xref: /openbmc/linux/fs/ext2/dir.c (revision 82e6fdd6)
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 unsigned char ext2_filetype_table[EXT2_FT_MAX] = {
256 	[EXT2_FT_UNKNOWN]	= DT_UNKNOWN,
257 	[EXT2_FT_REG_FILE]	= DT_REG,
258 	[EXT2_FT_DIR]		= DT_DIR,
259 	[EXT2_FT_CHRDEV]	= DT_CHR,
260 	[EXT2_FT_BLKDEV]	= DT_BLK,
261 	[EXT2_FT_FIFO]		= DT_FIFO,
262 	[EXT2_FT_SOCK]		= DT_SOCK,
263 	[EXT2_FT_SYMLINK]	= DT_LNK,
264 };
265 
266 #define S_SHIFT 12
267 static unsigned char ext2_type_by_mode[S_IFMT >> S_SHIFT] = {
268 	[S_IFREG >> S_SHIFT]	= EXT2_FT_REG_FILE,
269 	[S_IFDIR >> S_SHIFT]	= EXT2_FT_DIR,
270 	[S_IFCHR >> S_SHIFT]	= EXT2_FT_CHRDEV,
271 	[S_IFBLK >> S_SHIFT]	= EXT2_FT_BLKDEV,
272 	[S_IFIFO >> S_SHIFT]	= EXT2_FT_FIFO,
273 	[S_IFSOCK >> S_SHIFT]	= EXT2_FT_SOCK,
274 	[S_IFLNK >> S_SHIFT]	= EXT2_FT_SYMLINK,
275 };
276 
277 static inline void ext2_set_de_type(ext2_dirent *de, struct inode *inode)
278 {
279 	umode_t mode = inode->i_mode;
280 	if (EXT2_HAS_INCOMPAT_FEATURE(inode->i_sb, EXT2_FEATURE_INCOMPAT_FILETYPE))
281 		de->file_type = ext2_type_by_mode[(mode & S_IFMT)>>S_SHIFT];
282 	else
283 		de->file_type = 0;
284 }
285 
286 static int
287 ext2_readdir(struct file *file, struct dir_context *ctx)
288 {
289 	loff_t pos = ctx->pos;
290 	struct inode *inode = file_inode(file);
291 	struct super_block *sb = inode->i_sb;
292 	unsigned int offset = pos & ~PAGE_MASK;
293 	unsigned long n = pos >> PAGE_SHIFT;
294 	unsigned long npages = dir_pages(inode);
295 	unsigned chunk_mask = ~(ext2_chunk_size(inode)-1);
296 	unsigned char *types = NULL;
297 	bool need_revalidate = !inode_eq_iversion(inode, file->f_version);
298 
299 	if (pos > inode->i_size - EXT2_DIR_REC_LEN(1))
300 		return 0;
301 
302 	if (EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_FILETYPE))
303 		types = ext2_filetype_table;
304 
305 	for ( ; n < npages; n++, offset = 0) {
306 		char *kaddr, *limit;
307 		ext2_dirent *de;
308 		struct page *page = ext2_get_page(inode, n, 0);
309 
310 		if (IS_ERR(page)) {
311 			ext2_error(sb, __func__,
312 				   "bad page in #%lu",
313 				   inode->i_ino);
314 			ctx->pos += PAGE_SIZE - offset;
315 			return PTR_ERR(page);
316 		}
317 		kaddr = page_address(page);
318 		if (unlikely(need_revalidate)) {
319 			if (offset) {
320 				offset = ext2_validate_entry(kaddr, offset, chunk_mask);
321 				ctx->pos = (n<<PAGE_SHIFT) + offset;
322 			}
323 			file->f_version = inode_query_iversion(inode);
324 			need_revalidate = false;
325 		}
326 		de = (ext2_dirent *)(kaddr+offset);
327 		limit = kaddr + ext2_last_byte(inode, n) - EXT2_DIR_REC_LEN(1);
328 		for ( ;(char*)de <= limit; de = ext2_next_entry(de)) {
329 			if (de->rec_len == 0) {
330 				ext2_error(sb, __func__,
331 					"zero-length directory entry");
332 				ext2_put_page(page);
333 				return -EIO;
334 			}
335 			if (de->inode) {
336 				unsigned char d_type = DT_UNKNOWN;
337 
338 				if (types && de->file_type < EXT2_FT_MAX)
339 					d_type = types[de->file_type];
340 
341 				if (!dir_emit(ctx, de->name, de->name_len,
342 						le32_to_cpu(de->inode),
343 						d_type)) {
344 					ext2_put_page(page);
345 					return 0;
346 				}
347 			}
348 			ctx->pos += ext2_rec_len_from_disk(de->rec_len);
349 		}
350 		ext2_put_page(page);
351 	}
352 	return 0;
353 }
354 
355 /*
356  *	ext2_find_entry()
357  *
358  * finds an entry in the specified directory with the wanted name. It
359  * returns the page in which the entry was found (as a parameter - res_page),
360  * and the entry itself. Page is returned mapped and unlocked.
