fs/ext3/dir.c

   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/smp_lock.h>
  29 #include <linux/slab.h>
  30 #include <linux/rbtree.h>
  31
  32 static unsigned char ext3_filetype_table[] = {
  33         DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK, DT_FIFO, DT_SOCK, DT_LNK
  34 };
  35
  36 static int ext3_readdir(struct file *, void *, filldir_t);
  37 static int ext3_dx_readdir(struct file * filp,
  38                            void * dirent, filldir_t filldir);
  39 static int ext3_release_dir (struct inode * inode,
  40                                 struct file * filp);
  41
  42 const struct file_operations ext3_dir_operations = {
  43         .llseek         = generic_file_llseek,
  44         .read           = generic_read_dir,
  45         .readdir        = ext3_readdir,         /* we take BKL. needed?*/
  46         .ioctl          = ext3_ioctl,           /* BKL held */
  47         .fsync          = ext3_sync_file,       /* BKL held */
  48 #ifdef CONFIG_EXT3_INDEX
  49         .release        = ext3_release_dir,
  50 #endif
  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 = le16_to_cpu(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_dentry->d_inode;
 104         int ret = 0;
 105
 106         sb = inode->i_sb;
 107
 108 #ifdef CONFIG_EXT3_INDEX
 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_dentry->d_inode)->i_flags &= ~EXT3_INDEX_FL;
 123         }
 124 #endif
 125         stored = 0;
 126         offset = filp->f_pos & (sb->s_blocksize - 1);
 127
 128         while (!error && !stored && filp->f_pos < inode->i_size) {
 129                 unsigned long blk = filp->f_pos >> EXT3_BLOCK_SIZE_BITS(sb);
 130                 struct buffer_head map_bh;
 131                 struct buffer_head *bh = NULL;
 132
 133                 map_bh.b_state = 0;
 134                 err = ext3_get_blocks_handle(NULL, inode, blk, 1,
 135                                                 &map_bh, 0, 0);
 136                 if (err > 0) {
 137                         page_cache_readahead(sb->s_bdev->bd_inode->i_mapping,
 138                                 &filp->f_ra,
 139                                 filp,
 140                                 map_bh.b_blocknr >>
 141                                         (PAGE_CACHE_SHIFT - inode->i_blkbits),
 142                                 1);
 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                         ext3_error (sb, "ext3_readdir",
 152                                 "directory #%lu contains a hole at offset %lu",
 153                                 inode->i_ino, (unsigned long)filp->f_pos);
 154                         filp->f_pos += sb->s_blocksize - offset;
 155                         continue;
 156                 }
 157
 158 revalidate:
 159                 /* If the dir block has changed since the last call to
 160                  * readdir(2), then we might be pointing to an invalid
 161                  * dirent right now.  Scan from the start of the block
 162                  * to make sure. */
 163                 if (filp->f_version != inode->i_version) {
 164                         for (i = 0; i < sb->s_blocksize && i < offset; ) {
 165                                 de = (struct ext3_dir_entry_2 *)
 166                                         (bh->b_data + i);
 167                                 /* It's too expensive to do a full
 168                                  * dirent test each time round this
 169                                  * loop, but we do have to test at
 170                                  * least that it is non-zero.  A
 171                                  * failure will be detected in the
 172                                  * dirent test below. */
 173                                 if (le16_to_cpu(de->rec_len) <
 174                                                 EXT3_DIR_REC_LEN(1))
 175                                         break;
 176                                 i += le16_to_cpu(de->rec_len);
 177                         }
 178                         offset = i;
 179                         filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1))
 180                                 | offset;
 181                         filp->f_version = inode->i_version;
 182                 }
 183
 184                 while (!error && filp->f_pos < inode->i_size
 185                        && offset < sb->s_blocksize) {
 186                         de = (struct ext3_dir_entry_2 *) (bh->b_data + offset);
 187                         if (!ext3_check_dir_entry ("ext3_readdir", inode, de,
 188                                                    bh, offset)) {
 189                                 /* On error, skip the f_pos to the
 190                                    next block. */
 191                                 filp->f_pos = (filp->f_pos |
 192                                                 (sb->s_blocksize - 1)) + 1;
 193                                 brelse (bh);
 194                                 ret = stored;
 195                                 goto out;
 196                         }
 197                         offset += le16_to_cpu(de->rec_len);
 198                         if (le32_to_cpu(de->inode)) {
 199                                 /* We might block in the next section
 200                                  * if the data destination is
 201                                  * currently swapped out.  So, use a
 202                                  * version stamp to detect whether or
 203                                  * not the directory has been modified
 204                                  * during the copy operation.
