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_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_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                         filp->f_pos += sb->s_blocksize - offset;
 157                         continue;
 158                 }
 159
 160 revalidate:
 161                 /* If the dir block has changed since the last call to
 162                  * readdir(2), then we might be pointing to an invalid
 163                  * dirent right now.  Scan from the start of the block
 164                  * to make sure. */
 165                 if (filp->f_version != inode->i_version) {
 166                         for (i = 0; i < sb->s_blocksize && i < offset; ) {
 167                                 de = (struct ext4_dir_entry_2 *)
 168                                         (bh->b_data + i);
 169                                 /* It's too expensive to do a full
 170                                  * dirent test each time round this
 171                                  * loop, but we do have to test at
 172                                  * least that it is non-zero.  A
 173                                  * failure will be detected in the
 174                                  * dirent test below. */
 175                                 if (le16_to_cpu(de->rec_len) <
 176                                                 EXT4_DIR_REC_LEN(1))
 177                                         break;
 178                                 i += le16_to_cpu(de->rec_len);
 179                         }
 180                         offset = i;
 181                         filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1))
 182                                 | offset;
 183                         filp->f_version = inode->i_version;
 184                 }
 185
 186                 while (!error && filp->f_pos < inode->i_size
 187                        && offset < sb->s_blocksize) {
 188                         de = (struct ext4_dir_entry_2 *) (bh->b_data + offset);
 189                         if (!ext4_check_dir_entry ("ext4_readdir", inode, de,
 190                                                    bh, offset)) {
 191                                 /*
 192                                  * On error, skip the f_pos to the next block
 193                                  */
 194                                 filp->f_pos = (filp->f_pos |
 195                                                 (sb->s_blocksize - 1)) + 1;
 196                                 brelse (bh);
 197                                 ret = stored;
 198                                 goto out;
 199                         }
 200                         offset += le16_to_cpu(de->rec_len);
 201                         if (le32_to_cpu(de->inode)) {
 202                                 /* We might block in the next section
 203                                  * if the data destination is
 204                                  * currently swapped out.  So, use a
 205                                  * version stamp to detect whether or
 206                                  * not the directory has been modified
 207                                  * during the copy operation.
 208                                  */
 209                                 unsigned long version = filp->f_version;
 210
 211                                 error = filldir(dirent, de->name,
 212                                                 de->name_len,
 213                                                 filp->f_pos,
 214                                                 le32_to_cpu(de->inode),
 215                                                 get_dtype(sb, de->file_type));
 216                                 if (error)
 217                                         break;
 218                                 if (version != filp->f_version)
 219                                         goto revalidate;
 220                                 stored ++;
 221                         }
 222                         filp->f_pos += le16_to_cpu(de->rec_len);
 223                 }
 224                 offset = 0;
 225                 brelse (bh);
 226         }
 227 out:
 228         return ret;
 229 }
 230
 231 #ifdef CONFIG_EXT4_INDEX
 232 /*
 233  * These functions convert from the major/minor hash to an f_pos
 234  * value.
 235  *
 236  * Currently we only use major hash numer.  This is unfortunate, but
 237  * on 32-bit machines, the same VFS interface is used for lseek and
 238  * llseek, so if we use the 64 bit offset, then the 32-bit versions of
 239  * lseek/telldir/seekdir will blow out spectacularly, and from within
 240  * the ext2 low-level routine, we don't know if we're being called by
 241  * a 64-bit version of the system call or the 32-bit version of the
 242  * system call.  Worse yet, NFSv2 only allows for a 32-bit readdir
 243  * cookie.  Sigh.
 244  */
 245 #define hash2pos(major, minor)  (major >> 1)
 246 #define pos2maj_hash(pos)       ((pos << 1) & 0xffffffff)
 247 #define pos2min_hash(pos)       (0)
 248
 249 /*
 250  * This structure holds the nodes of the red-black tree used to store
 251  * the directory entry in hash order.
 252  */
 253 struct fname {
 254         __u32           hash;
 255         __u32           minor_hash;
 256         struct rb_node  rb_hash;
 257         struct fname    *next;
 258         __u32           inode;
 259         __u8            name_len;
 260         __u8            file_type;
 261         char            name[0];
 262 };
 263
 264 /*
 265  * This functoin implements a non-recursive way of freeing all of the
 266  * nodes in the red-black tree.
