extra_fname)) 561 goto finished; 562 info->extra_fname = NULL; 563 goto next_node; 564 } else if (!info->curr_node) 565 info->curr_node = rb_first(&info->root); 566 567 while (1) { 568 /* 569 * Fill the rbtree if we have no more entries, 570 * or the inode has changed since we last read in the 571 * cached entries. 572 */ 573 if ((!info->curr_node) || 574 (filp->f_version != inode->i_version)) { 575 info->curr_node = NULL; 576 free_rb_tree_fname(&info->root); 577 filp->f_version = inode->i_version; 578 ret = ext4_htree_fill_tree(filp, info->curr_hash, 579 info->curr_minor_hash, 580 &info->next_hash); 581 if (ret < 0) 582 return ret; 583 if (ret == 0) { 584 filp->f_pos = ext4_get_htree_eof(filp); 585 break; 586 } 587 info->curr_node = rb_first(&info->root); 588 } 589 590 fname = rb_entry(info->curr_node, struct fname, rb_hash); 591 info->curr_hash = fname->hash; 592 info->curr_minor_hash = fname->minor_hash; 593 if (call_filldir(filp, dirent, filldir, fname)) 594 break; 595 next_node: 596 info->curr_node = rb_next(info->curr_node); 597 if (info->curr_node) { 598 fname = rb_entry(info->curr_node, struct fname, 599 rb_hash); 600 info->curr_hash = fname->hash; 601 info->curr_minor_hash = fname->minor_hash; 602 } else { 603 if (info->next_hash == ~0) { 604 filp->f_pos = ext4_get_htree_eof(filp); 605 break; 606 } 607 info->curr_hash = info->next_hash; 608 info->curr_minor_hash = 0; 609 } 610 } 611 finished: 612 info->last_pos = filp->f_pos; 613 return 0; 614 } 615 616 static int ext4_release_dir(struct inode *inode, struct file *filp) 617 { 618 if (filp->private_data) 619 ext4_htree_free_dir_info(filp->private_data); 620 621 return 0; 622 } 623 624 const struct file_operations ext4_dir_operations = { 625 .llseek = ext4_dir_llseek, 626 .read = generic_read_dir, 627 .readdir = ext4_readdir, 628 .unlocked_ioctl = ext4_ioctl, 629 #ifdef CONFIG_COMPAT 630 .compat_ioctl = ext4_compat_ioctl, 631 #endif 632 .fsync = ext4_sync_file, 633 .release = ext4_release_dir, 634 }; 635