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dir.c
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1 /*
2  * linux/fs/ext3/dir.c
3  *
4  * Copyright (C) 1992, 1993, 1994, 1995
5  * Remy Card ([email protected])
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  * ext3 directory handling functions
16  *
17  * Big-endian to little-endian byte-swapping/bitmaps by
18  * David S. Miller ([email protected]), 1995
19  *
20  * Hash Tree Directory indexing (c) 2001 Daniel Phillips
21  *
22  */
23 
24 #include <linux/compat.h>
25 #include "ext3.h"
26 
27 static unsigned char ext3_filetype_table[] = {
29 };
30 
31 static int ext3_dx_readdir(struct file * filp,
32  void * dirent, filldir_t filldir);
33 
34 static unsigned char get_dtype(struct super_block *sb, int filetype)
35 {
37  (filetype >= EXT3_FT_MAX))
38  return DT_UNKNOWN;
39 
40  return (ext3_filetype_table[filetype]);
41 }
42 
50 static int is_dx_dir(struct inode *inode)
51 {
52  struct super_block *sb = inode->i_sb;
53 
54  if (EXT3_HAS_COMPAT_FEATURE(inode->i_sb,
56  ((EXT3_I(inode)->i_flags & EXT3_INDEX_FL) ||
57  ((inode->i_size >> sb->s_blocksize_bits) == 1)))
58  return 1;
59 
60  return 0;
61 }
62 
63 int ext3_check_dir_entry (const char * function, struct inode * dir,
64  struct ext3_dir_entry_2 * de,
65  struct buffer_head * bh,
66  unsigned long offset)
67 {
68  const char * error_msg = NULL;
69  const int rlen = ext3_rec_len_from_disk(de->rec_len);
70 
71  if (unlikely(rlen < EXT3_DIR_REC_LEN(1)))
72  error_msg = "rec_len is smaller than minimal";
73  else if (unlikely(rlen % 4 != 0))
74  error_msg = "rec_len % 4 != 0";
75  else if (unlikely(rlen < EXT3_DIR_REC_LEN(de->name_len)))
76  error_msg = "rec_len is too small for name_len";
77  else if (unlikely((((char *) de - bh->b_data) + rlen > dir->i_sb->s_blocksize)))
78  error_msg = "directory entry across blocks";
79  else if (unlikely(le32_to_cpu(de->inode) >
80  le32_to_cpu(EXT3_SB(dir->i_sb)->s_es->s_inodes_count)))
81  error_msg = "inode out of bounds";
82 
83  if (unlikely(error_msg != NULL))
84  ext3_error (dir->i_sb, function,
85  "bad entry in directory #%lu: %s - "
86  "offset=%lu, inode=%lu, rec_len=%d, name_len=%d",
87  dir->i_ino, error_msg, offset,
88  (unsigned long) le32_to_cpu(de->inode),
89  rlen, de->name_len);
90 
91  return error_msg == NULL ? 1 : 0;
92 }
93 
94 static int ext3_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 ext3_dir_entry_2 *de;
101  int err;
102  struct inode *inode = filp->f_path.dentry->d_inode;
103  struct super_block *sb = inode->i_sb;
104  int ret = 0;
105  int dir_has_error = 0;
106 
107  if (is_dx_dir(inode)) {
108  err = ext3_dx_readdir(filp, dirent, filldir);
109  if (err != ERR_BAD_DX_DIR) {
110  ret = err;
111  goto out;
112  }
113  /*
114  * We don't set the inode dirty flag since it's not
115  * critical that it get flushed back to the disk.
