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 31 static unsigned char ext4_filetype_table[] = { 32 DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK, DT_FIFO, DT_SOCK, DT_LNK 33 }; 34 35 static int ext4_readdir(struct file *, void *, filldir_t); 36 static int ext4_dx_readdir(struct file *filp, 37 void *dirent, filldir_t filldir); 38 static int ext4_release_dir(struct inode *inode, 39 struct file *filp); 40 41 const struct file_operations ext4_dir_operations = { 42 .llseek = ext4_llseek, 43 .read = generic_read_dir, 44 .readdir = ext4_readdir, /* we take BKL. needed?*/ 45 .unlocked_ioctl = ext4_ioctl, 46 #ifdef CONFIG_COMPAT 47 .compat_ioctl = ext4_compat_ioctl, 48 #endif 49 .fsync = ext4_sync_file, 50 .release = ext4_release_dir, 51 }; 52 53 54 static unsigned char get_dtype(struct super_block *sb, int filetype) 55 { 56 if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FILETYPE) || 57 (filetype >= EXT4_FT_MAX)) 58 return DT_UNKNOWN; 59 60 return (ext4_filetype_table[filetype]); 61 } 62 63 /* 64 * Return 0 if the directory entry is OK, and 1 if there is a problem 65 * 66 * Note: this is the opposite of what ext2 and ext3 historically returned... 67 */ 68 int __ext4_check_dir_entry(const char *function, unsigned int line, 69 struct inode *dir, struct file *filp, 70 struct ext4_dir_entry_2 *de, 71 struct buffer_head *bh, 72 unsigned int offset) 73 { 74 const char *error_msg = NULL; 75 const int rlen = ext4_rec_len_from_disk(de->rec_len, 76 dir->i_sb->s_blocksize); 77 78 if (unlikely(rlen < EXT4_DIR_REC_LEN(1))) 79 error_msg = "rec_len is smaller than minimal"; 80 else if (unlikely(rlen % 4 != 0)) 81 error_msg = "rec_len % 4 != 0"; 82 else if (unlikely(rlen < EXT4_DIR_REC_LEN(de->name_len))) 83 error_msg = "rec_len is too small for name_len"; 84 else if (unlikely(((char *) de - bh->b_data) + rlen > 85 dir->i_sb->s_blocksize)) 86 error_msg = "directory entry across blocks"; 87 else if (unlikely(le32_to_cpu(de->inode) > 88 le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count))) 89 error_msg = "inode out of bounds"; 90 else 91 return 0; 92 93 if (filp) 94 ext4_error_file(filp, function, line, bh ? bh->b_blocknr : 0, 95 "bad entry in directory: %s - offset=%u(%u), " 96 "inode=%u, rec_len=%d, name_len=%d", 97 error_msg, (unsigned) (offset%bh->b_size), 98 offset, le32_to_cpu(de->inode), 99 rlen, de->name_len); 100 else 101 ext4_error_inode(dir, function, line, bh ? bh->b_blocknr : 0, 102 "bad entry in directory: %s - offset=%u(%u), " 103 "inode=%u, rec_len=%d, name_len=%d", 104 error_msg, (unsigned) (offset%bh->b_size), 105 offset, le32_to_cpu(de->inode), 106 rlen, de->name_len); 107 108 return 1; 109 } 110 111 static int ext4_readdir(struct file *filp, 112 void *dirent, filldir_t filldir) 113 { 114 int error = 0; 115 unsigned int offset; 116 int i, stored; 117 struct ext4_dir_entry_2 *de; 118 struct super_block *sb; 119 int err; 120 struct inode *inode = filp->f_path.dentry->d_inode; 121 int ret = 0; 122 int dir_has_error = 0; 123 124 sb = inode->i_sb; 125 126 if (EXT4_HAS_COMPAT_FEATURE(inode->i_sb, 127 EXT4_FEATURE_COMPAT_DIR_INDEX) && 128 ((ext4_test_inode_flag(inode, EXT4_INODE_INDEX)) || 129 ((inode->i_size >> sb->s_blocksize_bits) == 1))) { 130 err = ext4_dx_readdir(filp, dirent, filldir); 131 if (err != ERR_BAD_DX_DIR) { 132 ret = err; 133 goto out; 134 } 135 /* 136 * We don't set the inode dirty flag since it's not 137 * critical that it get flushed back to the disk. 138 */ 139 ext4_clear_inode_flag(filp->f_path.dentry->d_inode, 140 EXT4_INODE_INDEX); 141 } 142 stored = 0; 143 offset = filp->f_pos & (sb->s_blocksize - 1); 144 145 while (!error && !stored && filp->f_pos < inode->i_size) { 