linux/fs/ext3/dir.c
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   1/*
   2 *  linux/fs/ext3/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 *  ext3 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/compat.h>
  25#include "ext3.h"
  26
  27static unsigned char ext3_filetype_table[] = {
  28        DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK, DT_FIFO, DT_SOCK, DT_LNK
  29};
  30
  31static int ext3_dx_readdir(struct file * filp,
  32                           void * dirent, filldir_t filldir);
  33
  34static unsigned char get_dtype(struct super_block *sb, int filetype)
  35{
  36        if (!EXT3_HAS_INCOMPAT_FEATURE(sb, EXT3_FEATURE_INCOMPAT_FILETYPE) ||
  37            (filetype >= EXT3_FT_MAX))
  38                return DT_UNKNOWN;
  39
  40        return (ext3_filetype_table[filetype]);
  41}
  42
  43/**
  44 * Check if the given dir-inode refers to an htree-indexed directory
  45 * (or a directory which chould potentially get coverted to use htree
  46 * indexing).
  47 *
  48 * Return 1 if it is a dx dir, 0 if not
  49 */
  50static int is_dx_dir(struct inode *inode)
  51{
  52        struct super_block *sb = inode->i_sb;
  53
  54        if (EXT3_HAS_COMPAT_FEATURE(inode->i_sb,
  55                     EXT3_FEATURE_COMPAT_DIR_INDEX) &&
  56            ((EXT3_I(inode)->i_flags & EXT3_INDEX_FL) ||
  57             ((inode->i_size >> sb->s_blocksize_bits) == 1)))
  58                return 1;
  59
  60        return 0;
  61}
  62
  63int ext3_check_dir_entry (const char * function, struct inode * dir,
  64                          struct ext3_dir_entry_2 * de,
  65                          struct buffer_head * bh,
  66                          unsigned long offset)
  67{
  68        const char * error_msg = NULL;
  69        const int rlen = ext3_rec_len_from_disk(de->rec_len);
  70
  71        if (unlikely(rlen < EXT3_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 < EXT3_DIR_REC_LEN(de->name_len)))
  76                error_msg = "rec_len is too small for name_len";
  77        else if (unlikely((((char *) de - bh->b_data) + rlen > dir->i_sb->s_blocksize)))
  78                error_msg = "directory entry across blocks";
  79        else if (unlikely(le32_to_cpu(de->inode) >
  80                        le32_to_cpu(EXT3_SB(dir->i_sb)->s_es->s_inodes_count)))
  81                error_msg = "inode out of bounds";
  82
  83        if (unlikely(error_msg != NULL))
  84                ext3_error (dir->i_sb, function,
  85                        "bad entry in directory #%lu: %s - "
  86                        "offset=%lu, inode=%lu, rec_len=%d, name_len=%d",
  87                        dir->i_ino, error_msg, offset,
  88                        (unsigned long) le32_to_cpu(de->inode),
  89                        rlen, de->name_len);
  90
  91        return error_msg == NULL ? 1 : 0;
  92}
  93
  94static int ext3_readdir(struct file * filp,
  95                         void * dirent, filldir_t filldir)
  96{
  97        int error = 0;
  98        unsigned long offset;
  99        int i, stored;
 100        struct ext3_dir_entry_2 *de;
 101        int err;
 102        struct inode *inode = filp->f_path.dentry->d_inode;
 103        struct super_block *sb = inode->i_sb;
 104        int ret = 0;
 105        int dir_has_error = 0;
 106
 107        if (is_dx_dir(inode)) {
 108                err = ext3_dx_readdir(filp, dirent, filldir);
 109                if (err != ERR_BAD_DX_DIR) {
 110                        ret = err;
 111                        goto out;
 112                }
 113                /*
 114                 * We don't set the inode dirty flag since it's not
 115                 * critical that it get flushed back to the disk.