 205                                  */
 206                                 unsigned long version = filp->f_version;
 207
 208                                 error = filldir(dirent, de->name,
 209                                                 de->name_len,
 210                                                 filp->f_pos,
 211                                                 le32_to_cpu(de->inode),
 212                                                 get_dtype(sb, de->file_type));
 213                                 if (error)
 214                                         break;
 215                                 if (version != filp->f_version)
 216                                         goto revalidate;
 217                                 stored ++;
 218                         }
 219                         filp->f_pos += le16_to_cpu(de->rec_len);
 220                 }
 221                 offset = 0;
 222                 brelse (bh);
 223         }
 224 out:
 225         return ret;
 226 }
 227
 228 #ifdef CONFIG_EXT3_INDEX
 229 /*
 230  * These functions convert from the major/minor hash to an f_pos
 231  * value.
 232  *
 233  * Currently we only use major hash numer.  This is unfortunate, but
 234  * on 32-bit machines, the same VFS interface is used for lseek and
 235  * llseek, so if we use the 64 bit offset, then the 32-bit versions of
 236  * lseek/telldir/seekdir will blow out spectacularly, and from within
 237  * the ext2 low-level routine, we don't know if we're being called by
 238  * a 64-bit version of the system call or the 32-bit version of the
 239  * system call.  Worse yet, NFSv2 only allows for a 32-bit readdir
 240  * cookie.  Sigh.
 241  */
 242 #define hash2pos(major, minor)  (major >> 1)
 243 #define pos2maj_hash(pos)       ((pos << 1) & 0xffffffff)
 244 #define pos2min_hash(pos)       (0)
 245
 246 /*
 247  * This structure holds the nodes of the red-black tree used to store
 248  * the directory entry in hash order.
 249  */
 250 struct fname {
 251         __u32           hash;
 252         __u32           minor_hash;
 253         struct rb_node  rb_hash;
 254         struct fname    *next;
 255         __u32           inode;
 256         __u8            name_len;
 257         __u8            file_type;
 258         char            name[0];
 259 };
 260
 261 /*
 262  * This functoin implements a non-recursive way of freeing all of the
 263  * nodes in the red-black tree.
 264  */
 265 static void free_rb_tree_fname(struct rb_root *root)
 266 {
 267         struct rb_node  *n = root->rb_node;
 268         struct rb_node  *parent;
 269         struct fname    *fname;
 270
 271         while (n) {
 272                 /* Do the node's children first */
 273                 if ((n)->rb_left) {
 274                         n = n->rb_left;
 275                         continue;
 276                 }
 277                 if (n->rb_right) {
 278                         n = n->rb_right;
 279                         continue;
 280                 }
 281                 /*
 282                  * The node has no children; free it, and then zero
 283                  * out parent's link to it.  Finally go to the
 284                  * beginning of the loop and try to free the parent
 285                  * node.
