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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/fs.h>
  25 #include <linux/jbd.h>
  26 #include <linux/ext3_fs.h>
  27 #include <linux/buffer_head.h>
  28 #include <linux/slab.h>
  29 #include <linux/rbtree.h>
  30
  31 static unsigned char ext3_filetype_table[] = {
  32         DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK, DT_FIFO, DT_SOCK, DT_LNK
  33 };
  34
  35 static int ext3_readdir(struct file *, void *, filldir_t);
  36 static int ext3_dx_readdir(struct file * filp,
  37                            void * dirent, filldir_t filldir);
  38 static int ext3_release_dir (struct inode * inode,
  39                                 struct file * filp);
  40
  41 const struct file_operations ext3_dir_operations = {
  42         .llseek         = generic_file_llseek,
  43         .read           = generic_read_dir,
  44         .readdir        = ext3_readdir,         /* we take BKL. needed?*/
  45         .unlocked_ioctl = ext3_ioctl,
  46 #ifdef CONFIG_COMPAT
  47         .compat_ioctl   = ext3_compat_ioctl,
  48 #endif
  49         .fsync          = ext3_sync_file,       /* BKL held */
  50         .release        = ext3_release_dir,
  51 };
  52
  53
  54 static unsigned char get_dtype(struct super_block *sb, int filetype)
  55 {
  56         if (!EXT3_HAS_INCOMPAT_FEATURE(sb, EXT3_FEATURE_INCOMPAT_FILETYPE) ||
  57             (filetype >= EXT3_FT_MAX))
  58                 return DT_UNKNOWN;
  59
  60         return (ext3_filetype_table[filetype]);
  61 }
  62
  63
  64 int ext3_check_dir_entry (const char * function, struct inode * dir,
  65                           struct ext3_dir_entry_2 * de,
  66                           struct buffer_head * bh,
  67                           unsigned long offset)
  68 {
  69         const char * error_msg = NULL;
  70         const int rlen = ext3_rec_len_from_disk(de->rec_len);
  71
  72         if (rlen < EXT3_DIR_REC_LEN(1))
  73                 error_msg = "rec_len is smaller than minimal";
  74         else if (rlen % 4 != 0)
  75                 error_msg = "rec_len % 4 != 0";
  76         else if (rlen < EXT3_DIR_REC_LEN(de->name_len))
  77                 error_msg = "rec_len is too small for name_len";
  78         else if (((char *) de - bh->b_data) + rlen > dir->i_sb->s_blocksize)
  79                 error_msg = "directory entry across blocks";
  80         else if (le32_to_cpu(de->inode) >
  81                         le32_to_cpu(EXT3_SB(dir->i_sb)->s_es->s_inodes_count))
  82                 error_msg = "inode out of bounds";
  83
  84         if (error_msg != NULL)
  85                 ext3_error (dir->i_sb, function,
  86                         "bad entry in directory #%lu: %s - "
  87                         "offset=%lu, inode=%lu, rec_len=%d, name_len=%d",
  88                         dir->i_ino, error_msg, offset,
  89                         (unsigned long) le32_to_cpu(de->inode),
  90                         rlen, de->name_len);
  91         return error_msg == NULL ? 1 : 0;
  92 }
  93
  94 static 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         struct super_block *sb;
 102         int err;
 103         struct inode *inode = filp->f_path.dentry->d_inode;
 104         int ret = 0;
 105         int dir_has_error = 0;
 106
 107         sb = inode->i_sb;
 108
 109         if (EXT3_HAS_COMPAT_FEATURE(inode->i_sb,
 110                                     EXT3_FEATURE_COMPAT_DIR_INDEX) &&
 111             ((EXT3_I(inode)->i_flags & EXT3_INDEX_FL) ||
 112              ((inode->i_size >> sb->s_blocksize_bits) == 1))) {
 113                 err = ext3_dx_readdir(filp, dirent, filldir);
 114                 if (err != ERR_BAD_DX_DIR) {
 115                         ret = err;
 116                         goto out;
 117                 }
 118                 /*
 119                  * We don't set the inode dirty flag since it's not
 120                  * critical that it get flushed back to the disk.