361  * Entry is guaranteed to be valid.
362  */
363 struct ext2_dir_entry_2 *ext2_find_entry (struct inode *dir,
364 			const struct qstr *child, struct page **res_page)
365 {
366 	const char *name = child->name;
367 	int namelen = child->len;
368 	unsigned reclen = EXT2_DIR_REC_LEN(namelen);
369 	unsigned long start, n;
370 	unsigned long npages = dir_pages(dir);
371 	struct page *page = NULL;
372 	struct ext2_inode_info *ei = EXT2_I(dir);
373 	ext2_dirent * de;
374 	int dir_has_error = 0;
375 
376 	if (npages == 0)
377 		goto out;
378 
379 	/* OFFSET_CACHE */
380 	*res_page = NULL;
381 
382 	start = ei->i_dir_start_lookup;
383 	if (start >= npages)
384 		start = 0;
385 	n = start;
386 	do {
387 		char *kaddr;
388 		page = ext2_get_page(dir, n, dir_has_error);
389 		if (!IS_ERR(page)) {
390 			kaddr = page_address(page);
391 			de = (ext2_dirent *) kaddr;
392 			kaddr += ext2_last_byte(dir, n) - reclen;
393 			while ((char *) de <= kaddr) {
394 				if (de->rec_len == 0) {
395 					ext2_error(dir->i_sb, __func__,
396 						"zero-length directory entry");
397 					ext2_put_page(page);
398 					goto out;
399 				}
400 				if (ext2_match (namelen, name, de))
401 					goto found;
402 				de = ext2_next_entry(de);
403 			}
404 			ext2_put_page(page);
405 		} else
406 			dir_has_error = 1;
407 
408 		if (++n >= npages)
409 			n = 0;
410 		/* next page is past the blocks we've got */
411 		if (unlikely(n > (dir->i_blocks >> (PAGE_SHIFT - 9)))) {
412 			ext2_error(dir->i_sb, __func__,
413 				"dir %lu size %lld exceeds block count %llu",
414 				dir->i_ino, dir->i_size,
415 				(unsigned long long)dir->i_blocks);
416 			goto out;
417 		}
418 	} while (n != start);
419 out:
420 	return NULL;
421 
422 found:
423 	*res_page = page;
424 	ei->i_dir_start_lookup = n;
425 	return de;
426 }
427 
428 struct ext2_dir_entry_2 * ext2_dotdot (struct inode *dir, struct page **p)
429 {
430 	struct page *page = ext2_get_page(dir, 0, 0);
431 	ext2_dirent *de = NULL;
432 
433 	if (!IS_ERR(page)) {
434 		de = ext2_next_entry((ext2_dirent *) page_address(page));
435 		*p = page;
436 	}
437 	return de;
438 }
439 
440 ino_t ext2_inode_by_name(struct inode *dir, const struct qstr *child)
441 {
442 	ino_t res = 0;
443 	struct ext2_dir_entry_2 *de;
444 	struct page *page;
445 
446 	de = ext2_find_entry (dir, child, &page);
447 	if (de) {
448 		res = le32_to_cpu(de->inode);
449 		ext2_put_page(page);
450 	}
451 	return res;
452 }
453 
454 static int ext2_prepare_chunk(struct page *page, loff_t pos, unsigned len)
455 {
456 	return __block_write_begin(page, pos, len, ext2_get_block);
457 }
458 
459 /* Releases the page */
460 void ext2_set_link(struct inode *dir, struct ext2_dir_entry_2 *de,
461 		   struct page *page, struct inode *inode, int update_times)
462 {
463 	loff_t pos = page_offset(page) +
464 			(char *) de - (char *) page_address(page);
465 	unsigned len = ext2_rec_len_from_disk(de->rec_len);
466 	int err;
467 
468 	lock_page(page);
469 	err = ext2_prepare_chunk(page, pos, len);
470 	BUG_ON(err);
471 	de->inode = cpu_to_le32(inode->i_ino);
472 	ext2_set_de_type(de, inode);
473 	err = ext2_commit_chunk(page, pos, len);
474 	ext2_put_page(page);
475 	if (update_times)
476 		dir->i_mtime = dir->i_ctime = current_time(dir);
477 	EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL;
478 	mark_inode_dirty(dir);
479 }
480 
481 /*
482  *	Parent is locked.
