xref: /openbmc/linux/fs/ext2/dir.c (revision a5b2c10c) 
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *  linux/fs/ext2/dir.c
4  *
5  * Copyright (C) 1992, 1993, 1994, 1995
6  * Remy Card (card@masi.ibp.fr)
7  * Laboratoire MASI - Institut Blaise Pascal
8  * Universite Pierre et Marie Curie (Paris VI)
9  *
10  *  from
11  *
12  *  linux/fs/minix/dir.c
13  *
14  *  Copyright (C) 1991, 1992  Linus Torvalds
15  *
16  *  ext2 directory handling functions
17  *
18  *  Big-endian to little-endian byte-swapping/bitmaps by
19  *        David S. Miller (davem@caip.rutgers.edu), 1995
20  *
21  * All code that works with directory layout had been switched to pagecache
22  * and moved here. AV
23  */
24 
25 #include "ext2.h"
26 #include <linux/buffer_head.h>
27 #include <linux/pagemap.h>
28 #include <linux/swap.h>
29 #include <linux/iversion.h>
30 
31 typedef struct ext2_dir_entry_2 ext2_dirent;
32 
33 /*
34  * Tests against MAX_REC_LEN etc were put in place for 64k block
35  * sizes; if that is not possible on this arch, we can skip
36  * those tests and speed things up.
37  */
38 static inline unsigned ext2_rec_len_from_disk(__le16 dlen)
39 {
40 	unsigned len = le16_to_cpu(dlen);
41 
42 #if (PAGE_SIZE >= 65536)
43 	if (len == EXT2_MAX_REC_LEN)
44 		return 1 << 16;
45 #endif
46 	return len;
47 }
48 
49 static inline __le16 ext2_rec_len_to_disk(unsigned len)
50 {
51 #if (PAGE_SIZE >= 65536)
52 	if (len == (1 << 16))
53 		return cpu_to_le16(EXT2_MAX_REC_LEN);
54 	else
55 		BUG_ON(len > (1 << 16));
56 #endif
57 	return cpu_to_le16(len);
58 }
59 
60 /*
61  * ext2 uses block-sized chunks. Arguably, sector-sized ones would be
62  * more robust, but we have what we have
63  */
64 static inline unsigned ext2_chunk_size(struct inode *inode)
65 {
66 	return inode->i_sb->s_blocksize;
67 }
68 
69 static inline void ext2_put_page(struct page *page)
70 {
71 	kunmap(page);
72 	put_page(page);
73 }
74 
75 /*
76  * Return the offset into page `page_nr' of the last valid
77  * byte in that page, plus one.
78  */
79 static unsigned
80 ext2_last_byte(struct inode *inode, unsigned long page_nr)
81 {
82 	unsigned last_byte = inode->i_size;
83 
84 	last_byte -= page_nr << PAGE_SHIFT;
85 	if (last_byte > PAGE_SIZE)
86 		last_byte = PAGE_SIZE;
87 	return last_byte;
88 }
89 
90 static int ext2_commit_chunk(struct page *page, loff_t pos, unsigned len)
91 {
92 	struct address_space *mapping = page->mapping;
93 	struct inode *dir = mapping->host;
94 	int err = 0;
95 
96 	inode_inc_iversion(dir);
97 	block_write_end(NULL, mapping, pos, len, len, page, NULL);
98 
99 	if (pos+len > dir->i_size) {
100 		i_size_write(dir, pos+len);
101 		mark_inode_dirty(dir);
102 	}
103 
104 	if (IS_DIRSYNC(dir)) {
105 		err = write_one_page(page);
106 		if (!err)
107 			err = sync_inode_metadata(dir, 1);
108 	} else {
109 		unlock_page(page);
110 	}
111 
112 	return err;
113 }
114 
115 static bool ext2_check_page(struct page *page, int quiet)
116 {
117 	struct inode *dir = page->mapping->host;
118 	struct super_block *sb = dir->i_sb;
