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1 /*
2  * Copyright (C) 2005, 2006
3  * Avishay Traeger (avishay@gmail.com)
4  * Copyright (C) 2008, 2009
5  * Boaz Harrosh <ooo@electrozaur.com>
6  *
7  * Copyrights for code taken from ext2:
8  *     Copyright (C) 1992, 1993, 1994, 1995
9  *     Remy Card (card@masi.ibp.fr)
10  *     Laboratoire MASI - Institut Blaise Pascal
11  *     Universite Pierre et Marie Curie (Paris VI)
12  *     from
13  *     linux/fs/minix/inode.c
14  *     Copyright (C) 1991, 1992  Linus Torvalds
15  *
16  * This file is part of exofs.
17  *
18  * exofs is free software; you can redistribute it and/or modify
19  * it under the terms of the GNU General Public License as published by
20  * the Free Software Foundation.  Since it is based on ext2, and the only
21  * valid version of GPL for the Linux kernel is version 2, the only valid
22  * version of GPL for exofs is version 2.
23  *
24  * exofs is distributed in the hope that it will be useful,
25  * but WITHOUT ANY WARRANTY; without even the implied warranty of
26  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
27  * GNU General Public License for more details.
28  *
29  * You should have received a copy of the GNU General Public License
30  * along with exofs; if not, write to the Free Software
31  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
32  */
33 
34 #include "exofs.h"
35 
exofs_chunk_size(struct inode * inode)36 static inline unsigned exofs_chunk_size(struct inode *inode)
37 {
38 	return inode->i_sb->s_blocksize;
39 }
40 
exofs_put_page(struct page * page)41 static inline void exofs_put_page(struct page *page)
42 {
43 	kunmap(page);
44 	put_page(page);
45 }
46 
exofs_last_byte(struct inode * inode,unsigned long page_nr)47 static unsigned exofs_last_byte(struct inode *inode, unsigned long page_nr)
48 {
49 	loff_t last_byte = inode->i_size;
50 
51 	last_byte -= page_nr << PAGE_SHIFT;
52 	if (last_byte > PAGE_SIZE)
53 		last_byte = PAGE_SIZE;
54 	return last_byte;
55 }
56 
exofs_commit_chunk(struct page * page,loff_t pos,unsigned len)57 static int exofs_commit_chunk(struct page *page, loff_t pos, unsigned len)
58 {
59 	struct address_space *mapping = page->mapping;
60 	struct inode *dir = mapping->host;
61 	int err = 0;
62 
63 	dir->i_version++;
64 
65 	if (!PageUptodate(page))
66 		SetPageUptodate(page);
67 
68 	if (pos+len > dir->i_size) {
69 		i_size_write(dir, pos+len);
70 		mark_inode_dirty(dir);
71 	}
72 	set_page_dirty(page);
73 
74 	if (IS_DIRSYNC(dir))
75 		err = write_one_page(page, 1);
76 	else
77 		unlock_page(page);
78 
79 	return err;
80 }
81 
exofs_check_page(struct page * page)82 static bool exofs_check_page(struct page *page)
83 {
84 	struct inode *dir = page->mapping->host;
85 	unsigned chunk_size = exofs_chunk_size(dir);
86 	char *kaddr = page_address(page);
87 	unsigned offs, rec_len;
88 	unsigned limit = PAGE_SIZE;
89 	struct exofs_dir_entry *p;
90 	char *error;
91 
92 	/* if the page is the last one in the directory */
93 	if ((dir->i_size >> PAGE_SHIFT) == page->index) {
94 		limit = dir->i_size & ~PAGE_MASK;
95 		if (limit & (chunk_size - 1))
96 			goto Ebadsize;
97 		if (!limit)
98 			goto out;
99 	}
100 	for (offs = 0; offs <= limit - EXOFS_DIR_REC_LEN(1); offs += rec_len) {
101 		p = (struct exofs_dir_entry *)(kaddr + offs);
102 		rec_len = le16_to_cpu(p->rec_len);
103 
104 		if (rec_len < EXOFS_DIR_REC_LEN(1))
105 			goto Eshort;
106 		if (rec_len & 3)
107 			goto Ealign;
108 		if (rec_len < EXOFS_DIR_REC_LEN(p->name_len))
109 			goto Enamelen;
110 		if (((offs + rec_len - 1) ^ offs) & ~(chunk_size-1))
111 			goto Espan;
112 	}
113 	if (offs != limit)
114 		goto Eend;
115 out:
