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 dir->i_sb->s_blocksize); 72 73 if (rlen < EXT4_DIR_REC_LEN(1)) 74 error_msg = "rec_len is smaller than minimal"; 75 else if (rlen % 4 != 0) 76 error_msg = "rec_len % 4 != 0"; 77 else if (rlen < EXT4_DIR_REC_LEN(de->name_len)) 78 error_msg = "rec_len is too small for name_len"; 79 else if (((char *) de - bh->b_data) + rlen > dir->i_sb->s_blocksize) 80 error_msg = "directory entry across blocks"; 81 else if (le32_to_cpu(de->inode) > 82 le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count)) 83 error_msg = "inode out of bounds"; 84 85 if (error_msg != NULL) 86 ext4_error_inode(function, dir, 87 "bad entry in directory: %s - block=%llu" 88 "offset=%u(%u), inode=%u, rec_len=%d, name_len=%d", 89 error_msg, (unsigned long long) bh->b_blocknr, 90 (unsigned) (offset%bh->b_size), offset, 91 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 int 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 int dir_has_error = 0; 108 109 sb = inode->i_sb; 110 111 if (EXT4_HAS_COMPAT_FEATURE(inode->i_sb, 112 EXT4_FEATURE_COMPAT_DIR_INDEX) && 113 ((ext4_test_inode_flag(inode, EXT4_INODE_INDEX)) || 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_clear_inode_flag(filp->f_path.dentry->d_inode, EXT4_INODE_INDEX); 125 } 126 stored = 0; 127 offset = filp->f_pos & (sb->s_blocksize - 1); 128 129 while (!error && !stored && filp->f_pos < inode->i_size) { 130 struct ext4_map_blocks map; 131 struct buffer_head *bh = NULL; 132 133 map.m_lblk = filp->f_pos >> EXT4_BLOCK_SIZE_BITS(sb); 134 map.m_len = 1; 135 err = ext4_map_blocks(NULL, inode, &map, 0); 136 if (err > 0) { 137 pgoff_t index = map.m_pblk >> 138 (PAGE_CACHE_SHIFT - inode->i_blkbits); 139 if (!ra_has_index(&filp->f_ra, index)) 140 page_cache_sync_readahead( 141 sb->s_bdev->bd_inode->i_mapping, 142 &filp->f_ra, filp, 143 index, 1); 144 filp->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT; 145 bh = ext4_bread(NULL, inode, map.m_lblk, 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 if (!dir_has_error) { 154 EXT4_ERROR_INODE(inode, "directory " 155 "contains a hole at offset %Lu", 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 sb->s_blocksize) < EXT4_DIR_REC_LEN(1)) 183 break; 184 i += ext4_rec_len_from_disk(de->rec_len, 185 sb->s_blocksize); 186 } 187 offset = i; 188 filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1)) 189 | offset; 190 filp->f_version = inode->i_version; 191 } 192 193 while (!error && filp->f_pos < inode->i_size 194 && offset < sb->s_blocksize) { 195 de = (struct ext4_dir_entry_2 *) (bh->b_data + offset); 196 if (!ext4_check_dir_entry("ext4_readdir", inode, de, 197 bh, offset)) { 198 /* 199 * On error, skip the f_pos to the next block 200 */ 201 filp->f_pos = (filp->f_pos | 202 (sb->s_blocksize - 1)) + 1; 203 brelse(bh); 204 ret = stored; 205 goto out; 206 } 207 offset += ext4_rec_len_from_disk(de->rec_len, 208 sb->s_blocksize); 209 if (le32_to_cpu(de->inode)) { 210 /* We might block in the next section 211 * if the data destination is 212 * currently swapped out. So, use a 213 * version stamp to detect whether or 214 * not the directory has been modified 215 * during the copy operation. 216 */ 217 u64 version = filp->f_version; 218 219 error = filldir(dirent, de->name, 220 de->name_len, 221 filp->f_pos, 222 le32_to_cpu(de->inode), 223 get_dtype(sb, de->file_type)); 224 if (error) 225 break; 226 if (version != filp->f_version) 227 goto revalidate; 228 stored++; 229 } 230 filp->f_pos += ext4_rec_len_from_disk(de->rec_len, 231 sb->s_blocksize); 232 } 233 offset = 0; 234 brelse(bh); 235 } 236 out: 237 return ret; 238 } 239 240 /* 241 * These functions convert from the major/minor hash to an f_pos 242 * value. 