ext4: simple cleanups to write_cache_pages_da()
[linux-2.6.git] / 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  * Return 0 if the directory entry is OK, and 1 if there is a problem
65  *
66  * Note: this is the opposite of what ext2 and ext3 historically returned...
67  */
68 int __ext4_check_dir_entry(const char *function, unsigned int line,
69                            struct inode *dir, struct file *filp,
70                            struct ext4_dir_entry_2 *de,
71                            struct buffer_head *bh,
72                            unsigned int offset)
73 {
74         const char *error_msg = NULL;
75         const int rlen = ext4_rec_len_from_disk(de->rec_len,
76                                                 dir->i_sb->s_blocksize);
77
78         if (unlikely(rlen < EXT4_DIR_REC_LEN(1)))
79                 error_msg = "rec_len is smaller than minimal";
80         else if (unlikely(rlen % 4 != 0))
81                 error_msg = "rec_len % 4 != 0";
82         else if (unlikely(rlen < EXT4_DIR_REC_LEN(de->name_len)))
83                 error_msg = "rec_len is too small for name_len";
84         else if (unlikely(((char *) de - bh->b_data) + rlen >
85                           dir->i_sb->s_blocksize))
86                 error_msg = "directory entry across blocks";
87         else if (unlikely(le32_to_cpu(de->inode) >
88                         le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count)))
89                 error_msg = "inode out of bounds";
90         else
91                 return 0;
92
93         if (filp)
94                 ext4_error_file(filp, function, line, bh ? bh->b_blocknr : 0,
95                                 "bad entry in directory: %s - offset=%u(%u), "
96                                 "inode=%u, rec_len=%d, name_len=%d",
97                                 error_msg, (unsigned) (offset%bh->b_size),
98                                 offset, le32_to_cpu(de->inode),
99                                 rlen, de->name_len);
100         else
101                 ext4_error_inode(dir, function, line, bh ? bh->b_blocknr : 0,
102                                 "bad entry in directory: %s - offset=%u(%u), "
103                                 "inode=%u, rec_len=%d, name_len=%d",
104                                 error_msg, (unsigned) (offset%bh->b_size),
105                                 offset, le32_to_cpu(de->inode),
106                                 rlen, de->name_len);
107
108         return 1;
109 }
110
111 static int ext4_readdir(struct file *filp,
112                          void *dirent, filldir_t filldir)
113 {
114         int error = 0;
115         unsigned int offset;
116         int i, stored;
117         struct ext4_dir_entry_2 *de;
118         struct super_block *sb;
119         int err;
120         struct inode *inode = filp->f_path.dentry->d_inode;
121         int ret = 0;
122         int dir_has_error = 0;
123
124         sb = inode->i_sb;
125
126         if (EXT4_HAS_COMPAT_FEATURE(inode->i_sb,
127                                     EXT4_FEATURE_COMPAT_DIR_INDEX) &&
128             ((ext4_test_inode_flag(inode, EXT4_INODE_INDEX)) ||
129              ((inode->i_size >> sb->s_blocksize_bits) == 1))) {
130                 err = ext4_dx_readdir(filp, dirent, filldir);
131                 if (err != ERR_BAD_DX_DIR) {
132                         ret = err;
133                         goto out;
134                 }
135                 /*
136                  * We don't set the inode dirty flag since it's not
137                  * critical that it get flushed back to the disk.
