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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/buffer_head.h>
  27 #include <linux/slab.h>
  28 #include <linux/rbtree.h>
  29 #include "ext4.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         .unlocked_ioctl = ext4_ioctl,
  46 #ifdef CONFIG_COMPAT
  47         .compat_ioctl   = ext4_compat_ioctl,
  48 #endif
  49         .fsync          = ext4_sync_file,
  50         .release        = ext4_release_dir,
  51 };
  52
  53
  54 static unsigned char get_dtype(struct super_block *sb, int filetype)
  55 {
  56         if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FILETYPE) ||
  57             (filetype >= EXT4_FT_MAX))
  58                 return DT_UNKNOWN;
  59
  60         return (ext4_filetype_table[filetype]);
  61 }
  62
  63
  64 int ext4_check_dir_entry(const char *function, struct inode *dir,
  65                          struct ext4_dir_entry_2 *de,
  66                          struct buffer_head *bh,
  67                          unsigned int offset)
  68 {
  69         const char *error_msg = NULL;
  70         const int rlen = ext4_rec_len_from_disk(de->rec_len,
  71                                                 dir->i_sb->s_blocksize);
  72
  73         if (rlen < EXT4_DIR_REC_LEN(1))
  74                 error_msg = "rec_len is smaller than minimal";
  75         else if (rlen % 4 != 0)
  76                 error_msg = "rec_len % 4 != 0";
  77         else if (rlen < EXT4_DIR_REC_LEN(de->name_len))
  78                 error_msg = "rec_len is too small for name_len";
  79         else if (((char *) de - bh->b_data) + rlen > dir->i_sb->s_blocksize)
  80                 error_msg = "directory entry across blocks";
  81         else if (le32_to_cpu(de->inode) >
  82                         le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count))
  83                 error_msg = "inode out of bounds";
  84
  85         if (error_msg != NULL)
  86                 __ext4_error(dir->i_sb, function,
  87                         "bad entry in directory #%lu: %s - block=%llu"
  88                         "offset=%u(%u), inode=%u, rec_len=%d, name_len=%d",
  89                         dir->i_ino, error_msg,
  90                         (unsigned long long) bh->b_blocknr,
  91                         (unsigned) (offset%bh->b_size), offset,
  92                         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 int 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         int dir_has_error = 0;
 109
 110         sb = inode->i_sb;
 111
 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         stored = 0;
 128         offset = filp->f_pos & (sb->s_blocksize - 1);
 129
 130         while (!error && !stored && filp->f_pos < inode->i_size) {
 131                 ext4_lblk_t 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(NULL, inode, blk, 1, &map_bh, 0);
 137                 if (err > 0) {
 138                         pgoff_t index = map_bh.b_blocknr >>
 139                                         (PAGE_CACHE_SHIFT - inode->i_blkbits);
 140                         if (!ra_has_index(&filp->f_ra, index))
 141                                 page_cache_sync_readahead(
 142                                         sb->s_bdev->bd_inode->i_mapping,
 143                                         &filp->f_ra, filp,
 144                                         index, 1);
 145                         filp->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT;
 146                         bh = ext4_bread(NULL, inode, blk, 0, &err);
 147                 }
 148
 149                 /*
 150                  * We ignore I/O errors on directories so users have a chance
 151                  * of recovering data when there's a bad sector
 152                  */
 153                 if (!bh) {
 154                         if (!dir_has_error) {
 155                                 ext4_error(sb, "directory #%lu "
 156                                            "contains a hole at offset %Lu",
 157                                            inode->i_ino,
 158                                            (unsigned long long) filp->f_pos);
 159                                 dir_has_error = 1;
 160                         }
 161                         /* corrupt size?  Maybe no more blocks to read */
 162                         if (filp->f_pos > inode->i_blocks << 9)
 163                                 break;
 164                         filp->f_pos += sb->s_blocksize - offset;
 165                         continue;
 166                 }
 167
 168 revalidate:
 169                 /* If the dir block has changed since the last call to
 170                  * readdir(2), then we might be pointing to an invalid
 171                  * dirent right now.  Scan from the start of the block
 172                  * to make sure. */
 173                 if (filp->f_version != inode->i_version) {
 174                         for (i = 0; i < sb->s_blocksize && i < offset; ) {
 175                                 de = (struct ext4_dir_entry_2 *)
 176                                         (bh->b_data + i);
 177                                 /* It's too expensive to do a full
 178                                  * dirent test each time round this
 179                                  * loop, but we do have to test at
 180                                  * least that it is non-zero.  A
 181                                  * failure will be detected in the
