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         int dir_has_error = 0;
 115         struct ext4_str fname_crypto_str = {.name = NULL, .len = 0};
 116
 117         if (ext4_encrypted_inode(inode)) {
 118                 err = ext4_get_encryption_info(inode);
 119                 if (err && err != -ENOKEY)
 120                         return err;
 121         }
 122
 123         if (is_dx_dir(inode)) {
 124                 err = ext4_dx_readdir(file, ctx);
 125                 if (err != ERR_BAD_DX_DIR) {
 126                         return err;
 127                 }
 128                 /* Can we just clear INDEX flag to ignore htree information? */
 129                 if (!ext4_has_metadata_csum(sb)) {
 130                         /*
 131                          * We don't set the inode dirty flag since it's not
 132                          * critical that it gets flushed back to the disk.
 133                          */
 134                         ext4_clear_inode_flag(inode, EXT4_INODE_INDEX);
 135                 }
 136         }
 137
 138         if (ext4_has_inline_data(inode)) {
 139                 int has_inline_data = 1;
 140                 err = ext4_read_inline_dir(file, ctx,
 141                                            &has_inline_data);
 142                 if (has_inline_data)
 143                         return err;
 144         }
 145
 146         if (ext4_encrypted_inode(inode)) {
 147                 err = ext4_fname_crypto_alloc_buffer(inode, EXT4_NAME_LEN,
 148                                                      &fname_crypto_str);
 149                 if (err < 0)
 150                         return err;
 151         }
 152
 153         offset = ctx->pos & (sb->s_blocksize - 1);
 154
 155         while (ctx->pos < inode->i_size) {
 156                 struct ext4_map_blocks map;
 157
 158                 map.m_lblk = ctx->pos >> EXT4_BLOCK_SIZE_BITS(sb);
 159                 map.m_len = 1;
 160                 err = ext4_map_blocks(NULL, inode, &map, 0);
 161                 if (err > 0) {
 162                         pgoff_t index = map.m_pblk >>
 163                                         (PAGE_CACHE_SHIFT - inode->i_blkbits);
 164                         if (!ra_has_index(&file->f_ra, index))
 165                                 page_cache_sync_readahead(
 166                                         sb->s_bdev->bd_inode->i_mapping,
 167                                         &file->f_ra, file,
 168                                         index, 1);
 169                         file->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT;
 170                         bh = ext4_bread(NULL, inode, map.m_lblk, 0);
 171                         if (IS_ERR(bh))
 172                                 return PTR_ERR(bh);
 173                 }
 174
 175                 if (!bh) {
 176                         if (!dir_has_error) {
 177                                 EXT4_ERROR_FILE(file, 0,
 178                                                 "directory contains a "
 179                                                 "hole at offset %llu",
 180                                            (unsigned long long) ctx->pos);
 181                                 dir_has_error = 1;
 182                         }
 183                         /* corrupt size?  Maybe no more blocks to read */
 184                         if (ctx->pos > inode->i_blocks << 9)
 185                                 break;
 186                         ctx->pos += sb->s_blocksize - offset;
 187                         continue;
 188                 }
 189
 190                 /* Check the checksum */
 191                 if (!buffer_verified(bh) &&
 192                     !ext4_dirent_csum_verify(inode,
 193                                 (struct ext4_dir_entry *)bh->b_data)) {
 194                         EXT4_ERROR_FILE(file, 0, "directory fails checksum "
 195                                         "at offset %llu",
 196                                         (unsigned long long)ctx->pos);
 197                         ctx->pos += sb->s_blocksize - offset;
 198                         brelse(bh);
 199                         bh = NULL;
 200                         continue;
 201                 }
 202                 set_buffer_verified(bh);
 203
 204                 /* If the dir block has changed since the last call to
 205                  * readdir(2), then we might be pointing to an invalid
 206                  * dirent right now.  Scan from the start of the block
 207                  * to make sure. */
 208                 if (file->f_version != inode->i_version) {
 209                         for (i = 0; i < sb->s_blocksize && i < offset; ) {
 210                                 de = (struct ext4_dir_entry_2 *)