138                  */
139                 ext4_clear_inode_flag(filp->f_path.dentry->d_inode,
140                                       EXT4_INODE_INDEX);
141         }
142         stored = 0;
143         offset = filp->f_pos & (sb->s_blocksize - 1);
144
145         while (!error && !stored && filp->f_pos < inode->i_size) {
146                 struct ext4_map_blocks map;
147                 struct buffer_head *bh = NULL;
148
149                 map.m_lblk = filp->f_pos >> EXT4_BLOCK_SIZE_BITS(sb);
150                 map.m_len = 1;
151                 err = ext4_map_blocks(NULL, inode, &map, 0);
152                 if (err > 0) {
153                         pgoff_t index = map.m_pblk >>
154                                         (PAGE_CACHE_SHIFT - inode->i_blkbits);
155                         if (!ra_has_index(&filp->f_ra, index))
156                                 page_cache_sync_readahead(
157                                         sb->s_bdev->bd_inode->i_mapping,
158                                         &filp->f_ra, filp,
159                                         index, 1);
160                         filp->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT;
161                         bh = ext4_bread(NULL, inode, map.m_lblk, 0, &err);
162                 }
163
164                 /*
165                  * We ignore I/O errors on directories so users have a chance
166                  * of recovering data when there's a bad sector
167                  */
168                 if (!bh) {
169                         if (!dir_has_error) {
170                                 EXT4_ERROR_FILE(filp, 0,
171                                                 "directory contains a "
172                                                 "hole at offset %llu",
173                                            (unsigned long long) filp->f_pos);
174                                 dir_has_error = 1;
175                         }
176                         /* corrupt size?  Maybe no more blocks to read */
177                         if (filp->f_pos > inode->i_blocks << 9)
178                                 break;
179                         filp->f_pos += sb->s_blocksize - offset;
180                         continue;
181                 }
182
183 revalidate:
184                 /* If the dir block has changed since the last call to
185                  * readdir(2), then we might be pointing to an invalid
186                  * dirent right now.  Scan from the start of the block
187                  * to make sure. */
188                 if (filp->f_version != inode->i_version) {
189                         for (i = 0; i < sb->s_blocksize && i < offset; ) {
190                                 de = (struct ext4_dir_entry_2 *)
191                                         (bh->b_data + i);
192                                 /* It's too expensive to do a full
193                                  * dirent test each time round this
194                                  * loop, but we do have to test at
195                                  * least that it is non-zero.  A
196                                  * failure will be detected in the
197                                  * dirent test below. */
198                                 if (ext4_rec_len_from_disk(de->rec_len,
199                                         sb->s_blocksize) < EXT4_DIR_REC_LEN(1))
200                                         break;
201                                 i += ext4_rec_len_from_disk(de->rec_len,
202                                                             sb->s_blocksize);
203                         }
204                         offset = i;
205                         filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1))
206                                 | offset;
207                         filp->f_version = inode->i_version;
208                 }
209
210                 while (!error && filp->f_pos < inode->i_size
211                        && offset < sb->s_blocksize) {
212                         de = (struct ext4_dir_entry_2 *) (bh->b_data + offset);
213                         if (ext4_check_dir_entry(inode, filp, de,
214                                                  bh, offset)) {
215                                 /*
216                                  * On error, skip the f_pos to the next block
217                                  */
218                                 filp->f_pos = (filp->f_pos |
219                                                 (sb->s_blocksize - 1)) + 1;
220                                 brelse(bh);
221                                 ret = stored;
222                                 goto out;
223                         }
224                         offset += ext4_rec_len_from_disk(de->rec_len,
225                                         sb->s_blocksize);
226                         if (le32_to_cpu(de->inode)) {
227                                 /* We might block in the next section
228                                  * if the data destination is
229                                  * currently swapped out.  So, use a
230                                  * version stamp to detect whether or
231                                  * not the directory has been modified
232                                  * during the copy operation.
233                                  */
234                                 u64 version = filp->f_version;
235
236                                 error = filldir(dirent, de->name,
237                                                 de->name_len,
238                                                 filp->f_pos,
239                                                 le32_to_cpu(de->inode),
240                                                 get_dtype(sb, de->file_type));
241                                 if (error)
242                                         break;
243                                 if (version != filp->f_version)
244                                         goto revalidate;
245                                 stored++;
246                         }
247                         filp->f_pos += ext4_rec_len_from_disk(de->rec_len,
248                                                 sb->s_blocksize);
249                 }
250                 offset = 0;
251                 brelse(bh);
252         }
253 out:
254         return ret;
255 }
256
257 /*
258  * These functions convert from the major/minor hash to an f_pos
259  * value.
260  *
261  * Currently we only use major hash numer.  This is unfortunate, but
262  * on 32-bit machines, the same VFS interface is used for lseek and
263  * llseek, so if we use the 64 bit offset, then the 32-bit versions of
264  * lseek/telldir/seekdir will blow out spectacularly, and from within
265  * the ext2 low-level routine, we don't know if we're being called by
266  * a 64-bit version of the system call or the 32-bit version of the
267  * system call.  Worse yet, NFSv2 only allows for a 32-bit readdir
268  * cookie.  Sigh.
269  */
270 #define hash2pos(major, minor)  (major >> 1)
271 #define pos2maj_hash(pos)       ((pos << 1) & 0xffffffff)
272 #define pos2min_hash(pos)       (0)
273
274 /*
275  * This structure holds the nodes of the red-black tree used to store
276  * the directory entry in hash order.
