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, 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 long 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=%lu, inode=%lu, rec_len=%d, name_len=%d", 88 dir->i_ino, error_msg, offset, 89 (unsigned long) 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 long 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; 105 106 sb = inode->i_sb; 107 108 if (EXT4_HAS_COMPAT_FEATURE(inode->i_sb, 109 EXT4_FEATURE_COMPAT_DIR_INDEX) && 110 ((EXT4_I(inode)->i_flags & EXT4_INDEX_FL) || 111 ((inode->i_size >> sb->s_blocksize_bits) == 1))) { 112 err = ext4_dx_readdir(filp, dirent, filldir); 113 if (err != ERR_BAD_DX_DIR) { 114 ret = err; 115 goto out; 116 } 117 /* 118 * We don't set the inode dirty flag since it's not 119 * critical that it get flushed back to the disk. 120 */ 121 EXT4_I(filp->f_path.dentry->d_inode)->i_flags &= ~EXT4_INDEX_FL; 122 } 123 stored = 0; 124 offset = filp->f_pos & (sb->s_blocksize - 1); 125 126 while (!error && !stored && filp->f_pos < inode->i_size) { 127 ext4_lblk_t blk = filp->f_pos >> EXT4_BLOCK_SIZE_BITS(sb); 128 struct buffer_head map_bh; 129 struct buffer_head *bh = NULL; 130 131 map_bh.b_state = 0; 132 err = ext4_get_blocks_wrap(NULL, inode, blk, 1, &map_bh, 0, 0); 133 if (err > 0) { 134 pgoff_t index = map_bh.b_blocknr >> 135 (PAGE_CACHE_SHIFT - inode->i_blkbits); 136 if (!ra_has_index(&filp->f_ra, index)) 137 page_cache_sync_readahead( 138 sb->s_bdev->bd_inode->i_mapping, 139 &filp->f_ra, filp, 140 index, 1); 141 filp->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT; 142 bh = ext4_bread(NULL, inode, blk, 0, &err); 143 } 144 145 /* 146 * We ignore I/O errors on directories so users have a chance 147 * of recovering data when there's a bad sector 148 */ 149 if (!bh) { 150 ext4_error (sb, "ext4_readdir", 151 "directory #%lu contains a hole at offset %lu", 152 inode->i_ino, (unsigned long)filp->f_pos); 153 /* corrupt size? Maybe no more blocks to read */ 154 if (filp->f_pos > inode->i_blocks << 9) 155 break; 156 filp->f_pos += sb->s_blocksize - offset; 157 continue; 158 } 159 160 revalidate: 161 /* If the dir block has changed since the last call to 162 * readdir(2), then we might be pointing to an invalid 163 * dirent right now. Scan from the start of the block 164 * to make sure. */ 165 if (filp->f_version != inode->i_version) { 166 for (i = 0; i < sb->s_blocksize && i < offset; ) { 167 de = (struct ext4_dir_entry_2 *) 168 (bh->b_data + i); 169 /* It's too expensive to do a full 170 * dirent test each time round this 171 * loop, but we do have to test at 172 * least that it is non-zero. A 173 * failure will be detected in the 174 * dirent test below. */ 175 if (ext4_rec_len_from_disk(de->rec_len) 176 < EXT4_DIR_REC_LEN(1)) 177 break; 178 i += ext4_rec_len_from_disk(de->rec_len); 179 } 180 offset = i; 181 filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1)) 182 | offset; 183 filp->f_version = inode->i_version; 184 } 185 186 while (!error && filp->f_pos < inode->i_size 187 && offset < sb->s_blocksize) { 188 de = (struct ext4_dir_entry_2 *) (bh->b_data + offset); 189 if (!ext4_check_dir_entry ("ext4_readdir", inode, de, 190 bh, offset)) { 191 /* 192 * On error, skip the f_pos to the next block 193 */ 194 filp->f_pos = (filp->f_pos | 195 (sb->s_blocksize - 1)) + 1; 196 brelse (bh); 197 ret = stored; 198 goto out; 199 } 200 offset += ext4_rec_len_from_disk(de->rec_len); 201 if (le32_to_cpu(de->inode)) { 202 /* We might block in the next section 203 * if the data destination is 204 * currently swapped out. So, use a 205 * version stamp to detect whether or 206 * not the directory has been modified 207 * during the copy operation. 208 */ 209 u64 version = filp->f_version; 210 211 error = filldir(dirent, de->name, 212 de->name_len, 213 filp->f_pos, 214 le32_to_cpu(de->inode), 215 get_dtype(sb, de->file_type)); 216 if (error) 217 break; 218 if (version != filp->f_version) 219 goto revalidate; 220 stored ++; 221 } 222 filp->f_pos += ext4_rec_len_from_disk(de->rec_len); 223 } 224 offset = 0; 225 brelse (bh); 226 } 227 out: 228 return ret; 229 } 230 231 /* 232 * These functions convert from the major/minor hash to an f_pos 233 * value. 234 * 235 * Currently we only use major hash numer. This is unfortunate, but 236 * on 32-bit machines, the same VFS interface is used for lseek and 237 * llseek, so if we use the 64 bit offset, then the 32-bit versions of 238 * lseek/telldir/seekdir will blow out spectacularly, and from within 239 * the ext2 low-level routine, we don't know if we're being called by 240 * a 64-bit version of the system call or the 32-bit version of the 241 * system call. Worse yet, NFSv2 only allows for a 32-bit readdir 242 * cookie. Sigh. 243 */ 244 #define hash2pos(major, minor) (major >> 1) 245 #define pos2maj_hash(pos) ((pos << 1) & 0xffffffff) 246 #define pos2min_hash(pos) (0) 247 248 /* 249 * This structure holds the nodes of the red-black tree used to store 250 * the directory entry in hash order. 