fs/ext4/dir.c

   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/buffer_head.h>
  26 #include <linux/slab.h>
  27 #include "ext4.h"
  28 #include "xattr.h"
  29
  30 static int ext4_dx_readdir(struct file *, struct dir_context *);
  31
  32 /**
  33  * Check if the given dir-inode refers to an htree-indexed directory
  34  * (or a directory which could potentially get converted to use htree
  35  * indexing).
  36  *
  37  * Return 1 if it is a dx dir, 0 if not
  38  */
  39 static int is_dx_dir(struct inode *inode)
  40 {
  41         struct super_block *sb = inode->i_sb;
  42
  43         if (ext4_has_feature_dir_index(inode->i_sb) &&
  44             ((ext4_test_inode_flag(inode, EXT4_INODE_INDEX)) ||
  45              ((inode->i_size >> sb->s_blocksize_bits) == 1) ||
  46              ext4_has_inline_data(inode)))
  47                 return 1;
  48
  49         return 0;
  50 }
  51
  52 /*
  53  * Return 0 if the directory entry is OK, and 1 if there is a problem
  54  *
  55  * Note: this is the opposite of what ext2 and ext3 historically returned...
  56  *
  57  * bh passed here can be an inode block or a dir data block, depending
  58  * on the inode inline data flag.
  59  */
  60 int __ext4_check_dir_entry(const char *function, unsigned int line,
  61                            struct inode *dir, struct file *filp,
  62                            struct ext4_dir_entry_2 *de,
  63                            struct buffer_head *bh, char *buf, int size,
  64                            unsigned int offset)
  65 {
  66         const char *error_msg = NULL;
  67         const int rlen = ext4_rec_len_from_disk(de->rec_len,
  68                                                 dir->i_sb->s_blocksize);
  69
  70         if (unlikely(rlen < EXT4_DIR_REC_LEN(1)))
  71                 error_msg = "rec_len is smaller than minimal";
  72         else if (unlikely(rlen % 4 != 0))
  73                 error_msg = "rec_len % 4 != 0";
  74         else if (unlikely(rlen < EXT4_DIR_REC_LEN(de->name_len)))
  75                 error_msg = "rec_len is too small for name_len";
  76         else if (unlikely(((char *) de - buf) + rlen > size))
  77                 error_msg = "directory entry overrun";
  78         else if (unlikely(((char *) de - buf) + rlen >
  79                           size - EXT4_DIR_REC_LEN(1) &&
  80                           ((char *) de - buf) + rlen != size)) {
  81                 error_msg = "directory entry too close to block end";
  82         }
  83         else if (unlikely(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         else
  87                 return 0;
  88
  89         if (filp)
  90                 ext4_error_file(filp, function, line, bh->b_blocknr,
  91                                 "bad entry in directory: %s - offset=%u, "
  92                                 "inode=%u, rec_len=%d, name_len=%d, size=%d",
  93                                 error_msg, offset, le32_to_cpu(de->inode),
  94                                 rlen, de->name_len, size);
  95         else
  96                 ext4_error_inode(dir, function, line, bh->b_blocknr,
  97                                 "bad entry in directory: %s - offset=%u, "
  98                                 "inode=%u, rec_len=%d, name_len=%d, size=%d",
  99                                  error_msg, offset, le32_to_cpu(de->inode),
 100                                  rlen, de->name_len, size);
 101
 102         return 1;
 103 }
 104
 105 static int ext4_readdir(struct file *file, struct dir_context *ctx)
 106 {
 107         unsigned int offset;
 108         int i;
 109         struct ext4_dir_entry_2 *de;
 110         int err;
 111         struct inode *inode = file_inode(file);
 112         struct super_block *sb = inode->i_sb;
 113         struct buffer_head *bh = NULL;
 114         struct fscrypt_str fstr = FSTR_INIT(NULL, 0);
 115
 116         if (ext4_encrypted_inode(inode)) {
 117                 err = fscrypt_get_encryption_info(inode);
 118                 if (err && err != -ENOKEY)
 119                         return err;
 120         }
 121
 122         if (is_dx_dir(inode)) {
 123                 err = ext4_dx_readdir(file, ctx);
 124                 if (err != ERR_BAD_DX_DIR) {
 125                         return err;
 126                 }
 127                 /* Can we just clear INDEX flag to ignore htree information? */
 128                 if (!ext4_has_metadata_csum(sb)) {
 129                         /*
 130                          * We don't set the inode dirty flag since it's not
 131                          * critical that it gets flushed back to the disk.
