Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...
[linux-2.6] / 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 long offset)
68 {
69         const char *error_msg = NULL;
70         const int rlen = ext4_rec_len_from_disk(de->rec_len);
71
72         if (rlen < EXT4_DIR_REC_LEN(1))
73                 error_msg = "rec_len is smaller than minimal";
74         else if (rlen % 4 != 0)
75                 error_msg = "rec_len % 4 != 0";
76         else if (rlen < EXT4_DIR_REC_LEN(de->name_len))
77                 error_msg = "rec_len is too small for name_len";
78         else if (((char *) de - bh->b_data) + rlen > dir->i_sb->s_blocksize)
79                 error_msg = "directory entry across blocks";
80         else if (le32_to_cpu(de->inode) >
81                         le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count))
82                 error_msg = "inode out of bounds";
83
84         if (error_msg != NULL)
85                 ext4_error(dir->i_sb, function,
86                         "bad entry in directory #%lu: %s - "
87                         "offset=%lu, inode=%lu, rec_len=%d, name_len=%d",
88                         dir->i_ino, error_msg, offset,
89                         (unsigned long) le32_to_cpu(de->inode),
90                         rlen, de->name_len);
91         return error_msg == NULL ? 1 : 0;
92 }
93
94 static int ext4_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 ext4_dir_entry_2 *de;
101         struct super_block *sb;
102         int err;
103         struct inode *inode = filp->f_path.dentry->d_inode;
104         int ret = 0;
105         int dir_has_error = 0;
106
107         sb = inode->i_sb;
108
109         if (EXT4_HAS_COMPAT_FEATURE(inode->i_sb,
110                                     EXT4_FEATURE_COMPAT_DIR_INDEX) &&
111             ((EXT4_I(inode)->i_flags & EXT4_INDEX_FL) ||
112              ((inode->i_size >> sb->s_blocksize_bits) == 1))) {
113                 err = ext4_dx_readdir(filp, dirent, filldir);
114                 if (err != ERR_BAD_DX_DIR) {
115                         ret = err;
116                         goto out;
117                 }
118                 /*
119                  * We don't set the inode dirty flag since it's not
120                  * critical that it get flushed back to the disk.
121                  */
122                 EXT4_I(filp->f_path.dentry->d_inode)->i_flags &= ~EXT4_INDEX_FL;
123         }
124         stored = 0;
125         offset = filp->f_pos & (sb->s_blocksize - 1);
126
127         while (!error && !stored && filp->f_pos < inode->i_size) {
128                 ext4_lblk_t blk = filp->f_pos >> EXT4_BLOCK_SIZE_BITS(sb);
129                 struct buffer_head map_bh;
130                 struct buffer_head *bh = NULL;
131
132                 map_bh.b_state = 0;
133                 err = ext4_get_blocks_wrap(NULL, inode, blk, 1, &map_bh,
134                                                 0, 0, 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                                                 < EXT4_DIR_REC_LEN(1))
183                                         break;
184                                 i += ext4_rec_len_from_disk(de->rec_len);
185                         }
186                         offset = i;
187                         filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1))
188                                 | offset;
189                         filp->f_version = inode->i_version;
190                 }
191
192                 while (!error && filp->f_pos < inode->i_size
193                        && offset < sb->s_blocksize) {
194                         de = (struct ext4_dir_entry_2 *) (bh->b_data + offset);
195                         if (!ext4_check_dir_entry("ext4_readdir", inode, de,
196                                                   bh, offset)) {
197                                 /*
198                                  * On error, skip the f_pos to the next block
199                                  */
200                                 filp->f_pos = (filp->f_pos |
201                                                 (sb->s_blocksize - 1)) + 1;
202                                 brelse(bh);
203                                 ret = stored;
204                                 goto out;
205                         }
206                         offset += ext4_rec_len_from_disk(de->rec_len);
207                         if (le32_to_cpu(de->inode)) {
208                                 /* We might block in the next section
209                                  * if the data destination is
210                                  * currently swapped out.  So, use a
211                                  * version stamp to detect whether or
212                                  * not the directory has been modified
213                                  * during the copy operation.
214                                  */
215                                 u64 version = filp->f_version;
216
217                                 error = filldir(dirent, de->name,
218                                                 de->name_len,
219                                                 filp->f_pos,
220                                                 le32_to_cpu(de->inode),
221                                                 get_dtype(sb, de->file_type));
222                                 if (error)
223                                         break;
224                                 if (version != filp->f_version)
225                                         goto revalidate;
226                                 stored++;
227                         }
228                         filp->f_pos += ext4_rec_len_from_disk(de->rec_len);
229                 }
230                 offset = 0;
231                 brelse(bh);
232         }
233 out:
234         return ret;
235 }
236
237 /*
238  * These functions convert from the major/minor hash to an f_pos
239  * value.
