fs/ext4/dir.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  linux/fs/ext4/dir.c
   4  *
   5  * Copyright (C) 1992, 1993, 1994, 1995
   6  * Remy Card (card@masi.ibp.fr)
   7  * Laboratoire MASI - Institut Blaise Pascal
   8  * Universite Pierre et Marie Curie (Paris VI)
   9  *
  10  *  from
  11  *
  12  *  linux/fs/minix/dir.c
  13  *
  14  *  Copyright (C) 1991, 1992  Linus Torvalds
  15  *
  16  *  ext4 directory handling functions
  17  *
  18  *  Big-endian to little-endian byte-swapping/bitmaps by
  19  *        David S. Miller (davem@caip.rutgers.edu), 1995
  20  *
  21  * Hash Tree Directory indexing (c) 2001  Daniel Phillips
  22  *
  23  */
  24
  25 #include <linux/fs.h>
  26 #include <linux/buffer_head.h>
  27 #include <linux/slab.h>
  28 #include <linux/iversion.h>
  29 #include <linux/unicode.h>
  30 #include "ext4.h"
  31 #include "xattr.h"
  32
  33 static int ext4_dx_readdir(struct file *, struct dir_context *);
  34
  35 /**
  36  * is_dx_dir() - check if a directory is using htree indexing
  37  * @inode: directory inode
  38  *
  39  * Check if the given dir-inode refers to an htree-indexed directory
  40  * (or a directory which could potentially get converted to use htree
  41  * indexing).
  42  *
  43  * Return 1 if it is a dx dir, 0 if not
  44  */
  45 static int is_dx_dir(struct inode *inode)
  46 {
  47         struct super_block *sb = inode->i_sb;
  48
  49         if (ext4_has_feature_dir_index(inode->i_sb) &&
  50             ((ext4_test_inode_flag(inode, EXT4_INODE_INDEX)) ||
  51              ((inode->i_size >> sb->s_blocksize_bits) == 1) ||
  52              ext4_has_inline_data(inode)))
  53                 return 1;
  54
  55         return 0;
  56 }
  57
  58 /*
  59  * Return 0 if the directory entry is OK, and 1 if there is a problem
  60  *
  61  * Note: this is the opposite of what ext2 and ext3 historically returned...
  62  *
  63  * bh passed here can be an inode block or a dir data block, depending
  64  * on the inode inline data flag.
  65  */
  66 int __ext4_check_dir_entry(const char *function, unsigned int line,
  67                            struct inode *dir, struct file *filp,
  68                            struct ext4_dir_entry_2 *de,
  69                            struct buffer_head *bh, char *buf, int size,
  70                            unsigned int offset)
  71 {
  72         const char *error_msg = NULL;
  73         const int rlen = ext4_rec_len_from_disk(de->rec_len,
  74                                                 dir->i_sb->s_blocksize);
  75         const int next_offset = ((char *) de - buf) + rlen;
  76
  77         if (unlikely(rlen < EXT4_DIR_REC_LEN(1)))
  78                 error_msg = "rec_len is smaller than minimal";
  79         else if (unlikely(rlen % 4 != 0))
  80                 error_msg = "rec_len % 4 != 0";
  81         else if (unlikely(rlen < EXT4_DIR_REC_LEN(de->name_len)))
  82                 error_msg = "rec_len is too small for name_len";
  83         else if (unlikely(next_offset > size))
  84                 error_msg = "directory entry overrun";
  85         else if (unlikely(next_offset > size - EXT4_DIR_REC_LEN(1) &&
  86                           next_offset != size))
  87                 error_msg = "directory entry too close to block end";
  88         else if (unlikely(le32_to_cpu(de->inode) >
  89                         le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count)))
  90                 error_msg = "inode out of bounds";
  91         else
  92                 return 0;
  93
  94         if (filp)
  95                 ext4_error_file(filp, function, line, bh->b_blocknr,
  96                                 "bad entry in directory: %s - offset=%u, "
  97                                 "inode=%u, rec_len=%d, name_len=%d, size=%d",
  98                                 error_msg, offset, le32_to_cpu(de->inode),
  99                                 rlen, de->name_len, size);
 100         else
 101                 ext4_error_inode(dir, function, line, bh->b_blocknr,
 102                                 "bad entry in directory: %s - offset=%u, "
 103                                 "inode=%u, rec_len=%d, name_len=%d, size=%d",
 104                                  error_msg, offset, le32_to_cpu(de->inode),
 105                                  rlen, de->name_len, size);
 106
 107         return 1;
 108 }
 109
 110 static int ext4_readdir(struct file *file, struct dir_context *ctx)
 111 {
 112         unsigned int offset;
 113         int i;
 114         struct ext4_dir_entry_2 *de;
 115         int err;
 116         struct inode *inode = file_inode(file);
 117         struct super_block *sb = inode->i_sb;
 118         struct buffer_head *bh = NULL;
 119         struct fscrypt_str fstr = FSTR_INIT(NULL, 0);
 120
 121         err = fscrypt_prepare_readdir(inode);
 122         if (err)
 123                 return err;
 124
 125         if (is_dx_dir(inode)) {
 126                 err = ext4_dx_readdir(file, ctx);
 127                 if (err != ERR_BAD_DX_DIR) {
 128                         return err;
 129                 }
 130                 /* Can we just clear INDEX flag to ignore htree information? */
 131                 if (!ext4_has_metadata_csum(sb)) {
 132                         /*
 133                          * We don't set the inode dirty flag since it's not
 134                          * critical that it gets flushed back to the disk.