 182                                  * dirent test below. */
 183                                 if (ext4_rec_len_from_disk(de->rec_len,
 184                                         sb->s_blocksize) < EXT4_DIR_REC_LEN(1))
 185                                         break;
 186                                 i += ext4_rec_len_from_disk(de->rec_len,
 187                                                             sb->s_blocksize);
 188                         }
 189                         offset = i;
 190                         filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1))
 191                                 | offset;
 192                         filp->f_version = inode->i_version;
 193                 }
 194
 195                 while (!error && filp->f_pos < inode->i_size
 196                        && offset < sb->s_blocksize) {
 197                         de = (struct ext4_dir_entry_2 *) (bh->b_data + offset);
 198                         if (!ext4_check_dir_entry("ext4_readdir", inode, de,
 199                                                   bh, offset)) {
 200                                 /*
 201                                  * On error, skip the f_pos to the next block
 202                                  */
 203                                 filp->f_pos = (filp->f_pos |
 204                                                 (sb->s_blocksize - 1)) + 1;
 205                                 brelse(bh);
 206                                 ret = stored;
 207                                 goto out;
 208                         }
 209                         offset += ext4_rec_len_from_disk(de->rec_len,
 210                                         sb->s_blocksize);
 211                         if (le32_to_cpu(de->inode)) {
 212                                 /* We might block in the next section
 213                                  * if the data destination is
 214                                  * currently swapped out.  So, use a
 215                                  * version stamp to detect whether or
 216                                  * not the directory has been modified
 217                                  * during the copy operation.
 218                                  */
 219                                 u64 version = filp->f_version;
 220
 221                                 error = filldir(dirent, de->name,
 222                                                 de->name_len,
 223                                                 filp->f_pos,
 224                                                 le32_to_cpu(de->inode),
 225                                                 get_dtype(sb, de->file_type));
 226                                 if (error)
 227                                         break;
 228                                 if (version != filp->f_version)
 229                                         goto revalidate;
 230                                 stored++;
 231                         }
 232                         filp->f_pos += ext4_rec_len_from_disk(de->rec_len,
 233                                                 sb->s_blocksize);
 234                 }
 235                 offset = 0;
 236                 brelse(bh);
 237         }
 238 out:
 239         return ret;
 240 }
 241
 242 /*
 243  * These functions convert from the major/minor hash to an f_pos
 244  * value.
 245  *
 246  * Currently we only use major hash numer.  This is unfortunate, but
 247  * on 32-bit machines, the same VFS interface is used for lseek and
 248  * llseek, so if we use the 64 bit offset, then the 32-bit versions of
 249  * lseek/telldir/seekdir will blow out spectacularly, and from within
 250  * the ext2 low-level routine, we don't know if we're being called by
 251  * a 64-bit version of the system call or the 32-bit version of the
 252  * system call.  Worse yet, NFSv2 only allows for a 32-bit readdir
 253  * cookie.  Sigh.
 254  */
 255 #define hash2pos(major, minor)  (major >> 1)
 256 #define pos2maj_hash(pos)       ((pos << 1) & 0xffffffff)
 257 #define pos2min_hash(pos)       (0)
 258
 259 /*
 260  * This structure holds the nodes of the red-black tree used to store
 261  * the directory entry in hash order.
 262  */
 263 struct fname {
 264         __u32           hash;
 265         __u32           minor_hash;
 266         struct rb_node  rb_hash;
 267         struct fname    *next;
 268         __u32           inode;
 269         __u8            name_len;
 270         __u8            file_type;
 271         char            name[0];
 272 };
 273
 274 /*
 275  * This functoin implements a non-recursive way of freeing all of the
 276  * nodes in the red-black tree.
 277  */
 278 static void free_rb_tree_fname(struct rb_root *root)
 279 {
 280         struct rb_node  *n = root->rb_node;
 281         struct rb_node  *parent;
 282         struct fname    *fname;
 283
 284         while (n) {
 285                 /* Do the node's children first */
 286                 if (n->rb_left) {
 287                         n = n->rb_left;
 288                         continue;
 289                 }
 290                 if (n->rb_right) {
 291                         n = n->rb_right;
 292                         continue;
 293                 }
 294                 /*
 295                  * The node has no children; free it, and then zero
 296                  * out parent's link to it.  Finally go to the
 297                  * beginning of the loop and try to free the parent
 298                  * node.
