xref: /linux/fs/nilfs2/dir.c (revision f884ab15afdc5514e88105c92a4e2e1e6539869a)
1 /*
2  * dir.c - NILFS directory entry operations
3  *
4  * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License as published by
8  * the Free Software Foundation; either version 2 of the License, or
9  * (at your option) any later version.
10  *
11  * This program is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  * GNU General Public License for more details.
15  *
16  * You should have received a copy of the GNU General Public License
17  * along with this program; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
19  *
20  * Modified for NILFS by Amagai Yoshiji <amagai@osrg.net>
21  */
22 /*
23  *  linux/fs/ext2/dir.c
24  *
25  * Copyright (C) 1992, 1993, 1994, 1995
26  * Remy Card (card@masi.ibp.fr)
27  * Laboratoire MASI - Institut Blaise Pascal
28  * Universite Pierre et Marie Curie (Paris VI)
29  *
30  *  from
31  *
32  *  linux/fs/minix/dir.c
33  *
34  *  Copyright (C) 1991, 1992  Linus Torvalds
35  *
36  *  ext2 directory handling functions
37  *
38  *  Big-endian to little-endian byte-swapping/bitmaps by
39  *        David S. Miller (davem@caip.rutgers.edu), 1995
40  *
41  * All code that works with directory layout had been switched to pagecache
42  * and moved here. AV
43  */
44 
45 #include <linux/pagemap.h>
46 #include "nilfs.h"
47 #include "page.h"
48 
49 /*
50  * nilfs uses block-sized chunks. Arguably, sector-sized ones would be
51  * more robust, but we have what we have
52  */
53 static inline unsigned nilfs_chunk_size(struct inode *inode)
54 {
55 	return inode->i_sb->s_blocksize;
56 }
57 
58 static inline void nilfs_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 nilfs_last_byte(struct inode *inode, unsigned long page_nr)
74 {
75 	unsigned last_byte = inode->i_size;
76 
77 	last_byte -= page_nr << PAGE_CACHE_SHIFT;
78 	if (last_byte > PAGE_CACHE_SIZE)
79 		last_byte = PAGE_CACHE_SIZE;
80 	return last_byte;
81 }
82 
83 static int nilfs_prepare_chunk(struct page *page, unsigned from, unsigned to)
84 {
85 	loff_t pos = page_offset(page) + from;
86 	return __block_write_begin(page, pos, to - from, nilfs_get_block);
87 }
88 
89 static void nilfs_commit_chunk(struct page *page,
90 			       struct address_space *mapping,
91 			       unsigned from, unsigned to)
92 {
93 	struct inode *dir = mapping->host;
94 	loff_t pos = page_offset(page) + from;
95 	unsigned len = to - from;
96 	unsigned nr_dirty, copied;
97 	int err;
98 
99 	nr_dirty = nilfs_page_count_clean_buffers(page, from, to);
100 	copied = block_write_end(NULL, mapping, pos, len, len, page, NULL);
101 	if (pos + copied > dir->i_size)
102 		i_size_write(dir, pos + copied);
103 	if (IS_DIRSYNC(dir))
104 		nilfs_set_transaction_flag(NILFS_TI_SYNC);
105 	err = nilfs_set_file_dirty(dir, nr_dirty);
106 	WARN_ON(err); /* do not happen */
107 	unlock_page(page);
108 }
109 
110 static void nilfs_check_page(struct page *page)
111 {
112 	struct inode *dir = page->mapping->host;
113 	struct super_block *sb = dir->i_sb;
114 	unsigned chunk_size = nilfs_chunk_size(dir);
115 	char *kaddr = page_address(page);