 132                          */
 133                         ext4_clear_inode_flag(inode, EXT4_INODE_INDEX);
 134                 }
 135         }
 136
 137         if (ext4_has_inline_data(inode)) {
 138                 int has_inline_data = 1;
 139                 err = ext4_read_inline_dir(file, ctx,
 140                                            &has_inline_data);
 141                 if (has_inline_data)
 142                         return err;
 143         }
 144
 145         if (ext4_encrypted_inode(inode)) {
 146                 err = fscrypt_fname_alloc_buffer(inode, EXT4_NAME_LEN, &fstr);
 147                 if (err < 0)
 148                         return err;
 149         }
 150
 151         while (ctx->pos < inode->i_size) {
 152                 struct ext4_map_blocks map;
 153
 154                 if (fatal_signal_pending(current)) {
 155                         err = -ERESTARTSYS;
 156                         goto errout;
 157                 }
 158                 cond_resched();
 159                 offset = ctx->pos & (sb->s_blocksize - 1);
 160                 map.m_lblk = ctx->pos >> EXT4_BLOCK_SIZE_BITS(sb);
 161                 map.m_len = 1;
 162                 err = ext4_map_blocks(NULL, inode, &map, 0);
 163                 if (err == 0) {
 164                         /* m_len should never be zero but let's avoid
 165                          * an infinite loop if it somehow is */
 166                         if (map.m_len == 0)
 167                                 map.m_len = 1;
 168                         ctx->pos += map.m_len * sb->s_blocksize;
 169                         continue;
 170                 }
 171                 if (err > 0) {
 172                         pgoff_t index = map.m_pblk >>
 173                                         (PAGE_SHIFT - inode->i_blkbits);
 174                         if (!ra_has_index(&file->f_ra, index))
 175                                 page_cache_sync_readahead(
 176                                         sb->s_bdev->bd_inode->i_mapping,
 177                                         &file->f_ra, file,
 178                                         index, 1);
 179                         file->f_ra.prev_pos = (loff_t)index << PAGE_SHIFT;
 180                         bh = ext4_bread(NULL, inode, map.m_lblk, 0);
 181                         if (IS_ERR(bh)) {
 182                                 err = PTR_ERR(bh);
 183                                 bh = NULL;
 184                                 goto errout;
 185                         }
 186                 }
 187
 188                 if (!bh) {
 189                         /* corrupt size?  Maybe no more blocks to read */
 190                         if (ctx->pos > inode->i_blocks << 9)
 191                                 break;
 192                         ctx->pos += sb->s_blocksize - offset;
 193                         continue;
 194                 }
 195
 196                 /* Check the checksum */
 197                 if (!buffer_verified(bh) &&
 198                     !ext4_dirent_csum_verify(inode,
 199                                 (struct ext4_dir_entry *)bh->b_data)) {
 200                         EXT4_ERROR_FILE(file, 0, "directory fails checksum "
 201                                         "at offset %llu",
 202                                         (unsigned long long)ctx->pos);
 203                         ctx->pos += sb->s_blocksize - offset;
 204                         brelse(bh);
 205                         bh = NULL;
 206                         continue;
 207                 }
 208                 set_buffer_verified(bh);
 209
 210                 /* If the dir block has changed since the last call to
 211                  * readdir(2), then we might be pointing to an invalid
 212                  * dirent right now.  Scan from the start of the block
 213                  * to make sure. */
 214                 if (file->f_version != inode->i_version) {
 215                         for (i = 0; i < sb->s_blocksize && i < offset; ) {
 216                                 de = (struct ext4_dir_entry_2 *)
 217                                         (bh->b_data + i);
 218                                 /* It's too expensive to do a full
 219                                  * dirent test each time round this
 220                                  * loop, but we do have to test at
 221                                  * least that it is non-zero.  A
 222                                  * failure will be detected in the
