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         struct dir_private_info *info = file->private_data;
 137
 138         err = fscrypt_prepare_readdir(inode);
 139         if (err)
 140                 return err;
 141
 142         if (is_dx_dir(inode)) {
 143                 err = ext4_dx_readdir(file, ctx);
 144                 if (err != ERR_BAD_DX_DIR)
 145                         return err;
 146
 147                 /* Can we just clear INDEX flag to ignore htree information? */
 148                 if (!ext4_has_metadata_csum(sb)) {
 149                         /*
 150                          * We don't set the inode dirty flag since it's not
 151                          * critical that it gets flushed back to the disk.
 152                          */
 153                         ext4_clear_inode_flag(inode, EXT4_INODE_INDEX);
 154                 }
 155         }
 156
 157         if (ext4_has_inline_data(inode)) {
 158                 int has_inline_data = 1;
 159                 err = ext4_read_inline_dir(file, ctx,
 160                                            &has_inline_data);
 161                 if (has_inline_data)
 162                         return err;
 163         }
 164
 165         if (IS_ENCRYPTED(inode)) {
 166                 err = fscrypt_fname_alloc_buffer(EXT4_NAME_LEN, &fstr);
 167                 if (err < 0)
 168                         return err;
 169         }
 170
 171         while (ctx->pos < inode->i_size) {
 172                 struct ext4_map_blocks map;
 173
 174                 if (fatal_signal_pending(current)) {
 175                         err = -ERESTARTSYS;
 176                         goto errout;
 177                 }
 178                 cond_resched();
 179                 offset = ctx->pos & (sb->s_blocksize - 1);
 180                 map.m_lblk = ctx->pos >> EXT4_BLOCK_SIZE_BITS(sb);
 181                 map.m_len = 1;
 182                 err = ext4_map_blocks(NULL, inode, &map, 0);
 183                 if (err == 0) {
 184                         /* m_len should never be zero but let's avoid
 185                          * an infinite loop if it somehow is */
 186                         if (map.m_len == 0)
 187                                 map.m_len = 1;
 188                         ctx->pos += map.m_len * sb->s_blocksize;
 189                         continue;
 190                 }
 191                 if (err > 0) {
 192                         pgoff_t index = map.m_pblk >>
 193                                         (PAGE_SHIFT - inode->i_blkbits);
 194                         if (!ra_has_index(&file->f_ra, index))
 195                                 page_cache_sync_readahead(
 196                                         sb->s_bdev->bd_mapping,
 197                                         &file->f_ra, file,
 198                                         index, 1);
 199                         file->f_ra.prev_pos = (loff_t)index << PAGE_SHIFT;
 200                         bh = ext4_bread(NULL, inode, map.m_lblk, 0);
 201                         if (IS_ERR(bh)) {
 202                                 err = PTR_ERR(bh);
 203                                 bh = NULL;
 204                                 goto errout;
 205                         }
 206                 }
 207
 208                 if (!bh) {
 209                         /* corrupt size?  Maybe no more blocks to read */
 210                         if (ctx->pos > inode->i_blocks << 9)
 211                                 break;
 212                         ctx->pos += sb->s_blocksize - offset;
 213                         continue;
 214                 }
 215
 216                 /* Check the checksum */
 217                 if (!buffer_verified(bh) &&
 218                     !ext4_dirblock_csum_verify(inode, bh)) {
 219                         EXT4_ERROR_FILE(file, 0, "directory fails checksum "
 220                                         "at offset %llu",
 221                                         (unsigned long long)ctx->pos);
 222                         ctx->pos += sb->s_blocksize - offset;
 223                         brelse(bh);
 224                         bh = NULL;
 225                         continue;
 226                 }
 227                 set_buffer_verified(bh);
 228
 229                 /* If the dir block has changed since the last call to
 230                  * readdir(2), then we might be pointing to an invalid
 231                  * dirent right now.  Scan from the start of the block
 232                  * to make sure. */
 233                 if (!inode_eq_iversion(inode, info->cookie)) {
 234                         for (i = 0; i < sb->s_blocksize && i < offset; ) {
 235                                 de = (struct ext4_dir_entry_2 *)
 236                                         (bh->b_data + i);
 237                                 /* It's too expensive to do a full
 238                                  * dirent test each time round this
 239                                  * loop, but we do have to test at
 240                                  * least that it is non-zero.  A
 241                                  * failure will be detected in the
