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 ([email protected])
   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 ([email protected]), 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 static bool is_fake_dir_entry(struct ext4_dir_entry_2 *de)
  59 {
  60         /* Check if . or .. , or skip if namelen is 0 */
  61         if ((de->name_len > 0) && (de->name_len <= 2) && (de->name[0] == '.') &&
  62             (de->name[1] == '.' || de->name[1] == '\0'))
  63                 return true;
  64         /* Check if this is a csum entry */
  65         if (de->file_type == EXT4_FT_DIR_CSUM)
  66                 return true;
  67         return false;
  68 }
  69
  70 /*
  71  * Return 0 if the directory entry is OK, and 1 if there is a problem
  72  *
  73  * Note: this is the opposite of what ext2 and ext3 historically returned...
  74  *
  75  * bh passed here can be an inode block or a dir data block, depending
  76  * on the inode inline data flag.
  77  */
  78 int __ext4_check_dir_entry(const char *function, unsigned int line,
  79                            struct inode *dir, struct file *filp,
  80                            struct ext4_dir_entry_2 *de,
  81                            struct buffer_head *bh, char *buf, int size,
  82                            unsigned int offset)
  83 {
  84         const char *error_msg = NULL;
  85         const int rlen = ext4_rec_len_from_disk(de->rec_len,
  86                                                 dir->i_sb->s_blocksize);
  87         const int next_offset = ((char *) de - buf) + rlen;
  88         bool fake = is_fake_dir_entry(de);
  89         bool has_csum = ext4_has_metadata_csum(dir->i_sb);
  90
  91         if (unlikely(rlen < ext4_dir_rec_len(1, fake ? NULL : dir)))
  92                 error_msg = "rec_len is smaller than minimal";
  93         else if (unlikely(rlen % 4 != 0))
  94                 error_msg = "rec_len % 4 != 0";
  95         else if (unlikely(rlen < ext4_dir_rec_len(de->name_len,
  96                                                         fake ? NULL : dir)))
  97                 error_msg = "rec_len is too small for name_len";
  98         else if (unlikely(next_offset > size))
  99                 error_msg = "directory entry overrun";
 100         else if (unlikely(next_offset > size - ext4_dir_rec_len(1,
 101                                                   has_csum ? NULL : dir) &&
 102                           next_offset != size))
 103                 error_msg = "directory entry too close to block end";
 104         else if (unlikely(le32_to_cpu(de->inode) >
 105                         le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count)))
 106                 error_msg = "inode out of bounds";
 107         else
 108                 return 0;
 109
 110         if (filp)
 111                 ext4_error_file(filp, function, line, bh->b_blocknr,
 112                                 "bad entry in directory: %s - offset=%u, "
 113                                 "inode=%u, rec_len=%d, size=%d fake=%d",
 114                                 error_msg, offset, le32_to_cpu(de->inode),
 115                                 rlen, size, fake);
 116         else
 117                 ext4_error_inode(dir, function, line, bh->b_blocknr,
 118                                 "bad entry in directory: %s - offset=%u, "
 119                                 "inode=%u, rec_len=%d, size=%d fake=%d",
 120                                  error_msg, offset, le32_to_cpu(de->inode),
 121                                  rlen, size, fake);
 122
 123         return 1;
 124 }
 125
 126 static int ext4_readdir(struct file *file, struct dir_context *ctx)
 127 {
 128         unsigned int offset;
 129         int i;
 130         struct ext4_dir_entry_2 *de;
 131         int err;
 132         struct inode *inode = file_inode(file);
 133         struct super_block *sb = inode->i_sb;
 134         struct buffer_head *bh = NULL;
 135         struct fscrypt_str fstr = FSTR_INIT(NULL, 0);
 136
 137         err = fscrypt_prepare_readdir(inode);
 138         if (err)
 139                 return err;
 140
 141         if (is_dx_dir(inode)) {
 142                 err = ext4_dx_readdir(file, ctx);
 143                 if (err != ERR_BAD_DX_DIR)
 144                         return err;
 145
 146                 /* Can we just clear INDEX flag to ignore htree information? */
 147                 if (!ext4_has_metadata_csum(sb)) {
 148                         /*
 149                          * We don't set the inode dirty flag since it's not
 150                          * critical that it gets flushed back to the disk.