116  */
117  EXT3_I(filp->f_path.dentry->d_inode)->i_flags &= ~EXT3_INDEX_FL;
118  }
119  stored = 0;
120  offset = filp->f_pos & (sb->s_blocksize - 1);
121 
122  while (!error && !stored && filp->f_pos < inode->i_size) {
123  unsigned long blk = filp->f_pos >> EXT3_BLOCK_SIZE_BITS(sb);
124  struct buffer_head map_bh;
125  struct buffer_head *bh = NULL;
126 
127  map_bh.b_state = 0;
128  err = ext3_get_blocks_handle(NULL, inode, blk, 1, &map_bh, 0);
129  if (err > 0) {
130  pgoff_t index = map_bh.b_blocknr >>
131  (PAGE_CACHE_SHIFT - inode->i_blkbits);
132  if (!ra_has_index(&filp->f_ra, index))
134  sb->s_bdev->bd_inode->i_mapping,
135  &filp->f_ra, filp,
136  index, 1);
137  filp->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT;
138  bh = ext3_bread(NULL, inode, blk, 0, &err);
139  }
140 
141  /*
142  * We ignore I/O errors on directories so users have a chance
143  * of recovering data when there's a bad sector
144  */
145  if (!bh) {
146  if (!dir_has_error) {
147  ext3_error(sb, __func__, "directory #%lu "
148  "contains a hole at offset %lld",
149  inode->i_ino, filp->f_pos);
150  dir_has_error = 1;
151  }
152  /* corrupt size? Maybe no more blocks to read */
153  if (filp->f_pos > inode->i_blocks << 9)
154  break;
155  filp->f_pos += sb->s_blocksize - offset;
156  continue;
157  }
158 
159 revalidate:
160  /* If the dir block has changed since the last call to
161  * readdir(2), then we might be pointing to an invalid
162  * dirent right now. Scan from the start of the block
163  * to make sure. */
164  if (filp->f_version != inode->i_version) {
165  for (i = 0; i < sb->s_blocksize && i < offset; ) {
166  de = (struct ext3_dir_entry_2 *)
167  (bh->b_data + i);
168  /* It's too expensive to do a full
169  * dirent test each time round this
170  * loop, but we do have to test at
171  * least that it is non-zero. A
172  * failure will be detected in the
173  * dirent test below. */
174  if (ext3_rec_len_from_disk(de->rec_len) <
175  EXT3_DIR_REC_LEN(1))
176  break;
177  i += ext3_rec_len_from_disk(de->rec_len);
178  }
179  offset = i;
180  filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1))
181  | offset;
182  filp->f_version = inode->i_version;
183  }
184 
185  while (!error && filp->f_pos < inode->i_size
187  de = (struct ext3_dir_entry_2 *) (bh->b_data + offset);
188  if (!ext3_check_dir_entry ("ext3_readdir", inode, de,
189  bh, offset)) {
190  /* On error, skip the f_pos to the
191  next block. */
192  filp->f_pos = (filp->f_pos |
193  (sb->s_blocksize - 1)) + 1;
194  brelse (bh);
195  ret = stored;
196  goto out;
197  }
198  offset += ext3_rec_len_from_disk(de->rec_len);
199  if (le32_to_cpu(de->inode)) {
200  /* We might block in the next section
201  * if the data destination is
202  * currently swapped out. So, use a
203  * version stamp to detect whether or
204  * not the directory has been modified
205  * during the copy operation.
206  */
207  u64 version = filp->f_version;
208 
209  error = filldir(dirent, de->name,
210  de->name_len,
211  filp->f_pos,
212  le32_to_cpu(de->inode),
213  get_dtype(sb, de->file_type));
214  if (error)
215  break;
216  if (version != filp->f_version)
217  goto revalidate;
218  stored ++;
219  }
220  filp->f_pos += ext3_rec_len_from_disk(de->rec_len);
221  }
222  offset = 0;
223  brelse (bh);
224  }
225 out:
226  return ret;
227 }
228 
229 static inline int is_32bit_api(void)
230 {
231 #ifdef CONFIG_COMPAT
232  return is_compat_task();
233 #else
234  return (BITS_PER_LONG == 32);
235 #endif
236 }
237 
238 /*
239  * These functions convert from the major/minor hash to an f_pos
240  * value for dx directories
241  *
242  * Upper layer (for example NFS) should specify FMODE_32BITHASH or
243  * FMODE_64BITHASH explicitly. On the other hand, we allow ext3 to be mounted
244  * directly on both 32-bit and 64-bit nodes, under such case, neither
245  * FMODE_32BITHASH nor FMODE_64BITHASH is specified.
