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   1 /*
   2  *  linux/fs/ext4/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  *  ext4 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/jbd2.h>
  26 #include <linux/ext4_fs.h>
  27 #include <linux/buffer_head.h>
  28 #include <linux/slab.h>
  29 #include <linux/rbtree.h>
  30
  31 static unsigned char ext4_filetype_table[] = {
  32         DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK, DT_FIFO, DT_SOCK, DT_LNK
  33 };
  34
  35 static int ext4_readdir(struct file *, void *, filldir_t);
  36 static int ext4_dx_readdir(struct file * filp,
  37                            void * dirent, filldir_t filldir);
  38 static int ext4_release_dir (struct inode * inode,
  39                                 struct file * filp);
  40
  41 const struct file_operations ext4_dir_operations = {
  42         .llseek         = generic_file_llseek,
  43         .read           = generic_read_dir,
  44         .readdir        = ext4_readdir,         /* we take BKL. needed?*/
  45         .ioctl          = ext4_ioctl,           /* BKL held */
  46 #ifdef CONFIG_COMPAT
  47         .compat_ioctl   = ext4_compat_ioctl,
  48 #endif
  49         .fsync          = ext4_sync_file,       /* BKL held */
  50 #ifdef CONFIG_EXT4_INDEX
  51         .release        = ext4_release_dir,
  52 #endif
  53 };
  54
  55
  56 static unsigned char get_dtype(struct super_block *sb, int filetype)
  57 {
  58         if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FILETYPE) ||
  59             (filetype >= EXT4_FT_MAX))
  60                 return DT_UNKNOWN;
  61
  62         return (ext4_filetype_table[filetype]);
  63 }
  64
  65
  66 int ext4_check_dir_entry (const char * function, struct inode * dir,
  67                           struct ext4_dir_entry_2 * de,
  68                           struct buffer_head * bh,
  69                           unsigned long offset)
  70 {
  71         const char * error_msg = NULL;
  72         const int rlen = le16_to_cpu(de->rec_len);
  73
  74         if (rlen < EXT4_DIR_REC_LEN(1))
  75                 error_msg = "rec_len is smaller than minimal";
  76         else if (rlen % 4 != 0)
  77                 error_msg = "rec_len % 4 != 0";
  78         else if (rlen < EXT4_DIR_REC_LEN(de->name_len))
  79                 error_msg = "rec_len is too small for name_len";
  80         else if (((char *) de - bh->b_data) + rlen > dir->i_sb->s_blocksize)
  81                 error_msg = "directory entry across blocks";
  82         else if (le32_to_cpu(de->inode) >
  83                         le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count))
  84                 error_msg = "inode out of bounds";
  85
  86         if (error_msg != NULL)
  87                 ext4_error (dir->i_sb, function,
  88                         "bad entry in directory #%lu: %s - "
  89                         "offset=%lu, inode=%lu, rec_len=%d, name_len=%d",
  90                         dir->i_ino, error_msg, offset,
  91                         (unsigned long) le32_to_cpu(de->inode),
  92                         rlen, de->name_len);
  93         return error_msg == NULL ? 1 : 0;
  94 }
  95
  96 static int ext4_readdir(struct file * filp,
  97                          void * dirent, filldir_t filldir)
  98 {
  99         int error = 0;
 100         unsigned long offset;
 101         int i, stored;
 102         struct ext4_dir_entry_2 *de;
 103         struct super_block *sb;
 104         int err;
 105         struct inode *inode = filp->f_path.dentry->d_inode;
 106         int ret = 0;
 107
 108         sb = inode->i_sb;
 109
 110 #ifdef CONFIG_EXT4_INDEX
 111         if (EXT4_HAS_COMPAT_FEATURE(inode->i_sb,
 112                                     EXT4_FEATURE_COMPAT_DIR_INDEX) &&
 113             ((EXT4_I(inode)->i_flags & EXT4_INDEX_FL) ||
 114              ((inode->i_size >> sb->s_blocksize_bits) == 1))) {
 115                 err = ext4_dx_readdir(filp, dirent, filldir);
 116                 if (err != ERR_BAD_DX_DIR) {
 117                         ret = err;
 118                         goto out;
 119                 }
 120                 /*
 121                  * We don't set the inode dirty flag since it's not
 122                  * critical that it get flushed back to the disk.
