832867aef3dca61d8d2376e9ca7e14a24dbafd69
[linux-2.6.git] / fs / ext3 / dir.c
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/fs.h>
25 #include <linux/jbd.h>
26 #include <linux/ext3_fs.h>
27 #include <linux/buffer_head.h>
28 #include <linux/smp_lock.h>
29 #include <linux/slab.h>
30 #include <linux/rbtree.h>
31
32 static unsigned char ext3_filetype_table[] = {
33         DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK, DT_FIFO, DT_SOCK, DT_LNK
34 };
35
36 static int ext3_readdir(struct file *, void *, filldir_t);
37 static int ext3_dx_readdir(struct file * filp,
38                            void * dirent, filldir_t filldir);
39 static int ext3_release_dir (struct inode * inode,
40                                 struct file * filp);
41
42 struct file_operations ext3_dir_operations = {
43         .llseek         = generic_file_llseek,
44         .read           = generic_read_dir,
45         .readdir        = ext3_readdir,         /* we take BKL. needed?*/
46         .ioctl          = ext3_ioctl,           /* BKL held */
47         .fsync          = ext3_sync_file,       /* BKL held */
48 #ifdef CONFIG_EXT3_INDEX
49         .release        = ext3_release_dir,
50 #endif
51 };
52
53
54 static unsigned char get_dtype(struct super_block *sb, int filetype)
55 {
56         if (!EXT3_HAS_INCOMPAT_FEATURE(sb, EXT3_FEATURE_INCOMPAT_FILETYPE) ||
57             (filetype >= EXT3_FT_MAX))
58                 return DT_UNKNOWN;
59
60         return (ext3_filetype_table[filetype]);
61 }
62                                
63
64 int ext3_check_dir_entry (const char * function, struct inode * dir,
65                           struct ext3_dir_entry_2 * de,
66                           struct buffer_head * bh,
67                           unsigned long offset)
68 {
69         const char * error_msg = NULL;
70         const int rlen = le16_to_cpu(de->rec_len);
71
72         if (rlen < EXT3_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 < EXT3_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(EXT3_SB(dir->i_sb)->s_es->s_inodes_count))
82                 error_msg = "inode out of bounds";
83
84         if (error_msg != NULL)
85                 ext3_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 ext3_readdir(struct file * filp,
95                          void * dirent, filldir_t filldir)
96 {
97         int error = 0;
98         unsigned long offset, blk;
99         int i, num, stored;
100         struct buffer_head * bh, * tmp, * bha[16];
101         struct ext3_dir_entry_2 * de;
102         struct super_block * sb;
103         int err;
104         struct inode *inode = filp->f_dentry->d_inode;
105         int ret = 0;
106
107         sb = inode->i_sb;
108
109 #ifdef CONFIG_EXT3_INDEX
110         if (EXT3_HAS_COMPAT_FEATURE(inode->i_sb,
111                                     EXT3_FEATURE_COMPAT_DIR_INDEX) &&
112             ((EXT3_I(inode)->i_flags & EXT3_INDEX_FL) ||
113              ((inode->i_size >> sb->s_blocksize_bits) == 1))) {
114                 err = ext3_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                 EXT3_I(filp->f_dentry->d_inode)->i_flags &= ~EXT3_INDEX_FL;
124         }
125 #endif
126         stored = 0;
127         bh = NULL;
128         offset = filp->f_pos & (sb->s_blocksize - 1);
129
130         while (!error && !stored && filp->f_pos < inode->i_size) {
131                 blk = (filp->f_pos) >> EXT3_BLOCK_SIZE_BITS(sb);
132                 bh = ext3_bread(NULL, inode, blk, 0, &err);
133                 if (!bh) {
134                         ext3_error (sb, "ext3_readdir",
135                                 "directory #%lu contains a hole at offset %lu",
136                                 inode->i_ino, (unsigned long)filp->f_pos);
137                         filp->f_pos += sb->s_blocksize - offset;
138                         continue;
139                 }
140
141                 /*
142                  * Do the readahead
143                  */
144                 if (!offset) {
145                         for (i = 16 >> (EXT3_BLOCK_SIZE_BITS(sb) - 9), num = 0;
146                              i > 0; i--) {
147                                 tmp = ext3_getblk (NULL, inode, ++blk, 0, &err);
148                                 if (tmp && !buffer_uptodate(tmp) &&
149                                                 !buffer_locked(tmp))
150                                         bha[num++] = tmp;
151                                 else
152                                         brelse (tmp);
153                         }
154                         if (num) {
155                                 ll_rw_block (READA, num, bha);