 135                          */
 136                         ext4_clear_inode_flag(inode, EXT4_INODE_INDEX);
 137                 }
 138         }
 139
 140         if (ext4_has_inline_data(inode)) {
 141                 int has_inline_data = 1;
 142                 err = ext4_read_inline_dir(file, ctx,
 143                                            &has_inline_data);
 144                 if (has_inline_data)
 145                         return err;
 146         }
 147
 148         if (IS_ENCRYPTED(inode)) {
 149                 err = fscrypt_fname_alloc_buffer(EXT4_NAME_LEN, &fstr);
 150                 if (err < 0)
 151                         return err;
 152         }
 153
 154         while (ctx->pos < inode->i_size) {
 155                 struct ext4_map_blocks map;
 156
 157                 if (fatal_signal_pending(current)) {
 158                         err = -ERESTARTSYS;
 159                         goto errout;
 160                 }
 161                 cond_resched();
 162                 offset = ctx->pos & (sb->s_blocksize - 1);
 163                 map.m_lblk = ctx->pos >> EXT4_BLOCK_SIZE_BITS(sb);
 164                 map.m_len = 1;
 165                 err = ext4_map_blocks(NULL, inode, &map, 0);
 166                 if (err == 0) {
 167                         /* m_len should never be zero but let's avoid
 168                          * an infinite loop if it somehow is */
 169                         if (map.m_len == 0)
 170                                 map.m_len = 1;
 171                         ctx->pos += map.m_len * sb->s_blocksize;
 172                         continue;
 173                 }
 174                 if (err > 0) {
 175                         pgoff_t index = map.m_pblk >>
 176                                         (PAGE_SHIFT - inode->i_blkbits);
 177                         if (!ra_has_index(&file->f_ra, index))
 178                                 page_cache_sync_readahead(
 179                                         sb->s_bdev->bd_inode->i_mapping,
 180                                         &file->f_ra, file,
 181                                         index, 1);
 182                         file->f_ra.prev_pos = (loff_t)index << PAGE_SHIFT;
 183                         bh = ext4_bread(NULL, inode, map.m_lblk, 0);
 184                         if (IS_ERR(bh)) {
 185                                 err = PTR_ERR(bh);
 186                                 bh = NULL;
 187                                 goto errout;
 188                         }
 189                 }
 190
 191                 if (!bh) {
 192                         /* corrupt size?  Maybe no more blocks to read */
 193                         if (ctx->pos > inode->i_blocks << 9)
 194                                 break;
 195                         ctx->pos += sb->s_blocksize - offset;
 196                         continue;
 197                 }
 198
 199                 /* Check the checksum */
 200                 if (!buffer_verified(bh) &&
 201                     !ext4_dirblock_csum_verify(inode, bh)) {
 202                         EXT4_ERROR_FILE(file, 0, "directory fails checksum "
 203                                         "at offset %llu",
 204                                         (unsigned long long)ctx->pos);
 205                         ctx->pos += sb->s_blocksize - offset;
 206                         brelse(bh);
 207                         bh = NULL;
 208                         continue;
 209                 }
 210                 set_buffer_verified(bh);
 211
 212                 /* If the dir block has changed since the last call to
 213                  * readdir(2), then we might be pointing to an invalid
 214                  * dirent right now.  Scan from the start of the block
 215                  * to make sure. */
 216                 if (!inode_eq_iversion(inode, file->f_version)) {
 217                         for (i = 0; i < sb->s_blocksize && i < offset; ) {
 218                                 de = (struct ext4_dir_entry_2 *)
 219                                         (bh->b_data + i);
 220                                 /* It's too expensive to do a full
 221                                  * dirent test each time round this
 222                                  * loop, but we do have to test at
 223                                  * least that it is non-zero.  A
 224                                  * failure will be detected in the
 225                                  * dirent test below. */
 226                                 if (ext4_rec_len_from_disk(de->rec_len,
 227                                         sb->s_blocksize) < EXT4_DIR_REC_LEN(1))
 228                                         break;
 229                                 i += ext4_rec_len_from_disk(de->rec_len,
 230                                                             sb->s_blocksize);
 231                         }
 232                         offset = i;
 233                         ctx->pos = (ctx->pos & ~(sb->s_blocksize - 1))
 234                                 | offset;
 235                         file->f_version = inode_query_iversion(inode);
 236                 }
 237
 238                 while (ctx->pos < inode->i_size
