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 = generic_file_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 int ext4_check_dir_entry(const char *function, struct inode *dir, 65 struct ext4_dir_entry_2 *de, 66 struct buffer_head *bh, 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 (rlen < EXT4_DIR_REC_LEN(1)) 74 error_msg = "rec_len is smaller than minimal"; 75 else if (rlen % 4 != 0) 76 error_msg = "rec_len % 4 != 0"; 77 else if (rlen < EXT4_DIR_REC_LEN(de->name_len)) 78 error_msg = "rec_len is too small for name_len"; 79 else if (((char *) de - bh->b_data) + rlen > dir->i_sb->s_blocksize) 80 error_msg = "directory entry across blocks"; 81 else if (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 85 if (error_msg != NULL) 86 __ext4_error(dir->i_sb, function, 87 "bad entry in directory #%lu: %s - block=%llu" 88 "offset=%u(%u), inode=%u, rec_len=%d, name_len=%d", 89 dir->i_ino, error_msg, 90 (unsigned long long) bh->b_blocknr, 91 (unsigned) (offset%bh->b_size), offset, 92 le32_to_cpu(de->inode), 93 rlen, de->name_len); 94 return error_msg == NULL ? 1 : 0; 95 } 96 97 static int ext4_readdir(struct file *filp, 98 void *dirent, filldir_t filldir) 99 { 100 int error = 0; 101 unsigned int offset; 102 int i, stored; 103 struct ext4_dir_entry_2 *de; 104 struct super_block *sb; 105 int err; 106 struct inode *inode = filp->f_path.dentry->d_inode; 107 int ret = 0; 108 int dir_has_error = 0; 109 110 sb = inode->i_sb; 111 112 if (EXT4_HAS_COMPAT_FEATURE(inode->i_sb, 113 EXT4_FEATURE_COMPAT_DIR_INDEX) && 114 ((EXT4_I(inode)->i_flags & EXT4_INDEX_FL) || 115 ((inode->i_size >> sb->s_blocksize_bits) == 1))) { 116 err = ext4_dx_readdir(filp, dirent, filldir); 117 if (err != ERR_BAD_DX_DIR) { 118 ret = err; 119 goto out; 120 } 121 /* 122 * We don't set the inode dirty flag since it's not 123 * critical that it get flushed back to the disk. 124 */ 125 EXT4_I(filp->f_path.dentry->d_inode)->i_flags &= ~EXT4_INDEX_FL; 126 } 127 stored = 0; 128 offset = filp->f_pos & (sb->s_blocksize - 1); 129 130 while (!error && !stored && filp->f_pos < inode->i_size) { 131 ext4_lblk_t blk = filp->f_pos >> EXT4_BLOCK_SIZE_BITS(sb); 132 struct buffer_head map_bh; 133 struct buffer_head *bh = NULL; 134 135 map_bh.b_state = 0; 136 err = ext4_get_blocks(NULL, inode, blk, 1, &map_bh, 0); 137 if (err > 0) { 138 pgoff_t index = map_bh.b_blocknr >> 139 (PAGE_CACHE_SHIFT - inode->i_blkbits); 140 if (!ra_has_index(&filp->f_ra, index)) 141 page_cache_sync_readahead( 142 sb->s_bdev->bd_inode->i_mapping, 143 &filp->f_ra, filp, 144 index, 1); 145 filp->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT; 146 bh = ext4_bread(NULL, inode, blk, 0, &err); 147 } 148 149 /* 150 * We ignore I/O errors on directories so users have a chance 151 * of recovering data when there's a bad sector 152 */ 153 if (!bh) { 154 if (!dir_has_error) { 155 ext4_error(sb, "directory #%lu " 156 "contains a hole at offset %Lu", 157 inode->i_ino, 158 (unsigned long long) filp->f_pos); 159 dir_has_error = 1; 160 } 161 /* corrupt size? Maybe no more blocks to read */ 162 if (filp->f_pos > inode->i_blocks << 9) 163 break; 164 filp->f_pos += sb->s_blocksize - offset; 165 continue; 166 } 167 168 revalidate: 169 /* If the dir block has changed since the last call to 170 * readdir(2), then we