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 #include "xattr.h"
  31
  32 static int ext4_dx_readdir(struct file *filp,
  33                            void *dirent, filldir_t filldir);
  34
  35 /**
  36  * Check if the given dir-inode refers to an htree-indexed directory
  37  * (or a directory which chould potentially get coverted to use htree
  38  * indexing).
  39  *
  40  * Return 1 if it is a dx dir, 0 if not
  41  */
  42 static int is_dx_dir(struct inode *inode)
  43 {
  44         struct super_block *sb = inode->i_sb;
  45
  46         if (EXT4_HAS_COMPAT_FEATURE(inode->i_sb,
  47                      EXT4_FEATURE_COMPAT_DIR_INDEX) &&
  48             ((ext4_test_inode_flag(inode, EXT4_INODE_INDEX)) ||
  49              ((inode->i_size >> sb->s_blocksize_bits) == 1) ||
  50              ext4_has_inline_data(inode)))
  51                 return 1;
  52
  53         return 0;
  54 }
  55
  56 /*
  57  * Return 0 if the directory entry is OK, and 1 if there is a problem
  58  *
  59  * Note: this is the opposite of what ext2 and ext3 historically returned...
  60  *
  61  * bh passed here can be an inode block or a dir data block, depending
  62  * on the inode inline data flag.
  63  */
  64 int __ext4_check_dir_entry(const char *function, unsigned int line,
  65                            struct inode *dir, struct file *filp,
  66                            struct ext4_dir_entry_2 *de,
  67                            struct buffer_head *bh, char *buf, int size,
  68                            unsigned int offset)
  69 {
  70         const char *error_msg = NULL;
  71         const int rlen = ext4_rec_len_from_disk(de->rec_len,
  72                                                 dir->i_sb->s_blocksize);
  73
  74         if (unlikely(rlen < EXT4_DIR_REC_LEN(1)))
  75                 error_msg = "rec_len is smaller than minimal";
  76         else if (unlikely(rlen % 4 != 0))
  77                 error_msg = "rec_len % 4 != 0";
  78         else if (unlikely(rlen < EXT4_DIR_REC_LEN(de->name_len)))
  79                 error_msg = "rec_len is too small for name_len";
  80         else if (unlikely(((char *) de - buf) + rlen > size))
  81                 error_msg = "directory entry across range";
  82         else if (unlikely(le32_to_cpu(de->inode) >
  83                         le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count)))
  84                 error_msg = "inode out of bounds";
  85         else
  86                 return 0;
  87
  88         if (filp)
  89                 ext4_error_file(filp, function, line, bh->b_blocknr,
  90                                 "bad entry in directory: %s - offset=%u(%u), "
  91                                 "inode=%u, rec_len=%d, name_len=%d",
  92                                 error_msg, (unsigned) (offset % size),
  93                                 offset, le32_to_cpu(de->inode),
  94                                 rlen, de->name_len);
  95         else
  96                 ext4_error_inode(dir, function, line, bh->b_blocknr,
  97                                 "bad entry in directory: %s - offset=%u(%u), "
  98                                 "inode=%u, rec_len=%d, name_len=%d",
  99                                 error_msg, (unsigned) (offset % size),
 100                                 offset, le32_to_cpu(de->inode),
 101                                 rlen, de->name_len);
 102
 103         return 1;
 104 }
 105
 106 static int ext4_readdir(struct file *filp,
 107                          void *dirent, filldir_t filldir)
 108 {
 109         int error = 0;
 110         unsigned int offset;
 111         int i, stored;
 112         struct ext4_dir_entry_2 *de;
 113         int err;
 114         struct inode *inode = file_inode(filp);
 115         struct super_block *sb = inode->i_sb;
 116         int ret = 0;
 117         int dir_has_error = 0;
 118
 119         if (is_dx_dir(inode)) {
 120                 err = ext4_dx_readdir(filp, dirent, filldir);
 121                 if (err != ERR_BAD_DX_DIR) {
 122                         ret = err;
 123                         goto out;
 124                 }
 125                 /*
 126                  * We don't set the inode dirty flag since it's not
 127                  * critical that it get flushed back to the disk.