 151                          */
 152                         ext4_clear_inode_flag(inode, EXT4_INODE_INDEX);
 153                 }
 154         }
 155
 156         if (ext4_has_inline_data(inode)) {
 157                 int has_inline_data = 1;
 158                 err = ext4_read_inline_dir(file, ctx,
 159                                            &has_inline_data);
 160                 if (has_inline_data)
 161                         return err;
 162         }
 163
 164         if (IS_ENCRYPTED(inode)) {
 165                 err = fscrypt_fname_alloc_buffer(EXT4_NAME_LEN, &fstr);
 166                 if (err < 0)
 167                         return err;
 168         }
 169
 170         while (ctx->pos < inode->i_size) {
 171                 struct ext4_map_blocks map;
 172
 173                 if (fatal_signal_pending(current)) {
 174                         err = -ERESTARTSYS;
 175                         goto errout;
 176                 }
 177                 cond_resched();
 178                 offset = ctx->pos & (sb->s_blocksize - 1);
 179                 map.m_lblk = ctx->pos >> EXT4_BLOCK_SIZE_BITS(sb);
 180                 map.m_len = 1;
 181                 err = ext4_map_blocks(NULL, inode, &map, 0);
 182                 if (err == 0) {
 183                         /* m_len should never be zero but let's avoid
 184                          * an infinite loop if it somehow is */
 185                         if (map.m_len == 0)
 186                                 map.m_len = 1;
 187                         ctx->pos += map.m_len * sb->s_blocksize;
 188                         continue;
 189                 }
 190                 if (err > 0) {
 191                         pgoff_t index = map.m_pblk >>
 192                                         (PAGE_SHIFT - inode->i_blkbits);
 193                         if (!ra_has_index(&file->f_ra, index))
 194                                 page_cache_sync_readahead(
 195                                         sb->s_bdev->bd_inode->i_mapping,
 196                                         &file->f_ra, file,
 197                                         index, 1);
 198                         file->f_ra.prev_pos = (loff_t)index << PAGE_SHIFT;
 199                         bh = ext4_bread(NULL, inode, map.m_lblk, 0);
 200                         if (IS_ERR(bh)) {
 201                                 err = PTR_ERR(bh);
 202                                 bh = NULL;
 203                                 goto errout;
 204                         }
 205                 }
 206
 207                 if (!bh) {
 208                         /* corrupt size?  Maybe no more blocks to read */
 209                         if (ctx->pos > inode->i_blocks << 9)
 210                                 break;
 211                         ctx->pos += sb->s_blocksize - offset;
 212                         continue;
 213                 }
 214
 215                 /* Check the checksum */
 216                 if (!buffer_verified(bh) &&
 217                     !ext4_dirblock_csum_verify(inode, bh)) {
 218                         EXT4_ERROR_FILE(file, 0, "directory fails checksum "
 219                                         "at offset %llu",
 220                                         (unsigned long long)ctx->pos);
 221                         ctx->pos += sb->s_blocksize - offset;
 222                         brelse(bh);
 223                         bh = NULL;
 224                         continue;
 225                 }
 226                 set_buffer_verified(bh);
 227
 228                 /* If the dir block has changed since the last call to
 229                  * readdir(2), then we might be pointing to an invalid
 230                  * dirent right now.  Scan from the start of the block
 231                  * to make sure. */
 232                 if (!inode_eq_iversion(inode, file->f_version)) {
 233                         for (i = 0; i < sb->s_blocksize && i < offset; ) {
 234                                 de = (struct ext4_dir_entry_2 *)
 235                                         (bh->b_data + i);
 236                                 /* It's too expensive to do a full
 237                                  * dirent test each time round this
 238                                  * loop, but we do have to test at
 239                                  * least that it is non-zero.  A
 240                                  * failure will be detected in the
 241                                  * dirent test below. */
 242                                 if (ext4_rec_len_from_disk(de->rec_len,
