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 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, 133 0, 0, 0); 134 if (err > 0) { 135 pgoff_t index = map_bh.b_blocknr >> 136 (PAGE_CACHE_SHIFT - inode->i_blkbits); 137 if (!ra_has_index(&filp->f_ra, index)) 138 page_cache_sync_readahead( 139 sb->s_bdev->bd_inode->i_mapping, 140 &filp->f_ra, filp, 141 index, 1); 142 filp->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT; 143 bh = ext4_bread(NULL, inode, blk, 0, &err); 144 } 145 146 /* 147 * We ignore I/O errors on directories so users have a chance 148 * of recovering data when there's a bad sector 149 */ 150 if (!bh) { 151 ext4_error (sb, "ext4_readdir", 152 "directory #%lu contains a hole at offset %lu", 153 inode->i_ino, (unsigned long)filp->f_pos); 154 /* corrupt size? Maybe no more blocks to read */ 155 if (filp->f_pos > inode->i_blocks << 9) 156 break; 157 filp->f_pos += sb->s_blocksize - offset; 158 continue; 159 } 160 161 revalidate: 162 /* If the dir block has changed since the last call to 163 * readdir(2), then we might be pointing to an invalid 164 * dirent right now. Scan from the start of the block 165 * to make sure. */ 166 if (filp->f_version != inode->i_version) { 167 for (i = 0; i < sb->s_blocksize && i < offset; ) { 168 de = (struct ext4_dir_entry_2 *) 169 (bh->b_data + i); 170 /* It's too expensive to do a full 171 * dirent test each time round this 172 * loop, but we do have to test at 173 * least that it is non-zero. A 174 * failure will be detected in the 175 * dirent test below. */ 176 if (ext4_rec_len_from_disk(de->rec_len) 177 < EXT4_DIR_REC_LEN(1)) 178 break; 179 i += ext4_rec_len_from_disk(de->rec_len); 180 } 181 offset = i; 182 filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1)) 183 | offset; 184 filp->f_version = inode->i_version; 185 } 186 187 while (!error && filp->f_pos < inode->i_size 188 && offset < sb->s_blocksize) { 189 de = (struct ext4_dir_entry_2 *) (bh->b_data + offset); 190 if (!ext4_check_dir_entry ("ext4_readdir", inode, de, 191 bh, offset)) { 192 /* 193 * On error, skip the f_pos to the next block 194 */ 195 filp->f_pos = (filp->f_pos | 196 (sb->s_blocksize - 1)) + 1; 197 brelse (bh); 198 ret = stored; 199 goto out; 200 } 201 offset += ext4_rec_len_from_disk(de->rec_len); 202 if (le32_to_cpu(de->inode)) { 203 /* We might block in the next section 204 * if the data destination is 205 * currently swapped out. So, use a 206 * version stamp to detect whether or 207 * not the directory has been modified 208 * during the copy operation. 209 */ 210 u64 version = filp->f_version; 211 212 error = filldir(dirent, de->name, 213 de->name_len, 214 filp->f_pos, 215 le32_to_cpu(de->inode), 216 get_dtype(sb, de->file_type)); 217 if (error) 218 break; 219 if (version != filp->f_version) 220 goto revalidate; 221 stored ++; 222 } 223 filp->f_pos += ext4_rec_len_from_disk(de->rec_len); 224 } 225 offset = 0; 226 brelse (bh); 227 } 228 out: 229 return ret; 230 } 231 232 /* 233 * These functions convert from the major/minor hash to an f_pos 234 * value. 235 * 236 * Currently we only use major hash numer. This is unfortunate, but 237 * on 32-bit machines, the same VFS interface is used for lseek and 238 * llseek, so if we use the 64 bit offset, then the 32-bit versions of 239 * lseek/telldir/seekdir will blow out spectacularly, and from within 240 * the ext2 low-level routine, we don't know if we're being called by 241 * a 64-bit version of the system call or the 32-bit version of the 242 * system call. Worse yet, NFSv2 only allows for a 32-bit readdir 243 * cookie. Sigh. 244 */ 245 #define hash2pos(major, minor) (major >> 1) 246 #define pos2maj_hash(pos) ((pos << 1) & 0xffffffff) 247 #define pos2min_hash(pos) (0) 248 249 /* 250 * This structure holds the nodes of the red-black tree used to store 251 * the directory entry in hash order. 