146 struct ext4_map_blocks map; 147 struct buffer_head *bh = NULL; 148 149 map.m_lblk = filp->f_pos >> EXT4_BLOCK_SIZE_BITS(sb); 150 map.m_len = 1; 151 err = ext4_map_blocks(NULL, inode, &map, 0); 152 if (err > 0) { 153 pgoff_t index = map.m_pblk >> 154 (PAGE_CACHE_SHIFT - inode->i_blkbits); 155 if (!ra_has_index(&filp->f_ra, index)) 156 page_cache_sync_readahead( 157 sb->s_bdev->bd_inode->i_mapping, 158 &filp->f_ra, filp, 159 index, 1); 160 filp->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT; 161 bh = ext4_bread(NULL, inode, map.m_lblk, 0, &err); 162 } 163 164 /* 165 * We ignore I/O errors on directories so users have a chance 166 * of recovering data when there's a bad sector 167 */ 168 if (!bh) { 169 if (!dir_has_error) { 170 EXT4_ERROR_FILE(filp, 0, 171 "directory contains a " 172 "hole at offset %llu", 173 (unsigned long long) filp->f_pos); 174 dir_has_error = 1; 175 } 176 /* corrupt size? Maybe no more blocks to read */ 177 if (filp->f_pos > inode->i_blocks << 9) 178 break; 179 filp->f_pos += sb->s_blocksize - offset; 180 continue; 181 } 182 183 revalidate: 184 /* If the dir block has changed since the last call to 185 * readdir(2), then we might be pointing to an invalid 186 * dirent right now. Scan from the start of the block 187 * to make sure. */ 188 if (filp->f_version != inode->i_version) { 189 for (i = 0; i < sb->s_blocksize && i < offset; ) { 190 de = (struct ext4_dir_entry_2 *) 191 (bh->b_data + i); 192 /* It's too expensive to do a full 193 * dirent test each time round this 194 * loop, but we do have to test at 195 * least that it is non-zero. A 196 * failure will be detected in the 197 * dirent test below. */ 198 if (ext4_rec_len_from_disk(de->rec_len, 199 sb->s_blocksize) < EXT4_DIR_REC_LEN(1)) 200 break; 201 i += ext4_rec_len_from_disk(de->rec_len, 202 sb->s_blocksize); 203 } 204 offset = i; 205 filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1)) 206 | offset; 207 filp->f_version = inode->i_version; 208 } 209 210 while (!error && filp->f_pos < inode->i_size 211 && offset < sb->s_blocksize) { 212 de = (struct ext4_dir_entry_2 *) (bh->b_data + offset); 213 if (ext4_check_dir_entry(inode, filp, de, 214 bh, offset)) { 215 /* 216 * On error, skip the f_pos to the next block 217 */ 218 filp->f_pos = (filp->f_pos | 219 (sb->s_blocksize - 1)) + 1; 220 brelse(bh); 221 ret = stored; 222 goto out; 223 } 224 offset += ext4_rec_len_from_disk(de->rec_len, 225 sb->s_blocksize); 226 if (le32_to_cpu(de->inode)) { 227 /* We might block in the next section 228 * if the data destination is 229 * currently swapped out. So, use a 230 * version stamp to detect whether or 231 * not the directory has been modified 232 * during the copy operation. 233 */ 234 u64 version = filp->f_version; 235 236 error = filldir(dirent, de->name, 237 de->name_len, 238 filp->f_pos, 239 le32_to_cpu(de->inode), 240 get_dtype(sb, de->file_type)); 241 if (error) 242 break; 243 if (version != filp->f_version) 244 goto revalidate; 245 stored++; 246 } 247 filp->f_pos += ext4_rec_len_from_disk(de->rec_len, 248 sb->s_blocksize); 249 } 250 offset = 0; 251 brelse(bh); 252 } 253 out: 254 return ret; 255 } 256 257 /* 258 * These functions convert from the major/minor hash to an f_pos 259 * value. 260 * 261 * Currently we only use major hash numer. This is unfortunate, but 262 * on 32-bit machines, the same VFS interface is used for lseek and 263 * llseek, so if we use the 64 bit offset, then the 32-bit versions of 264 * lseek/telldir/seekdir will blow out spectacularly, and from within 265 * the ext2 low-level routine, we don't know if we're being called by 266 * a 64-bit version of the system call or the 32-bit version of the 267 * system call. Worse yet, NFSv2 only allows for a 32-bit readdir 268 * cookie. Sigh. 269 */ 270 #define hash2pos(major, minor) (major >> 1) 271 #define pos2maj_hash(pos) ((pos << 1) & 0xffffffff) 272 #define pos2min_hash(pos) (0) 273 274 /* 275 * This structure holds the nodes of the red-black tree used to store 276 * the directory entry in hash order. 