 242                                  * dirent test below. */
 243                                 if (ext4_rec_len_from_disk(de->rec_len,
 244                                         sb->s_blocksize) < ext4_dir_rec_len(1,
 245                                                                         inode))
 246                                         break;
 247                                 i += ext4_rec_len_from_disk(de->rec_len,
 248                                                             sb->s_blocksize);
 249                         }
 250                         offset = i;
 251                         ctx->pos = (ctx->pos & ~(sb->s_blocksize - 1))
 252                                 | offset;
 253                         info->cookie = inode_query_iversion(inode);
 254                 }
 255
 256                 while (ctx->pos < inode->i_size
 257                        && offset < sb->s_blocksize) {
 258                         de = (struct ext4_dir_entry_2 *) (bh->b_data + offset);
 259                         if (ext4_check_dir_entry(inode, file, de, bh,
 260                                                  bh->b_data, bh->b_size,
 261                                                  offset)) {
 262                                 /*
 263                                  * On error, skip to the next block
 264                                  */
 265                                 ctx->pos = (ctx->pos |
 266                                                 (sb->s_blocksize - 1)) + 1;
 267                                 break;
 268                         }
 269                         offset += ext4_rec_len_from_disk(de->rec_len,
 270                                         sb->s_blocksize);
 271                         if (le32_to_cpu(de->inode)) {
 272                                 if (!IS_ENCRYPTED(inode)) {
 273                                         if (!dir_emit(ctx, de->name,
 274                                             de->name_len,
 275                                             le32_to_cpu(de->inode),
 276                                             get_dtype(sb, de->file_type)))
 277                                                 goto done;
 278                                 } else {
 279                                         int save_len = fstr.len;
 280                                         struct fscrypt_str de_name =
 281                                                         FSTR_INIT(de->name,
 282                                                                 de->name_len);
 283                                         u32 hash;
 284                                         u32 minor_hash;
 285
 286                                         if (IS_CASEFOLDED(inode)) {
 287                                                 hash = EXT4_DIRENT_HASH(de);
 288                                                 minor_hash = EXT4_DIRENT_MINOR_HASH(de);
 289                                         } else {
 290                                                 hash = 0;
 291                                                 minor_hash = 0;
 292                                         }
 293
 294                                         /* Directory is encrypted */
 295                                         err = fscrypt_fname_disk_to_usr(inode,
 296                                                 hash, minor_hash, &de_name, &fstr);
 297                                         de_name = fstr;
 298                                         fstr.len = save_len;
 299                                         if (err)
 300                                                 goto errout;
 301                                         if (!dir_emit(ctx,
 302                                             de_name.name, de_name.len,
 303                                             le32_to_cpu(de->inode),
 304                                             get_dtype(sb, de->file_type)))
 305                                                 goto done;
 306                                 }
 307                         }
 308                         ctx->pos += ext4_rec_len_from_disk(de->rec_len,
 309                                                 sb->s_blocksize);
 310                 }
 311                 if ((ctx->pos < inode->i_size) && !dir_relax_shared(inode))
 312                         goto done;
 313                 brelse(bh);
 314                 bh = NULL;
 315         }
 316 done:
 317         err = 0;
 318 errout:
 319         fscrypt_fname_free_buffer(&fstr);
 320         brelse(bh);
 321         return err;
 322 }
 323
 324 static inline int is_32bit_api(void)
 325 {
 326 #ifdef CONFIG_COMPAT
 327         return in_compat_syscall();
 328 #else
 329         return (BITS_PER_LONG == 32);
 330 #endif
 331 }
 332
 333 /*
 334  * These functions convert from the major/minor hash to an f_pos
 335  * value for dx directories
 336  *
 337  * Upper layer (for example NFS) should specify FMODE_32BITHASH or
 338  * FMODE_64BITHASH explicitly. On the other hand, we allow ext4 to be mounted
 339  * directly on both 32-bit and 64-bit nodes, under such case, neither
 340  * FMODE_32BITHASH nor FMODE_64BITHASH is specified.
