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TOMOYO Linux Cross Reference
Linux/fs/ext3/dir.c

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  1 /*
  2  *  linux/fs/ext3/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  *  ext3 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/compat.h>
 25 #include "ext3.h"
 26 
 27 static unsigned char ext3_filetype_table[] = {
 28         DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK, DT_FIFO, DT_SOCK, DT_LNK
 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 {
 36         if (!EXT3_HAS_INCOMPAT_FEATURE(sb, EXT3_FEATURE_INCOMPAT_FILETYPE) ||
 37             (filetype >= EXT3_FT_MAX))
 38                 return DT_UNKNOWN;
 39 
 40         return (ext3_filetype_table[filetype]);
 41 }
 42 
 43 /**
 44  * Check if the given dir-inode refers to an htree-indexed directory
 45  * (or a directory which chould potentially get coverted to use htree
 46  * indexing).
 47  *
 48  * Return 1 if it is a dx dir, 0 if not
 49  */
 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,
 55                      EXT3_FEATURE_COMPAT_DIR_INDEX) &&
 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))
133                                 page_cache_sync_readahead(
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
186                        && offset < sb->s_blocksize) {
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 
304         if (likely(dx_dir))
305                 return generic_file_llseek_size(file, offset, origin,
306                                                 ext3_get_htree_eof(file));
307         else
308                 return generic_file_llseek(file, offset, origin);
309 }
310 
311 /*
312  * This structure holds the nodes of the red-black tree used to store
313  * the directory entry in hash order.
314  */
315 struct fname {
316         __u32           hash;
317         __u32           minor_hash;
318         struct rb_node  rb_hash;
319         struct fname    *next;
320         __u32           inode;
321         __u8            name_len;
322         __u8            file_type;
323         char            name[0];
324 };
325 
326 /*
327  * This functoin implements a non-recursive way of freeing all of the
328  * nodes in the red-black tree.
329  */
330 static void free_rb_tree_fname(struct rb_root *root)
331 {
332         struct rb_node  *n = root->rb_node;
333         struct rb_node  *parent;
334         struct fname    *fname;
335 
336         while (n) {
337                 /* Do the node's children first */
338                 if (n->rb_left) {
339                         n = n->rb_left;
340                         continue;
341                 }
342                 if (n->rb_right) {
343                         n = n->rb_right;
344                         continue;
345                 }
346                 /*
347                  * The node has no children; free it, and then zero
348                  * out parent's link to it.  Finally go to the
349                  * beginning of the loop and try to free the parent
350                  * node.
351                  */
352                 parent = rb_parent(n);
353                 fname = rb_entry(n, struct fname, rb_hash);
354                 while (fname) {
355                         struct fname * old = fname;
356                         fname = fname->next;
357                         kfree (old);
358                 }
359                 if (!parent)
360                         *root = RB_ROOT;
361                 else if (parent->rb_left == n)
362                         parent->rb_left = NULL;
363                 else if (parent->rb_right == n)
364                         parent->rb_right = NULL;
365                 n = parent;
366         }
367 }
368 
369 
370 static struct dir_private_info *ext3_htree_create_dir_info(struct file *filp,
371                                                            loff_t pos)
372 {
373         struct dir_private_info *p;
374 
375         p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL);
376         if (!p)
377                 return NULL;
378         p->curr_hash = pos2maj_hash(filp, pos);
379         p->curr_minor_hash = pos2min_hash(filp, pos);
380         return p;
381 }
382 
383 void ext3_htree_free_dir_info(struct dir_private_info *p)
384 {
385         free_rb_tree_fname(&p->root);
386         kfree(p);
387 }
388 
389 /*
390  * Given a directory entry, enter it into the fname rb tree.
391  */
392 int ext3_htree_store_dirent(struct file *dir_file, __u32 hash,
393                              __u32 minor_hash,
394                              struct ext3_dir_entry_2 *dirent)
395 {
396         struct rb_node **p, *parent = NULL;
397         struct fname * fname, *new_fn;
398         struct dir_private_info *info;
399         int len;
400 
401         info = (struct dir_private_info *) dir_file->private_data;
402         p = &info->root.rb_node;
403 
404         /* Create and allocate the fname structure */
405         len = sizeof(struct fname) + dirent->name_len + 1;
406         new_fn = kzalloc(len, GFP_KERNEL);
407         if (!new_fn)
408                 return -ENOMEM;
409         new_fn->hash = hash;
410         new_fn->minor_hash = minor_hash;
411         new_fn->inode = le32_to_cpu(dirent->inode);
412         new_fn->name_len = dirent->name_len;
413         new_fn->file_type = dirent->file_type;
414         memcpy(new_fn->name, dirent->name, dirent->name_len);
415         new_fn->name[dirent->name_len] = 0;
416 
417         while (*p) {
418                 parent = *p;
419                 fname = rb_entry(parent, struct fname, rb_hash);
420 
421                 /*
422                  * If the hash and minor hash match up, then we put
423                  * them on a linked list.  This rarely happens...
