xref: /openbmc/linux/fs/ext2/dir.c (revision e868d61272caa648214046a096e5a6bfc068dc8c)
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/pagemap.h>
26 
27 typedef struct ext2_dir_entry_2 ext2_dirent;
28 
29 /*
30  * ext2 uses block-sized chunks. Arguably, sector-sized ones would be
31  * more robust, but we have what we have
32  */
33 static inline unsigned ext2_chunk_size(struct inode *inode)
34 {
35 	return inode->i_sb->s_blocksize;
36 }
37 
38 static inline void ext2_put_page(struct page *page)
39 {
40 	kunmap(page);
41 	page_cache_release(page);
42 }
43 
44 static inline unsigned long dir_pages(struct inode *inode)
45 {
46 	return (inode->i_size+PAGE_CACHE_SIZE-1)>>PAGE_CACHE_SHIFT;
47 }
48 
49 /*
50  * Return the offset into page `page_nr' of the last valid
51  * byte in that page, plus one.
52  */
53 static unsigned
54 ext2_last_byte(struct inode *inode, unsigned long page_nr)
55 {
56 	unsigned last_byte = inode->i_size;
57 
58 	last_byte -= page_nr << PAGE_CACHE_SHIFT;
59 	if (last_byte > PAGE_CACHE_SIZE)
60 		last_byte = PAGE_CACHE_SIZE;
61 	return last_byte;
62 }
63 
64 static int ext2_commit_chunk(struct page *page, unsigned from, unsigned to)
65 {
66 	struct inode *dir = page->mapping->host;
67 	int err = 0;
68 	dir->i_version++;
69 	page->mapping->a_ops->commit_write(NULL, page, from, to);
70 	if (IS_DIRSYNC(dir))
71 		err = write_one_page(page, 1);
72 	else
73 		unlock_page(page);
74 	return err;
75 }
76 
77 static void ext2_check_page(struct page *page)
78 {
79 	struct inode *dir = page->mapping->host;
80 	struct super_block *sb = dir->i_sb;
81 	unsigned chunk_size = ext2_chunk_size(dir);
82 	char *kaddr = page_address(page);
83 	u32 max_inumber = le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count);
84 	unsigned offs, rec_len;
85 	unsigned limit = PAGE_CACHE_SIZE;
86 	ext2_dirent *p;
87 	char *error;
88 
89 	if ((dir->i_size >> PAGE_CACHE_SHIFT) == page->index) {
90 		limit = dir->i_size & ~PAGE_CACHE_MASK;
91 		if (limit & (chunk_size - 1))
92 			goto Ebadsize;
93 		if (!limit)
94 			goto out;
95 	}
96 	for (offs = 0; offs <= limit - EXT2_DIR_REC_LEN(1); offs += rec_len) {
97 		p = (ext2_dirent *)(kaddr + offs);
98 		rec_len = le16_to_cpu(p->rec_len);
99 
100 		if (rec_len < EXT2_DIR_REC_LEN(1))
101 			goto Eshort;
102 		if (rec_len & 3)
103 			goto Ealign;
104 		if (rec_len < EXT2_DIR_REC_LEN(p->name_len))
105 			goto Enamelen;
106 		if (((offs + rec_len - 1) ^ offs) & ~(chunk_size-1))
107 			goto Espan;
108 		if (le32_to_cpu(p->inode) > max_inumber)
109 			goto Einumber;
110 	}
111 	if (offs != limit)
112 		goto Eend;
113 out:
114 	SetPageChecked(page);
115 	return;
116 
117 	/* Too bad, we had an error */
118 
119 Ebadsize:
120 	ext2_error(sb, "ext2_check_page",
121 		"size of directory #%lu is not a multiple of chunk size",
122 		dir->i_ino
123 	);
124 	goto fail;
125 Eshort:
126 	error = "rec_len is smaller than minimal";
127 	goto bad_entry;
128 Ealign:
129 	error = "unaligned directory entry";