 223                                  * dirent test below. */
 224                                 if (ext4_rec_len_from_disk(de->rec_len,
 225                                         sb->s_blocksize) < EXT4_DIR_REC_LEN(1))
 226                                         break;
 227                                 i += ext4_rec_len_from_disk(de->rec_len,
 228                                                             sb->s_blocksize);
 229                         }
 230                         offset = i;
 231                         ctx->pos = (ctx->pos & ~(sb->s_blocksize - 1))
 232                                 | offset;
 233                         file->f_version = inode->i_version;
 234                 }
 235
 236                 while (ctx->pos < inode->i_size
 237                        && offset < sb->s_blocksize) {
 238                         de = (struct ext4_dir_entry_2 *) (bh->b_data + offset);
 239                         if (ext4_check_dir_entry(inode, file, de, bh,
 240                                                  bh->b_data, bh->b_size,
 241                                                  offset)) {
 242                                 /*
 243                                  * On error, skip to the next block
 244                                  */
 245                                 ctx->pos = (ctx->pos |
 246                                                 (sb->s_blocksize - 1)) + 1;
 247                                 break;
 248                         }
 249                         offset += ext4_rec_len_from_disk(de->rec_len,
 250                                         sb->s_blocksize);
 251                         if (le32_to_cpu(de->inode)) {
 252                                 if (!ext4_encrypted_inode(inode)) {
 253                                         if (!dir_emit(ctx, de->name,
 254                                             de->name_len,
 255                                             le32_to_cpu(de->inode),
 256                                             get_dtype(sb, de->file_type)))
 257                                                 goto done;
 258                                 } else {
 259                                         int save_len = fstr.len;
 260                                         struct fscrypt_str de_name =
 261                                                         FSTR_INIT(de->name,
 262                                                                 de->name_len);
 263
 264                                         /* Directory is encrypted */
 265                                         err = fscrypt_fname_disk_to_usr(inode,
 266                                                 0, 0, &de_name, &fstr);
 267                                         de_name = fstr;
 268                                         fstr.len = save_len;
 269                                         if (err)
 270                                                 goto errout;
 271                                         if (!dir_emit(ctx,
 272                                             de_name.name, de_name.len,
 273                                             le32_to_cpu(de->inode),
 274                                             get_dtype(sb, de->file_type)))
 275                                                 goto done;
 276                                 }
 277                         }
 278                         ctx->pos += ext4_rec_len_from_disk(de->rec_len,
 279                                                 sb->s_blocksize);
 280                 }
 281                 if ((ctx->pos < inode->i_size) && !dir_relax_shared(inode))
 282                         goto done;
 283                 brelse(bh);
 284                 bh = NULL;
 285                 offset = 0;
 286         }
 287 done:
 288         err = 0;
 289 errout:
 290 #ifdef CONFIG_EXT4_FS_ENCRYPTION
 291         fscrypt_fname_free_buffer(&fstr);
 292 #endif
 293         brelse(bh);
 294         return err;
 295 }
 296
 297 static inline int is_32bit_api(void)
 298 {
 299 #ifdef CONFIG_COMPAT
 300         return in_compat_syscall();
 301 #else
 302         return (BITS_PER_LONG == 32);
 303 #endif
 304 }
 305
 306 /*
 307  * These functions convert from the major/minor hash to an f_pos
 308  * value for dx directories
 309  *
 310  * Upper layer (for example NFS) should specify FMODE_32BITHASH or
 311  * FMODE_64BITHASH explicitly. On the other hand, we allow ext4 to be mounted
 312  * directly on both 32-bit and 64-bit nodes, under such case, neither
 313  * FMODE_32BITHASH nor FMODE_64BITHASH is specified.
