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/smp_lock.h> 29 #include <linux/slab.h> 30 #include <linux/rbtree.h> 31 32 static unsigned char ext4_filetype_table[] = { 33 DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK, DT_FIFO, DT_SOCK, DT_LNK 34 }; 35 36 static int ext4_readdir(struct file *, void *, filldir_t); 37 static int ext4_dx_readdir(struct file * filp, 38 void * dirent, filldir_t filldir); 39 static int ext4_release_dir (struct inode * inode, 40 struct file * filp); 41 42 const struct file_operations ext4_dir_operations = { 43 .llseek = generic_file_llseek, 44 .read = generic_read_dir, 45 .readdir = ext4_readdir, /* we take BKL. needed?*/ 46 .ioctl = ext4_ioctl, /* BKL held */ 47 #ifdef CONFIG_COMPAT 48 .compat_ioctl = ext4_compat_ioctl, 49 #endif 50 .fsync = ext4_sync_file, /* BKL held */ 51 #ifdef CONFIG_EXT4_INDEX 52 .release = ext4_release_dir, 53 #endif 54 }; 55 56 57 static unsigned char get_dtype(struct super_block *sb, int filetype) 58 { 59 if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FILETYPE) || 60 (filetype >= EXT4_FT_MAX)) 61 return DT_UNKNOWN; 62 63 return (ext4_filetype_table[filetype]); 64 } 65 66 67 int ext4_check_dir_entry (const char * function, struct inode * dir, 68 struct ext4_dir_entry_2 * de, 69 struct buffer_head * bh, 70 unsigned long offset) 71 { 72 const char * error_msg = NULL; 73 const int rlen = le16_to_cpu(de->rec_len); 74 75 if (rlen < EXT4_DIR_REC_LEN(1)) 76 error_msg = "rec_len is smaller than minimal"; 77 else if (rlen % 4 != 0) 78 error_msg = "rec_len % 4 != 0"; 79 else if (rlen < EXT4_DIR_REC_LEN(de->name_len)) 80 error_msg = "rec_len is too small for name_len"; 81 else if (((char *) de - bh->b_data) + rlen > dir->i_sb->s_blocksize) 82 error_msg = "directory entry across blocks"; 83 else if (le32_to_cpu(de->inode) > 84 le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count)) 85 error_msg = "inode out of bounds"; 86 87 if (error_msg != NULL) 88 ext4_error (dir->i_sb, function, 89 "bad entry in directory #%lu: %s - " 90 "offset=%lu, inode=%lu, rec_len=%d, name_len=%d", 91 dir->i_ino, error_msg, offset, 92 (unsigned long) 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 long 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; 108 109 sb = inode->i_sb; 110 111 #ifdef CONFIG_EXT4_INDEX 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 #endif 128 stored = 0; 129 offset = filp->f_pos & (sb->s_blocksize - 1); 130 131 while (!error && !stored && filp->f_pos < inode->i_size) { 132 unsigned long blk = filp->f_pos >> EXT4_BLOCK_SIZE_BITS(sb); 133 struct buffer_head map_bh; 134 struct buffer_head *bh = NULL; 135 136 map_bh.b_state = 0; 137 err = ext4_get_blocks_wrap(NULL, inode, blk, 1, &map_bh, 0, 0); 138 if (err > 0) { 139 page_cache_readahead(sb->s_bdev->bd_inode->i_mapping, 140 &filp->f_ra, 141 filp, 142 map_bh.b_blocknr >> 143 (PAGE_CACHE_SHIFT - inode->i_blkbits), 144 1); 145 bh = ext4_bread(NULL, inode, blk, 0, &err); 146 } 147 148 /* 149 * We ignore I/O errors on directories so users have a chance 150 * of recovering data when there's a bad sector 151 */ 152 if (!bh) { 153 ext4_error (sb, "ext4_readdir", 154 "directory #%lu contains a hole at offset %lu", 155 inode->i_ino, (unsigned long)filp->f_pos); 156 /* corrupt size? Maybe no more blocks to read */ 157 if (filp->f_pos > inode->i_blocks << 9) 158 break; 159 filp->f_pos += sb->s_blocksize - offset; 160 continue; 161 } 162 163 revalidate: 164 /* If the dir block has changed since the last call to 165 * readdir(2), then we might be pointing to an invalid 166 * dirent right now. Scan from the start of the block 167 * to make sure. */ 168 if (filp->f_version != inode->i_version) { 169 for (i = 0; i < sb->s_blocksize && i < offset; ) { 170 de = (struct ext4_dir_entry_2 *) 171 (bh->b_data + i); 172 /* It's too expensive to do a full 173 * dirent test each time round this 174 * loop, but we do have to test at 175 * least that it is non-zero. A 176 * failure will be detected in the 177 * dirent test below. */ 178 if (le16_to_cpu(de->rec_len) < 179 EXT4_DIR_REC_LEN(1)) 180 break; 181 i += le16_to_cpu(de->rec_len); 182 } 183 offset = i; 184 filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1)) 185 | offset; 186 filp->f_version = inode->i_version; 187 } 188 189 while (!error && filp->f_pos < inode->i_size 190 && offset < sb->s_blocksize) { 191 de = (struct ext4_dir_entry_2 *) (bh->b_data + offset); 192 if (!ext4_check_dir_entry ("ext4_readdir", inode, de, 193 bh, offset)) { 194 /* 195 * On error, skip the f_pos to the next block 196 */ 197 filp->f_pos = (filp->f_pos | 198 (sb->s_blocksize - 1)) + 1; 199 brelse (bh); 200 ret = stored; 201 goto out; 202 } 203 offset += le16_to_cpu(de->rec_len); 204 if (le32_to_cpu(de->inode)) { 205 /* We might block in the next section 206 * if the data destination is 207 * currently swapped out. So, use a 208 * version stamp to detect whether or 209 * not the directory has been modified 210 * during the copy operation. 211 */ 212 unsigned long version = filp->f_version; 213 214 error = filldir(dirent, de->name, 215 de->name_len, 216 filp->f_pos, 217 le32_to_cpu(de->inode), 218 get_dtype(sb, de->file_type)); 219 if (error) 220 break; 221 if (version != filp->f_version) 222 goto revalidate; 223 stored ++; 224 } 225 filp->f_pos += le16_to_cpu(de->rec_len); 226 } 227 offset = 0; 228 brelse (bh); 229 } 230 out: 231 return ret; 232 } 233 234 #ifdef CONFIG_EXT4_INDEX 235 /* 236 * These functions convert from the major/minor hash to an f_pos 237 * value. 238 * 239 * Currently we only use major hash numer. This is unfortunate, but 240 * on 32-bit machines, the same VFS interface is used for lseek and 241 * llseek, so if we use the 64 bit offset, then the 32-bit versions of 242 * lseek/telldir/seekdir will blow out spectacularly, and from within 243 * the ext2 low-level routine, we don't know if we're being called by 244 * a 64-bit version of the system call or the 32-bit version of the 245 * system call. Worse yet, NFSv2 only allows for a 32-bit readdir 246 * cookie. Sigh. 247 */ 248 #define hash2pos(major, minor) (major >> 1) 249 #define pos2maj_hash(pos) ((pos << 1) & 0xffffffff) 250 #define pos2min_hash(pos) (0) 251 252 /* 253 * This structure holds the nodes of the red-black tree used to store 254 * the directory entry in hash order. 