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 return 1; 51 52 return 0; 53 } 54 55 /* 56 * Return 0 if the directory entry is OK, and 1 if there is a problem 57 * 58 * Note: this is the opposite of what ext2 and ext3 historically returned... 59 * 60 * bh passed here can be an inode block or a dir data block, depending 61 * on the inode inline data flag. 62 */ 63 int __ext4_check_dir_entry(const char *function, unsigned int line, 64 struct inode *dir, struct file *filp, 65 struct ext4_dir_entry_2 *de, 66 struct buffer_head *bh, char *buf, int size, 67 unsigned int offset) 68 { 69 const char *error_msg = NULL; 70 const int rlen = ext4_rec_len_from_disk(de->rec_len, 71 dir->i_sb->s_blocksize); 72 73 if (unlikely(rlen < EXT4_DIR_REC_LEN(1))) 74 error_msg = "rec_len is smaller than minimal"; 75 else if (unlikely(rlen % 4 != 0)) 76 error_msg = "rec_len % 4 != 0"; 77 else if (unlikely(rlen < EXT4_DIR_REC_LEN(de->name_len))) 78 error_msg = "rec_len is too small for name_len"; 79 else if (unlikely(((char *) de - buf) + rlen > size)) 80 error_msg = "directory entry across range"; 81 else if (unlikely(le32_to_cpu(de->inode) > 82 le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count))) 83 error_msg = "inode out of bounds"; 84 else 85 return 0; 86 87 if (filp) 88 ext4_error_file(filp, function, line, bh->b_blocknr, 89 "bad entry in directory: %s - offset=%u(%u), " 90 "inode=%u, rec_len=%d, name_len=%d", 91 error_msg, (unsigned) (offset % size), 92 offset, le32_to_cpu(de->inode), 93 rlen, de->name_len); 94 else 95 ext4_error_inode(dir, function, line, bh->b_blocknr, 96 "bad entry in directory: %s - offset=%u(%u), " 97 "inode=%u, rec_len=%d, name_len=%d", 98 error_msg, (unsigned) (offset % size), 99 offset, le32_to_cpu(de->inode), 100 rlen, de->name_len); 101 102 return 1; 103 } 104 105 static int ext4_readdir(struct file *filp, 106 void *dirent, filldir_t filldir) 107 { 108 int error = 0; 109 unsigned int offset; 110 int i, stored; 111 struct ext4_dir_entry_2 *de; 112 int err; 113 struct inode *inode = filp->f_path.dentry->d_inode; 114 struct super_block *sb = inode->i_sb; 115 int ret = 0; 116 int dir_has_error = 0; 117 118 if (ext4_has_inline_data(inode)) { 119 int has_inline_data = 1; 120 ret = ext4_read_inline_dir(filp, dirent, filldir, 121 &has_inline_data); 122 if (has_inline_data) 123 return ret; 124 } 125 126 if (is_dx_dir(inode)) { 127 err = ext4_dx_readdir(filp, dirent, filldir); 128 if (err != ERR_BAD_DX_DIR) { 129 ret = err; 130 goto out; 131 } 132 /* 133 * We don't set the inode dirty flag since it's not 134 * critical that it get flushed back to the disk. 135 */ 136 ext4_clear_inode_flag(filp->f_path.dentry->d_inode, 137 EXT4_INODE_INDEX); 138 } 139 stored = 0; 140 offset = filp->f_pos & (sb->s_blocksize - 1); 141 142 while (!error && !stored && filp->f_pos < inode->i_size) { 143 struct ext4_map_blocks map; 144 struct buffer_head *bh = NULL; 145 146 map.m_lblk = filp->f_pos >> EXT4_BLOCK_SIZE_BITS(sb); 147 map.m_len = 1; 148 err = ext4_map_blocks(NULL, inode, &map, 0); 149 if (err > 0) { 150 pgoff_t index = map.m_pblk >> 151 (PAGE_CACHE_SHIFT - inode->i_blkbits); 152 if (!ra_has_index(&filp->f_ra, index)) 153 page_cache_sync_readahead( 154 sb->s_bdev->bd_inode->i_mapping, 155 &filp->f_ra, filp, 156 index, 1); 157 