246  */
247 static inline loff_t hash2pos(struct file *filp, __u32 major, __u32 minor)
248 {
249  if ((filp->f_mode & FMODE_32BITHASH) ||
250  (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
251  return major >> 1;
252  else
253  return ((__u64)(major >> 1) << 32) | (__u64)minor;
254 }
255 
256 static inline __u32 pos2maj_hash(struct file *filp, loff_t pos)
257 {
258  if ((filp->f_mode & FMODE_32BITHASH) ||
259  (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
260  return (pos << 1) & 0xffffffff;
261  else
262  return ((pos >> 32) << 1) & 0xffffffff;
263 }
264 
265 static inline __u32 pos2min_hash(struct file *filp, loff_t pos)
266 {
267  if ((filp->f_mode & FMODE_32BITHASH) ||
268  (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
269  return 0;
270  else
271  return pos & 0xffffffff;
272 }
273 
274 /*
275  * Return 32- or 64-bit end-of-file for dx directories
276  */
277 static inline loff_t ext3_get_htree_eof(struct file *filp)
278 {
279  if ((filp->f_mode & FMODE_32BITHASH) ||
280  (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
281  return EXT3_HTREE_EOF_32BIT;
282  else
283  return EXT3_HTREE_EOF_64BIT;
284 }
285 
286 
287 /*
288  * ext3_dir_llseek() calls generic_file_llseek[_size]() to handle both
289  * non-htree and htree directories, where the "offset" is in terms
290  * of the filename hash value instead of the byte offset.
291  *
292  * Because we may return a 64-bit hash that is well beyond s_maxbytes,
293  * we need to pass the max hash as the maximum allowable offset in
294  * the htree directory case.
295  *
296  * NOTE: offsets obtained *before* ext3_set_inode_flag(dir, EXT3_INODE_INDEX)
297  * will be invalid once the directory was converted into a dx directory
298  */
299 loff_t ext3_dir_llseek(struct file *file, loff_t offset, int origin)
300 {
301  struct inode *inode = file->f_mapping->host;
302  int dx_dir = is_dx_dir(inode);
303  loff_t htree_max = ext3_get_htree_eof(file);
304 
305  if (likely(dx_dir))
306  return generic_file_llseek_size(file, offset, origin,
307  htree_max, htree_max);
308  else
309  return generic_file_llseek(file, offset, origin);
310 }
311 
312 /*
313  * This structure holds the nodes of the red-black tree used to store
314  * the directory entry in hash order.
315  */
316 struct fname {
319  struct rb_node rb_hash;
320  struct fname *next;
324  char name[0];
325 };
326 
327 /*
328  * This functoin implements a non-recursive way of freeing all of the
329  * nodes in the red-black tree.
330  */
331 static void free_rb_tree_fname(struct rb_root *root)
332 {
333  struct rb_node *n = root->rb_node;
334  struct rb_node *parent;
335  struct fname *fname;
336 
337  while (n) {
338  /* Do the node's children first */
339  if (n->rb_left) {
340  n = n->rb_left;
341  continue;
342  }
343  if (n->rb_right) {
344  n = n->rb_right;
345  continue;
346  }
347  /*
348  * The node has no children; free it, and then zero
349  * out parent's link to it. Finally go to the
350  * beginning of the loop and try to free the parent
351  * node.