 243                                         sb->s_blocksize) < ext4_dir_rec_len(1,
 244                                                                         inode))
 245                                         break;
 246                                 i += ext4_rec_len_from_disk(de->rec_len,
 247                                                             sb->s_blocksize);
 248                         }
 249                         offset = i;
 250                         ctx->pos = (ctx->pos & ~(sb->s_blocksize - 1))
 251                                 | offset;
 252                         file->f_version = inode_query_iversion(inode);
 253                 }
 254
 255                 while (ctx->pos < inode->i_size
 256                        && offset < sb->s_blocksize) {
 257                         de = (struct ext4_dir_entry_2 *) (bh->b_data + offset);
 258                         if (ext4_check_dir_entry(inode, file, de, bh,
 259                                                  bh->b_data, bh->b_size,
 260                                                  offset)) {
 261                                 /*
 262                                  * On error, skip to the next block
 263                                  */
 264                                 ctx->pos = (ctx->pos |
 265                                                 (sb->s_blocksize - 1)) + 1;
 266                                 break;
 267                         }
 268                         offset += ext4_rec_len_from_disk(de->rec_len,
 269                                         sb->s_blocksize);
 270                         if (le32_to_cpu(de->inode)) {
 271                                 if (!IS_ENCRYPTED(inode)) {
 272                                         if (!dir_emit(ctx, de->name,
 273                                             de->name_len,
 274                                             le32_to_cpu(de->inode),
 275                                             get_dtype(sb, de->file_type)))
 276                                                 goto done;
 277                                 } else {
 278                                         int save_len = fstr.len;
 279                                         struct fscrypt_str de_name =
 280                                                         FSTR_INIT(de->name,
 281                                                                 de->name_len);
 282
 283                                         /* Directory is encrypted */
 284                                         err = fscrypt_fname_disk_to_usr(inode,
 285                                                 EXT4_DIRENT_HASH(de),
 286                                                 EXT4_DIRENT_MINOR_HASH(de),
 287                                                 &de_name, &fstr);
 288                                         de_name = fstr;
 289                                         fstr.len = save_len;
 290                                         if (err)
 291                                                 goto errout;
 292                                         if (!dir_emit(ctx,
 293                                             de_name.name, de_name.len,
 294                                             le32_to_cpu(de->inode),
 295                                             get_dtype(sb, de->file_type)))
 296                                                 goto done;
 297                                 }
 298                         }
 299                         ctx->pos += ext4_rec_len_from_disk(de->rec_len,
 300                                                 sb->s_blocksize);
 301                 }
 302                 if ((ctx->pos < inode->i_size) && !dir_relax_shared(inode))
 303                         goto done;
 304                 brelse(bh);
 305                 bh = NULL;
 306                 offset = 0;
 307         }
 308 done:
 309         err = 0;
 310 errout:
 311         fscrypt_fname_free_buffer(&fstr);
 312         brelse(bh);
 313         return err;
 314 }
 315
 316 static inline int is_32bit_api(void)
 317 {
 318 #ifdef CONFIG_COMPAT
 319         return in_compat_syscall();
 320 #else
 321         return (BITS_PER_LONG == 32);
 322 #endif
 323 }
 324
 325 /*
 326  * These functions convert from the major/minor hash to an f_pos
 327  * value for dx directories
 328  *
 329  * Upper layer (for example NFS) should specify FMODE_32BITHASH or
 330  * FMODE_64BITHASH explicitly. On the other hand, we allow ext4 to be mounted
 331  * directly on both 32-bit and 64-bit nodes, under such case, neither
 332  * FMODE_32BITHASH nor FMODE_64BITHASH is specified.