 128                  */
 129                 ext4_clear_inode_flag(file_inode(filp),
 130                                       EXT4_INODE_INDEX);
 131         }
 132
 133         if (ext4_has_inline_data(inode)) {
 134                 int has_inline_data = 1;
 135                 ret = ext4_read_inline_dir(filp, dirent, filldir,
 136                                            &has_inline_data);
 137                 if (has_inline_data)
 138                         return ret;
 139         }
 140
 141         stored = 0;
 142         offset = filp->f_pos & (sb->s_blocksize - 1);
 143
 144         while (!error && !stored && filp->f_pos < inode->i_size) {
 145                 struct ext4_map_blocks map;
 146                 struct buffer_head *bh = NULL;
 147
 148                 map.m_lblk = filp->f_pos >> EXT4_BLOCK_SIZE_BITS(sb);
 149                 map.m_len = 1;
 150                 err = ext4_map_blocks(NULL, inode, &map, 0);
 151                 if (err > 0) {
 152                         pgoff_t index = map.m_pblk >>
 153                                         (PAGE_CACHE_SHIFT - inode->i_blkbits);
 154                         if (!ra_has_index(&filp->f_ra, index))
 155                                 page_cache_sync_readahead(
 156                                         sb->s_bdev->bd_inode->i_mapping,
 157                                         &filp->f_ra, filp,
 158                                         index, 1);
 159                         filp->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT;
 160                         bh = ext4_bread(NULL, inode, map.m_lblk, 0, &err);
 161                 }
 162
 163                 /*
 164                  * We ignore I/O errors on directories so users have a chance
 165                  * of recovering data when there's a bad sector
 166                  */
 167                 if (!bh) {
 168                         if (!dir_has_error) {
 169                                 EXT4_ERROR_FILE(filp, 0,
 170                                                 "directory contains a "
 171                                                 "hole at offset %llu",
 172                                            (unsigned long long) filp->f_pos);
 173                                 dir_has_error = 1;
 174                         }
 175                         /* corrupt size?  Maybe no more blocks to read */
 176                         if (filp->f_pos > inode->i_blocks << 9)
 177                                 break;
 178                         filp->f_pos += sb->s_blocksize - offset;
 179                         continue;
 180                 }
 181
 182                 /* Check the checksum */
 183                 if (!buffer_verified(bh) &&
 184                     !ext4_dirent_csum_verify(inode,
 185                                 (struct ext4_dir_entry *)bh->b_data)) {
 186                         EXT4_ERROR_FILE(filp, 0, "directory fails checksum "
 187                                         "at offset %llu",
 188                                         (unsigned long long)filp->f_pos);
 189                         filp->f_pos += sb->s_blocksize - offset;
 190                         brelse(bh);
 191                         continue;
 192                 }
 193                 set_buffer_verified(bh);
 194
 195 revalidate:
 196                 /* If the dir block has changed since the last call to
 197                  * readdir(2), then we might be pointing to an invalid
 198                  * dirent right now.  Scan from the start of the block
 199                  * to make sure. */
 200                 if (filp->f_version != inode->i_version) {
 201                         for (i = 0; i < sb->s_blocksize && i < offset; ) {
 202                                 de = (struct ext4_dir_entry_2 *)
 203                                         (bh->b_data + i);
 204                                 /* It's too expensive to do a full
 205                                  * dirent test each time round this
 206                                  * loop, but we do have to test at
 207                                  * least that it is non-zero.  A
 208                                  * failure will be detected in the
 209                                  * dirent test below. */
 210                                 if (ext4_rec_len_from_disk(de->rec_len,
 211                                         sb->s_blocksize) < EXT4_DIR_REC_LEN(1))
 212                                         break;
 213                                 i += ext4_rec_len_from_disk(de->rec_len,
 214                                                             sb->s_blocksize);
 215                         }
 216                         offset = i;
 217                         filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1))
 218                                 | offset;