130 	goto bad_entry;
131 Enamelen:
132 	error = "rec_len is too small for name_len";
133 	goto bad_entry;
134 Espan:
135 	error = "directory entry across blocks";
136 	goto bad_entry;
137 Einumber:
138 	error = "inode out of bounds";
139 bad_entry:
140 	ext2_error (sb, "ext2_check_page", "bad entry in directory #%lu: %s - "
141 		"offset=%lu, inode=%lu, rec_len=%d, name_len=%d",
142 		dir->i_ino, error, (page->index<<PAGE_CACHE_SHIFT)+offs,
143 		(unsigned long) le32_to_cpu(p->inode),
144 		rec_len, p->name_len);
145 	goto fail;
146 Eend:
147 	p = (ext2_dirent *)(kaddr + offs);
148 	ext2_error (sb, "ext2_check_page",
149 		"entry in directory #%lu spans the page boundary"
150 		"offset=%lu, inode=%lu",
151 		dir->i_ino, (page->index<<PAGE_CACHE_SHIFT)+offs,
152 		(unsigned long) le32_to_cpu(p->inode));
153 fail:
154 	SetPageChecked(page);
155 	SetPageError(page);
156 }
157 
158 static struct page * ext2_get_page(struct inode *dir, unsigned long n)
159 {
160 	struct address_space *mapping = dir->i_mapping;
161 	struct page *page = read_mapping_page(mapping, n, NULL);
162 	if (!IS_ERR(page)) {
163 		kmap(page);
164 		if (!PageChecked(page))
165 			ext2_check_page(page);
166 		if (PageError(page))
167 			goto fail;
168 	}
169 	return page;
170 
171 fail:
172 	ext2_put_page(page);
173 	return ERR_PTR(-EIO);
174 }
175 
176 /*
177  * NOTE! unlike strncmp, ext2_match returns 1 for success, 0 for failure.
178  *
179  * len <= EXT2_NAME_LEN and de != NULL are guaranteed by caller.
180  */
181 static inline int ext2_match (int len, const char * const name,
182 					struct ext2_dir_entry_2 * de)
183 {
184 	if (len != de->name_len)
185 		return 0;
186 	if (!de->inode)
187 		return 0;
188 	return !memcmp(name, de->name, len);
189 }
190 
191 /*
192  * p is at least 6 bytes before the end of page
193  */
194 static inline ext2_dirent *ext2_next_entry(ext2_dirent *p)
195 {
196 	return (ext2_dirent *)((char*)p + le16_to_cpu(p->rec_len));
197 }
198 
199 static inline unsigned
200 ext2_validate_entry(char *base, unsigned offset, unsigned mask)
201 {
202 	ext2_dirent *de = (ext2_dirent*)(base + offset);
203 	ext2_dirent *p = (ext2_dirent*)(base + (offset&mask));
204 	while ((char*)p < (char*)de) {
205 		if (p->rec_len == 0)
206 			break;
207 		p = ext2_next_entry(p);
208 	}
209 	return (char *)p - base;
210 }
211 
212 static unsigned char ext2_filetype_table[EXT2_FT_MAX] = {
213 	[EXT2_FT_UNKNOWN]	= DT_UNKNOWN,
214 	[EXT2_FT_REG_FILE]	= DT_REG,
215 	[EXT2_FT_DIR]		= DT_DIR,
216 	[EXT2_FT_CHRDEV]	= DT_CHR,
217 	[EXT2_FT_BLKDEV]	= DT_BLK,
218 	[EXT2_FT_FIFO]		= DT_FIFO,
219 	[EXT2_FT_SOCK]		= DT_SOCK,
220 	[EXT2_FT_SYMLINK]	= DT_LNK,
221 };
222 
223 #define S_SHIFT 12
224 static unsigned char ext2_type_by_mode[S_IFMT >> S_SHIFT] = {
225 	[S_IFREG >> S_SHIFT]	= EXT2_FT_REG_FILE,
226 	[S_IFDIR >> S_SHIFT]	= EXT2_FT_DIR,
227 	[S_IFCHR >> S_SHIFT]	= EXT2_FT_CHRDEV,
228 	[S_IFBLK >> S_SHIFT]	= EXT2_FT_BLKDEV,
229 	[S_IFIFO >> S_SHIFT]	= EXT2_FT_FIFO,