 299                  */
 300                 parent = rb_parent(n);
 301                 fname = rb_entry(n, struct fname, rb_hash);
 302                 while (fname) {
 303                         struct fname *old = fname;
 304                         fname = fname->next;
 305                         kfree(old);
 306                 }
 307                 if (!parent)
 308                         *root = RB_ROOT;
 309                 else if (parent->rb_left == n)
 310                         parent->rb_left = NULL;
 311                 else if (parent->rb_right == n)
 312                         parent->rb_right = NULL;
 313                 n = parent;
 314         }
 315 }
 316
 317
 318 static struct dir_private_info *ext4_htree_create_dir_info(loff_t pos)
 319 {
 320         struct dir_private_info *p;
 321
 322         p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL);
 323         if (!p)
 324                 return NULL;
 325         p->curr_hash = pos2maj_hash(pos);
 326         p->curr_minor_hash = pos2min_hash(pos);
 327         return p;
 328 }
 329
 330 void ext4_htree_free_dir_info(struct dir_private_info *p)
 331 {
 332         free_rb_tree_fname(&p->root);
 333         kfree(p);
 334 }
 335
 336 /*
 337  * Given a directory entry, enter it into the fname rb tree.
 338  */
 339 int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,
 340                              __u32 minor_hash,
 341                              struct ext4_dir_entry_2 *dirent)
 342 {
 343         struct rb_node **p, *parent = NULL;
 344         struct fname *fname, *new_fn;
 345         struct dir_private_info *info;
 346         int len;
 347
 348         info = (struct dir_private_info *) dir_file->private_data;
 349         p = &info->root.rb_node;
 350
 351         /* Create and allocate the fname structure */
 352         len = sizeof(struct fname) + dirent->name_len + 1;
 353         new_fn = kzalloc(len, GFP_KERNEL);
 354         if (!new_fn)
 355                 return -ENOMEM;
 356         new_fn->hash = hash;
 357         new_fn->minor_hash = minor_hash;
 358         new_fn->inode = le32_to_cpu(dirent->inode);
 359         new_fn->name_len = dirent->name_len;
 360         new_fn->file_type = dirent->file_type;
 361         memcpy(new_fn->name, dirent->name, dirent->name_len);
 362         new_fn->name[dirent->name_len] = 0;
 363
 364         while (*p) {
 365                 parent = *p;
 366                 fname = rb_entry(parent, struct fname, rb_hash);
 367
 368                 /*
 369                  * If the hash and minor hash match up, then we put
 370                  * them on a linked list.  This rarely happens...
 371                  */
 372                 if ((new_fn->hash == fname->hash) &&
 373                     (new_fn->minor_hash == fname->minor_hash)) {
 374                         new_fn->next = fname->next;
 375                         fname->next = new_fn;
 376                         return 0;
 377                 }
 378
 379                 if (new_fn->hash < fname->hash)
 380                         p = &(*p)->rb_left;
 381                 else if (new_fn->hash > fname->hash)
 382                         p = &(*p)->rb_right;
 383                 else if (new_fn->minor_hash < fname->minor_hash)
 384                         p = &(*p)->rb_left;
 385                 else /* if (new_fn->minor_hash > fname->minor_hash) */
 386                         p = &(*p)->rb_right;
 387         }
 388
 389         rb_link_node(&new_fn->rb_hash, parent, p);
 390         rb_insert_color(&new_fn->rb_hash, &info->root);
 391         return 0;
 392 }
 393
 394
 395
 396 /*
 397  * This is a helper function for ext4_dx_readdir.  It calls filldir
 398  * for all entres on the fname linked list.  (Normally there is only
 399  * one entry on the linked list, unless there are 62 bit hash collisions.)