 219                         filp->f_version = inode->i_version;
 220                 }
 221
 222                 while (!error && filp->f_pos < inode->i_size
 223                        && offset < sb->s_blocksize) {
 224                         de = (struct ext4_dir_entry_2 *) (bh->b_data + offset);
 225                         if (ext4_check_dir_entry(inode, filp, de, bh,
 226                                                  bh->b_data, bh->b_size,
 227                                                  offset)) {
 228                                 /*
 229                                  * On error, skip the f_pos to the next block
 230                                  */
 231                                 filp->f_pos = (filp->f_pos |
 232                                                 (sb->s_blocksize - 1)) + 1;
 233                                 brelse(bh);
 234                                 ret = stored;
 235                                 goto out;
 236                         }
 237                         offset += ext4_rec_len_from_disk(de->rec_len,
 238                                         sb->s_blocksize);
 239                         if (le32_to_cpu(de->inode)) {
 240                                 /* We might block in the next section
 241                                  * if the data destination is
 242                                  * currently swapped out.  So, use a
 243                                  * version stamp to detect whether or
 244                                  * not the directory has been modified
 245                                  * during the copy operation.
 246                                  */
 247                                 u64 version = filp->f_version;
 248
 249                                 error = filldir(dirent, de->name,
 250                                                 de->name_len,
 251                                                 filp->f_pos,
 252                                                 le32_to_cpu(de->inode),
 253                                                 get_dtype(sb, de->file_type));
 254                                 if (error)
 255                                         break;
 256                                 if (version != filp->f_version)
 257                                         goto revalidate;
 258                                 stored++;
 259                         }
 260                         filp->f_pos += ext4_rec_len_from_disk(de->rec_len,
 261                                                 sb->s_blocksize);
 262                 }
 263                 offset = 0;
 264                 brelse(bh);
 265         }
 266 out:
 267         return ret;
 268 }
 269
 270 static inline int is_32bit_api(void)
 271 {
 272 #ifdef CONFIG_COMPAT
 273         return is_compat_task();
 274 #else
 275         return (BITS_PER_LONG == 32);
 276 #endif
 277 }
 278
 279 /*
 280  * These functions convert from the major/minor hash to an f_pos
 281  * value for dx directories
 282  *
 283  * Upper layer (for example NFS) should specify FMODE_32BITHASH or
 284  * FMODE_64BITHASH explicitly. On the other hand, we allow ext4 to be mounted
 285  * directly on both 32-bit and 64-bit nodes, under such case, neither
 286  * FMODE_32BITHASH nor FMODE_64BITHASH is specified.
 287  */
 288 static inline loff_t hash2pos(struct file *filp, __u32 major, __u32 minor)
 289 {
 290         if ((filp->f_mode & FMODE_32BITHASH) ||
 291             (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
 292                 return major >> 1;
 293         else
 294                 return ((__u64)(major >> 1) << 32) | (__u64)minor;
 295 }
 296
 297 static inline __u32 pos2maj_hash(struct file *filp, loff_t pos)
 298 {
 299         if ((filp->f_mode & FMODE_32BITHASH) ||
 300             (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
 301                 return (pos << 1) & 0xffffffff;
 302         else
 303                 return ((pos >> 32) << 1) & 0xffffffff;
 304 }
 305
 306 static inline __u32 pos2min_hash(struct file *filp, loff_t pos)
 307 {
 308         if ((filp->f_mode & FMODE_32BITHASH) ||
 309             (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
 310                 return 0;
 311         else
 312                 return pos & 0xffffffff;
 313 }
 314
 315 /*
 316  * Return 32- or 64-bit end-of-file for dx directories
 317  */
 318 static inline loff_t ext4_get_htree_eof(struct file *filp)
 319 {
 320         if ((filp->f_mode & FMODE_32BITHASH) ||
 321             (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
 322                 return EXT4_HTREE_EOF_32BIT;
 323         else
 324                 return EXT4_HTREE_EOF_64BIT;
 325 }
 326
 327
 328 /*
 329  * ext4_dir_llseek() calls generic_file_llseek_size to handle htree
 330  * directories, where the "offset" is in terms of the filename hash
 331  * value instead of the byte offset.