 314  */
 315 static inline loff_t hash2pos(struct file *filp, __u32 major, __u32 minor)
 316 {
 317         if ((filp->f_mode & FMODE_32BITHASH) ||
 318             (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
 319                 return major >> 1;
 320         else
 321                 return ((__u64)(major >> 1) << 32) | (__u64)minor;
 322 }
 323
 324 static inline __u32 pos2maj_hash(struct file *filp, loff_t pos)
 325 {
 326         if ((filp->f_mode & FMODE_32BITHASH) ||
 327             (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
 328                 return (pos << 1) & 0xffffffff;
 329         else
 330                 return ((pos >> 32) << 1) & 0xffffffff;
 331 }
 332
 333 static inline __u32 pos2min_hash(struct file *filp, loff_t pos)
 334 {
 335         if ((filp->f_mode & FMODE_32BITHASH) ||
 336             (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
 337                 return 0;
 338         else
 339                 return pos & 0xffffffff;
 340 }
 341
 342 /*
 343  * Return 32- or 64-bit end-of-file for dx directories
 344  */
 345 static inline loff_t ext4_get_htree_eof(struct file *filp)
 346 {
 347         if ((filp->f_mode & FMODE_32BITHASH) ||
 348             (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
 349                 return EXT4_HTREE_EOF_32BIT;
 350         else
 351                 return EXT4_HTREE_EOF_64BIT;
 352 }
 353
 354
 355 /*
 356  * ext4_dir_llseek() calls generic_file_llseek_size to handle htree
 357  * directories, where the "offset" is in terms of the filename hash
 358  * value instead of the byte offset.
 359  *
 360  * Because we may return a 64-bit hash that is well beyond offset limits,
 361  * we need to pass the max hash as the maximum allowable offset in
 362  * the htree directory case.
 363  *
 364  * For non-htree, ext4_llseek already chooses the proper max offset.
 365  */
 366 static loff_t ext4_dir_llseek(struct file *file, loff_t offset, int whence)
 367 {
 368         struct inode *inode = file->f_mapping->host;
 369         int dx_dir = is_dx_dir(inode);
 370         loff_t htree_max = ext4_get_htree_eof(file);
 371
 372         if (likely(dx_dir))
 373                 return generic_file_llseek_size(file, offset, whence,
 374                                                     htree_max, htree_max);
 375         else
 376                 return ext4_llseek(file, offset, whence);
 377 }
 378
 379 /*
 380  * This structure holds the nodes of the red-black tree used to store
 381  * the directory entry in hash order.
 382  */
 383 struct fname {
 384         __u32           hash;
 385         __u32           minor_hash;
 386         struct rb_node  rb_hash;
 387         struct fname    *next;
 388         __u32           inode;
 389         __u8            name_len;
 390         __u8            file_type;
 391         char            name[0];
 392 };
 393
 394 /*
 395  * This functoin implements a non-recursive way of freeing all of the
 396  * nodes in the red-black tree.
 397  */
 398 static void free_rb_tree_fname(struct rb_root *root)
 399 {
 400         struct fname *fname, *next;
 401
 402         rbtree_postorder_for_each_entry_safe(fname, next, root, rb_hash)
 403                 while (fname) {
 404                         struct fname *old = fname;
 405                         fname = fname->next;
 406                         kfree(old);
 407                 }
 408
 409         *root = RB_ROOT;
 410 }
 411
 412
 413 static struct dir_private_info *ext4_htree_create_dir_info(struct file *filp,
 414                                                            loff_t pos)
 415 {
 416         struct dir_private_info *p;
 417
 418         p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL);
 419         if (!p)
 420                 return NULL;
 421         p->curr_hash = pos2maj_hash(filp, pos);
 422         p->curr_minor_hash = pos2min_hash(filp, pos);
 423         return p;
 424 }
 425
 426 void ext4_htree_free_dir_info(struct dir_private_info *p)
 427 {
 428         free_rb_tree_fname(&p->root);
 429         kfree(p);
 430 }
 431
 432 /*
 433  * Given a directory entry, enter it into the fname rb tree.
 434  *
 435  * When filename encryption is enabled, the dirent will hold the
 436  * encrypted filename, while the htree will hold decrypted filename.
 437  * The decrypted filename is passed in via ent_name.  parameter.
