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[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / fs / ext2 / dir.c
blob6cde970b0a1a04fae6b58aec7600491800078333
1 /*
2 * linux/fs/ext2/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 * ext2 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 * All code that works with directory layout had been switched to pagecache
21 * and moved here. AV
22 */
23
24 #include "ext2.h"
25 #include <linux/buffer_head.h>
26 #include <linux/pagemap.h>
27 #include <linux/swap.h>
28
29 typedef struct ext2_dir_entry_2 ext2_dirent;
30
31 static inline unsigned ext2_rec_len_from_disk(__le16 dlen)
32 {
33 unsigned len = le16_to_cpu(dlen);
34
35 if (len == EXT2_MAX_REC_LEN)
36 return 1 << 16;
37 return len;
38 }
39
40 static inline __le16 ext2_rec_len_to_disk(unsigned len)
41 {
42 if (len == (1 << 16))
43 return cpu_to_le16(EXT2_MAX_REC_LEN);
44 else
45 BUG_ON(len > (1 << 16));
46 return cpu_to_le16(len);
47 }
48
49 /*
50 * ext2 uses block-sized chunks. Arguably, sector-sized ones would be
51 * more robust, but we have what we have
52 */
53 static inline unsigned ext2_chunk_size(struct inode *inode)
54 {
55 return inode->i_sb->s_blocksize;
56 }
57
58 static inline void ext2_put_page(struct page *page)
59 {
60 kunmap(page);
61 page_cache_release(page);
62 }
63
64 static inline unsigned long dir_pages(struct inode *inode)
65 {
66 return (inode->i_size+PAGE_CACHE_SIZE-1)>>PAGE_CACHE_SHIFT;
67 }
68
69 /*
70 * Return the offset into page `page_nr' of the last valid
71 * byte in that page, plus one.
72 */
73 static unsigned
74 ext2_last_byte(struct inode *inode, unsigned long page_nr)
75 {
76 unsigned last_byte = inode->i_size;
77
78 last_byte -= page_nr << PAGE_CACHE_SHIFT;
79 if (last_byte > PAGE_CACHE_SIZE)
80 last_byte = PAGE_CACHE_SIZE;
81 return last_byte;
82 }
83
84 static int ext2_commit_chunk(struct page *page, loff_t pos, unsigned len)
85 {
86 struct address_space *mapping = page->mapping;
87 struct inode *dir = mapping->host;
88 int err = 0;
89
90 dir->i_version++;
91 block_write_end(NULL, mapping, pos, len, len, page, NULL);
92
93 if (pos+len > dir->i_size) {
94 i_size_write(dir, pos+len);
95 mark_inode_dirty(dir);
96 }
97
98 if (IS_DIRSYNC(dir)) {
99 err = write_one_page(page, 1);
100 if (!err)
101 err = ext2_sync_inode(dir);
102 } else {
103 unlock_page(page);
104 }
105
106 return err;
107 }
108
109 static void ext2_check_page(struct page *page, int quiet)
110 {
111 struct inode *dir = page->mapping->host;
112 struct super_block *sb = dir->i_sb;
113 unsigned chunk_size = ext2_chunk_size(dir);
114 char *kaddr = page_address(page);
115 u32 max_inumber = le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count);
116 unsigned offs, rec_len;
117 unsigned limit = PAGE_CACHE_SIZE;
118 ext2_dirent *p;
119 char *error;
120
121 if ((dir->i_size >> PAGE_CACHE_SHIFT) == page->index) {
122 limit = dir->i_size & ~PAGE_CACHE_MASK;
123 if (limit & (chunk_size - 1))
124 goto Ebadsize;
125 if (!limit)
126 goto out;
127 }
128 for (offs = 0; offs <= limit - EXT2_DIR_REC_LEN(1); offs += rec_len) {
129 p = (ext2_dirent *)(kaddr + offs);
130 rec_len = ext2_rec_len_from_disk(p->rec_len);
131
132 if (rec_len < EXT2_DIR_REC_LEN(1))