 286                  */
 287                 parent = n->rb_parent;
 288                 fname = rb_entry(n, struct fname, rb_hash);
 289                 while (fname) {
 290                         struct fname * old = fname;
 291                         fname = fname->next;
 292                         kfree (old);
 293                 }
 294                 if (!parent)
 295                         root->rb_node = NULL;
 296                 else if (parent->rb_left == n)
 297                         parent->rb_left = NULL;
 298                 else if (parent->rb_right == n)
 299                         parent->rb_right = NULL;
 300                 n = parent;
 301         }
 302         root->rb_node = NULL;
 303 }
 304
 305
 306 static struct dir_private_info *create_dir_info(loff_t pos)
 307 {
 308         struct dir_private_info *p;
 309
 310         p = kmalloc(sizeof(struct dir_private_info), GFP_KERNEL);
 311         if (!p)
 312                 return NULL;
 313         p->root.rb_node = NULL;
 314         p->curr_node = NULL;
 315         p->extra_fname = NULL;
 316         p->last_pos = 0;
 317         p->curr_hash = pos2maj_hash(pos);
 318         p->curr_minor_hash = pos2min_hash(pos);
 319         p->next_hash = 0;
 320         return p;
 321 }
 322
 323 void ext3_htree_free_dir_info(struct dir_private_info *p)
 324 {
 325         free_rb_tree_fname(&p->root);
 326         kfree(p);
 327 }
 328
 329 /*
 330  * Given a directory entry, enter it into the fname rb tree.
 331  */
 332 int ext3_htree_store_dirent(struct file *dir_file, __u32 hash,
 333                              __u32 minor_hash,
 334                              struct ext3_dir_entry_2 *dirent)
 335 {
 336         struct rb_node **p, *parent = NULL;
 337         struct fname * fname, *new_fn;
 338         struct dir_private_info *info;
 339         int len;
 340
 341         info = (struct dir_private_info *) dir_file->private_data;
 342         p = &info->root.rb_node;
 343
 344         /* Create and allocate the fname structure */
 345         len = sizeof(struct fname) + dirent->name_len + 1;
 346         new_fn = kmalloc(len, GFP_KERNEL);
 347         if (!new_fn)
 348                 return -ENOMEM;
 349         memset(new_fn, 0, len);
 350         new_fn->hash = hash;
 351         new_fn->minor_hash = minor_hash;
 352         new_fn->inode = le32_to_cpu(dirent->inode);
 353         new_fn->name_len = dirent->name_len;
 354         new_fn->file_type = dirent->file_type;
 355         memcpy(new_fn->name, dirent->name, dirent->name_len);
 356         new_fn->name[dirent->name_len] = 0;
 357
 358         while (*p) {
 359                 parent = *p;
 360                 fname = rb_entry(parent, struct fname, rb_hash);
 361
 362                 /*
 363                  * If the hash and minor hash match up, then we put
 364                  * them on a linked list.  This rarely happens...
 365                  */
 366                 if ((new_fn->hash == fname->hash) &&
 367                     (new_fn->minor_hash == fname->minor_hash)) {
 368                         new_fn->next = fname->next;
 369                         fname->next = new_fn;
 370                         return 0;
 371                 }
 372
 373                 if (new_fn->hash < fname->hash)
 374                         p = &(*p)->rb_left;
 375                 else if (new_fn->hash > fname->hash)
 376                         p = &(*p)->rb_right;
 377                 else if (new_fn->minor_hash < fname->minor_hash)
 378                         p = &(*p)->rb_left;
 379                 else /* if (new_fn->minor_hash > fname->minor_hash) */
 380                         p = &(*p)->rb_right;
 381         }
 382
 383         rb_link_node(&new_fn->rb_hash, parent, p);
 384         rb_insert_color(&new_fn->rb_hash, &info->root);
 385         return 0;
 386 }
 387
 388
 389
 390 /*
 391  * This is a helper function for ext3_dx_readdir.  It calls filldir
 392  * for all entres on the fname linked list.  (Normally there is only
 393  * one entry on the linked list, unless there are 62 bit hash collisions.)
