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 *, struct dir_context *); 33 34 /** 35 * Check if the given dir-inode refers to an htree-indexed directory 36 * (or a directory which could potentially get converted to use htree 37 * indexing). 38 * 39 * Return 1 if it is a dx dir, 0 if not 40 */ 41 static int is_dx_dir(struct inode *inode) 42 { 43 struct super_block *sb = inode->i_sb; 44 45 if (EXT4_HAS_COMPAT_FEATURE(inode->i_sb, 46 EXT4_FEATURE_COMPAT_DIR_INDEX) && 47 ((ext4_test_inode_flag(inode, EXT4_INODE_INDEX)) || 48 ((inode->i_size >> sb->s_blocksize_bits) == 1) || 49 ext4_has_inline_data(inode))) 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 *file, struct dir_context *ctx) 106 { 107 unsigned int offset; 108 int i; 109 struct ext4_dir_entry_2 *de; 110 int err; 111 struct inode *inode = file_inode(file); 112 struct super_block *sb = inode->i_sb; 113 int dir_has_error = 0; 114 115 if (is_dx_dir(inode)) { 116 err = ext4_dx_readdir(file, ctx); 117 if (err != ERR_BAD_DX_DIR) { 118 return err; 119 } 120 /* 121 * We don't set the inode dirty flag since it's not 122 * critical that it get flushed back to the disk. 123 */ 124 ext4_clear_inode_flag(file_inode(file), 125 EXT4_INODE_INDEX); 126 } 127 128 if (ext4_has_inline_data(inode)) { 129 int has_inline_data = 1; 130 int ret = ext4_read_inline_dir(file, ctx, 131 &has_inline_data); 132 if (has_inline_data) 133 return ret; 134 } 135 136 offset = ctx->pos & (sb->s_blocksize - 1); 137 138 while (ctx->pos < inode->i_size) { 139 struct ext4_map_blocks map; 140 struct buffer_head *bh = NULL; 141 142 map.m_lblk = ctx->pos >> EXT4_BLOCK_SIZE_BITS(sb); 143 map.m_len = 1; 144 err = ext4_map_blocks(NULL, inode, &map, 0); 145 if (err > 0) { 146 pgoff_t index = map.m_pblk >> 147 (PAGE_CACHE_SHIFT - inode->i_blkbits); 148 if (!ra_has_index(&file->f_ra, index)) 149 page_cache_sync_readahead( 150 sb->s_bdev->bd_inode->i_mapping, 151 &file->f_ra, file, 152 index, 1); 153 file->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT; 154 bh = ext4_bread(NULL, inode, map.m_lblk, 0); 155 if (IS_ERR(bh)) 156 return PTR_ERR(bh); 157 } 158 159 if (!bh) { 160 if (!dir_has_error) { 161 EXT4_ERROR_FILE(file, 0, 162 "directory contains a " 163 "hole at offset %llu", 164 (unsigned long long) ctx->pos); 165 dir_has_error = 1; 166 } 167 /* corrupt size? Maybe no more blocks to read */ 168 if (ctx->pos > inode->i_blocks << 9) 169 break; 170 ctx->pos += sb->s_blocksize - offset; 171 continue; 172 } 173 174 /* Check the checksum */ 175 if (!buffer_verified(bh) && 176 !ext4_dirent_csum_verify(inode, 177 (struct ext4_dir_entry *)bh->b_data)) { 178 EXT4_ERROR_FILE(file, 0, "directory fails checksum " 179 "at offset %llu", 180 (unsigned long long)ctx->pos); 181 ctx->pos += sb->s_blocksize - offset; 182 brelse(bh); 183 continue; 184 } 185 set_buffer_verified(bh); 186 187 /* If the dir block has changed since the last call to 188 * readdir(2), then we might be pointing to an invalid 189 * dirent right now. Scan from the start of the block 190 * to make sure. */ 191 if (file->f_version != inode->i_version) { 192 for (i = 0; i < sb->s_blocksize && i < offset; ) { 193 de = (struct ext4_dir_entry_2 *) 194 (bh->b_data + i); 195 /* It's too expensive to do a full 196 * dirent test each time round this 197 * loop, but we do have to test at 198 * least that it is non-zero. A 199 * failure will be detected in the 200 * dirent test below. */ 201 if (ext4_rec_len_from_disk(de->rec_len, 202 sb->s_blocksize) < EXT4_DIR_REC_LEN(1)) 203 break; 204 i += ext4_rec_len_from_disk(de->rec_len, 205 sb->s_blocksize); 206 } 207 offset = i; 208 ctx->pos = (ctx->pos & ~(sb->s_blocksize - 1)) 209 | offset; 210 file->f_version = inode->i_version; 211 } 212 213 while (ctx->pos < inode->i_size 214 && offset < sb->s_blocksize) { 215 de = (struct ext4_dir_entry_2 *) (bh->b_data + offset); 216 if (ext4_check_dir_entry(inode, file, de, bh, 217 bh->b_data, bh->b_size, 218 offset)) { 219 /* 220 * On error, skip to the next block 221 */ 222 ctx->pos = (ctx->pos | 223 (sb->s_blocksize - 1)) + 1; 224 break; 225 } 226 offset += ext4_rec_len_from_disk(de->rec_len, 227 sb->s_blocksize); 228 if (le32_to_cpu(de->inode)) { 229 if (!dir_emit(ctx, de->name, 230 de->name_len, 231 le32_to_cpu(de->inode), 232 get_dtype(sb, de->file_type))) { 233 brelse(bh); 234 return 0; 235 } 236 } 237 ctx->pos += ext4_rec_len_from_disk(de->rec_len, 238 sb->s_blocksize); 239 } 240 offset = 0; 241 brelse(bh); 242 if (ctx->pos < inode->i_size) { 243 if (!dir_relax(inode)) 244 return 0; 245 } 246 } 247 return 0; 248 } 249 250 static inline int is_32bit_api(void) 251 { 252 #ifdef CONFIG_COMPAT 253 return is_compat_task(); 254 #else 255 return (BITS_PER_LONG == 32); 256 #endif 257 } 258 259 /* 260 * These functions convert from the major/minor hash to an f_pos 261 * value for dx directories 262 * 263 * Upper layer (for example NFS) should specify FMODE_32BITHASH or 264 * FMODE_64BITHASH explicitly. On the other hand, we allow ext4 to be mounted 265 * directly on both 32-bit and 64-bit nodes, under such case, neither 266 * FMODE_32BITHASH nor FMODE_64BITHASH is specified. 267 */ 268 static inline loff_t hash2pos(struct file *filp, __u32 major, __u32 minor) 269 { 270 if ((filp->f_mode & FMODE_32BITHASH) || 271 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) 272 return major >> 1; 273 else 274 return ((__u64)(major >> 1) << 32) | (__u64)minor; 275 } 276 277 static inline __u32 pos2maj_hash(struct file *filp, loff_t pos) 278 { 279 if ((filp->f_mode & FMODE_32BITHASH) || 280 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) 281 return (pos << 1) & 0xffffffff; 282 else 283 return ((pos >> 32) << 1) & 0xffffffff; 284 } 285 286 static inline __u32 pos2min_hash(struct file *filp, loff_t pos) 287 { 288 if ((filp->f_mode & FMODE_32BITHASH) || 289 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) 290 return 0; 291 else 292 return pos & 0xffffffff; 293 } 294 295 /* 296 * Return 32- or 64-bit end-of-file for dx directories 297 */ 298 static inline loff_t ext4_get_htree_eof(struct file *filp) 299 { 300 if ((filp->f_mode & FMODE_32BITHASH) || 301 (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api())) 302 return EXT4_HTREE_EOF_32BIT; 303 else 304 return EXT4_HTREE_EOF_64BIT; 305 } 306 307 308 /* 309 * ext4_dir_llseek() calls generic_file_llseek_size to handle htree 310 * directories, where the "offset" is in terms of the filename hash 311 * value instead of the byte offset. 312 * 313 * Because we may return a 64-bit hash that is well beyond offset limits, 314 * we need to pass the max hash as the maximum allowable offset in 315 * the htree directory case. 316 * 317 * For non-htree, ext4_llseek already chooses the proper max offset. 318 */ 319 static loff_t ext4_dir_llseek(struct file *file, loff_t offset, int whence) 320 { 321 struct inode *inode = file->f_mapping->host; 322 int dx_dir = is_dx_dir(inode); 323 loff_t htree_max = ext4_get_htree_eof(file); 324 325 if (likely(dx_dir)) 326 return generic_file_llseek_size(file, offset, whence, 327 htree_max, htree_max); 328 else 329 return ext4_llseek(file, offset, whence); 330 } 331 332 /* 333 * This structure holds the nodes of the red-black tree used to store 334 * the directory entry in hash order. 