119 	unsigned chunk_size = ext2_chunk_size(dir);
120 	char *kaddr = page_address(page);
121 	u32 max_inumber = le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count);
122 	unsigned offs, rec_len;
123 	unsigned limit = PAGE_SIZE;
124 	ext2_dirent *p;
125 	char *error;
126 
127 	if ((dir->i_size >> PAGE_SHIFT) == page->index) {
128 		limit = dir->i_size & ~PAGE_MASK;
129 		if (limit & (chunk_size - 1))
130 			goto Ebadsize;
131 		if (!limit)
132 			goto out;
133 	}
134 	for (offs = 0; offs <= limit - EXT2_DIR_REC_LEN(1); offs += rec_len) {
135 		p = (ext2_dirent *)(kaddr + offs);
136 		rec_len = ext2_rec_len_from_disk(p->rec_len);
137 
138 		if (unlikely(rec_len < EXT2_DIR_REC_LEN(1)))
139 			goto Eshort;
140 		if (unlikely(rec_len & 3))
141 			goto Ealign;
142 		if (unlikely(rec_len < EXT2_DIR_REC_LEN(p->name_len)))
143 			goto Enamelen;
144 		if (unlikely(((offs + rec_len - 1) ^ offs) & ~(chunk_size-1)))
145 			goto Espan;
146 		if (unlikely(le32_to_cpu(p->inode) > max_inumber))
147 			goto Einumber;
148 	}
149 	if (offs != limit)
150 		goto Eend;
151 out:
152 	SetPageChecked(page);
153 	return true;
154 
155 	/* Too bad, we had an error */
156 
157 Ebadsize:
158 	if (!quiet)
159 		ext2_error(sb, __func__,
160 			"size of directory #%lu is not a multiple "
161 			"of chunk size", dir->i_ino);
162 	goto fail;
163 Eshort:
164 	error = "rec_len is smaller than minimal";
165 	goto bad_entry;
166 Ealign:
167 	error = "unaligned directory entry";
168 	goto bad_entry;
169 Enamelen:
170 	error = "rec_len is too small for name_len";
171 	goto bad_entry;
172 Espan:
173 	error = "directory entry across blocks";
174 	goto bad_entry;
175 Einumber:
176 	error = "inode out of bounds";
177 bad_entry:
178 	if (!quiet)
179 		ext2_error(sb, __func__, "bad entry in directory #%lu: : %s - "
180 			"offset=%lu, inode=%lu, rec_len=%d, name_len=%d",
181 			dir->i_ino, error, (page->index<<PAGE_SHIFT)+offs,
182 			(unsigned long) le32_to_cpu(p->inode),
183 			rec_len, p->name_len);
184 	goto fail;
185 Eend:
186 	if (!quiet) {
187 		p = (ext2_dirent *)(kaddr + offs);
188 		ext2_error(sb, "ext2_check_page",
189 			"entry in directory #%lu spans the page boundary"
190 			"offset=%lu, inode=%lu",
191 			dir->i_ino, (page->index<<PAGE_SHIFT)+offs,
192 			(unsigned long) le32_to_cpu(p->inode));
193 	}
194 fail:
195 	SetPageError(page);
196 	return false;
197 }
198 
199 static struct page * ext2_get_page(struct inode *dir, unsigned long n,
200 				   int quiet)
201 {
202 	struct address_space *mapping = dir->i_mapping;
203 	struct page *page = read_mapping_page(mapping, n, NULL);
204 	if (!IS_ERR(page)) {
205 		kmap(page);
206 		if (unlikely(!PageChecked(page))) {
207 			if (PageError(page) || !ext2_check_page(page, quiet))
208 				goto fail;
209 		}
210 	}
211 	return page;
212 
213 fail:
214 	ext2_put_page(page);
215 	return ERR_PTR(-EIO);
216 }
217 
218 /*
219  * NOTE! unlike strncmp, ext2_match returns 1 for success, 0 for failure.
220  *
221  * len <= EXT2_NAME_LEN and de != NULL are guaranteed by caller.