 121                  */
 122                 EXT3_I(filp->f_path.dentry->d_inode)->i_flags &= ~EXT3_INDEX_FL;
 123         }
 124         stored = 0;
 125         offset = filp->f_pos & (sb->s_blocksize - 1);
 126
 127         while (!error && !stored && filp->f_pos < inode->i_size) {
 128                 unsigned long blk = filp->f_pos >> EXT3_BLOCK_SIZE_BITS(sb);
 129                 struct buffer_head map_bh;
 130                 struct buffer_head *bh = NULL;
 131
 132                 map_bh.b_state = 0;
 133                 err = ext3_get_blocks_handle(NULL, inode, blk, 1, &map_bh, 0);
 134                 if (err > 0) {
 135                         pgoff_t index = map_bh.b_blocknr >>
 136                                         (PAGE_CACHE_SHIFT - inode->i_blkbits);
 137                         if (!ra_has_index(&filp->f_ra, index))
 138                                 page_cache_sync_readahead(
 139                                         sb->s_bdev->bd_inode->i_mapping,
 140                                         &filp->f_ra, filp,
 141                                         index, 1);
 142                         filp->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT;
 143                         bh = ext3_bread(NULL, inode, blk, 0, &err);
 144                 }
 145
 146                 /*
 147                  * We ignore I/O errors on directories so users have a chance
 148                  * of recovering data when there's a bad sector
 149                  */
 150                 if (!bh) {
 151                         if (!dir_has_error) {
 152                                 ext3_error(sb, __func__, "directory #%lu "
 153                                         "contains a hole at offset %lld",
 154                                         inode->i_ino, filp->f_pos);
 155                                 dir_has_error = 1;
 156                         }
 157                         /* corrupt size?  Maybe no more blocks to read */
 158                         if (filp->f_pos > inode->i_blocks << 9)
 159                                 break;
 160                         filp->f_pos += sb->s_blocksize - offset;
 161                         continue;
 162                 }
 163
 164 revalidate:
 165                 /* If the dir block has changed since the last call to
 166                  * readdir(2), then we might be pointing to an invalid
 167                  * dirent right now.  Scan from the start of the block
 168                  * to make sure. */
 169                 if (filp->f_version != inode->i_version) {
 170                         for (i = 0; i < sb->s_blocksize && i < offset; ) {
 171                                 de = (struct ext3_dir_entry_2 *)
 172                                         (bh->b_data + i);
 173                                 /* It's too expensive to do a full
 174                                  * dirent test each time round this
 175                                  * loop, but we do have to test at
 176                                  * least that it is non-zero.  A
 177                                  * failure will be detected in the
 178                                  * dirent test below. */
 179                                 if (ext3_rec_len_from_disk(de->rec_len) <
 180                                                 EXT3_DIR_REC_LEN(1))
 181                                         break;
 182                                 i += ext3_rec_len_from_disk(de->rec_len);
 183                         }
 184                         offset = i;
 185                         filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1))
 186                                 | offset;
 187                         filp->f_version = inode->i_version;
 188                 }
 189
 190                 while (!error && filp->f_pos < inode->i_size
 191                        && offset < sb->s_blocksize) {
 192                         de = (struct ext3_dir_entry_2 *) (bh->b_data + offset);
 193                         if (!ext3_check_dir_entry ("ext3_readdir", inode, de,
 194                                                    bh, offset)) {
 195                                 /* On error, skip the f_pos to the
 196                                    next block. */
 197                                 filp->f_pos = (filp->f_pos |
 198                                                 (sb->s_blocksize - 1)) + 1;
 199                                 brelse (bh);
 200                                 ret = stored;
 201                                 goto out;
 202                         }
 203                         offset += ext3_rec_len_from_disk(de->rec_len);
 204                         if (le32_to_cpu(de->inode)) {
 205                                 /* We might block in the next section
 206                                  * if the data destination is
 207                                  * currently swapped out.  So, use a
 208                                  * version stamp to detect whether or
 209                                  * not the directory has been modified
 210                                  * during the copy operation.
