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