filp->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT; 158 bh = ext4_bread(NULL, inode, map.m_lblk, 0, &err); 159 } 160 161 /* 162 * We ignore I/O errors on directories so users have a chance 163 * of recovering data when there's a bad sector 164 */ 165 if (!bh) { 166 if (!dir_has_error) { 167 EXT4_ERROR_FILE(filp, 0, 168 "directory contains a " 169 "hole at offset %llu", 170 (unsigned long long) filp->f_pos); 171 dir_has_error = 1; 172 } 173 /* corrupt size? Maybe no more blocks to read */ 174 if (filp->f_pos > inode->i_blocks << 9) 175 break; 176 filp->f_pos += sb->s_blocksize - offset; 177 continue; 178 } 179 180 /* Check the checksum */ 181 if (!buffer_verified(bh) && 182 !ext4_dirent_csum_verify(inode, 183 (struct ext4_dir_entry *)bh->b_data)) { 184 EXT4_ERROR_FILE(filp, 0, "directory fails checksum " 185 "at offset %llu", 186 (unsigned long long)filp->f_pos); 187 filp->f_pos += sb->s_blocksize - offset; 188 continue; 189 } 190 set_buffer_verified(bh); 191 192 revalidate: 193 /* If the dir block has changed since the last call to 194 * readdir(2), then we might be pointing to an invalid 195 * dirent right now. Scan from the start of the block 196 * to make sure. */ 197 if (filp->f_version != inode->i_version) { 198 for (i = 0; i < sb->s_blocksize && i < offset; ) { 199 de = (struct ext4_dir_entry_2 *) 200 (bh->b_data + i); 201 /* It's too expensive to do a full 202 * dirent test each time round this 203 * loop, but we do have to test at 204 * least that it is non-zero. A 205 * failure will be detected in the 206 * dirent test below. */ 207 if (ext4_rec_len_from_disk(de->rec_len, 208 sb->s_blocksize) < EXT4_DIR_REC_LEN(1)) 209 break; 210 i += ext4_rec_len_from_disk(de->rec_len, 211 sb->s_blocksize); 212 } 213 offset = i; 214 filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1)) 215 | offset; 216 filp->f_version = inode->i_version; 217 } 218 219 while (!error && filp->f_pos < inode->i_size 220 && offset < sb->s_blocksize) { 221 de = (struct ext4_dir_entry_2 *) (bh->b_data + offset); 222 if (ext4_check_dir_entry(inode, filp, de, bh, 223 bh->b_data, bh->b_size, 224 offset)) { 225 /* 226 * On error, skip the f_pos to the next block 227 */ 228 filp->f_pos = (filp->f_pos | 229 (sb->s_blocksize - 1)) + 1; 230 brelse(bh); 231 ret = stored; 232 goto out; 233 } 234 offset += ext4_rec_len_from_disk(de->rec_len, 235 sb->s_blocksize); 236 if (le32_to_cpu(de->inode)) { 237 /* We might block in the next section 238 * if the data destination is 239 * currently swapped out. So, use a 240 * version stamp to detect whether or 241 * not the directory has been modified 242 * during the copy operation. 243 */ 244 u64 version = filp->f_version; 245 246 error = filldir(dirent, de->name, 247 de->name_len, 248 filp->f_pos, 249 le32_to_cpu(de->inode), 250 get_dtype(sb, de->file_type)); 251 if (error) 252 break; 253 if (version != filp->f_version) 254 goto revalidate; 255 stored++; 256 } 257 filp->f_pos += ext4_rec_len_from_disk(de->rec_len, 258 sb->s_blocksize); 259 } 260 offset = 0; 261 brelse(bh); 262 } 263 out: 264 return ret; 265 } 266 267 static inline int is_32bit_api(void) 268 { 269 #ifdef CONFIG_COMPAT 270 return is_compat_task(); 271 #else 272 return (BITS_PER_LONG == 32); 273 #endif 274 } 275 276 /* 277 * These functions convert from the major/minor hash to an f_pos 278 * value for dx directories 279 * 280 * Upper layer (for example NFS) should specify FMODE_32BITHASH or 281 * FMODE_64BITHASH explicitly. On the other hand, we allow ext4 to be mounted 282 * directly on both 32-bit and 64-bit nodes, under such case, neither 283 * FMODE_32BITHASH nor FMODE_64BITHASH is specified. 