255 */ 256 struct fname { 257 __u32 hash; 258 __u32 minor_hash; 259 struct rb_node rb_hash; 260 struct fname *next; 261 __u32 inode; 262 __u8 name_len; 263 __u8 file_type; 264 char name[0]; 265 }; 266 267 /* 268 * This functoin implements a non-recursive way of freeing all of the 269 * nodes in the red-black tree. 270 */ 271 static void free_rb_tree_fname(struct rb_root *root) 272 { 273 struct rb_node *n = root->rb_node; 274 struct rb_node *parent; 275 struct fname *fname; 276 277 while (n) { 278 /* Do the node's children first */ 279 if ((n)->rb_left) { 280 n = n->rb_left; 281 continue; 282 } 283 if (n->rb_right) { 284 n = n->rb_right; 285 continue; 286 } 287 /* 288 * The node has no children; free it, and then zero 289 * out parent's link to it. Finally go to the 290 * beginning of the loop and try to free the parent 291 * node. 292 */ 293 parent = rb_parent(n); 294 fname = rb_entry(n, struct fname, rb_hash); 295 while (fname) { 296 struct fname * old = fname; 297 fname = fname->next; 298 kfree (old); 299 } 300 if (!parent) 301 root->rb_node = NULL; 302 else if (parent->rb_left == n) 303 parent->rb_left = NULL; 304 else if (parent->rb_right == n) 305 parent->rb_right = NULL; 306 n = parent; 307 } 308 root->rb_node = NULL; 309 } 310 311 312 static struct dir_private_info *create_dir_info(loff_t pos) 313 { 314 struct dir_private_info *p; 315 316 p = kmalloc(sizeof(struct dir_private_info), GFP_KERNEL); 317 if (!p) 318 return NULL; 319 p->root.rb_node = NULL; 320 p->curr_node = NULL; 321 p->extra_fname = NULL; 322 p->last_pos = 0; 323 p->curr_hash = pos2maj_hash(pos); 324 p->curr_minor_hash = pos2min_hash(pos); 325 p->next_hash = 0; 326 return p; 327 } 328 329 void ext4_htree_free_dir_info(struct dir_private_info *p) 330 { 331 free_rb_tree_fname(&p->root); 332 kfree(p); 333 } 334 335 /* 336 * Given a directory entry, enter it into the fname rb tree. 337 */ 338 int ext4_htree_store_dirent(struct file *dir_file, __u32 hash, 339 __u32 minor_hash, 340 struct ext4_dir_entry_2 *dirent) 341 { 342 struct rb_node **p, *parent = NULL; 343 struct fname * fname, *new_fn; 344 struct dir_private_info *info; 345 int len; 346 347 info = (struct dir_private_info *) dir_file->private_data; 348 p = &info->root.rb_node; 349 350 /* Create and allocate the fname structure */ 351 len = sizeof(struct fname) + dirent->name_len + 1; 352 new_fn = kzalloc(len, GFP_KERNEL); 353 if (!new_fn) 354 return -ENOMEM; 355 new_fn->hash = hash; 356 new_fn->minor_hash = minor_hash; 357 new_fn->inode = le32_to_cpu(dirent->inode); 358 new_fn->name_len = dirent->name_len; 359 new_fn->file_type = dirent->file_type; 360 memcpy(new_fn->name, dirent->name, dirent->name_len); 361 new_fn->name[dirent->name_len] = 0; 362 363 while (*p) { 364 parent = *p; 365 fname = rb_entry(parent, struct fname, rb_hash); 366 367 /* 368 * If the hash and minor hash match up, then we put 369 * them on a linked list. This rarely happens... 370 */ 371 if ((new_fn->hash == fname->hash) && 372 (new_fn->minor_hash == fname->minor_hash)) { 373 new_fn->next = fname->next; 374 fname->next = new_fn; 375 return 0; 376 } 377 378 if (new_fn->hash < fname->hash) 379 p = &(*p)->rb_left; 380 else if (new_fn->hash > fname->hash) 381 p = &(*p)->rb_right; 382 else if (new_fn->minor_hash < fname->minor_hash) 383 p = &(*p)->rb_left; 384 else /* if (new_fn->minor_hash > fname->minor_hash) */ 385 p = &(*p)->rb_right; 386 } 387 388 rb_link_node(&new_fn->rb_hash, parent, p); 389 rb_insert_color(&new_fn->rb_hash, &info->root); 390 return 0; 391 } 392 393 394 395 /* 396 * This is a helper function for ext4_dx_readdir. It calls filldir 397 * for all entres on the fname linked list. (Normally there is only 398 * one entry on the linked list, unless there are 62 bit hash collisions.) 