277 */ 278 struct fname { 279 __u32 hash; 280 __u32 minor_hash; 281 struct rb_node rb_hash; 282 struct fname *next; 283 __u32 inode; 284 __u8 name_len; 285 __u8 file_type; 286 char name[0]; 287 }; 288 289 /* 290 * This functoin implements a non-recursive way of freeing all of the 291 * nodes in the red-black tree. 292 */ 293 static void free_rb_tree_fname(struct rb_root *root) 294 { 295 struct rb_node *n = root->rb_node; 296 struct rb_node *parent; 297 struct fname *fname; 298 299 while (n) { 300 /* Do the node's children first */ 301 if (n->rb_left) { 302 n = n->rb_left; 303 continue; 304 } 305 if (n->rb_right) { 306 n = n->rb_right; 307 continue; 308 } 309 /* 310 * The node has no children; free it, and then zero 311 * out parent's link to it. Finally go to the 312 * beginning of the loop and try to free the parent 313 * node. 314 */ 315 parent = rb_parent(n); 316 fname = rb_entry(n, struct fname, rb_hash); 317 while (fname) { 318 struct fname *old = fname; 319 fname = fname->next; 320 kfree(old); 321 } 322 if (!parent) 323 *root = RB_ROOT; 324 else if (parent->rb_left == n) 325 parent->rb_left = NULL; 326 else if (parent->rb_right == n) 327 parent->rb_right = NULL; 328 n = parent; 329 } 330 } 331 332 333 static struct dir_private_info *ext4_htree_create_dir_info(loff_t pos) 334 { 335 struct dir_private_info *p; 336 337 p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL); 338 if (!p) 339 return NULL; 340 p->curr_hash = pos2maj_hash(pos); 341 p->curr_minor_hash = pos2min_hash(pos); 342 return p; 343 } 344 345 void ext4_htree_free_dir_info(struct dir_private_info *p) 346 { 347 free_rb_tree_fname(&p->root); 348 kfree(p); 349 } 350 351 /* 352 * Given a directory entry, enter it into the fname rb tree. 353 */ 354 int ext4_htree_store_dirent(struct file *dir_file, __u32 hash, 355 __u32 minor_hash, 356 struct ext4_dir_entry_2 *dirent) 357 { 358 struct rb_node **p, *parent = NULL; 359 struct fname *fname, *new_fn; 360 struct dir_private_info *info; 361 int len; 362 363 info = dir_file->private_data; 364 p = &info->root.rb_node; 365 366 /* Create and allocate the fname structure */ 367 len = sizeof(struct fname) + dirent->name_len + 1; 368 new_fn = kzalloc(len, GFP_KERNEL); 369 if (!new_fn) 370 return -ENOMEM; 371 new_fn->hash = hash; 372 new_fn->minor_hash = minor_hash; 373 new_fn->inode = le32_to_cpu(dirent->inode); 374 new_fn->name_len = dirent->name_len; 375 new_fn->file_type = dirent->file_type; 376 memcpy(new_fn->name, dirent->name, dirent->name_len); 377 new_fn->name[dirent->name_len] = 0; 378 379 while (*p) { 380 parent = *p; 381 fname = rb_entry(parent, struct fname, rb_hash); 382 383 /* 384 * If the hash and minor hash match up, then we put 385 * them on a linked list. This rarely happens... 386 */ 387 if ((new_fn->hash == fname->hash) && 388 (new_fn->minor_hash == fname->minor_hash)) { 389 new_fn->next = fname->next; 390 fname->next = new_fn; 391 return 0; 392 } 393 394 if (new_fn->hash < fname->hash) 395 p = &(*p)->rb_left; 396 else if (new_fn->hash > fname->hash) 397 p = &(*p)->rb_right; 398 else if (new_fn->minor_hash < fname->minor_hash) 399 p = &(*p)->rb_left; 400 else /* if (new_fn->minor_hash > fname->minor_hash) */ 401 p = &(*p)->rb_right; 402 } 403 404 rb_link_node(&new_fn->rb_hash, parent, p); 405 rb_insert_color(&new_fn->rb_hash, &info->root); 406 return 0; 407 } 408 409 410 411 /* 412 * This is a helper function for ext4_dx_readdir. It calls filldir 413 * for all entres on the fname linked list. (Normally there is only 414 * one entry on the linked list, unless there are 62 bit hash collisions.) 