fs/ext4/dir.c

   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/smp_lock.h>
  29 #include <linux/slab.h>
  30 #include <linux/rbtree.h>
  31
  32 static unsigned char ext4_filetype_table[] = {
  33         DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK, DT_FIFO, DT_SOCK, DT_LNK
  34 };
  35
  36 static int ext4_readdir(struct file *, void *, filldir_t);
  37 static int ext4_dx_readdir(struct file * filp,
  38                            void * dirent, filldir_t filldir);
  39 static int ext4_release_dir (struct inode * inode,
  40                                 struct file * filp);
  41
  42 const struct file_operations ext4_dir_operations = {
  43         .llseek         = generic_file_llseek,
  44         .read           = generic_read_dir,
  45         .readdir        = ext4_readdir,         /* we take BKL. needed?*/
  46         .ioctl          = ext4_ioctl,           /* BKL held */
  47 #ifdef CONFIG_COMPAT
  48         .compat_ioctl   = ext4_compat_ioctl,
  49 #endif
  50         .fsync          = ext4_sync_file,       /* BKL held */
  51 #ifdef CONFIG_EXT4_INDEX
  52         .release        = ext4_release_dir,
  53 #endif
  54 };
  55
  56
  57 static unsigned char get_dtype(struct super_block *sb, int filetype)
  58 {
  59         if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FILETYPE) ||
  60             (filetype >= EXT4_FT_MAX))
  61                 return DT_UNKNOWN;
  62
  63         return (ext4_filetype_table[filetype]);
  64 }
  65
  66
  67 int ext4_check_dir_entry (const char * function, struct inode * dir,
  68                           struct ext4_dir_entry_2 * de,
  69                           struct buffer_head * bh,
  70                           unsigned long offset)
  71 {
  72         const char * error_msg = NULL;
  73         const int rlen = le16_to_cpu(de->rec_len);
  74
  75         if (rlen < EXT4_DIR_REC_LEN(1))
  76                 error_msg = "rec_len is smaller than minimal";
  77         else if (rlen % 4 != 0)
  78                 error_msg = "rec_len % 4 != 0";
  79         else if (rlen < EXT4_DIR_REC_LEN(de->name_len))
  80                 error_msg = "rec_len is too small for name_len";
  81         else if (((char *) de - bh->b_data) + rlen > dir->i_sb->s_blocksize)
  82                 error_msg = "directory entry across blocks";
  83         else if (le32_to_cpu(de->inode) >
  84                         le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count))
  85                 error_msg = "inode out of bounds";
  86
  87         if (error_msg != NULL)
  88                 ext4_error (dir->i_sb, function,
  89                         "bad entry in directory #%lu: %s - "
  90                         "offset=%lu, inode=%lu, rec_len=%d, name_len=%d",
  91                         dir->i_ino, error_msg, offset,
  92                         (unsigned long) le32_to_cpu(de->inode),
  93                         rlen, de->name_len);
  94         return error_msg == NULL ? 1 : 0;
  95 }
  96
  97 static int ext4_readdir(struct file * filp,
  98                          void * dirent, filldir_t filldir)
  99 {
 100         int error = 0;
 101         unsigned long offset;
 102         int i, stored;
 103         struct ext4_dir_entry_2 *de;
 104         struct super_block *sb;
 105         int err;
 106         struct inode *inode = filp->f_path.dentry->d_inode;
 107         int ret = 0;
 108
 109         sb = inode->i_sb;
 110
 111 #ifdef CONFIG_EXT4_INDEX
 112         if (EXT4_HAS_COMPAT_FEATURE(inode->i_sb,
 113                                     EXT4_FEATURE_COMPAT_DIR_INDEX) &&
 114             ((EXT4_I(inode)->i_flags & EXT4_INDEX_FL) ||
 115              ((inode->i_size >> sb->s_blocksize_bits) == 1))) {
 116                 err = ext4_dx_readdir(filp, dirent, filldir);
 117                 if (err != ERR_BAD_DX_DIR) {
 118                         ret = err;
 119                         goto out;
 120                 }
 121                 /*
 122                  * We don't set the inode dirty flag since it's not
 123                  * critical that it get flushed back to the disk.