 123                  */
 124                 EXT4_I(filp->f_path.dentry->d_inode)->i_flags &= ~EXT4_INDEX_FL;
 125         }
 126 #endif
 127         stored = 0;
 128         offset = filp->f_pos & (sb->s_blocksize - 1);
 129
 130         while (!error && !stored && filp->f_pos < inode->i_size) {
 131                 unsigned long blk = filp->f_pos >> EXT4_BLOCK_SIZE_BITS(sb);
 132                 struct buffer_head map_bh;
 133                 struct buffer_head *bh = NULL;
 134
 135                 map_bh.b_state = 0;
 136                 err = ext4_get_blocks_wrap(NULL, inode, blk, 1, &map_bh, 0, 0);
 137                 if (err > 0) {
 138                         page_cache_readahead(sb->s_bdev->bd_inode->i_mapping,
 139                                 &filp->f_ra,
 140                                 filp,
 141                                 map_bh.b_blocknr >>
 142                                         (PAGE_CACHE_SHIFT - inode->i_blkbits),
 143                                 1);
 144                         bh = ext4_bread(NULL, inode, blk, 0, &err);
 145                 }
 146
 147                 /*
 148                  * We ignore I/O errors on directories so users have a chance
 149                  * of recovering data when there's a bad sector
 150                  */
 151                 if (!bh) {
 152                         ext4_error (sb, "ext4_readdir",
 153                                 "directory #%lu contains a hole at offset %lu",
 154                                 inode->i_ino, (unsigned long)filp->f_pos);
 155                         /* corrupt size?  Maybe no more blocks to read */
 156                         if (filp->f_pos > inode->i_blocks << 9)
 157                                 break;
 158                         filp->f_pos += sb->s_blocksize - offset;
 159                         continue;
 160                 }
 161
 162 revalidate:
 163                 /* If the dir block has changed since the last call to
 164                  * readdir(2), then we might be pointing to an invalid
 165                  * dirent right now.  Scan from the start of the block
 166                  * to make sure. */
 167                 if (filp->f_version != inode->i_version) {
 168                         for (i = 0; i < sb->s_blocksize && i < offset; ) {
 169                                 de = (struct ext4_dir_entry_2 *)
 170                                         (bh->b_data + i);
 171                                 /* It's too expensive to do a full
 172                                  * dirent test each time round this
 173                                  * loop, but we do have to test at
 174                                  * least that it is non-zero.  A
 175                                  * failure will be detected in the
 176                                  * dirent test below. */
 177                                 if (le16_to_cpu(de->rec_len) <
 178                                                 EXT4_DIR_REC_LEN(1))
 179                                         break;
 180                                 i += le16_to_cpu(de->rec_len);
 181                         }
 182                         offset = i;
 183                         filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1))
 184                                 | offset;
 185                         filp->f_version = inode->i_version;
 186                 }
 187
 188                 while (!error && filp->f_pos < inode->i_size
 189                        && offset < sb->s_blocksize) {
 190                         de = (struct ext4_dir_entry_2 *) (bh->b_data + offset);
 191                         if (!ext4_check_dir_entry ("ext4_readdir", inode, de,
 192                                                    bh, offset)) {
 193                                 /*
 194                                  * On error, skip the f_pos to the next block
 195                                  */
 196                                 filp->f_pos = (filp->f_pos |
 197                                                 (sb->s_blocksize - 1)) + 1;
 198                                 brelse (bh);
 199                                 ret = stored;
 200                                 goto out;
 201                         }
 202                         offset += le16_to_cpu(de->rec_len);
 203                         if (le32_to_cpu(de->inode)) {
 204                                 /* We might block in the next section
 205                                  * if the data destination is
 206                                  * currently swapped out.  So, use a
 207                                  * version stamp to detect whether or
 208                                  * not the directory has been modified
 209                                  * during the copy operation.