 239                        && offset < sb->s_blocksize) {
 240                         de = (struct ext4_dir_entry_2 *) (bh->b_data + offset);
 241                         if (ext4_check_dir_entry(inode, file, de, bh,
 242                                                  bh->b_data, bh->b_size,
 243                                                  offset)) {
 244                                 /*
 245                                  * On error, skip to the next block
 246                                  */
 247                                 ctx->pos = (ctx->pos |
 248                                                 (sb->s_blocksize - 1)) + 1;
 249                                 break;
 250                         }
 251                         offset += ext4_rec_len_from_disk(de->rec_len,
 252                                         sb->s_blocksize);
 253                         if (le32_to_cpu(de->inode)) {
 254                                 if (!IS_ENCRYPTED(inode)) {
 255                                         if (!dir_emit(ctx, de->name,
 256                                             de->name_len,
 257                                             le32_to_cpu(de->inode),
 258                                             get_dtype(sb, de->file_type)))
 259                                                 goto done;
 260                                 } else {
 261                                         int save_len = fstr.len;
 262                                         struct fscrypt_str de_name =
 263                                                         FSTR_INIT(de->name,
 264                                                                 de->name_len);
 265
 266                                         /* Directory is encrypted */
 267                                         err = fscrypt_fname_disk_to_usr(inode,
 268                                                 0, 0, &de_name, &fstr);
 269                                         de_name = fstr;
 270                                         fstr.len = save_len;
 271                                         if (err)
 272                                                 goto errout;
 273                                         if (!dir_emit(ctx,
 274                                             de_name.name, de_name.len,
 275                                             le32_to_cpu(de->inode),
 276                                             get_dtype(sb, de->file_type)))
 277                                                 goto done;
 278                                 }
 279                         }
 280                         ctx->pos += ext4_rec_len_from_disk(de->rec_len,
 281                                                 sb->s_blocksize);
 282                 }
 283                 if ((ctx->pos < inode->i_size) && !dir_relax_shared(inode))
 284                         goto done;
 285                 brelse(bh);
 286                 bh = NULL;
 287                 offset = 0;
 288         }
 289 done:
 290         err = 0;
 291 errout:
 292         fscrypt_fname_free_buffer(&fstr);
 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 ret, htree_max = ext4_get_htree_eof(file);
 371
 372         if (likely(dx_dir))
 373                 ret = generic_file_llseek_size(file, offset, whence,
 374                                                     htree_max, htree_max);
 375         else
 376                 ret = ext4_llseek(file, offset, whence);
 377         file->f_version = inode_peek_iversion(inode) - 1;
 378         return ret;
 379 }
 380
 381 /*
 382  * This structure holds the nodes of the red-black tree used to store
 383  * the directory entry in hash order.
 384  */
 385 struct fname {
 386         __u32           hash;
 387         __u32           minor_hash;
 388         struct rb_node  rb_hash;
 389         struct fname    *next;
 390         __u32           inode;
 391         __u8            name_len;
 392         __u8            file_type;
 393         char            name[];
 394 };
 395
 396 /*
 397  * This functoin implements a non-recursive way of freeing all of the
 398  * nodes in the red-black tree.
 399  */
 400 static void free_rb_tree_fname(struct rb_root *root)
 401 {
 402         struct fname *fname, *next;
 403
 404         rbtree_postorder_for_each_entry_safe(fname, next, root, rb_hash)
 405                 while (fname) {
 406                         struct fname *old = fname;
 407                         fname = fname->next;
 408                         kfree(old);
 409                 }
 410
 411         *root = RB_ROOT;
 412 }
 413
 414
 415 static struct dir_private_info *ext4_htree_create_dir_info(struct file *filp,
 416                                                            loff_t pos)
 417 {
 418         struct dir_private_info *p;
 419
 420         p = kzalloc(sizeof(*p), GFP_KERNEL);
 421         if (!p)
 422                 return NULL;
 423         p->curr_hash = pos2maj_hash(filp, pos);
 424         p->curr_minor_hash = pos2min_hash(filp, pos);
 425         return p;
 426 }
 427
 428 void ext4_htree_free_dir_info(struct dir_private_info *p)
 429 {
 430         free_rb_tree_fname(&p->root);
 431         kfree(p);
 432 }
 433
 434 /*
 435  * Given a directory entry, enter it into the fname rb tree.