might be pointing to an invalid 171 * dirent right now. Scan from the start of the block 172 * to make sure. */ 173 if (filp->f_version != inode->i_version) { 174 for (i = 0; i < sb->s_blocksize && i < offset; ) { 175 de = (struct ext4_dir_entry_2 *) 176 (bh->b_data + i); 177 /* It's too expensive to do a full 178 * dirent test each time round this 179 * loop, but we do have to test at 180 * least that it is non-zero. A 181 * failure will be detected in the 182 * dirent test below. */ 183 if (ext4_rec_len_from_disk(de->rec_len, 184 sb->s_blocksize) < EXT4_DIR_REC_LEN(1)) 185 break; 186 i += ext4_rec_len_from_disk(de->rec_len, 187 sb->s_blocksize); 188 } 189 offset = i; 190 filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1)) 191 | offset; 192 filp->f_version = inode->i_version; 193 } 194 195 while (!error && filp->f_pos < inode->i_size 196 && offset < sb->s_blocksize) { 197 de = (struct ext4_dir_entry_2 *) (bh->b_data + offset); 198 if (!ext4_check_dir_entry("ext4_readdir", inode, de, 199 bh, offset)) { 200 /* 201 * On error, skip the f_pos to the next block 202 */ 203 filp->f_pos = (filp->f_pos | 204 (sb->s_blocksize - 1)) + 1; 205 brelse(bh); 206 ret = stored; 207 goto out; 208 } 209 offset += ext4_rec_len_from_disk(de->rec_len, 210 sb->s_blocksize); 211 if (le32_to_cpu(de->inode)) { 212 /* We might block in the next section 213 * if the data destination is 214 * currently swapped out. So, use a 215 * version stamp to detect whether or 216 * not the directory has been modified 217 * during the copy operation. 218 */ 219 u64 version = filp->f_version; 220 221 error = filldir(dirent, de->name, 222 de->name_len, 223 filp->f_pos, 224 le32_to_cpu(de->inode), 225 get_dtype(sb, de->file_type)); 226 if (error) 227 break; 228 if (version != filp->f_version) 229 goto revalidate; 230 stored++; 231 } 232 filp->f_pos += ext4_rec_len_from_disk(de->rec_len, 233 sb->s_blocksize); 234 } 235 offset = 0; 236 brelse(bh); 237 } 238 out: 239 return ret; 240 } 241 242 /* 243 * These functions convert from the major/minor hash to an f_pos 244 * value. 245 * 246 * Currently we only use major hash numer. This is unfortunate, but 247 * on 32-bit machines, the same VFS interface is used for lseek and 248 * llseek, so if we use the 64 bit offset, then the 32-bit versions of 249 * lseek/telldir/seekdir will blow out spectacularly, and from within 250 * the ext2 low-level routine, we don't know if we're being called by 251 * a 64-bit version of the system call or the 32-bit version of the 252 * system call. Worse yet, NFSv2 only allows for a 32-bit readdir 253 * cookie. Sigh. 254 */ 255 #define hash2pos(major, minor) (major >> 1) 256 #define pos2maj_hash(pos) ((pos << 1) & 0xffffffff) 257 #define pos2min_hash(pos) (0) 258 259 /* 260 * This structure holds the nodes of the red-black tree used to store 261 * the directory entry in hash order. 