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 72 if (rlen < EXT4_DIR_REC_LEN(1)) 73 error_msg = "rec_len is smaller than minimal"; 74 else if (rlen % 4 != 0) 75 error_msg = "rec_len % 4 != 0"; 76 else if (rlen < EXT4_DIR_REC_LEN(de->name_len)) 77 error_msg = "rec_len is too small for name_len"; 78 else if (((char *) de - bh->b_data) + rlen > dir->i_sb->s_blocksize) 79 error_msg = "directory entry across blocks"; 80 else if (le32_to_cpu(de->inode) > 81 le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count)) 82 error_msg = "inode out of bounds"; 83 84 if (error_msg != NULL) 85 ext4_error(dir->i_sb, function, 86 "bad entry in directory #%lu: %s - " 87 "offset=%u, inode=%u, rec_len=%d, name_len=%d", 88 dir->i_ino, error_msg, offset, 89 le32_to_cpu(de->inode), 90 rlen, de->name_len); 91 return error_msg == NULL ? 1 : 0; 92 } 93 94 static int ext4_readdir(struct file *filp, 95 void *dirent, filldir_t filldir) 96 { 97 int error = 0; 98 unsigned int offset; 99 int i, stored; 100 struct ext4_dir_entry_2 *de; 101 struct super_block *sb; 102 int err; 103 struct inode *inode = filp->f_path.dentry->d_inode; 104 int ret = 0; 105 int dir_has_error = 0; 106 107 sb = inode->i_sb; 108 109 if (EXT4_HAS_COMPAT_FEATURE(inode->i_sb, 110 EXT4_FEATURE_COMPAT_DIR_INDEX) && 111 ((EXT4_I(inode)->i_flags & EXT4_INDEX_FL) || 112 ((inode->i_size >> sb->s_blocksize_bits) == 1))) { 113 err = ext4_dx_readdir(filp, dirent, filldir); 114 if (err != ERR_BAD_DX_DIR) { 115 ret = err; 116 goto out; 117 } 118 /* 119 * We don't set the inode dirty flag since it's not 120 * critical that it get flushed back to the disk. 121 */ 122 EXT4_I(filp->f_path.dentry->d_inode)->i_flags &= ~EXT4_INDEX_FL; 123 } 124 stored = 0; 125 offset = filp->f_pos & (sb->s_blocksize - 1); 126 127 while (!error && !stored && filp->f_pos < inode->i_size) { 128 ext4_lblk_t blk = filp->f_pos >> EXT4_BLOCK_SIZE_BITS(sb); 129 struct buffer_head map_bh; 130 struct buffer_head *bh = NULL; 131 132 map_bh.b_state = 0; 133 err = ext4_get_blocks_wrap(NULL, inode, blk, 1, &map_bh, 134 0, 0, 0); 135 if (err > 0) { 136 pgoff_t index = map_bh.b_blocknr >> 137 (PAGE_CACHE_SHIFT - inode->i_blkbits); 138 if (!ra_has_index(&filp->f_ra, index)) 139 page_cache_sync_readahead( 140 sb->s_bdev->bd_inode->i_mapping, 141 &filp->f_ra, filp, 142 index, 1); 143 filp->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT; 144 bh = ext4_bread(NULL, inode, blk, 0, &err); 145 } 146 147 /* 148 * We ignore I/O errors on directories so users have a chance 149 * of recovering data when there's a bad sector 150 */ 151 if (!bh) { 152 if (!dir_has_error) { 153 ext4_error(sb, __func__, "directory #%lu " 154 "contains a hole at offset %Lu", 155 inode->i_ino, 156 (unsigned long long) filp->f_pos); 157 dir_has_error = 1; 158 } 159 /* corrupt size? Maybe no more blocks to read */ 160 if (filp->f_pos > inode->i_blocks << 9) 161 break; 162 filp->f_pos += sb->s_blocksize - offset; 163 continue; 164 } 165 166 revalidate: 167 /* If the dir block has changed since the last call to 168 * readdir(2), then we might be pointing to an invalid 169 * dirent right now. Scan from the start of the block 170 * to make sure. */ 171 if (filp->f_version != inode->i_version) { 