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/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 long offset)
  68 {
  69         const char *error_msg = NULL;
  70         const int rlen = ext4_rec_len_from_disk(de->rec_len);
  71
  72         if (rlen < EXT4_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 < EXT4_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(EXT4_SB(dir->i_sb)->s_es->s_inodes_count))
  82                 error_msg = "inode out of bounds";
  83
  84         if (error_msg != NULL)
  85                 ext4_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 ext4_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 ext4_dir_entry_2 *de;
 101         struct super_block *sb;
 102         int err;
 103         struct inode *inode = filp->f_path.dentry->d_inode;
 104         int ret = 0;
 105         int dir_has_error = 0;
 106
 107         sb = inode->i_sb;
 108
 109         if (EXT4_HAS_COMPAT_FEATURE(inode->i_sb,
 110                                     EXT4_FEATURE_COMPAT_DIR_INDEX) &&
 111             ((EXT4_I(inode)->i_flags & EXT4_INDEX_FL) ||
 112              ((inode->i_size >> sb->s_blocksize_bits) == 1))) {
 113                 err = ext4_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                 EXT4_I(filp->f_path.dentry->d_inode)->i_flags &= ~EXT4_INDEX_FL;
 123         }
 124         stored = 0;
 125         offset = filp->f_pos & (sb->s_blocksize - 1);
 126
 127         while (!error && !stored && filp->f_pos < inode->i_size) {
 128                 ext4_lblk_t blk = filp->f_pos >> EXT4_BLOCK_SIZE_BITS(sb);
 129                 struct buffer_head map_bh;
 130                 struct buffer_head *bh = NULL;
 131
 132                 map_bh.b_state = 0;
 133                 err = ext4_get_blocks_wrap(NULL, inode, blk, 1, &map_bh,
 134                                                 0, 0, 0);
 135                 if (err > 0) {
 136                         pgoff_t index = map_bh.b_blocknr >>
 137                                         (PAGE_CACHE_SHIFT - inode->i_blkbits);
 138                         if (!ra_has_index(&filp->f_ra, index))
 139                                 page_cache_sync_readahead(
 140                                         sb->s_bdev->bd_inode->i_mapping,
 141                                         &filp->f_ra, filp,
 142                                         index, 1);
 143                         filp->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT;
 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                         if (!dir_has_error) {
 153                                 ext4_error(sb, __func__, "directory #%lu "
 154                                            "contains a hole at offset %Lu",
 155                                            inode->i_ino,
 156                                            (unsigned long long) filp->f_pos);
 157                                 dir_has_error = 1;
 158                         }
 159                         /* corrupt size?  Maybe no more blocks to read */
 160                         if (filp->f_pos > inode->i_blocks << 9)
 161                                 break;
 162                         filp->f_pos += sb->s_blocksize - offset;
 163                         continue;
 164                 }
 165
 166 revalidate:
 167                 /* If the dir block has changed since the last call to
 168                  * readdir(2), then we might be pointing to an invalid
 169                  * dirent right now.  Scan from the start of the block
 170                  * to make sure. */
 171                 if (filp->f_version != inode->i_version) {
 172                         for (i = 0; i < sb->s_blocksize && i < offset; ) {
 173                                 de = (struct ext4_dir_entry_2 *)
 174                                         (bh->b_data + i);
 175                                 /* It's too expensive to do a full
 176                                  * dirent test each time round this
 177                                  * loop, but we do have to test at
 178                                  * least that it is non-zero.  A
 179                                  * failure will be detected in the
 180                                  * dirent test below. */
 181                                 if (ext4_rec_len_from_disk(de->rec_len)
 182                                                 < EXT4_DIR_REC_LEN(1))
 183                                         break;
 184                                 i += ext4_rec_len_from_disk(de->rec_len);
 185                         }
 186                         offset = i;
 187                         filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1))
 188                                 | offset;
 189                         filp->f_version = inode->i_version;
 190                 }
 191
 192                 while (!error && filp->f_pos < inode->i_size
 193                        && offset < sb->s_blocksize) {
 194                         de = (struct ext4_dir_entry_2 *) (bh->b_data + offset);
 195                         if (!ext4_check_dir_entry("ext4_readdir", inode, de,
 196                                                   bh, offset)) {
 197                                 /*
 198                                  * On error, skip the f_pos to the next block
 199                                  */
 200                                 filp->f_pos = (filp->f_pos |
 201                                                 (sb->s_blocksize - 1)) + 1;
 202                                 brelse(bh);
 203                                 ret = stored;
 204                                 goto out;
 205                         }
 206                         offset += ext4_rec_len_from_disk(de->rec_len);
 207                         if (le32_to_cpu(de->inode)) {
 208                                 /* We might block in the next section
 209                                  * if the data destination is
 210                                  * currently swapped out.  So, use a
 211                                  * version stamp to detect whether or
 212                                  * not the directory has been modified
 213                                  * during the copy operation.
