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/ext4_fs.h> 27 #include <linux/buffer_head.h> 28 #include <linux/slab.h> 29 #include <linux/rbtree.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 .ioctl = ext4_ioctl, /* BKL held */ 46 #ifdef CONFIG_COMPAT 47 .compat_ioctl = ext4_compat_ioctl, 48 #endif 49 .fsync = ext4_sync_file, /* BKL held */ 50 #ifdef CONFIG_EXT4_INDEX 51 .release = ext4_release_dir, 52 #endif 53 }; 54 55 56 static unsigned char get_dtype(struct super_block *sb, int filetype) 57 { 58 if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FILETYPE) || 59 (filetype >= EXT4_FT_MAX)) 60 return DT_UNKNOWN; 61 62 return (ext4_filetype_table[filetype]); 63 } 64 65 66 int ext4_check_dir_entry (const char * function, struct inode * dir, 67 struct ext4_dir_entry_2 * de, 68 struct buffer_head * bh, 69 unsigned long offset) 70 { 71 const char * error_msg = NULL; 72 const int rlen = le16_to_cpu(de->rec_len); 73 74 if (rlen < EXT4_DIR_REC_LEN(1)) 75 error_msg = "rec_len is smaller than minimal"; 76 else if (rlen % 4 != 0) 77 error_msg = "rec_len % 4 != 0"; 78 else if (rlen < EXT4_DIR_REC_LEN(de->name_len)) 79 error_msg = "rec_len is too small for name_len"; 80 else if (((char *) de - bh->b_data) + rlen > dir->i_sb->s_blocksize) 81 error_msg = "directory entry across blocks"; 82 else if (le32_to_cpu(de->inode) > 83 le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count)) 84 error_msg = "inode out of bounds"; 85 86 if (error_msg != NULL) 87 ext4_error (dir->i_sb, function, 88 "bad entry in directory #%lu: %s - " 89 "offset=%lu, inode=%lu, rec_len=%d, name_len=%d", 90 dir->i_ino, error_msg, offset, 91 (unsigned long) le32_to_cpu(de->inode), 92 rlen, de->name_len); 93 return error_msg == NULL ? 1 : 0; 94 } 95 96 static int ext4_readdir(struct file * filp, 97 void * dirent, filldir_t filldir) 98 { 99 int error = 0; 100 unsigned long offset; 101 int i, stored; 102 struct ext4_dir_entry_2 *de; 103 struct super_block *sb; 104 int err; 105 struct inode *inode = filp->f_path.dentry->d_inode; 106 int ret = 0; 107 108 sb = inode->i_sb; 109 110 #ifdef CONFIG_EXT4_INDEX 111 if (EXT4_HAS_COMPAT_FEATURE(inode->i_sb, 112 EXT4_FEATURE_COMPAT_DIR_INDEX) && 113 ((EXT4_I(inode)->i_flags & EXT4_INDEX_FL) || 114 ((inode->i_size >> sb->s_blocksize_bits) == 1))) { 115 err = ext4_dx_readdir(filp, dirent, filldir); 116 if (err != ERR_BAD_DX_DIR) { 117 ret = err; 118 goto out; 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_I(filp->f_path.dentry->d_inode)->i_flags &= ~EXT4_INDEX_FL; 125 } 126 #endif 127 stored = 0; 128 offset = filp->f_pos & (sb->s_blocksize - 1); 129 130 while (!error && !stored && filp->f_pos < inode->i_size) { 131 unsigned long 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_wrap(NULL, inode, blk, 1, &map_bh, 0, 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_index = index; 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 ext4_error (sb, "ext4_readdir", 155 "directory #%lu contains a hole at offset %lu", 156 inode->i_ino, (unsigned long)filp->f_pos); 157 /* corrupt size? Maybe no more blocks to read */ 158 if (filp->f_pos > inode->i_blocks << 9) 159 break; 160 filp->f_pos += sb->s_blocksize - offset; 161 continue; 162 } 163 164 revalidate: 165 /* If the dir block has changed since the last call to 166 * readdir(2), then we might be pointing to an invalid 167 * dirent right now. Scan from the start of the block 168 * to make sure. */ 169 if (filp->f_version != inode->i_version) { 170 for (i = 0; i < sb->s_blocksize && i < offset; ) { 171 de = (struct ext4_dir_entry_2 *) 172 (bh->b_data + i); 173 /* It's too expensive to do a full 174 * dirent test each time round this 175 * loop, but we do have to test at 176 * least that it is non-zero. A 177 * failure will be detected in the 178 * dirent test below. */ 179 if (le16_to_cpu(de->rec_len) < 180 EXT4_DIR_REC_LEN(1)) 181 break; 182 i += le16_to_cpu(de->rec_len); 183 } 184 offset = i; 185 filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1)) 186 | offset; 187 filp->f_version = inode->i_version; 188 } 189 190 while (!error && filp->f_pos < inode->i_size 191 && offset < sb->s_blocksize) { 192 de = (struct ext4_dir_entry_2 *) (bh->b_data + offset); 193 if (!ext4_check_dir_entry ("ext4_readdir", inode, de, 194 bh, offset)) { 195 /* 196 * On error, skip the f_pos to the next block 197 */ 198 filp->f_pos = (filp->f_pos | 199 (sb->s_blocksize - 1)) + 1; 200 brelse (bh); 201 ret = stored; 202 goto out; 203 } 204 offset += le16_to_cpu(de->rec_len); 205 if (le32_to_cpu(de->inode)) { 206 /* We might block in the next section 207 * if the data destination is 208 * currently swapped out. So, use a 209 * version stamp to detect whether or 210 * not the directory has been modified 211 * during the copy operation. 212 */ 213 unsigned long version = filp->f_version; 214 215 error = filldir(dirent, de->name, 216 de->name_len, 217 filp->f_pos, 218 le32_to_cpu(de->inode), 219 get_dtype(sb, de->file_type)); 220 if (error) 221 break; 222 if (version != filp->f_version) 223 goto revalidate; 224 stored ++; 225 } 226 filp->f_pos += le16_to_cpu(de->rec_len); 227 } 228 offset = 0; 229 brelse (bh); 230 } 231 out: 232 return ret; 233 } 234 235 #ifdef CONFIG_EXT4_INDEX 236 /* 237 * These functions convert from the major/minor hash to an f_pos 238 * value. 239 * 240 * Currently we only use major hash numer. This is unfortunate, but 241 * on 32-bit machines, the same VFS interface is used for lseek and 242 * llseek, so if we use the 64 bit offset, then the 32-bit versions of 243 * lseek/telldir/seekdir will blow out spectacularly, and from within 244 * the ext2 low-level routine, we don't know if we're being called by 245 * a 64-bit version of the system call or the 32-bit version of the 246 * system call. Worse yet, NFSv2 only allows for a 32-bit readdir 247 * cookie. Sigh. 248 */ 249 #define hash2pos(major, minor) (major >> 1) 250 #define pos2maj_hash(pos) ((pos << 1) & 0xffffffff) 251 #define pos2min_hash(pos) (0) 252 253 /* 254 * This structure holds the nodes of the red-black tree used to store 255 * the directory entry in hash order. 256 */ 257 struct fname { 258 __u32 hash; 259 __u32 minor_hash; 260 struct rb_node rb_hash; 261 struct fname *next; 262 __u32 inode; 263 __u8 name_len; 264 __u8 file_type; 265 char name[0]; 266 }; 267 268 /* 269 * This functoin implements a non-recursive way of freeing all of the 270 * nodes in the red-black tree. 271 */ 272 static void free_rb_tree_fname(struct rb_root *root) 273 { 274 struct rb_node *n = root->rb_node; 275 struct rb_node *parent; 276 struct fname *fname; 277 278 while (n) { 279 /* Do the node's children first */ 280 if ((n)->rb_left) { 281 n = n->rb_left; 282 continue; 283 } 284 if (n->rb_right) { 285 n = n->rb_right; 286 continue; 287 } 288 /* 289 * The node has no children; free it, and then zero 290 * out parent's link to it. Finally go to the 291 * beginning of the loop and try to free the parent 292 * node. 293 */ 294 parent = rb_parent(n); 295 fname = rb_entry(n, struct fname, rb_hash); 296 while (fname) { 297 struct fname * old = fname; 298 