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 "ext4.h"
  29 #include "xattr.h"
  30
  31 static int ext4_dx_readdir(struct file *, struct dir_context *);
  32
  33 /**
  34  * Check if the given dir-inode refers to an htree-indexed directory
  35  * (or a directory which could potentially get converted to use htree
  36  * indexing).
  37  *
  38  * Return 1 if it is a dx dir, 0 if not
  39  */
  40 static int is_dx_dir(struct inode *inode)
  41 {
  42         struct super_block *sb = inode->i_sb;
  43
  44         if (ext4_has_feature_dir_index(inode->i_sb) &&
  45             ((ext4_test_inode_flag(inode, EXT4_INODE_INDEX)) ||
  46              ((inode->i_size >> sb->s_blocksize_bits) == 1) ||
  47              ext4_has_inline_data(inode)))
  48                 return 1;
  49
  50         return 0;
  51 }
  52
  53 /*
  54  * Return 0 if the directory entry is OK, and 1 if there is a problem
  55  *
  56  * Note: this is the opposite of what ext2 and ext3 historically returned...
  57  *
  58  * bh passed here can be an inode block or a dir data block, depending
  59  * on the inode inline data flag.
  60  */
  61 int __ext4_check_dir_entry(const char *function, unsigned int line,
  62                            struct inode *dir, struct file *filp,
  63                            struct ext4_dir_entry_2 *de,
  64                            struct buffer_head *bh, char *buf, int size,
  65                            unsigned int offset)
  66 {
  67         const char *error_msg = NULL;
  68         const int rlen = ext4_rec_len_from_disk(de->rec_len,
  69                                                 dir->i_sb->s_blocksize);
  70
  71         if (unlikely(rlen < EXT4_DIR_REC_LEN(1)))
  72                 error_msg = "rec_len is smaller than minimal";
  73         else if (unlikely(rlen % 4 != 0))
  74                 error_msg = "rec_len % 4 != 0";
  75         else if (unlikely(rlen < EXT4_DIR_REC_LEN(de->name_len)))
  76                 error_msg = "rec_len is too small for name_len";
  77         else if (unlikely(((char *) de - buf) + rlen > size))
  78                 error_msg = "directory entry across range";
  79         else if (unlikely(le32_to_cpu(de->inode) >
  80                         le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count)))
  81                 error_msg = "inode out of bounds";
  82         else
  83                 return 0;
  84
  85         if (filp)
  86                 ext4_error_file(filp, function, line, bh->b_blocknr,
  87                                 "bad entry in directory: %s - offset=%u(%u), "
  88                                 "inode=%u, rec_len=%d, name_len=%d",
  89                                 error_msg, (unsigned) (offset % size),
  90                                 offset, le32_to_cpu(de->inode),
  91                                 rlen, de->name_len);
  92         else
  93                 ext4_error_inode(dir, function, line, bh->b_blocknr,
  94                                 "bad entry in directory: %s - offset=%u(%u), "
  95                                 "inode=%u, rec_len=%d, name_len=%d",
  96                                 error_msg, (unsigned) (offset % size),
  97                                 offset, le32_to_cpu(de->inode),
  98                                 rlen, de->name_len);
  99
 100         return 1;
 101 }
 102
 103 static int ext4_readdir(struct file *file, struct dir_context *ctx)
 104 {
 105         unsigned int offset;
 106         int i;
 107         struct ext4_dir_entry_2 *de;
 108         int err;
 109         struct inode *inode = file_inode(file);
 110         struct super_block *sb = inode->i_sb;
 111         struct buffer_head *bh = NULL;
 112         int dir_has_error = 0;
 113         struct fscrypt_str fstr = FSTR_INIT(NULL, 0);
 114
 115         if (ext4_encrypted_inode(inode)) {
 116                 err = fscrypt_get_encryption_info(inode);
 117                 if (err && err != -ENOKEY)
 118                         return err;
 119         }
 120
 121         if (is_dx_dir(inode)) {
 122                 err = ext4_dx_readdir(file, ctx);
 123                 if (err != ERR_BAD_DX_DIR) {
 124                         return err;
 125                 }
 126                 /*
 127                  * We don't set the inode dirty flag since it's not
 128                  * critical that it get flushed back to the disk.