222  */
223 static inline int ext2_match (int len, const char * const name,
224 					struct ext2_dir_entry_2 * de)
225 {
226 	if (len != de->name_len)
227 		return 0;
228 	if (!de->inode)
229 		return 0;
230 	return !memcmp(name, de->name, len);
231 }
232 
233 /*
234  * p is at least 6 bytes before the end of page
235  */
236 static inline ext2_dirent *ext2_next_entry(ext2_dirent *p)
237 {
238 	return (ext2_dirent *)((char *)p +
239 			ext2_rec_len_from_disk(p->rec_len));
240 }
241 
242 static inline unsigned
243 ext2_validate_entry(char *base, unsigned offset, unsigned mask)
244 {
245 	ext2_dirent *de = (ext2_dirent*)(base + offset);
246 	ext2_dirent *p = (ext2_dirent*)(base + (offset&mask));
247 	while ((char*)p < (char*)de) {
248 		if (p->rec_len == 0)
249 			break;
250 		p = ext2_next_entry(p);
251 	}
252 	return (char *)p - base;
253 }
254 
255 static inline void ext2_set_de_type(ext2_dirent *de, struct inode *inode)
256 {
257 	if (EXT2_HAS_INCOMPAT_FEATURE(inode->i_sb, EXT2_FEATURE_INCOMPAT_FILETYPE))
258 		de->file_type = fs_umode_to_ftype(inode->i_mode);
259 	else
260 		de->file_type = 0;
261 }
262 
263 static int
264 ext2_readdir(struct file *file, struct dir_context *ctx)
265 {
266 	loff_t pos = ctx->pos;
267 	struct inode *inode = file_inode(file);
268 	struct super_block *sb = inode->i_sb;
269 	unsigned int offset = pos & ~PAGE_MASK;
270 	unsigned long n = pos >> PAGE_SHIFT;
271 	unsigned long npages = dir_pages(inode);
272 	unsigned chunk_mask = ~(ext2_chunk_size(inode)-1);
273 	bool need_revalidate = !inode_eq_iversion(inode, file->f_version);
274 	bool has_filetype;
275 
276 	if (pos > inode->i_size - EXT2_DIR_REC_LEN(1))
277 		return 0;
278 
279 	has_filetype =
280 		EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_FILETYPE);
281 
282 	for ( ; n < npages; n++, offset = 0) {
283 		char *kaddr, *limit;
284 		ext2_dirent *de;
285 		struct page *page = ext2_get_page(inode, n, 0);
286 
287 		if (IS_ERR(page)) {
288 			ext2_error(sb, __func__,
289 				   "bad page in #%lu",
290 				   inode->i_ino);
291 			ctx->pos += PAGE_SIZE - offset;
292 			return PTR_ERR(page);
293 		}
294 		kaddr = page_address(page);
295 		if (unlikely(need_revalidate)) {
296 			if (offset) {
297 				offset = ext2_validate_entry(kaddr, offset, chunk_mask);
298 				ctx->pos = (n<<PAGE_SHIFT) + offset;
299 			}
300 			file->f_version = inode_query_iversion(inode);
301 			need_revalidate = false;
302 		}
303 		de = (ext2_dirent *)(kaddr+offset);
304 		limit = kaddr + ext2_last_byte(inode, n) - EXT2_DIR_REC_LEN(1);
305 		for ( ;(char*)de <= limit; de = ext2_next_entry(de)) {
306 			if (de->rec_len == 0) {
307 				ext2_error(sb, __func__,
308 					"zero-length directory entry");
309 				ext2_put_page(page);
310 				return -EIO;
311 			}
312 			if (de->inode) {
313 				unsigned char d_type = DT_UNKNOWN;
314 
315 				if (has_filetype)
316 					d_type = fs_ftype_to_dtype(de->file_type);
317 
318 				if (!dir_emit(ctx, de->name, de->name_len,
319 						le32_to_cpu(de->inode),
320 						d_type)) {
321 					ext2_put_page(page);
322 					return 0;
323 				}
324 			}
325 			ctx->pos += ext2_rec_len_from_disk(de->rec_len);
326 		}
327 		ext2_put_page(page);
328 	}
329 	return 0;
330 }
331 
332 /*
333  *	ext2_find_entry()
334  *
335  * finds an entry in the specified directory with the wanted name. It
336  * returns the page in which the entry was found (as a parameter - res_page),
337  * and the entry itself. Page is returned mapped and unlocked.
338  * Entry is guaranteed to be valid.