 124                  */
 125                 EXT4_I(filp->f_path.dentry->d_inode)->i_flags &= ~EXT4_INDEX_FL;
 126         }
 127 #endif
 128         stored = 0;
 129         offset = filp->f_pos & (sb->s_blocksize - 1);
 130
 131         while (!error && !stored && filp->f_pos < inode->i_size) {
 132                 unsigned long blk = filp->f_pos >> EXT4_BLOCK_SIZE_BITS(sb);
 133                 struct buffer_head map_bh;
 134                 struct buffer_head *bh = NULL;
 135
 136                 map_bh.b_state = 0;
 137                 err = ext4_get_blocks_wrap(NULL, inode, blk, 1, &map_bh, 0, 0);
 138                 if (err > 0) {
 139                         page_cache_readahead(sb->s_bdev->bd_inode->i_mapping,
 140                                 &filp->f_ra,
 141                                 filp,
 142                                 map_bh.b_blocknr >>
 143                                         (PAGE_CACHE_SHIFT - inode->i_blkbits),
 144                                 1);
 145                         bh = ext4_bread(NULL, inode, blk, 0, &err);
 146                 }
 147
 148                 /*
 149                  * We ignore I/O errors on directories so users have a chance
 150                  * of recovering data when there's a bad sector
 151                  */
 152                 if (!bh) {
 153                         ext4_error (sb, "ext4_readdir",
 154                                 "directory #%lu contains a hole at offset %lu",
 155                                 inode->i_ino, (unsigned long)filp->f_pos);
 156                         /* corrupt size?  Maybe no more blocks to read */
 157                         if (filp->f_pos > inode->i_blocks << 9)
 158                                 break;
 159                         filp->f_pos += sb->s_blocksize - offset;
 160                         continue;
 161                 }
 162
 163 revalidate:
 164                 /* If the dir block has changed since the last call to
 165                  * readdir(2), then we might be pointing to an invalid
 166                  * dirent right now.  Scan from the start of the block
 167                  * to make sure. */
 168                 if (filp->f_version != inode->i_version) {
 169                         for (i = 0; i < sb->s_blocksize && i < offset; ) {
 170                                 de = (struct ext4_dir_entry_2 *)
 171                                         (bh->b_data + i);
 172                                 /* It's too expensive to do a full
 173                                  * dirent test each time round this
 174                                  * loop, but we do have to test at
 175                                  * least that it is non-zero.  A
 176                                  * failure will be detected in the
 177                                  * dirent test below. */
 178                                 if (le16_to_cpu(de->rec_len) <
 179                                                 EXT4_DIR_REC_LEN(1))
 180                                         break;
 181                                 i += le16_to_cpu(de->rec_len);
 182                         }
 183                         offset = i;
 184                         filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1))
 185                                 | offset;
 186                         filp->f_version = inode->i_version;
 187                 }
 188
 189                 while (!error && filp->f_pos < inode->i_size
 190                        && offset < sb->s_blocksize) {
 191                         de = (struct ext4_dir_entry_2 *) (bh->b_data + offset);
 192                         if (!ext4_check_dir_entry ("ext4_readdir", inode, de,
 193                                                    bh, offset)) {
 194                                 /*
 195                                  * On error, skip the f_pos to the next block
 196                                  */
 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 += le16_to_cpu(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                                 unsigned long 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 += le16_to_cpu(de->rec_len);
 226                 }
 227                 offset = 0;
 228                 brelse (bh);
 229         }
 230 out:
 231         return ret;
 232 }
 233
 234 #ifdef CONFIG_EXT4_INDEX
 235 /*
 236  * These functions convert from the major/minor hash to an f_pos
 237  * value.
 238  *
 239  * Currently we only use major hash numer.  This is unfortunate, but
 240  * on 32-bit machines, the same VFS interface is used for lseek and
 241  * llseek, so if we use the 64 bit offset, then the 32-bit versions of
 242  * lseek/telldir/seekdir will blow out spectacularly, and from within
 243  * the ext2 low-level routine, we don't know if we're being called by
 244  * a 64-bit version of the system call or the 32-bit version of the
 245  * system call.  Worse yet, NFSv2 only allows for a 32-bit readdir
 246  * cookie.  Sigh.
 247  */
 248 #define hash2pos(major, minor)  (major >> 1)
 249 #define pos2maj_hash(pos)       ((pos << 1) & 0xffffffff)
 250 #define pos2min_hash(pos)       (0)
 251
 252 /*
 253  * This structure holds the nodes of the red-black tree used to store
 254  * the directory entry in hash order.
 255  */
 256 struct fname {
 257         __u32           hash;
 258         __u32           minor_hash;
 259         struct rb_node  rb_hash;
 260         struct fname    *next;
 261         __u32           inode;
 262         __u8            name_len;
 263         __u8            file_type;
 264         char            name[0];
 265 };
 266
 267 /*
 268  * This functoin implements a non-recursive way of freeing all of the
 269  * nodes in the red-black tree.