 267  */
 268 static void free_rb_tree_fname(struct rb_root *root)
 269 {
 270         struct rb_node  *n = root->rb_node;
 271         struct rb_node  *parent;
 272         struct fname    *fname;
 273
 274         while (n) {
 275                 /* Do the node's children first */
 276                 if ((n)->rb_left) {
 277                         n = n->rb_left;
 278                         continue;
 279                 }
 280                 if (n->rb_right) {
 281                         n = n->rb_right;
 282                         continue;
 283                 }
 284                 /*
 285                  * The node has no children; free it, and then zero
 286                  * out parent's link to it.  Finally go to the
 287                  * beginning of the loop and try to free the parent
 288                  * node.
 289                  */
 290                 parent = rb_parent(n);
 291                 fname = rb_entry(n, struct fname, rb_hash);
 292                 while (fname) {
 293                         struct fname * old = fname;
 294                         fname = fname->next;
 295                         kfree (old);
 296                 }
 297                 if (!parent)
 298                         root->rb_node = NULL;
 299                 else if (parent->rb_left == n)
 300                         parent->rb_left = NULL;
 301                 else if (parent->rb_right == n)
 302                         parent->rb_right = NULL;
 303                 n = parent;
 304         }
 305         root->rb_node = NULL;
 306 }
 307
 308
 309 static struct dir_private_info *create_dir_info(loff_t pos)
 310 {
 311         struct dir_private_info *p;
 312
 313         p = kmalloc(sizeof(struct dir_private_info), GFP_KERNEL);
 314         if (!p)
 315                 return NULL;
 316         p->root.rb_node = NULL;
 317         p->curr_node = NULL;
 318         p->extra_fname = NULL;
 319         p->last_pos = 0;
 320         p->curr_hash = pos2maj_hash(pos);
 321         p->curr_minor_hash = pos2min_hash(pos);
 322         p->next_hash = 0;
 323         return p;
 324 }
 325
 326 void ext4_htree_free_dir_info(struct dir_private_info *p)
 327 {
 328         free_rb_tree_fname(&p->root);
 329         kfree(p);
 330 }
 331
 332 /*
 333  * Given a directory entry, enter it into the fname rb tree.
 334  */
 335 int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,
 336                              __u32 minor_hash,
 337                              struct ext4_dir_entry_2 *dirent)
 338 {
 339         struct rb_node **p, *parent = NULL;
 340         struct fname * fname, *new_fn;
 341         struct dir_private_info *info;
 342         int len;
 343
 344         info = (struct dir_private_info *) dir_file->private_data;
 345         p = &info->root.rb_node;
 346
 347         /* Create and allocate the fname structure */
 348         len = sizeof(struct fname) + dirent->name_len + 1;
 349         new_fn = kzalloc(len, GFP_KERNEL);
 350         if (!new_fn)
 351                 return -ENOMEM;
 352         new_fn->hash = hash;
 353         new_fn->minor_hash = minor_hash;
 354         new_fn->inode = le32_to_cpu(dirent->inode);
 355         new_fn->name_len = dirent->name_len;
 356         new_fn->file_type = dirent->file_type;
 357         memcpy(new_fn->name, dirent->name, dirent->name_len);
 358         new_fn->name[dirent->name_len] = 0;
 359
 360         while (*p) {
 361                 parent = *p;
 362                 fname = rb_entry(parent, struct fname, rb_hash);
 363
 364                 /*
 365                  * If the hash and minor hash match up, then we put
 366                  * them on a linked list.  This rarely happens...
 367                  */
 368                 if ((new_fn->hash == fname->hash) &&
 369                     (new_fn->minor_hash == fname->minor_hash)) {
 370                         new_fn->next = fname->next;
 371                         fname->next = new_fn;
 372                         return 0;
 373                 }
 374
 375                 if (new_fn->hash < fname->hash)
 376                         p = &(*p)->rb_left;
 377                 else if (new_fn->hash > fname->hash)
 378                         p = &(*p)->rb_right;
 379                 else if (new_fn->minor_hash < fname->minor_hash)
 380                         p = &(*p)->rb_left;
 381                 else /* if (new_fn->minor_hash > fname->minor_hash) */
 382                         p = &(*p)->rb_right;
 383         }
 384
 385         rb_link_node(&new_fn->rb_hash, parent, p);
 386         rb_insert_color(&new_fn->rb_hash, &info->root);
 387         return 0;
 388 }
 389
 390
 391
 392 /*
 393  * This is a helper function for ext4_dx_readdir.  It calls filldir
 394  * for all entres on the fname linked list.  (Normally there is only
 395  * one entry on the linked list, unless there are 62 bit hash collisions.)