230 	[S_IFSOCK >> S_SHIFT]	= EXT2_FT_SOCK,
231 	[S_IFLNK >> S_SHIFT]	= EXT2_FT_SYMLINK,
232 };
233 
234 static inline void ext2_set_de_type(ext2_dirent *de, struct inode *inode)
235 {
236 	mode_t mode = inode->i_mode;
237 	if (EXT2_HAS_INCOMPAT_FEATURE(inode->i_sb, EXT2_FEATURE_INCOMPAT_FILETYPE))
238 		de->file_type = ext2_type_by_mode[(mode & S_IFMT)>>S_SHIFT];
239 	else
240 		de->file_type = 0;
241 }
242 
243 static int
244 ext2_readdir (struct file * filp, void * dirent, filldir_t filldir)
245 {
246 	loff_t pos = filp->f_pos;
247 	struct inode *inode = filp->f_path.dentry->d_inode;
248 	struct super_block *sb = inode->i_sb;
249 	unsigned int offset = pos & ~PAGE_CACHE_MASK;
250 	unsigned long n = pos >> PAGE_CACHE_SHIFT;
251 	unsigned long npages = dir_pages(inode);
252 	unsigned chunk_mask = ~(ext2_chunk_size(inode)-1);
253 	unsigned char *types = NULL;
254 	int need_revalidate = filp->f_version != inode->i_version;
255 
256 	if (pos > inode->i_size - EXT2_DIR_REC_LEN(1))
257 		return 0;
258 
259 	if (EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_FILETYPE))
260 		types = ext2_filetype_table;
261 
262 	for ( ; n < npages; n++, offset = 0) {
263 		char *kaddr, *limit;
264 		ext2_dirent *de;
265 		struct page *page = ext2_get_page(inode, n);
266 
267 		if (IS_ERR(page)) {
268 			ext2_error(sb, __FUNCTION__,
269 				   "bad page in #%lu",
270 				   inode->i_ino);
271 			filp->f_pos += PAGE_CACHE_SIZE - offset;
272 			return -EIO;
273 		}
274 		kaddr = page_address(page);
275 		if (unlikely(need_revalidate)) {
276 			if (offset) {
277 				offset = ext2_validate_entry(kaddr, offset, chunk_mask);
278 				filp->f_pos = (n<<PAGE_CACHE_SHIFT) + offset;
279 			}
280 			filp->f_version = inode->i_version;
281 			need_revalidate = 0;
282 		}
283 		de = (ext2_dirent *)(kaddr+offset);
284 		limit = kaddr + ext2_last_byte(inode, n) - EXT2_DIR_REC_LEN(1);
285 		for ( ;(char*)de <= limit; de = ext2_next_entry(de)) {
286 			if (de->rec_len == 0) {
287 				ext2_error(sb, __FUNCTION__,
288 					"zero-length directory entry");
289 				ext2_put_page(page);
290 				return -EIO;
291 			}
292 			if (de->inode) {
293 				int over;
294 				unsigned char d_type = DT_UNKNOWN;
295 
296 				if (types && de->file_type < EXT2_FT_MAX)
297 					d_type = types[de->file_type];
298 
299 				offset = (char *)de - kaddr;
300 				over = filldir(dirent, de->name, de->name_len,
301 						(n<<PAGE_CACHE_SHIFT) | offset,
302 						le32_to_cpu(de->inode), d_type);
303 				if (over) {
304 					ext2_put_page(page);
305 					return 0;
306 				}
307 			}
308 			filp->f_pos += le16_to_cpu(de->rec_len);
309 		}
310 		ext2_put_page(page);
311 	}
312 	return 0;
313 }
314 
315 /*
316  *	ext2_find_entry()
317  *
318  * finds an entry in the specified directory with the wanted name. It
319  * returns the page in which the entry was found, and the entry itself
320  * (as a parameter - res_dir). Page is returned mapped and unlocked.
321  * Entry is guaranteed to be valid.