 270  */
 271 static void free_rb_tree_fname(struct rb_root *root)
 272 {
 273         struct rb_node  *n = root->rb_node;
 274         struct rb_node  *parent;
 275         struct fname    *fname;
 276
 277         while (n) {
 278                 /* Do the node's children first */
 279                 if ((n)->rb_left) {
 280                         n = n->rb_left;
 281                         continue;
 282                 }
 283                 if (n->rb_right) {
 284                         n = n->rb_right;
 285                         continue;
 286                 }
 287                 /*
 288                  * The node has no children; free it, and then zero
 289                  * out parent's link to it.  Finally go to the
 290                  * beginning of the loop and try to free the parent
 291                  * node.
 292                  */
 293                 parent = rb_parent(n);
 294                 fname = rb_entry(n, struct fname, rb_hash);
 295                 while (fname) {
 296                         struct fname * old = fname;
 297                         fname = fname->next;
 298                         kfree (old);
 299                 }
 300                 if (!parent)
 301                         root->rb_node = NULL;
 302                 else if (parent->rb_left == n)
 303                         parent->rb_left = NULL;
 304                 else if (parent->rb_right == n)
 305                         parent->rb_right = NULL;
 306                 n = parent;
 307         }
 308         root->rb_node = NULL;
 309 }
 310
 311
 312 static struct dir_private_info *create_dir_info(loff_t pos)
 313 {
 314         struct dir_private_info *p;
 315
 316         p = kmalloc(sizeof(struct dir_private_info), GFP_KERNEL);
 317         if (!p)
 318                 return NULL;
 319         p->root.rb_node = NULL;
 320         p->curr_node = NULL;
 321         p->extra_fname = NULL;
 322         p->last_pos = 0;
 323         p->curr_hash = pos2maj_hash(pos);
 324         p->curr_minor_hash = pos2min_hash(pos);
 325         p->next_hash = 0;
 326         return p;
 327 }
 328
 329 void ext4_htree_free_dir_info(struct dir_private_info *p)
 330 {
 331         free_rb_tree_fname(&p->root);
 332         kfree(p);
 333 }
 334
 335 /*
 336  * Given a directory entry, enter it into the fname rb tree.
 337  */
 338 int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,
 339                              __u32 minor_hash,
 340                              struct ext4_dir_entry_2 *dirent)
 341 {
 342         struct rb_node **p, *parent = NULL;
 343         struct fname * fname, *new_fn;
 344         struct dir_private_info *info;
 345         int len;
 346
 347         info = (struct dir_private_info *) dir_file->private_data;
 348         p = &info->root.rb_node;
 349
 350         /* Create and allocate the fname structure */
 351         len = sizeof(struct fname) + dirent->name_len + 1;
 352         new_fn = kzalloc(len, GFP_KERNEL);
 353         if (!new_fn)
 354                 return -ENOMEM;
 355         new_fn->hash = hash;
 356         new_fn->minor_hash = minor_hash;
 357         new_fn->inode = le32_to_cpu(dirent->inode);
 358         new_fn->name_len = dirent->name_len;
 359         new_fn->file_type = dirent->file_type;
 360         memcpy(new_fn->name, dirent->name, dirent->name_len);
 361         new_fn->name[dirent->name_len] = 0;
 362
 363         while (*p) {
 364                 parent = *p;
 365                 fname = rb_entry(parent, struct fname, rb_hash);
 366
 367                 /*
 368                  * If the hash and minor hash match up, then we put
 369                  * them on a linked list.  This rarely happens...
 370                  */
 371                 if ((new_fn->hash == fname->hash) &&
 372                     (new_fn->minor_hash == fname->minor_hash)) {
 373                         new_fn->next = fname->next;
 374                         fname->next = new_fn;
 375                         return 0;
 376                 }
 377
 378                 if (new_fn->hash < fname->hash)
 379                         p = &(*p)->rb_left;
 380                 else if (new_fn->hash > fname->hash)
 381                         p = &(*p)->rb_right;
 382                 else if (new_fn->minor_hash < fname->minor_hash)
 383                         p = &(*p)->rb_left;
 384                 else /* if (new_fn->minor_hash > fname->minor_hash) */
 385                         p = &(*p)->rb_right;
 386         }
 387
 388         rb_link_node(&new_fn->rb_hash, parent, p);
 389         rb_insert_color(&new_fn->rb_hash, &info->root);
 390         return 0;
 391 }
 392
 393
 394
 395 /*
 396  * This is a helper function for ext4_dx_readdir.  It calls filldir
 397  * for all entres on the fname linked list.  (Normally there is only
 398  * one entry on the linked list, unless there are 62 bit hash collisions.)