133 goto Eshort;
134 if (rec_len & 3)
135 goto Ealign;
136 if (rec_len < EXT2_DIR_REC_LEN(p->name_len))
137 goto Enamelen;
138 if (((offs + rec_len - 1) ^ offs) & ~(chunk_size-1))
139 goto Espan;
140 if (le32_to_cpu(p->inode) > max_inumber)
141 goto Einumber;
142 }
143 if (offs != limit)
144 goto Eend;
145 out:
146 SetPageChecked(page);
147 return;
148
149 /* Too bad, we had an error */
150
151 Ebadsize:
152 if (!quiet)
153 ext2_error(sb, __func__,
154 "size of directory #%lu is not a multiple "
155 "of chunk size", dir->i_ino);
156 goto fail;
157 Eshort:
158 error = "rec_len is smaller than minimal";
159 goto bad_entry;
160 Ealign:
161 error = "unaligned directory entry";
162 goto bad_entry;
163 Enamelen:
164 error = "rec_len is too small for name_len";
165 goto bad_entry;
166 Espan:
167 error = "directory entry across blocks";
168 goto bad_entry;
169 Einumber:
170 error = "inode out of bounds";
171 bad_entry:
172 if (!quiet)
173 ext2_error(sb, __func__, "bad entry in directory #%lu: : %s - "
174 "offset=%lu, inode=%lu, rec_len=%d, name_len=%d",
175 dir->i_ino, error, (page->index<<PAGE_CACHE_SHIFT)+offs,
176 (unsigned long) le32_to_cpu(p->inode),
177 rec_len, p->name_len);
178 goto fail;
179 Eend:
180 if (!quiet) {
181 p = (ext2_dirent *)(kaddr + offs);
182 ext2_error(sb, "ext2_check_page",
183 "entry in directory #%lu spans the page boundary"
184 "offset=%lu, inode=%lu",
185 dir->i_ino, (page->index<<PAGE_CACHE_SHIFT)+offs,
186 (unsigned long) le32_to_cpu(p->inode));
187 }
188 fail:
189 SetPageChecked(page);
190 SetPageError(page);
191 }
192
193 static struct page * ext2_get_page(struct inode *dir, unsigned long n,
194 int quiet)
195 {
196 struct address_space *mapping = dir->i_mapping;
197 struct page *page = read_mapping_page(mapping, n, NULL);
198 if (!IS_ERR(page)) {
199 kmap(page);
200 if (!PageChecked(page))
201 ext2_check_page(page, quiet);
202 if (PageError(page))
203 goto fail;
204 }
205 return page;
206
207 fail:
208 ext2_put_page(page);
209 return ERR_PTR(-EIO);
210 }
211
212 /*
213 * NOTE! unlike strncmp, ext2_match returns 1 for success, 0 for failure.
214 *
215 * len <= EXT2_NAME_LEN and de != NULL are guaranteed by caller.
216 */
217 static inline int ext2_match (int len, const char * const name,
218 struct ext2_dir_entry_2 * de)
219 {
220 if (len != de->name_len)
221 return 0;
222 if (!de->inode)
223 return 0;
224 return !memcmp(name, de->name, len);
225 }
226
227 /*
228 * p is at least 6 bytes before the end of page
229 */
230 static inline ext2_dirent *ext2_next_entry(ext2_dirent *p)
231 {
232 return (ext2_dirent *)((char *)p +
233 ext2_rec_len_from_disk(p->rec_len));
234 }
235
236 static inline unsigned
237 ext2_validate_entry(char *base, unsigned offset, unsigned mask)
238 {
239 ext2_dirent *de = (ext2_dirent*)(base + offset);
240 ext2_dirent *p = (ext2_dirent*)(base + (offset&mask));
241 while ((char*)p < (char*)de) {
242 if (p->rec_len == 0)
243 break;
244 p = ext2_next_entry(p);
245 }
246 return (char *)p - base;
247 }
248
249 static unsigned char ext2_filetype_table[EXT2_FT_MAX] = {
250 [EXT2_FT_UNKNOWN] = DT_UNKNOWN,
251 [EXT2_FT_REG_FILE] = DT_REG,
252 [EXT2_FT_DIR] = DT_DIR,
253 [EXT2_FT_CHRDEV] = DT_CHR,
254 [EXT2_FT_BLKDEV] = DT_BLK,