284 */ 285 static inline loff_t hash2pos(struct file *filp, __u32 major, __u32 minor) 286 { 287 if ((filp->f_mode & FMODE_32BITHASH) || 288 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) 289 return major >> 1; 290 else 291 return ((__u64)(major >> 1) << 32) | (__u64)minor; 292 } 293 294 static inline __u32 pos2maj_hash(struct file *filp, loff_t pos) 295 { 296 if ((filp->f_mode & FMODE_32BITHASH) || 297 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) 298 return (pos << 1) & 0xffffffff; 299 else 300 return ((pos >> 32) << 1) & 0xffffffff; 301 } 302 303 static inline __u32 pos2min_hash(struct file *filp, loff_t pos) 304 { 305 if ((filp->f_mode & FMODE_32BITHASH) || 306 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) 307 return 0; 308 else 309 return pos & 0xffffffff; 310 } 311 312 /* 313 * Return 32- or 64-bit end-of-file for dx directories 314 */ 315 static inline loff_t ext4_get_htree_eof(struct file *filp) 316 { 317 if ((filp->f_mode & FMODE_32BITHASH) || 318 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) 319 return EXT4_HTREE_EOF_32BIT; 320 else 321 return EXT4_HTREE_EOF_64BIT; 322 } 323 324 325 /* 326 * ext4_dir_llseek() calls generic_file_llseek_size to handle htree 327 * directories, where the "offset" is in terms of the filename hash 328 * value instead of the byte offset. 329 * 330 * Because we may return a 64-bit hash that is well beyond offset limits, 331 * we need to pass the max hash as the maximum allowable offset in 332 * the htree directory case. 333 * 334 * For non-htree, ext4_llseek already chooses the proper max offset. 335 */ 336 loff_t ext4_dir_llseek(struct file *file, loff_t offset, int whence) 337 { 338 struct inode *inode = file->f_mapping->host; 339 int dx_dir = is_dx_dir(inode); 340 loff_t htree_max = ext4_get_htree_eof(file); 341 342 if (likely(dx_dir)) 343 return generic_file_llseek_size(file, offset, whence, 344 htree_max, htree_max); 345 else 346 return ext4_llseek(file, offset, whence); 347 } 348 349 /* 350 * This structure holds the nodes of the red-black tree used to store 351 * the directory entry in hash order. 352 */ 353 struct fname { 354 __u32 hash; 355 __u32 minor_hash; 356 struct rb_node rb_hash; 357 struct fname *next; 358 __u32 inode; 359 __u8 name_len; 360 __u8 file_type; 361 char name[0]; 362 }; 363 364 /* 365 * This functoin implements a non-recursive way of freeing all of the 366 * nodes in the red-black tree. 367 */ 368 static void free_rb_tree_fname(struct rb_root *root) 369 { 370 struct rb_node *n = root->rb_node; 371 struct rb_node *parent; 372 struct fname *fname; 373 374 while (n) { 375 /* Do the node's children first */ 376 if (n->rb_left) { 377 n = n->rb_left; 378 continue; 379 } 380 if (n->rb_right) { 381 n = n->rb_right; 382 continue; 383 } 384 /* 385 * The node has no children; free it, and then zero 386 * out parent's link to it. Finally go to the 387 * beginning of the loop and try to free the parent 388 * node. 389 */ 390 parent = rb_parent(n); 391 fname = rb_entry(n, struct fname, rb_hash); 392 while (fname) { 393 struct fname *old = fname; 394 fname = fname->next; 395 kfree(old); 396 } 397 if (!parent) 398 *root = RB_ROOT; 399 else if (parent->rb_left == n) 400 parent->rb_left = NULL; 401 else if (parent->rb_right == n) 402 parent->rb_right = NULL; 403 n = parent; 404 } 405 } 406 407 408 static struct dir_private_info *ext4_htree_create_dir_info(struct file *filp, 409 loff_t pos) 410 { 411 struct dir_private_info *p; 412 413 p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL); 414 if (!p) 415 return NULL; 416 p->curr_hash = pos2maj_hash(filp, pos); 417 p->curr_minor_hash = pos2min_hash(filp, pos); 418 return p; 419 } 420 421 void ext4_htree_free_dir_info(struct dir_private_info *p) 422 { 423 free_rb_tree_fname(&p->root); 424 kfree(p); 425 } 426 427 /* 428 * Given a directory entry, enter it into the fname rb tree. 429 */ 430 int ext4_htree_store_dirent(struct file *dir_file, __u32 hash, 431 __u32 minor_hash, 432 struct ext4_dir_entry_2 *dirent) 433 { 434 struct rb_node **p, *parent = NULL; 435 struct fname *fname, *new_fn; 436 struct dir_private_info *info; 437 int len; 438 439 info = dir_file->private_data; 440 p = &info->root.rb_node; 441 442 /* Create and allocate the fname structure */ 443 len = sizeof(struct fname) + dirent->name_len + 1; 444 new_fn = kzalloc(len, GFP_KERNEL); 445 if (!new_fn) 446 return -ENOMEM; 447 new_fn->hash = hash; 448 new_fn->minor_hash = minor_hash; 449 new_fn->inode = le32_to_cpu(dirent->inode); 450 new_fn->name_len = dirent->name_len; 451 new_fn->file_type = dirent->file_type; 452 memcpy(new_fn->name, dirent->name, dirent->name_len); 453 new_fn->name[dirent->name_len] = 0; 454 455 while (*p) { 456 parent = *p; 457 fname = rb_entry(parent, struct fname, rb_hash); 458 459 /* 460 * If the hash and minor hash match up, then we put 461 * them on a linked list. This rarely happens... 462 */ 463 if ((new_fn->hash == fname->hash) && 464 (new_fn->minor_hash == fname->minor_hash)) { 465 new_fn->next = fname->next; 466 fname->next = new_fn; 467 return 0; 468 } 469 470 if (new_fn->hash < fname->hash) 471 p = &(*p)->rb_left; 472 else if (new_fn->hash > fname->hash) 473 p = &(*p)->rb_right; 474 else if (new_fn->minor_hash < fname->minor_hash) 475 p = &(*p)->rb_left; 476 else /* if (new_fn->minor_hash > fname->minor_hash) */ 477 p = &(*p)->rb_right; 478 } 479 480 rb_link_node(&new_fn->rb_hash, parent, p); 481 rb_insert_color(&new_fn->rb_hash, &info->root); 482 return 0; 483 } 484 485 486 487 /* 488 * This is a helper function for ext4_dx_readdir. It calls filldir 489 * for all entres on the fname linked list. (Normally there is only 490 * one entry on the linked list, unless there are 62 bit hash collisions.) 491 */ 492 static int call_filldir(struct file *filp, void *dirent, 493 filldir_t filldir, struct fname *fname) 494 { 495 struct dir_private_info *info = filp->private_data; 496 loff_t curr_pos; 497 struct inode *inode = filp->f_path.dentry->d_inode; 498 struct super_block *sb; 499 int error; 500 501 sb = inode->i_sb; 502 503 if (!fname) { 504 ext4_msg(sb, KERN_ERR, "%s:%d: inode #%lu: comm %s: " 505 "called with null fname?!?", __func__, __LINE__, 506 inode->i_ino, current->comm); 507 return 0; 508 } 509 curr_pos = hash2pos(filp, fname->hash, fname->minor_hash); 