 438  */
 439 int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,
 440                              __u32 minor_hash,
 441                             struct ext4_dir_entry_2 *dirent,
 442                             struct fscrypt_str *ent_name)
 443 {
 444         struct rb_node **p, *parent = NULL;
 445         struct fname *fname, *new_fn;
 446         struct dir_private_info *info;
 447         int len;
 448
 449         info = dir_file->private_data;
 450         p = &info->root.rb_node;
 451
 452         /* Create and allocate the fname structure */
 453         len = sizeof(struct fname) + ent_name->len + 1;
 454         new_fn = kzalloc(len, GFP_KERNEL);
 455         if (!new_fn)
 456                 return -ENOMEM;
 457         new_fn->hash = hash;
 458         new_fn->minor_hash = minor_hash;
 459         new_fn->inode = le32_to_cpu(dirent->inode);
 460         new_fn->name_len = ent_name->len;
 461         new_fn->file_type = dirent->file_type;
 462         memcpy(new_fn->name, ent_name->name, ent_name->len);
 463         new_fn->name[ent_name->len] = 0;
 464
 465         while (*p) {
 466                 parent = *p;
 467                 fname = rb_entry(parent, struct fname, rb_hash);
 468
 469                 /*
 470                  * If the hash and minor hash match up, then we put
 471                  * them on a linked list.  This rarely happens...
 472                  */
 473                 if ((new_fn->hash == fname->hash) &&
 474                     (new_fn->minor_hash == fname->minor_hash)) {
 475                         new_fn->next = fname->next;
 476                         fname->next = new_fn;
 477                         return 0;
 478                 }
 479
 480                 if (new_fn->hash < fname->hash)
 481                         p = &(*p)->rb_left;
 482                 else if (new_fn->hash > fname->hash)
 483                         p = &(*p)->rb_right;
 484                 else if (new_fn->minor_hash < fname->minor_hash)
 485                         p = &(*p)->rb_left;
 486                 else /* if (new_fn->minor_hash > fname->minor_hash) */
 487                         p = &(*p)->rb_right;
 488         }
 489
 490         rb_link_node(&new_fn->rb_hash, parent, p);
 491         rb_insert_color(&new_fn->rb_hash, &info->root);
 492         return 0;
 493 }
 494
 495
 496
 497 /*
 498  * This is a helper function for ext4_dx_readdir.  It calls filldir
 499  * for all entres on the fname linked list.  (Normally there is only
 500  * one entry on the linked list, unless there are 62 bit hash collisions.)
 501  */
 502 static int call_filldir(struct file *file, struct dir_context *ctx,
 503                         struct fname *fname)
 504 {
 505         struct dir_private_info *info = file->private_data;
 506         struct inode *inode = file_inode(file);
 507         struct super_block *sb = inode->i_sb;
 508
 509         if (!fname) {
 510                 ext4_msg(sb, KERN_ERR, "%s:%d: inode #%lu: comm %s: "
 511                          "called with null fname?!?", __func__, __LINE__,
 512                          inode->i_ino, current->comm);
 513                 return 0;
 514         }
 515         ctx->pos = hash2pos(file, fname->hash, fname->minor_hash);
 516         while (fname) {
 517                 if (!dir_emit(ctx, fname->name,
 518                                 fname->name_len,
 519                                 fname->inode,
 520                                 get_dtype(sb, fname->file_type))) {
 521                         info->extra_fname = fname;
 522                         return 1;
 523                 }
 524                 fname = fname->next;
 525         }
 526         return 0;
 527 }
 528
 529 static int ext4_dx_readdir(struct file *file, struct dir_context *ctx)
 530 {
 531         struct dir_private_info *info = file->private_data;
 532         struct inode *inode = file_inode(file);
 533         struct fname *fname;
 534         int ret = 0;
 535
 536         if (!info) {
 537                 info = ext4_htree_create_dir_info(file, ctx->pos);
 538                 if (!info)
 539                         return -ENOMEM;
 540                 file->private_data = info;
 541         }
 542
 543         if (ctx->pos == ext4_get_htree_eof(file))
 544                 return 0;       /* EOF */
 545
 546         /* Some one has messed with f_pos; reset the world */
 547         if (info->last_pos != ctx->pos) {
 548                 free_rb_tree_fname(&info->root);
 549                 info->curr_node = NULL;
 550                 info->extra_fname = NULL;
 551                 info->curr_hash = pos2maj_hash(file, ctx->pos);
 552                 info->curr_minor_hash = pos2min_hash(file, ctx->pos);
 553         }
 554
 555         /*
 556          * If there are any leftover names on the hash collision
 557          * chain, return them first.
