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 across range";
  78         else if (unlikely(le32_to_cpu(de->inode) >
  79                         le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count)))
  80                 error_msg = "inode out of bounds";
  81         else
  82                 return 0;
  83
  84         if (filp)
  85                 ext4_error_file(filp, function, line, bh->b_blocknr,
  86                                 "bad entry in directory: %s - offset=%u(%u), "
  87                                 "inode=%u, rec_len=%d, name_len=%d",
  88                                 error_msg, (unsigned) (offset % size),
  89                                 offset, le32_to_cpu(de->inode),
  90                                 rlen, de->name_len);
  91         else
  92                 ext4_error_inode(dir, function, line, bh->b_blocknr,
  93                                 "bad entry in directory: %s - offset=%u(%u), "
  94                                 "inode=%u, rec_len=%d, name_len=%d",
  95                                 error_msg, (unsigned) (offset % size),
  96                                 offset, le32_to_cpu(de->inode),
  97                                 rlen, de->name_len);
  98
  99         return 1;
 100 }
 101
 102 static int ext4_readdir(struct file *file, struct dir_context *ctx)
 103 {
 104         unsigned int offset;
 105         int i;
 106         struct ext4_dir_entry_2 *de;
 107         int err;
 108         struct inode *inode = file_inode(file);
 109         struct super_block *sb = inode->i_sb;
 110         struct buffer_head *bh = NULL;
 111         int dir_has_error = 0;
 112         struct ext4_str fname_crypto_str = {.name = NULL, .len = 0};
 113
 114         if (ext4_encrypted_inode(inode)) {
 115                 err = ext4_get_encryption_info(inode);
 116                 if (err && err != -ENOKEY)
 117                         return err;
 118         }
 119
 120         if (is_dx_dir(inode)) {
 121                 err = ext4_dx_readdir(file, ctx);
 122                 if (err != ERR_BAD_DX_DIR) {
 123                         return err;
 124                 }
 125                 /*
 126                  * We don't set the inode dirty flag since it's not
 127                  * critical that it get flushed back to the disk.
 128                  */
 129                 ext4_clear_inode_flag(file_inode(file),
 130                                       EXT4_INODE_INDEX);
 131         }
 132
 133         if (ext4_has_inline_data(inode)) {
 134                 int has_inline_data = 1;
 135                 err = ext4_read_inline_dir(file, ctx,
 136                                            &has_inline_data);
 137                 if (has_inline_data)
 138                         return err;
 139         }
 140
 141         if (ext4_encrypted_inode(inode)) {
 142                 err = ext4_fname_crypto_alloc_buffer(inode, EXT4_NAME_LEN,
 143                                                      &fname_crypto_str);
 144                 if (err < 0)
 145                         return err;
 146         }
 147
 148         offset = ctx->pos & (sb->s_blocksize - 1);
 149
 150         while (ctx->pos < inode->i_size) {
 151                 struct ext4_map_blocks map;
 152
 153                 if (fatal_signal_pending(current)) {
 154                         err = -ERESTARTSYS;
 155                         goto errout;
 156                 }
 157                 cond_resched();
 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_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_SHIFT;
 170                         bh = ext4_bread(NULL, inode, map.m_lblk, 0);
 171                         if (IS_ERR(bh)) {
 172                                 err = PTR_ERR(bh);
 173                                 bh = NULL;
 174                                 goto errout;
 175                         }
 176                 }
 177
 178                 if (!bh) {
 179                         if (!dir_has_error) {
 180                                 EXT4_ERROR_FILE(file, 0,
 181                                                 "directory contains a "
 182                                                 "hole at offset %llu",
 183                                            (unsigned long long) ctx->pos);
 184                                 dir_has_error = 1;
 185                         }
 186                         /* corrupt size?  Maybe no more blocks to read */
 187                         if (ctx->pos > inode->i_blocks << 9)
 188                                 break;
 189                         ctx->pos += sb->s_blocksize - offset;
 190                         continue;
 191                 }
 192
 193                 /* Check the checksum */
 194                 if (!buffer_verified(bh) &&
 195                     !ext4_dirent_csum_verify(inode,
 196                                 (struct ext4_dir_entry *)bh->b_data)) {
 197                         EXT4_ERROR_FILE(file, 0, "directory fails checksum "
 198                                         "at offset %llu",
 199                                         (unsigned long long)ctx->pos);
 200                         ctx->pos += sb->s_blocksize - offset;
 201                         brelse(bh);
 202                         bh = NULL;
 203                         continue;