415 */ 416 static int call_filldir(struct file *filp, void *dirent, 417 filldir_t filldir, struct fname *fname) 418 { 419 struct dir_private_info *info = filp->private_data; 420 loff_t curr_pos; 421 struct inode *inode = filp->f_path.dentry->d_inode; 422 struct super_block *sb; 423 int error; 424 425 sb = inode->i_sb; 426 427 if (!fname) { 428 printk(KERN_ERR "EXT4-fs: call_filldir: called with " 429 "null fname?!?\n"); 430 return 0; 431 } 432 curr_pos = hash2pos(fname->hash, fname->minor_hash); 433 while (fname) { 434 error = filldir(dirent, fname->name, 435 fname->name_len, curr_pos, 436 fname->inode, 437 get_dtype(sb, fname->file_type)); 438 if (error) { 439 filp->f_pos = curr_pos; 440 info->extra_fname = fname; 441 return error; 442 } 443 fname = fname->next; 444 } 445 return 0; 446 } 447 448 static int ext4_dx_readdir(struct file *filp, 449 void *dirent, filldir_t filldir) 450 { 451 struct dir_private_info *info = filp->private_data; 452 struct inode *inode = filp->f_path.dentry->d_inode; 453 struct fname *fname; 454 int ret; 455 456 if (!info) { 457 info = ext4_htree_create_dir_info(filp->f_pos); 458 if (!info) 459 return -ENOMEM; 460 filp->private_data = info; 461 } 462 463 if (filp->f_pos == EXT4_HTREE_EOF) 464 return 0; /* EOF */ 465 466 /* Some one has messed with f_pos; reset the world */ 467 if (info->last_pos != filp->f_pos) { 468 free_rb_tree_fname(&info->root); 469 info->curr_node = NULL; 470 info->extra_fname = NULL; 471 info->curr_hash = pos2maj_hash(filp->f_pos); 472 info->curr_minor_hash = pos2min_hash(filp->f_pos); 473 } 474 475 /* 476 * If there are any leftover names on the hash collision 477 * chain, return them first. 478 */ 479 if (info->extra_fname) { 480 if (call_filldir(filp, dirent, filldir, info->extra_fname)) 481 goto finished; 482 info->extra_fname = NULL; 483 goto next_node; 484 } else if (!info->curr_node) 485 info->curr_node = rb_first(&info->root); 486 487 while (1) { 488 /* 489 * Fill the rbtree if we have no more entries, 490 * or the inode has changed since we last read in the 491 * cached entries. 492 */ 493 if ((!info->curr_node) || 494 (filp->f_version != inode->i_version)) { 495 info->curr_node = NULL; 496 free_rb_tree_fname(&info->root); 497 filp->f_version = inode->i_version; 498 ret = ext4_htree_fill_tree(filp, info->curr_hash, 499 info->curr_minor_hash, 500 &info->next_hash); 501 if (ret < 0) 502 return ret; 503 if (ret == 0) { 504 filp->f_pos = EXT4_HTREE_EOF; 505 break; 506 } 507 info->curr_node = rb_first(&info->root); 508 } 509 510 fname = rb_entry(info->curr_node, struct fname, rb_hash); 511 info->curr_hash = fname->hash; 512 info->curr_minor_hash = fname->minor_hash; 513 if (call_filldir(filp, dirent, filldir, fname)) 514 break; 515 next_node: 516 info->curr_node = rb_next(info->curr_node); 517 if (info->curr_node) { 518 fname = rb_entry(info->curr_node, struct fname, 519 rb_hash); 520 info->curr_hash = fname->hash; 521 info->curr_minor_hash = fname->minor_hash; 522 } else { 523 if (info->next_hash == ~0) { 524 filp->f_pos = EXT4_HTREE_EOF; 525 break; 526 } 527 info->curr_hash = info->next_hash; 528 info->curr_minor_hash = 0; 529 } 530 } 531 finished: 532 info->last_pos = filp->f_pos; 533 return 0; 534 } 535 536 static int ext4_release_dir(struct inode *inode, struct file *filp) 537 { 538 if (filp->private_data) 539 ext4_htree_free_dir_info(filp->private_data); 540 541 return 0; 542 } 543