243 * 244 * Currently we only use major hash numer. This is unfortunate, but 245 * on 32-bit machines, the same VFS interface is used for lseek and 246 * llseek, so if we use the 64 bit offset, then the 32-bit versions of 247 * lseek/telldir/seekdir will blow out spectacularly, and from within 248 * the ext2 low-level routine, we don't know if we're being called by 249 * a 64-bit version of the system call or the 32-bit version of the 250 * system call. Worse yet, NFSv2 only allows for a 32-bit readdir 251 * cookie. Sigh. 252 */ 253 #define hash2pos(major, minor) (major >> 1) 254 #define pos2maj_hash(pos) ((pos << 1) & 0xffffffff) 255 #define pos2min_hash(pos) (0) 256 257 /* 258 * This structure holds the nodes of the red-black tree used to store 259 * the directory entry in hash order. 260 */ 261 struct fname { 262 __u32 hash; 263 __u32 minor_hash; 264 struct rb_node rb_hash; 265 struct fname *next; 266 __u32 inode; 267 __u8 name_len; 268 __u8 file_type; 269 char name[0]; 270 }; 271 272 /* 273 * This functoin implements a non-recursive way of freeing all of the 274 * nodes in the red-black tree. 275 */ 276 static void free_rb_tree_fname(struct rb_root *root) 277 { 278 struct rb_node *n = root->rb_node; 279 struct rb_node *parent; 280 struct fname *fname; 281 282 while (n) { 283 /* Do the node's children first */ 284 if (n->rb_left) { 285 n = n->rb_left; 286 continue; 287 } 288 if (n->rb_right) { 289 n = n->rb_right; 290 continue; 291 } 292 /* 293 * The node has no children; free it, and then zero 294 * out parent's link to it. Finally go to the 295 * beginning of the loop and try to free the parent 296 * node. 297 */ 298 parent = rb_parent(n); 299 fname = rb_entry(n, struct fname, rb_hash); 300 while (fname) { 301 struct fname *old = fname; 302 fname = fname->next; 303 kfree(old); 304 } 305 if (!parent) 306 *root = RB_ROOT; 307 else if (parent->rb_left == n) 308 parent->rb_left = NULL; 309 else if (parent->rb_right == n) 310 parent->rb_right = NULL; 311 n = parent; 312 } 313 } 314 315 316 static struct dir_private_info *ext4_htree_create_dir_info(loff_t pos) 317 { 318 struct dir_private_info *p; 319 320 p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL); 321 if (!p) 322 return NULL; 323 p->curr_hash = pos2maj_hash(pos); 324 p->curr_minor_hash = pos2min_hash(pos); 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(KERN_ERR "EXT4-fs: call_filldir: called with " 412 "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; 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 = ext4_htree_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 if (call_filldir(filp, dirent, filldir, info->extra_fname)) 464 goto finished; 465 info->extra_fname = NULL; 466 goto next_node; 467 } else 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 next_node: 499 info->curr_node = rb_next(info->curr_node); 500 if (info->curr_node) { 501 fname = rb_entry(info->curr_node, struct fname, 502 rb_hash); 503 info->curr_hash = fname->hash; 504 info->curr_minor_hash = fname->minor_hash; 505 } else { 506 if (info->next_hash == ~0) { 507 filp->f_pos = EXT4_HTREE_EOF; 508 break; 509 } 510 info->curr_hash = info->next_hash; 511 info->curr_minor_hash = 0; 512 } 513 } 514 finished: 515 info->last_pos = filp->f_pos; 516 return 0; 517 } 518 519 static int ext4_release_dir(struct inode *inode, struct file *filp) 520 { 521 if (filp->private_data) 522 ext4_htree_free_dir_info(filp->private_data); 523 524 return 0; 525 } 526