 204                 }
 205                 set_buffer_verified(bh);
 206
 207                 /* If the dir block has changed since the last call to
 208                  * readdir(2), then we might be pointing to an invalid
 209                  * dirent right now.  Scan from the start of the block
 210                  * to make sure. */
 211                 if (file->f_version != inode->i_version) {
 212                         for (i = 0; i < sb->s_blocksize && i < offset; ) {
 213                                 de = (struct ext4_dir_entry_2 *)
 214                                         (bh->b_data + i);
 215                                 /* It's too expensive to do a full
 216                                  * dirent test each time round this
 217                                  * loop, but we do have to test at
 218                                  * least that it is non-zero.  A
 219                                  * failure will be detected in the
 220                                  * dirent test below. */
 221                                 if (ext4_rec_len_from_disk(de->rec_len,
 222                                         sb->s_blocksize) < EXT4_DIR_REC_LEN(1))
 223                                         break;
 224                                 i += ext4_rec_len_from_disk(de->rec_len,
 225                                                             sb->s_blocksize);
 226                         }
 227                         offset = i;
 228                         ctx->pos = (ctx->pos & ~(sb->s_blocksize - 1))
 229                                 | offset;
 230                         file->f_version = inode->i_version;
 231                 }
 232
 233                 while (ctx->pos < inode->i_size
 234                        && offset < sb->s_blocksize) {
 235                         de = (struct ext4_dir_entry_2 *) (bh->b_data + offset);
 236                         if (ext4_check_dir_entry(inode, file, de, bh,
 237                                                  bh->b_data, bh->b_size,
 238                                                  offset)) {
 239                                 /*
 240                                  * On error, skip to the next block
 241                                  */
 242                                 ctx->pos = (ctx->pos |
 243                                                 (sb->s_blocksize - 1)) + 1;
 244                                 break;
 245                         }
 246                         offset += ext4_rec_len_from_disk(de->rec_len,
 247                                         sb->s_blocksize);
 248                         if (le32_to_cpu(de->inode)) {
 249                                 if (!ext4_encrypted_inode(inode)) {
 250                                         if (!dir_emit(ctx, de->name,
 251                                             de->name_len,
 252                                             le32_to_cpu(de->inode),
 253                                             get_dtype(sb, de->file_type)))
 254                                                 goto done;
 255                                 } else {
 256                                         int save_len = fname_crypto_str.len;
 257
 258                                         /* Directory is encrypted */
 259                                         err = ext4_fname_disk_to_usr(inode,
 260                                                 NULL, de, &fname_crypto_str);
 261                                         fname_crypto_str.len = save_len;
 262                                         if (err < 0)
 263                                                 goto errout;
 264                                         if (!dir_emit(ctx,
 265                                             fname_crypto_str.name, err,
 266                                             le32_to_cpu(de->inode),
 267                                             get_dtype(sb, de->file_type)))
 268                                                 goto done;
 269                                 }
 270                         }
 271                         ctx->pos += ext4_rec_len_from_disk(de->rec_len,
 272                                                 sb->s_blocksize);
 273                 }
 274                 if ((ctx->pos < inode->i_size) && !dir_relax(inode))
 275                         goto done;
 276                 brelse(bh);
 277                 bh = NULL;
 278                 offset = 0;
 279         }
 280 done:
 281         err = 0;
 282 errout:
 283 #ifdef CONFIG_EXT4_FS_ENCRYPTION
 284         ext4_fname_crypto_free_buffer(&fname_crypto_str);
 285 #endif
 286         brelse(bh);
 287         return err;
 288 }
 289
 290 static inline int is_32bit_api(void)
 291 {
 292 #ifdef CONFIG_COMPAT
 293         return in_compat_syscall();
 294 #else
 295         return (BITS_PER_LONG == 32);
 296 #endif
 297 }
 298
 299 /*
 300  * These functions convert from the major/minor hash to an f_pos
 301  * value for dx directories
 302  *
 303  * Upper layer (for example NFS) should specify FMODE_32BITHASH or
 304  * FMODE_64BITHASH explicitly. On the other hand, we allow ext4 to be mounted
 305  * directly on both 32-bit and 64-bit nodes, under such case, neither
 306  * FMODE_32BITHASH nor FMODE_64BITHASH is specified.