 129                  */
 130                 ext4_clear_inode_flag(file_inode(file),
 131                                       EXT4_INODE_INDEX);
 132         }
 133
 134         if (ext4_has_inline_data(inode)) {
 135                 int has_inline_data = 1;
 136                 err = ext4_read_inline_dir(file, ctx,
 137                                            &has_inline_data);
 138                 if (has_inline_data)
 139                         return err;
 140         }
 141
 142         if (ext4_encrypted_inode(inode)) {
 143                 err = fscrypt_fname_alloc_buffer(inode, EXT4_NAME_LEN, &fstr);
 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 = fstr.len;
 257                                         struct fscrypt_str de_name =
 258                                                         FSTR_INIT(de->name,
 259                                                                 de->name_len);
 260
 261                                         /* Directory is encrypted */
 262                                         err = fscrypt_fname_disk_to_usr(inode,
 263                                                 0, 0, &de_name, &fstr);
 264                                         de_name = fstr;
 265                                         fstr.len = save_len;
 266                                         if (err)
 267                                                 goto errout;
 268                                         if (!dir_emit(ctx,
 269                                             de_name.name, de_name.len,
 270                                             le32_to_cpu(de->inode),
 271                                             get_dtype(sb, de->file_type)))
 272                                                 goto done;
 273                                 }
 274                         }
 275                         ctx->pos += ext4_rec_len_from_disk(de->rec_len,
 276                                                 sb->s_blocksize);
 277                 }
 278                 if ((ctx->pos < inode->i_size) && !dir_relax_shared(inode))
 279                         goto done;
 280                 brelse(bh);
 281                 bh = NULL;
 282                 offset = 0;
 283         }
 284 done:
 285         err = 0;
 286 errout:
 287 #ifdef CONFIG_EXT4_FS_ENCRYPTION
 288         fscrypt_fname_free_buffer(&fstr);
 289 #endif
 290         brelse(bh);
 291         return err;
 292 }
 293
 294 static inline int is_32bit_api(void)
 295 {
 296 #ifdef CONFIG_COMPAT
 297         return in_compat_syscall();
 298 #else
 299         return (BITS_PER_LONG == 32);
 300 #endif
 301 }
 302
 303 /*
 304  * These functions convert from the major/minor hash to an f_pos
 305  * value for dx directories
 306  *
 307  * Upper layer (for example NFS) should specify FMODE_32BITHASH or
 308  * FMODE_64BITHASH explicitly. On the other hand, we allow ext4 to be mounted
 309  * directly on both 32-bit and 64-bit nodes, under such case, neither
 310  * FMODE_32BITHASH nor FMODE_64BITHASH is specified.
 311  */
 312 static inline loff_t hash2pos(struct file *filp, __u32 major, __u32 minor)
 313 {
 314         if ((filp->f_mode & FMODE_32BITHASH) ||
 315             (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
 316                 return major >> 1;
 317         else
 318                 return ((__u64)(major >> 1) << 32) | (__u64)minor;
 319 }
 320
 321 static inline __u32 pos2maj_hash(struct file *filp, loff_t pos)
 322 {
 323         if ((filp->f_mode & FMODE_32BITHASH) ||
 324             (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
 325                 return (pos << 1) & 0xffffffff;
 326         else
 327                 return ((pos >> 32) << 1) & 0xffffffff;
 328 }
 329
 330 static inline __u32 pos2min_hash(struct file *filp, loff_t pos)
 331 {
 332         if ((filp->f_mode & FMODE_32BITHASH) ||
 333             (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
 334                 return 0;
 335         else
 336                 return pos & 0xffffffff;
 337 }
 338
 339 /*
 340  * Return 32- or 64-bit end-of-file for dx directories
 341  */
 342 static inline loff_t ext4_get_htree_eof(struct file *filp)
 343 {
 344         if ((filp->f_mode & FMODE_32BITHASH) ||
 345             (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
 346                 return EXT4_HTREE_EOF_32BIT;
 347         else
 348                 return EXT4_HTREE_EOF_64BIT;
 349 }
 350
 351
 352 /*
 353  * ext4_dir_llseek() calls generic_file_llseek_size to handle htree
 354  * directories, where the "offset" is in terms of the filename hash
 355  * value instead of the byte offset.