483  */
484 int ext2_add_link (struct dentry *dentry, struct inode *inode)
485 {
486 	struct inode *dir = d_inode(dentry->d_parent);
487 	const char *name = dentry->d_name.name;
488 	int namelen = dentry->d_name.len;
489 	unsigned chunk_size = ext2_chunk_size(dir);
490 	unsigned reclen = EXT2_DIR_REC_LEN(namelen);
491 	unsigned short rec_len, name_len;
492 	struct page *page = NULL;
493 	ext2_dirent * de;
494 	unsigned long npages = dir_pages(dir);
495 	unsigned long n;
496 	char *kaddr;
497 	loff_t pos;
498 	int err;
499 
500 	/*
501 	 * We take care of directory expansion in the same loop.
502 	 * This code plays outside i_size, so it locks the page
503 	 * to protect that region.
504 	 */
505 	for (n = 0; n <= npages; n++) {
506 		char *dir_end;
507 
508 		page = ext2_get_page(dir, n, 0);
509 		err = PTR_ERR(page);
510 		if (IS_ERR(page))
511 			goto out;
512 		lock_page(page);
513 		kaddr = page_address(page);
514 		dir_end = kaddr + ext2_last_byte(dir, n);
515 		de = (ext2_dirent *)kaddr;
516 		kaddr += PAGE_SIZE - reclen;
517 		while ((char *)de <= kaddr) {
518 			if ((char *)de == dir_end) {
519 				/* We hit i_size */
520 				name_len = 0;
521 				rec_len = chunk_size;
522 				de->rec_len = ext2_rec_len_to_disk(chunk_size);
523 				de->inode = 0;
524 				goto got_it;
525 			}
526 			if (de->rec_len == 0) {
527 				ext2_error(dir->i_sb, __func__,
528 					"zero-length directory entry");
529 				err = -EIO;
530 				goto out_unlock;
531 			}
532 			err = -EEXIST;
533 			if (ext2_match (namelen, name, de))
534 				goto out_unlock;
535 			name_len = EXT2_DIR_REC_LEN(de->name_len);
536 			rec_len = ext2_rec_len_from_disk(de->rec_len);
537 			if (!de->inode && rec_len >= reclen)
538 				goto got_it;
539 			if (rec_len >= name_len + reclen)
540 				goto got_it;
541 			de = (ext2_dirent *) ((char *) de + rec_len);
542 		}
543 		unlock_page(page);
544 		ext2_put_page(page);
545 	}
546 	BUG();
547 	return -EINVAL;
548 
549 got_it:
550 	pos = page_offset(page) +
551 		(char*)de - (char*)page_address(page);
552 	err = ext2_prepare_chunk(page, pos, rec_len);
553 	if (err)
554 		goto out_unlock;
555 	if (de->inode) {
556 		ext2_dirent *de1 = (ext2_dirent *) ((char *) de + name_len);
557 		de1->rec_len = ext2_rec_len_to_disk(rec_len - name_len);
558 		de->rec_len = ext2_rec_len_to_disk(name_len);
559 		de = de1;
560 	}
561 	de->name_len = namelen;
562 	memcpy(de->name, name, namelen);
563 	de->inode = cpu_to_le32(inode->i_ino);
564 	ext2_set_de_type (de, inode);
565 	err = ext2_commit_chunk(page, pos, rec_len);
566 	dir->i_mtime = dir->i_ctime = current_time(dir);
567 	EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL;
568 	mark_inode_dirty(dir);
569 	/* OFFSET_CACHE */
570 out_put:
571 	ext2_put_page(page);
572 out:
573 	return err;
574 out_unlock:
575 	unlock_page(page);
576 	goto out_put;
577 }
578 
579 /*
580  * ext2_delete_entry deletes a directory entry by merging it with the
581  * previous entry. Page is up-to-date. Releases the page.
582  */
583 int ext2_delete_entry (struct ext2_dir_entry_2 * dir, struct page * page )
584 {
585 	struct inode *inode = page->mapping->host;
586 	char *kaddr = page_address(page);
587 	unsigned from = ((char*)dir - kaddr) & ~(ext2_chunk_size(inode)-1);
588 	unsigned to = ((char *)dir - kaddr) +
589 				ext2_rec_len_from_disk(dir->rec_len);
590 	loff_t pos;
591 	ext2_dirent * pde = NULL;
592 	ext2_dirent * de = (ext2_dirent *) (kaddr + from);
593 	int err;
594 
595 	while ((char*)de < (char*)dir) {
596 		if (de->rec_len == 0) {
597 			ext2_error(inode->i_sb, __func__,
598 				"zero-length directory entry");
599 			err = -EIO;
600 			goto out;
601 		}
602 		pde = de;
603 		de = ext2_next_entry(de);
604 	}
605 	if (pde)
606 		from = (char*)pde - (char*)page_address(page);
607 	pos = page_offset(page) + from;
608 	lock_page(page);
609 	err = ext2_prepare_chunk(page, pos, to - from);
610 	BUG_ON(err);
611 	if (pde)
612 		pde->rec_len = ext2_rec_len_to_disk(to - from);
613 	dir->inode = 0;
614 	err = ext2_commit_chunk(page, pos, to - from);
615 	inode->i_ctime = inode->i_mtime = current_time(inode);
616 	EXT2_I(inode)->i_flags &= ~EXT2_BTREE_FL;
617 	mark_inode_dirty(inode);
618 out:
619 	ext2_put_page(page);
620 	return err;
621 }
622 
623 /*
624  * Set the first fragment of directory.