255 [EXT2_FT_FIFO] = DT_FIFO,
256 [EXT2_FT_SOCK] = DT_SOCK,
257 [EXT2_FT_SYMLINK] = DT_LNK,
258 };
259
260 #define S_SHIFT 12
261 static unsigned char ext2_type_by_mode[S_IFMT >> S_SHIFT] = {
262 [S_IFREG >> S_SHIFT] = EXT2_FT_REG_FILE,
263 [S_IFDIR >> S_SHIFT] = EXT2_FT_DIR,
264 [S_IFCHR >> S_SHIFT] = EXT2_FT_CHRDEV,
265 [S_IFBLK >> S_SHIFT] = EXT2_FT_BLKDEV,
266 [S_IFIFO >> S_SHIFT] = EXT2_FT_FIFO,
267 [S_IFSOCK >> S_SHIFT] = EXT2_FT_SOCK,
268 [S_IFLNK >> S_SHIFT] = EXT2_FT_SYMLINK,
269 };
270
271 static inline void ext2_set_de_type(ext2_dirent *de, struct inode *inode)
272 {
273 mode_t mode = inode->i_mode;
274 if (EXT2_HAS_INCOMPAT_FEATURE(inode->i_sb, EXT2_FEATURE_INCOMPAT_FILETYPE))
275 de->file_type = ext2_type_by_mode[(mode & S_IFMT)>>S_SHIFT];
276 else
277 de->file_type = 0;
278 }
279
280 static int
281 ext2_readdir (struct file * filp, void * dirent, filldir_t filldir)
282 {
283 loff_t pos = filp->f_pos;
284 struct inode *inode = filp->f_path.dentry->d_inode;
285 struct super_block *sb = inode->i_sb;
286 unsigned int offset = pos & ~PAGE_CACHE_MASK;
287 unsigned long n = pos >> PAGE_CACHE_SHIFT;
288 unsigned long npages = dir_pages(inode);
289 unsigned chunk_mask = ~(ext2_chunk_size(inode)-1);
290 unsigned char *types = NULL;
291 int need_revalidate = filp->f_version != inode->i_version;
292
293 if (pos > inode->i_size - EXT2_DIR_REC_LEN(1))
294 return 0;
295
296 if (EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_FILETYPE))
297 types = ext2_filetype_table;
298
299 for ( ; n < npages; n++, offset = 0) {
300 char *kaddr, *limit;
301 ext2_dirent *de;
302 struct page *page = ext2_get_page(inode, n, 0);
303
304 if (IS_ERR(page)) {
305 ext2_error(sb, __func__,
306 "bad page in #%lu",
307 inode->i_ino);
308 filp->f_pos += PAGE_CACHE_SIZE - offset;
309 return PTR_ERR(page);
310 }
311 kaddr = page_address(page);
312 if (unlikely(need_revalidate)) {
313 if (offset) {
314 offset = ext2_validate_entry(kaddr, offset, chunk_mask);
315 filp->f_pos = (n<<PAGE_CACHE_SHIFT) + offset;
316 }
317 filp->f_version = inode->i_version;
318 need_revalidate = 0;
319 }
320 de = (ext2_dirent *)(kaddr+offset);
321 limit = kaddr + ext2_last_byte(inode, n) - EXT2_DIR_REC_LEN(1);
322 for ( ;(char*)de <= limit; de = ext2_next_entry(de)) {
323 if (de->rec_len == 0) {
324 ext2_error(sb, __func__,
325 "zero-length directory entry");
326 ext2_put_page(page);
327 return -EIO;
328 }
329 if (de->inode) {
330 int over;
331 unsigned char d_type = DT_UNKNOWN;
332
333 if (types && de->file_type < EXT2_FT_MAX)
334 d_type = types[de->file_type];
335
336 offset = (char *)de - kaddr;
337 over = filldir(dirent, de->name, de->name_len,
338 (n<<PAGE_CACHE_SHIFT) | offset,
339 le32_to_cpu(de->inode), d_type);
340 if (over) {
341 ext2_put_page(page);
342 return 0;
343 }
344 }
345 filp->f_pos += ext2_rec_len_from_disk(de->rec_len);
346 }
347 ext2_put_page(page);
348 }
349 return 0;
350 }
351
352 /*
353 * ext2_find_entry()
354 *
355 * finds an entry in the specified directory with the wanted name. It
356 * returns the page in which the entry was found, and the entry itself
357 * (as a parameter - res_dir). Page is returned mapped and unlocked.
358 * Entry is guaranteed to be valid.