116 	unsigned offs, rec_len;
117 	unsigned limit = PAGE_CACHE_SIZE;
118 	struct nilfs_dir_entry *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 - NILFS_DIR_REC_LEN(1); offs += rec_len) {
129 		p = (struct nilfs_dir_entry *)(kaddr + offs);
130 		rec_len = nilfs_rec_len_from_disk(p->rec_len);
131 
132 		if (rec_len < NILFS_DIR_REC_LEN(1))
133 			goto Eshort;
134 		if (rec_len & 3)
135 			goto Ealign;
136 		if (rec_len < NILFS_DIR_REC_LEN(p->name_len))
137 			goto Enamelen;
138 		if (((offs + rec_len - 1) ^ offs) & ~(chunk_size-1))
139 			goto Espan;
140 	}
141 	if (offs != limit)
142 		goto Eend;
143 out:
144 	SetPageChecked(page);
145 	return;
146 
147 	/* Too bad, we had an error */
148 
149 Ebadsize:
150 	nilfs_error(sb, "nilfs_check_page",
151 		    "size of directory #%lu is not a multiple of chunk size",
152 		    dir->i_ino
153 	);
154 	goto fail;
155 Eshort:
156 	error = "rec_len is smaller than minimal";
157 	goto bad_entry;
158 Ealign:
159 	error = "unaligned directory entry";
160 	goto bad_entry;
161 Enamelen:
162 	error = "rec_len is too small for name_len";
163 	goto bad_entry;
164 Espan:
165 	error = "directory entry across blocks";
166 bad_entry:
167 	nilfs_error(sb, "nilfs_check_page", "bad entry in directory #%lu: %s - "
168 		    "offset=%lu, inode=%lu, rec_len=%d, name_len=%d",
169 		    dir->i_ino, error, (page->index<<PAGE_CACHE_SHIFT)+offs,
170 		    (unsigned long) le64_to_cpu(p->inode),
171 		    rec_len, p->name_len);
172 	goto fail;
173 Eend:
174 	p = (struct nilfs_dir_entry *)(kaddr + offs);
175 	nilfs_error(sb, "nilfs_check_page",
176 		    "entry in directory #%lu spans the page boundary"
177 		    "offset=%lu, inode=%lu",
178 		    dir->i_ino, (page->index<<PAGE_CACHE_SHIFT)+offs,
179 		    (unsigned long) le64_to_cpu(p->inode));
180 fail:
181 	SetPageChecked(page);
182 	SetPageError(page);
183 }
184 
185 static struct page *nilfs_get_page(struct inode *dir, unsigned long n)
186 {
187 	struct address_space *mapping = dir->i_mapping;
188 	struct page *page = read_mapping_page(mapping, n, NULL);
189 
190 	if (!IS_ERR(page)) {
191 		kmap(page);
192 		if (!PageChecked(page))
193 			nilfs_check_page(page);
194 		if (PageError(page))
195 			goto fail;
196 	}
197 	return page;
198 
199 fail:
200 	nilfs_put_page(page);
201 	return ERR_PTR(-EIO);
202 }
203 
204 /*
205  * NOTE! unlike strncmp, nilfs_match returns 1 for success, 0 for failure.
206  *
207  * len <= NILFS_NAME_LEN and de != NULL are guaranteed by caller.
208  */
209 static int
210 nilfs_match(int len, const unsigned char *name, struct nilfs_dir_entry *de)
211 {
212 	if (len != de->name_len)
213 		return 0;
214 	if (!de->inode)
215 		return 0;
216 	return !memcmp(name, de->name, len);
217 }
218 
219 /*
220  * p is at least 6 bytes before the end of page
221  */
222 static struct nilfs_dir_entry *nilfs_next_entry(struct nilfs_dir_entry *p)
223 {
224 	return (struct nilfs_dir_entry *)((char *)p +
225 					  nilfs_rec_len_from_disk(p->rec_len));
226 }
227 
228 static unsigned char
229 nilfs_filetype_table[NILFS_FT_MAX] = {
230 	[NILFS_FT_UNKNOWN]	= DT_UNKNOWN,
231 	[NILFS_FT_REG_FILE]	= DT_REG,