 341  */
 342 static inline loff_t hash2pos(struct file *filp, __u32 major, __u32 minor)
 343 {
 344         if ((filp->f_mode & FMODE_32BITHASH) ||
 345             (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
 346                 return major >> 1;
 347         else
 348                 return ((__u64)(major >> 1) << 32) | (__u64)minor;
 349 }
 350
 351 static inline __u32 pos2maj_hash(struct file *filp, loff_t pos)
 352 {
 353         if ((filp->f_mode & FMODE_32BITHASH) ||
 354             (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
 355                 return (pos << 1) & 0xffffffff;
 356         else
 357                 return ((pos >> 32) << 1) & 0xffffffff;
 358 }
 359
 360 static inline __u32 pos2min_hash(struct file *filp, loff_t pos)
 361 {
 362         if ((filp->f_mode & FMODE_32BITHASH) ||
 363             (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
 364                 return 0;
 365         else
 366                 return pos & 0xffffffff;
 367 }
 368
 369 /*
 370  * Return 32- or 64-bit end-of-file for dx directories
 371  */
 372 static inline loff_t ext4_get_htree_eof(struct file *filp)
 373 {
 374         if ((filp->f_mode & FMODE_32BITHASH) ||
 375             (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
 376                 return EXT4_HTREE_EOF_32BIT;
 377         else
 378                 return EXT4_HTREE_EOF_64BIT;
 379 }
 380
 381
 382 /*
 383  * ext4_dir_llseek() calls generic_file_llseek_size to handle htree
 384  * directories, where the "offset" is in terms of the filename hash
 385  * value instead of the byte offset.
 386  *
 387  * Because we may return a 64-bit hash that is well beyond offset limits,
 388  * we need to pass the max hash as the maximum allowable offset in
 389  * the htree directory case.
 390  *
 391  * For non-htree, ext4_llseek already chooses the proper max offset.
 392  */
 393 static loff_t ext4_dir_llseek(struct file *file, loff_t offset, int whence)
 394 {
 395         struct inode *inode = file->f_mapping->host;
 396         struct dir_private_info *info = file->private_data;
 397         int dx_dir = is_dx_dir(inode);
 398         loff_t ret, htree_max = ext4_get_htree_eof(file);
 399
 400         if (likely(dx_dir))
 401                 ret = generic_file_llseek_size(file, offset, whence,
 402                                                     htree_max, htree_max);
 403         else
 404                 ret = ext4_llseek(file, offset, whence);
 405         info->cookie = inode_peek_iversion(inode) - 1;
 406         return ret;
 407 }
 408
 409 /*
 410  * This structure holds the nodes of the red-black tree used to store
 411  * the directory entry in hash order.
 412  */
 413 struct fname {
 414         __u32           hash;
 415         __u32           minor_hash;
 416         struct rb_node  rb_hash;
 417         struct fname    *next;
 418         __u32           inode;
 419         __u8            name_len;
 420         __u8            file_type;
 421         char            name[];
 422 };
 423
 424 /*
 425  * This function implements a non-recursive way of freeing all of the
 426  * nodes in the red-black tree.
 427  */
 428 static void free_rb_tree_fname(struct rb_root *root)
 429 {
 430         struct fname *fname, *next;
 431
 432         rbtree_postorder_for_each_entry_safe(fname, next, root, rb_hash)
 433                 while (fname) {
 434                         struct fname *old = fname;
 435                         fname = fname->next;
 436                         kfree(old);
 437                 }
 438
 439         *root = RB_ROOT;
 440 }
 441
 442 static void ext4_htree_init_dir_info(struct file *filp, loff_t pos)
 443 {
 444         struct dir_private_info *p = filp->private_data;
 445
 446         if (is_dx_dir(file_inode(filp)) && !p->initialized) {
 447                 p->curr_hash = pos2maj_hash(filp, pos);
 448                 p->curr_minor_hash = pos2min_hash(filp, pos);
 449                 p->initialized = true;
 450         }
 451 }
 452
 453 void ext4_htree_free_dir_info(struct dir_private_info *p)
 454 {
 455         free_rb_tree_fname(&p->root);
 456         kfree(p);
 457 }
 458
 459 /*
 460  * Given a directory entry, enter it into the fname rb tree.
 461  *
 462  * When filename encryption is enabled, the dirent will hold the
 463  * encrypted filename, while the htree will hold decrypted filename.
 464  * The decrypted filename is passed in via ent_name.  parameter.
