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         = ext4_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, unsigned int line,
  65                            struct inode *dir,
  66                            struct ext4_dir_entry_2 *de,
  67                            struct buffer_head *bh,
  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 (rlen < EXT4_DIR_REC_LEN(1))
  75                 error_msg = "rec_len is smaller than minimal";
  76         else if (rlen % 4 != 0)
  77                 error_msg = "rec_len % 4 != 0";
  78         else if (rlen < EXT4_DIR_REC_LEN(de->name_len))
  79                 error_msg = "rec_len is too small for name_len";
  80         else if (((char *) de - bh->b_data) + rlen > dir->i_sb->s_blocksize)
  81                 error_msg = "directory entry across blocks";
  82         else if (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
  86         if (error_msg != NULL)
  87                 ext4_error_inode(dir, function, line, bh->b_blocknr,
  88                         "bad entry in directory: %s - "
  89                         "offset=%u(%u), inode=%u, rec_len=%d, name_len=%d",
  90                         error_msg, (unsigned) (offset%bh->b_size), offset,
  91                         le32_to_cpu(de->inode),
  92                         rlen, de->name_len);
  93         return error_msg == NULL ? 1 : 0;
  94 }
  95
  96 static int ext4_readdir(struct file *filp,
  97                          void *dirent, filldir_t filldir)
  98 {
  99         int error = 0;
 100         unsigned int offset;
 101         int i, stored;
 102         struct ext4_dir_entry_2 *de;
 103         struct super_block *sb;
 104         int err;
 105         struct inode *inode = filp->f_path.dentry->d_inode;
 106         int ret = 0;
 107         int dir_has_error = 0;
 108
 109         sb = inode->i_sb;
 110
 111         if (EXT4_HAS_COMPAT_FEATURE(inode->i_sb,
 112                                     EXT4_FEATURE_COMPAT_DIR_INDEX) &&
 113             ((ext4_test_inode_flag(inode, EXT4_INODE_INDEX)) ||
 114              ((inode->i_size >> sb->s_blocksize_bits) == 1))) {
 115                 err = ext4_dx_readdir(filp, dirent, filldir);
 116                 if (err != ERR_BAD_DX_DIR) {
 117                         ret = err;
 118                         goto out;
 119                 }
 120                 /*
 121                  * We don't set the inode dirty flag since it's not
 122                  * critical that it get flushed back to the disk.
 123                  */
 124                 ext4_clear_inode_flag(filp->f_path.dentry->d_inode,
 125                                       EXT4_INODE_INDEX);
 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                 struct ext4_map_blocks map;
 132                 struct buffer_head *bh = NULL;
 133
 134                 map.m_lblk = filp->f_pos >> EXT4_BLOCK_SIZE_BITS(sb);
 135                 map.m_len = 1;
 136                 err = ext4_map_blocks(NULL, inode, &map, 0);
 137                 if (err > 0) {
 138                         pgoff_t index = map.m_pblk >>
 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, map.m_lblk, 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_INODE(inode, "directory "
 156                                            "contains a hole at offset %Lu",
 157                                            (unsigned long long) filp->f_pos);
 158                                 dir_has_error = 1;
 159                         }
 160                         /* corrupt size?  Maybe no more blocks to read */
 161                         if (filp->f_pos > inode->i_blocks << 9)
 162                                 break;
 163                         filp->f_pos += sb->s_blocksize - offset;
 164                         continue;
 165                 }
 166
 167 revalidate:
 168                 /* If the dir block has changed since the last call to
 169                  * readdir(2), then we might be pointing to an invalid
 170                  * dirent right now.  Scan from the start of the block
 171                  * to make sure. */
 172                 if (filp->f_version != inode->i_version) {
 173                         for (i = 0; i < sb->s_blocksize && i < offset; ) {
 174                                 de = (struct ext4_dir_entry_2 *)
 175                                         (bh->b_data + i);
 176                                 /* It's too expensive to do a full
 177                                  * dirent test each time round this
 178                                  * loop, but we do have to test at
 179                                  * least that it is non-zero.  A
 180                                  * failure will be detected in the
 181                                  * dirent test below. */
 182                                 if (ext4_rec_len_from_disk(de->rec_len,
 183                                         sb->s_blocksize) < EXT4_DIR_REC_LEN(1))
 184                                         break;
 185                                 i += ext4_rec_len_from_disk(de->rec_len,