262 */ 263 struct fname { 264 __u32 hash; 265 __u32 minor_hash; 266 struct rb_node rb_hash; 267 struct fname *next; 268 __u32 inode; 269 __u8 name_len; 270 __u8 file_type; 271 char name[0]; 272 }; 273 274 /* 275 * This functoin implements a non-recursive way of freeing all of the 276 * nodes in the red-black tree. 277 */ 278 static void free_rb_tree_fname(struct rb_root *root) 279 { 280 struct rb_node *n = root->rb_node; 281 struct rb_node *parent; 282 struct fname *fname; 283 284 while (n) { 285 /* Do the node's children first */ 286 if (n->rb_left) { 287 n = n->rb_left; 288 continue; 289 } 290 if (n->rb_right) { 291 n = n->rb_right; 292 continue; 293 } 294 /* 295 * The node has no children; free it, and then zero 296 * out parent's link to it. Finally go to the 297 * beginning of the loop and try to free the parent 298 * node. 299 */ 300 parent = rb_parent(n); 301 fname = rb_entry(n, struct fname, rb_hash); 302 while (fname) { 303 struct fname *old = fname; 304 fname = fname->next; 305 kfree(old); 306 } 307 if (!parent) 308 *root = RB_ROOT; 309 else if (parent->rb_left == n) 310 parent->rb_left = NULL; 311 else if (parent->rb_right == n) 312 parent->rb_right = NULL; 313 n = parent; 314 } 315 } 316 317 318 static struct dir_private_info *ext4_htree_create_dir_info(loff_t pos) 319 { 320 struct dir_private_info *p; 321 322 p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL); 323 if (!p) 324 return NULL; 325 p->curr_hash = pos2maj_hash(pos); 326 p->curr_minor_hash = pos2min_hash(pos); 327 return p; 328 } 329 330 void ext4_htree_free_dir_info(struct dir_private_info *p) 331 { 332 free_rb_tree_fname(&p->root); 333 kfree(p); 334 } 335 336 /* 337 * Given a directory entry, enter it into the fname rb tree. 338 */ 339 int ext4_htree_store_dirent(struct file *dir_file, __u32 hash, 340 __u32 minor_hash, 341 struct ext4_dir_entry_2 *dirent) 342 { 343 struct rb_node **p, *parent = NULL; 344 struct fname *fname, *new_fn; 345 struct dir_private_info *info; 346 int len; 347 348 info = (struct dir_private_info *) dir_file->private_data; 349 p = &info->root.rb_node; 350 351 /* Create and allocate the fname structure */ 352 len = sizeof(struct fname) + dirent->name_len + 1; 353 new_fn = kzalloc(len, GFP_KERNEL); 354 if (!new_fn) 355 return -ENOMEM; 356 new_fn->hash = hash; 357 new_fn->minor_hash = minor_hash; 358 new_fn->inode = le32_to_cpu(dirent->inode); 359 new_fn->name_len = dirent->name_len; 360 new_fn->file_type = dirent->file_type; 361 memcpy(new_fn->name, dirent->name, dirent->name_len); 362 new_fn->name[dirent->name_len] = 0; 363 364 while (*p) { 365 parent = *p; 366 fname = rb_entry(parent, struct fname, rb_hash); 367 368 /* 369 * If the hash and minor hash match up, then we put 370 * them on a linked list. This rarely happens... 371 */ 372 if ((new_fn->hash == fname->hash) && 373 (new_fn->minor_hash == fname->minor_hash)) { 374 new_fn->next = fname->next; 375 fname->next = new_fn; 376 return 0; 377 } 378 379 if (new_fn->hash < fname->hash) 380 p = &(*p)->rb_left; 381 else if (new_fn->hash > fname->hash) 382 p = &(*p)->rb_right; 383 else if (new_fn->minor_hash < fname->minor_hash) 384 p = &(*p)->rb_left; 385 else /* if (new_fn->minor_hash > fname->minor_hash) */ 386 p = &(*p)->rb_right; 387 } 388 389 rb_link_node(&new_fn->rb_hash, parent, p); 390 rb_insert_color(&new_fn->rb_hash, &info->root); 391 return 0; 392 } 393 394 395 396 /* 397 * This is a helper function for ext4_dx_readdir. It calls filldir 398 * for all entres on the fname linked list. (Normally there is only 399 * one entry on the linked list, unless there are 62 bit hash collisions.) 