277  */
278 struct fname {
279         __u32           hash;
280         __u32           minor_hash;
281         struct rb_node  rb_hash;
282         struct fname    *next;
283         __u32           inode;
284         __u8            name_len;
285         __u8            file_type;
286         char            name[0];
287 };
288
289 /*
290  * This functoin implements a non-recursive way of freeing all of the
291  * nodes in the red-black tree.
292  */
293 static void free_rb_tree_fname(struct rb_root *root)
294 {
295         struct rb_node  *n = root->rb_node;
296         struct rb_node  *parent;
297         struct fname    *fname;
298
299         while (n) {
300                 /* Do the node's children first */
301                 if (n->rb_left) {
302                         n = n->rb_left;
303                         continue;
304                 }
305                 if (n->rb_right) {
306                         n = n->rb_right;
307                         continue;
308                 }
309                 /*
310                  * The node has no children; free it, and then zero
311                  * out parent's link to it.  Finally go to the
312                  * beginning of the loop and try to free the parent
313                  * node.
314                  */
315                 parent = rb_parent(n);
316                 fname = rb_entry(n, struct fname, rb_hash);
317                 while (fname) {
318                         struct fname *old = fname;
319                         fname = fname->next;
320                         kfree(old);
321                 }
322                 if (!parent)
323                         *root = RB_ROOT;
324                 else if (parent->rb_left == n)
325                         parent->rb_left = NULL;
326                 else if (parent->rb_right == n)
327                         parent->rb_right = NULL;
328                 n = parent;
329         }
330 }
331
332
333 static struct dir_private_info *ext4_htree_create_dir_info(loff_t pos)
334 {
335         struct dir_private_info *p;
336
337         p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL);
338         if (!p)
339                 return NULL;
340         p->curr_hash = pos2maj_hash(pos);
341         p->curr_minor_hash = pos2min_hash(pos);
342         return p;
343 }
344
345 void ext4_htree_free_dir_info(struct dir_private_info *p)
346 {
347         free_rb_tree_fname(&p->root);
348         kfree(p);
349 }
350
351 /*
352  * Given a directory entry, enter it into the fname rb tree.
353  */
354 int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,
355                              __u32 minor_hash,
356                              struct ext4_dir_entry_2 *dirent)
357 {
358         struct rb_node **p, *parent = NULL;
359         struct fname *fname, *new_fn;
360         struct dir_private_info *info;
361         int len;
362
363         info = dir_file->private_data;
364         p = &info->root.rb_node;
365
366         /* Create and allocate the fname structure */
367         len = sizeof(struct fname) + dirent->name_len + 1;
368         new_fn = kzalloc(len, GFP_KERNEL);
369         if (!new_fn)
370                 return -ENOMEM;
371         new_fn->hash = hash;
372         new_fn->minor_hash = minor_hash;
373         new_fn->inode = le32_to_cpu(dirent->inode);
374         new_fn->name_len = dirent->name_len;
375         new_fn->file_type = dirent->file_type;
376         memcpy(new_fn->name, dirent->name, dirent->name_len);
377         new_fn->name[dirent->name_len] = 0;
378
379         while (*p) {
380                 parent = *p;
381                 fname = rb_entry(parent, struct fname, rb_hash);
382
383                 /*
384                  * If the hash and minor hash match up, then we put
385                  * them on a linked list.  This rarely happens...
386                  */
387                 if ((new_fn->hash == fname->hash) &&
388                     (new_fn->minor_hash == fname->minor_hash)) {
389                         new_fn->next = fname->next;
390                         fname->next = new_fn;
391                         return 0;
392                 }
393
394                 if (new_fn->hash < fname->hash)
395                         p = &(*p)->rb_left;
396                 else if (new_fn->hash > fname->hash)
397                         p = &(*p)->rb_right;
398                 else if (new_fn->minor_hash < fname->minor_hash)
399                         p = &(*p)->rb_left;
400                 else /* if (new_fn->minor_hash > fname->minor_hash) */
401                         p = &(*p)->rb_right;
402         }
403
404         rb_link_node(&new_fn->rb_hash, parent, p);
405         rb_insert_color(&new_fn->rb_hash, &info->root);
406         return 0;
407 }
408
409
410
411 /*
412  * This is a helper function for ext4_dx_readdir.  It calls filldir
413  * for all entres on the fname linked list.  (Normally there is only
414  * one entry on the linked list, unless there are 62 bit hash collisions.)