 211                                  */
 212                                 u64 version = filp->f_version;
 213
 214                                 error = filldir(dirent, de->name,
 215                                                 de->name_len,
 216                                                 filp->f_pos,
 217                                                 le32_to_cpu(de->inode),
 218                                                 get_dtype(sb, de->file_type));
 219                                 if (error)
 220                                         break;
 221                                 if (version != filp->f_version)
 222                                         goto revalidate;
 223                                 stored ++;
 224                         }
 225                         filp->f_pos += ext3_rec_len_from_disk(de->rec_len);
 226                 }
 227                 offset = 0;
 228                 brelse (bh);
 229         }
 230 out:
 231         return ret;
 232 }
 233
 234 /*
 235  * These functions convert from the major/minor hash to an f_pos
 236  * value.
 237  *
 238  * Currently we only use major hash numer.  This is unfortunate, but
 239  * on 32-bit machines, the same VFS interface is used for lseek and
 240  * llseek, so if we use the 64 bit offset, then the 32-bit versions of
 241  * lseek/telldir/seekdir will blow out spectacularly, and from within
 242  * the ext2 low-level routine, we don't know if we're being called by
 243  * a 64-bit version of the system call or the 32-bit version of the
 244  * system call.  Worse yet, NFSv2 only allows for a 32-bit readdir
 245  * cookie.  Sigh.
 246  */
 247 #define hash2pos(major, minor)  (major >> 1)
 248 #define pos2maj_hash(pos)       ((pos << 1) & 0xffffffff)
 249 #define pos2min_hash(pos)       (0)
 250
 251 /*
 252  * This structure holds the nodes of the red-black tree used to store
 253  * the directory entry in hash order.
 254  */
 255 struct fname {
 256         __u32           hash;
 257         __u32           minor_hash;
 258         struct rb_node  rb_hash;
 259         struct fname    *next;
 260         __u32           inode;
 261         __u8            name_len;
 262         __u8            file_type;
 263         char            name[0];
 264 };
 265
 266 /*
 267  * This functoin implements a non-recursive way of freeing all of the
 268  * nodes in the red-black tree.
 269  */
 270 static void free_rb_tree_fname(struct rb_root *root)
 271 {
 272         struct rb_node  *n = root->rb_node;
 273         struct rb_node  *parent;
 274         struct fname    *fname;
 275
 276         while (n) {
 277                 /* Do the node's children first */
 278                 if (n->rb_left) {
 279                         n = n->rb_left;
 280                         continue;
 281                 }
 282                 if (n->rb_right) {
 283                         n = n->rb_right;
 284                         continue;
 285                 }
 286                 /*
 287                  * The node has no children; free it, and then zero
 288                  * out parent's link to it.  Finally go to the
 289                  * beginning of the loop and try to free the parent
 290                  * node.
 291                  */
 292                 parent = rb_parent(n);
 293                 fname = rb_entry(n, struct fname, rb_hash);
 294                 while (fname) {
 295                         struct fname * old = fname;
 296                         fname = fname->next;
 297                         kfree (old);
 298                 }
 299                 if (!parent)
 300                         root->rb_node = NULL;
 301                 else if (parent->rb_left == n)
 302                         parent->rb_left = NULL;
 303                 else if (parent->rb_right == n)
 304                         parent->rb_right = NULL;
 305                 n = parent;
 306         }
 307 }
 308
 309
 310 static struct dir_private_info *ext3_htree_create_dir_info(loff_t pos)
 311 {
 312         struct dir_private_info *p;
 313
 314         p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL);
 315         if (!p)
 316                 return NULL;
 317         p->curr_hash = pos2maj_hash(pos);
 318         p->curr_minor_hash = pos2min_hash(pos);
 319         return p;
 320 }
 321
 322 void ext3_htree_free_dir_info(struct dir_private_info *p)
 323 {
 324         free_rb_tree_fname(&p->root);
 325         kfree(p);
 326 }
 327
 328 /*
 329  * Given a directory entry, enter it into the fname rb tree.