 307  */
 308 static inline loff_t hash2pos(struct file *filp, __u32 major, __u32 minor)
 309 {
 310         if ((filp->f_mode & FMODE_32BITHASH) ||
 311             (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
 312                 return major >> 1;
 313         else
 314                 return ((__u64)(major >> 1) << 32) | (__u64)minor;
 315 }
 316
 317 static inline __u32 pos2maj_hash(struct file *filp, loff_t pos)
 318 {
 319         if ((filp->f_mode & FMODE_32BITHASH) ||
 320             (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
 321                 return (pos << 1) & 0xffffffff;
 322         else
 323                 return ((pos >> 32) << 1) & 0xffffffff;
 324 }
 325
 326 static inline __u32 pos2min_hash(struct file *filp, loff_t pos)
 327 {
 328         if ((filp->f_mode & FMODE_32BITHASH) ||
 329             (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
 330                 return 0;
 331         else
 332                 return pos & 0xffffffff;
 333 }
 334
 335 /*
 336  * Return 32- or 64-bit end-of-file for dx directories
 337  */
 338 static inline loff_t ext4_get_htree_eof(struct file *filp)
 339 {
 340         if ((filp->f_mode & FMODE_32BITHASH) ||
 341             (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
 342                 return EXT4_HTREE_EOF_32BIT;
 343         else
 344                 return EXT4_HTREE_EOF_64BIT;
 345 }
 346
 347
 348 /*
 349  * ext4_dir_llseek() calls generic_file_llseek_size to handle htree
 350  * directories, where the "offset" is in terms of the filename hash
 351  * value instead of the byte offset.
 352  *
 353  * Because we may return a 64-bit hash that is well beyond offset limits,
 354  * we need to pass the max hash as the maximum allowable offset in
 355  * the htree directory case.
 356  *
 357  * For non-htree, ext4_llseek already chooses the proper max offset.
 358  */
 359 static loff_t ext4_dir_llseek(struct file *file, loff_t offset, int whence)
 360 {
 361         struct inode *inode = file->f_mapping->host;
 362         int dx_dir = is_dx_dir(inode);
 363         loff_t htree_max = ext4_get_htree_eof(file);
 364
 365         if (likely(dx_dir))
 366                 return generic_file_llseek_size(file, offset, whence,
 367                                                     htree_max, htree_max);
 368         else
 369                 return ext4_llseek(file, offset, whence);
 370 }
 371
 372 /*
 373  * This structure holds the nodes of the red-black tree used to store
 374  * the directory entry in hash order.
 375  */
 376 struct fname {
 377         __u32           hash;
 378         __u32           minor_hash;
 379         struct rb_node  rb_hash;
 380         struct fname    *next;
 381         __u32           inode;
 382         __u8            name_len;
 383         __u8            file_type;
 384         char            name[0];
 385 };
 386
 387 /*
 388  * This functoin implements a non-recursive way of freeing all of the
 389  * nodes in the red-black tree.
 390  */
 391 static void free_rb_tree_fname(struct rb_root *root)
 392 {
 393         struct fname *fname, *next;
 394
 395         rbtree_postorder_for_each_entry_safe(fname, next, root, rb_hash)
 396                 while (fname) {
 397                         struct fname *old = fname;
 398                         fname = fname->next;
 399                         kfree(old);
 400                 }
 401
 402         *root = RB_ROOT;
 403 }
 404
 405
 406 static struct dir_private_info *ext4_htree_create_dir_info(struct file *filp,
 407                                                            loff_t pos)
 408 {
 409         struct dir_private_info *p;
 410
 411         p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL);
 412         if (!p)
 413                 return NULL;
 414         p->curr_hash = pos2maj_hash(filp, pos);
 415         p->curr_minor_hash = pos2min_hash(filp, pos);
 416         return p;
 417 }
 418
 419 void ext4_htree_free_dir_info(struct dir_private_info *p)
 420 {
 421         free_rb_tree_fname(&p->root);
 422         kfree(p);
 423 }
 424
 425 /*
 426  * Given a directory entry, enter it into the fname rb tree.