232 	[NILFS_FT_DIR]		= DT_DIR,
233 	[NILFS_FT_CHRDEV]	= DT_CHR,
234 	[NILFS_FT_BLKDEV]	= DT_BLK,
235 	[NILFS_FT_FIFO]		= DT_FIFO,
236 	[NILFS_FT_SOCK]		= DT_SOCK,
237 	[NILFS_FT_SYMLINK]	= DT_LNK,
238 };
239 
240 #define S_SHIFT 12
241 static unsigned char
242 nilfs_type_by_mode[S_IFMT >> S_SHIFT] = {
243 	[S_IFREG >> S_SHIFT]	= NILFS_FT_REG_FILE,
244 	[S_IFDIR >> S_SHIFT]	= NILFS_FT_DIR,
245 	[S_IFCHR >> S_SHIFT]	= NILFS_FT_CHRDEV,
246 	[S_IFBLK >> S_SHIFT]	= NILFS_FT_BLKDEV,
247 	[S_IFIFO >> S_SHIFT]	= NILFS_FT_FIFO,
248 	[S_IFSOCK >> S_SHIFT]	= NILFS_FT_SOCK,
249 	[S_IFLNK >> S_SHIFT]	= NILFS_FT_SYMLINK,
250 };
251 
252 static void nilfs_set_de_type(struct nilfs_dir_entry *de, struct inode *inode)
253 {
254 	umode_t mode = inode->i_mode;
255 
256 	de->file_type = nilfs_type_by_mode[(mode & S_IFMT)>>S_SHIFT];
257 }
258 
259 static int nilfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
260 {
261 	loff_t pos = filp->f_pos;
262 	struct inode *inode = file_inode(filp);
263 	struct super_block *sb = inode->i_sb;
264 	unsigned int offset = pos & ~PAGE_CACHE_MASK;
265 	unsigned long n = pos >> PAGE_CACHE_SHIFT;
266 	unsigned long npages = dir_pages(inode);
267 /*	unsigned chunk_mask = ~(nilfs_chunk_size(inode)-1); */
268 	unsigned char *types = NULL;
269 	int ret;
270 
271 	if (pos > inode->i_size - NILFS_DIR_REC_LEN(1))
272 		goto success;
273 
274 	types = nilfs_filetype_table;
275 
276 	for ( ; n < npages; n++, offset = 0) {
277 		char *kaddr, *limit;
278 		struct nilfs_dir_entry *de;
279 		struct page *page = nilfs_get_page(inode, n);
280 
281 		if (IS_ERR(page)) {
282 			nilfs_error(sb, __func__, "bad page in #%lu",
283 				    inode->i_ino);
284 			filp->f_pos += PAGE_CACHE_SIZE - offset;
285 			ret = -EIO;
286 			goto done;
287 		}
288 		kaddr = page_address(page);
289 		de = (struct nilfs_dir_entry *)(kaddr + offset);
290 		limit = kaddr + nilfs_last_byte(inode, n) -
291 			NILFS_DIR_REC_LEN(1);
292 		for ( ; (char *)de <= limit; de = nilfs_next_entry(de)) {
293 			if (de->rec_len == 0) {
294 				nilfs_error(sb, __func__,
295 					    "zero-length directory entry");
296 				ret = -EIO;
297 				nilfs_put_page(page);
298 				goto done;
299 			}
300 			if (de->inode) {
301 				int over;
302 				unsigned char d_type = DT_UNKNOWN;
303 
304 				if (types && de->file_type < NILFS_FT_MAX)
305 					d_type = types[de->file_type];
306 
307 				offset = (char *)de - kaddr;
308 				over = filldir(dirent, de->name, de->name_len,
309 						(n<<PAGE_CACHE_SHIFT) | offset,
310 						le64_to_cpu(de->inode), d_type);
311 				if (over) {
312 					nilfs_put_page(page);
313 					goto success;
314 				}
315 			}
316 			filp->f_pos += nilfs_rec_len_from_disk(de->rec_len);
317 		}
318 		nilfs_put_page(page);
319 	}
320 
321 success:
322 	ret = 0;
323 done:
324 	return ret;
325 }
326 
327 /*
328  *	nilfs_find_entry()
329  *
330  * finds an entry in the specified directory with the wanted name. It
331  * returns the page in which the entry was found, and the entry itself
332  * (as a parameter - res_dir). Page is returned mapped and unlocked.
333  * Entry is guaranteed to be valid.