 333  */
 334 static inline loff_t hash2pos(struct file *filp, __u32 major, __u32 minor)
 335 {
 336         if ((filp->f_mode & FMODE_32BITHASH) ||
 337             (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
 338                 return major >> 1;
 339         else
 340                 return ((__u64)(major >> 1) << 32) | (__u64)minor;
 341 }
 342
 343 static inline __u32 pos2maj_hash(struct file *filp, loff_t pos)
 344 {
 345         if ((filp->f_mode & FMODE_32BITHASH) ||
 346             (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
 347                 return (pos << 1) & 0xffffffff;
 348         else
 349                 return ((pos >> 32) << 1) & 0xffffffff;
 350 }
 351
 352 static inline __u32 pos2min_hash(struct file *filp, loff_t pos)
 353 {
 354         if ((filp->f_mode & FMODE_32BITHASH) ||
 355             (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
 356                 return 0;
 357         else
 358                 return pos & 0xffffffff;
 359 }
 360
 361 /*
 362  * Return 32- or 64-bit end-of-file for dx directories
 363  */
 364 static inline loff_t ext4_get_htree_eof(struct file *filp)
 365 {
 366         if ((filp->f_mode & FMODE_32BITHASH) ||
 367             (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
 368                 return EXT4_HTREE_EOF_32BIT;
 369         else
 370                 return EXT4_HTREE_EOF_64BIT;
 371 }
 372
 373
 374 /*
 375  * ext4_dir_llseek() calls generic_file_llseek_size to handle htree
 376  * directories, where the "offset" is in terms of the filename hash
 377  * value instead of the byte offset.
 378  *
 379  * Because we may return a 64-bit hash that is well beyond offset limits,
 380  * we need to pass the max hash as the maximum allowable offset in
 381  * the htree directory case.
 382  *
 383  * For non-htree, ext4_llseek already chooses the proper max offset.
 384  */
 385 static loff_t ext4_dir_llseek(struct file *file, loff_t offset, int whence)
 386 {
 387         struct inode *inode = file->f_mapping->host;
 388         int dx_dir = is_dx_dir(inode);
 389         loff_t ret, htree_max = ext4_get_htree_eof(file);
 390
 391         if (likely(dx_dir))
 392                 ret = generic_file_llseek_size(file, offset, whence,
 393                                                     htree_max, htree_max);
 394         else
 395                 ret = ext4_llseek(file, offset, whence);
 396         file->f_version = inode_peek_iversion(inode) - 1;
 397         return ret;
 398 }
 399
 400 /*
 401  * This structure holds the nodes of the red-black tree used to store
 402  * the directory entry in hash order.
 403  */
 404 struct fname {
 405         __u32           hash;
 406         __u32           minor_hash;
 407         struct rb_node  rb_hash;
 408         struct fname    *next;
 409         __u32           inode;
 410         __u8            name_len;
 411         __u8            file_type;
 412         char            name[];
 413 };
 414
 415 /*
 416  * This functoin implements a non-recursive way of freeing all of the
 417  * nodes in the red-black tree.
 418  */
 419 static void free_rb_tree_fname(struct rb_root *root)
 420 {
 421         struct fname *fname, *next;
 422
 423         rbtree_postorder_for_each_entry_safe(fname, next, root, rb_hash)
 424                 while (fname) {
 425                         struct fname *old = fname;
 426                         fname = fname->next;
 427                         kfree(old);
 428                 }
 429
 430         *root = RB_ROOT;
 431 }
 432
 433
 434 static struct dir_private_info *ext4_htree_create_dir_info(struct file *filp,
 435                                                            loff_t pos)
 436 {
 437         struct dir_private_info *p;
 438
 439         p = kzalloc(sizeof(*p), GFP_KERNEL);
 440         if (!p)
 441                 return NULL;
 442         p->curr_hash = pos2maj_hash(filp, pos);
 443         p->curr_minor_hash = pos2min_hash(filp, pos);
 444         return p;
 445 }
 446
 447 void ext4_htree_free_dir_info(struct dir_private_info *p)
 448 {
 449         free_rb_tree_fname(&p->root);
 450         kfree(p);
 451 }
 452
 453 /*
 454  * Given a directory entry, enter it into the fname rb tree.
 455  *
 456  * When filename encryption is enabled, the dirent will hold the
 457  * encrypted filename, while the htree will hold decrypted filename.
 458  * The decrypted filename is passed in via ent_name.  parameter.