335 */ 336 struct fname { 337 __u32 hash; 338 __u32 minor_hash; 339 struct rb_node rb_hash; 340 struct fname *next; 341 __u32 inode; 342 __u8 name_len; 343 __u8 file_type; 344 char name[0]; 345 }; 346 347 /* 348 * This functoin implements a non-recursive way of freeing all of the 349 * nodes in the red-black tree. 350 */ 351 static void free_rb_tree_fname(struct rb_root *root) 352 { 353 struct fname *fname, *next; 354 355 rbtree_postorder_for_each_entry_safe(fname, next, root, rb_hash) 356 while (fname) { 357 struct fname *old = fname; 358 fname = fname->next; 359 kfree(old); 360 } 361 362 *root = RB_ROOT; 363 } 364 365 366 static struct dir_private_info *ext4_htree_create_dir_info(struct file *filp, 367 loff_t pos) 368 { 369 struct dir_private_info *p; 370 371 p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL); 372 if (!p) 373 return NULL; 374 p->curr_hash = pos2maj_hash(filp, pos); 375 p->curr_minor_hash = pos2min_hash(filp, pos); 376 return p; 377 } 378 379 void ext4_htree_free_dir_info(struct dir_private_info *p) 380 { 381 free_rb_tree_fname(&p->root); 382 kfree(p); 383 } 384 385 /* 386 * Given a directory entry, enter it into the fname rb tree. 387 */ 388 int ext4_htree_store_dirent(struct file *dir_file, __u32 hash, 389 __u32 minor_hash, 390 struct ext4_dir_entry_2 *dirent) 391 { 392 struct rb_node **p, *parent = NULL; 393 struct fname *fname, *new_fn; 394 struct dir_private_info *info; 395 int len; 396 397 info = dir_file->private_data; 398 p = &info->root.rb_node; 399 400 /* Create and allocate the fname structure */ 401 len = sizeof(struct fname) + dirent->name_len + 1; 402 new_fn = kzalloc(len, GFP_KERNEL); 403 if (!new_fn) 404 return -ENOMEM; 405 new_fn->hash = hash; 406 new_fn->minor_hash = minor_hash; 407 new_fn->inode = le32_to_cpu(dirent->inode); 408 new_fn->name_len = dirent->name_len; 409 new_fn->file_type = dirent->file_type; 410 memcpy(new_fn->name, dirent->name, dirent->name_len); 411 new_fn->name[dirent->name_len] = 0; 412 413 while (*p) { 414 parent = *p; 415 fname = rb_entry(parent, struct fname, rb_hash); 416 417 /* 418 * If the hash and minor hash match up, then we put 419 * them on a linked list. This rarely happens... 420 */ 421 if ((new_fn->hash == fname->hash) && 422 (new_fn->minor_hash == fname->minor_hash)) { 423 new_fn->next = fname->next; 424 fname->next = new_fn; 425 return 0; 426 } 427 428 if (new_fn->hash < fname->hash) 429 p = &(*p)->rb_left; 430 else if (new_fn->hash > fname->hash) 431 p = &(*p)->rb_right; 432 else if (new_fn->minor_hash < fname->minor_hash) 433 p = &(*p)->rb_left; 434 else /* if (new_fn->minor_hash > fname->minor_hash) */ 435 p = &(*p)->rb_right; 436 } 437 438 rb_link_node(&new_fn->rb_hash, parent, p); 439 rb_insert_color(&new_fn->rb_hash, &info->root); 440 return 0; 441 } 442 443 444 445 /* 446 * This is a helper function for ext4_dx_readdir. It calls filldir 447 * for all entres on the fname linked list. (Normally there is only 448 * one entry on the linked list, unless there are 62 bit hash collisions.) 449 */ 450 static int call_filldir(struct file *file, struct dir_context *ctx, 451 struct fname *fname) 452 { 453 struct dir_private_info *info = file->private_data; 454 struct inode *inode = file_inode(file); 455 struct super_block *sb = inode->i_sb; 456 457 if (!fname) { 458 ext4_msg(sb, KERN_ERR, "%s:%d: inode #%lu: comm %s: " 459 "called with null fname?!?", __func__, __LINE__, 460 inode->i_ino, current->comm); 461 return 0; 462 } 463 ctx->pos = hash2pos(file, fname->hash, fname->minor_hash); 464 while (fname) { 465 if (!dir_emit(ctx, fname->name, 466 fname->name_len, 467 fname->inode, 468 get_dtype(sb, fname->file_type))) { 469 info->extra_fname = fname; 470 return 1; 471 } 472 fname = fname->next; 473 } 474 return 0; 475 } 476 477 static int ext4_dx_readdir(struct file *file, struct dir_context *ctx) 478 { 479 struct dir_private_info *info = file->private_data; 480 struct inode *inode = file_inode(file); 481 struct fname *fname; 482 int ret; 483 484 if (!info) { 485 info = ext4_htree_create_dir_info(file, ctx->pos); 486 if (!info) 487 return -ENOMEM; 488 file->private_data = info; 489 } 490 491 if (ctx->pos == ext4_get_htree_eof(file)) 492 return 0; /* EOF */ 493 494 /* Some one has messed with f_pos; reset the world */ 495 if (info->last_pos != ctx->pos) { 496 free_rb_tree_fname(&info->root); 497 info->curr_node = NULL; 498 info->extra_fname = NULL; 499 info->curr_hash = pos2maj_hash(file, ctx->pos); 500 info->curr_minor_hash = pos2min_hash(file, ctx->pos); 501 } 502 503 /* 504 * If there are any leftover names on the hash collision 505 * chain, return them first. 506 */ 507 if (info->extra_fname) { 508 if (call_filldir(file, ctx, info->extra_fname)) 509 goto finished; 510 info->extra_fname = NULL; 511 goto next_node; 512 } else if (!info->curr_node) 513 info->curr_node = rb_first(&info->root); 514 515 while (1) { 516 /* 517 * Fill the rbtree if we have no more entries, 518 * or the inode has changed since we last read in the 519 * cached entries. 520 */ 521 if ((!info->curr_node) || 522 (file->f_version != inode->i_version)) { 523 info->curr_node = NULL; 524 free_rb_tree_fname(&info->root); 525 file->f_version = inode->i_version; 526 ret = ext4_htree_fill_tree(file, info->curr_hash, 527 info->curr_minor_hash, 528 &info->next_hash); 529 if (ret < 0) 530 return ret; 531 if (ret == 0) { 532 ctx->pos = ext4_get_htree_eof(file); 533 break; 534 } 535 info->curr_node = rb_first(&info->root); 536 } 537 538 fname = rb_entry(info->curr_node, struct fname, rb_hash); 539 info->curr_hash = fname->hash; 540 info->curr_minor_hash = fname->minor_hash; 541 if (call_filldir(file, ctx, fname)) 542 break; 543 next_node: 544 info->curr_node = rb_next(info->curr_node); 545 if (info->curr_node) { 546 fname = rb_entry(info->curr_node, struct fname, 547 rb_hash); 548 info->curr_hash = fname->hash; 549 info->curr_minor_hash = fname->minor_hash; 550 } else { 551 if (info->next_hash == ~0) { 552 ctx->pos = ext4_get_htree_eof(file); 553 break; 554 } 555 info->curr_hash = info->next_hash; 556 info->curr_minor_hash = 0; 557 } 558 } 559 finished: 560 info->last_pos = ctx->pos; 561 return 0; 562 } 563 564 static int ext4_release_dir(struct inode *inode, struct file *filp) 565 { 566 if (filp->private_data) 567 ext4_htree_free_dir_info(filp->private_data); 568 569 return 0; 570 } 571 572 int ext4_check_all_de(struct inode *dir, struct buffer_head *bh, void *buf, 573 int buf_size) 574 { 575 struct ext4_dir_entry_2 *de; 576 int nlen, rlen; 577 unsigned int offset = 0; 578 char *top; 579 580 de = (struct ext4_dir_entry_2 *)buf; 581 top = buf + buf_size; 582 while ((char *) de < top) { 583 if (ext4_check_dir_entry(dir, NULL, de, bh, 584 buf, buf_size, offset)) 585 return -EIO; 586 nlen = EXT4_DIR_REC_LEN(de->name_len); 587 rlen = ext4_rec_len_from_disk(de->rec_len, buf_size); 588 de = (struct ext4_dir_entry_2 *)((char *)de + rlen); 589 offset += rlen; 590 } 591 if ((char *) de > top) 592 return -EIO; 593 594 return 0; 595 } 596 597 const struct file_operations ext4_dir_operations = { 598 .llseek = ext4_dir_llseek, 599 .read = generic_read_dir, 600 .iterate = ext4_readdir, 601 .unlocked_ioctl = ext4_ioctl, 602 #ifdef CONFIG_COMPAT 603 .compat_ioctl = ext4_compat_ioctl, 604 #endif 605 .fsync = ext4_sync_file, 606 .release = ext4_release_dir, 607 }; 608