156                                 for (i = 0; i < num; i++)
157                                         brelse (bha[i]);
158                         }
159                 }
160
161 revalidate:
162                 /* If the dir block has changed since the last call to
163                  * readdir(2), then we might be pointing to an invalid
164                  * dirent right now.  Scan from the start of the block
165                  * to make sure. */
166                 if (filp->f_version != inode->i_version) {
167                         for (i = 0; i < sb->s_blocksize && i < offset; ) {
168                                 de = (struct ext3_dir_entry_2 *) 
169                                         (bh->b_data + i);
170                                 /* It's too expensive to do a full
171                                  * dirent test each time round this
172                                  * loop, but we do have to test at
173                                  * least that it is non-zero.  A
174                                  * failure will be detected in the
175                                  * dirent test below. */
176                                 if (le16_to_cpu(de->rec_len) <
177                                                 EXT3_DIR_REC_LEN(1))
178                                         break;
179                                 i += le16_to_cpu(de->rec_len);
180                         }
181                         offset = i;
182                         filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1))
183                                 | offset;
184                         filp->f_version = inode->i_version;
185                 }
186
187                 while (!error && filp->f_pos < inode->i_size 
188                        && offset < sb->s_blocksize) {
189                         de = (struct ext3_dir_entry_2 *) (bh->b_data + offset);
190                         if (!ext3_check_dir_entry ("ext3_readdir", inode, de,
191                                                    bh, offset)) {
192                                 /* On error, skip the f_pos to the
193                                    next block. */
194                                 filp->f_pos = (filp->f_pos |
195                                                 (sb->s_blocksize - 1)) + 1;
196                                 brelse (bh);
197                                 ret = stored;
198                                 goto out;
199                         }
200                         offset += le16_to_cpu(de->rec_len);
201                         if (le32_to_cpu(de->inode)) {
202                                 /* We might block in the next section
203                                  * if the data destination is
204                                  * currently swapped out.  So, use a
205                                  * version stamp to detect whether or
206                                  * not the directory has been modified
207                                  * during the copy operation.
208                                  */
209                                 unsigned long version = filp->f_version;
210
211                                 error = filldir(dirent, de->name,
212                                                 de->name_len,
213                                                 filp->f_pos,
214                                                 le32_to_cpu(de->inode),
215                                                 get_dtype(sb, de->file_type));
216                                 if (error)
217                                         break;
218                                 if (version != filp->f_version)
219                                         goto revalidate;
220                                 stored ++;
221                         }
222                         filp->f_pos += le16_to_cpu(de->rec_len);
223                 }
224                 offset = 0;
225                 brelse (bh);
226         }
227 out:
228         return ret;
229 }
230
231 #ifdef CONFIG_EXT3_INDEX
232 /*
233  * These functions convert from the major/minor hash to an f_pos
234  * value.
235  * 
236  * Currently we only use major hash numer.  This is unfortunate, but
237  * on 32-bit machines, the same VFS interface is used for lseek and
238  * llseek, so if we use the 64 bit offset, then the 32-bit versions of
239  * lseek/telldir/seekdir will blow out spectacularly, and from within
240  * the ext2 low-level routine, we don't know if we're being called by
241  * a 64-bit version of the system call or the 32-bit version of the
242  * system call.  Worse yet, NFSv2 only allows for a 32-bit readdir
243  * cookie.  Sigh.