 211                                         (bh->b_data + i);
 212                                 /* It's too expensive to do a full
 213                                  * dirent test each time round this
 214                                  * loop, but we do have to test at
 215                                  * least that it is non-zero.  A
 216                                  * failure will be detected in the
 217                                  * dirent test below. */
 218                                 if (ext4_rec_len_from_disk(de->rec_len,
 219                                         sb->s_blocksize) < EXT4_DIR_REC_LEN(1))
 220                                         break;
 221                                 i += ext4_rec_len_from_disk(de->rec_len,
 222                                                             sb->s_blocksize);
 223                         }
 224                         offset = i;
 225                         ctx->pos = (ctx->pos & ~(sb->s_blocksize - 1))
 226                                 | offset;
 227                         file->f_version = inode->i_version;
 228                 }
 229
 230                 while (ctx->pos < inode->i_size
 231                        && offset < sb->s_blocksize) {
 232                         de = (struct ext4_dir_entry_2 *) (bh->b_data + offset);
 233                         if (ext4_check_dir_entry(inode, file, de, bh,
 234                                                  bh->b_data, bh->b_size,
 235                                                  offset)) {
 236                                 /*
 237                                  * On error, skip to the next block
 238                                  */
 239                                 ctx->pos = (ctx->pos |
 240                                                 (sb->s_blocksize - 1)) + 1;
 241                                 break;
 242                         }
 243                         offset += ext4_rec_len_from_disk(de->rec_len,
 244                                         sb->s_blocksize);
 245                         if (le32_to_cpu(de->inode)) {
 246                                 if (!ext4_encrypted_inode(inode)) {
 247                                         if (!dir_emit(ctx, de->name,
 248                                             de->name_len,
 249                                             le32_to_cpu(de->inode),
 250                                             get_dtype(sb, de->file_type)))
 251                                                 goto done;
 252                                 } else {
 253                                         int save_len = fname_crypto_str.len;
 254
 255                                         /* Directory is encrypted */
 256                                         err = ext4_fname_disk_to_usr(inode,
 257                                                 NULL, de, &fname_crypto_str);
 258                                         fname_crypto_str.len = save_len;
 259                                         if (err < 0)
 260                                                 goto errout;
 261                                         if (!dir_emit(ctx,
 262                                             fname_crypto_str.name, err,
 263                                             le32_to_cpu(de->inode),
 264                                             get_dtype(sb, de->file_type)))
 265                                                 goto done;
 266                                 }
 267                         }
 268                         ctx->pos += ext4_rec_len_from_disk(de->rec_len,
 269                                                 sb->s_blocksize);
 270                 }
 271                 if ((ctx->pos < inode->i_size) && !dir_relax(inode))
 272                         goto done;
 273                 brelse(bh);
 274                 bh = NULL;
 275                 offset = 0;
 276         }
 277 done:
 278         err = 0;
 279 errout:
 280 #ifdef CONFIG_EXT4_FS_ENCRYPTION
 281         ext4_fname_crypto_free_buffer(&fname_crypto_str);
 282 #endif
 283         brelse(bh);
 284         return err;
 285 }
 286
 287 static inline int is_32bit_api(void)
 288 {
 289 #ifdef CONFIG_COMPAT
 290         return is_compat_task();
 291 #else
 292         return (BITS_PER_LONG == 32);
 293 #endif
 294 }
 295
 296 /*
 297  * These functions convert from the major/minor hash to an f_pos
 298  * value for dx directories
 299  *
 300  * Upper layer (for example NFS) should specify FMODE_32BITHASH or
 301  * FMODE_64BITHASH explicitly. On the other hand, we allow ext4 to be mounted
 302  * directly on both 32-bit and 64-bit nodes, under such case, neither
 303  * FMODE_32BITHASH nor FMODE_64BITHASH is specified.