399 */ 400 static int call_filldir(struct file * filp, void * dirent, 401 filldir_t filldir, struct fname *fname) 402 { 403 struct dir_private_info *info = filp->private_data; 404 loff_t curr_pos; 405 struct inode *inode = filp->f_path.dentry->d_inode; 406 struct super_block * sb; 407 int error; 408 409 sb = inode->i_sb; 410 411 if (!fname) { 412 printk("call_filldir: called with null fname?!?\n"); 413 return 0; 414 } 415 curr_pos = hash2pos(fname->hash, fname->minor_hash); 416 while (fname) { 417 error = filldir(dirent, fname->name, 418 fname->name_len, curr_pos, 419 fname->inode, 420 get_dtype(sb, fname->file_type)); 421 if (error) { 422 filp->f_pos = curr_pos; 423 info->extra_fname = fname->next; 424 return error; 425 } 426 fname = fname->next; 427 } 428 return 0; 429 } 430 431 static int ext4_dx_readdir(struct file * filp, 432 void * dirent, filldir_t filldir) 433 { 434 struct dir_private_info *info = filp->private_data; 435 struct inode *inode = filp->f_path.dentry->d_inode; 436 struct fname *fname; 437 int ret; 438 439 if (!info) { 440 info = create_dir_info(filp->f_pos); 441 if (!info) 442 return -ENOMEM; 443 filp->private_data = info; 444 } 445 446 if (filp->f_pos == EXT4_HTREE_EOF) 447 return 0; /* EOF */ 448 449 /* Some one has messed with f_pos; reset the world */ 450 if (info->last_pos != filp->f_pos) { 451 free_rb_tree_fname(&info->root); 452 info->curr_node = NULL; 453 info->extra_fname = NULL; 454 info->curr_hash = pos2maj_hash(filp->f_pos); 455 info->curr_minor_hash = pos2min_hash(filp->f_pos); 456 } 457 458 /* 459 * If there are any leftover names on the hash collision 460 * chain, return them first. 461 */ 462 if (info->extra_fname && 463 call_filldir(filp, dirent, filldir, info->extra_fname)) 464 goto finished; 465 466 if (!info->curr_node) 467 info->curr_node = rb_first(&info->root); 468 469 while (1) { 470 /* 471 * Fill the rbtree if we have no more entries, 472 * or the inode has changed since we last read in the 473 * cached entries. 474 */ 475 if ((!info->curr_node) || 476 (filp->f_version != inode->i_version)) { 477 info->curr_node = NULL; 478 free_rb_tree_fname(&info->root); 479 filp->f_version = inode->i_version; 480 ret = ext4_htree_fill_tree(filp, info->curr_hash, 481 info->curr_minor_hash, 482 &info->next_hash); 483 if (ret < 0) 484 return ret; 485 if (ret == 0) { 486 filp->f_pos = EXT4_HTREE_EOF; 487 break; 488 } 489 info->curr_node = rb_first(&info->root); 490 } 491 492 fname = rb_entry(info->curr_node, struct fname, rb_hash); 493 info->curr_hash = fname->hash; 494 info->curr_minor_hash = fname->minor_hash; 495 if (call_filldir(filp, dirent, filldir, fname)) 496 break; 497 498 info->curr_node = rb_next(info->curr_node); 499 if (!info->curr_node) { 500 if (info->next_hash == ~0) { 501 filp->f_pos = EXT4_HTREE_EOF; 502 break; 503 } 504 info->curr_hash = info->next_hash; 505 info->curr_minor_hash = 0; 506 } 507 } 508 finished: 509 info->last_pos = filp->f_pos; 510 return 0; 511 } 512 513 static int ext4_release_dir (struct inode * inode, struct file * filp) 514 { 515 if (filp->private_data) 516 ext4_htree_free_dir_info(filp->private_data); 517 518 return 0; 519 } 520 521 #endif 522