625  */
626 int ext2_make_empty(struct inode *inode, struct inode *parent)
627 {
628 	struct page *page = grab_cache_page(inode->i_mapping, 0);
629 	unsigned chunk_size = ext2_chunk_size(inode);
630 	struct ext2_dir_entry_2 * de;
631 	int err;
632 	void *kaddr;
633 
634 	if (!page)
635 		return -ENOMEM;
636 
637 	err = ext2_prepare_chunk(page, 0, chunk_size);
638 	if (err) {
639 		unlock_page(page);
640 		goto fail;
641 	}
642 	kaddr = kmap_atomic(page);
643 	memset(kaddr, 0, chunk_size);
644 	de = (struct ext2_dir_entry_2 *)kaddr;
645 	de->name_len = 1;
646 	de->rec_len = ext2_rec_len_to_disk(EXT2_DIR_REC_LEN(1));
647 	memcpy (de->name, ".\0\0", 4);
648 	de->inode = cpu_to_le32(inode->i_ino);
649 	ext2_set_de_type (de, inode);
650 
651 	de = (struct ext2_dir_entry_2 *)(kaddr + EXT2_DIR_REC_LEN(1));
652 	de->name_len = 2;
653 	de->rec_len = ext2_rec_len_to_disk(chunk_size - EXT2_DIR_REC_LEN(1));
654 	de->inode = cpu_to_le32(parent->i_ino);
655 	memcpy (de->name, "..\0", 4);
656 	ext2_set_de_type (de, inode);
657 	kunmap_atomic(kaddr);
658 	err = ext2_commit_chunk(page, 0, chunk_size);
659 fail:
660 	put_page(page);
661 	return err;
662 }
663 
664 /*
665  * routine to check that the specified directory is empty (for rmdir)
666  */
667 int ext2_empty_dir (struct inode * inode)
668 {
669 	struct page *page = NULL;
670 	unsigned long i, npages = dir_pages(inode);
671 	int dir_has_error = 0;
672 
673 	for (i = 0; i < npages; i++) {
674 		char *kaddr;
675 		ext2_dirent * de;
676 		page = ext2_get_page(inode, i, dir_has_error);
677 
678 		if (IS_ERR(page)) {
679 			dir_has_error = 1;
680 			continue;
681 		}
682 
683 		kaddr = page_address(page);
684 		de = (ext2_dirent *)kaddr;
685 		kaddr += ext2_last_byte(inode, i) - EXT2_DIR_REC_LEN(1);
686 
687 		while ((char *)de <= kaddr) {
688 			if (de->rec_len == 0) {
689 				ext2_error(inode->i_sb, __func__,
690 					"zero-length directory entry");
691 				printk("kaddr=%p, de=%p\n", kaddr, de);
692 				goto not_empty;
693 			}
694 			if (de->inode != 0) {
695 				/* check for . and .. */
696 				if (de->name[0] != '.')
697 					goto not_empty;
698 				if (de->name_len > 2)
699 					goto not_empty;
700 				if (de->name_len < 2) {
701 					if (de->inode !=
702 					    cpu_to_le32(inode->i_ino))
703 						goto not_empty;
704 				} else if (de->name[1] != '.')
705 					goto not_empty;
706 			}
707 			de = ext2_next_entry(de);
708 		}
709 		ext2_put_page(page);
710 	}
711 	return 1;
712 
713 not_empty:
714 	ext2_put_page(page);
715 	return 0;
716 }
717 
718 const struct file_operations ext2_dir_operations = {
719 	.llseek		= generic_file_llseek,
720 	.read		= generic_read_dir,
721 	.iterate_shared	= ext2_readdir,
722 	.unlocked_ioctl = ext2_ioctl,
723 #ifdef CONFIG_COMPAT
724 	.compat_ioctl	= ext2_compat_ioctl,
725 #endif
726 	.fsync		= ext2_fsync,
727 };
728