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