 465  */
 466 int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,
 467                              __u32 minor_hash,
 468                             struct ext4_dir_entry_2 *dirent,
 469                             struct fscrypt_str *ent_name)
 470 {
 471         struct rb_node **p, *parent = NULL;
 472         struct fname *fname, *new_fn;
 473         struct dir_private_info *info;
 474         int len;
 475
 476         info = dir_file->private_data;
 477         p = &info->root.rb_node;
 478
 479         /* Create and allocate the fname structure */
 480         len = sizeof(struct fname) + ent_name->len + 1;
 481         new_fn = kzalloc(len, GFP_KERNEL);
 482         if (!new_fn)
 483                 return -ENOMEM;
 484         new_fn->hash = hash;
 485         new_fn->minor_hash = minor_hash;
 486         new_fn->inode = le32_to_cpu(dirent->inode);
 487         new_fn->name_len = ent_name->len;
 488         new_fn->file_type = dirent->file_type;
 489         memcpy(new_fn->name, ent_name->name, ent_name->len);
 490
 491         while (*p) {
 492                 parent = *p;
 493                 fname = rb_entry(parent, struct fname, rb_hash);
 494
 495                 /*
 496                  * If the hash and minor hash match up, then we put
 497                  * them on a linked list.  This rarely happens...
 498                  */
 499                 if ((new_fn->hash == fname->hash) &&
 500                     (new_fn->minor_hash == fname->minor_hash)) {
 501                         new_fn->next = fname->next;
 502                         fname->next = new_fn;
 503                         return 0;
 504                 }
 505
 506                 if (new_fn->hash < fname->hash)
 507                         p = &(*p)->rb_left;
 508                 else if (new_fn->hash > fname->hash)
 509                         p = &(*p)->rb_right;
 510                 else if (new_fn->minor_hash < fname->minor_hash)
 511                         p = &(*p)->rb_left;
 512                 else /* if (new_fn->minor_hash > fname->minor_hash) */
 513                         p = &(*p)->rb_right;
 514         }
 515
 516         rb_link_node(&new_fn->rb_hash, parent, p);
 517         rb_insert_color(&new_fn->rb_hash, &info->root);
 518         return 0;
 519 }
 520
 521
 522
 523 /*
 524  * This is a helper function for ext4_dx_readdir.  It calls filldir
 525  * for all entries on the fname linked list.  (Normally there is only
 526  * one entry on the linked list, unless there are 62 bit hash collisions.)
 527  */
 528 static int call_filldir(struct file *file, struct dir_context *ctx,
 529                         struct fname *fname)
 530 {
 531         struct dir_private_info *info = file->private_data;
 532         struct inode *inode = file_inode(file);
 533         struct super_block *sb = inode->i_sb;
 534
 535         if (!fname) {
 536                 ext4_msg(sb, KERN_ERR, "%s:%d: inode #%lu: comm %s: "
 537                          "called with null fname?!?", __func__, __LINE__,
 538                          inode->i_ino, current->comm);
 539                 return 0;
 540         }
 541         ctx->pos = hash2pos(file, fname->hash, fname->minor_hash);
 542         while (fname) {
 543                 if (!dir_emit(ctx, fname->name,
 544                                 fname->name_len,
 545                                 fname->inode,
 546                                 get_dtype(sb, fname->file_type))) {
 547                         info->extra_fname = fname;
 548                         return 1;
 549                 }
 550                 fname = fname->next;
 551         }
 552         return 0;
 553 }
 554
 555 static int ext4_dx_readdir(struct file *file, struct dir_context *ctx)
 556 {
 557         struct dir_private_info *info = file->private_data;
 558         struct inode *inode = file_inode(file);
 559         struct fname *fname;
 560         int ret = 0;
 561
 562         ext4_htree_init_dir_info(file, ctx->pos);
 563
 564         if (ctx->pos == ext4_get_htree_eof(file))
 565                 return 0;       /* EOF */
 566
 567         /* Some one has messed with f_pos; reset the world */
 568         if (info->last_pos != ctx->pos) {
 569                 free_rb_tree_fname(&info->root);
 570                 info->curr_node = NULL;
 571                 info->extra_fname = NULL;
 572                 info->curr_hash = pos2maj_hash(file, ctx->pos);
 573                 info->curr_minor_hash = pos2min_hash(file, ctx->pos);
 574         }
 575
 576         /*
 577          * If there are any leftover names on the hash collision
 578          * chain, return them first.
