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 page_cache_readahead(sb->s_bdev->bd_inode->i_mapping, 139 &filp->f_ra, 140 filp, 141 map_bh.b_blocknr >> 142 (PAGE_CACHE_SHIFT - inode->i_blkbits), 143 1); 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 ext4_error (sb, "ext4_readdir", 153 "directory #%lu contains a hole at offset %lu", 154 inode->i_ino, (unsigned long)filp->f_pos); 155 /* corrupt size? Maybe no more blocks to read */ 156 if (filp->f_pos > inode->i_blocks << 9) 157 break; 158 filp->f_pos += sb->s_blocksize - offset; 159 continue; 160 } 161 162 revalidate: 163 /* If the dir block has changed since the last call to 164 * readdir(2), then we might be pointing to an invalid 165 * dirent right now. Scan from the start of the block 166 * to make sure. */ 167 if (filp->f_version != inode->i_version) { 168 for (i = 0; i < sb->s_blocksize && i < offset; ) { 169 de = (struct ext4_dir_entry_2 *) 170 (bh->b_data + i); 171 /* It's too expensive to do a full 172 * dirent test each time round this 173 * loop, but we do have to test at 174 * least that it is non-zero. A 175 * failure will be detected in the 176 * dirent test below. */ 177 if (le16_to_cpu(de->rec_len) < 178 EXT4_DIR_REC_LEN(1)) 179 break; 180 i += le16_to_cpu(de->rec_len); 181 } 182 offset = i; 183 filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1)) 184 | offset; 185 filp->f_version = inode->i_version; 186 } 187 188 while (!error && filp->f_pos < inode->i_size 189 && offset < sb->s_blocksize) { 190 de = (struct ext4_dir_entry_2 *) (bh->b_data + offset); 191 if (!ext4_check_dir_entry ("ext4_readdir", inode, de, 192 bh, offset)) { 193 /* 194 * On error, skip the f_pos to the next block 195 */ 196 filp->f_pos = (filp->f_pos | 197 (sb->s_blocksize - 1)) + 1; 198 brelse (bh); 199 ret = stored; 200 goto out; 201 } 202 offset += le16_to_cpu(de->rec_len); 203 if (le32_to_cpu(de->inode)) { 204 /* We might block in the next section 205 * if the data destination is 206 * currently swapped out. So, use a 207 * version stamp to detect whether or 208 * not the directory has been modified 209 * during the copy operation. 210 */ 211 unsigned long version = filp->f_version; 212 213 error = filldir(dirent, de->name, 214 de->name_len, 215 filp->f_pos, 216 le32_to_cpu(de->inode), 217 get_dtype(sb, de->file_type)); 218 if (error) 219 break; 220 if (version != filp->f_version) 221 goto revalidate; 222 stored ++; 223 } 224 filp->f_pos += le16_to_cpu(de->rec_len); 225 } 226 offset = 0; 227 brelse (bh); 228 } 229 out: 230 return ret; 231 } 232 233 #ifdef CONFIG_EXT4_INDEX 234 /* 235 * These functions convert from the major/minor hash to an f_pos 236 * value. 237 * 238 * Currently we only use major hash numer. This is unfortunate, but 239 * on 32-bit machines, the same VFS interface is used for lseek and 240 * llseek, so if we use the 64 bit offset, then the 32-bit versions of 241 * lseek/telldir/seekdir will blow out spectacularly, and from within 242 * the ext2 low-level routine, we don't know if we're being called by 243 * a 64-bit version of the system call or the 32-bit version of the 244 * system call. Worse yet, NFSv2 only allows for a 32-bit readdir 245 * cookie. Sigh. 246 */ 247 #define hash2pos(major, minor) (major >> 1) 248 #define pos2maj_hash(pos) ((pos << 1) & 0xffffffff) 249 #define pos2min_hash(pos) (0) 250 251 /* 252 * This structure holds the nodes of the red-black tree used to store 253 * the directory entry in hash order. 