244  */
245 #define hash2pos(major, minor)  (major >> 1)
246 #define pos2maj_hash(pos)       ((pos << 1) & 0xffffffff)
247 #define pos2min_hash(pos)       (0)
248
249 /*
250  * This structure holds the nodes of the red-black tree used to store
251  * the directory entry in hash order.
252  */
253 struct fname {
254         __u32           hash;
255         __u32           minor_hash;
256         struct rb_node  rb_hash; 
257         struct fname    *next;
258         __u32           inode;
259         __u8            name_len;
260         __u8            file_type;
261         char            name[0];
262 };
263
264 /*
265  * This functoin implements a non-recursive way of freeing all of the
266  * nodes in the red-black tree.
267  */
268 static void free_rb_tree_fname(struct rb_root *root)
269 {
270         struct rb_node  *n = root->rb_node;
271         struct rb_node  *parent;
272         struct fname    *fname;
273
274         while (n) {
275                 /* Do the node's children first */
276                 if ((n)->rb_left) {
277                         n = n->rb_left;
278                         continue;
279                 }
280                 if (n->rb_right) {
281                         n = n->rb_right;
282                         continue;
283                 }
284                 /*
285                  * The node has no children; free it, and then zero
286                  * out parent's link to it.  Finally go to the
287                  * beginning of the loop and try to free the parent
288                  * node.
289                  */
290                 parent = n->rb_parent;
291                 fname = rb_entry(n, struct fname, rb_hash);
292                 while (fname) {
293                         struct fname * old = fname;
294                         fname = fname->next;
295                         kfree (old);
296                 }
297                 if (!parent)
298                         root->rb_node = NULL;
299                 else if (parent->rb_left == n)
300                         parent->rb_left = NULL;
301                 else if (parent->rb_right == n)
302                         parent->rb_right = NULL;
303                 n = parent;
304         }
305         root->rb_node = NULL;
306 }
307
308
309 static struct dir_private_info *create_dir_info(loff_t pos)
310 {
311         struct dir_private_info *p;
312
313         p = kmalloc(sizeof(struct dir_private_info), GFP_KERNEL);
314         if (!p)
315                 return NULL;
316         p->root.rb_node = NULL;
317         p->curr_node = NULL;
318         p->extra_fname = NULL;
319         p->last_pos = 0;
320         p->curr_hash = pos2maj_hash(pos);
321         p->curr_minor_hash = pos2min_hash(pos);
322         p->next_hash = 0;
323         return p;
324 }
325
326 void ext3_htree_free_dir_info(struct dir_private_info *p)
327 {
328         free_rb_tree_fname(&p->root);
329         kfree(p);
330 }
331
332 /*
333  * Given a directory entry, enter it into the fname rb tree.
334  */
335 int ext3_htree_store_dirent(struct file *dir_file, __u32 hash,
336                              __u32 minor_hash,
337                              struct ext3_dir_entry_2 *dirent)
338 {
339         struct rb_node **p, *parent = NULL;
340         struct fname * fname, *new_fn;
341         struct dir_private_info *info;
342         int len;
343
344         info = (struct dir_private_info *) dir_file->private_data;
345         p = &info->root.rb_node;
346
347         /* Create and allocate the fname structure */
348         len = sizeof(struct fname) + dirent->name_len + 1;
349         new_fn = kmalloc(len, GFP_KERNEL);
350         if (!new_fn)
351                 return -ENOMEM;
352         memset(new_fn, 0, len);
353         new_fn->hash = hash;
354         new_fn->minor_hash = minor_hash;
355         new_fn->inode = le32_to_cpu(dirent->inode);
356         new_fn->name_len = dirent->name_len;
357         new_fn->file_type = dirent->file_type;
358         memcpy(new_fn->name, dirent->name, dirent->name_len);
359         new_fn->name[dirent->name_len] = 0;
360
361         while (*p) {
362                 parent = *p;
363                 fname = rb_entry(parent, struct fname, rb_hash);
364
365                 /*
366                  * If the hash and minor hash match up, then we put
367                  * them on a linked list.  This rarely happens...