 332  *
 333  * Because we may return a 64-bit hash that is well beyond offset limits,
 334  * we need to pass the max hash as the maximum allowable offset in
 335  * the htree directory case.
 336  *
 337  * For non-htree, ext4_llseek already chooses the proper max offset.
 338  */
 339 static loff_t ext4_dir_llseek(struct file *file, loff_t offset, int whence)
 340 {
 341         struct inode *inode = file->f_mapping->host;
 342         int dx_dir = is_dx_dir(inode);
 343         loff_t htree_max = ext4_get_htree_eof(file);
 344
 345         if (likely(dx_dir))
 346                 return generic_file_llseek_size(file, offset, whence,
 347                                                     htree_max, htree_max);
 348         else
 349                 return ext4_llseek(file, offset, whence);
 350 }
 351
 352 /*
 353  * This structure holds the nodes of the red-black tree used to store
 354  * the directory entry in hash order.
 355  */
 356 struct fname {
 357         __u32           hash;
 358         __u32           minor_hash;
 359         struct rb_node  rb_hash;
 360         struct fname    *next;
 361         __u32           inode;
 362         __u8            name_len;
 363         __u8            file_type;
 364         char            name[0];
 365 };
 366
 367 /*
 368  * This functoin implements a non-recursive way of freeing all of the
 369  * nodes in the red-black tree.
 370  */
 371 static void free_rb_tree_fname(struct rb_root *root)
 372 {
 373         struct rb_node  *n = root->rb_node;
 374         struct rb_node  *parent;
 375         struct fname    *fname;
 376
 377         while (n) {
 378                 /* Do the node's children first */
 379                 if (n->rb_left) {
 380                         n = n->rb_left;
 381                         continue;
 382                 }
 383                 if (n->rb_right) {
 384                         n = n->rb_right;
 385                         continue;
 386                 }
 387                 /*
 388                  * The node has no children; free it, and then zero
 389                  * out parent's link to it.  Finally go to the
 390                  * beginning of the loop and try to free the parent
 391                  * node.
 392                  */
 393                 parent = rb_parent(n);
 394                 fname = rb_entry(n, struct fname, rb_hash);
 395                 while (fname) {
 396                         struct fname *old = fname;
 397                         fname = fname->next;
 398                         kfree(old);
 399                 }
 400                 if (!parent)
 401                         *root = RB_ROOT;
 402                 else if (parent->rb_left == n)
 403                         parent->rb_left = NULL;
 404                 else if (parent->rb_right == n)
 405                         parent->rb_right = NULL;
 406                 n = parent;
 407         }
 408 }
 409
 410
 411 static struct dir_private_info *ext4_htree_create_dir_info(struct file *filp,
 412                                                            loff_t pos)
 413 {
 414         struct dir_private_info *p;
 415
 416         p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL);
 417         if (!p)
 418                 return NULL;
 419         p->curr_hash = pos2maj_hash(filp, pos);
 420         p->curr_minor_hash = pos2min_hash(filp, pos);
 421         return p;
 422 }
 423
 424 void ext4_htree_free_dir_info(struct dir_private_info *p)
 425 {
 426         free_rb_tree_fname(&p->root);
 427         kfree(p);
 428 }
 429
 430 /*
 431  * Given a directory entry, enter it into the fname rb tree.