240  *
241  * Currently we only use major hash numer.  This is unfortunate, but
242  * on 32-bit machines, the same VFS interface is used for lseek and
243  * llseek, so if we use the 64 bit offset, then the 32-bit versions of
244  * lseek/telldir/seekdir will blow out spectacularly, and from within
245  * the ext2 low-level routine, we don't know if we're being called by
246  * a 64-bit version of the system call or the 32-bit version of the
247  * system call.  Worse yet, NFSv2 only allows for a 32-bit readdir
248  * cookie.  Sigh.
249  */
250 #define hash2pos(major, minor)  (major >> 1)
251 #define pos2maj_hash(pos)       ((pos << 1) & 0xffffffff)
252 #define pos2min_hash(pos)       (0)
253
254 /*
255  * This structure holds the nodes of the red-black tree used to store
256  * the directory entry in hash order.
257  */
258 struct fname {
259         __u32           hash;
260         __u32           minor_hash;
261         struct rb_node  rb_hash;
262         struct fname    *next;
263         __u32           inode;
264         __u8            name_len;
265         __u8            file_type;
266         char            name[0];
267 };
268
269 /*
270  * This functoin implements a non-recursive way of freeing all of the
271  * nodes in the red-black tree.
272  */
273 static void free_rb_tree_fname(struct rb_root *root)
274 {
275         struct rb_node  *n = root->rb_node;
276         struct rb_node  *parent;
277         struct fname    *fname;
278
279         while (n) {
280                 /* Do the node's children first */
281                 if (n->rb_left) {
282                         n = n->rb_left;
283                         continue;
284                 }
285                 if (n->rb_right) {
286                         n = n->rb_right;
287                         continue;
288                 }
289                 /*
290                  * The node has no children; free it, and then zero
291                  * out parent's link to it.  Finally go to the
292                  * beginning of the loop and try to free the parent
293                  * node.
294                  */
295                 parent = rb_parent(n);
296                 fname = rb_entry(n, struct fname, rb_hash);
297                 while (fname) {
298                         struct fname *old = fname;
299                         fname = fname->next;
300                         kfree(old);
301                 }
302                 if (!parent)
303                         root->rb_node = NULL;
304                 else if (parent->rb_left == n)
305                         parent->rb_left = NULL;
306                 else if (parent->rb_right == n)
307                         parent->rb_right = NULL;
308                 n = parent;
309         }
310 }
311
312
313 static struct dir_private_info *ext4_htree_create_dir_info(loff_t pos)
314 {
315         struct dir_private_info *p;
316
317         p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL);
318         if (!p)
319                 return NULL;
320         p->curr_hash = pos2maj_hash(pos);
321         p->curr_minor_hash = pos2min_hash(pos);
322         return p;
323 }
324
325 void ext4_htree_free_dir_info(struct dir_private_info *p)
326 {
327         free_rb_tree_fname(&p->root);
328         kfree(p);
329 }
330
331 /*
332  * Given a directory entry, enter it into the fname rb tree.
333  */
334 int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,
335                              __u32 minor_hash,
336                              struct ext4_dir_entry_2 *dirent)
337 {
338         struct rb_node **p, *parent = NULL;
339         struct fname *fname, *new_fn;
340         struct dir_private_info *info;
341         int len;
342
343         info = (struct dir_private_info *) dir_file->private_data;
344         p = &info->root.rb_node;
345
346         /* Create and allocate the fname structure */
347         len = sizeof(struct fname) + dirent->name_len + 1;
348         new_fn = kzalloc(len, GFP_KERNEL);
349         if (!new_fn)
350                 return -ENOMEM;
351         new_fn->hash = hash;
352         new_fn->minor_hash = minor_hash;
353         new_fn->inode = le32_to_cpu(dirent->inode);
354         new_fn->name_len = dirent->name_len;
355         new_fn->file_type = dirent->file_type;
356         memcpy(new_fn->name, dirent->name, dirent->name_len);
357         new_fn->name[dirent->name_len] = 0;
358
359         while (*p) {
360                 parent = *p;
361                 fname = rb_entry(parent, struct fname, rb_hash);
362
363                 /*
364                  * If the hash and minor hash match up, then we put
365                  * them on a linked list.  This rarely happens...
366                  */
367                 if ((new_fn->hash == fname->hash) &&
368                     (new_fn->minor_hash == fname->minor_hash)) {
369                         new_fn->next = fname->next;
370                         fname->next = new_fn;
371                         return 0;
372                 }
373
374                 if (new_fn->hash < fname->hash)
375                         p = &(*p)->rb_left;
376                 else if (new_fn->hash > fname->hash)
377                         p = &(*p)->rb_right;
378                 else if (new_fn->minor_hash < fname->minor_hash)
379                         p = &(*p)->rb_left;
380                 else /* if (new_fn->minor_hash > fname->minor_hash) */
381                         p = &(*p)->rb_right;
382         }
383
384         rb_link_node(&new_fn->rb_hash, parent, p);
385         rb_insert_color(&new_fn->rb_hash, &info->root);
386         return 0;
387 }
388
389
390
391 /*
392  * This is a helper function for ext4_dx_readdir.  It calls filldir
393  * for all entres on the fname linked list.  (Normally there is only
394  * one entry on the linked list, unless there are 62 bit hash collisions.)