116 	SetPageChecked(page);
117 	return true;
118 
119 Ebadsize:
120 	EXOFS_ERR("ERROR [exofs_check_page]: "
121 		"size of directory(0x%lx) is not a multiple of chunk size\n",
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 bad_entry:
138 	EXOFS_ERR(
139 		"ERROR [exofs_check_page]: bad entry in directory(0x%lx): %s - "
140 		"offset=%lu, inode=0x%llx, rec_len=%d, name_len=%d\n",
141 		dir->i_ino, error, (page->index<<PAGE_SHIFT)+offs,
142 		_LLU(le64_to_cpu(p->inode_no)),
143 		rec_len, p->name_len);
144 	goto fail;
145 Eend:
146 	p = (struct exofs_dir_entry *)(kaddr + offs);
147 	EXOFS_ERR("ERROR [exofs_check_page]: "
148 		"entry in directory(0x%lx) spans the page boundary"
149 		"offset=%lu, inode=0x%llx\n",
150 		dir->i_ino, (page->index<<PAGE_SHIFT)+offs,
151 		_LLU(le64_to_cpu(p->inode_no)));
152 fail:
153 	SetPageError(page);
154 	return false;
155 }
156 
exofs_get_page(struct inode * dir,unsigned long n)157 static struct page *exofs_get_page(struct inode *dir, unsigned long n)
158 {
159 	struct address_space *mapping = dir->i_mapping;
160 	struct page *page = read_mapping_page(mapping, n, NULL);
161 
162 	if (!IS_ERR(page)) {
163 		kmap(page);
164 		if (unlikely(!PageChecked(page))) {
165 			if (PageError(page) || !exofs_check_page(page))
166 				goto fail;
167 		}
168 	}
169 	return page;
170 
171 fail:
172 	exofs_put_page(page);
173 	return ERR_PTR(-EIO);
174 }
175 
exofs_match(int len,const unsigned char * name,struct exofs_dir_entry * de)176 static inline int exofs_match(int len, const unsigned char *name,
177 					struct exofs_dir_entry *de)
178 {
179 	if (len != de->name_len)
180 		return 0;
181 	if (!de->inode_no)
182 		return 0;
183 	return !memcmp(name, de->name, len);
184 }
185 
186 static inline
exofs_next_entry(struct exofs_dir_entry * p)187 struct exofs_dir_entry *exofs_next_entry(struct exofs_dir_entry *p)
188 {
189 	return (struct exofs_dir_entry *)((char *)p + le16_to_cpu(p->rec_len));
190 }
191 
192 static inline unsigned
exofs_validate_entry(char * base,unsigned offset,unsigned mask)193 exofs_validate_entry(char *base, unsigned offset, unsigned mask)
194 {
195 	struct exofs_dir_entry *de = (struct exofs_dir_entry *)(base + offset);
196 	struct exofs_dir_entry *p =
197 			(struct exofs_dir_entry *)(base + (offset&mask));
198 	while ((char *)p < (char *)de) {
199 		if (p->rec_len == 0)
200 			break;
201 		p = exofs_next_entry(p);
202 	}
203 	return (char *)p - base;
204 }
205 
206 static unsigned char exofs_filetype_table[EXOFS_FT_MAX] = {
207 	[EXOFS_FT_UNKNOWN]	= DT_UNKNOWN,
208 	[EXOFS_FT_REG_FILE]	= DT_REG,
209 	[EXOFS_FT_DIR]		= DT_DIR,
210 	[EXOFS_FT_CHRDEV]	= DT_CHR,
211 	[EXOFS_FT_BLKDEV]	= DT_BLK,
212 	[EXOFS_FT_FIFO]		= DT_FIFO,
213 	[EXOFS_FT_SOCK]		= DT_SOCK,
214 	[EXOFS_FT_SYMLINK]	= DT_LNK,
215 };
216 
217 #define S_SHIFT 12
218 static unsigned char exofs_type_by_mode[S_IFMT >> S_SHIFT] = {
219 	[S_IFREG >> S_SHIFT]	= EXOFS_FT_REG_FILE,
220 	[S_IFDIR >> S_SHIFT]	= EXOFS_FT_DIR,
221 	[S_IFCHR >> S_SHIFT]	= EXOFS_FT_CHRDEV,
222 	[S_IFBLK >> S_SHIFT]	= EXOFS_FT_BLKDEV,
223 	[S_IFIFO >> S_SHIFT]	= EXOFS_FT_FIFO,
224 	[S_IFSOCK >> S_SHIFT]	= EXOFS_FT_SOCK,
225 	[S_IFLNK >> S_SHIFT]	= EXOFS_FT_SYMLINK,
226 };
227 
228 static inline
exofs_set_de_type(struct exofs_dir_entry * de,struct inode * inode)229 void exofs_set_de_type(struct exofs_dir_entry *de, struct inode *inode)
230 {
231 	umode_t mode = inode->i_mode;
232 	de->file_type = exofs_type_by_mode[(mode & S_IFMT) >> S_SHIFT];
233 }
234 
235 static int
exofs_readdir(struct file * file,struct dir_context * ctx)236 exofs_readdir(struct file *file, struct dir_context *ctx)
237 {
238 	loff_t pos = ctx->pos;
239 	struct inode *inode = file_inode(file);