339  */
340 struct ext2_dir_entry_2 *ext2_find_entry (struct inode *dir,
341 			const struct qstr *child, struct page **res_page)
342 {
343 	const char *name = child->name;
344 	int namelen = child->len;
345 	unsigned reclen = EXT2_DIR_REC_LEN(namelen);
346 	unsigned long start, n;
347 	unsigned long npages = dir_pages(dir);
348 	struct page *page = NULL;
349 	struct ext2_inode_info *ei = EXT2_I(dir);
350 	ext2_dirent * de;
351 
352 	if (npages == 0)
353 		goto out;
354 
355 	/* OFFSET_CACHE */
356 	*res_page = NULL;
357 
358 	start = ei->i_dir_start_lookup;
359 	if (start >= npages)
360 		start = 0;
361 	n = start;
362 	do {
363 		char *kaddr;
364 		page = ext2_get_page(dir, n, 0);
365 		if (IS_ERR(page))
366 			return ERR_CAST(page);
367 
368 		kaddr = page_address(page);
369 		de = (ext2_dirent *) kaddr;
370 		kaddr += ext2_last_byte(dir, n) - reclen;
371 		while ((char *) de <= kaddr) {
372 			if (de->rec_len == 0) {
373 				ext2_error(dir->i_sb, __func__,
374 					"zero-length directory entry");
375 				ext2_put_page(page);
376 				goto out;
377 			}
378 			if (ext2_match(namelen, name, de))
379 				goto found;
380 			de = ext2_next_entry(de);
381 		}
382 		ext2_put_page(page);
383 
384 		if (++n >= npages)
385 			n = 0;
386 		/* next page is past the blocks we've got */
387 		if (unlikely(n > (dir->i_blocks >> (PAGE_SHIFT - 9)))) {
388 			ext2_error(dir->i_sb, __func__,
389 				"dir %lu size %lld exceeds block count %llu",
390 				dir->i_ino, dir->i_size,
391 				(unsigned long long)dir->i_blocks);
392 			goto out;
393 		}
394 	} while (n != start);
395 out:
396 	return ERR_PTR(-ENOENT);
397 
398 found:
399 	*res_page = page;
400 	ei->i_dir_start_lookup = n;
401 	return de;
402 }
403 
404 struct ext2_dir_entry_2 * ext2_dotdot (struct inode *dir, struct page **p)
405 {
406 	struct page *page = ext2_get_page(dir, 0, 0);
407 	ext2_dirent *de = NULL;
408 
409 	if (!IS_ERR(page)) {
410 		de = ext2_next_entry((ext2_dirent *) page_address(page));
411 		*p = page;
412 	}
413 	return de;
414 }
415 
416 int ext2_inode_by_name(struct inode *dir, const struct qstr *child, ino_t *ino)
417 {
418 	struct ext2_dir_entry_2 *de;
419 	struct page *page;
420 
421 	de = ext2_find_entry(dir, child, &page);
422 	if (IS_ERR(de))
423 		return PTR_ERR(de);
424 
425 	*ino = le32_to_cpu(de->inode);
426 	ext2_put_page(page);
427 	return 0;
428 }
429 
430 static int ext2_prepare_chunk(struct page *page, loff_t pos, unsigned len)
431 {
432 	return __block_write_begin(page, pos, len, ext2_get_block);
433 }
434 
435 /* Releases the page */
436 void ext2_set_link(struct inode *dir, struct ext2_dir_entry_2 *de,
437 		   struct page *page, struct inode *inode, int update_times)
438 {
439 	loff_t pos = page_offset(page) +
440 			(char *) de - (char *) page_address(page);
441 	unsigned len = ext2_rec_len_from_disk(de->rec_len);
442 	int err;
443 
444 	lock_page(page);
445 	err = ext2_prepare_chunk(page, pos, len);
446 	BUG_ON(err);
447 	de->inode = cpu_to_le32(inode->i_ino);
448 	ext2_set_de_type(de, inode);
449 	err = ext2_commit_chunk(page, pos, len);
450 	ext2_put_page(page);
451 	if (update_times)
452 		dir->i_mtime = dir->i_ctime = current_time(dir);
453 	EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL;
454 	mark_inode_dirty(dir);
455 }
456 
457 /*
458  *	Parent is locked.
459  */
460 int ext2_add_link (struct dentry *dentry, struct inode *inode)
461 {
462 	struct inode *dir = d_inode(dentry->d_parent);
463 	const char *name = dentry->d_name.name;
464 	int namelen = dentry->d_name.len;
465 	unsigned chunk_size = ext2_chunk_size(dir);
466 	unsigned reclen = EXT2_DIR_REC_LEN(namelen);
467 	unsigned short rec_len, name_len;
468 	struct page *page = NULL;
469 	ext2_dirent * de;
470 	unsigned long npages = dir_pages(dir);
471 	unsigned long n;
472 	char *kaddr;
473 	loff_t pos;
474 	int err;
475 
476 	/*
477 	 * We take care of directory expansion in the same loop.