395  */
396 static int call_filldir(struct file *filp, void *dirent,
397                         filldir_t filldir, struct fname *fname)
398 {
399         struct dir_private_info *info = filp->private_data;
400         loff_t  curr_pos;
401         struct inode *inode = filp->f_path.dentry->d_inode;
402         struct super_block *sb;
403         int error;
404
405         sb = inode->i_sb;
406
407         if (!fname) {
408                 printk(KERN_ERR "ext4: call_filldir: called with "
409                        "null fname?!?\n");
410                 return 0;
411         }
412         curr_pos = hash2pos(fname->hash, fname->minor_hash);
413         while (fname) {
414                 error = filldir(dirent, fname->name,
415                                 fname->name_len, curr_pos,
416                                 fname->inode,
417                                 get_dtype(sb, fname->file_type));
418                 if (error) {
419                         filp->f_pos = curr_pos;
420                         info->extra_fname = fname;
421                         return error;
422                 }
423                 fname = fname->next;
424         }
425         return 0;
426 }
427
428 static int ext4_dx_readdir(struct file *filp,
429                          void *dirent, filldir_t filldir)
430 {
431         struct dir_private_info *info = filp->private_data;
432         struct inode *inode = filp->f_path.dentry->d_inode;
433         struct fname *fname;
434         int     ret;
435
436         if (!info) {
437                 info = ext4_htree_create_dir_info(filp->f_pos);
438                 if (!info)
439                         return -ENOMEM;
440                 filp->private_data = info;
441         }
442
443         if (filp->f_pos == EXT4_HTREE_EOF)
444                 return 0;       /* EOF */
445
446         /* Some one has messed with f_pos; reset the world */
447         if (info->last_pos != filp->f_pos) {
448                 free_rb_tree_fname(&info->root);
449                 info->curr_node = NULL;
450                 info->extra_fname = NULL;
451                 info->curr_hash = pos2maj_hash(filp->f_pos);
452                 info->curr_minor_hash = pos2min_hash(filp->f_pos);
453         }
454
455         /*
456          * If there are any leftover names on the hash collision
457          * chain, return them first.
458          */
459         if (info->extra_fname) {
460                 if (call_filldir(filp, dirent, filldir, info->extra_fname))
461                         goto finished;
462                 info->extra_fname = NULL;
463                 goto next_node;
464         } else if (!info->curr_node)
465                 info->curr_node = rb_first(&info->root);
466
467         while (1) {
468                 /*
469                  * Fill the rbtree if we have no more entries,
470                  * or the inode has changed since we last read in the
471                  * cached entries.
472                  */
473                 if ((!info->curr_node) ||
474                     (filp->f_version != inode->i_version)) {
475                         info->curr_node = NULL;
476                         free_rb_tree_fname(&info->root);
477                         filp->f_version = inode->i_version;
478                         ret = ext4_htree_fill_tree(filp, info->curr_hash,
479                                                    info->curr_minor_hash,
480                                                    &info->next_hash);
481                         if (ret < 0)
482                                 return ret;
483                         if (ret == 0) {
484                                 filp->f_pos = EXT4_HTREE_EOF;
485                                 break;
486                         }
487                         info->curr_node = rb_first(&info->root);
488                 }
489
490                 fname = rb_entry(info->curr_node, struct fname, rb_hash);
491                 info->curr_hash = fname->hash;
492                 info->curr_minor_hash = fname->minor_hash;
493                 if (call_filldir(filp, dirent, filldir, fname))
494                         break;
495         next_node:
496                 info->curr_node = rb_next(info->curr_node);
497                 if (info->curr_node) {
498                         fname = rb_entry(info->curr_node, struct fname,
499                                          rb_hash);
500                         info->curr_hash = fname->hash;
501                         info->curr_minor_hash = fname->minor_hash;
502                 } else {
503                         if (info->next_hash == ~0) {
504                                 filp->f_pos = EXT4_HTREE_EOF;
505                                 break;
506                         }
507                         info->curr_hash = info->next_hash;
508                         info->curr_minor_hash = 0;
509                 }
510         }
511 finished:
512         info->last_pos = filp->f_pos;
513         return 0;
514 }
515
516 static int ext4_release_dir(struct inode *inode, struct file *filp)
517 {
518         if (filp->private_data)
519                 ext4_htree_free_dir_info(filp->private_data);
520
521         return 0;
522 }