 558          */
 559         if (info->extra_fname) {
 560                 if (call_filldir(file, ctx, info->extra_fname))
 561                         goto finished;
 562                 info->extra_fname = NULL;
 563                 goto next_node;
 564         } else if (!info->curr_node)
 565                 info->curr_node = rb_first(&info->root);
 566
 567         while (1) {
 568                 /*
 569                  * Fill the rbtree if we have no more entries,
 570                  * or the inode has changed since we last read in the
 571                  * cached entries.
 572                  */
 573                 if ((!info->curr_node) ||
 574                     (file->f_version != inode->i_version)) {
 575                         info->curr_node = NULL;
 576                         free_rb_tree_fname(&info->root);
 577                         file->f_version = inode->i_version;
 578                         ret = ext4_htree_fill_tree(file, info->curr_hash,
 579                                                    info->curr_minor_hash,
 580                                                    &info->next_hash);
 581                         if (ret < 0)
 582                                 goto finished;
 583                         if (ret == 0) {
 584                                 ctx->pos = ext4_get_htree_eof(file);
 585                                 break;
 586                         }
 587                         info->curr_node = rb_first(&info->root);
 588                 }
 589
 590                 fname = rb_entry(info->curr_node, struct fname, rb_hash);
 591                 info->curr_hash = fname->hash;
 592                 info->curr_minor_hash = fname->minor_hash;
 593                 if (call_filldir(file, ctx, fname))
 594                         break;
 595         next_node:
 596                 info->curr_node = rb_next(info->curr_node);
 597                 if (info->curr_node) {
 598                         fname = rb_entry(info->curr_node, struct fname,
 599                                          rb_hash);
 600                         info->curr_hash = fname->hash;
 601                         info->curr_minor_hash = fname->minor_hash;
 602                 } else {
 603                         if (info->next_hash == ~0) {
 604                                 ctx->pos = ext4_get_htree_eof(file);
 605                                 break;
 606                         }
 607                         info->curr_hash = info->next_hash;
 608                         info->curr_minor_hash = 0;
 609                 }
 610         }
 611 finished:
 612         info->last_pos = ctx->pos;
 613         return ret < 0 ? ret : 0;
 614 }
 615
 616 static int ext4_dir_open(struct inode * inode, struct file * filp)
 617 {
 618         if (ext4_encrypted_inode(inode))
 619                 return fscrypt_get_encryption_info(inode) ? -EACCES : 0;
 620         return 0;
 621 }
 622
 623 static int ext4_release_dir(struct inode *inode, struct file *filp)
 624 {
 625         if (filp->private_data)
 626                 ext4_htree_free_dir_info(filp->private_data);
 627
 628         return 0;
 629 }
 630
 631 int ext4_check_all_de(struct inode *dir, struct buffer_head *bh, void *buf,
 632                       int buf_size)
 633 {
 634         struct ext4_dir_entry_2 *de;
 635         int rlen;
 636         unsigned int offset = 0;
 637         char *top;
 638
 639         de = (struct ext4_dir_entry_2 *)buf;
 640         top = buf + buf_size;
 641         while ((char *) de < top) {
 642                 if (ext4_check_dir_entry(dir, NULL, de, bh,
 643                                          buf, buf_size, offset))
 644                         return -EFSCORRUPTED;
 645                 rlen = ext4_rec_len_from_disk(de->rec_len, buf_size);
 646                 de = (struct ext4_dir_entry_2 *)((char *)de + rlen);
 647                 offset += rlen;
 648         }
 649         if ((char *) de > top)
 650                 return -EFSCORRUPTED;
 651
 652         return 0;
 653 }
 654
 655 const struct file_operations ext4_dir_operations = {
 656         .llseek         = ext4_dir_llseek,
 657         .read           = generic_read_dir,
 658         .iterate_shared = ext4_readdir,
 659         .unlocked_ioctl = ext4_ioctl,
 660 #ifdef CONFIG_COMPAT
 661         .compat_ioctl   = ext4_compat_ioctl,
 662 #endif
 663         .fsync          = ext4_sync_file,
 664         .open           = ext4_dir_open,
 665         .release        = ext4_release_dir,
 666 };