 459  */
 460 int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,
 461                              __u32 minor_hash,
 462                             struct ext4_dir_entry_2 *dirent,
 463                             struct fscrypt_str *ent_name)
 464 {
 465         struct rb_node **p, *parent = NULL;
 466         struct fname *fname, *new_fn;
 467         struct dir_private_info *info;
 468         int len;
 469
 470         info = dir_file->private_data;
 471         p = &info->root.rb_node;
 472
 473         /* Create and allocate the fname structure */
 474         len = sizeof(struct fname) + ent_name->len + 1;
 475         new_fn = kzalloc(len, GFP_KERNEL);
 476         if (!new_fn)
 477                 return -ENOMEM;
 478         new_fn->hash = hash;
 479         new_fn->minor_hash = minor_hash;
 480         new_fn->inode = le32_to_cpu(dirent->inode);
 481         new_fn->name_len = ent_name->len;
 482         new_fn->file_type = dirent->file_type;
 483         memcpy(new_fn->name, ent_name->name, ent_name->len);
 484
 485         while (*p) {
 486                 parent = *p;
 487                 fname = rb_entry(parent, struct fname, rb_hash);
 488
 489                 /*
 490                  * If the hash and minor hash match up, then we put
 491                  * them on a linked list.  This rarely happens...
 492                  */
 493                 if ((new_fn->hash == fname->hash) &&
 494                     (new_fn->minor_hash == fname->minor_hash)) {
 495                         new_fn->next = fname->next;
 496                         fname->next = new_fn;
 497                         return 0;
 498                 }
 499
 500                 if (new_fn->hash < fname->hash)
 501                         p = &(*p)->rb_left;
 502                 else if (new_fn->hash > fname->hash)
 503                         p = &(*p)->rb_right;
 504                 else if (new_fn->minor_hash < fname->minor_hash)
 505                         p = &(*p)->rb_left;
 506                 else /* if (new_fn->minor_hash > fname->minor_hash) */
 507                         p = &(*p)->rb_right;
 508         }
 509
 510         rb_link_node(&new_fn->rb_hash, parent, p);
 511         rb_insert_color(&new_fn->rb_hash, &info->root);
 512         return 0;
 513 }
 514
 515
 516
 517 /*
 518  * This is a helper function for ext4_dx_readdir.  It calls filldir
 519  * for all entres on the fname linked list.  (Normally there is only
 520  * one entry on the linked list, unless there are 62 bit hash collisions.)
 521  */
 522 static int call_filldir(struct file *file, struct dir_context *ctx,
 523                         struct fname *fname)
 524 {
 525         struct dir_private_info *info = file->private_data;
 526         struct inode *inode = file_inode(file);
 527         struct super_block *sb = inode->i_sb;
 528
 529         if (!fname) {
 530                 ext4_msg(sb, KERN_ERR, "%s:%d: inode #%lu: comm %s: "
 531                          "called with null fname?!?", __func__, __LINE__,
 532                          inode->i_ino, current->comm);
 533                 return 0;
 534         }
 535         ctx->pos = hash2pos(file, fname->hash, fname->minor_hash);
 536         while (fname) {
 537                 if (!dir_emit(ctx, fname->name,
 538                                 fname->name_len,
 539                                 fname->inode,
 540                                 get_dtype(sb, fname->file_type))) {
 541                         info->extra_fname = fname;
 542                         return 1;
 543                 }
 544                 fname = fname->next;
 545         }
 546         return 0;
 547 }
 548
 549 static int ext4_dx_readdir(struct file *file, struct dir_context *ctx)
 550 {
 551         struct dir_private_info *info = file->private_data;
 552         struct inode *inode = file_inode(file);
 553         struct fname *fname;
 554         int     ret;
 555
 556         if (!info) {
 557                 info = ext4_htree_create_dir_info(file, ctx->pos);
 558                 if (!info)
 559                         return -ENOMEM;
 560                 file->private_data = info;
 561         }
 562
 563         if (ctx->pos == ext4_get_htree_eof(file))
 564                 return 0;       /* EOF */
 565
 566         /* Some one has messed with f_pos; reset the world */
 567         if (info->last_pos != ctx->pos) {
 568                 free_rb_tree_fname(&info->root);
 569                 info->curr_node = NULL;
 570                 info->extra_fname = NULL;
 571                 info->curr_hash = pos2maj_hash(file, ctx->pos);
 572                 info->curr_minor_hash = pos2min_hash(file, ctx->pos);
 573         }
 574
 575         /*
 576          * If there are any leftover names on the hash collision
 577          * chain, return them first.