252 */ 253 struct fname { 254 __u32 hash; 255 __u32 minor_hash; 256 struct rb_node rb_hash; 257 struct fname *next; 258 __u32 inode; 259 __u8 name_len; 260 __u8 file_type; 261 char name[0]; 262 }; 263 264 /* 265 * This functoin implements a non-recursive way of freeing all of the 266 * nodes in the red-black tree. 267 */ 268 static void free_rb_tree_fname(struct rb_root *root) 269 { 270 struct rb_node *n = root->rb_node; 271 struct rb_node *parent; 272 struct fname *fname; 273 274 while (n) { 275 /* Do the node's children first */ 276 if (n->rb_left) { 277 n = n->rb_left; 278 continue; 279 } 280 if (n->rb_right) { 281 n = n->rb_right; 282 continue; 283 } 284 /* 285 * The node has no children; free it, and then zero 286 * out parent's link to it. Finally go to the 287 * beginning of the loop and try to free the parent 288 * node. 289 */ 290 parent = rb_parent(n); 291 fname = rb_entry(n, struct fname, rb_hash); 292 while (fname) { 293 struct fname * old = fname; 294 fname = fname->next; 295 kfree (old); 296 } 297 if (!parent) 298 root->rb_node = NULL; 299 else if (parent->rb_left == n) 300 parent->rb_left = NULL; 301 else if (parent->rb_right == n) 302 parent->rb_right = NULL; 303 n = parent; 304 } 305 } 306 307 308 static struct dir_private_info *ext4_htree_create_dir_info(loff_t pos) 309 { 310 struct dir_private_info *p; 311 312 p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL); 313 if (!p) 314 return NULL; 315 p->curr_hash = pos2maj_hash(pos); 316 p->curr_minor_hash = pos2min_hash(pos); 317 return p; 318 } 319 320 void ext4_htree_free_dir_info(struct dir_private_info *p) 321 { 322 free_rb_tree_fname(&p->root); 323 kfree(p); 324 } 325 326 /* 327 * Given a directory entry, enter it into the fname rb tree. 328 */ 329 int ext4_htree_store_dirent(struct file *dir_file, __u32 hash, 330 __u32 minor_hash, 331 struct ext4_dir_entry_2 *dirent) 332 { 333 struct rb_node **p, *parent = NULL; 334 struct fname * fname, *new_fn; 335 struct dir_private_info *info; 336 int len; 337 338 info = (struct dir_private_info *) dir_file->private_data; 339 p = &info->root.rb_node; 340 341 /* Create and allocate the fname structure */ 342 len = sizeof(struct fname) + dirent->name_len + 1; 343 new_fn = kzalloc(len, GFP_KERNEL); 344 if (!new_fn) 345 return -ENOMEM; 346 new_fn->hash = hash; 347 new_fn->minor_hash = minor_hash; 348 new_fn->inode = le32_to_cpu(dirent->inode); 349 new_fn->name_len = dirent->name_len; 350 new_fn->file_type = dirent->file_type; 351 memcpy(new_fn->name, dirent->name, dirent->name_len); 352 new_fn->name[dirent->name_len] = 0; 353 354 while (*p) { 355 parent = *p; 356 fname = rb_entry(parent, struct fname, rb_hash); 357 358 /* 359 * If the hash and minor hash match up, then we put 360 * them on a linked list. This rarely happens... 361 */ 362 if ((new_fn->hash == fname->hash) && 363 (new_fn->minor_hash == fname->minor_hash)) { 364 new_fn->next = fname->next; 365 fname->next = new_fn; 366 return 0; 367 } 368 369 if (new_fn->hash < fname->hash) 370 p = &(*p)->rb_left; 371 else if (new_fn->hash > fname->hash) 372 p = &(*p)->rb_right; 373 else if (new_fn->minor_hash < fname->minor_hash) 374 p = &(*p)->rb_left; 375 else /* if (new_fn->minor_hash > fname->minor_hash) */ 376 p = &(*p)->rb_right; 377 } 378 379 rb_link_node(&new_fn->rb_hash, parent, p); 380 rb_insert_color(&new_fn->rb_hash, &info->root); 381 return 0; 382 } 383 384 385 386 /* 387 * This is a helper function for ext4_dx_readdir. It calls filldir 388 * for all entres on the fname linked list. (Normally there is only 389 * one entry on the linked list, unless there are 62 bit hash collisions.) 