 214                                  */
 215                                 u64 version = filp->f_version;
 216
 217                                 error = filldir(dirent, de->name,
 218                                                 de->name_len,
 219                                                 filp->f_pos,
 220                                                 le32_to_cpu(de->inode),
 221                                                 get_dtype(sb, de->file_type));
 222                                 if (error)
 223                                         break;
 224                                 if (version != filp->f_version)
 225                                         goto revalidate;
 226                                 stored++;
 227                         }
 228                         filp->f_pos += ext4_rec_len_from_disk(de->rec_len);
 229                 }
 230                 offset = 0;
 231                 brelse(bh);
 232         }
 233 out:
 234         return ret;
 235 }
 236
 237 /*
 238  * These functions convert from the major/minor hash to an f_pos
 239  * value.
 240  *
 241  * Currently we only use major hash numer.  This is unfortunate, but
 242  * on 32-bit machines, the same VFS interface is used for lseek and
 243  * llseek, so if we use the 64 bit offset, then the 32-bit versions of
 244  * lseek/telldir/seekdir will blow out spectacularly, and from within
 245  * the ext2 low-level routine, we don't know if we're being called by
 246  * a 64-bit version of the system call or the 32-bit version of the
 247  * system call.  Worse yet, NFSv2 only allows for a 32-bit readdir
 248  * cookie.  Sigh.
 249  */
 250 #define hash2pos(major, minor)  (major >> 1)
 251 #define pos2maj_hash(pos)       ((pos << 1) & 0xffffffff)
 252 #define pos2min_hash(pos)       (0)
 253
 254 /*
 255  * This structure holds the nodes of the red-black tree used to store
 256  * the directory entry in hash order.
 257  */
 258 struct fname {
 259         __u32           hash;
 260         __u32           minor_hash;
 261         struct rb_node  rb_hash;
 262         struct fname    *next;
 263         __u32           inode;
 264         __u8            name_len;
 265         __u8            file_type;
 266         char            name[0];
 267 };
 268
 269 /*
 270  * This functoin implements a non-recursive way of freeing all of the
 271  * nodes in the red-black tree.
 272  */
 273 static void free_rb_tree_fname(struct rb_root *root)
 274 {
 275         struct rb_node  *n = root->rb_node;
 276         struct rb_node  *parent;
 277         struct fname    *fname;
 278
 279         while (n) {
 280                 /* Do the node's children first */
 281                 if (n->rb_left) {
 282                         n = n->rb_left;
 283                         continue;
 284                 }
 285                 if (n->rb_right) {
 286                         n = n->rb_right;
 287                         continue;
 288                 }
 289                 /*
 290                  * The node has no children; free it, and then zero
 291                  * out parent's link to it.  Finally go to the
 292                  * beginning of the loop and try to free the parent
 293                  * node.
 294                  */
 295                 parent = rb_parent(n);
 296                 fname = rb_entry(n, struct fname, rb_hash);
 297                 while (fname) {
 298                         struct fname *old = fname;
 299                         fname = fname->next;
 300                         kfree(old);
 301                 }
 302                 if (!parent)
 303                         root->rb_node = NULL;
 304                 else if (parent->rb_left == n)
 305                         parent->rb_left = NULL;
 306                 else if (parent->rb_right == n)
 307                         parent->rb_right = NULL;
 308                 n = parent;
 309         }
 310 }
 311
 312
 313 static struct dir_private_info *ext4_htree_create_dir_info(loff_t pos)
 314 {
 315         struct dir_private_info *p;
 316
 317         p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL);
 318         if (!p)
 319                 return NULL;
 320         p->curr_hash = pos2maj_hash(pos);
 321         p->curr_minor_hash = pos2min_hash(pos);
 322         return p;
 323 }
 324
 325 void ext4_htree_free_dir_info(struct dir_private_info *p)
 326 {
 327         free_rb_tree_fname(&p->root);
 328         kfree(p);
 329 }
 330
 331 /*
 332  * Given a directory entry, enter it into the fname rb tree.
 333  */
 334 int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,
 335                              __u32 minor_hash,
 336                              struct ext4_dir_entry_2 *dirent)
 337 {
 338         struct rb_node **p, *parent = NULL;
 339         struct fname *fname, *new_fn;
 340         struct dir_private_info *info;
 341         int len;
 342
 343         info = (struct dir_private_info *) dir_file->private_data;
 344         p = &info->root.rb_node;
 345
 346         /* Create and allocate the fname structure */
 347         len = sizeof(struct fname) + dirent->name_len + 1;
 348         new_fn = kzalloc(len, GFP_KERNEL);
 349         if (!new_fn)
 350                 return -ENOMEM;
 351         new_fn->hash = hash;
 352         new_fn->minor_hash = minor_hash;
 353         new_fn->inode = le32_to_cpu(dirent->inode);
 354         new_fn->name_len = dirent->name_len;
 355         new_fn->file_type = dirent->file_type;
 356         memcpy(new_fn->name, dirent->name, dirent->name_len);
 357         new_fn->name[dirent->name_len] = 0;
 358
 359         while (*p) {
 360                 parent = *p;
 361                 fname = rb_entry(parent, struct fname, rb_hash);
 362
 363                 /*
 364                  * If the hash and minor hash match up, then we put
 365                  * them on a linked list.  This rarely happens...