 356  *
 357  * Because we may return a 64-bit hash that is well beyond offset limits,
 358  * we need to pass the max hash as the maximum allowable offset in
 359  * the htree directory case.
 360  *
 361  * For non-htree, ext4_llseek already chooses the proper max offset.
 362  */
 363 static loff_t ext4_dir_llseek(struct file *file, loff_t offset, int whence)
 364 {
 365         struct inode *inode = file->f_mapping->host;
 366         int dx_dir = is_dx_dir(inode);
 367         loff_t htree_max = ext4_get_htree_eof(file);
 368
 369         if (likely(dx_dir))
 370                 return generic_file_llseek_size(file, offset, whence,
 371                                                     htree_max, htree_max);
 372         else
 373                 return ext4_llseek(file, offset, whence);
 374 }
 375
 376 /*
 377  * This structure holds the nodes of the red-black tree used to store
 378  * the directory entry in hash order.
 379  */
 380 struct fname {
 381         __u32           hash;
 382         __u32           minor_hash;
 383         struct rb_node  rb_hash;
 384         struct fname    *next;
 385         __u32           inode;
 386         __u8            name_len;
 387         __u8            file_type;
 388         char            name[0];
 389 };
 390
 391 /*
 392  * This functoin implements a non-recursive way of freeing all of the
 393  * nodes in the red-black tree.
 394  */
 395 static void free_rb_tree_fname(struct rb_root *root)
 396 {
 397         struct fname *fname, *next;
 398
 399         rbtree_postorder_for_each_entry_safe(fname, next, root, rb_hash)
 400                 while (fname) {
 401                         struct fname *old = fname;
 402                         fname = fname->next;
 403                         kfree(old);
 404                 }
 405
 406         *root = RB_ROOT;
 407 }
 408
 409
 410 static struct dir_private_info *ext4_htree_create_dir_info(struct file *filp,
 411                                                            loff_t pos)
 412 {
 413         struct dir_private_info *p;
 414
 415         p = kzalloc(sizeof(*p), GFP_KERNEL);
 416         if (!p)
 417                 return NULL;
 418         p->curr_hash = pos2maj_hash(filp, pos);
 419         p->curr_minor_hash = pos2min_hash(filp, pos);
 420         return p;
 421 }
 422
 423 void ext4_htree_free_dir_info(struct dir_private_info *p)
 424 {
 425         free_rb_tree_fname(&p->root);
 426         kfree(p);
 427 }
 428
 429 /*
 430  * Given a directory entry, enter it into the fname rb tree.
 431  *
 432  * When filename encryption is enabled, the dirent will hold the
 433  * encrypted filename, while the htree will hold decrypted filename.
 434  * The decrypted filename is passed in via ent_name.  parameter.
 435  */
 436 int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,
 437                              __u32 minor_hash,
 438                             struct ext4_dir_entry_2 *dirent,
 439                             struct fscrypt_str *ent_name)
 440 {
 441         struct rb_node **p, *parent = NULL;
 442         struct fname *fname, *new_fn;
 443         struct dir_private_info *info;
 444         int len;
 445
 446         info = dir_file->private_data;
 447         p = &info->root.rb_node;
 448
 449         /* Create and allocate the fname structure */
 450         len = sizeof(struct fname) + ent_name->len + 1;
 451         new_fn = kzalloc(len, GFP_KERNEL);
 452         if (!new_fn)
 453                 return -ENOMEM;
 454         new_fn->hash = hash;
 455         new_fn->minor_hash = minor_hash;
 456         new_fn->inode = le32_to_cpu(dirent->inode);
 457         new_fn->name_len = ent_name->len;
 458         new_fn->file_type = dirent->file_type;
 459         memcpy(new_fn->name, ent_name->name, ent_name->len);
 460         new_fn->name[ent_name->len] = 0;
 461
 462         while (*p) {
 463                 parent = *p;
 464                 fname = rb_entry(parent, struct fname, rb_hash);
 465
 466                 /*
 467                  * If the hash and minor hash match up, then we put
 468                  * them on a linked list.  This rarely happens...