368                  */
369                 if ((new_fn->hash == fname->hash) &&
370                     (new_fn->minor_hash == fname->minor_hash)) {
371                         new_fn->next = fname->next;
372                         fname->next = new_fn;
373                         return 0;
374                 }
375
376                 if (new_fn->hash < fname->hash)
377                         p = &(*p)->rb_left;
378                 else if (new_fn->hash > fname->hash)
379                         p = &(*p)->rb_right;
380                 else if (new_fn->minor_hash < fname->minor_hash)
381                         p = &(*p)->rb_left;
382                 else /* if (new_fn->minor_hash > fname->minor_hash) */
383                         p = &(*p)->rb_right;
384         }
385
386         rb_link_node(&new_fn->rb_hash, parent, p);
387         rb_insert_color(&new_fn->rb_hash, &info->root);
388         return 0;
389 }
390
391
392
393 /*
394  * This is a helper function for ext3_dx_readdir.  It calls filldir
395  * for all entres on the fname linked list.  (Normally there is only
396  * one entry on the linked list, unless there are 62 bit hash collisions.)
397  */
398 static int call_filldir(struct file * filp, void * dirent,
399                         filldir_t filldir, struct fname *fname)
400 {
401         struct dir_private_info *info = filp->private_data;
402         loff_t  curr_pos;
403         struct inode *inode = filp->f_dentry->d_inode;
404         struct super_block * sb;
405         int error;
406
407         sb = inode->i_sb;
408
409         if (!fname) {
410                 printk("call_filldir: called with null fname?!?\n");
411                 return 0;
412         }
413         curr_pos = hash2pos(fname->hash, fname->minor_hash);
414         while (fname) {
415                 error = filldir(dirent, fname->name,
416                                 fname->name_len, curr_pos, 
417                                 fname->inode,
418                                 get_dtype(sb, fname->file_type));
419                 if (error) {
420                         filp->f_pos = curr_pos;
421                         info->extra_fname = fname->next;
422                         return error;
423                 }
424                 fname = fname->next;
425         }
426         return 0;
427 }
428
429 static int ext3_dx_readdir(struct file * filp,
430                          void * dirent, filldir_t filldir)
431 {
432         struct dir_private_info *info = filp->private_data;
433         struct inode *inode = filp->f_dentry->d_inode;
434         struct fname *fname;
435         int     ret;
436
437         if (!info) {
438                 info = create_dir_info(filp->f_pos);
439                 if (!info)
440                         return -ENOMEM;
441                 filp->private_data = info;
442         }
443
444         if (filp->f_pos == EXT3_HTREE_EOF)
445                 return 0;       /* EOF */
446
447         /* Some one has messed with f_pos; reset the world */
448         if (info->last_pos != filp->f_pos) {
449                 free_rb_tree_fname(&info->root);
450                 info->curr_node = NULL;
451                 info->extra_fname = NULL;
452                 info->curr_hash = pos2maj_hash(filp->f_pos);
453                 info->curr_minor_hash = pos2min_hash(filp->f_pos);
454         }
455
456         /*
457          * If there are any leftover names on the hash collision
458          * chain, return them first.
459          */
460         if (info->extra_fname &&
461             call_filldir(filp, dirent, filldir, info->extra_fname))
462                 goto finished;
463
464         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 = ext3_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 = EXT3_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
496                 info->curr_node = rb_next(info->curr_node);
497                 if (!info->curr_node) {
498                         if (info->next_hash == ~0) {
499                                 filp->f_pos = EXT3_HTREE_EOF;
500                                 break;
501                         }
502                         info->curr_hash = info->next_hash;
503                         info->curr_minor_hash = 0;
504                 }
505         }
506 finished:
507         info->last_pos = filp->f_pos;
508         return 0;
509 }
510
511 static int ext3_release_dir (struct inode * inode, struct file * filp)
512 {
513        if (filp->private_data)
514                 ext3_htree_free_dir_info(filp->private_data);
515
516         return 0;
517 }
518
519 #endif