 304  */
 305 static inline loff_t hash2pos(struct file *filp, __u32 major, __u32 minor)
 306 {
 307         if ((filp->f_mode & FMODE_32BITHASH) ||
 308             (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
 309                 return major >> 1;
 310         else
 311                 return ((__u64)(major >> 1) << 32) | (__u64)minor;
 312 }
 313
 314 static inline __u32 pos2maj_hash(struct file *filp, loff_t pos)
 315 {
 316         if ((filp->f_mode & FMODE_32BITHASH) ||
 317             (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
 318                 return (pos << 1) & 0xffffffff;
 319         else
 320                 return ((pos >> 32) << 1) & 0xffffffff;
 321 }
 322
 323 static inline __u32 pos2min_hash(struct file *filp, loff_t pos)
 324 {
 325         if ((filp->f_mode & FMODE_32BITHASH) ||
 326             (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
 327                 return 0;
 328         else
 329                 return pos & 0xffffffff;
 330 }
 331
 332 /*
 333  * Return 32- or 64-bit end-of-file for dx directories
 334  */
 335 static inline loff_t ext4_get_htree_eof(struct file *filp)
 336 {
 337         if ((filp->f_mode & FMODE_32BITHASH) ||
 338             (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
 339                 return EXT4_HTREE_EOF_32BIT;
 340         else
 341                 return EXT4_HTREE_EOF_64BIT;
 342 }
 343
 344
 345 /*
 346  * ext4_dir_llseek() calls generic_file_llseek_size to handle htree
 347  * directories, where the "offset" is in terms of the filename hash
 348  * value instead of the byte offset.
 349  *
 350  * Because we may return a 64-bit hash that is well beyond offset limits,
 351  * we need to pass the max hash as the maximum allowable offset in
 352  * the htree directory case.
 353  *
 354  * For non-htree, ext4_llseek already chooses the proper max offset.
 355  */
 356 static loff_t ext4_dir_llseek(struct file *file, loff_t offset, int whence)
 357 {
 358         struct inode *inode = file->f_mapping->host;
 359         int dx_dir = is_dx_dir(inode);
 360         loff_t htree_max = ext4_get_htree_eof(file);
 361
 362         if (likely(dx_dir))
 363                 return generic_file_llseek_size(file, offset, whence,
 364                                                     htree_max, htree_max);
 365         else
 366                 return ext4_llseek(file, offset, whence);
 367 }
 368
 369 /*
 370  * This structure holds the nodes of the red-black tree used to store
 371  * the directory entry in hash order.
 372  */
 373 struct fname {
 374         __u32           hash;
 375         __u32           minor_hash;
 376         struct rb_node  rb_hash;
 377         struct fname    *next;
 378         __u32           inode;
 379         __u8            name_len;
 380         __u8            file_type;
 381         char            name[0];
 382 };
 383
 384 /*
 385  * This functoin implements a non-recursive way of freeing all of the
 386  * nodes in the red-black tree.
 387  */
 388 static void free_rb_tree_fname(struct rb_root *root)
 389 {
 390         struct fname *fname, *next;
 391
 392         rbtree_postorder_for_each_entry_safe(fname, next, root, rb_hash)
 393                 while (fname) {
 394                         struct fname *old = fname;
 395                         fname = fname->next;
 396                         kfree(old);
 397                 }
 398
 399         *root = RB_ROOT;
 400 }
 401
 402
 403 static struct dir_private_info *ext4_htree_create_dir_info(struct file *filp,
 404                                                            loff_t pos)
 405 {
 406         struct dir_private_info *p;
 407
 408         p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL);
 409         if (!p)
 410                 return NULL;
 411         p->curr_hash = pos2maj_hash(filp, pos);
 412         p->curr_minor_hash = pos2min_hash(filp, pos);
 413         return p;
 414 }
 415
 416 void ext4_htree_free_dir_info(struct dir_private_info *p)
 417 {
 418         free_rb_tree_fname(&p->root);
 419         kfree(p);
 420 }
 421
 422 /*
 423  * Given a directory entry, enter it into the fname rb tree.
 424  *
 425  * When filename encryption is enabled, the dirent will hold the
 426  * encrypted filename, while the htree will hold decrypted filename.
 427  * The decrypted filename is passed in via ent_name.  parameter.