 400  */
 401 static int call_filldir(struct file *filp, void *dirent,
 402                         filldir_t filldir, struct fname *fname)
 403 {
 404         struct dir_private_info *info = filp->private_data;
 405         loff_t  curr_pos;
 406         struct inode *inode = filp->f_path.dentry->d_inode;
 407         struct super_block *sb;
 408         int error;
 409
 410         sb = inode->i_sb;
 411
 412         if (!fname) {
 413                 printk(KERN_ERR "EXT4-fs: call_filldir: called with "
 414                        "null fname?!?\n");
 415                 return 0;
 416         }
 417         curr_pos = hash2pos(fname->hash, fname->minor_hash);
 418         while (fname) {
 419                 error = filldir(dirent, fname->name,
 420                                 fname->name_len, curr_pos,
 421                                 fname->inode,
 422                                 get_dtype(sb, fname->file_type));
 423                 if (error) {
 424                         filp->f_pos = curr_pos;
 425                         info->extra_fname = fname;
 426                         return error;
 427                 }
 428                 fname = fname->next;
 429         }
 430         return 0;
 431 }
 432
 433 static int ext4_dx_readdir(struct file *filp,
 434                          void *dirent, filldir_t filldir)
 435 {
 436         struct dir_private_info *info = filp->private_data;
 437         struct inode *inode = filp->f_path.dentry->d_inode;
 438         struct fname *fname;
 439         int     ret;
 440
 441         if (!info) {
 442                 info = ext4_htree_create_dir_info(filp->f_pos);
 443                 if (!info)
 444                         return -ENOMEM;
 445                 filp->private_data = info;
 446         }
 447
 448         if (filp->f_pos == EXT4_HTREE_EOF)
 449                 return 0;       /* EOF */
 450
 451         /* Some one has messed with f_pos; reset the world */
 452         if (info->last_pos != filp->f_pos) {
 453                 free_rb_tree_fname(&info->root);
 454                 info->curr_node = NULL;
 455                 info->extra_fname = NULL;
 456                 info->curr_hash = pos2maj_hash(filp->f_pos);
 457                 info->curr_minor_hash = pos2min_hash(filp->f_pos);
 458         }
 459
 460         /*
 461          * If there are any leftover names on the hash collision
 462          * chain, return them first.
 463          */
 464         if (info->extra_fname) {
 465                 if (call_filldir(filp, dirent, filldir, info->extra_fname))
 466                         goto finished;
 467                 info->extra_fname = NULL;
 468                 goto next_node;
 469         } else if (!info->curr_node)
 470                 info->curr_node = rb_first(&info->root);
 471
 472         while (1) {
 473                 /*
 474                  * Fill the rbtree if we have no more entries,
 475                  * or the inode has changed since we last read in the
 476                  * cached entries.
 477                  */
 478                 if ((!info->curr_node) ||
 479                     (filp->f_version != inode->i_version)) {
 480                         info->curr_node = NULL;
 481                         free_rb_tree_fname(&info->root);
 482                         filp->f_version = inode->i_version;
 483                         ret = ext4_htree_fill_tree(filp, info->curr_hash,
 484                                                    info->curr_minor_hash,
 485                                                    &info->next_hash);
 486                         if (ret < 0)
 487                                 return ret;
 488                         if (ret == 0) {
 489                                 filp->f_pos = EXT4_HTREE_EOF;
 490                                 break;
 491                         }
 492                         info->curr_node = rb_first(&info->root);
 493                 }
 494
 495                 fname = rb_entry(info->curr_node, struct fname, rb_hash);
 496                 info->curr_hash = fname->hash;
 497                 info->curr_minor_hash = fname->minor_hash;
 498                 if (call_filldir(filp, dirent, filldir, fname))
 499                         break;
 500         next_node:
 501                 info->curr_node = rb_next(info->curr_node);
 502                 if (info->curr_node) {
 503                         fname = rb_entry(info->curr_node, struct fname,
 504                                          rb_hash);
 505                         info->curr_hash = fname->hash;
 506                         info->curr_minor_hash = fname->minor_hash;
 507                 } else {
 508                         if (info->next_hash == ~0) {
 509                                 filp->f_pos = EXT4_HTREE_EOF;
 510                                 break;
 511                         }
 512                         info->curr_hash = info->next_hash;
 513                         info->curr_minor_hash = 0;
 514                 }
 515         }
 516 finished:
 517         info->last_pos = filp->f_pos;
 518         return 0;
 519 }
 520
 521 static int ext4_release_dir(struct inode *inode, struct file *filp)
 522 {
 523         if (filp->private_data)
 524                 ext4_htree_free_dir_info(filp->private_data);
 525
 526         return 0;
 527 }