254 */ 255 struct fname { 256 __u32 hash; 257 __u32 minor_hash; 258 struct rb_node rb_hash; 259 struct fname *next; 260 __u32 inode; 261 __u8 name_len; 262 __u8 file_type; 263 char name[0]; 264 }; 265 266 /* 267 * This functoin implements a non-recursive way of freeing all of the 268 * nodes in the red-black tree. 269 */ 270 static void free_rb_tree_fname(struct rb_root *root) 271 { 272 struct rb_node *n = root->rb_node; 273 struct rb_node *parent; 274 struct fname *fname; 275 276 while (n) { 277 /* Do the node's children first */ 278 if ((n)->rb_left) { 279 n = n->rb_left; 280 continue; 281 } 282 if (n->rb_right) { 283 n = n->rb_right; 284 continue; 285 } 286 /* 287 * The node has no children; free it, and then zero 288 * out parent's link to it. Finally go to the 289 * beginning of the loop and try to free the parent 290 * node. 291 */ 292 parent = rb_parent(n); 293 fname = rb_entry(n, struct fname, rb_hash); 294 while (fname) { 295 struct fname * old = fname; 296 fname = fname->next; 297 kfree (old); 298 } 299 if (!parent) 300 root->rb_node = NULL; 301 else if (parent->rb_left == n) 302 parent->rb_left = NULL; 303 else if (parent->rb_right == n) 304 parent->rb_right = NULL; 305 n = parent; 306 } 307 root->rb_node = NULL; 308 } 309 310 311 static struct dir_private_info *create_dir_info(loff_t pos) 312 { 313 struct dir_private_info *p; 314 315 p = kmalloc(sizeof(struct dir_private_info), GFP_KERNEL); 316 if (!p) 317 return NULL; 318 p->root.rb_node = NULL; 319 p->curr_node = NULL; 320 p->extra_fname = NULL; 321 p->last_pos = 0; 322 p->curr_hash = pos2maj_hash(pos); 323 p->curr_minor_hash = pos2min_hash(pos); 324 p->next_hash = 0; 325 return p; 326 } 327 328 void ext4_htree_free_dir_info(struct dir_private_info *p) 329 { 330 free_rb_tree_fname(&p->root); 331 kfree(p); 332 } 333 334 /* 335 * Given a directory entry, enter it into the fname rb tree. 336 */ 337 int ext4_htree_store_dirent(struct file *dir_file, __u32 hash, 338 __u32 minor_hash, 339 struct ext4_dir_entry_2 *dirent) 340 { 341 struct rb_node **p, *parent = NULL; 342 struct fname * fname, *new_fn; 343 struct dir_private_info *info; 344 int len; 345 346 info = (struct dir_private_info *) dir_file->private_data; 347 p = &info->root.rb_node; 348 349 /* Create and allocate the fname structure */ 350 len = sizeof(struct fname) + dirent->name_len + 1; 351 new_fn = kzalloc(len, GFP_KERNEL); 352 if (!new_fn) 353 return -ENOMEM; 354 new_fn->hash = hash; 355 new_fn->minor_hash = minor_hash; 356 new_fn->inode = le32_to_cpu(dirent->inode); 357 new_fn->name_len = dirent->name_len; 358 new_fn->file_type = dirent->file_type; 359 memcpy(new_fn->name, dirent->name, dirent->name_len); 360 new_fn->name[dirent->name_len] = 0; 361 362 while (*p) { 363 parent = *p; 364 fname = rb_entry(parent, struct fname, rb_hash); 365 366 /* 367 * If the hash and minor hash match up, then we put 368 * them on a linked list. This rarely happens... 369 */ 370 if ((new_fn->hash == fname->hash) && 371 (new_fn->minor_hash == fname->minor_hash)) { 372 new_fn->next = fname->next; 373 fname->next = new_fn; 374 return 0; 375 } 376 377 if (new_fn->hash < fname->hash) 378 p = &(*p)->rb_left; 379 else if (new_fn->hash > fname->hash) 380 p = &(*p)->rb_right; 381 else if (new_fn->minor_hash < fname->minor_hash) 382 p = &(*p)->rb_left; 383 else /* if (new_fn->minor_hash > fname->minor_hash) */ 384 p = &(*p)->rb_right; 385 } 386 387 rb_link_node(&new_fn->rb_hash, parent, p); 388 rb_insert_color(&new_fn->rb_hash, &info->root); 389 return 0; 390 } 391 392 393 394 /* 395 * This is a helper function for ext4_dx_readdir. It calls filldir 396 * for all entres on the fname linked list. (Normally there is only 397 * one entry on the linked list, unless there are 62 bit hash collisions.) 