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 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 - "
  88                         "offset=%u, inode=%u, rec_len=%d, name_len=%d",
  89                         dir->i_ino, error_msg, offset,
  90                         le32_to_cpu(de->inode),
  91                         rlen, de->name_len);
  92         return error_msg == NULL ? 1 : 0;
  93 }
  94
  95 static int ext4_readdir(struct file *filp,
  96                          void *dirent, filldir_t filldir)
  97 {
  98         int error = 0;
  99         unsigned int offset;
 100         int i, stored;
 101         struct ext4_dir_entry_2 *de;
 102         struct super_block *sb;
 103         int err;
 104         struct inode *inode = filp->f_path.dentry->d_inode;
 105         int ret = 0;
 106         int dir_has_error = 0;
 107
 108         sb = inode->i_sb;
 109
 110         if (EXT4_HAS_COMPAT_FEATURE(inode->i_sb,
 111                                     EXT4_FEATURE_COMPAT_DIR_INDEX) &&
 112             ((EXT4_I(inode)->i_flags & EXT4_INDEX_FL) ||
 113              ((inode->i_size >> sb->s_blocksize_bits) == 1))) {
 114                 err = ext4_dx_readdir(filp, dirent, filldir);
 115                 if (err != ERR_BAD_DX_DIR) {
 116                         ret = err;
 117                         goto out;
 118                 }
 119                 /*
 120                  * We don't set the inode dirty flag since it's not
 121                  * critical that it get flushed back to the disk.
 122                  */
 123                 EXT4_I(filp->f_path.dentry->d_inode)->i_flags &= ~EXT4_INDEX_FL;
 124         }
 125         stored = 0;
 126         offset = filp->f_pos & (sb->s_blocksize - 1);
 127
 128         while (!error && !stored && filp->f_pos < inode->i_size) {
 129                 ext4_lblk_t blk = filp->f_pos >> EXT4_BLOCK_SIZE_BITS(sb);
 130                 struct buffer_head map_bh;
 131                 struct buffer_head *bh = NULL;
 132
 133                 map_bh.b_state = 0;
 134                 err = ext4_get_blocks(NULL, inode, blk, 1, &map_bh, 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                                         sb->s_blocksize) < EXT4_DIR_REC_LEN(1))
 183                                         break;
 184                                 i += ext4_rec_len_from_disk(de->rec_len,
 185                                                             sb->s_blocksize);
 186                         }
 187                         offset = i;
 188                         filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1))
 189                                 | offset;
 190                         filp->f_version = inode->i_version;
 191                 }
 192
 193                 while (!error && filp->f_pos < inode->i_size
 194                        && offset < sb->s_blocksize) {
 195                         de = (struct ext4_dir_entry_2 *) (bh->b_data + offset);
 196                         if (!ext4_check_dir_entry("ext4_readdir", inode, de,
 197                                                   bh, offset)) {
 198                                 /*
 199                                  * On error, skip the f_pos to the next block
 200                                  */
 201                                 filp->f_pos = (filp->f_pos |
 202                                                 (sb->s_blocksize - 1)) + 1;
 203                                 brelse(bh);
 204                                 ret = stored;
 205                                 goto out;
 206                         }
 207                         offset += ext4_rec_len_from_disk(de->rec_len,
 208                                         sb->s_blocksize);
 209                         if (le32_to_cpu(de->inode)) {
 210                                 /* We might block in the next section
 211                                  * if the data destination is
 212                                  * currently swapped out.  So, use a
 213                                  * version stamp to detect whether or
 214                                  * not the directory has been modified
 215                                  * during the copy operation.
 216                                  */
 217                                 u64 version = filp->f_version;
 218
 219                                 error = filldir(dirent, de->name,
 220                                                 de->name_len,
 221                                                 filp->f_pos,
 222                                                 le32_to_cpu(de->inode),
 223                                                 get_dtype(sb, de->file_type));
 224                                 if (error)
 225                                         break;
 226                                 if (version != filp->f_version)
 227                                         goto revalidate;
 228                                 stored++;
 229                         }
 230                         filp->f_pos += ext4_rec_len_from_disk(de->rec_len,
 231                                                 sb->s_blocksize);
 232                 }
 233                 offset = 0;
 234                 brelse(bh);
 235         }
 236 out:
 237         return ret;
 238 }
 239
 240 /*
 241  * These functions convert from the major/minor hash to an f_pos
 242  * value.
 243  *
 244  * Currently we only use major hash numer.  This is unfortunate, but
 245  * on 32-bit machines, the same VFS interface is used for lseek and
 246  * llseek, so if we use the 64 bit offset, then the 32-bit versions of
 247  * lseek/telldir/seekdir will blow out spectacularly, and from within
 248  * the ext2 low-level routine, we don't know if we're being called by
 249  * a 64-bit version of the system call or the 32-bit version of the
 250  * system call.  Worse yet, NFSv2 only allows for a 32-bit readdir
 251  * cookie.  Sigh.