510 while (fname) { 511 error = filldir(dirent, fname->name, 512 fname->name_len, curr_pos, 513 fname->inode, 514 get_dtype(sb, fname->file_type)); 515 if (error) { 516 filp->f_pos = curr_pos; 517 info->extra_fname = fname; 518 return error; 519 } 520 fname = fname->next; 521 } 522 return 0; 523 } 524 525 static int ext4_dx_readdir(struct file *filp, 526 void *dirent, filldir_t filldir) 527 { 528 struct dir_private_info *info = filp->private_data; 529 struct inode *inode = filp->f_path.dentry->d_inode; 530 struct fname *fname; 531 int ret; 532 533 if (!info) { 534 info = ext4_htree_create_dir_info(filp, filp->f_pos); 535 if (!info) 536 return -ENOMEM; 537 filp->private_data = info; 538 } 539 540 if (filp->f_pos == ext4_get_htree_eof(filp)) 541 return 0; /* EOF */ 542 543 /* Some one has messed with f_pos; reset the world */ 544 if (info->last_pos != filp->f_pos) { 545 free_rb_tree_fname(&info->root); 546 info->curr_node = NULL; 547 info->extra_fname = NULL; 548 info->curr_hash = pos2maj_hash(filp, filp->f_pos); 549 info->curr_minor_hash = pos2min_hash(filp, filp->f_pos); 550 } 551 552 /* 553 * If there are any leftover names on the hash collision 554 * chain, return them first. 555 */ 556 if (info->extra_fname) { 557 if (call_filldir(filp, dirent, filldir, info->extra_fname)) 558 goto finished; 559 info->extra_fname = NULL; 560 goto next_node; 561 } else if (!info->curr_node) 562 info->curr_node = rb_first(&info->root); 563 564 while (1) { 565 /* 566 * Fill the rbtree if we have no more entries, 567 * or the inode has changed since we last read in the 568 * cached entries. 569 */ 570 if ((!info->curr_node) || 571 (filp->f_version != inode->i_version)) { 572 info->curr_node = NULL; 573 free_rb_tree_fname(&info->root); 574 filp->f_version = inode->i_version; 575 ret = ext4_htree_fill_tree(filp, info->curr_hash, 576 info->curr_minor_hash, 577 &info->next_hash); 578 if (ret < 0) 579 return ret; 580 if (ret == 0) { 581 filp->f_pos = ext4_get_htree_eof(filp); 582 break; 583 } 584 info->curr_node = rb_first(&info->root); 585 } 586 587 fname = rb_entry(info->curr_node, struct fname, rb_hash); 588 info->curr_hash = fname->hash; 589 info->curr_minor_hash = fname->minor_hash; 590 if (call_filldir(filp, dirent, filldir, fname)) 591 break; 592 next_node: 593 info->curr_node = rb_next(info->curr_node); 594 if (info->curr_node) { 595 fname = rb_entry(info->curr_node, struct fname, 596 rb_hash); 597 info->curr_hash = fname->hash; 598 info->curr_minor_hash = fname->minor_hash; 599 } else { 600 if (info->next_hash == ~0) { 601 filp->f_pos = ext4_get_htree_eof(filp); 602 break; 603 } 604 info->curr_hash = info->next_hash; 605 info->curr_minor_hash = 0; 606 } 607 } 608 finished: 609 info->last_pos = filp->f_pos; 610 return 0; 611 } 612 613 static int ext4_release_dir(struct inode *inode, struct file *filp) 614 { 615 if (filp->private_data) 616 ext4_htree_free_dir_info(filp->private_data); 617 618 return 0; 619 } 620 621 const struct file_operations ext4_dir_operations = { 622 .llseek = ext4_dir_llseek, 623 .read = generic_read_dir, 624 .readdir = ext4_readdir, 625 .unlocked_ioctl = ext4_ioctl, 626 #ifdef CONFIG_COMPAT 627 .compat_ioctl = ext4_compat_ioctl, 628 #endif 629 .fsync = ext4_sync_file, 630 .release = ext4_release_dir, 631 }; 632