334  */
335 struct nilfs_dir_entry *
336 nilfs_find_entry(struct inode *dir, const struct qstr *qstr,
337 		 struct page **res_page)
338 {
339 	const unsigned char *name = qstr->name;
340 	int namelen = qstr->len;
341 	unsigned reclen = NILFS_DIR_REC_LEN(namelen);
342 	unsigned long start, n;
343 	unsigned long npages = dir_pages(dir);
344 	struct page *page = NULL;
345 	struct nilfs_inode_info *ei = NILFS_I(dir);
346 	struct nilfs_dir_entry *de;
347 
348 	if (npages == 0)
349 		goto out;
350 
351 	/* OFFSET_CACHE */
352 	*res_page = NULL;
353 
354 	start = ei->i_dir_start_lookup;
355 	if (start >= npages)
356 		start = 0;
357 	n = start;
358 	do {
359 		char *kaddr;
360 		page = nilfs_get_page(dir, n);
361 		if (!IS_ERR(page)) {
362 			kaddr = page_address(page);
363 			de = (struct nilfs_dir_entry *)kaddr;
364 			kaddr += nilfs_last_byte(dir, n) - reclen;
365 			while ((char *) de <= kaddr) {
366 				if (de->rec_len == 0) {
367 					nilfs_error(dir->i_sb, __func__,
368 						"zero-length directory entry");
369 					nilfs_put_page(page);
370 					goto out;
371 				}
372 				if (nilfs_match(namelen, name, de))
373 					goto found;
374 				de = nilfs_next_entry(de);
375 			}
376 			nilfs_put_page(page);
377 		}
378 		if (++n >= npages)
379 			n = 0;
380 		/* next page is past the blocks we've got */
381 		if (unlikely(n > (dir->i_blocks >> (PAGE_CACHE_SHIFT - 9)))) {
382 			nilfs_error(dir->i_sb, __func__,
383 			       "dir %lu size %lld exceeds block count %llu",
384 			       dir->i_ino, dir->i_size,
385 			       (unsigned long long)dir->i_blocks);
386 			goto out;
387 		}
388 	} while (n != start);
389 out:
390 	return NULL;
391 
392 found:
393 	*res_page = page;
394 	ei->i_dir_start_lookup = n;
395 	return de;
396 }
397 
398 struct nilfs_dir_entry *nilfs_dotdot(struct inode *dir, struct page **p)
399 {
400 	struct page *page = nilfs_get_page(dir, 0);
401 	struct nilfs_dir_entry *de = NULL;
402 
403 	if (!IS_ERR(page)) {
404 		de = nilfs_next_entry(
405 			(struct nilfs_dir_entry *)page_address(page));
406 		*p = page;
407 	}
408 	return de;
409 }
410 
411 ino_t nilfs_inode_by_name(struct inode *dir, const struct qstr *qstr)
412 {
413 	ino_t res = 0;
414 	struct nilfs_dir_entry *de;
415 	struct page *page;
416 
417 	de = nilfs_find_entry(dir, qstr, &page);
418 	if (de) {
419 		res = le64_to_cpu(de->inode);
420 		kunmap(page);
421 		page_cache_release(page);
422 	}
423 	return res;
424 }
425 
426 /* Releases the page */
427 void nilfs_set_link(struct inode *dir, struct nilfs_dir_entry *de,
428 		    struct page *page, struct inode *inode)
429 {
430 	unsigned from = (char *) de - (char *) page_address(page);
431 	unsigned to = from + nilfs_rec_len_from_disk(de->rec_len);
432 	struct address_space *mapping = page->mapping;
433 	int err;
434 
435 	lock_page(page);
436 	err = nilfs_prepare_chunk(page, from, to);
437 	BUG_ON(err);
438 	de->inode = cpu_to_le64(inode->i_ino);
439 	nilfs_set_de_type(de, inode);
440 	nilfs_commit_chunk(page, mapping, from, to);
441 	nilfs_put_page(page);
442 	dir->i_mtime = dir->i_ctime = CURRENT_TIME;
443 }
444 
445 /*
446  *	Parent is locked.
447  */
448 int nilfs_add_link(struct dentry *dentry, struct inode *inode)
449 {
450 	struct inode *dir = dentry->d_parent->d_inode;
451 	const unsigned char *name = dentry->d_name.name;
452 	int namelen = dentry->d_name.len;
453 	unsigned chunk_size = nilfs_chunk_size(dir);
454 	unsigned reclen = NILFS_DIR_REC_LEN(namelen);
455 	unsigned short rec_len, name_len;
456 	struct page *page = NULL;
457 	struct nilfs_dir_entry *de;
458 	unsigned long npages = dir_pages(dir);
459 	unsigned long n;
460 	char *kaddr;
461 	unsigned from, to;
462 	int err;
463 
464 	/*
465 	 * We take care of directory expansion in the same loop.
466 	 * This code plays outside i_size, so it locks the page
467 	 * to protect that region.