 578          */
 579         if (info->extra_fname) {
 580                 if (call_filldir(file, ctx, info->extra_fname))
 581                         goto finished;
 582                 info->extra_fname = NULL;
 583                 goto next_node;
 584         } else if (!info->curr_node)
 585                 info->curr_node = rb_first(&info->root);
 586
 587         while (1) {
 588                 /*
 589                  * Fill the rbtree if we have no more entries,
 590                  * or the inode has changed since we last read in the
 591                  * cached entries.
 592                  */
 593                 if ((!info->curr_node) ||
 594                     !inode_eq_iversion(inode, file->f_version)) {
 595                         info->curr_node = NULL;
 596                         free_rb_tree_fname(&info->root);
 597                         file->f_version = inode_query_iversion(inode);
 598                         ret = ext4_htree_fill_tree(file, info->curr_hash,
 599                                                    info->curr_minor_hash,
 600                                                    &info->next_hash);
 601                         if (ret < 0)
 602                                 return ret;
 603                         if (ret == 0) {
 604                                 ctx->pos = ext4_get_htree_eof(file);
 605                                 break;
 606                         }
 607                         info->curr_node = rb_first(&info->root);
 608                 }
 609
 610                 fname = rb_entry(info->curr_node, struct fname, rb_hash);
 611                 info->curr_hash = fname->hash;
 612                 info->curr_minor_hash = fname->minor_hash;
 613                 if (call_filldir(file, ctx, fname))
 614                         break;
 615         next_node:
 616                 info->curr_node = rb_next(info->curr_node);
 617                 if (info->curr_node) {
 618                         fname = rb_entry(info->curr_node, struct fname,
 619                                          rb_hash);
 620                         info->curr_hash = fname->hash;
 621                         info->curr_minor_hash = fname->minor_hash;
 622                 } else {
 623                         if (info->next_hash == ~0) {
 624                                 ctx->pos = ext4_get_htree_eof(file);
 625                                 break;
 626                         }
 627                         info->curr_hash = info->next_hash;
 628                         info->curr_minor_hash = 0;
 629                 }
 630         }
 631 finished:
 632         info->last_pos = ctx->pos;
 633         return 0;
 634 }
 635
 636 static int ext4_release_dir(struct inode *inode, struct file *filp)
 637 {
 638         if (filp->private_data)
 639                 ext4_htree_free_dir_info(filp->private_data);
 640
 641         return 0;
 642 }
 643
 644 int ext4_check_all_de(struct inode *dir, struct buffer_head *bh, void *buf,
 645                       int buf_size)
 646 {
 647         struct ext4_dir_entry_2 *de;
 648         int rlen;
 649         unsigned int offset = 0;
 650         char *top;
 651
 652         de = (struct ext4_dir_entry_2 *)buf;
 653         top = buf + buf_size;
 654         while ((char *) de < top) {
 655                 if (ext4_check_dir_entry(dir, NULL, de, bh,
 656                                          buf, buf_size, offset))
 657                         return -EFSCORRUPTED;
 658                 rlen = ext4_rec_len_from_disk(de->rec_len, buf_size);
 659                 de = (struct ext4_dir_entry_2 *)((char *)de + rlen);
 660                 offset += rlen;
 661         }
 662         if ((char *) de > top)
 663                 return -EFSCORRUPTED;
 664
 665         return 0;
 666 }
 667
 668 const struct file_operations ext4_dir_operations = {
 669         .llseek         = ext4_dir_llseek,
 670         .read           = generic_read_dir,
 671         .iterate_shared = ext4_readdir,
 672         .unlocked_ioctl = ext4_ioctl,
 673 #ifdef CONFIG_COMPAT
 674         .compat_ioctl   = ext4_compat_ioctl,
 675 #endif
 676         .fsync          = ext4_sync_file,
 677         .release        = ext4_release_dir,
 678 };