 330  */
 331 int ext3_htree_store_dirent(struct file *dir_file, __u32 hash,
 332                              __u32 minor_hash,
 333                              struct ext3_dir_entry_2 *dirent)
 334 {
 335         struct rb_node **p, *parent = NULL;
 336         struct fname * fname, *new_fn;
 337         struct dir_private_info *info;
 338         int len;
 339
 340         info = (struct dir_private_info *) dir_file->private_data;
 341         p = &info->root.rb_node;
 342
 343         /* Create and allocate the fname structure */
 344         len = sizeof(struct fname) + dirent->name_len + 1;
 345         new_fn = kzalloc(len, GFP_KERNEL);
 346         if (!new_fn)
 347                 return -ENOMEM;
 348         new_fn->hash = hash;
 349         new_fn->minor_hash = minor_hash;
 350         new_fn->inode = le32_to_cpu(dirent->inode);
 351         new_fn->name_len = dirent->name_len;
 352         new_fn->file_type = dirent->file_type;
 353         memcpy(new_fn->name, dirent->name, dirent->name_len);
 354         new_fn->name[dirent->name_len] = 0;
 355
 356         while (*p) {
 357                 parent = *p;
 358                 fname = rb_entry(parent, struct fname, rb_hash);
 359
 360                 /*
 361                  * If the hash and minor hash match up, then we put
 362                  * them on a linked list.  This rarely happens...
 363                  */
 364                 if ((new_fn->hash == fname->hash) &&
 365                     (new_fn->minor_hash == fname->minor_hash)) {
 366                         new_fn->next = fname->next;
 367                         fname->next = new_fn;
 368                         return 0;
 369                 }
 370
 371                 if (new_fn->hash < fname->hash)
 372                         p = &(*p)->rb_left;
 373                 else if (new_fn->hash > fname->hash)
 374                         p = &(*p)->rb_right;
 375                 else if (new_fn->minor_hash < fname->minor_hash)
 376                         p = &(*p)->rb_left;
 377                 else /* if (new_fn->minor_hash > fname->minor_hash) */
 378                         p = &(*p)->rb_right;
 379         }
 380
 381         rb_link_node(&new_fn->rb_hash, parent, p);
 382         rb_insert_color(&new_fn->rb_hash, &info->root);
 383         return 0;
 384 }
 385
 386
 387
 388 /*
 389  * This is a helper function for ext3_dx_readdir.  It calls filldir
 390  * for all entres on the fname linked list.  (Normally there is only
 391  * one entry on the linked list, unless there are 62 bit hash collisions.)