359 */
360 struct ext2_dir_entry_2 *ext2_find_entry (struct inode * dir,
361 struct qstr *child, struct page ** res_page)
362 {
363 const char *name = child->name;
364 int namelen = child->len;
365 unsigned reclen = EXT2_DIR_REC_LEN(namelen);
366 unsigned long start, n;
367 unsigned long npages = dir_pages(dir);
368 struct page *page = NULL;
369 struct ext2_inode_info *ei = EXT2_I(dir);
370 ext2_dirent * de;
371 int dir_has_error = 0;
372
373 if (npages == 0)
374 goto out;
375
376 /* OFFSET_CACHE */
377 *res_page = NULL;
378
379 start = ei->i_dir_start_lookup;
380 if (start >= npages)
381 start = 0;
382 n = start;
383 do {
384 char *kaddr;
385 page = ext2_get_page(dir, n, dir_has_error);
386 if (!IS_ERR(page)) {
387 kaddr = page_address(page);
388 de = (ext2_dirent *) kaddr;
389 kaddr += ext2_last_byte(dir, n) - reclen;
390 while ((char *) de <= kaddr) {
391 if (de->rec_len == 0) {
392 ext2_error(dir->i_sb, __func__,
393 "zero-length directory entry");
394 ext2_put_page(page);
395 goto out;
396 }
397 if (ext2_match (namelen, name, de))
398 goto found;
399 de = ext2_next_entry(de);
400 }
401 ext2_put_page(page);
402 } else
403 dir_has_error = 1;
404
405 if (++n >= npages)
406 n = 0;
407 /* next page is past the blocks we've got */
408 if (unlikely(n > (dir->i_blocks >> (PAGE_CACHE_SHIFT - 9)))) {
409 ext2_error(dir->i_sb, __func__,
410 "dir %lu size %lld exceeds block count %llu",
411 dir->i_ino, dir->i_size,
412 (unsigned long long)dir->i_blocks);
413 goto out;
414 }
415 } while (n != start);
416 out:
417 return NULL;
418
419 found:
420 *res_page = page;
421 ei->i_dir_start_lookup = n;
422 return de;
423 }
424
425 struct ext2_dir_entry_2 * ext2_dotdot (struct inode *dir, struct page **p)
426 {
427 struct page *page = ext2_get_page(dir, 0, 0);
428 ext2_dirent *de = NULL;
429
430 if (!IS_ERR(page)) {
431 de = ext2_next_entry((ext2_dirent *) page_address(page));
432 *p = page;
433 }
434 return de;
435 }
436
437 ino_t ext2_inode_by_name(struct inode *dir, struct qstr *child)
438 {
439 ino_t res = 0;
440 struct ext2_dir_entry_2 *de;
441 struct page *page;
442
443 de = ext2_find_entry (dir, child, &page);
444 if (de) {
445 res = le32_to_cpu(de->inode);
446 ext2_put_page(page);
447 }
448 return res;
449 }
450
451 /* Releases the page */
452 void ext2_set_link(struct inode *dir, struct ext2_dir_entry_2 *de,
453 struct page *page, struct inode *inode, int update_times)
454 {
455 loff_t pos = page_offset(page) +
456 (char *) de - (char *) page_address(page);
457 unsigned len = ext2_rec_len_from_disk(de->rec_len);
458 int err;
459
460 lock_page(page);
461 err = __ext2_write_begin(NULL, page->mapping, pos, len,
462 AOP_FLAG_UNINTERRUPTIBLE, &page, NULL);
463 BUG_ON(err);
464 de->inode = cpu_to_le32(inode->i_ino);
465 ext2_set_de_type(de, inode);
466 err = ext2_commit_chunk(page, pos, len);
467 ext2_put_page(page);
468 if (update_times)
469 dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
470 EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL;
471 mark_inode_dirty(dir);
472 }
473
474 /*
475 * Parent is locked.
476 */
477 int ext2_add_link (struct dentry *dentry, struct inode *inode)
478 {
479 struct inode *dir = dentry->d_parent->d_inode;
480 const char *name = dentry->d_name.name;
481 int namelen = dentry->d_name.len;
482 unsigned chunk_size = ext2_chunk_size(dir);
483 unsigned reclen = EXT2_DIR_REC_LEN(namelen);
484 unsigned short rec_len, name_len;
485 struct page *page = NULL;
486 ext2_dirent * de;
487 unsigned long npages = dir_pages(dir);
488 unsigned long n;
489 char *kaddr;
490 loff_t pos;
491 int err;
492
493 /*
494 * We take care of directory expansion in the same loop.