322  */
323 struct ext2_dir_entry_2 * ext2_find_entry (struct inode * dir,
324 			struct dentry *dentry, struct page ** res_page)
325 {
326 	const char *name = dentry->d_name.name;
327 	int namelen = dentry->d_name.len;
328 	unsigned reclen = EXT2_DIR_REC_LEN(namelen);
329 	unsigned long start, n;
330 	unsigned long npages = dir_pages(dir);
331 	struct page *page = NULL;
332 	struct ext2_inode_info *ei = EXT2_I(dir);
333 	ext2_dirent * de;
334 
335 	if (npages == 0)
336 		goto out;
337 
338 	/* OFFSET_CACHE */
339 	*res_page = NULL;
340 
341 	start = ei->i_dir_start_lookup;
342 	if (start >= npages)
343 		start = 0;
344 	n = start;
345 	do {
346 		char *kaddr;
347 		page = ext2_get_page(dir, n);
348 		if (!IS_ERR(page)) {
349 			kaddr = page_address(page);
350 			de = (ext2_dirent *) kaddr;
351 			kaddr += ext2_last_byte(dir, n) - reclen;
352 			while ((char *) de <= kaddr) {
353 				if (de->rec_len == 0) {
354 					ext2_error(dir->i_sb, __FUNCTION__,
355 						"zero-length directory entry");
356 					ext2_put_page(page);
357 					goto out;
358 				}
359 				if (ext2_match (namelen, name, de))
360 					goto found;
361 				de = ext2_next_entry(de);
362 			}
363 			ext2_put_page(page);
364 		}
365 		if (++n >= npages)
366 			n = 0;
367 		/* next page is past the blocks we've got */
368 		if (unlikely(n > (dir->i_blocks >> (PAGE_CACHE_SHIFT - 9)))) {
369 			ext2_error(dir->i_sb, __FUNCTION__,
370 				"dir %lu size %lld exceeds block count %llu",
371 				dir->i_ino, dir->i_size,
372 				(unsigned long long)dir->i_blocks);
373 			goto out;
374 		}
375 	} while (n != start);
376 out:
377 	return NULL;
378 
379 found:
380 	*res_page = page;
381 	ei->i_dir_start_lookup = n;
382 	return de;
383 }
384 
385 struct ext2_dir_entry_2 * ext2_dotdot (struct inode *dir, struct page **p)
386 {
387 	struct page *page = ext2_get_page(dir, 0);
388 	ext2_dirent *de = NULL;
389 
390 	if (!IS_ERR(page)) {
391 		de = ext2_next_entry((ext2_dirent *) page_address(page));
392 		*p = page;
393 	}
394 	return de;
395 }
396 
397 ino_t ext2_inode_by_name(struct inode * dir, struct dentry *dentry)
398 {
399 	ino_t res = 0;
400 	struct ext2_dir_entry_2 * de;
401 	struct page *page;
402 
403 	de = ext2_find_entry (dir, dentry, &page);
404 	if (de) {
405 		res = le32_to_cpu(de->inode);
406 		ext2_put_page(page);
407 	}
408 	return res;
409 }
410 
411 /* Releases the page */
412 void ext2_set_link(struct inode *dir, struct ext2_dir_entry_2 *de,
413 			struct page *page, struct inode *inode)
414 {
415 	unsigned from = (char *) de - (char *) page_address(page);
416 	unsigned to = from + le16_to_cpu(de->rec_len);
417 	int err;
418 
419 	lock_page(page);
420 	err = page->mapping->a_ops->prepare_write(NULL, page, from, to);
421 	BUG_ON(err);
422 	de->inode = cpu_to_le32(inode->i_ino);
423 	ext2_set_de_type (de, inode);
424 	err = ext2_commit_chunk(page, from, to);
425 	ext2_put_page(page);
426 	dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
427 	EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL;
428 	mark_inode_dirty(dir);
429 }
430 
431 /*
432  *	Parent is locked.
433  */
434 int ext2_add_link (struct dentry *dentry, struct inode *inode)
435 {
436 	struct inode *dir = dentry->d_parent->d_inode;
437 	const char *name = dentry->d_name.name;
438 	int namelen = dentry->d_name.len;
439 	unsigned chunk_size = ext2_chunk_size(dir);
440 	unsigned reclen = EXT2_DIR_REC_LEN(namelen);
441 	unsigned short rec_len, name_len;
442 	struct page *page = NULL;
443 	ext2_dirent * de;
444 	unsigned long npages = dir_pages(dir);
445 	unsigned long n;
446 	char *kaddr;
447 	unsigned from, to;
448 	int err;
449 
450 	/*
451 	 * We take care of directory expansion in the same loop.