 116                 */
 117                EXT3_I(filp->f_path.dentry->d_inode)->i_flags &= ~EXT3_INDEX_FL;
 118        }
 119        stored = 0;
 120        offset = filp->f_pos & (sb->s_blocksize - 1);
 121
 122        while (!error && !stored && filp->f_pos < inode->i_size) {
 123                unsigned long blk = filp->f_pos >> EXT3_BLOCK_SIZE_BITS(sb);
 124                struct buffer_head map_bh;
 125                struct buffer_head *bh = NULL;
 126
 127                map_bh.b_state = 0;
 128                err = ext3_get_blocks_handle(NULL, inode, blk, 1, &map_bh, 0);
 129                if (err > 0) {
 130                        pgoff_t index = map_bh.b_blocknr >>
 131                                        (PAGE_CACHE_SHIFT - inode->i_blkbits);
 132                        if (!ra_has_index(&filp->f_ra, index))
 133                                page_cache_sync_readahead(
 134                                        sb->s_bdev->bd_inode->i_mapping,
 135                                        &filp->f_ra, filp,
 136                                        index, 1);
 137                        filp->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT;
 138                        bh = ext3_bread(NULL, inode, blk, 0, &err);
 139                }
 140
 141                /*
 142                 * We ignore I/O errors on directories so users have a chance
 143                 * of recovering data when there's a bad sector
 144                 */
 145                if (!bh) {
 146                        if (!dir_has_error) {
 147                                ext3_error(sb, __func__, "directory #%lu "
 148                                        "contains a hole at offset %lld",
 149                                        inode->i_ino, filp->f_pos);
 150                                dir_has_error = 1;
 151                        }
 152                        /* corrupt size?  Maybe no more blocks to read */
 153                        if (filp->f_pos > inode->i_blocks << 9)
 154                                break;
 155                        filp->f_pos += sb->s_blocksize - offset;
 156                        continue;
 157                }
 158
 159revalidate:
 160                /* If the dir block has changed since the last call to
 161                 * readdir(2), then we might be pointing to an invalid
 162                 * dirent right now.  Scan from the start of the block
 163                 * to make sure. */
 164                if (filp->f_version != inode->i_version) {
 165                        for (i = 0; i < sb->s_blocksize && i < offset; ) {
 166                                de = (struct ext3_dir_entry_2 *)
 167                                        (bh->b_data + i);
 168                                /* It's too expensive to do a full
 169                                 * dirent test each time round this
 170                                 * loop, but we do have to test at
 171                                 * least that it is non-zero.  A
 172                                 * failure will be detected in the
 173                                 * dirent test below. */
 174                                if (ext3_rec_len_from_disk(de->rec_len) <
 175                                                EXT3_DIR_REC_LEN(1))
 176                                        break;
 177                                i += ext3_rec_len_from_disk(de->rec_len);
 178                        }
 179                        offset = i;
 180                        filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1))
 181                                | offset;
 182                        filp->f_version = inode->i_version;
 183                }
 184
 185                while (!error && filp->f_pos < inode->i_size
 186                       && offset < sb->s_blocksize) {
 187                        de = (struct ext3_dir_entry_2 *) (bh->b_data + offset);
 188                        if (!ext3_check_dir_entry ("ext3_readdir", inode, de,
 189                                                   bh, offset)) {
 190                                /* On error, skip the f_pos to the
 191                                   next block. */
 192                                filp->f_pos = (filp->f_pos |
 193                                                (sb->s_blocksize - 1)) + 1;
 194                                brelse (bh);
 195                                ret = stored;
 196                                goto out;
 197                        }
 198                        offset += ext3_rec_len_from_disk(de->rec_len);
 199                        if (le32_to_cpu(de->inode)) {
 200                                /* We might block in the next section
 201                                 * if the data destination is
 202                                 * currently swapped out.  So, use a
 203                                 * version stamp to detect whether or
 204                                 * not the directory has been modified
 205                                 * during the copy operation.
 206                                 */
 207                                u64 version = filp->f_version;
 208
 209                                error = filldir(dirent, de->name,
 210                                                de->name_len,
 211                                                filp->f_pos,
 212                                                le32_to_cpu(de->inode),
 213                                                get_dtype(sb, de->file_type));
 214                                if (error)
 215                                        break;
 216                                if (version != filp->f_version)
 217                                        goto revalidate;
 218                                stored ++;
 219                        }
 220                        filp->f_pos += ext3_rec_len_from_disk(de->rec_len);
 221                }
 222                offset = 0;
 223                brelse (bh);
 224        }
 225out:
 226        return ret;
 227}
 228
 229static inline int is_32bit_api(void)
 230{
 231#ifdef CONFIG_COMPAT
 232        return is_compat_task();
 233#else
 234        return (BITS_PER_LONG == 32);
 235#endif
 236}
 237
 238/*
 239 * These functions convert from the major/minor hash to an f_pos
 240 * value for dx directories
 241 *
 242 * Upper layer (for example NFS) should specify FMODE_32BITHASH or
 243 * FMODE_64BITHASH explicitly. On the other hand, we allow ext3 to be mounted
 244 * directly on both 32-bit and 64-bit nodes, under such case, neither
 245 * FMODE_32BITHASH nor FMODE_64BITHASH is specified.