352  */
353  parent = rb_parent(n);
354  fname = rb_entry(n, struct fname, rb_hash);
355  while (fname) {
356  struct fname * old = fname;
357  fname = fname->next;
358  kfree (old);
359  }
360  if (!parent)
361  *root = RB_ROOT;
362  else if (parent->rb_left == n)
363  parent->rb_left = NULL;
364  else if (parent->rb_right == n)
365  parent->rb_right = NULL;
366  n = parent;
367  }
368 }
369 
370 
371 static struct dir_private_info *ext3_htree_create_dir_info(struct file *filp,
372  loff_t pos)
373 {
374  struct dir_private_info *p;
375 
376  p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL);
377  if (!p)
378  return NULL;
379  p->curr_hash = pos2maj_hash(filp, pos);
380  p->curr_minor_hash = pos2min_hash(filp, pos);
381  return p;
382 }
383 
385 {
386  free_rb_tree_fname(&p->root);
387  kfree(p);
388 }
389 
390 /*
391  * Given a directory entry, enter it into the fname rb tree.
392  */
393 int ext3_htree_store_dirent(struct file *dir_file, __u32 hash,
394  __u32 minor_hash,
395  struct ext3_dir_entry_2 *dirent)
396 {
397  struct rb_node **p, *parent = NULL;
398  struct fname * fname, *new_fn;
399  struct dir_private_info *info;
400  int len;
401 
402  info = (struct dir_private_info *) dir_file->private_data;
403  p = &info->root.rb_node;
404 
405  /* Create and allocate the fname structure */
406  len = sizeof(struct fname) + dirent->name_len + 1;
407  new_fn = kzalloc(len, GFP_KERNEL);
408  if (!new_fn)
409  return -ENOMEM;
410  new_fn->hash = hash;
411  new_fn->minor_hash = minor_hash;
412  new_fn->inode = le32_to_cpu(dirent->inode);
413  new_fn->name_len = dirent->name_len;
414  new_fn->file_type = dirent->file_type;
415  memcpy(new_fn->name, dirent->name, dirent->name_len);
416  new_fn->name[dirent->name_len] = 0;
417 
418  while (*p) {
419  parent = *p;
420  fname = rb_entry(parent, struct fname, rb_hash);
421 
422  /*
423  * If the hash and minor hash match up, then we put
424  * them on a linked list. This rarely happens...
425  */
426  if ((new_fn->hash == fname->hash) &&
427  (new_fn->minor_hash == fname->minor_hash)) {
428  new_fn->next = fname->next;
429  fname->next = new_fn;
430  return 0;
431  }
432 
433  if (new_fn->hash < fname->hash)
434  p = &(*p)->rb_left;
435  else if (new_fn->hash > fname->hash)
436  p = &(*p)->rb_right;
437  else if (new_fn->minor_hash < fname->minor_hash)
438  p = &(*p)->rb_left;
439  else /* if (new_fn->minor_hash > fname->minor_hash) */
440  p = &(*p)->rb_right;
441  }
442 
443  rb_link_node(&new_fn->rb_hash, parent, p);
444  rb_insert_color(&new_fn->rb_hash, &info->root);
445  return 0;
446 }
447 
448 
449 
450 /*
451  * This is a helper function for ext3_dx_readdir. It calls filldir
452  * for all entres on the fname linked list. (Normally there is only
453  * one entry on the linked list, unless there are 62 bit hash collisions.)