398 */ 399 static int call_filldir(struct file * filp, void * dirent, 400 filldir_t filldir, struct fname *fname) 401 { 402 struct dir_private_info *info = filp->private_data; 403 loff_t curr_pos; 404 struct inode *inode = filp->f_path.dentry->d_inode; 405 struct super_block * sb; 406 int error; 407 408 sb = inode->i_sb; 409 410 if (!fname) { 411 printk("call_filldir: called with null fname?!?\n"); 412 return 0; 413 } 414 curr_pos = hash2pos(fname->hash, fname->minor_hash); 415 while (fname) { 416 error = filldir(dirent, fname->name, 417 fname->name_len, curr_pos, 418 fname->inode, 419 get_dtype(sb, fname->file_type)); 420 if (error) { 421 filp->f_pos = curr_pos; 422 info->extra_fname = fname->next; 423 return error; 424 } 425 fname = fname->next; 426 } 427 return 0; 428 } 429 430 static int ext4_dx_readdir(struct file * filp, 431 void * dirent, filldir_t filldir) 432 { 433 struct dir_private_info *info = filp->private_data; 434 struct inode *inode = filp->f_path.dentry->d_inode; 435 struct fname *fname; 436 int ret; 437 438 if (!info) { 439 info = create_dir_info(filp->f_pos); 440 if (!info) 441 return -ENOMEM; 442 filp->private_data = info; 443 } 444 445 if (filp->f_pos == EXT4_HTREE_EOF) 446 return 0; /* EOF */ 447 448 /* Some one has messed with f_pos; reset the world */ 449 if (info->last_pos != filp->f_pos) { 450 free_rb_tree_fname(&info->root); 451 info->curr_node = NULL; 452 info->extra_fname = NULL; 453 info->curr_hash = pos2maj_hash(filp->f_pos); 454 info->curr_minor_hash = pos2min_hash(filp->f_pos); 455 } 456 457 /* 458 * If there are any leftover names on the hash collision 459 * chain, return them first. 460 */ 461 if (info->extra_fname && 462 call_filldir(filp, dirent, filldir, info->extra_fname)) 463 goto finished; 464 465 if (!info->curr_node) 466 info->curr_node = rb_first(&info->root); 467 468 while (1) { 469 /* 470 * Fill the rbtree if we have no more entries, 471 * or the inode has changed since we last read in the 472 * cached entries. 473 */ 474 if ((!info->curr_node) || 475 (filp->f_version != inode->i_version)) { 476 info->curr_node = NULL; 477 free_rb_tree_fname(&info->root); 478 filp->f_version = inode->i_version; 479 ret = ext4_htree_fill_tree(filp, info->curr_hash, 480 info->curr_minor_hash, 481 &info->next_hash); 482 if (ret < 0) 483 return ret; 484 if (ret == 0) { 485 filp->f_pos = EXT4_HTREE_EOF; 486 break; 487 } 488 info->curr_node = rb_first(&info->root); 489 } 490 491 fname = rb_entry(info->curr_node, struct fname, rb_hash); 492 info->curr_hash = fname->hash; 493 info->curr_minor_hash = fname->minor_hash; 494 if (call_filldir(filp, dirent, filldir, fname)) 495 break; 496 497 info->curr_node = rb_next(info->curr_node); 498 if (!info->curr_node) { 499 if (info->next_hash == ~0) { 500 filp->f_pos = EXT4_HTREE_EOF; 501 break; 502 } 503 info->curr_hash = info->next_hash; 504 info->curr_minor_hash = 0; 505 } 506 } 507 finished: 508 info->last_pos = filp->f_pos; 509 return 0; 510 } 511 512 static int ext4_release_dir (struct inode * inode, struct file * filp) 513 { 514 if (filp->private_data) 515 ext4_htree_free_dir_info(filp->private_data); 516 517 return 0; 518 } 519 520 #endif 521