478 	 * This code plays outside i_size, so it locks the page
479 	 * to protect that region.
480 	 */
481 	for (n = 0; n <= npages; n++) {
482 		char *dir_end;
483 
484 		page = ext2_get_page(dir, n, 0);
485 		err = PTR_ERR(page);
486 		if (IS_ERR(page))
487 			goto out;
488 		lock_page(page);
489 		kaddr = page_address(page);
490 		dir_end = kaddr + ext2_last_byte(dir, n);
491 		de = (ext2_dirent *)kaddr;
492 		kaddr += PAGE_SIZE - reclen;
493 		while ((char *)de <= kaddr) {
494 			if ((char *)de == dir_end) {
495 				/* We hit i_size */
496 				name_len = 0;
497 				rec_len = chunk_size;
498 				de->rec_len = ext2_rec_len_to_disk(chunk_size);
499 				de->inode = 0;
500 				goto got_it;
501 			}
502 			if (de->rec_len == 0) {
503 				ext2_error(dir->i_sb, __func__,
504 					"zero-length directory entry");
505 				err = -EIO;
506 				goto out_unlock;
507 			}
508 			err = -EEXIST;
509 			if (ext2_match (namelen, name, de))
510 				goto out_unlock;
511 			name_len = EXT2_DIR_REC_LEN(de->name_len);
512 			rec_len = ext2_rec_len_from_disk(de->rec_len);
513 			if (!de->inode && rec_len >= reclen)
514 				goto got_it;
515 			if (rec_len >= name_len + reclen)
516 				goto got_it;
517 			de = (ext2_dirent *) ((char *) de + rec_len);
518 		}
519 		unlock_page(page);
520 		ext2_put_page(page);
521 	}
522 	BUG();
523 	return -EINVAL;
524 
525 got_it:
526 	pos = page_offset(page) +
527 		(char*)de - (char*)page_address(page);
528 	err = ext2_prepare_chunk(page, pos, rec_len);
529 	if (err)
530 		goto out_unlock;
531 	if (de->inode) {
532 		ext2_dirent *de1 = (ext2_dirent *) ((char *) de + name_len);
533 		de1->rec_len = ext2_rec_len_to_disk(rec_len - name_len);
534 		de->rec_len = ext2_rec_len_to_disk(name_len);
535 		de = de1;
536 	}
537 	de->name_len = namelen;
538 	memcpy(de->name, name, namelen);
539 	de->inode = cpu_to_le32(inode->i_ino);
540 	ext2_set_de_type (de, inode);
541 	err = ext2_commit_chunk(page, pos, rec_len);
542 	dir->i_mtime = dir->i_ctime = current_time(dir);
543 	EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL;
544 	mark_inode_dirty(dir);
545 	/* OFFSET_CACHE */
546 out_put:
547 	ext2_put_page(page);
548 out:
549 	return err;
550 out_unlock:
551 	unlock_page(page);
552 	goto out_put;
553 }
554 
555 /*
556  * ext2_delete_entry deletes a directory entry by merging it with the
557  * previous entry. Page is up-to-date. Releases the page.
558  */
559 int ext2_delete_entry (struct ext2_dir_entry_2 * dir, struct page * page )
560 {
561 	struct inode *inode = page->mapping->host;
562 	char *kaddr = page_address(page);
563 	unsigned from = ((char*)dir - kaddr) & ~(ext2_chunk_size(inode)-1);
564 	unsigned to = ((char *)dir - kaddr) +
565 				ext2_rec_len_from_disk(dir->rec_len);
566 	loff_t pos;
567 	ext2_dirent * pde = NULL;
568 	ext2_dirent * de = (ext2_dirent *) (kaddr + from);
569 	int err;
570 
571 	while ((char*)de < (char*)dir) {
572 		if (de->rec_len == 0) {
573 			ext2_error(inode->i_sb, __func__,
574 				"zero-length directory entry");
575 			err = -EIO;
576 			goto out;
577 		}
578 		pde = de;
579 		de = ext2_next_entry(de);
580 	}
581 	if (pde)
582 		from = (char*)pde - (char*)page_address(page);
583 	pos = page_offset(page) + from;
584 	lock_page(page);
585 	err = ext2_prepare_chunk(page, pos, to - from);
586 	BUG_ON(err);
587 	if (pde)
588 		pde->rec_len = ext2_rec_len_to_disk(to - from);
589 	dir->inode = 0;
590 	err = ext2_commit_chunk(page, pos, to - from);
591 	inode->i_ctime = inode->i_mtime = current_time(inode);
592 	EXT2_I(inode)->i_flags &= ~EXT2_BTREE_FL;
593 	mark_inode_dirty(inode);
594 out:
595 	ext2_put_page(page);
596 	return err;
597 }
598 
599 /*
600  * Set the first fragment of directory.