 186                                                             sb->s_blocksize);
 187                         }
 188                         offset = i;
 189                         filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1))
 190                                 | offset;
 191                         filp->f_version = inode->i_version;
 192                 }
 193
 194                 while (!error && filp->f_pos < inode->i_size
 195                        && offset < sb->s_blocksize) {
 196                         de = (struct ext4_dir_entry_2 *) (bh->b_data + offset);
 197                         if (!ext4_check_dir_entry(inode, de,
 198                                                   bh, offset)) {
 199                                 /*
 200                                  * On error, skip the f_pos to the next block
 201                                  */
 202                                 filp->f_pos = (filp->f_pos |
 203                                                 (sb->s_blocksize - 1)) + 1;
 204                                 brelse(bh);
 205                                 ret = stored;
 206                                 goto out;
 207                         }
 208                         offset += ext4_rec_len_from_disk(de->rec_len,
 209                                         sb->s_blocksize);
 210                         if (le32_to_cpu(de->inode)) {
 211                                 /* We might block in the next section
 212                                  * if the data destination is
 213                                  * currently swapped out.  So, use a
 214                                  * version stamp to detect whether or
 215                                  * not the directory has been modified
 216                                  * during the copy operation.
 217                                  */
 218                                 u64 version = filp->f_version;
 219
 220                                 error = filldir(dirent, de->name,
 221                                                 de->name_len,
 222                                                 filp->f_pos,
 223                                                 le32_to_cpu(de->inode),
 224                                                 get_dtype(sb, de->file_type));
 225                                 if (error)
 226                                         break;
 227                                 if (version != filp->f_version)
 228                                         goto revalidate;
 229                                 stored++;
 230                         }
 231                         filp->f_pos += ext4_rec_len_from_disk(de->rec_len,
 232                                                 sb->s_blocksize);
 233                 }
 234                 offset = 0;
 235                 brelse(bh);
 236         }
 237 out:
 238         return ret;
 239 }
 240
 241 /*
 242  * These functions convert from the major/minor hash to an f_pos
 243  * value.
 244  *
 245  * Currently we only use major hash numer.  This is unfortunate, but
 246  * on 32-bit machines, the same VFS interface is used for lseek and
 247  * llseek, so if we use the 64 bit offset, then the 32-bit versions of
 248  * lseek/telldir/seekdir will blow out spectacularly, and from within
 249  * the ext2 low-level routine, we don't know if we're being called by
 250  * a 64-bit version of the system call or the 32-bit version of the
 251  * system call.  Worse yet, NFSv2 only allows for a 32-bit readdir
 252  * cookie.  Sigh.
 253  */
 254 #define hash2pos(major, minor)  (major >> 1)
 255 #define pos2maj_hash(pos)       ((pos << 1) & 0xffffffff)
 256 #define pos2min_hash(pos)       (0)
 257
 258 /*
 259  * This structure holds the nodes of the red-black tree used to store
 260  * the directory entry in hash order.
 261  */
 262 struct fname {
 263         __u32           hash;
 264         __u32           minor_hash;
 265         struct rb_node  rb_hash;
 266         struct fname    *next;
 267         __u32           inode;
 268         __u8            name_len;
 269         __u8            file_type;
 270         char            name[0];
 271 };
 272
 273 /*
 274  * This functoin implements a non-recursive way of freeing all of the
 275  * nodes in the red-black tree.
 276  */
 277 static void free_rb_tree_fname(struct rb_root *root)
 278 {
 279         struct rb_node  *n = root->rb_node;
 280         struct rb_node  *parent;
 281         struct fname    *fname;
 282
 283         while (n) {
 284                 /* Do the node's children first */
 285                 if (n->rb_left) {
 286                         n = n->rb_left;
 287                         continue;
 288                 }
 289                 if (n->rb_right) {
 290                         n = n->rb_right;
 291                         continue;
 292                 }
 293                 /*
 294                  * The node has no children; free it, and then zero
 295                  * out parent's link to it.  Finally go to the
 296                  * beginning of the loop and try to free the parent
 297                  * node.