 246 */
 247static inline loff_t hash2pos(struct file *filp, __u32 major, __u32 minor)
 248{
 249        if ((filp->f_mode & FMODE_32BITHASH) ||
 250            (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
 251                return major >> 1;
 252        else
 253                return ((__u64)(major >> 1) << 32) | (__u64)minor;
 254}
 255
 256static inline __u32 pos2maj_hash(struct file *filp, loff_t pos)
 257{
 258        if ((filp->f_mode & FMODE_32BITHASH) ||
 259            (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
 260                return (pos << 1) & 0xffffffff;
 261        else
 262                return ((pos >> 32) << 1) & 0xffffffff;
 263}
 264
 265static inline __u32 pos2min_hash(struct file *filp, loff_t pos)
 266{
 267        if ((filp->f_mode & FMODE_32BITHASH) ||
 268            (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
 269                return 0;
 270        else
 271                return pos & 0xffffffff;
 272}
 273
 274/*
 275 * Return 32- or 64-bit end-of-file for dx directories
 276 */
 277static inline loff_t ext3_get_htree_eof(struct file *filp)
 278{
 279        if ((filp->f_mode & FMODE_32BITHASH) ||
 280            (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
 281                return EXT3_HTREE_EOF_32BIT;
 282        else
 283                return EXT3_HTREE_EOF_64BIT;
 284}
 285
 286
 287/*
 288 * ext3_dir_llseek() calls generic_file_llseek[_size]() to handle both
 289 * non-htree and htree directories, where the "offset" is in terms
 290 * of the filename hash value instead of the byte offset.
 291 *
 292 * Because we may return a 64-bit hash that is well beyond s_maxbytes,
 293 * we need to pass the max hash as the maximum allowable offset in
 294 * the htree directory case.
 295 *
 296 * NOTE: offsets obtained *before* ext3_set_inode_flag(dir, EXT3_INODE_INDEX)
 297 *       will be invalid once the directory was converted into a dx directory
 298 */
 299loff_t ext3_dir_llseek(struct file *file, loff_t offset, int origin)
 300{
 301        struct inode *inode = file->f_mapping->host;
 302        int dx_dir = is_dx_dir(inode);
 303        loff_t htree_max = ext3_get_htree_eof(file);
 304
 305        if (likely(dx_dir))
 306                return generic_file_llseek_size(file, offset, origin,
 307                                                htree_max, htree_max);
 308        else
 309                return generic_file_llseek(file, offset, origin);
 310}
 311
 312/*
 313 * This structure holds the nodes of the red-black tree used to store
 314 * the directory entry in hash order.
 315 */
 316struct fname {
 317        __u32           hash;
 318        __u32           minor_hash;
 319        struct rb_node  rb_hash;
 320        struct fname    *next;
 321        __u32           inode;
 322        __u8            name_len;
 323        __u8            file_type;
 324        char            name[0];
 325};
 326
 327/*
 328 * This functoin implements a non-recursive way of freeing all of the
 329 * nodes in the red-black tree.
 330 */
 331static void free_rb_tree_fname(struct rb_root *root)
 332{
 333        struct rb_node  *n = root->rb_node;
 334        struct rb_node  *parent;
 335        struct fname    *fname;
 336
 337        while (n) {
 338                /* Do the node's children first */
 339                if (n->rb_left) {
 340                        n = n->rb_left;
 341                        continue;
 342                }
 343                if (n->rb_right) {
 344                        n = n->rb_right;
 345                        continue;
 346                }
 347                /*
 348                 * The node has no children; free it, and then zero
 349                 * out parent's link to it.  Finally go to the
 350                 * beginning of the loop and try to free the parent
 351                 * node.