 210                                  */
 211                                 unsigned long version = filp->f_version;
 212
 213                                 error = filldir(dirent, de->name,
 214                                                 de->name_len,
 215                                                 filp->f_pos,
 216                                                 le32_to_cpu(de->inode),
 217                                                 get_dtype(sb, de->file_type));
 218                                 if (error)
 219                                         break;
 220                                 if (version != filp->f_version)
 221                                         goto revalidate;
 222                                 stored ++;
 223                         }
 224                         filp->f_pos += le16_to_cpu(de->rec_len);
 225                 }
 226                 offset = 0;
 227                 brelse (bh);
 228         }
 229 out:
 230         return ret;
 231 }
 232
 233 #ifdef CONFIG_EXT4_INDEX
 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         root->rb_node = NULL;
 308 }
 309
 310
 311 static struct dir_private_info *create_dir_info(loff_t pos)
 312 {
 313         struct dir_private_info *p;
 314
 315         p = kmalloc(sizeof(struct dir_private_info), GFP_KERNEL);
 316         if (!p)
 317                 return NULL;
 318         p->root.rb_node = NULL;
 319         p->curr_node = NULL;
 320         p->extra_fname = NULL;
 321         p->last_pos = 0;
 322         p->curr_hash = pos2maj_hash(pos);
 323         p->curr_minor_hash = pos2min_hash(pos);
 324         p->next_hash = 0;
 325         return p;
 326 }
 327
 328 void ext4_htree_free_dir_info(struct dir_private_info *p)
 329 {
 330         free_rb_tree_fname(&p->root);
 331         kfree(p);
 332 }
 333
 334 /*
 335  * Given a directory entry, enter it into the fname rb tree.
 336  */
 337 int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,
 338                              __u32 minor_hash,
 339                              struct ext4_dir_entry_2 *dirent)
 340 {
 341         struct rb_node **p, *parent = NULL;
 342         struct fname * fname, *new_fn;
 343         struct dir_private_info *info;
 344         int len;
 345
 346         info = (struct dir_private_info *) dir_file->private_data;
 347         p = &info->root.rb_node;
 348
 349         /* Create and allocate the fname structure */
 350         len = sizeof(struct fname) + dirent->name_len + 1;
 351         new_fn = kzalloc(len, GFP_KERNEL);
 352         if (!new_fn)
 353                 return -ENOMEM;
 354         new_fn->hash = hash;
 355         new_fn->minor_hash = minor_hash;
 356         new_fn->inode = le32_to_cpu(dirent->inode);
 357         new_fn->name_len = dirent->name_len;
 358         new_fn->file_type = dirent->file_type;
 359         memcpy(new_fn->name, dirent->name, dirent->name_len);
 360         new_fn->name[dirent->name_len] = 0;
 361
 362         while (*p) {
 363                 parent = *p;
 364                 fname = rb_entry(parent, struct fname, rb_hash);
 365
 366                 /*
 367                  * If the hash and minor hash match up, then we put
 368                  * them on a linked list.  This rarely happens...
 369                  */
 370                 if ((new_fn->hash == fname->hash) &&
 371                     (new_fn->minor_hash == fname->minor_hash)) {
 372                         new_fn->next = fname->next;
 373                         fname->next = new_fn;
 374                         return 0;
 375                 }
 376
 377                 if (new_fn->hash < fname->hash)
 378                         p = &(*p)->rb_left;
 379                 else if (new_fn->hash > fname->hash)
 380                         p = &(*p)->rb_right;
 381                 else if (new_fn->minor_hash < fname->minor_hash)
 382                         p = &(*p)->rb_left;
 383                 else /* if (new_fn->minor_hash > fname->minor_hash) */
 384                         p = &(*p)->rb_right;
 385         }
 386
 387         rb_link_node(&new_fn->rb_hash, parent, p);
 388         rb_insert_color(&new_fn->rb_hash, &info->root);
 389         return 0;
 390 }
 391
 392
 393
 394 /*
 395  * This is a helper function for ext4_dx_readdir.  It calls filldir
 396  * for all entres on the fname linked list.  (Normally there is only
 397  * one entry on the linked list, unless there are 62 bit hash collisions.)