172 for (i = 0; i < sb->s_blocksize && i < offset; ) { 173 de = (struct ext4_dir_entry_2 *) 174 (bh->b_data + i); 175 /* It's too expensive to do a full 176 * dirent test each time round this 177 * loop, but we do have to test at 178 * least that it is non-zero. A 179 * failure will be detected in the 180 * dirent test below. */ 181 if (ext4_rec_len_from_disk(de->rec_len) 182 < EXT4_DIR_REC_LEN(1)) 183 break; 184 i += ext4_rec_len_from_disk(de->rec_len); 185 } 186 offset = i; 187 filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1)) 188 | offset; 189 filp->f_version = inode->i_version; 190 } 191 192 while (!error && filp->f_pos < inode->i_size 193 && offset < sb->s_blocksize) { 194 de = (struct ext4_dir_entry_2 *) (bh->b_data + offset); 195 if (!ext4_check_dir_entry("ext4_readdir", inode, de, 196 bh, offset)) { 197 /* 198 * On error, skip the f_pos to the next block 199 */ 200 filp->f_pos = (filp->f_pos | 201 (sb->s_blocksize - 1)) + 1; 202 brelse(bh); 203 ret = stored; 204 goto out; 205 } 206 offset += ext4_rec_len_from_disk(de->rec_len); 207 if (le32_to_cpu(de->inode)) { 208 /* We might block in the next section 209 * if the data destination is 210 * currently swapped out. So, use a 211 * version stamp to detect whether or 212 * not the directory has been modified 213 * during the copy operation. 214 */ 215 u64 version = filp->f_version; 216 217 error = filldir(dirent, de->name, 218 de->name_len, 219 filp->f_pos, 220 le32_to_cpu(de->inode), 221 get_dtype(sb, de->file_type)); 222 if (error) 223 break; 224 if (version != filp->f_version) 225 goto revalidate; 226 stored++; 227 } 228 filp->f_pos += ext4_rec_len_from_disk(de->rec_len); 229 } 230 offset = 0; 231 brelse(bh); 232 } 233 out: 234 return ret; 235 } 236 237 /* 238 * These functions convert from the major/minor hash to an f_pos 239 * value. 240 * 241 * Currently we only use major hash numer. This is unfortunate, but 242 * on 32-bit machines, the same VFS interface is used for lseek and 243 * llseek, so if we use the 64 bit offset, then the 32-bit versions of 244 * lseek/telldir/seekdir will blow out spectacularly, and from within 245 * the ext2 low-level routine, we don't know if we're being called by 246 * a 64-bit version of the system call or the 32-bit version of the 247 * system call. Worse yet, NFSv2 only allows for a 32-bit readdir 248 * cookie. Sigh. 249 */ 250 #define hash2pos(major, minor) (major >> 1) 251 #define pos2maj_hash(pos) ((pos << 1) & 0xffffffff) 252 #define pos2min_hash(pos) (0) 253 254 /* 255 * This structure holds the nodes of the red-black tree used to store 256 * the directory entry in hash order. 257 */ 258 struct fname { 259 __u32 hash; 260 __u32 minor_hash; 261 struct rb_node rb_hash; 262 struct fname *next; 263 __u32 inode; 264 __u8 name_len; 265 __u8 file_type; 266 char name[0]; 267 }; 268 269 /* 270 * This functoin implements a non-recursive way of freeing all of the 271 * nodes in the red-black tree. 272 */ 273 static void free_rb_tree_fname(struct rb_root *root) 274 { 275 struct rb_node *n = root->rb_node; 276 struct rb_node *parent; 277 struct fname *fname; 278 279 while (n) { 280 /* Do the node's children first */ 281 if (n->rb_left) { 282 n = n->rb_left; 283 