601  */
602 int ext2_make_empty(struct inode *inode, struct inode *parent)
603 {
604 	struct page *page = grab_cache_page(inode->i_mapping, 0);
605 	unsigned chunk_size = ext2_chunk_size(inode);
606 	struct ext2_dir_entry_2 * de;
607 	int err;
608 	void *kaddr;
609 
610 	if (!page)
611 		return -ENOMEM;
612 
613 	err = ext2_prepare_chunk(page, 0, chunk_size);
614 	if (err) {
615 		unlock_page(page);
616 		goto fail;
617 	}
618 	kaddr = kmap_atomic(page);
619 	memset(kaddr, 0, chunk_size);
620 	de = (struct ext2_dir_entry_2 *)kaddr;
621 	de->name_len = 1;
622 	de->rec_len = ext2_rec_len_to_disk(EXT2_DIR_REC_LEN(1));
623 	memcpy (de->name, ".\0\0", 4);
624 	de->inode = cpu_to_le32(inode->i_ino);
625 	ext2_set_de_type (de, inode);
626 
627 	de = (struct ext2_dir_entry_2 *)(kaddr + EXT2_DIR_REC_LEN(1));
628 	de->name_len = 2;
629 	de->rec_len = ext2_rec_len_to_disk(chunk_size - EXT2_DIR_REC_LEN(1));
630 	de->inode = cpu_to_le32(parent->i_ino);
631 	memcpy (de->name, "..\0", 4);
632 	ext2_set_de_type (de, inode);
633 	kunmap_atomic(kaddr);
634 	err = ext2_commit_chunk(page, 0, chunk_size);
635 fail:
636 	put_page(page);
637 	return err;
638 }
639 
640 /*
641  * routine to check that the specified directory is empty (for rmdir)
642  */
643 int ext2_empty_dir (struct inode * inode)
644 {
645 	struct page *page = NULL;
646 	unsigned long i, npages = dir_pages(inode);
647 	int dir_has_error = 0;
648 
649 	for (i = 0; i < npages; i++) {
650 		char *kaddr;
651 		ext2_dirent * de;
652 		page = ext2_get_page(inode, i, dir_has_error);
653 
654 		if (IS_ERR(page)) {
655 			dir_has_error = 1;
656 			continue;
657 		}
658 
659 		kaddr = page_address(page);
660 		de = (ext2_dirent *)kaddr;
661 		kaddr += ext2_last_byte(inode, i) - EXT2_DIR_REC_LEN(1);
662 
663 		while ((char *)de <= kaddr) {
664 			if (de->rec_len == 0) {
665 				ext2_error(inode->i_sb, __func__,
666 					"zero-length directory entry");
667 				printk("kaddr=%p, de=%p\n", kaddr, de);
668 				goto not_empty;
669 			}
670 			if (de->inode != 0) {
671 				/* check for . and .. */
672 				if (de->name[0] != '.')
673 					goto not_empty;
674 				if (de->name_len > 2)
675 					goto not_empty;
676 				if (de->name_len < 2) {
677 					if (de->inode !=
678 					    cpu_to_le32(inode->i_ino))
679 						goto not_empty;
680 				} else if (de->name[1] != '.')
681 					goto not_empty;
682 			}
683 			de = ext2_next_entry(de);
684 		}
685 		ext2_put_page(page);
686 	}
687 	return 1;
688 
689 not_empty:
690 	ext2_put_page(page);
691 	return 0;
692 }
693 
694 const struct file_operations ext2_dir_operations = {
695 	.llseek		= generic_file_llseek,
696 	.read		= generic_read_dir,
697 	.iterate_shared	= ext2_readdir,
698 	.unlocked_ioctl = ext2_ioctl,
699 #ifdef CONFIG_COMPAT
700 	.compat_ioctl	= ext2_compat_ioctl,
701 #endif
702 	.fsync		= ext2_fsync,
703 };
704