 469                  */
 470                 if ((new_fn->hash == fname->hash) &&
 471                     (new_fn->minor_hash == fname->minor_hash)) {
 472                         new_fn->next = fname->next;
 473                         fname->next = new_fn;
 474                         return 0;
 475                 }
 476
 477                 if (new_fn->hash < fname->hash)
 478                         p = &(*p)->rb_left;
 479                 else if (new_fn->hash > fname->hash)
 480                         p = &(*p)->rb_right;
 481                 else if (new_fn->minor_hash < fname->minor_hash)
 482                         p = &(*p)->rb_left;
 483                 else /* if (new_fn->minor_hash > fname->minor_hash) */
 484                         p = &(*p)->rb_right;
 485         }
 486
 487         rb_link_node(&new_fn->rb_hash, parent, p);
 488         rb_insert_color(&new_fn->rb_hash, &info->root);
 489         return 0;
 490 }
 491
 492
 493
 494 /*
 495  * This is a helper function for ext4_dx_readdir.  It calls filldir
 496  * for all entres on the fname linked list.  (Normally there is only
 497  * one entry on the linked list, unless there are 62 bit hash collisions.)
 498  */
 499 static int call_filldir(struct file *file, struct dir_context *ctx,
 500                         struct fname *fname)
 501 {
 502         struct dir_private_info *info = file->private_data;
 503         struct inode *inode = file_inode(file);
 504         struct super_block *sb = inode->i_sb;
 505
 506         if (!fname) {
 507                 ext4_msg(sb, KERN_ERR, "%s:%d: inode #%lu: comm %s: "
 508                          "called with null fname?!?", __func__, __LINE__,
 509                          inode->i_ino, current->comm);
 510                 return 0;
 511         }
 512         ctx->pos = hash2pos(file, fname->hash, fname->minor_hash);
 513         while (fname) {
 514                 if (!dir_emit(ctx, fname->name,
 515                                 fname->name_len,
 516                                 fname->inode,
 517                                 get_dtype(sb, fname->file_type))) {
 518                         info->extra_fname = fname;
 519                         return 1;
 520                 }
 521                 fname = fname->next;
 522         }
 523         return 0;
 524 }
 525
 526 static int ext4_dx_readdir(struct file *file, struct dir_context *ctx)
 527 {
 528         struct dir_private_info *info = file->private_data;
 529         struct inode *inode = file_inode(file);
 530         struct fname *fname;
 531         int     ret;
 532
 533         if (!info) {
 534                 info = ext4_htree_create_dir_info(file, ctx->pos);
 535                 if (!info)
 536                         return -ENOMEM;
 537                 file->private_data = info;
 538         }
 539
 540         if (ctx->pos == ext4_get_htree_eof(file))
 541                 return 0;       /* EOF */
 542
 543         /* Some one has messed with f_pos; reset the world */
 544         if (info->last_pos != ctx->pos) {
 545                 free_rb_tree_fname(&info->root);
 546                 info->curr_node = NULL;
 547                 info->extra_fname = NULL;
 548                 info->curr_hash = pos2maj_hash(file, ctx->pos);
 549                 info->curr_minor_hash = pos2min_hash(file, ctx->pos);
 550         }
 551
 552         /*
 553          * If there are any leftover names on the hash collision
 554          * chain, return them first.