 392  */
 393 static int call_filldir(struct file * filp, void * dirent,
 394                         filldir_t filldir, struct fname *fname)
 395 {
 396         struct dir_private_info *info = filp->private_data;
 397         loff_t  curr_pos;
 398         struct inode *inode = filp->f_path.dentry->d_inode;
 399         struct super_block * sb;
 400         int error;
 401
 402         sb = inode->i_sb;
 403
 404         if (!fname) {
 405                 printk("call_filldir: called with null fname?!?\n");
 406                 return 0;
 407         }
 408         curr_pos = hash2pos(fname->hash, fname->minor_hash);
 409         while (fname) {
 410                 error = filldir(dirent, fname->name,
 411                                 fname->name_len, curr_pos,
 412                                 fname->inode,
 413                                 get_dtype(sb, fname->file_type));
 414                 if (error) {
 415                         filp->f_pos = curr_pos;
 416                         info->extra_fname = fname;
 417                         return error;
 418                 }
 419                 fname = fname->next;
 420         }
 421         return 0;
 422 }
 423
 424 static int ext3_dx_readdir(struct file * filp,
 425                          void * dirent, filldir_t filldir)
 426 {
 427         struct dir_private_info *info = filp->private_data;
 428         struct inode *inode = filp->f_path.dentry->d_inode;
 429         struct fname *fname;
 430         int     ret;
 431
 432         if (!info) {
 433                 info = ext3_htree_create_dir_info(filp->f_pos);
 434                 if (!info)
 435                         return -ENOMEM;
 436                 filp->private_data = info;
 437         }
 438
 439         if (filp->f_pos == EXT3_HTREE_EOF)
 440                 return 0;       /* EOF */
 441
 442         /* Some one has messed with f_pos; reset the world */
 443         if (info->last_pos != filp->f_pos) {
 444                 free_rb_tree_fname(&info->root);
 445                 info->curr_node = NULL;
 446                 info->extra_fname = NULL;
 447                 info->curr_hash = pos2maj_hash(filp->f_pos);
 448                 info->curr_minor_hash = pos2min_hash(filp->f_pos);
 449         }
 450
 451         /*
 452          * If there are any leftover names on the hash collision
 453          * chain, return them first.
 454          */
 455         if (info->extra_fname) {
 456                 if (call_filldir(filp, dirent, filldir, info->extra_fname))
 457                         goto finished;
 458                 info->extra_fname = NULL;
 459                 goto next_node;
 460         } else if (!info->curr_node)
 461                 info->curr_node = rb_first(&info->root);
 462
 463         while (1) {
 464                 /*
 465                  * Fill the rbtree if we have no more entries,
 466                  * or the inode has changed since we last read in the
 467                  * cached entries.
 468                  */
 469                 if ((!info->curr_node) ||
 470                     (filp->f_version != inode->i_version)) {
 471                         info->curr_node = NULL;
 472                         free_rb_tree_fname(&info->root);
 473                         filp->f_version = inode->i_version;
 474                         ret = ext3_htree_fill_tree(filp, info->curr_hash,
 475                                                    info->curr_minor_hash,
 476                                                    &info->next_hash);
 477                         if (ret < 0)
 478                                 return ret;
 479                         if (ret == 0) {
 480                                 filp->f_pos = EXT3_HTREE_EOF;
 481                                 break;
 482                         }
 483                         info->curr_node = rb_first(&info->root);
 484                 }
 485
 486                 fname = rb_entry(info->curr_node, struct fname, rb_hash);
 487                 info->curr_hash = fname->hash;
 488                 info->curr_minor_hash = fname->minor_hash;
 489                 if (call_filldir(filp, dirent, filldir, fname))
 490                         break;
 491         next_node:
 492                 info->curr_node = rb_next(info->curr_node);
 493                 if (info->curr_node) {
 494                         fname = rb_entry(info->curr_node, struct fname,
 495                                          rb_hash);
 496                         info->curr_hash = fname->hash;
 497                         info->curr_minor_hash = fname->minor_hash;
 498                 } else {
 499                         if (info->next_hash == ~0) {
 500                                 filp->f_pos = EXT3_HTREE_EOF;
 501                                 break;
 502                         }
 503                         info->curr_hash = info->next_hash;
 504                         info->curr_minor_hash = 0;
 505                 }
 506         }
 507 finished:
 508         info->last_pos = filp->f_pos;
 509         return 0;
 510 }
 511
 512 static int ext3_release_dir (struct inode * inode, struct file * filp)
 513 {
 514        if (filp->private_data)
 515                 ext3_htree_free_dir_info(filp->private_data);
 516
 517         return 0;
 518 }