424                  */
425                 if ((new_fn->hash == fname->hash) &&
426                     (new_fn->minor_hash == fname->minor_hash)) {
427                         new_fn->next = fname->next;
428                         fname->next = new_fn;
429                         return 0;
430                 }
431 
432                 if (new_fn->hash < fname->hash)
433                         p = &(*p)->rb_left;
434                 else if (new_fn->hash > fname->hash)
435                         p = &(*p)->rb_right;
436                 else if (new_fn->minor_hash < fname->minor_hash)
437                         p = &(*p)->rb_left;
438                 else /* if (new_fn->minor_hash > fname->minor_hash) */
439                         p = &(*p)->rb_right;
440         }
441 
442         rb_link_node(&new_fn->rb_hash, parent, p);
443         rb_insert_color(&new_fn->rb_hash, &info->root);
444         return 0;
445 }
446 
447 
448 
449 /*
450  * This is a helper function for ext3_dx_readdir.  It calls filldir
451  * for all entres on the fname linked list.  (Normally there is only
452  * one entry on the linked list, unless there are 62 bit hash collisions.)
453  */
454 static int call_filldir(struct file * filp, void * dirent,
455                         filldir_t filldir, struct fname *fname)
456 {
457         struct dir_private_info *info = filp->private_data;
458         loff_t  curr_pos;
459         struct inode *inode = filp->f_path.dentry->d_inode;
460         struct super_block * sb;
461         int error;
462 
463         sb = inode->i_sb;
464 
465         if (!fname) {
466                 printk("call_filldir: called with null fname?!?\n");
467                 return 0;
468         }
469         curr_pos = hash2pos(filp, fname->hash, fname->minor_hash);
470         while (fname) {
471                 error = filldir(dirent, fname->name,
472                                 fname->name_len, curr_pos,
473                                 fname->inode,
474                                 get_dtype(sb, fname->file_type));
475                 if (error) {
476                         filp->f_pos = curr_pos;
477                         info->extra_fname = fname;
478                         return error;
479                 }
480                 fname = fname->next;
481         }
482         return 0;
483 }
484 
485 static int ext3_dx_readdir(struct file * filp,
486                          void * dirent, filldir_t filldir)
487 {
488         struct dir_private_info *info = filp->private_data;
489         struct inode *inode = filp->f_path.dentry->d_inode;
490         struct fname *fname;
491         int     ret;
492 
493         if (!info) {
494                 info = ext3_htree_create_dir_info(filp, filp->f_pos);
495                 if (!info)
496                         return -ENOMEM;
497                 filp->private_data = info;
498         }
499 
500         if (filp->f_pos == ext3_get_htree_eof(filp))
501                 return 0;       /* EOF */
502 
503         /* Some one has messed with f_pos; reset the world */
504         if (info->last_pos != filp->f_pos) {
505                 free_rb_tree_fname(&info->root);
506                 info->curr_node = NULL;
507                 info->extra_fname = NULL;
508                 info->curr_hash = pos2maj_hash(filp, filp->f_pos);
509                 info->curr_minor_hash = pos2min_hash(filp, filp->f_pos);
510         }
511 
512         /*
513          * If there are any leftover names on the hash collision
514          * chain, return them first.
515          */
516         if (info->extra_fname) {
517                 if (call_filldir(filp, dirent, filldir, info->extra_fname))
518                         goto finished;
519                 info->extra_fname = NULL;
520                 goto next_node;
521         } else if (!info->curr_node)
522                 info->curr_node = rb_first(&info->root);
523 
524         while (1) {
525                 /*
526                  * Fill the rbtree if we have no more entries,
527                  * or the inode has changed since we last read in the
528                  * cached entries.
529                  */
530                 if ((!info->curr_node) ||
531                     (filp->f_version != inode->i_version)) {
532                         info->curr_node = NULL;
533                         free_rb_tree_fname(&info->root);
534                         filp->f_version = inode->i_version;
535                         ret = ext3_htree_fill_tree(filp, info->curr_hash,
536                                                    info->curr_minor_hash,
537                                                    &info->next_hash);
538                         if (ret < 0)
539                                 return ret;
540                         if (ret == 0) {
541                                 filp->f_pos = ext3_get_htree_eof(filp);
542                                 break;
543                         }
544                         info->curr_node = rb_first(&info->root);
545                 }
546 
547                 fname = rb_entry(info->curr_node, struct fname, rb_hash);
548                 info->curr_hash = fname->hash;
549                 info->curr_minor_hash = fname->minor_hash;
550                 if (call_filldir(filp, dirent, filldir, fname))
551                         break;
552         next_node:
553                 info->curr_node = rb_next(info->curr_node);
554                 if (info->curr_node) {
555                         fname = rb_entry(info->curr_node, struct fname,
556                                          rb_hash);
557                         info->curr_hash = fname->hash;
558                         info->curr_minor_hash = fname->minor_hash;
559                 } else {
560                         if (info->next_hash == ~0) {
561                                 filp->f_pos = ext3_get_htree_eof(filp);
562                                 break;
563                         }
564                         info->curr_hash = info->next_hash;
565                         info->curr_minor_hash = 0;
566                 }
567         }
568 finished:
569         info->last_pos = filp->f_pos;
570         return 0;
571 }
572 
573 static int ext3_release_dir (struct inode * inode, struct file * filp)
574 {
575        if (filp->private_data)
576                 ext3_htree_free_dir_info(filp->private_data);
577 
578         return 0;
579 }
580 
581 const struct file_operations ext3_dir_operations = {
582         .llseek         = ext3_dir_llseek,
583         .read           = generic_read_dir,
584         .readdir        = ext3_readdir,
585         .unlocked_ioctl = ext3_ioctl,
586 #ifdef CONFIG_COMPAT
587         .compat_ioctl   = ext3_compat_ioctl,
588 #endif
589         .fsync          = ext3_sync_file,
590         .release        = ext3_release_dir,
591 };
592 

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