 432  */
 433 int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,
 434                              __u32 minor_hash,
 435                              struct ext4_dir_entry_2 *dirent)
 436 {
 437         struct rb_node **p, *parent = NULL;
 438         struct fname *fname, *new_fn;
 439         struct dir_private_info *info;
 440         int len;
 441
 442         info = dir_file->private_data;
 443         p = &info->root.rb_node;
 444
 445         /* Create and allocate the fname structure */
 446         len = sizeof(struct fname) + dirent->name_len + 1;
 447         new_fn = kzalloc(len, GFP_KERNEL);
 448         if (!new_fn)
 449                 return -ENOMEM;
 450         new_fn->hash = hash;
 451         new_fn->minor_hash = minor_hash;
 452         new_fn->inode = le32_to_cpu(dirent->inode);
 453         new_fn->name_len = dirent->name_len;
 454         new_fn->file_type = dirent->file_type;
 455         memcpy(new_fn->name, dirent->name, dirent->name_len);
 456         new_fn->name[dirent->name_len] = 0;
 457
 458         while (*p) {
 459                 parent = *p;
 460                 fname = rb_entry(parent, struct fname, rb_hash);
 461
 462                 /*
 463                  * If the hash and minor hash match up, then we put
 464                  * them on a linked list.  This rarely happens...
 465                  */
 466                 if ((new_fn->hash == fname->hash) &&
 467                     (new_fn->minor_hash == fname->minor_hash)) {
 468                         new_fn->next = fname->next;
 469                         fname->next = new_fn;
 470                         return 0;
 471                 }
 472
 473                 if (new_fn->hash < fname->hash)
 474                         p = &(*p)->rb_left;
 475                 else if (new_fn->hash > fname->hash)
 476                         p = &(*p)->rb_right;
 477                 else if (new_fn->minor_hash < fname->minor_hash)
 478                         p = &(*p)->rb_left;
 479                 else /* if (new_fn->minor_hash > fname->minor_hash) */
 480                         p = &(*p)->rb_right;
 481         }
 482
 483         rb_link_node(&new_fn->rb_hash, parent, p);
 484         rb_insert_color(&new_fn->rb_hash, &info->root);
 485         return 0;
 486 }
 487
 488
 489
 490 /*
 491  * This is a helper function for ext4_dx_readdir.  It calls filldir
 492  * for all entres on the fname linked list.  (Normally there is only
 493  * one entry on the linked list, unless there are 62 bit hash collisions.)
 494  */
 495 static int call_filldir(struct file *filp, void *dirent,
 496                         filldir_t filldir, struct fname *fname)
 497 {
 498         struct dir_private_info *info = filp->private_data;
 499         loff_t  curr_pos;
 500         struct inode *inode = file_inode(filp);
 501         struct super_block *sb;
 502         int error;
 503
 504         sb = inode->i_sb;
 505
 506         if (!fname) {
 507                 ext4_msg(sb, KERN_ERR, "%s:%d: inode #%lu: comm %s: "
 508                          "called with null fname?!?", __func__, __LINE__,
 509                          inode->i_ino, current->comm);
 510                 return 0;
 511         }
 512         curr_pos = hash2pos(filp, fname->hash, fname->minor_hash);
 513         while (fname) {
 514                 error = filldir(dirent, fname->name,
 515                                 fname->name_len, curr_pos,
 516                                 fname->inode,
 517                                 get_dtype(sb, fname->file_type));
 518                 if (error) {
 519                         filp->f_pos = curr_pos;
 520                         info->extra_fname = fname;
 521                         return error;
 522                 }
 523                 fname = fname->next;
 524         }
 525         return 0;
 526 }
 527
 528 static int ext4_dx_readdir(struct file *filp,
 529                          void *dirent, filldir_t filldir)
 530 {
 531         struct dir_private_info *info = filp->private_data;
 532         struct inode *inode = file_inode(filp);
 533         struct fname *fname;
 534         int     ret;
 535
 536         if (!info) {
 537                 info = ext4_htree_create_dir_info(filp, filp->f_pos);
 538                 if (!info)
 539                         return -ENOMEM;
 540                 filp->private_data = info;
 541         }
 542
 543         if (filp->f_pos == ext4_get_htree_eof(filp))
 544                 return 0;       /* EOF */
 545
 546         /* Some one has messed with f_pos; reset the world */
 547         if (info->last_pos != filp->f_pos) {
 548                 free_rb_tree_fname(&info->root);
 549                 info->curr_node = NULL;
 550                 info->extra_fname = NULL;
 551                 info->curr_hash = pos2maj_hash(filp, filp->f_pos);
 552                 info->curr_minor_hash = pos2min_hash(filp, filp->f_pos);
 553         }
 554
 555         /*
 556          * If there are any leftover names on the hash collision
 557          * chain, return them first.