continue; 284 } 285 if (n->rb_right) { 286 n = n->rb_right; 287 continue; 288 } 289 /* 290 * The node has no children; free it, and then zero 291 * out parent's link to it. Finally go to the 292 * beginning of the loop and try to free the parent 293 * node. 294 */ 295 parent = rb_parent(n); 296 fname = rb_entry(n, struct fname, rb_hash); 297 while (fname) { 298 struct fname *old = fname; 299 fname = fname->next; 300 kfree(old); 301 } 302 if (!parent) 303 root->rb_node = NULL; 304 else if (parent->rb_left == n) 305 parent->rb_left = NULL; 306 else if (parent->rb_right == n) 307 parent->rb_right = NULL; 308 n = parent; 309 } 310 } 311 312 313 static struct dir_private_info *ext4_htree_create_dir_info(loff_t pos) 314 { 315 struct dir_private_info *p; 316 317 p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL); 318 if (!p) 319 return NULL; 320 p->curr_hash = pos2maj_hash(pos); 321 p->curr_minor_hash = pos2min_hash(pos); 322 return p; 323 } 324 325 void ext4_htree_free_dir_info(struct dir_private_info *p) 326 { 327 free_rb_tree_fname(&p->root); 328 kfree(p); 329 } 330 331 /* 332 * Given a directory entry, enter it into the fname rb tree. 333 */ 334 int ext4_htree_store_dirent(struct file *dir_file, __u32 hash, 335 __u32 minor_hash, 336 struct ext4_dir_entry_2 *dirent) 337 { 338 struct rb_node **p, *parent = NULL; 339 struct fname *fname, *new_fn; 340 struct dir_private_info *info; 341 int len; 342 343 info = (struct dir_private_info *) dir_file->private_data; 344 p = &info->root.rb_node; 345 346 /* Create and allocate the fname structure */ 347 len = sizeof(struct fname) + dirent->name_len + 1; 348 new_fn = kzalloc(len, GFP_KERNEL); 349 if (!new_fn) 350 return -ENOMEM; 351 new_fn->hash = hash; 352 new_fn->minor_hash = minor_hash; 353 new_fn->inode = le32_to_cpu(dirent->inode); 354 new_fn->name_len = dirent->name_len; 355 new_fn->file_type = dirent->file_type; 356 memcpy(new_fn->name, dirent->name, dirent->name_len); 357 new_fn->name[dirent->name_len] = 0; 358 359 while (*p) { 360 parent = *p; 361 fname = rb_entry(parent, struct fname, rb_hash); 362 363 /* 364 * If the hash and minor hash match up, then we put 365 * them on a linked list. This rarely happens... 366 */ 367 if ((new_fn->hash == fname->hash) && 368 (new_fn->minor_hash == fname->minor_hash)) { 369 new_fn->next = fname->next; 370 fname->next = new_fn; 371 return 0; 372 } 373 374 if (new_fn->hash < fname->hash) 375 p = &(*p)->rb_left; 376 else if (new_fn->hash > fname->hash) 377 p = &(*p)->rb_right; 378 else if (new_fn->minor_hash < fname->minor_hash) 379 p = &(*p)->rb_left; 380 else /* if (new_fn->minor_hash > fname->minor_hash) */ 381 p = &(*p)->rb_right; 382 } 383 384 rb_link_node(&new_fn->rb_hash, parent, p); 385 rb_insert_color(&new_fn->rb_hash, &info->root); 386 return 0; 387 } 388 389 390 391 /* 392 * This is a helper function for ext4_dx_readdir. It calls filldir 393 * for all entres on the fname linked list. (Normally there is only 394 * one entry on the linked list, unless there are 62 bit hash collisions.) 