 436  *
 437  * When filename encryption is enabled, the dirent will hold the
 438  * encrypted filename, while the htree will hold decrypted filename.
 439  * The decrypted filename is passed in via ent_name.  parameter.
 440  */
 441 int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,
 442                              __u32 minor_hash,
 443                             struct ext4_dir_entry_2 *dirent,
 444                             struct fscrypt_str *ent_name)
 445 {
 446         struct rb_node **p, *parent = NULL;
 447         struct fname *fname, *new_fn;
 448         struct dir_private_info *info;
 449         int len;
 450
 451         info = dir_file->private_data;
 452         p = &info->root.rb_node;
 453
 454         /* Create and allocate the fname structure */
 455         len = sizeof(struct fname) + ent_name->len + 1;
 456         new_fn = kzalloc(len, GFP_KERNEL);
 457         if (!new_fn)
 458                 return -ENOMEM;
 459         new_fn->hash = hash;
 460         new_fn->minor_hash = minor_hash;
 461         new_fn->inode = le32_to_cpu(dirent->inode);
 462         new_fn->name_len = ent_name->len;
 463         new_fn->file_type = dirent->file_type;
 464         memcpy(new_fn->name, ent_name->name, ent_name->len);
 465
 466         while (*p) {
 467                 parent = *p;
 468                 fname = rb_entry(parent, struct fname, rb_hash);
 469
 470                 /*
 471                  * If the hash and minor hash match up, then we put
 472                  * them on a linked list.  This rarely happens...
 473                  */
 474                 if ((new_fn->hash == fname->hash) &&
 475                     (new_fn->minor_hash == fname->minor_hash)) {
 476                         new_fn->next = fname->next;
 477                         fname->next = new_fn;
 478                         return 0;
 479                 }
 480
 481                 if (new_fn->hash < fname->hash)
 482                         p = &(*p)->rb_left;
 483                 else if (new_fn->hash > fname->hash)
 484                         p = &(*p)->rb_right;
 485                 else if (new_fn->minor_hash < fname->minor_hash)
 486                         p = &(*p)->rb_left;
 487                 else /* if (new_fn->minor_hash > fname->minor_hash) */
 488                         p = &(*p)->rb_right;
 489         }
 490
 491         rb_link_node(&new_fn->rb_hash, parent, p);
 492         rb_insert_color(&new_fn->rb_hash, &info->root);
 493         return 0;
 494 }
 495
 496
 497
 498 /*
 499  * This is a helper function for ext4_dx_readdir.  It calls filldir
 500  * for all entres on the fname linked list.  (Normally there is only
 501  * one entry on the linked list, unless there are 62 bit hash collisions.)
 502  */
 503 static int call_filldir(struct file *file, struct dir_context *ctx,
 504                         struct fname *fname)
 505 {
 506         struct dir_private_info *info = file->private_data;
 507         struct inode *inode = file_inode(file);
 508         struct super_block *sb = inode->i_sb;
 509
 510         if (!fname) {
 511                 ext4_msg(sb, KERN_ERR, "%s:%d: inode #%lu: comm %s: "
 512                          "called with null fname?!?", __func__, __LINE__,
 513                          inode->i_ino, current->comm);
 514                 return 0;
 515         }
 516         ctx->pos = hash2pos(file, fname->hash, fname->minor_hash);
 517         while (fname) {
 518                 if (!dir_emit(ctx, fname->name,
 519                                 fname->name_len,
 520                                 fname->inode,
 521                                 get_dtype(sb, fname->file_type))) {
 522                         info->extra_fname = fname;
 523                         return 1;
 524                 }
 525                 fname = fname->next;
 526         }
 527         return 0;
 528 }
 529
 530 static int ext4_dx_readdir(struct file *file, struct dir_context *ctx)
 531 {
 532         struct dir_private_info *info = file->private_data;
 533         struct inode *inode = file_inode(file);
 534         struct fname *fname;
 535         int     ret;
 536
 537         if (!info) {
 538                 info = ext4_htree_create_dir_info(file, ctx->pos);
 539                 if (!info)
 540                         return -ENOMEM;
 541                 file->private_data = info;
 542         }
 543
 544         if (ctx->pos == ext4_get_htree_eof(file))
 545                 return 0;       /* EOF */
 546
 547         /* Some one has messed with f_pos; reset the world */
 548         if (info->last_pos != ctx->pos) {
 549                 free_rb_tree_fname(&info->root);
 550                 info->curr_node = NULL;
 551                 info->extra_fname = NULL;
 552                 info->curr_hash = pos2maj_hash(file, ctx->pos);
 553                 info->curr_minor_hash = pos2min_hash(file, ctx->pos);
 554         }
 555
 556         /*
 557          * If there are any leftover names on the hash collision
 558          * chain, return them first.