251 */ 252 struct fname { 253 __u32 hash; 254 __u32 minor_hash; 255 struct rb_node rb_hash; 256 struct fname *next; 257 __u32 inode; 258 __u8 name_len; 259 __u8 file_type; 260 char name[0]; 261 }; 262 263 /* 264 * This functoin implements a non-recursive way of freeing all of the 265 * nodes in the red-black tree. 266 */ 267 static void free_rb_tree_fname(struct rb_root *root) 268 { 269 struct rb_node *n = root->rb_node; 270 struct rb_node *parent; 271 struct fname *fname; 272 273 while (n) { 274 /* Do the node's children first */ 275 if ((n)->rb_left) { 276 n = n->rb_left; 277 continue; 278 } 279 if (n->rb_right) { 280 n = n->rb_right; 281 continue; 282 } 283 /* 284 * The node has no children; free it, and then zero 285 * out parent's link to it. Finally go to the 286 * beginning of the loop and try to free the parent 287 * node. 288 */ 289 parent = rb_parent(n); 290 fname = rb_entry(n, struct fname, rb_hash); 291 while (fname) { 292 struct fname * old = fname; 293 fname = fname->next; 294 kfree (old); 295 } 296 if (!parent) 297 root->rb_node = NULL; 298 else if (parent->rb_left == n) 299 parent->rb_left = NULL; 300 else if (parent->rb_right == n) 301 parent->rb_right = NULL; 302 n = parent; 303 } 304 root->rb_node = NULL; 305 } 306 307 308 static struct dir_private_info *create_dir_info(loff_t pos) 309 { 310 struct dir_private_info *p; 311 312 p = kmalloc(sizeof(struct dir_private_info), GFP_KERNEL); 313 if (!p) 314 return NULL; 315 p->root.rb_node = NULL; 316 p->curr_node = NULL; 317 p->extra_fname = NULL; 318 p->last_pos = 0; 319 p->curr_hash = pos2maj_hash(pos); 320 p->curr_minor_hash = pos2min_hash(pos); 321 p->next_hash = 0; 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("call_filldir: called with null fname?!?\n"); 409 return 0; 410 } 411 curr_pos = hash2pos(fname->hash, fname->minor_hash); 412 while (fname) { 413 error = filldir(dirent, fname->name, 414 fname->name_len, curr_pos, 415 fname->inode, 416 get_dtype(sb, fname->file_type)); 417 if (error) { 418 filp->f_pos = curr_pos; 419 info->extra_fname = fname->next; 420 return error; 421 } 422 fname = fname->next; 423 } 424 return 0; 425 } 426 427 static int ext4_dx_readdir(struct file * filp, 428 void * dirent, filldir_t filldir) 429 { 430 struct dir_private_info *info = filp->private_data; 431 struct inode *inode = filp->f_path.dentry->d_inode; 432 struct fname *fname; 433 int ret; 434 435 if (!info) { 436 info = create_dir_info(filp->f_pos); 437 if (!info) 438 return -ENOMEM; 439 filp->private_data = info; 440 } 441 442 if (filp->f_pos == EXT4_HTREE_EOF) 443 return 0; /* EOF */ 444 445 /* Some one has messed with f_pos; reset the world */ 446 if (info->last_pos != filp->f_pos) { 447 free_rb_tree_fname(&info->root); 448 info->curr_node = NULL; 449 info->extra_fname = NULL; 450 info->curr_hash = pos2maj_hash(filp->f_pos); 451 info->curr_minor_hash = pos2min_hash(filp->f_pos); 452 } 453 454 /* 455 * If there are any leftover names on the hash collision 456 * chain, return them first. 457 */ 458 if (info->extra_fname && 459 call_filldir(filp, dirent, filldir, info->extra_fname)) 460 goto finished; 461 462 if (!info->curr_node) 463 info->curr_node = rb_first(&info->root); 464 465 while (1) { 466 /* 467 * Fill the rbtree if we have no more entries, 468 * or the inode has changed since we last read in the 469 * cached entries. 470 */ 471 if ((!info->curr_node) || 472 (filp->f_version != inode->i_version)) { 473 info->curr_node = NULL; 474 free_rb_tree_fname(&info->root); 475 filp->f_version = inode->i_version; 476 ret = ext4_htree_fill_tree(filp, info->curr_hash, 477 info->curr_minor_hash, 478 &info->next_hash); 479 if (ret < 0) 480 return ret; 481 if (ret == 0) { 482 filp->f_pos = EXT4_HTREE_EOF; 483 break; 484 } 485 info->curr_node = rb_first(&info->root); 486 } 487 488 fname = rb_entry(info->curr_node, struct fname, rb_hash); 489 info->curr_hash = fname->hash; 490 info->curr_minor_hash = fname->minor_hash; 491 if (call_filldir(filp, dirent, filldir, fname)) 492 break; 493 494 info->curr_node = rb_next(info->curr_node); 495 if (!info->curr_node) { 496 if (info->next_hash == ~0) { 497 filp->f_pos = EXT4_HTREE_EOF; 498 break; 499 } 500 info->curr_hash = info->next_hash; 501 info->curr_minor_hash = 0; 502 } 503 } 504 finished: 505 info->last_pos = filp->f_pos; 506 return 0; 507 } 508 509 static int ext4_release_dir (struct inode * inode, struct file * filp) 510 { 511 if (filp->private_data) 512 ext4_htree_free_dir_info(filp->private_data); 513 514 return 0; 515 } 516