 352                 */
 353                parent = rb_parent(n);
 354                fname = rb_entry(n, struct fname, rb_hash);
 355                while (fname) {
 356                        struct fname * old = fname;
 357                        fname = fname->next;
 358                        kfree (old);
 359                }
 360                if (!parent)
 361                        *root = RB_ROOT;
 362                else if (parent->rb_left == n)
 363                        parent->rb_left = NULL;
 364                else if (parent->rb_right == n)
 365                        parent->rb_right = NULL;
 366                n = parent;
 367        }
 368}
 369
 370
 371static struct dir_private_info *ext3_htree_create_dir_info(struct file *filp,
 372                                                           loff_t pos)
 373{
 374        struct dir_private_info *p;
 375
 376        p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL);
 377        if (!p)
 378                return NULL;
 379        p->curr_hash = pos2maj_hash(filp, pos);
 380        p->curr_minor_hash = pos2min_hash(filp, pos);
 381        return p;
 382}
 383
 384void ext3_htree_free_dir_info(struct dir_private_info *p)
 385{
 386        free_rb_tree_fname(&p->root);
 387        kfree(p);
 388}
 389
 390/*
 391 * Given a directory entry, enter it into the fname rb tree.
 392 */
 393int ext3_htree_store_dirent(struct file *dir_file, __u32 hash,
 394                             __u32 minor_hash,
 395                             struct ext3_dir_entry_2 *dirent)
 396{
 397        struct rb_node **p, *parent = NULL;
 398        struct fname * fname, *new_fn;
 399        struct dir_private_info *info;
 400        int len;
 401
 402        info = (struct dir_private_info *) dir_file->private_data;
 403        p = &info->root.rb_node;
 404
 405        /* Create and allocate the fname structure */
 406        len = sizeof(struct fname) + dirent->name_len + 1;
 407        new_fn = kzalloc(len, GFP_KERNEL);
 408        if (!new_fn)
 409                return -ENOMEM;
 410        new_fn->hash = hash;
 411        new_fn->minor_hash = minor_hash;
 412        new_fn->inode = le32_to_cpu(dirent->inode);
 413        new_fn->name_len = dirent->name_len;
 414        new_fn->file_type = dirent->file_type;
 415        memcpy(new_fn->name, dirent->name, dirent->name_len);
 416        new_fn->name[dirent->name_len] = 0;
 417
 418        while (*p) {
 419                parent = *p;
 420                fname = rb_entry(parent, struct fname, rb_hash);
 421
 422                /*
 423                 * If the hash and minor hash match up, then we put
 424                 * them on a linked list.  This rarely happens...
 425                 */
 426                if ((new_fn->hash == fname->hash) &&
 427                    (new_fn->minor_hash == fname->minor_hash)) {
 428                        new_fn->next = fname->next;
 429                        fname->next = new_fn;
 430                        return 0;
 431                }
 432
 433                if (new_fn->hash < fname->hash)
 434                        p = &(*p)->rb_left;
 435                else if (new_fn->hash > fname->hash)
 436                        p = &(*p)->rb_right;
 437                else if (new_fn->minor_hash < fname->minor_hash)
 438                        p = &(*p)->rb_left;
 439                else /* if (new_fn->minor_hash > fname->minor_hash) */
 440                        p = &(*p)->rb_right;
 441        }
 442
 443        rb_link_node(&new_fn->rb_hash, parent, p);
 444        rb_insert_color(&new_fn->rb_hash, &info->root);
 445        return 0;
 446}
 447
 448
 449
 450/*
 451 * This is a helper function for ext3_dx_readdir.  It calls filldir
 452 * for all entres on the fname linked list.  (Normally there is only
 453 * one entry on the linked list, unless there are 62 bit hash collisions.)