 399  */
 400 static int call_filldir(struct file * filp, void * dirent,
 401                         filldir_t filldir, struct fname *fname)
 402 {
 403         struct dir_private_info *info = filp->private_data;
 404         loff_t  curr_pos;
 405         struct inode *inode = filp->f_path.dentry->d_inode;
 406         struct super_block * sb;
 407         int error;
 408
 409         sb = inode->i_sb;
 410
 411         if (!fname) {
 412                 printk("call_filldir: called with null fname?!?\n");
 413                 return 0;
 414         }
 415         curr_pos = hash2pos(fname->hash, fname->minor_hash);
 416         while (fname) {
 417                 error = filldir(dirent, fname->name,
 418                                 fname->name_len, curr_pos,
 419                                 fname->inode,
 420                                 get_dtype(sb, fname->file_type));
 421                 if (error) {
 422                         filp->f_pos = curr_pos;
 423                         info->extra_fname = fname->next;
 424                         return error;
 425                 }
 426                 fname = fname->next;
 427         }
 428         return 0;
 429 }
 430
 431 static int ext4_dx_readdir(struct file * filp,
 432                          void * dirent, filldir_t filldir)
 433 {
 434         struct dir_private_info *info = filp->private_data;
 435         struct inode *inode = filp->f_path.dentry->d_inode;
 436         struct fname *fname;
 437         int     ret;
 438
 439         if (!info) {
 440                 info = create_dir_info(filp->f_pos);
 441                 if (!info)
 442                         return -ENOMEM;
 443                 filp->private_data = info;
 444         }
 445
 446         if (filp->f_pos == EXT4_HTREE_EOF)
 447                 return 0;       /* EOF */
 448
 449         /* Some one has messed with f_pos; reset the world */
 450         if (info->last_pos != filp->f_pos) {
 451                 free_rb_tree_fname(&info->root);
 452                 info->curr_node = NULL;
 453                 info->extra_fname = NULL;
 454                 info->curr_hash = pos2maj_hash(filp->f_pos);
 455                 info->curr_minor_hash = pos2min_hash(filp->f_pos);
 456         }
 457
 458         /*
 459          * If there are any leftover names on the hash collision
 460          * chain, return them first.
 461          */
 462         if (info->extra_fname &&
 463             call_filldir(filp, dirent, filldir, info->extra_fname))
 464                 goto finished;
 465
 466         if (!info->curr_node)
 467                 info->curr_node = rb_first(&info->root);
 468
 469         while (1) {
 470                 /*
 471                  * Fill the rbtree if we have no more entries,
 472                  * or the inode has changed since we last read in the
 473                  * cached entries.
 474                  */
 475                 if ((!info->curr_node) ||
 476                     (filp->f_version != inode->i_version)) {
 477                         info->curr_node = NULL;
 478                         free_rb_tree_fname(&info->root);
 479                         filp->f_version = inode->i_version;
 480                         ret = ext4_htree_fill_tree(filp, info->curr_hash,
 481                                                    info->curr_minor_hash,
 482                                                    &info->next_hash);
 483                         if (ret < 0)
 484                                 return ret;
 485                         if (ret == 0) {
 486                                 filp->f_pos = EXT4_HTREE_EOF;
 487                                 break;
 488                         }
 489                         info->curr_node = rb_first(&info->root);
 490                 }
 491
 492                 fname = rb_entry(info->curr_node, struct fname, rb_hash);
 493                 info->curr_hash = fname->hash;
 494                 info->curr_minor_hash = fname->minor_hash;
 495                 if (call_filldir(filp, dirent, filldir, fname))
 496                         break;
 497
 498                 info->curr_node = rb_next(info->curr_node);
 499                 if (!info->curr_node) {
 500                         if (info->next_hash == ~0) {
 501                                 filp->f_pos = EXT4_HTREE_EOF;
 502                                 break;
 503                         }
 504                         info->curr_hash = info->next_hash;
 505                         info->curr_minor_hash = 0;
 506                 }
 507         }
 508 finished:
 509         info->last_pos = filp->f_pos;
 510         return 0;
 511 }
 512
 513 static int ext4_release_dir (struct inode * inode, struct file * filp)
 514 {
 515         if (filp->private_data)
 516                 ext4_htree_free_dir_info(filp->private_data);
 517
 518         return 0;
 519 }
 520
 521 #endif