390 */ 391 static int call_filldir(struct file * filp, void * dirent, 392 filldir_t filldir, struct fname *fname) 393 { 394 struct dir_private_info *info = filp->private_data; 395 loff_t curr_pos; 396 struct inode *inode = filp->f_path.dentry->d_inode; 397 struct super_block * sb; 398 int error; 399 400 sb = inode->i_sb; 401 402 if (!fname) { 403 printk("call_filldir: called with null fname?!?\n"); 404 return 0; 405 } 406 curr_pos = hash2pos(fname->hash, fname->minor_hash); 407 while (fname) { 408 error = filldir(dirent, fname->name, 409 fname->name_len, curr_pos, 410 fname->inode, 411 get_dtype(sb, fname->file_type)); 412 if (error) { 413 filp->f_pos = curr_pos; 414 info->extra_fname = fname->next; 415 return error; 416 } 417 fname = fname->next; 418 } 419 return 0; 420 } 421 422 static int ext4_dx_readdir(struct file * filp, 423 void * dirent, filldir_t filldir) 424 { 425 struct dir_private_info *info = filp->private_data; 426 struct inode *inode = filp->f_path.dentry->d_inode; 427 struct fname *fname; 428 int ret; 429 430 if (!info) { 431 info = ext4_htree_create_dir_info(filp->f_pos); 432 if (!info) 433 return -ENOMEM; 434 filp->private_data = info; 435 } 436 437 if (filp->f_pos == EXT4_HTREE_EOF) 438 return 0; /* EOF */ 439 440 /* Some one has messed with f_pos; reset the world */ 441 if (info->last_pos != filp->f_pos) { 442 free_rb_tree_fname(&info->root); 443 info->curr_node = NULL; 444 info->extra_fname = NULL; 445 info->curr_hash = pos2maj_hash(filp->f_pos); 446 info->curr_minor_hash = pos2min_hash(filp->f_pos); 447 } 448 449 /* 450 * If there are any leftover names on the hash collision 451 * chain, return them first. 452 */ 453 if (info->extra_fname && 454 call_filldir(filp, dirent, filldir, info->extra_fname)) 455 goto finished; 456 457 if (!info->curr_node) 458 info->curr_node = rb_first(&info->root); 459 460 while (1) { 461 /* 462 * Fill the rbtree if we have no more entries, 463 * or the inode has changed since we last read in the 464 * cached entries. 465 */ 466 if ((!info->curr_node) || 467 (filp->f_version != inode->i_version)) { 468 info->curr_node = NULL; 469 free_rb_tree_fname(&info->root); 470 filp->f_version = inode->i_version; 471 ret = ext4_htree_fill_tree(filp, info->curr_hash, 472 info->curr_minor_hash, 473 &info->next_hash); 474 if (ret < 0) 475 return ret; 476 if (ret == 0) { 477 filp->f_pos = EXT4_HTREE_EOF; 478 break; 479 } 480 info->curr_node = rb_first(&info->root); 481 } 482 483 fname = rb_entry(info->curr_node, struct fname, rb_hash); 484 info->curr_hash = fname->hash; 485 info->curr_minor_hash = fname->minor_hash; 486 if (call_filldir(filp, dirent, filldir, fname)) 487 break; 488 489 info->curr_node = rb_next(info->curr_node); 490 if (!info->curr_node) { 491 if (info->next_hash == ~0) { 492 filp->f_pos = EXT4_HTREE_EOF; 493 break; 494 } 495 info->curr_hash = info->next_hash; 496 info->curr_minor_hash = 0; 497 } 498 } 499 finished: 500 info->last_pos = filp->f_pos; 501 return 0; 502 } 503 504 static int ext4_release_dir (struct inode * inode, struct file * filp) 505 { 506 if (filp->private_data) 507 ext4_htree_free_dir_info(filp->private_data); 508 509 return 0; 510 } 511