 579          */
 580         if (info->extra_fname) {
 581                 if (call_filldir(file, ctx, info->extra_fname))
 582                         goto finished;
 583                 info->extra_fname = NULL;
 584                 goto next_node;
 585         } else if (!info->curr_node)
 586                 info->curr_node = rb_first(&info->root);
 587
 588         while (1) {
 589                 /*
 590                  * Fill the rbtree if we have no more entries,
 591                  * or the inode has changed since we last read in the
 592                  * cached entries.
 593                  */
 594                 if ((!info->curr_node) ||
 595                     !inode_eq_iversion(inode, info->cookie)) {
 596                         info->curr_node = NULL;
 597                         free_rb_tree_fname(&info->root);
 598                         info->cookie = inode_query_iversion(inode);
 599                         ret = ext4_htree_fill_tree(file, info->curr_hash,
 600                                                    info->curr_minor_hash,
 601                                                    &info->next_hash);
 602                         if (ret < 0)
 603                                 goto finished;
 604                         if (ret == 0) {
 605                                 ctx->pos = ext4_get_htree_eof(file);
 606                                 break;
 607                         }
 608                         info->curr_node = rb_first(&info->root);
 609                 }
 610
 611                 fname = rb_entry(info->curr_node, struct fname, rb_hash);
 612                 info->curr_hash = fname->hash;
 613                 info->curr_minor_hash = fname->minor_hash;
 614                 if (call_filldir(file, ctx, fname))
 615                         break;
 616         next_node:
 617                 info->curr_node = rb_next(info->curr_node);
 618                 if (info->curr_node) {
 619                         fname = rb_entry(info->curr_node, struct fname,
 620                                          rb_hash);
 621                         info->curr_hash = fname->hash;
 622                         info->curr_minor_hash = fname->minor_hash;
 623                 } else {
 624                         if (info->next_hash == ~0) {
 625                                 ctx->pos = ext4_get_htree_eof(file);
 626                                 break;
 627                         }
 628                         info->curr_hash = info->next_hash;
 629                         info->curr_minor_hash = 0;
 630                 }
 631         }
 632 finished:
 633         info->last_pos = ctx->pos;
 634         return ret < 0 ? ret : 0;
 635 }
 636
 637 static int ext4_release_dir(struct inode *inode, struct file *filp)
 638 {
 639         if (filp->private_data)
 640                 ext4_htree_free_dir_info(filp->private_data);
 641
 642         return 0;
 643 }
 644
 645 int ext4_check_all_de(struct inode *dir, struct buffer_head *bh, void *buf,
 646                       int buf_size)
 647 {
 648         struct ext4_dir_entry_2 *de;
 649         int rlen;
 650         unsigned int offset = 0;
 651         char *top;
 652
 653         de = buf;
 654         top = buf + buf_size;
 655         while ((char *) de < top) {
 656                 if (ext4_check_dir_entry(dir, NULL, de, bh,
 657                                          buf, buf_size, offset))
 658                         return -EFSCORRUPTED;
 659                 rlen = ext4_rec_len_from_disk(de->rec_len, buf_size);
 660                 de = (struct ext4_dir_entry_2 *)((char *)de + rlen);
 661                 offset += rlen;
 662         }
 663         if ((char *) de > top)
 664                 return -EFSCORRUPTED;
 665
 666         return 0;
 667 }
 668
 669 static int ext4_dir_open(struct inode *inode, struct file *file)
 670 {
 671         struct dir_private_info *info;
 672
 673         info = kzalloc(sizeof(*info), GFP_KERNEL);
 674         if (!info)
 675                 return -ENOMEM;
 676         file->private_data = info;
 677         return 0;
 678 }
 679
 680 const struct file_operations ext4_dir_operations = {
 681         .open           = ext4_dir_open,
 682         .llseek         = ext4_dir_llseek,
 683         .read           = generic_read_dir,
 684         .iterate_shared = ext4_readdir,
 685         .unlocked_ioctl = ext4_ioctl,
 686 #ifdef CONFIG_COMPAT
 687         .compat_ioctl   = ext4_compat_ioctl,
 688 #endif
 689         .fsync          = ext4_sync_file,
 690         .release        = ext4_release_dir,
 691 };