 252  */
 253 #define hash2pos(major, minor)  (major >> 1)
 254 #define pos2maj_hash(pos)       ((pos << 1) & 0xffffffff)
 255 #define pos2min_hash(pos)       (0)
 256
 257 /*
 258  * This structure holds the nodes of the red-black tree used to store
 259  * the directory entry in hash order.
 260  */
 261 struct fname {
 262         __u32           hash;
 263         __u32           minor_hash;
 264         struct rb_node  rb_hash;
 265         struct fname    *next;
 266         __u32           inode;
 267         __u8            name_len;
 268         __u8            file_type;
 269         char            name[0];
 270 };
 271
 272 /*
 273  * This functoin implements a non-recursive way of freeing all of the
 274  * nodes in the red-black tree.
 275  */
 276 static void free_rb_tree_fname(struct rb_root *root)
 277 {
 278         struct rb_node  *n = root->rb_node;
 279         struct rb_node  *parent;
 280         struct fname    *fname;
 281
 282         while (n) {
 283                 /* Do the node's children first */
 284                 if (n->rb_left) {
 285                         n = n->rb_left;
 286                         continue;
 287                 }
 288                 if (n->rb_right) {
 289                         n = n->rb_right;
 290                         continue;
 291                 }
 292                 /*
 293                  * The node has no children; free it, and then zero
 294                  * out parent's link to it.  Finally go to the
 295                  * beginning of the loop and try to free the parent
 296                  * node.
 297                  */
 298                 parent = rb_parent(n);
 299                 fname = rb_entry(n, struct fname, rb_hash);
 300                 while (fname) {
 301                         struct fname *old = fname;
 302                         fname = fname->next;
 303                         kfree(old);
 304                 }
 305                 if (!parent)
 306                         root->rb_node = NULL;
 307                 else if (parent->rb_left == n)
 308                         parent->rb_left = NULL;
 309                 else if (parent->rb_right == n)
 310                         parent->rb_right = NULL;
 311                 n = parent;
 312         }
 313 }
 314
 315
 316 static struct dir_private_info *ext4_htree_create_dir_info(loff_t pos)
 317 {
 318         struct dir_private_info *p;
 319
 320         p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL);
 321         if (!p)
 322                 return NULL;
 323         p->curr_hash = pos2maj_hash(pos);
 324         p->curr_minor_hash = pos2min_hash(pos);
 325         return p;
 326 }
 327
 328 void ext4_htree_free_dir_info(struct dir_private_info *p)
 329 {
 330         free_rb_tree_fname(&p->root);
 331         kfree(p);
 332 }
 333
 334 /*
 335  * Given a directory entry, enter it into the fname rb tree.
 336  */
 337 int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,
 338                              __u32 minor_hash,
 339                              struct ext4_dir_entry_2 *dirent)
 340 {
 341         struct rb_node **p, *parent = NULL;
 342         struct fname *fname, *new_fn;
 343         struct dir_private_info *info;
 344         int len;
 345
 346         info = (struct dir_private_info *) dir_file->private_data;
 347         p = &info->root.rb_node;
 348
 349         /* Create and allocate the fname structure */
 350         len = sizeof(struct fname) + dirent->name_len + 1;
 351         new_fn = kzalloc(len, GFP_KERNEL);
 352         if (!new_fn)
 353                 return -ENOMEM;
 354         new_fn->hash = hash;
 355         new_fn->minor_hash = minor_hash;
 356         new_fn->inode = le32_to_cpu(dirent->inode);
 357         new_fn->name_len = dirent->name_len;
 358         new_fn->file_type = dirent->file_type;
 359         memcpy(new_fn->name, dirent->name, dirent->name_len);
 360         new_fn->name[dirent->name_len] = 0;
 361
 362         while (*p) {
 363                 parent = *p;
 364                 fname = rb_entry(parent, struct fname, rb_hash);
 365
 366                 /*
 367                  * If the hash and minor hash match up, then we put
 368                  * them on a linked list.  This rarely happens...
 369                  */
 370                 if ((new_fn->hash == fname->hash) &&
 371                     (new_fn->minor_hash == fname->minor_hash)) {
 372                         new_fn->next = fname->next;
 373                         fname->next = new_fn;
 374                         return 0;
 375                 }
 376
 377                 if (new_fn->hash < fname->hash)
 378                         p = &(*p)->rb_left;
 379                 else if (new_fn->hash > fname->hash)
 380                         p = &(*p)->rb_right;
 381                 else if (new_fn->minor_hash < fname->minor_hash)
 382                         p = &(*p)->rb_left;
 383                 else /* if (new_fn->minor_hash > fname->minor_hash) */
 384                         p = &(*p)->rb_right;
 385         }
 386
 387         rb_link_node(&new_fn->rb_hash, parent, p);
 388         rb_insert_color(&new_fn->rb_hash, &info->root);
 389         return 0;
 390 }
 391
 392
 393
 394 /*
 395  * This is a helper function for ext4_dx_readdir.  It calls filldir
 396  * for all entres on the fname linked list.  (Normally there is only
 397  * one entry on the linked list, unless there are 62 bit hash collisions.)