468 	 */
469 	for (n = 0; n <= npages; n++) {
470 		char *dir_end;
471 
472 		page = nilfs_get_page(dir, n);
473 		err = PTR_ERR(page);
474 		if (IS_ERR(page))
475 			goto out;
476 		lock_page(page);
477 		kaddr = page_address(page);
478 		dir_end = kaddr + nilfs_last_byte(dir, n);
479 		de = (struct nilfs_dir_entry *)kaddr;
480 		kaddr += PAGE_CACHE_SIZE - reclen;
481 		while ((char *)de <= kaddr) {
482 			if ((char *)de == dir_end) {
483 				/* We hit i_size */
484 				name_len = 0;
485 				rec_len = chunk_size;
486 				de->rec_len = nilfs_rec_len_to_disk(chunk_size);
487 				de->inode = 0;
488 				goto got_it;
489 			}
490 			if (de->rec_len == 0) {
491 				nilfs_error(dir->i_sb, __func__,
492 					    "zero-length directory entry");
493 				err = -EIO;
494 				goto out_unlock;
495 			}
496 			err = -EEXIST;
497 			if (nilfs_match(namelen, name, de))
498 				goto out_unlock;
499 			name_len = NILFS_DIR_REC_LEN(de->name_len);
500 			rec_len = nilfs_rec_len_from_disk(de->rec_len);
501 			if (!de->inode && rec_len >= reclen)
502 				goto got_it;
503 			if (rec_len >= name_len + reclen)
504 				goto got_it;
505 			de = (struct nilfs_dir_entry *)((char *)de + rec_len);
506 		}
507 		unlock_page(page);
508 		nilfs_put_page(page);
509 	}
510 	BUG();
511 	return -EINVAL;
512 
513 got_it:
514 	from = (char *)de - (char *)page_address(page);
515 	to = from + rec_len;
516 	err = nilfs_prepare_chunk(page, from, to);
517 	if (err)
518 		goto out_unlock;
519 	if (de->inode) {
520 		struct nilfs_dir_entry *de1;
521 
522 		de1 = (struct nilfs_dir_entry *)((char *)de + name_len);
523 		de1->rec_len = nilfs_rec_len_to_disk(rec_len - name_len);
524 		de->rec_len = nilfs_rec_len_to_disk(name_len);
525 		de = de1;
526 	}
527 	de->name_len = namelen;
528 	memcpy(de->name, name, namelen);
529 	de->inode = cpu_to_le64(inode->i_ino);
530 	nilfs_set_de_type(de, inode);
531 	nilfs_commit_chunk(page, page->mapping, from, to);
532 	dir->i_mtime = dir->i_ctime = CURRENT_TIME;
533 	nilfs_mark_inode_dirty(dir);
534 	/* OFFSET_CACHE */
535 out_put:
536 	nilfs_put_page(page);
537 out:
538 	return err;
539 out_unlock:
540 	unlock_page(page);
541 	goto out_put;
542 }
543 
544 /*
545  * nilfs_delete_entry deletes a directory entry by merging it with the
546  * previous entry. Page is up-to-date. Releases the page.
547  */
548 int nilfs_delete_entry(struct nilfs_dir_entry *dir, struct page *page)
549 {
550 	struct address_space *mapping = page->mapping;
551 	struct inode *inode = mapping->host;
552 	char *kaddr = page_address(page);
553 	unsigned from = ((char *)dir - kaddr) & ~(nilfs_chunk_size(inode) - 1);
554 	unsigned to = ((char *)dir - kaddr) +
555 		nilfs_rec_len_from_disk(dir->rec_len);
556 	struct nilfs_dir_entry *pde = NULL;
557 	struct nilfs_dir_entry *de = (struct nilfs_dir_entry *)(kaddr + from);
558 	int err;
559 
560 	while ((char *)de < (char *)dir) {
561 		if (de->rec_len == 0) {
562 			nilfs_error(inode->i_sb, __func__,
563 				    "zero-length directory entry");
564 			err = -EIO;
565 			goto out;
566 		}
567 		pde = de;
568 		de = nilfs_next_entry(de);
569 	}
570 	if (pde)
571 		from = (char *)pde - (char *)page_address(page);
572 	lock_page(page);
573 	err = nilfs_prepare_chunk(page, from, to);
574 	BUG_ON(err);
575 	if (pde)
576 		pde->rec_len = nilfs_rec_len_to_disk(to - from);
577 	dir->inode = 0;
578 	nilfs_commit_chunk(page, mapping, from, to);
579 	inode->i_ctime = inode->i_mtime = CURRENT_TIME;
580 out:
581 	nilfs_put_page(page);
582 	return err;
583 }
584 
585 /*
586  * Set the first fragment of directory.