 298                  */
 299                 parent = rb_parent(n);
 300                 fname = rb_entry(n, struct fname, rb_hash);
 301                 while (fname) {
 302                         struct fname *old = fname;
 303                         fname = fname->next;
 304                         kfree(old);
 305                 }
 306                 if (!parent)
 307                         *root = RB_ROOT;
 308                 else if (parent->rb_left == n)
 309                         parent->rb_left = NULL;
 310                 else if (parent->rb_right == n)
 311                         parent->rb_right = NULL;
 312                 n = parent;
 313         }
 314 }
 315
 316
 317 static struct dir_private_info *ext4_htree_create_dir_info(loff_t pos)
 318 {
 319         struct dir_private_info *p;
 320
 321         p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL);
 322         if (!p)
 323                 return NULL;
 324         p->curr_hash = pos2maj_hash(pos);
 325         p->curr_minor_hash = pos2min_hash(pos);
 326         return p;
 327 }
 328
 329 void ext4_htree_free_dir_info(struct dir_private_info *p)
 330 {
 331         free_rb_tree_fname(&p->root);
 332         kfree(p);
 333 }
 334
 335 /*
 336  * Given a directory entry, enter it into the fname rb tree.
 337  */
 338 int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,
 339                              __u32 minor_hash,
 340                              struct ext4_dir_entry_2 *dirent)
 341 {
 342         struct rb_node **p, *parent = NULL;
 343         struct fname *fname, *new_fn;
 344         struct dir_private_info *info;
 345         int len;
 346
 347         info = dir_file->private_data;
 348         p = &info->root.rb_node;
 349
 350         /* Create and allocate the fname structure */
 351         len = sizeof(struct fname) + dirent->name_len + 1;
 352         new_fn = kzalloc(len, GFP_KERNEL);
 353         if (!new_fn)
 354                 return -ENOMEM;
 355         new_fn->hash = hash;
 356         new_fn->minor_hash = minor_hash;
 357         new_fn->inode = le32_to_cpu(dirent->inode);
 358         new_fn->name_len = dirent->name_len;
 359         new_fn->file_type = dirent->file_type;
 360         memcpy(new_fn->name, dirent->name, dirent->name_len);
 361         new_fn->name[dirent->name_len] = 0;
 362
 363         while (*p) {
 364                 parent = *p;
 365                 fname = rb_entry(parent, struct fname, rb_hash);
 366
 367                 /*
 368                  * If the hash and minor hash match up, then we put
 369                  * them on a linked list.  This rarely happens...
 370                  */
 371                 if ((new_fn->hash == fname->hash) &&
 372                     (new_fn->minor_hash == fname->minor_hash)) {
 373                         new_fn->next = fname->next;
 374                         fname->next = new_fn;
 375                         return 0;
 376                 }
 377
 378                 if (new_fn->hash < fname->hash)
 379                         p = &(*p)->rb_left;
 380                 else if (new_fn->hash > fname->hash)
 381                         p = &(*p)->rb_right;
 382                 else if (new_fn->minor_hash < fname->minor_hash)
 383                         p = &(*p)->rb_left;
 384                 else /* if (new_fn->minor_hash > fname->minor_hash) */
 385                         p = &(*p)->rb_right;
 386         }
 387
 388         rb_link_node(&new_fn->rb_hash, parent, p);
 389         rb_insert_color(&new_fn->rb_hash, &info->root);
 390         return 0;
 391 }
 392
 393
 394
 395 /*
 396  * This is a helper function for ext4_dx_readdir.  It calls filldir
 397  * for all entres on the fname linked list.  (Normally there is only
 398  * one entry on the linked list, unless there are 62 bit hash collisions.)