 428  */
 429 int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,
 430                              __u32 minor_hash,
 431                             struct ext4_dir_entry_2 *dirent,
 432                             struct ext4_str *ent_name)
 433 {
 434         struct rb_node **p, *parent = NULL;
 435         struct fname *fname, *new_fn;
 436         struct dir_private_info *info;
 437         int len;
 438
 439         info = dir_file->private_data;
 440         p = &info->root.rb_node;
 441
 442         /* Create and allocate the fname structure */
 443         len = sizeof(struct fname) + ent_name->len + 1;
 444         new_fn = kzalloc(len, GFP_KERNEL);
 445         if (!new_fn)
 446                 return -ENOMEM;
 447         new_fn->hash = hash;
 448         new_fn->minor_hash = minor_hash;
 449         new_fn->inode = le32_to_cpu(dirent->inode);
 450         new_fn->name_len = ent_name->len;
 451         new_fn->file_type = dirent->file_type;
 452         memcpy(new_fn->name, ent_name->name, ent_name->len);
 453         new_fn->name[ent_name->len] = 0;
 454
 455         while (*p) {
 456                 parent = *p;
 457                 fname = rb_entry(parent, struct fname, rb_hash);
 458
 459                 /*
 460                  * If the hash and minor hash match up, then we put
 461                  * them on a linked list.  This rarely happens...
 462                  */
 463                 if ((new_fn->hash == fname->hash) &&
 464                     (new_fn->minor_hash == fname->minor_hash)) {
 465                         new_fn->next = fname->next;
 466                         fname->next = new_fn;
 467                         return 0;
 468                 }
 469
 470                 if (new_fn->hash < fname->hash)
 471                         p = &(*p)->rb_left;
 472                 else if (new_fn->hash > fname->hash)
 473                         p = &(*p)->rb_right;
 474                 else if (new_fn->minor_hash < fname->minor_hash)
 475                         p = &(*p)->rb_left;
 476                 else /* if (new_fn->minor_hash > fname->minor_hash) */
 477                         p = &(*p)->rb_right;
 478         }
 479
 480         rb_link_node(&new_fn->rb_hash, parent, p);
 481         rb_insert_color(&new_fn->rb_hash, &info->root);
 482         return 0;
 483 }
 484
 485
 486
 487 /*
 488  * This is a helper function for ext4_dx_readdir.  It calls filldir
 489  * for all entres on the fname linked list.  (Normally there is only
 490  * one entry on the linked list, unless there are 62 bit hash collisions.)
 491  */
 492 static int call_filldir(struct file *file, struct dir_context *ctx,
 493                         struct fname *fname)
 494 {
 495         struct dir_private_info *info = file->private_data;
 496         struct inode *inode = file_inode(file);
 497         struct super_block *sb = inode->i_sb;
 498
 499         if (!fname) {
 500                 ext4_msg(sb, KERN_ERR, "%s:%d: inode #%lu: comm %s: "
 501                          "called with null fname?!?", __func__, __LINE__,
 502                          inode->i_ino, current->comm);
 503                 return 0;
 504         }
 505         ctx->pos = hash2pos(file, fname->hash, fname->minor_hash);
 506         while (fname) {
 507                 if (!dir_emit(ctx, fname->name,
 508                                 fname->name_len,
 509                                 fname->inode,
 510                                 get_dtype(sb, fname->file_type))) {
 511                         info->extra_fname = fname;
 512                         return 1;
 513                 }
 514                 fname = fname->next;
 515         }
 516         return 0;
 517 }
 518
 519 static int ext4_dx_readdir(struct file *file, struct dir_context *ctx)
 520 {
 521         struct dir_private_info *info = file->private_data;
 522         struct inode *inode = file_inode(file);
 523         struct fname *fname;
 524         int ret = 0;
 525
 526         if (!info) {
 527                 info = ext4_htree_create_dir_info(file, ctx->pos);
 528                 if (!info)
 529                         return -ENOMEM;
 530                 file->private_data = info;
 531         }
 532
 533         if (ctx->pos == ext4_get_htree_eof(file))
 534                 return 0;       /* EOF */
 535
 536         /* Some one has messed with f_pos; reset the world */
 537         if (info->last_pos != ctx->pos) {
 538                 free_rb_tree_fname(&info->root);
 539                 info->curr_node = NULL;
 540                 info->extra_fname = NULL;
 541                 info->curr_hash = pos2maj_hash(file, ctx->pos);
 542                 info->curr_minor_hash = pos2min_hash(file, ctx->pos);
 543         }
 544
 545         /*
 546          * If there are any leftover names on the hash collision
 547          * chain, return them first.