454  */
455 static int call_filldir(struct file * filp, void * dirent,
456  filldir_t filldir, struct fname *fname)
457 {
458  struct dir_private_info *info = filp->private_data;
459  loff_t curr_pos;
460  struct inode *inode = filp->f_path.dentry->d_inode;
461  struct super_block * sb;
462  int error;
463 
464  sb = inode->i_sb;
465 
466  if (!fname) {
467  printk("call_filldir: called with null fname?!?\n");
468  return 0;
469  }
470  curr_pos = hash2pos(filp, fname->hash, fname->minor_hash);
471  while (fname) {
472  error = filldir(dirent, fname->name,
473  fname->name_len, curr_pos,
474  fname->inode,
475  get_dtype(sb, fname->file_type));
476  if (error) {
477  filp->f_pos = curr_pos;
478  info->extra_fname = fname;
479  return error;
480  }
481  fname = fname->next;
482  }
483  return 0;
484 }
485 
486 static int ext3_dx_readdir(struct file * filp,
487  void * dirent, filldir_t filldir)
488 {
489  struct dir_private_info *info = filp->private_data;
490  struct inode *inode = filp->f_path.dentry->d_inode;
491  struct fname *fname;
492  int ret;
493 
494  if (!info) {
495  info = ext3_htree_create_dir_info(filp, filp->f_pos);
496  if (!info)
497  return -ENOMEM;
498  filp->private_data = info;
499  }
500 
501  if (filp->f_pos == ext3_get_htree_eof(filp))
502  return 0; /* EOF */
503 
504  /* Some one has messed with f_pos; reset the world */
505  if (info->last_pos != filp->f_pos) {
506  free_rb_tree_fname(&info->root);
507  info->curr_node = NULL;
508  info->extra_fname = NULL;
509  info->curr_hash = pos2maj_hash(filp, filp->f_pos);
510  info->curr_minor_hash = pos2min_hash(filp, filp->f_pos);
511  }
512 
513  /*
514  * If there are any leftover names on the hash collision
515  * chain, return them first.
516  */
517  if (info->extra_fname) {
518  if (call_filldir(filp, dirent, filldir, info->extra_fname))
519  goto finished;
520  info->extra_fname = NULL;
521  goto next_node;
522  } else if (!info->curr_node)
523  info->curr_node = rb_first(&info->root);
524 
525  while (1) {
526  /*
527  * Fill the rbtree if we have no more entries,
528  * or the inode has changed since we last read in the
529  * cached entries.
530  */
531  if ((!info->curr_node) ||
532  (filp->f_version != inode->i_version)) {
533  info->curr_node = NULL;
534  free_rb_tree_fname(&info->root);
535  filp->f_version = inode->i_version;
536  ret = ext3_htree_fill_tree(filp, info->curr_hash,
537  info->curr_minor_hash,
538  &info->next_hash);
539  if (ret < 0)
540  return ret;
541  if (ret == 0) {
542  filp->f_pos = ext3_get_htree_eof(filp);
543  break;
544  }
545  info->curr_node = rb_first(&info->root);
546  }
547 
548  fname = rb_entry(info->curr_node, struct fname, rb_hash);
549  info->curr_hash = fname->hash;
550  info->curr_minor_hash = fname->minor_hash;
551  if (call_filldir(filp, dirent, filldir, fname))
552  break;
553  next_node:
554  info->curr_node = rb_next(info->curr_node);
555  if (info->curr_node) {
556  fname = rb_entry(info->curr_node, struct fname,
557  rb_hash);
558  info->curr_hash = fname->hash;
559  info->curr_minor_hash = fname->minor_hash;
560  } else {
561  if (info->next_hash == ~0) {
562  filp->f_pos = ext3_get_htree_eof(filp);
563  break;
564  }
565  info->curr_hash = info->next_hash;
566  info->curr_minor_hash = 0;
567  }
568  }
569 finished:
570  info->last_pos = filp->f_pos;
571  return 0;
572 }
573 
574 static int ext3_release_dir (struct inode * inode, struct file * filp)
575 {
576  if (filp->private_data)
578 
579  return 0;
580 }
581 
583  .llseek = ext3_dir_llseek,
584  .read = generic_read_dir,
585  .readdir = ext3_readdir,
586  .unlocked_ioctl = ext3_ioctl,
587 #ifdef CONFIG_COMPAT
588  .compat_ioctl = ext3_compat_ioctl,
589 #endif
590  .fsync = ext3_sync_file,
591  .release = ext3_release_dir,
592 };