 394  */
 395 static int call_filldir(struct file * filp, void * dirent,
 396                         filldir_t filldir, struct fname *fname)
 397 {
 398         struct dir_private_info *info = filp->private_data;
 399         loff_t  curr_pos;
 400         struct inode *inode = filp->f_dentry->d_inode;
 401         struct super_block * sb;
 402         int error;
 403
 404         sb = inode->i_sb;
 405
 406         if (!fname) {
 407                 printk("call_filldir: called with null fname?!?\n");
 408                 return 0;
 409         }
 410         curr_pos = hash2pos(fname->hash, fname->minor_hash);
 411         while (fname) {
 412                 error = filldir(dirent, fname->name,
 413                                 fname->name_len, curr_pos,
 414                                 fname->inode,
 415                                 get_dtype(sb, fname->file_type));
 416                 if (error) {
 417                         filp->f_pos = curr_pos;
 418                         info->extra_fname = fname->next;
 419                         return error;
 420                 }
 421                 fname = fname->next;
 422         }
 423         return 0;
 424 }
 425
 426 static int ext3_dx_readdir(struct file * filp,
 427                          void * dirent, filldir_t filldir)
 428 {
 429         struct dir_private_info *info = filp->private_data;
 430         struct inode *inode = filp->f_dentry->d_inode;
 431         struct fname *fname;
 432         int     ret;
 433
 434         if (!info) {
 435                 info = create_dir_info(filp->f_pos);
 436                 if (!info)
 437                         return -ENOMEM;
 438                 filp->private_data = info;
 439         }
 440
 441         if (filp->f_pos == EXT3_HTREE_EOF)
 442                 return 0;       /* EOF */
 443
 444         /* Some one has messed with f_pos; reset the world */
 445         if (info->last_pos != filp->f_pos) {
 446                 free_rb_tree_fname(&info->root);
 447                 info->curr_node = NULL;
 448                 info->extra_fname = NULL;
 449                 info->curr_hash = pos2maj_hash(filp->f_pos);
 450                 info->curr_minor_hash = pos2min_hash(filp->f_pos);
 451         }
 452
 453         /*
 454          * If there are any leftover names on the hash collision
 455          * chain, return them first.
 456          */
 457         if (info->extra_fname &&
 458             call_filldir(filp, dirent, filldir, info->extra_fname))
 459                 goto finished;
 460
 461         if (!info->curr_node)
 462                 info->curr_node = rb_first(&info->root);
 463
 464         while (1) {
 465                 /*
 466                  * Fill the rbtree if we have no more entries,
 467                  * or the inode has changed since we last read in the
 468                  * cached entries.
 469                  */
 470                 if ((!info->curr_node) ||
 471                     (filp->f_version != inode->i_version)) {
 472                         info->curr_node = NULL;
 473                         free_rb_tree_fname(&info->root);
 474                         filp->f_version = inode->i_version;
 475                         ret = ext3_htree_fill_tree(filp, info->curr_hash,
 476                                                    info->curr_minor_hash,
 477                                                    &info->next_hash);
 478                         if (ret < 0)
 479                                 return ret;
 480                         if (ret == 0) {
 481                                 filp->f_pos = EXT3_HTREE_EOF;
 482                                 break;
 483                         }
 484                         info->curr_node = rb_first(&info->root);
 485                 }
 486
 487                 fname = rb_entry(info->curr_node, struct fname, rb_hash);
 488                 info->curr_hash = fname->hash;
 489                 info->curr_minor_hash = fname->minor_hash;
 490                 if (call_filldir(filp, dirent, filldir, fname))
 491                         break;
 492
 493                 info->curr_node = rb_next(info->curr_node);
 494                 if (!info->curr_node) {
 495                         if (info->next_hash == ~0) {
 496                                 filp->f_pos = EXT3_HTREE_EOF;
 497                                 break;
 498                         }
 499                         info->curr_hash = info->next_hash;
 500                         info->curr_minor_hash = 0;
 501                 }
 502         }
 503 finished:
 504         info->last_pos = filp->f_pos;
 505         return 0;
 506 }
 507
 508 static int ext3_release_dir (struct inode * inode, struct file * filp)
 509 {
 510        if (filp->private_data)
 511                 ext3_htree_free_dir_info(filp->private_data);
 512
 513         return 0;
 514 }
 515
 516 #endif