 558          */
 559         if (info->extra_fname) {
 560                 if (call_filldir(filp, dirent, filldir, info->extra_fname))
 561                         goto finished;
 562                 info->extra_fname = NULL;
 563                 goto next_node;
 564         } else if (!info->curr_node)
 565                 info->curr_node = rb_first(&info->root);
 566
 567         while (1) {
 568                 /*
 569                  * Fill the rbtree if we have no more entries,
 570                  * or the inode has changed since we last read in the
 571                  * cached entries.
 572                  */
 573                 if ((!info->curr_node) ||
 574                     (filp->f_version != inode->i_version)) {
 575                         info->curr_node = NULL;
 576                         free_rb_tree_fname(&info->root);
 577                         filp->f_version = inode->i_version;
 578                         ret = ext4_htree_fill_tree(filp, info->curr_hash,
 579                                                    info->curr_minor_hash,
 580                                                    &info->next_hash);
 581                         if (ret < 0)
 582                                 return ret;
 583                         if (ret == 0) {
 584                                 filp->f_pos = ext4_get_htree_eof(filp);
 585                                 break;
 586                         }
 587                         info->curr_node = rb_first(&info->root);
 588                 }
 589
 590                 fname = rb_entry(info->curr_node, struct fname, rb_hash);
 591                 info->curr_hash = fname->hash;
 592                 info->curr_minor_hash = fname->minor_hash;
 593                 if (call_filldir(filp, dirent, filldir, fname))
 594                         break;
 595         next_node:
 596                 info->curr_node = rb_next(info->curr_node);
 597                 if (info->curr_node) {
 598                         fname = rb_entry(info->curr_node, struct fname,
 599                                          rb_hash);
 600                         info->curr_hash = fname->hash;
 601                         info->curr_minor_hash = fname->minor_hash;
 602                 } else {
 603                         if (info->next_hash == ~0) {
 604                                 filp->f_pos = ext4_get_htree_eof(filp);
 605                                 break;
 606                         }
 607                         info->curr_hash = info->next_hash;
 608                         info->curr_minor_hash = 0;
 609                 }
 610         }
 611 finished:
 612         info->last_pos = filp->f_pos;
 613         return 0;
 614 }
 615
 616 static int ext4_release_dir(struct inode *inode, struct file *filp)
 617 {
 618         if (filp->private_data)
 619                 ext4_htree_free_dir_info(filp->private_data);
 620
 621         return 0;
 622 }
 623
 624 const struct file_operations ext4_dir_operations = {
 625         .llseek         = ext4_dir_llseek,
 626         .read           = generic_read_dir,
 627         .readdir        = ext4_readdir,
 628         .unlocked_ioctl = ext4_ioctl,
 629 #ifdef CONFIG_COMPAT
 630         .compat_ioctl   = ext4_compat_ioctl,
 631 #endif
 632         .fsync          = ext4_sync_file,
 633         .release        = ext4_release_dir,
 634 };