 427  *
 428  * When filename encryption is enabled, the dirent will hold the
 429  * encrypted filename, while the htree will hold decrypted filename.
 430  * The decrypted filename is passed in via ent_name.  parameter.
 431  */
 432 int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,
 433                              __u32 minor_hash,
 434                             struct ext4_dir_entry_2 *dirent,
 435                             struct ext4_str *ent_name)
 436 {
 437         struct rb_node **p, *parent = NULL;
 438         struct fname *fname, *new_fn;
 439         struct dir_private_info *info;
 440         int len;
 441
 442         info = dir_file->private_data;
 443         p = &info->root.rb_node;
 444
 445         /* Create and allocate the fname structure */
 446         len = sizeof(struct fname) + ent_name->len + 1;
 447         new_fn = kzalloc(len, GFP_KERNEL);
 448         if (!new_fn)
 449                 return -ENOMEM;
 450         new_fn->hash = hash;
 451         new_fn->minor_hash = minor_hash;
 452         new_fn->inode = le32_to_cpu(dirent->inode);
 453         new_fn->name_len = ent_name->len;
 454         new_fn->file_type = dirent->file_type;
 455         memcpy(new_fn->name, ent_name->name, ent_name->len);
 456         new_fn->name[ent_name->len] = 0;
 457
 458         while (*p) {
 459                 parent = *p;
 460                 fname = rb_entry(parent, struct fname, rb_hash);
 461
 462                 /*
 463                  * If the hash and minor hash match up, then we put
 464                  * them on a linked list.  This rarely happens...
 465                  */
 466                 if ((new_fn->hash == fname->hash) &&
 467                     (new_fn->minor_hash == fname->minor_hash)) {
 468                         new_fn->next = fname->next;
 469                         fname->next = new_fn;
 470                         return 0;
 471                 }
 472
 473                 if (new_fn->hash < fname->hash)
 474                         p = &(*p)->rb_left;
 475                 else if (new_fn->hash > fname->hash)
 476                         p = &(*p)->rb_right;
 477                 else if (new_fn->minor_hash < fname->minor_hash)
 478                         p = &(*p)->rb_left;
 479                 else /* if (new_fn->minor_hash > fname->minor_hash) */
 480                         p = &(*p)->rb_right;
 481         }
 482
 483         rb_link_node(&new_fn->rb_hash, parent, p);
 484         rb_insert_color(&new_fn->rb_hash, &info->root);
 485         return 0;
 486 }
 487
 488
 489
 490 /*
 491  * This is a helper function for ext4_dx_readdir.  It calls filldir
 492  * for all entres on the fname linked list.  (Normally there is only
 493  * one entry on the linked list, unless there are 62 bit hash collisions.)
 494  */
 495 static int call_filldir(struct file *file, struct dir_context *ctx,
 496                         struct fname *fname)
 497 {
 498         struct dir_private_info *info = file->private_data;
 499         struct inode *inode = file_inode(file);
 500         struct super_block *sb = inode->i_sb;
 501
 502         if (!fname) {
 503                 ext4_msg(sb, KERN_ERR, "%s:%d: inode #%lu: comm %s: "
 504                          "called with null fname?!?", __func__, __LINE__,
 505                          inode->i_ino, current->comm);
 506                 return 0;
 507         }
 508         ctx->pos = hash2pos(file, fname->hash, fname->minor_hash);
 509         while (fname) {
 510                 if (!dir_emit(ctx, fname->name,
 511                                 fname->name_len,
 512                                 fname->inode,
 513                                 get_dtype(sb, fname->file_type))) {
 514                         info->extra_fname = fname;
 515                         return 1;
 516                 }
 517                 fname = fname->next;
 518         }
 519         return 0;
 520 }
 521
 522 static int ext4_dx_readdir(struct file *file, struct dir_context *ctx)
 523 {
 524         struct dir_private_info *info = file->private_data;
 525         struct inode *inode = file_inode(file);
 526         struct fname *fname;
 527         int     ret;
 528
 529         if (!info) {
 530                 info = ext4_htree_create_dir_info(file, ctx->pos);
 531                 if (!info)
 532                         return -ENOMEM;
 533                 file->private_data = info;
 534         }
 535
 536         if (ctx->pos == ext4_get_htree_eof(file))
 537                 return 0;       /* EOF */
 538
 539         /* Some one has messed with f_pos; reset the world */
 540         if (info->last_pos != ctx->pos) {
 541                 free_rb_tree_fname(&info->root);
 542                 info->curr_node = NULL;
 543                 info->extra_fname = NULL;
 544                 info->curr_hash = pos2maj_hash(file, ctx->pos);
 545                 info->curr_minor_hash = pos2min_hash(file, ctx->pos);
 546         }
 547
 548         /*
 549          * If there are any leftover names on the hash collision
 550          * chain, return them first.