 548          */
 549         if (info->extra_fname) {
 550                 if (call_filldir(file, ctx, info->extra_fname))
 551                         goto finished;
 552                 info->extra_fname = NULL;
 553                 goto next_node;
 554         } else if (!info->curr_node)
 555                 info->curr_node = rb_first(&info->root);
 556
 557         while (1) {
 558                 /*
 559                  * Fill the rbtree if we have no more entries,
 560                  * or the inode has changed since we last read in the
 561                  * cached entries.
 562                  */
 563                 if ((!info->curr_node) ||
 564                     (file->f_version != inode->i_version)) {
 565                         info->curr_node = NULL;
 566                         free_rb_tree_fname(&info->root);
 567                         file->f_version = inode->i_version;
 568                         ret = ext4_htree_fill_tree(file, info->curr_hash,
 569                                                    info->curr_minor_hash,
 570                                                    &info->next_hash);
 571                         if (ret < 0)
 572                                 goto finished;
 573                         if (ret == 0) {
 574                                 ctx->pos = ext4_get_htree_eof(file);
 575                                 break;
 576                         }
 577                         info->curr_node = rb_first(&info->root);
 578                 }
 579
 580                 fname = rb_entry(info->curr_node, struct fname, rb_hash);
 581                 info->curr_hash = fname->hash;
 582                 info->curr_minor_hash = fname->minor_hash;
 583                 if (call_filldir(file, ctx, fname))
 584                         break;
 585         next_node:
 586                 info->curr_node = rb_next(info->curr_node);
 587                 if (info->curr_node) {
 588                         fname = rb_entry(info->curr_node, struct fname,
 589                                          rb_hash);
 590                         info->curr_hash = fname->hash;
 591                         info->curr_minor_hash = fname->minor_hash;
 592                 } else {
 593                         if (info->next_hash == ~0) {
 594                                 ctx->pos = ext4_get_htree_eof(file);
 595                                 break;
 596                         }
 597                         info->curr_hash = info->next_hash;
 598                         info->curr_minor_hash = 0;
 599                 }
 600         }
 601 finished:
 602         info->last_pos = ctx->pos;
 603         return ret < 0 ? ret : 0;
 604 }
 605
 606 static int ext4_dir_open(struct inode * inode, struct file * filp)
 607 {
 608         if (ext4_encrypted_inode(inode))
 609                 return ext4_get_encryption_info(inode) ? -EACCES : 0;
 610         return 0;
 611 }
 612
 613 static int ext4_release_dir(struct inode *inode, struct file *filp)
 614 {
 615         if (filp->private_data)
 616                 ext4_htree_free_dir_info(filp->private_data);
 617
 618         return 0;
 619 }
 620
 621 int ext4_check_all_de(struct inode *dir, struct buffer_head *bh, void *buf,
 622                       int buf_size)
 623 {
 624         struct ext4_dir_entry_2 *de;
 625         int nlen, rlen;
 626         unsigned int offset = 0;
 627         char *top;
 628
 629         de = (struct ext4_dir_entry_2 *)buf;
 630         top = buf + buf_size;
 631         while ((char *) de < top) {
 632                 if (ext4_check_dir_entry(dir, NULL, de, bh,
 633                                          buf, buf_size, offset))
 634                         return -EFSCORRUPTED;
 635                 nlen = EXT4_DIR_REC_LEN(de->name_len);
 636                 rlen = ext4_rec_len_from_disk(de->rec_len, buf_size);
 637                 de = (struct ext4_dir_entry_2 *)((char *)de + rlen);
 638                 offset += rlen;
 639         }
 640         if ((char *) de > top)
 641                 return -EFSCORRUPTED;
 642
 643         return 0;
 644 }
 645
 646 const struct file_operations ext4_dir_operations = {
 647         .llseek         = ext4_dir_llseek,
 648         .read           = generic_read_dir,
 649         .iterate        = ext4_readdir,
 650         .unlocked_ioctl = ext4_ioctl,
 651 #ifdef CONFIG_COMPAT
 652         .compat_ioctl   = ext4_compat_ioctl,
 653 #endif
 654         .fsync          = ext4_sync_file,
 655         .open           = ext4_dir_open,
 656         .release        = ext4_release_dir,
 657 };