 366                  */
 367                 if ((new_fn->hash == fname->hash) &&
 368                     (new_fn->minor_hash == fname->minor_hash)) {
 369                         new_fn->next = fname->next;
 370                         fname->next = new_fn;
 371                         return 0;
 372                 }
 373
 374                 if (new_fn->hash < fname->hash)
 375                         p = &(*p)->rb_left;
 376                 else if (new_fn->hash > fname->hash)
 377                         p = &(*p)->rb_right;
 378                 else if (new_fn->minor_hash < fname->minor_hash)
 379                         p = &(*p)->rb_left;
 380                 else /* if (new_fn->minor_hash > fname->minor_hash) */
 381                         p = &(*p)->rb_right;
 382         }
 383
 384         rb_link_node(&new_fn->rb_hash, parent, p);
 385         rb_insert_color(&new_fn->rb_hash, &info->root);
 386         return 0;
 387 }
 388
 389
 390
 391 /*
 392  * This is a helper function for ext4_dx_readdir.  It calls filldir
 393  * for all entres on the fname linked list.  (Normally there is only
 394  * one entry on the linked list, unless there are 62 bit hash collisions.)
 395  */
 396 static int call_filldir(struct file *filp, void *dirent,
 397                         filldir_t filldir, struct fname *fname)
 398 {
 399         struct dir_private_info *info = filp->private_data;
 400         loff_t  curr_pos;
 401         struct inode *inode = filp->f_path.dentry->d_inode;
 402         struct super_block *sb;
 403         int error;
 404
 405         sb = inode->i_sb;
 406
 407         if (!fname) {
 408                 printk(KERN_ERR "ext4: call_filldir: called with "
 409                        "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;
 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_path.dentry->d_inode;
 433         struct fname *fname;
 434         int     ret;
 435
 436         if (!info) {
 437                 info = ext4_htree_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                 if (call_filldir(filp, dirent, filldir, info->extra_fname))
 461                         goto finished;
 462                 info->extra_fname = NULL;
 463                 goto next_node;
 464         } else if (!info->curr_node)
 465                 info->curr_node = rb_first(&info->root);
 466
 467         while (1) {
 468                 /*
 469                  * Fill the rbtree if we have no more entries,
 470                  * or the inode has changed since we last read in the
 471                  * cached entries.
 472                  */
 473                 if ((!info->curr_node) ||
 474                     (filp->f_version != inode->i_version)) {
 475                         info->curr_node = NULL;
 476                         free_rb_tree_fname(&info->root);
 477                         filp->f_version = inode->i_version;
 478                         ret = ext4_htree_fill_tree(filp, info->curr_hash,
 479                                                    info->curr_minor_hash,
 480                                                    &info->next_hash);
 481                         if (ret < 0)
 482                                 return ret;
 483                         if (ret == 0) {
 484                                 filp->f_pos = EXT4_HTREE_EOF;
 485                                 break;
 486                         }
 487                         info->curr_node = rb_first(&info->root);
 488                 }
 489
 490                 fname = rb_entry(info->curr_node, struct fname, rb_hash);
 491                 info->curr_hash = fname->hash;
 492                 info->curr_minor_hash = fname->minor_hash;
 493                 if (call_filldir(filp, dirent, filldir, fname))
 494                         break;
 495         next_node:
 496                 info->curr_node = rb_next(info->curr_node);
 497                 if (info->curr_node) {
 498                         fname = rb_entry(info->curr_node, struct fname,
 499                                          rb_hash);
 500                         info->curr_hash = fname->hash;
 501                         info->curr_minor_hash = fname->minor_hash;
 502                 } else {
 503                         if (info->next_hash == ~0) {
 504                                 filp->f_pos = EXT4_HTREE_EOF;
 505                                 break;
 506                         }
 507                         info->curr_hash = info->next_hash;
 508                         info->curr_minor_hash = 0;
 509                 }
 510         }
 511 finished:
 512         info->last_pos = filp->f_pos;
 513         return 0;
 514 }
 515
 516 static int ext4_release_dir(struct inode *inode, struct file *filp)
 517 {
 518         if (filp->private_data)
 519                 ext4_htree_free_dir_info(filp->private_data);
 520
 521         return 0;
 522 }