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
get_dtype(struct super_block * sb,int filetype)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 */
is_dx_dir(struct inode * inode)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
ext3_check_dir_entry(const char * function,struct inode * dir,struct ext3_dir_entry_2 * de,struct buffer_head * bh,unsigned long offset)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
ext3_readdir(struct file * filp,void * dirent,filldir_t filldir)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 = file_inode(filp);
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(file_inode(filp))->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
is_32bit_api(void)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 */
hash2pos(struct file * filp,__u32 major,__u32 minor)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
pos2maj_hash(struct file * filp,loff_t pos)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
pos2min_hash(struct file * filp,loff_t pos)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 */
ext3_get_htree_eof(struct file * filp)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 */
ext3_dir_llseek(struct file * file,loff_t offset,int whence)299 loff_t ext3_dir_llseek(struct file *file, loff_t offset, int whence)
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, whence,
307 htree_max, htree_max);
308 else
309 return generic_file_llseek(file, offset, whence);
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 {
317 __u32 hash;
318 __u32 minor_hash;
319 struct rb_node rb_hash;
320 struct fname *next;
321 __u32 inode;
322 __u8 name_len;
323 __u8 file_type;
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 */
free_rb_tree_fname(struct rb_root * root)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
ext3_htree_create_dir_info(struct file * filp,loff_t pos)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
ext3_htree_free_dir_info(struct dir_private_info * p)384 void ext3_htree_free_dir_info(struct dir_private_info *p)
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 */
ext3_htree_store_dirent(struct file * dir_file,__u32 hash,__u32 minor_hash,struct ext3_dir_entry_2 * dirent)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 */
call_filldir(struct file * filp,void * dirent,filldir_t filldir,struct fname * fname)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 = file_inode(filp);
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
ext3_dx_readdir(struct file * filp,void * dirent,filldir_t filldir)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 = file_inode(filp);
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
ext3_release_dir(struct inode * inode,struct file * filp)574 static int ext3_release_dir (struct inode * inode, struct file * filp)
575 {
576 if (filp->private_data)
577 ext3_htree_free_dir_info(filp->private_data);
578
579 return 0;
580 }
581
582 const struct file_operations ext3_dir_operations = {
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 };
593