 454 */
 455static int call_filldir(struct file * filp, void * dirent,
 456                        filldir_t filldir, struct fname *fname)
 457{
 458        struct dir_private_info *info = filp->private_data;
 459        loff_t  curr_pos;
 460        struct inode *inode = filp->f_path.dentry->d_inode;
 461        struct super_block * sb;
 462        int error;
 463
 464        sb = inode->i_sb;
 465
 466        if (!fname) {
 467                printk("call_filldir: called with null fname?!?\n");
 468                return 0;
 469        }
 470        curr_pos = hash2pos(filp, fname->hash, fname->minor_hash);
 471        while (fname) {
 472                error = filldir(dirent, fname->name,
 473                                fname->name_len, curr_pos,
 474                                fname->inode,
 475                                get_dtype(sb, fname->file_type));
 476                if (error) {
 477                        filp->f_pos = curr_pos;
 478                        info->extra_fname = fname;
 479                        return error;
 480                }
 481                fname = fname->next;
 482        }
 483        return 0;
 484}
 485
 486static int ext3_dx_readdir(struct file * filp,
 487                         void * dirent, filldir_t filldir)
 488{
 489        struct dir_private_info *info = filp->private_data;
 490        struct inode *inode = filp->f_path.dentry->d_inode;
 491        struct fname *fname;
 492        int     ret;
 493
 494        if (!info) {
 495                info = ext3_htree_create_dir_info(filp, filp->f_pos);
 496                if (!info)
 497                        return -ENOMEM;
 498                filp->private_data = info;
 499        }
 500
 501        if (filp->f_pos == ext3_get_htree_eof(filp))
 502                return 0;       /* EOF */
 503
 504        /* Some one has messed with f_pos; reset the world */
 505        if (info->last_pos != filp->f_pos) {
 506                free_rb_tree_fname(&info->root);
 507                info->curr_node = NULL;
 508                info->extra_fname = NULL;
 509                info->curr_hash = pos2maj_hash(filp, filp->f_pos);
 510                info->curr_minor_hash = pos2min_hash(filp, filp->f_pos);
 511        }
 512
 513        /*
 514         * If there are any leftover names on the hash collision
 515         * chain, return them first.
 516         */
 517        if (info->extra_fname) {
 518                if (call_filldir(filp, dirent, filldir, info->extra_fname))
 519                        goto finished;
 520                info->extra_fname = NULL;
 521                goto next_node;
 522        } else if (!info->curr_node)
 523                info->curr_node = rb_first(&info->root);
 524
 525        while (1) {
 526                /*
 527                 * Fill the rbtree if we have no more entries,
 528                 * or the inode has changed since we last read in the
 529                 * cached entries.
 530                 */
 531                if ((!info->curr_node) ||
 532                    (filp->f_version != inode->i_version)) {
 533                        info->curr_node = NULL;
 534                        free_rb_tree_fname(&info->root);
 535                        filp->f_version = inode->i_version;
 536                        ret = ext3_htree_fill_tree(filp, info->curr_hash,
 537                                                   info->curr_minor_hash,
 538                                                   &info->next_hash);
 539                        if (ret < 0)
 540                                return ret;
 541                        if (ret == 0) {
 542                                filp->f_pos = ext3_get_htree_eof(filp);
 543                                break;
 544                        }
 545                        info->curr_node = rb_first(&info->root);
 546                }
 547
 548                fname = rb_entry(info->curr_node, struct fname, rb_hash);
 549                info->curr_hash = fname->hash;
 550                info->curr_minor_hash = fname->minor_hash;
 551                if (call_filldir(filp, dirent, filldir, fname))
 552                        break;
 553        next_node:
 554                info->curr_node = rb_next(info->curr_node);
 555                if (info->curr_node) {
 556                        fname = rb_entry(info->curr_node, struct fname,
 557                                         rb_hash);
 558                        info->curr_hash = fname->hash;
 559                        info->curr_minor_hash = fname->minor_hash;
 560                } else {
 561                        if (info->next_hash == ~0) {
 562                                filp->f_pos = ext3_get_htree_eof(filp);
 563                                break;
 564                        }
 565                        info->curr_hash = info->next_hash;
 566                        info->curr_minor_hash = 0;
 567                }
 568        }
 569finished:
 570        info->last_pos = filp->f_pos;
 571        return 0;
 572}
 573
 574static int ext3_release_dir (struct inode * inode, struct file * filp)
 575{
 576       if (filp->private_data)
 577                ext3_htree_free_dir_info(filp->private_data);
 578
 579        return 0;
 580}
 581
 582const struct file_operations ext3_dir_operations = {
 583        .llseek         = ext3_dir_llseek,
 584        .read           = generic_read_dir,
 585        .readdir        = ext3_readdir,
 586        .unlocked_ioctl = ext3_ioctl,
 587#ifdef CONFIG_COMPAT
 588        .compat_ioctl   = ext3_compat_ioctl,
 589#endif
 590        .fsync          = ext3_sync_file,
 591        .release        = ext3_release_dir,
 592};
 593
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