400 */ 401 static int call_filldir(struct file *filp, void *dirent, 402 filldir_t filldir, struct fname *fname) 403 { 404 struct dir_private_info *info = filp->private_data; 405 loff_t curr_pos; 406 struct inode *inode = filp->f_path.dentry->d_inode; 407 struct super_block *sb; 408 int error; 409 410 sb = inode->i_sb; 411 412 if (!fname) { 413 printk(KERN_ERR "EXT4-fs: call_filldir: called with " 414 "null fname?!?\n"); 415 return 0; 416 } 417 curr_pos = hash2pos(fname->hash, fname->minor_hash); 418 while (fname) { 419 error = filldir(dirent, fname->name, 420 fname->name_len, curr_pos, 421 fname->inode, 422 get_dtype(sb, fname->file_type)); 423 if (error) { 424 filp->f_pos = curr_pos; 425 info->extra_fname = fname; 426 return error; 427 } 428 fname = fname->next; 429 } 430 return 0; 431 } 432 433 static int ext4_dx_readdir(struct file *filp, 434 void *dirent, filldir_t filldir) 435 { 436 struct dir_private_info *info = filp->private_data; 437 struct inode *inode = filp->f_path.dentry->d_inode; 438 struct fname *fname; 439 int ret; 440 441 if (!info) { 442 info = ext4_htree_create_dir_info(filp->f_pos); 443 if (!info) 444 return -ENOMEM; 445 filp->private_data = info; 446 } 447 448 if (filp->f_pos == EXT4_HTREE_EOF) 449 return 0; /* EOF */ 450 451 /* Some one has messed with f_pos; reset the world */ 452 if (info->last_pos != filp->f_pos) { 453 free_rb_tree_fname(&info->root); 454 info->curr_node = NULL; 455 info->extra_fname = NULL; 456 info->curr_hash = pos2maj_hash(filp->f_pos); 457 info->curr_minor_hash = pos2min_hash(filp->f_pos); 458 } 459 460 /* 461 * If there are any leftover names on the hash collision 462 * chain, return them first. 463 */ 464 if (info->extra_fname) { 465 if (call_filldir(filp, dirent, filldir, info->extra_fname)) 466 goto finished; 467 info->extra_fname = NULL; 468 goto next_node; 469 } else if (!info->curr_node) 470 info->curr_node = rb_first(&info->root); 471 472 while (1) { 473 /* 474 * Fill the rbtree if we have no more entries, 475 * or the inode has changed since we last read in the 476 * cached entries. 477 */ 478 if ((!info->curr_node) || 479 (filp->f_version != inode->i_version)) { 480 info->curr_node = NULL; 481 free_rb_tree_fname(&info->root); 482 filp->f_version = inode->i_version; 483 ret = ext4_htree_fill_tree(filp, info->curr_hash, 484 info->curr_minor_hash, 485 &info->next_hash); 486 if (ret < 0) 487 return ret; 488 if (ret == 0) { 489 filp->f_pos = EXT4_HTREE_EOF; 490 break; 491 } 492 info->curr_node = rb_first(&info->root); 493 } 494 495 fname = rb_entry(info->curr_node, struct fname, rb_hash); 496 info->curr_hash = fname->hash; 497 info->curr_minor_hash = fname->minor_hash; 498 if (call_filldir(filp, dirent, filldir, fname)) 499 break; 500 next_node: 501 info->curr_node = rb_next(info->curr_node); 502 if (info->curr_node) { 503 fname = rb_entry(info->curr_node, struct fname, 504 rb_hash); 505 info->curr_hash = fname->hash; 506 info->curr_minor_hash = fname->minor_hash; 507 } else { 508 if (info->next_hash == ~0) { 509 filp->f_pos = EXT4_HTREE_EOF; 510 break; 511 } 512 info->curr_hash = info->next_hash; 513 info->curr_minor_hash = 0; 514 } 515 } 516 finished: 517 info->last_pos = filp->f_pos; 518 return 0; 519 } 520 521 static int ext4_release_dir(struct inode *inode, struct file *filp) 522 { 523 if (filp->private_data) 524 ext4_htree_free_dir_info(filp->private_data); 525 526 return 0; 527 } 528