395 */ 396 static int call_filldir(struct file *filp, void *dirent, 397 filldir_t filldir, struct fname *fname) 398 { 399 struct dir_private_info *info = filp->private_data; 400 loff_t curr_pos; 401 struct inode *inode = filp->f_path.dentry->d_inode; 402 struct super_block *sb; 403 int error; 404 405 sb = inode->i_sb; 406 407 if (!fname) { 408 printk(KERN_ERR "EXT4-fs: call_filldir: called with " 409 "null fname?!?\n"); 410 return 0; 411 } 412 curr_pos = hash2pos(fname->hash, fname->minor_hash); 413 while (fname) { 414 error = filldir(dirent, fname->name, 415 fname->name_len, curr_pos, 416 fname->inode, 417 get_dtype(sb, fname->file_type)); 418 if (error) { 419 filp->f_pos = curr_pos; 420 info->extra_fname = fname; 421 return error; 422 } 423 fname = fname->next; 424 } 425 return 0; 426 } 427 428 static int ext4_dx_readdir(struct file *filp, 429 void *dirent, filldir_t filldir) 430 { 431 struct dir_private_info *info = filp->private_data; 432 struct inode *inode = filp->f_path.dentry->d_inode; 433 struct fname *fname; 434 int ret; 435 436 if (!info) { 437 info = ext4_htree_create_dir_info(filp->f_pos); 438 if (!info) 439 return -ENOMEM; 440 filp->private_data = info; 441 } 442 443 if (filp->f_pos == EXT4_HTREE_EOF) 444 return 0; /* EOF */ 445 446 /* Some one has messed with f_pos; reset the world */ 447 if (info->last_pos != filp->f_pos) { 448 free_rb_tree_fname(&info->root); 449 info->curr_node = NULL; 450 info->extra_fname = NULL; 451 info->curr_hash = pos2maj_hash(filp->f_pos); 452 info->curr_minor_hash = pos2min_hash(filp->f_pos); 453 } 454 455 /* 456 * If there are any leftover names on the hash collision 457 * chain, return them first. 458 */ 459 if (info->extra_fname) { 460 if (call_filldir(filp, dirent, filldir, info->extra_fname)) 461 goto finished; 462 info->extra_fname = NULL; 463 goto next_node; 464 } else if (!info->curr_node) 465 info->curr_node = rb_first(&info->root); 466 467 while (1) { 468 /* 469 * Fill the rbtree if we have no more entries, 470 * or the inode has changed since we last read in the 471 * cached entries. 472 */ 473 if ((!info->curr_node) || 474 (filp->f_version != inode->i_version)) { 475 info->curr_node = NULL; 476 free_rb_tree_fname(&info->root); 477 filp->f_version = inode->i_version; 478 ret = ext4_htree_fill_tree(filp, info->curr_hash, 479 info->curr_minor_hash, 480 &info->next_hash); 481 if (ret < 0) 482 return ret; 483 if (ret == 0) { 484 filp->f_pos = EXT4_HTREE_EOF; 485 break; 486 } 487 info->curr_node = rb_first(&info->root); 488 } 489 490 fname = rb_entry(info->curr_node, struct fname, rb_hash); 491 info->curr_hash = fname->hash; 492 info->curr_minor_hash = fname->minor_hash; 493 if (call_filldir(filp, dirent, filldir, fname)) 494 break; 495 next_node: 496 info->curr_node = rb_next(info->curr_node); 497 if (info->curr_node) { 498 fname = rb_entry(info->curr_node, struct fname, 499 rb_hash); 500 info->curr_hash = fname->hash; 501 info->curr_minor_hash = fname->minor_hash; 502 } else { 503 if (info->next_hash == ~0) { 504 filp->f_pos = EXT4_HTREE_EOF; 505 break; 506 } 507 info->curr_hash = info->next_hash; 508 info->curr_minor_hash = 0; 509 } 510 } 511 finished: 512 info->last_pos = filp->f_pos; 513 return 0; 514 } 515 516 static int ext4_release_dir(struct inode *inode, struct file *filp) 517 { 518 if (filp->private_data) 519 ext4_htree_free_dir_info(filp->private_data); 520 521 return 0; 522 } 523