 396  */
 397 static int call_filldir(struct file * filp, void * dirent,
 398                         filldir_t filldir, struct fname *fname)
 399 {
 400         struct dir_private_info *info = filp->private_data;
 401         loff_t  curr_pos;
 402         struct inode *inode = filp->f_dentry->d_inode;
 403         struct super_block * sb;
 404         int error;
 405
 406         sb = inode->i_sb;
 407
 408         if (!fname) {
 409                 printk("call_filldir: called with null fname?!?\n");
 410                 return 0;
 411         }
 412         curr_pos = hash2pos(fname->hash, fname->minor_hash);
 413         while (fname) {
 414                 error = filldir(dirent, fname->name,
 415                                 fname->name_len, curr_pos,
 416                                 fname->inode,
 417                                 get_dtype(sb, fname->file_type));
 418                 if (error) {
 419                         filp->f_pos = curr_pos;
 420                         info->extra_fname = fname->next;
 421                         return error;
 422                 }
 423                 fname = fname->next;
 424         }
 425         return 0;
 426 }
 427
 428 static int ext4_dx_readdir(struct file * filp,
 429                          void * dirent, filldir_t filldir)
 430 {
 431         struct dir_private_info *info = filp->private_data;
 432         struct inode *inode = filp->f_dentry->d_inode;
 433         struct fname *fname;
 434         int     ret;
 435
 436         if (!info) {
 437                 info = create_dir_info(filp->f_pos);
 438                 if (!info)
 439                         return -ENOMEM;
 440                 filp->private_data = info;
 441         }
 442
 443         if (filp->f_pos == EXT4_HTREE_EOF)
 444                 return 0;       /* EOF */
 445
 446         /* Some one has messed with f_pos; reset the world */
 447         if (info->last_pos != filp->f_pos) {
 448                 free_rb_tree_fname(&info->root);
 449                 info->curr_node = NULL;
 450                 info->extra_fname = NULL;
 451                 info->curr_hash = pos2maj_hash(filp->f_pos);
 452                 info->curr_minor_hash = pos2min_hash(filp->f_pos);
 453         }
 454
 455         /*
 456          * If there are any leftover names on the hash collision
 457          * chain, return them first.
 458          */
 459         if (info->extra_fname &&
 460             call_filldir(filp, dirent, filldir, info->extra_fname))
 461                 goto finished;
 462
 463         if (!info->curr_node)
 464                 info->curr_node = rb_first(&info->root);
 465
 466         while (1) {
 467                 /*
 468                  * Fill the rbtree if we have no more entries,
 469                  * or the inode has changed since we last read in the
 470                  * cached entries.
 471                  */
 472                 if ((!info->curr_node) ||
 473                     (filp->f_version != inode->i_version)) {
 474                         info->curr_node = NULL;
 475                         free_rb_tree_fname(&info->root);
 476                         filp->f_version = inode->i_version;
 477                         ret = ext4_htree_fill_tree(filp, info->curr_hash,
 478                                                    info->curr_minor_hash,
 479                                                    &info->next_hash);
 480                         if (ret < 0)
 481                                 return ret;
 482                         if (ret == 0) {
 483                                 filp->f_pos = EXT4_HTREE_EOF;
 484                                 break;
 485                         }
 486                         info->curr_node = rb_first(&info->root);
 487                 }
 488
 489                 fname = rb_entry(info->curr_node, struct fname, rb_hash);
 490                 info->curr_hash = fname->hash;
 491                 info->curr_minor_hash = fname->minor_hash;
 492                 if (call_filldir(filp, dirent, filldir, fname))
 493                         break;
 494
 495                 info->curr_node = rb_next(info->curr_node);
 496                 if (!info->curr_node) {
 497                         if (info->next_hash == ~0) {
 498                                 filp->f_pos = EXT4_HTREE_EOF;
 499                                 break;
 500                         }
 501                         info->curr_hash = info->next_hash;
 502                         info->curr_minor_hash = 0;
 503                 }
 504         }
 505 finished:
 506         info->last_pos = filp->f_pos;
 507         return 0;
 508 }
 509
 510 static int ext4_release_dir (struct inode * inode, struct file * filp)
 511 {
 512         if (filp->private_data)
 513                 ext4_htree_free_dir_info(filp->private_data);
 514
 515         return 0;
 516 }
 517
 518 #endif