 398  */
 399 static int call_filldir(struct file *filp, void *dirent,
 400                         filldir_t filldir, struct fname *fname)
 401 {
 402         struct dir_private_info *info = filp->private_data;
 403         loff_t  curr_pos;
 404         struct inode *inode = filp->f_path.dentry->d_inode;
 405         struct super_block *sb;
 406         int error;
 407
 408         sb = inode->i_sb;
 409
 410         if (!fname) {
 411                 printk(KERN_ERR "EXT4-fs: call_filldir: called with "
 412                        "null fname?!?\n");
 413                 return 0;
 414         }
 415         curr_pos = hash2pos(fname->hash, fname->minor_hash);
 416         while (fname) {
 417                 error = filldir(dirent, fname->name,
 418                                 fname->name_len, curr_pos,
 419                                 fname->inode,
 420                                 get_dtype(sb, fname->file_type));
 421                 if (error) {
 422                         filp->f_pos = curr_pos;
 423                         info->extra_fname = fname;
 424                         return error;
 425                 }
 426                 fname = fname->next;
 427         }
 428         return 0;
 429 }
 430
 431 static int ext4_dx_readdir(struct file *filp,
 432                          void *dirent, filldir_t filldir)
 433 {
 434         struct dir_private_info *info = filp->private_data;
 435         struct inode *inode = filp->f_path.dentry->d_inode;
 436         struct fname *fname;
 437         int     ret;
 438
 439         if (!info) {
 440                 info = ext4_htree_create_dir_info(filp->f_pos);
 441                 if (!info)
 442                         return -ENOMEM;
 443                 filp->private_data = info;
 444         }
 445
 446         if (filp->f_pos == EXT4_HTREE_EOF)
 447                 return 0;       /* EOF */
 448
 449         /* Some one has messed with f_pos; reset the world */
 450         if (info->last_pos != filp->f_pos) {
 451                 free_rb_tree_fname(&info->root);
 452                 info->curr_node = NULL;
 453                 info->extra_fname = NULL;
 454                 info->curr_hash = pos2maj_hash(filp->f_pos);
 455                 info->curr_minor_hash = pos2min_hash(filp->f_pos);
 456         }
 457
 458         /*
 459          * If there are any leftover names on the hash collision
 460          * chain, return them first.
 461          */
 462         if (info->extra_fname) {
 463                 if (call_filldir(filp, dirent, filldir, info->extra_fname))
 464                         goto finished;
 465                 info->extra_fname = NULL;
 466                 goto next_node;
 467         } else if (!info->curr_node)
 468                 info->curr_node = rb_first(&info->root);
 469
 470         while (1) {
 471                 /*
 472                  * Fill the rbtree if we have no more entries,
 473                  * or the inode has changed since we last read in the
 474                  * cached entries.
 475                  */
 476                 if ((!info->curr_node) ||
 477                     (filp->f_version != inode->i_version)) {
 478                         info->curr_node = NULL;
 479                         free_rb_tree_fname(&info->root);
 480                         filp->f_version = inode->i_version;
 481                         ret = ext4_htree_fill_tree(filp, info->curr_hash,
 482                                                    info->curr_minor_hash,
 483                                                    &info->next_hash);
 484                         if (ret < 0)
 485                                 return ret;
 486                         if (ret == 0) {
 487                                 filp->f_pos = EXT4_HTREE_EOF;
 488                                 break;
 489                         }
 490                         info->curr_node = rb_first(&info->root);
 491                 }
 492
 493                 fname = rb_entry(info->curr_node, struct fname, rb_hash);
 494                 info->curr_hash = fname->hash;
 495                 info->curr_minor_hash = fname->minor_hash;
 496                 if (call_filldir(filp, dirent, filldir, fname))
 497                         break;
 498         next_node:
 499                 info->curr_node = rb_next(info->curr_node);
 500                 if (info->curr_node) {
 501                         fname = rb_entry(info->curr_node, struct fname,
 502                                          rb_hash);
 503                         info->curr_hash = fname->hash;
 504                         info->curr_minor_hash = fname->minor_hash;
 505                 } else {
 506                         if (info->next_hash == ~0) {
 507                                 filp->f_pos = EXT4_HTREE_EOF;
 508                                 break;
 509                         }
 510                         info->curr_hash = info->next_hash;
 511                         info->curr_minor_hash = 0;
 512                 }
 513         }
 514 finished:
 515         info->last_pos = filp->f_pos;
 516         return 0;
 517 }
 518
 519 static int ext4_release_dir(struct inode *inode, struct file *filp)
 520 {
 521         if (filp->private_data)
 522                 ext4_htree_free_dir_info(filp->private_data);
 523
 524         return 0;
 525 }