452 	 * This code plays outside i_size, so it locks the page
453 	 * to protect that region.
454 	 */
455 	for (n = 0; n <= npages; n++) {
456 		char *dir_end;
457 
458 		page = ext2_get_page(dir, n);
459 		err = PTR_ERR(page);
460 		if (IS_ERR(page))
461 			goto out;
462 		lock_page(page);
463 		kaddr = page_address(page);
464 		dir_end = kaddr + ext2_last_byte(dir, n);
465 		de = (ext2_dirent *)kaddr;
466 		kaddr += PAGE_CACHE_SIZE - reclen;
467 		while ((char *)de <= kaddr) {
468 			if ((char *)de == dir_end) {
469 				/* We hit i_size */
470 				name_len = 0;
471 				rec_len = chunk_size;
472 				de->rec_len = cpu_to_le16(chunk_size);
473 				de->inode = 0;
474 				goto got_it;
475 			}
476 			if (de->rec_len == 0) {
477 				ext2_error(dir->i_sb, __FUNCTION__,
478 					"zero-length directory entry");
479 				err = -EIO;
480 				goto out_unlock;
481 			}
482 			err = -EEXIST;
483 			if (ext2_match (namelen, name, de))
484 				goto out_unlock;
485 			name_len = EXT2_DIR_REC_LEN(de->name_len);
486 			rec_len = le16_to_cpu(de->rec_len);
487 			if (!de->inode && rec_len >= reclen)
488 				goto got_it;
489 			if (rec_len >= name_len + reclen)
490 				goto got_it;
491 			de = (ext2_dirent *) ((char *) de + rec_len);
492 		}
493 		unlock_page(page);
494 		ext2_put_page(page);
495 	}
496 	BUG();
497 	return -EINVAL;
498 
499 got_it:
500 	from = (char*)de - (char*)page_address(page);
501 	to = from + rec_len;
502 	err = page->mapping->a_ops->prepare_write(NULL, page, from, to);
503 	if (err)
504 		goto out_unlock;
505 	if (de->inode) {
506 		ext2_dirent *de1 = (ext2_dirent *) ((char *) de + name_len);
507 		de1->rec_len = cpu_to_le16(rec_len - name_len);
508 		de->rec_len = cpu_to_le16(name_len);
509 		de = de1;
510 	}
511 	de->name_len = namelen;
512 	memcpy (de->name, name, namelen);
513 	de->inode = cpu_to_le32(inode->i_ino);
514 	ext2_set_de_type (de, inode);
515 	err = ext2_commit_chunk(page, from, to);
516 	dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
517 	EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL;
518 	mark_inode_dirty(dir);
519 	/* OFFSET_CACHE */
520 out_put:
521 	ext2_put_page(page);
522 out:
523 	return err;
524 out_unlock:
525 	unlock_page(page);
526 	goto out_put;
527 }
528 
529 /*
530  * ext2_delete_entry deletes a directory entry by merging it with the
531  * previous entry. Page is up-to-date. Releases the page.
532  */
533 int ext2_delete_entry (struct ext2_dir_entry_2 * dir, struct page * page )
534 {
535 	struct address_space *mapping = page->mapping;
536 	struct inode *inode = mapping->host;
537 	char *kaddr = page_address(page);
538 	unsigned from = ((char*)dir - kaddr) & ~(ext2_chunk_size(inode)-1);
539 	unsigned to = ((char*)dir - kaddr) + le16_to_cpu(dir->rec_len);
540 	ext2_dirent * pde = NULL;
541 	ext2_dirent * de = (ext2_dirent *) (kaddr + from);
542 	int err;
543 
544 	while ((char*)de < (char*)dir) {
545 		if (de->rec_len == 0) {
546 			ext2_error(inode->i_sb, __FUNCTION__,
547 				"zero-length directory entry");
548 			err = -EIO;
549 			goto out;
550 		}
551 		pde = de;
552 		de = ext2_next_entry(de);
553 	}
554 	if (pde)
555 		from = (char*)pde - (char*)page_address(page);
556 	lock_page(page);
557 	err = mapping->a_ops->prepare_write(NULL, page, from, to);
558 	BUG_ON(err);
559 	if (pde)
560 		pde->rec_len = cpu_to_le16(to-from);
561 	dir->inode = 0;
562 	err = ext2_commit_chunk(page, from, to);
563 	inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
564 	EXT2_I(inode)->i_flags &= ~EXT2_BTREE_FL;
565 	mark_inode_dirty(inode);
566 out:
567 	ext2_put_page(page);
568 	return err;
569 }
570 
571 /*
572  * Set the first fragment of directory.