415  */
416 static int call_filldir(struct file *filp, void *dirent,
417                         filldir_t filldir, struct fname *fname)
418 {
419         struct dir_private_info *info = filp->private_data;
420         loff_t  curr_pos;
421         struct inode *inode = filp->f_path.dentry->d_inode;
422         struct super_block *sb;
423         int error;
424
425         sb = inode->i_sb;
426
427         if (!fname) {
428                 printk(KERN_ERR "EXT4-fs: call_filldir: called with "
429                        "null fname?!?\n");
430                 return 0;
431         }
432         curr_pos = hash2pos(fname->hash, fname->minor_hash);
433         while (fname) {
434                 error = filldir(dirent, fname->name,
435                                 fname->name_len, curr_pos,
436                                 fname->inode,
437                                 get_dtype(sb, fname->file_type));
438                 if (error) {
439                         filp->f_pos = curr_pos;
440                         info->extra_fname = fname;
441                         return error;
442                 }
443                 fname = fname->next;
444         }
445         return 0;
446 }
447
448 static int ext4_dx_readdir(struct file *filp,
449                          void *dirent, filldir_t filldir)
450 {
451         struct dir_private_info *info = filp->private_data;
452         struct inode *inode = filp->f_path.dentry->d_inode;
453         struct fname *fname;
454         int     ret;
455
456         if (!info) {
457                 info = ext4_htree_create_dir_info(filp->f_pos);
458                 if (!info)
459                         return -ENOMEM;
460                 filp->private_data = info;
461         }
462
463         if (filp->f_pos == EXT4_HTREE_EOF)
464                 return 0;       /* EOF */
465
466         /* Some one has messed with f_pos; reset the world */
467         if (info->last_pos != filp->f_pos) {
468                 free_rb_tree_fname(&info->root);
469                 info->curr_node = NULL;
470                 info->extra_fname = NULL;
471                 info->curr_hash = pos2maj_hash(filp->f_pos);
472                 info->curr_minor_hash = pos2min_hash(filp->f_pos);
473         }
474
475         /*
476          * If there are any leftover names on the hash collision
477          * chain, return them first.
478          */
479         if (info->extra_fname) {
480                 if (call_filldir(filp, dirent, filldir, info->extra_fname))
481                         goto finished;
482                 info->extra_fname = NULL;
483                 goto next_node;
484         } else if (!info->curr_node)
485                 info->curr_node = rb_first(&info->root);
486
487         while (1) {
488                 /*
489                  * Fill the rbtree if we have no more entries,
490                  * or the inode has changed since we last read in the
491                  * cached entries.
492                  */
493                 if ((!info->curr_node) ||
494                     (filp->f_version != inode->i_version)) {
495                         info->curr_node = NULL;
496                         free_rb_tree_fname(&info->root);
497                         filp->f_version = inode->i_version;
498                         ret = ext4_htree_fill_tree(filp, info->curr_hash,
499                                                    info->curr_minor_hash,
500                                                    &info->next_hash);
501                         if (ret < 0)
502                                 return ret;
503                         if (ret == 0) {
504                                 filp->f_pos = EXT4_HTREE_EOF;
505                                 break;
506                         }
507                         info->curr_node = rb_first(&info->root);
508                 }
509
510                 fname = rb_entry(info->curr_node, struct fname, rb_hash);
511                 info->curr_hash = fname->hash;
512                 info->curr_minor_hash = fname->minor_hash;
513                 if (call_filldir(filp, dirent, filldir, fname))
514                         break;
515         next_node:
516                 info->curr_node = rb_next(info->curr_node);
517                 if (info->curr_node) {
518                         fname = rb_entry(info->curr_node, struct fname,
519                                          rb_hash);
520                         info->curr_hash = fname->hash;
521                         info->curr_minor_hash = fname->minor_hash;
522                 } else {
523                         if (info->next_hash == ~0) {
524                                 filp->f_pos = EXT4_HTREE_EOF;
525                                 break;
526                         }
527                         info->curr_hash = info->next_hash;
528                         info->curr_minor_hash = 0;
529                 }
530         }
531 finished:
532         info->last_pos = filp->f_pos;
533         return 0;
534 }
535
536 static int ext4_release_dir(struct inode *inode, struct file *filp)
537 {
538         if (filp->private_data)
539                 ext4_htree_free_dir_info(filp->private_data);
540
541         return 0;
542 }