 399  */
 400 static int call_filldir(struct file *filp, void *dirent,
 401                         filldir_t filldir, struct fname *fname)
 402 {
 403         struct dir_private_info *info = filp->private_data;
 404         loff_t  curr_pos;
 405         struct inode *inode = filp->f_path.dentry->d_inode;
 406         struct super_block *sb;
 407         int error;
 408
 409         sb = inode->i_sb;
 410
 411         if (!fname) {
 412                 printk(KERN_ERR "EXT4-fs: call_filldir: called with "
 413                        "null fname?!?\n");
 414                 return 0;
 415         }
 416         curr_pos = hash2pos(fname->hash, fname->minor_hash);
 417         while (fname) {
 418                 error = filldir(dirent, fname->name,
 419                                 fname->name_len, curr_pos,
 420                                 fname->inode,
 421                                 get_dtype(sb, fname->file_type));
 422                 if (error) {
 423                         filp->f_pos = curr_pos;
 424                         info->extra_fname = fname;
 425                         return error;
 426                 }
 427                 fname = fname->next;
 428         }
 429         return 0;
 430 }
 431
 432 static int ext4_dx_readdir(struct file *filp,
 433                          void *dirent, filldir_t filldir)
 434 {
 435         struct dir_private_info *info = filp->private_data;
 436         struct inode *inode = filp->f_path.dentry->d_inode;
 437         struct fname *fname;
 438         int     ret;
 439
 440         if (!info) {
 441                 info = ext4_htree_create_dir_info(filp->f_pos);
 442                 if (!info)
 443                         return -ENOMEM;
 444                 filp->private_data = info;
 445         }
 446
 447         if (filp->f_pos == EXT4_HTREE_EOF)
 448                 return 0;       /* EOF */
 449
 450         /* Some one has messed with f_pos; reset the world */
 451         if (info->last_pos != filp->f_pos) {
 452                 free_rb_tree_fname(&info->root);
 453                 info->curr_node = NULL;
 454                 info->extra_fname = NULL;
 455                 info->curr_hash = pos2maj_hash(filp->f_pos);
 456                 info->curr_minor_hash = pos2min_hash(filp->f_pos);
 457         }
 458
 459         /*
 460          * If there are any leftover names on the hash collision
 461          * chain, return them first.
 462          */
 463         if (info->extra_fname) {
 464                 if (call_filldir(filp, dirent, filldir, info->extra_fname))
 465                         goto finished;
 466                 info->extra_fname = NULL;
 467                 goto next_node;
 468         } else if (!info->curr_node)
 469                 info->curr_node = rb_first(&info->root);
 470
 471         while (1) {
 472                 /*
 473                  * Fill the rbtree if we have no more entries,
 474                  * or the inode has changed since we last read in the
 475                  * cached entries.
 476                  */
 477                 if ((!info->curr_node) ||
 478                     (filp->f_version != inode->i_version)) {
 479                         info->curr_node = NULL;
 480                         free_rb_tree_fname(&info->root);
 481                         filp->f_version = inode->i_version;
 482                         ret = ext4_htree_fill_tree(filp, info->curr_hash,
 483                                                    info->curr_minor_hash,
 484                                                    &info->next_hash);
 485                         if (ret < 0)
 486                                 return ret;
 487                         if (ret == 0) {
 488                                 filp->f_pos = EXT4_HTREE_EOF;
 489                                 break;
 490                         }
 491                         info->curr_node = rb_first(&info->root);
 492                 }
 493
 494                 fname = rb_entry(info->curr_node, struct fname, rb_hash);
 495                 info->curr_hash = fname->hash;
 496                 info->curr_minor_hash = fname->minor_hash;
 497                 if (call_filldir(filp, dirent, filldir, fname))
 498                         break;
 499         next_node:
 500                 info->curr_node = rb_next(info->curr_node);
 501                 if (info->curr_node) {
 502                         fname = rb_entry(info->curr_node, struct fname,
 503                                          rb_hash);
 504                         info->curr_hash = fname->hash;
 505                         info->curr_minor_hash = fname->minor_hash;
 506                 } else {
 507                         if (info->next_hash == ~0) {
 508                                 filp->f_pos = EXT4_HTREE_EOF;
 509                                 break;
 510                         }
 511                         info->curr_hash = info->next_hash;
 512                         info->curr_minor_hash = 0;
 513                 }
 514         }
 515 finished:
 516         info->last_pos = filp->f_pos;
 517         return 0;
 518 }
 519
 520 static int ext4_release_dir(struct inode *inode, struct file *filp)
 521 {
 522         if (filp->private_data)
 523                 ext4_htree_free_dir_info(filp->private_data);
 524
 525         return 0;
 526 }