 551          */
 552         if (info->extra_fname) {
 553                 if (call_filldir(file, ctx, info->extra_fname))
 554                         goto finished;
 555                 info->extra_fname = NULL;
 556                 goto next_node;
 557         } else if (!info->curr_node)
 558                 info->curr_node = rb_first(&info->root);
 559
 560         while (1) {
 561                 /*
 562                  * Fill the rbtree if we have no more entries,
 563                  * or the inode has changed since we last read in the
 564                  * cached entries.
 565                  */
 566                 if ((!info->curr_node) ||
 567                     (file->f_version != inode->i_version)) {
 568                         info->curr_node = NULL;
 569                         free_rb_tree_fname(&info->root);
 570                         file->f_version = inode->i_version;
 571                         ret = ext4_htree_fill_tree(file, info->curr_hash,
 572                                                    info->curr_minor_hash,
 573                                                    &info->next_hash);
 574                         if (ret < 0)
 575                                 return ret;
 576                         if (ret == 0) {
 577                                 ctx->pos = ext4_get_htree_eof(file);
 578                                 break;
 579                         }
 580                         info->curr_node = rb_first(&info->root);
 581                 }
 582
 583                 fname = rb_entry(info->curr_node, struct fname, rb_hash);
 584                 info->curr_hash = fname->hash;
 585                 info->curr_minor_hash = fname->minor_hash;
 586                 if (call_filldir(file, ctx, fname))
 587                         break;
 588         next_node:
 589                 info->curr_node = rb_next(info->curr_node);
 590                 if (info->curr_node) {
 591                         fname = rb_entry(info->curr_node, struct fname,
 592                                          rb_hash);
 593                         info->curr_hash = fname->hash;
 594                         info->curr_minor_hash = fname->minor_hash;
 595                 } else {
 596                         if (info->next_hash == ~0) {
 597                                 ctx->pos = ext4_get_htree_eof(file);
 598                                 break;
 599                         }
 600                         info->curr_hash = info->next_hash;
 601                         info->curr_minor_hash = 0;
 602                 }
 603         }
 604 finished:
 605         info->last_pos = ctx->pos;
 606         return 0;
 607 }
 608
 609 static int ext4_dir_open(struct inode * inode, struct file * filp)
 610 {
 611         if (ext4_encrypted_inode(inode))
 612                 return ext4_get_encryption_info(inode) ? -EACCES : 0;
 613         return 0;
 614 }
 615
 616 static int ext4_release_dir(struct inode *inode, struct file *filp)
 617 {
 618         if (filp->private_data)
 619                 ext4_htree_free_dir_info(filp->private_data);
 620
 621         return 0;
 622 }
 623
 624 int ext4_check_all_de(struct inode *dir, struct buffer_head *bh, void *buf,
 625                       int buf_size)
 626 {
 627         struct ext4_dir_entry_2 *de;
 628         int nlen, rlen;
 629         unsigned int offset = 0;
 630         char *top;
 631
 632         de = (struct ext4_dir_entry_2 *)buf;
 633         top = buf + buf_size;
 634         while ((char *) de < top) {
 635                 if (ext4_check_dir_entry(dir, NULL, de, bh,
 636                                          buf, buf_size, offset))
 637                         return -EFSCORRUPTED;
 638                 nlen = EXT4_DIR_REC_LEN(de->name_len);
 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        = 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         .open           = ext4_dir_open,
 659         .release        = ext4_release_dir,
 660 };