 559          */
 560         if (info->extra_fname) {
 561                 if (call_filldir(file, ctx, info->extra_fname))
 562                         goto finished;
 563                 info->extra_fname = NULL;
 564                 goto next_node;
 565         } else if (!info->curr_node)
 566                 info->curr_node = rb_first(&info->root);
 567
 568         while (1) {
 569                 /*
 570                  * Fill the rbtree if we have no more entries,
 571                  * or the inode has changed since we last read in the
 572                  * cached entries.
 573                  */
 574                 if ((!info->curr_node) ||
 575                     !inode_eq_iversion(inode, file->f_version)) {
 576                         info->curr_node = NULL;
 577                         free_rb_tree_fname(&info->root);
 578                         file->f_version = inode_query_iversion(inode);
 579                         ret = ext4_htree_fill_tree(file, info->curr_hash,
 580                                                    info->curr_minor_hash,
 581                                                    &info->next_hash);
 582                         if (ret < 0)
 583                                 return ret;
 584                         if (ret == 0) {
 585                                 ctx->pos = ext4_get_htree_eof(file);
 586                                 break;
 587                         }
 588                         info->curr_node = rb_first(&info->root);
 589                 }
 590
 591                 fname = rb_entry(info->curr_node, struct fname, rb_hash);
 592                 info->curr_hash = fname->hash;
 593                 info->curr_minor_hash = fname->minor_hash;
 594                 if (call_filldir(file, ctx, fname))
 595                         break;
 596         next_node:
 597                 info->curr_node = rb_next(info->curr_node);
 598                 if (info->curr_node) {
 599                         fname = rb_entry(info->curr_node, struct fname,
 600                                          rb_hash);
 601                         info->curr_hash = fname->hash;
 602                         info->curr_minor_hash = fname->minor_hash;
 603                 } else {
 604                         if (info->next_hash == ~0) {
 605                                 ctx->pos = ext4_get_htree_eof(file);
 606                                 break;
 607                         }
 608                         info->curr_hash = info->next_hash;
 609                         info->curr_minor_hash = 0;
 610                 }
 611         }
 612 finished:
 613         info->last_pos = ctx->pos;
 614         return 0;
 615 }
 616
 617 static int ext4_release_dir(struct inode *inode, struct file *filp)
 618 {
 619         if (filp->private_data)
 620                 ext4_htree_free_dir_info(filp->private_data);
 621
 622         return 0;
 623 }
 624
 625 int ext4_check_all_de(struct inode *dir, struct buffer_head *bh, void *buf,
 626                       int buf_size)
 627 {
 628         struct ext4_dir_entry_2 *de;
 629         int rlen;
 630         unsigned int offset = 0;
 631         char *top;
 632
 633         de = (struct ext4_dir_entry_2 *)buf;
 634         top = buf + buf_size;
 635         while ((char *) de < top) {
 636                 if (ext4_check_dir_entry(dir, NULL, de, bh,
 637                                          buf, buf_size, offset))
 638                         return -EFSCORRUPTED;
 639                 rlen = ext4_rec_len_from_disk(de->rec_len, buf_size);
 640                 de = (struct ext4_dir_entry_2 *)((char *)de + rlen);
 641                 offset += rlen;
 642         }
 643         if ((char *) de > top)
 644                 return -EFSCORRUPTED;
 645
 646         return 0;
 647 }
 648
 649 const struct file_operations ext4_dir_operations = {
 650         .llseek         = ext4_dir_llseek,
 651         .read           = generic_read_dir,
 652         .iterate_shared = ext4_readdir,
 653         .unlocked_ioctl = ext4_ioctl,
 654 #ifdef CONFIG_COMPAT
 655         .compat_ioctl   = ext4_compat_ioctl,
 656 #endif
 657         .fsync          = ext4_sync_file,
 658         .release        = ext4_release_dir,
 659 };