 398  */
 399 static int call_filldir(struct file * filp, void * dirent,
 400                         filldir_t filldir, struct fname *fname)
 401 {
 402         struct dir_private_info *info = filp->private_data;
 403         loff_t  curr_pos;
 404         struct inode *inode = filp->f_path.dentry->d_inode;
 405         struct super_block * sb;
 406         int error;
 407
 408         sb = inode->i_sb;
 409
 410         if (!fname) {
 411                 printk("call_filldir: called with null fname?!?\n");
 412                 return 0;
 413         }
 414         curr_pos = hash2pos(fname->hash, fname->minor_hash);
 415         while (fname) {
 416                 error = filldir(dirent, fname->name,
 417                                 fname->name_len, curr_pos,
 418                                 fname->inode,
 419                                 get_dtype(sb, fname->file_type));
 420                 if (error) {
 421                         filp->f_pos = curr_pos;
 422                         info->extra_fname = fname->next;
 423                         return error;
 424                 }
 425                 fname = fname->next;
 426         }
 427         return 0;
 428 }
 429
 430 static int ext4_dx_readdir(struct file * filp,
 431                          void * dirent, filldir_t filldir)
 432 {
 433         struct dir_private_info *info = filp->private_data;
 434         struct inode *inode = filp->f_path.dentry->d_inode;
 435         struct fname *fname;
 436         int     ret;
 437
 438         if (!info) {
 439                 info = create_dir_info(filp->f_pos);
 440                 if (!info)
 441                         return -ENOMEM;
 442                 filp->private_data = info;
 443         }
 444
 445         if (filp->f_pos == EXT4_HTREE_EOF)
 446                 return 0;       /* EOF */
 447
 448         /* Some one has messed with f_pos; reset the world */
 449         if (info->last_pos != filp->f_pos) {
 450                 free_rb_tree_fname(&info->root);
 451                 info->curr_node = NULL;
 452                 info->extra_fname = NULL;
 453                 info->curr_hash = pos2maj_hash(filp->f_pos);
 454                 info->curr_minor_hash = pos2min_hash(filp->f_pos);
 455         }
 456
 457         /*
 458          * If there are any leftover names on the hash collision
 459          * chain, return them first.
 460          */
 461         if (info->extra_fname &&
 462             call_filldir(filp, dirent, filldir, info->extra_fname))
 463                 goto finished;
 464
 465         if (!info->curr_node)
 466                 info->curr_node = rb_first(&info->root);
 467
 468         while (1) {
 469                 /*
 470                  * Fill the rbtree if we have no more entries,
 471                  * or the inode has changed since we last read in the
 472                  * cached entries.
 473                  */
 474                 if ((!info->curr_node) ||
 475                     (filp->f_version != inode->i_version)) {
 476                         info->curr_node = NULL;
 477                         free_rb_tree_fname(&info->root);
 478                         filp->f_version = inode->i_version;
 479                         ret = ext4_htree_fill_tree(filp, info->curr_hash,
 480                                                    info->curr_minor_hash,
 481                                                    &info->next_hash);
 482                         if (ret < 0)
 483                                 return ret;
 484                         if (ret == 0) {
 485                                 filp->f_pos = EXT4_HTREE_EOF;
 486                                 break;
 487                         }
 488                         info->curr_node = rb_first(&info->root);
 489                 }
 490
 491                 fname = rb_entry(info->curr_node, struct fname, rb_hash);
 492                 info->curr_hash = fname->hash;
 493                 info->curr_minor_hash = fname->minor_hash;
 494                 if (call_filldir(filp, dirent, filldir, fname))
 495                         break;
 496
 497                 info->curr_node = rb_next(info->curr_node);
 498                 if (!info->curr_node) {
 499                         if (info->next_hash == ~0) {
 500                                 filp->f_pos = EXT4_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 ext4_release_dir (struct inode * inode, struct file * filp)
 513 {
 514         if (filp->private_data)
 515                 ext4_htree_free_dir_info(filp->private_data);
 516
 517         return 0;
 518 }
 519
 520 #endif