fname = fname->next; 299 kfree (old); 300 } 301 if (!parent) 302 root->rb_node = NULL; 303 else if (parent->rb_left == n) 304 parent->rb_left = NULL; 305 else if (parent->rb_right == n) 306 parent->rb_right = NULL; 307 n = parent; 308 } 309 root->rb_node = NULL; 310 } 311 312 313 static struct dir_private_info *create_dir_info(loff_t pos) 314 { 315 struct dir_private_info *p; 316 317 p = kmalloc(sizeof(struct dir_private_info), GFP_KERNEL); 318 if (!p) 319 return NULL; 320 p->root.rb_node = NULL; 321 p->curr_node = NULL; 322 p->extra_fname = NULL; 323 p->last_pos = 0; 324 p->curr_hash = pos2maj_hash(pos); 325 p->curr_minor_hash = pos2min_hash(pos); 326 p->next_hash = 0; 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("call_filldir: called with null fname?!?\n"); 414 return 0; 415 } 416 curr_pos = hash2pos(fname->hash, fname->minor_hash); 417 while (fname) { 418 error = filldir(dirent, fname->name, 419 fname->name_len, curr_pos, 420 fname->inode, 421 get_dtype(sb, fname->file_type)); 422 if (error) { 423 filp->f_pos = curr_pos; 424 info->extra_fname = fname->next; 425 return error; 426 } 427 fname = fname->next; 428 } 429 return 0; 430 } 431 432 static int ext4_dx_readdir(struct file * filp, 433 void * dirent, filldir_t filldir) 434 { 435 struct dir_private_info *info = filp->private_data; 436 struct inode *inode = filp->f_path.dentry->d_inode; 437 struct fname *fname; 438 int ret; 439 440 if (!info) { 441 info = create_dir_info(filp->f_pos); 442 if (!info) 443 return -ENOMEM; 444 filp->private_data = info; 445 } 446 447 if (filp->f_pos == EXT4_HTREE_EOF) 448 return 0; /* EOF */ 449 450 /* Some one has messed with f_pos; reset the world */ 451 if (info->last_pos != filp->f_pos) { 452 free_rb_tree_fname(&info->root); 453 info->curr_node = NULL; 454 info->extra_fname = NULL; 455 info->curr_hash = pos2maj_hash(filp->f_pos); 456 info->curr_minor_hash = pos2min_hash(filp->f_pos); 457 } 458 459 /* 460 * If there are any leftover names on the hash collision 461 * chain, return them first. 462 */ 463 if (info->extra_fname && 464 call_filldir(filp, dirent, filldir, info->extra_fname)) 465 goto finished; 466 467 if (!info->curr_node) 468 info->curr_node = rb_first(&info->root); 469 470 while (1) { 471 /* 472 * Fill the rbtree if we have no more entries, 473 * or the inode has changed since we last read in the 474 * cached entries. 475 */ 476 if ((!info->curr_node) || 477 (filp->f_version != inode->i_version)) { 478 info->curr_node = NULL; 479 free_rb_tree_fname(&info->root); 480 filp->f_version = inode->i_version; 481 ret = ext4_htree_fill_tree(filp, info->curr_hash, 482 info->curr_minor_hash, 483 &info->next_hash); 484 if (ret < 0) 485 return ret; 486 if (ret == 0) { 487 filp->f_pos = EXT4_HTREE_EOF; 488 break; 489 } 490 info->curr_node = rb_first(&info->root); 491 } 492 493 fname = rb_entry(info->curr_node, struct fname, rb_hash); 494 info->curr_hash = fname->hash; 495 info->curr_minor_hash = fname->minor_hash; 496 if (call_filldir(filp, dirent, filldir, fname)) 497 break; 498 499 info->curr_node = rb_next(info->curr_node); 500 if (!info->curr_node) { 501 if (info->next_hash == ~0) { 502 filp->f_pos = EXT4_HTREE_EOF; 503 break; 504 } 505 info->curr_hash = info->next_hash; 506 info->curr_minor_hash = 0; 507 } 508 } 509 finished: 510 info->last_pos = filp->f_pos; 511 return 0; 512 } 513 514 static int ext4_release_dir (struct inode * inode, struct file * filp) 515 { 516 if (filp->private_data) 517 ext4_htree_free_dir_info(filp->private_data); 518 519 return 0; 520 } 521 522 #endif 523