495 * This code plays outside i_size, so it locks the page
496 * to protect that region.
497 */
498 for (n = 0; n <= npages; n++) {
499 char *dir_end;
500
501 page = ext2_get_page(dir, n, 0);
502 err = PTR_ERR(page);
503 if (IS_ERR(page))
504 goto out;
505 lock_page(page);
506 kaddr = page_address(page);
507 dir_end = kaddr + ext2_last_byte(dir, n);
508 de = (ext2_dirent *)kaddr;
509 kaddr += PAGE_CACHE_SIZE - reclen;
510 while ((char *)de <= kaddr) {
511 if ((char *)de == dir_end) {
512 /* We hit i_size */
513 name_len = 0;
514 rec_len = chunk_size;
515 de->rec_len = ext2_rec_len_to_disk(chunk_size);
516 de->inode = 0;
517 goto got_it;
518 }
519 if (de->rec_len == 0) {
520 ext2_error(dir->i_sb, __func__,
521 "zero-length directory entry");
522 err = -EIO;
523 goto out_unlock;
524 }
525 err = -EEXIST;
526 if (ext2_match (namelen, name, de))
527 goto out_unlock;
528 name_len = EXT2_DIR_REC_LEN(de->name_len);
529 rec_len = ext2_rec_len_from_disk(de->rec_len);
530 if (!de->inode && rec_len >= reclen)
531 goto got_it;
532 if (rec_len >= name_len + reclen)
533 goto got_it;
534 de = (ext2_dirent *) ((char *) de + rec_len);
535 }
536 unlock_page(page);
537 ext2_put_page(page);
538 }
539 BUG();
540 return -EINVAL;
541
542 got_it:
543 pos = page_offset(page) +
544 (char*)de - (char*)page_address(page);
545 err = __ext2_write_begin(NULL, page->mapping, pos, rec_len, 0,
546 &page, NULL);
547 if (err)
548 goto out_unlock;
549 if (de->inode) {
550 ext2_dirent *de1 = (ext2_dirent *) ((char *) de + name_len);
551 de1->rec_len = ext2_rec_len_to_disk(rec_len - name_len);
552 de->rec_len = ext2_rec_len_to_disk(name_len);
553 de = de1;
554 }
555 de->name_len = namelen;
556 memcpy(de->name, name, namelen);
557 de->inode = cpu_to_le32(inode->i_ino);
558 ext2_set_de_type (de, inode);
559 err = ext2_commit_chunk(page, pos, rec_len);
560 dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
561 EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL;
562 mark_inode_dirty(dir);
563 /* OFFSET_CACHE */
564 out_put:
565 ext2_put_page(page);
566 out:
567 return err;
568 out_unlock:
569 unlock_page(page);
570 goto out_put;
571 }
572
573 /*
574 * ext2_delete_entry deletes a directory entry by merging it with the
575 * previous entry. Page is up-to-date. Releases the page.
576 */
577 int ext2_delete_entry (struct ext2_dir_entry_2 * dir, struct page * page )
578 {
579 struct address_space *mapping = page->mapping;
580 struct inode *inode = mapping->host;
581 char *kaddr = page_address(page);
582 unsigned from = ((char*)dir - kaddr) & ~(ext2_chunk_size(inode)-1);
583 unsigned to = ((char *)dir - kaddr) +
584 ext2_rec_len_from_disk(dir->rec_len);
585 loff_t pos;
586 ext2_dirent * pde = NULL;
587 ext2_dirent * de = (ext2_dirent *) (kaddr + from);
588 int err;
589
590 while ((char*)de < (char*)dir) {
591 if (de->rec_len == 0) {
592 ext2_error(inode->i_sb, __func__,
593 "zero-length directory entry");
594 err = -EIO;
595 goto out;
596 }
597 pde = de;
598 de = ext2_next_entry(de);
599 }
600 if (pde)
601 from = (char*)pde - (char*)page_address(page);
602 pos = page_offset(page) + from;
603 lock_page(page);
604 err = __ext2_write_begin(NULL, page->mapping, pos, to - from, 0,
605 &page, NULL);
606 BUG_ON(err);
607 if (pde)
608 pde->rec_len = ext2_rec_len_to_disk(to - from);
609 dir->inode = 0;
610 err = ext2_commit_chunk(page, pos, to - from);
611 inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
612 EXT2_I(inode)->i_flags &= ~EXT2_BTREE_FL;
613 mark_inode_dirty(inode);
614 out:
615 ext2_put_page(page);
616 return err;
617 }
618
619 /*
620 * Set the first fragment of directory.