573  */
574 int ext2_make_empty(struct inode *inode, struct inode *parent)
575 {
576 	struct address_space *mapping = inode->i_mapping;
577 	struct page *page = grab_cache_page(mapping, 0);
578 	unsigned chunk_size = ext2_chunk_size(inode);
579 	struct ext2_dir_entry_2 * de;
580 	int err;
581 	void *kaddr;
582 
583 	if (!page)
584 		return -ENOMEM;
585 	err = mapping->a_ops->prepare_write(NULL, page, 0, chunk_size);
586 	if (err) {
587 		unlock_page(page);
588 		goto fail;
589 	}
590 	kaddr = kmap_atomic(page, KM_USER0);
591 	memset(kaddr, 0, chunk_size);
592 	de = (struct ext2_dir_entry_2 *)kaddr;
593 	de->name_len = 1;
594 	de->rec_len = cpu_to_le16(EXT2_DIR_REC_LEN(1));
595 	memcpy (de->name, ".\0\0", 4);
596 	de->inode = cpu_to_le32(inode->i_ino);
597 	ext2_set_de_type (de, inode);
598 
599 	de = (struct ext2_dir_entry_2 *)(kaddr + EXT2_DIR_REC_LEN(1));
600 	de->name_len = 2;
601 	de->rec_len = cpu_to_le16(chunk_size - EXT2_DIR_REC_LEN(1));
602 	de->inode = cpu_to_le32(parent->i_ino);
603 	memcpy (de->name, "..\0", 4);
604 	ext2_set_de_type (de, inode);
605 	kunmap_atomic(kaddr, KM_USER0);
606 	err = ext2_commit_chunk(page, 0, chunk_size);
607 fail:
608 	page_cache_release(page);
609 	return err;
610 }
611 
612 /*
613  * routine to check that the specified directory is empty (for rmdir)
614  */
615 int ext2_empty_dir (struct inode * inode)
616 {
617 	struct page *page = NULL;
618 	unsigned long i, npages = dir_pages(inode);
619 
620 	for (i = 0; i < npages; i++) {
621 		char *kaddr;
622 		ext2_dirent * de;
623 		page = ext2_get_page(inode, i);
624 
625 		if (IS_ERR(page))
626 			continue;
627 
628 		kaddr = page_address(page);
629 		de = (ext2_dirent *)kaddr;
630 		kaddr += ext2_last_byte(inode, i) - EXT2_DIR_REC_LEN(1);
631 
632 		while ((char *)de <= kaddr) {
633 			if (de->rec_len == 0) {
634 				ext2_error(inode->i_sb, __FUNCTION__,
635 					"zero-length directory entry");
636 				printk("kaddr=%p, de=%p\n", kaddr, de);
637 				goto not_empty;
638 			}
639 			if (de->inode != 0) {
640 				/* check for . and .. */
641 				if (de->name[0] != '.')
642 					goto not_empty;
643 				if (de->name_len > 2)
644 					goto not_empty;
645 				if (de->name_len < 2) {
646 					if (de->inode !=
647 					    cpu_to_le32(inode->i_ino))
648 						goto not_empty;
649 				} else if (de->name[1] != '.')
650 					goto not_empty;
651 			}
652 			de = ext2_next_entry(de);
653 		}
654 		ext2_put_page(page);
655 	}
656 	return 1;
657 
658 not_empty:
659 	ext2_put_page(page);
660 	return 0;
661 }
662 
663 const struct file_operations ext2_dir_operations = {
664 	.llseek		= generic_file_llseek,
665 	.read		= generic_read_dir,
666 	.readdir	= ext2_readdir,
667 	.ioctl		= ext2_ioctl,
668 #ifdef CONFIG_COMPAT
669 	.compat_ioctl	= ext2_compat_ioctl,
670 #endif
671 	.fsync		= ext2_sync_file,
672 };
673