587  */
588 int nilfs_make_empty(struct inode *inode, struct inode *parent)
589 {
590 	struct address_space *mapping = inode->i_mapping;
591 	struct page *page = grab_cache_page(mapping, 0);
592 	unsigned chunk_size = nilfs_chunk_size(inode);
593 	struct nilfs_dir_entry *de;
594 	int err;
595 	void *kaddr;
596 
597 	if (!page)
598 		return -ENOMEM;
599 
600 	err = nilfs_prepare_chunk(page, 0, chunk_size);
601 	if (unlikely(err)) {
602 		unlock_page(page);
603 		goto fail;
604 	}
605 	kaddr = kmap_atomic(page);
606 	memset(kaddr, 0, chunk_size);
607 	de = (struct nilfs_dir_entry *)kaddr;
608 	de->name_len = 1;
609 	de->rec_len = nilfs_rec_len_to_disk(NILFS_DIR_REC_LEN(1));
610 	memcpy(de->name, ".\0\0", 4);
611 	de->inode = cpu_to_le64(inode->i_ino);
612 	nilfs_set_de_type(de, inode);
613 
614 	de = (struct nilfs_dir_entry *)(kaddr + NILFS_DIR_REC_LEN(1));
615 	de->name_len = 2;
616 	de->rec_len = nilfs_rec_len_to_disk(chunk_size - NILFS_DIR_REC_LEN(1));
617 	de->inode = cpu_to_le64(parent->i_ino);
618 	memcpy(de->name, "..\0", 4);
619 	nilfs_set_de_type(de, inode);
620 	kunmap_atomic(kaddr);
621 	nilfs_commit_chunk(page, mapping, 0, chunk_size);
622 fail:
623 	page_cache_release(page);
624 	return err;
625 }
626 
627 /*
628  * routine to check that the specified directory is empty (for rmdir)
629  */
630 int nilfs_empty_dir(struct inode *inode)
631 {
632 	struct page *page = NULL;
633 	unsigned long i, npages = dir_pages(inode);
634 
635 	for (i = 0; i < npages; i++) {
636 		char *kaddr;
637 		struct nilfs_dir_entry *de;
638 
639 		page = nilfs_get_page(inode, i);
640 		if (IS_ERR(page))
641 			continue;
642 
643 		kaddr = page_address(page);
644 		de = (struct nilfs_dir_entry *)kaddr;
645 		kaddr += nilfs_last_byte(inode, i) - NILFS_DIR_REC_LEN(1);
646 
647 		while ((char *)de <= kaddr) {
648 			if (de->rec_len == 0) {
649 				nilfs_error(inode->i_sb, __func__,
650 					    "zero-length directory entry "
651 					    "(kaddr=%p, de=%p)\n", kaddr, de);
652 				goto not_empty;
653 			}
654 			if (de->inode != 0) {
655 				/* check for . and .. */
656 				if (de->name[0] != '.')
657 					goto not_empty;
658 				if (de->name_len > 2)
659 					goto not_empty;
660 				if (de->name_len < 2) {
661 					if (de->inode !=
662 					    cpu_to_le64(inode->i_ino))
663 						goto not_empty;
664 				} else if (de->name[1] != '.')
665 					goto not_empty;
666 			}
667 			de = nilfs_next_entry(de);
668 		}
669 		nilfs_put_page(page);
670 	}
671 	return 1;
672 
673 not_empty:
674 	nilfs_put_page(page);
675 	return 0;
676 }
677 
678 const struct file_operations nilfs_dir_operations = {
679 	.llseek		= generic_file_llseek,
680 	.read		= generic_read_dir,
681 	.readdir	= nilfs_readdir,
682 	.unlocked_ioctl	= nilfs_ioctl,
683 #ifdef CONFIG_COMPAT
684 	.compat_ioctl	= nilfs_compat_ioctl,
685 #endif	/* CONFIG_COMPAT */
686 	.fsync		= nilfs_sync_file,
687 
688 };
689