 555          */
 556         if (info->extra_fname) {
 557                 if (call_filldir(file, ctx, info->extra_fname))
 558                         goto finished;
 559                 info->extra_fname = NULL;
 560                 goto next_node;
 561         } else if (!info->curr_node)
 562                 info->curr_node = rb_first(&info->root);
 563
 564         while (1) {
 565                 /*
 566                  * Fill the rbtree if we have no more entries,
 567                  * or the inode has changed since we last read in the
 568                  * cached entries.
 569                  */
 570                 if ((!info->curr_node) ||
 571                     (file->f_version != inode->i_version)) {
 572                         info->curr_node = NULL;
 573                         free_rb_tree_fname(&info->root);
 574                         file->f_version = inode->i_version;
 575                         ret = ext4_htree_fill_tree(file, info->curr_hash,
 576                                                    info->curr_minor_hash,
 577                                                    &info->next_hash);
 578                         if (ret < 0)
 579                                 return ret;
 580                         if (ret == 0) {
 581                                 ctx->pos = ext4_get_htree_eof(file);
 582                                 break;
 583                         }
 584                         info->curr_node = rb_first(&info->root);
 585                 }
 586
 587                 fname = rb_entry(info->curr_node, struct fname, rb_hash);
 588                 info->curr_hash = fname->hash;
 589                 info->curr_minor_hash = fname->minor_hash;
 590                 if (call_filldir(file, ctx, fname))
 591                         break;
 592         next_node:
 593                 info->curr_node = rb_next(info->curr_node);
 594                 if (info->curr_node) {
 595                         fname = rb_entry(info->curr_node, struct fname,
 596                                          rb_hash);
 597                         info->curr_hash = fname->hash;
 598                         info->curr_minor_hash = fname->minor_hash;
 599                 } else {
 600                         if (info->next_hash == ~0) {
 601                                 ctx->pos = ext4_get_htree_eof(file);
 602                                 break;
 603                         }
 604                         info->curr_hash = info->next_hash;
 605                         info->curr_minor_hash = 0;
 606                 }
 607         }
 608 finished:
 609         info->last_pos = ctx->pos;
 610         return 0;
 611 }
 612
 613 static int ext4_dir_open(struct inode * inode, struct file * filp)
 614 {
 615         if (ext4_encrypted_inode(inode))
 616                 return fscrypt_get_encryption_info(inode) ? -EACCES : 0;
 617         return 0;
 618 }
 619
 620 static int ext4_release_dir(struct inode *inode, struct file *filp)
 621 {
 622         if (filp->private_data)
 623                 ext4_htree_free_dir_info(filp->private_data);
 624
 625         return 0;
 626 }
 627
 628 int ext4_check_all_de(struct inode *dir, struct buffer_head *bh, void *buf,
 629                       int buf_size)
 630 {
 631         struct ext4_dir_entry_2 *de;
 632         int rlen;
 633         unsigned int offset = 0;
 634         char *top;
 635
 636         de = (struct ext4_dir_entry_2 *)buf;
 637         top = buf + buf_size;
 638         while ((char *) de < top) {
 639                 if (ext4_check_dir_entry(dir, NULL, de, bh,
 640                                          buf, buf_size, offset))
 641                         return -EFSCORRUPTED;
 642                 rlen = ext4_rec_len_from_disk(de->rec_len, buf_size);
 643                 de = (struct ext4_dir_entry_2 *)((char *)de + rlen);
 644                 offset += rlen;
 645         }
 646         if ((char *) de > top)
 647                 return -EFSCORRUPTED;
 648
 649         return 0;
 650 }
 651
 652 const struct file_operations ext4_dir_operations = {
 653         .llseek         = ext4_dir_llseek,
 654         .read           = generic_read_dir,
 655         .iterate_shared = ext4_readdir,
 656         .unlocked_ioctl = ext4_ioctl,
 657 #ifdef CONFIG_COMPAT
 658         .compat_ioctl   = ext4_compat_ioctl,
 659 #endif
 660         .fsync          = ext4_sync_file,
 661         .open           = ext4_dir_open,
 662         .release        = ext4_release_dir,
 663 };