621 */
622 int ext2_make_empty(struct inode *inode, struct inode *parent)
623 {
624 struct address_space *mapping = inode->i_mapping;
625 struct page *page = grab_cache_page(mapping, 0);
626 unsigned chunk_size = ext2_chunk_size(inode);
627 struct ext2_dir_entry_2 * de;
628 int err;
629 void *kaddr;
630
631 if (!page)
632 return -ENOMEM;
633
634 err = __ext2_write_begin(NULL, page->mapping, 0, chunk_size, 0,
635 &page, NULL);
636 if (err) {
637 unlock_page(page);
638 goto fail;
639 }
640 kaddr = kmap_atomic(page, KM_USER0);
641 memset(kaddr, 0, chunk_size);
642 de = (struct ext2_dir_entry_2 *)kaddr;
643 de->name_len = 1;
644 de->rec_len = ext2_rec_len_to_disk(EXT2_DIR_REC_LEN(1));
645 memcpy (de->name, ".\0\0", 4);
646 de->inode = cpu_to_le32(inode->i_ino);
647 ext2_set_de_type (de, inode);
648
649 de = (struct ext2_dir_entry_2 *)(kaddr + EXT2_DIR_REC_LEN(1));
650 de->name_len = 2;
651 de->rec_len = ext2_rec_len_to_disk(chunk_size - EXT2_DIR_REC_LEN(1));
652 de->inode = cpu_to_le32(parent->i_ino);
653 memcpy (de->name, "..\0", 4);
654 ext2_set_de_type (de, inode);
655 kunmap_atomic(kaddr, KM_USER0);
656 err = ext2_commit_chunk(page, 0, chunk_size);
657 fail:
658 page_cache_release(page);
659 return err;
660 }
661
662 /*
663 * routine to check that the specified directory is empty (for rmdir)
664 */
665 int ext2_empty_dir (struct inode * inode)
666 {
667 struct page *page = NULL;
668 unsigned long i, npages = dir_pages(inode);
669 int dir_has_error = 0;
670
671 for (i = 0; i < npages; i++) {
672 char *kaddr;
673 ext2_dirent * de;
674 page = ext2_get_page(inode, i, dir_has_error);
675
676 if (IS_ERR(page)) {
677 dir_has_error = 1;
678 continue;
679 }
680
681 kaddr = page_address(page);
682 de = (ext2_dirent *)kaddr;
683 kaddr += ext2_last_byte(inode, i) - EXT2_DIR_REC_LEN(1);
684
685 while ((char *)de <= kaddr) {
686 if (de->rec_len == 0) {
687 ext2_error(inode->i_sb, __func__,
688 "zero-length directory entry");
689 printk("kaddr=%p, de=%p\n", kaddr, de);
690 goto not_empty;
691 }
692 if (de->inode != 0) {
693 /* check for . and .. */
694 if (de->name[0] != '.')
695 goto not_empty;
696 if (de->name_len > 2)
697 goto not_empty;
698 if (de->name_len < 2) {
699 if (de->inode !=
700 cpu_to_le32(inode->i_ino))
701 goto not_empty;
702 } else if (de->name[1] != '.')
703 goto not_empty;
704 }
705 de = ext2_next_entry(de);
706 }
707 ext2_put_page(page);
708 }
709 return 1;
710
711 not_empty:
712 ext2_put_page(page);
713 return 0;
714 }
715
716 const struct file_operations ext2_dir_operations = {
717 .llseek = generic_file_llseek,
718 .read = generic_read_dir,
719 .readdir = ext2_readdir,
720 .unlocked_ioctl = ext2_ioctl,
721 #ifdef CONFIG_COMPAT
722 .compat_ioctl = ext2_compat_ioctl,
723 #endif
724 .fsync = simple_fsync,
725 };
Linux 2.6 ibm-acpi/thinkpad-acpi driver git tree