240 	unsigned int offset = pos & ~PAGE_MASK;
241 	unsigned long n = pos >> PAGE_SHIFT;
242 	unsigned long npages = dir_pages(inode);
243 	unsigned chunk_mask = ~(exofs_chunk_size(inode)-1);
244 	int need_revalidate = (file->f_version != inode->i_version);
245 
246 	if (pos > inode->i_size - EXOFS_DIR_REC_LEN(1))
247 		return 0;
248 
249 	for ( ; n < npages; n++, offset = 0) {
250 		char *kaddr, *limit;
251 		struct exofs_dir_entry *de;
252 		struct page *page = exofs_get_page(inode, n);
253 
254 		if (IS_ERR(page)) {
255 			EXOFS_ERR("ERROR: bad page in directory(0x%lx)\n",
256 				  inode->i_ino);
257 			ctx->pos += PAGE_SIZE - offset;
258 			return PTR_ERR(page);
259 		}
260 		kaddr = page_address(page);
261 		if (unlikely(need_revalidate)) {
262 			if (offset) {
263 				offset = exofs_validate_entry(kaddr, offset,
264 								chunk_mask);
265 				ctx->pos = (n<<PAGE_SHIFT) + offset;
266 			}
267 			file->f_version = inode->i_version;
268 			need_revalidate = 0;
269 		}
270 		de = (struct exofs_dir_entry *)(kaddr + offset);
271 		limit = kaddr + exofs_last_byte(inode, n) -
272 							EXOFS_DIR_REC_LEN(1);
273 		for (; (char *)de <= limit; de = exofs_next_entry(de)) {
274 			if (de->rec_len == 0) {
275 				EXOFS_ERR("ERROR: "
276 				     "zero-length entry in directory(0x%lx)\n",
277 				     inode->i_ino);
278 				exofs_put_page(page);
279 				return -EIO;
280 			}
281 			if (de->inode_no) {
282 				unsigned char t;
283 
284 				if (de->file_type < EXOFS_FT_MAX)
285 					t = exofs_filetype_table[de->file_type];
286 				else
287 					t = DT_UNKNOWN;
288 
289 				if (!dir_emit(ctx, de->name, de->name_len,
290 						le64_to_cpu(de->inode_no),
291 						t)) {
292 					exofs_put_page(page);
293 					return 0;
294 				}
295 			}
296 			ctx->pos += le16_to_cpu(de->rec_len);
297 		}
298 		exofs_put_page(page);
299 	}
300 	return 0;
301 }
302 
exofs_find_entry(struct inode * dir,struct dentry * dentry,struct page ** res_page)303 struct exofs_dir_entry *exofs_find_entry(struct inode *dir,
304 			struct dentry *dentry, struct page **res_page)
305 {
306 	const unsigned char *name = dentry->d_name.name;
307 	int namelen = dentry->d_name.len;
308 	unsigned reclen = EXOFS_DIR_REC_LEN(namelen);
309 	unsigned long start, n;
310 	unsigned long npages = dir_pages(dir);
311 	struct page *page = NULL;
312 	struct exofs_i_info *oi = exofs_i(dir);
313 	struct exofs_dir_entry *de;
314 
315 	if (npages == 0)
316 		goto out;
317 
318 	*res_page = NULL;
319 
320 	start = oi->i_dir_start_lookup;
321 	if (start >= npages)
322 		start = 0;
323 	n = start;
324 	do {
325 		char *kaddr;
326 		page = exofs_get_page(dir, n);
327 		if (!IS_ERR(page)) {
328 			kaddr = page_address(page);
329 			de = (struct exofs_dir_entry *) kaddr;
330 			kaddr += exofs_last_byte(dir, n) - reclen;
331 			while ((char *) de <= kaddr) {
332 				if (de->rec_len == 0) {
333 					EXOFS_ERR("ERROR: zero-length entry in "
334 						  "directory(0x%lx)\n",
335 						  dir->i_ino);
336 					exofs_put_page(page);
337 					goto out;
338 				}
339 				if (exofs_match(namelen, name, de))
340 					goto found;
341 				de = exofs_next_entry(de);
342 			}
343 			exofs_put_page(page);
344 		}
345 		if (++n >= npages)
346 			n = 0;
347 	} while (n != start);
348 out:
349 	return NULL;
350 
351 found:
352 	*res_page = page;
353 	oi->i_dir_start_lookup = n;
354 	return de;
355 }
356 
exofs_dotdot(struct inode * dir,struct page ** p)357 struct exofs_dir_entry *exofs_dotdot(struct inode *dir, struct page **p)
358 {
359 	struct page *page = exofs_get_page(dir, 0);
360 	struct exofs_dir_entry *de = NULL;
361 
362 	if (!IS_ERR(page)) {
363 		de = exofs_next_entry(
364 				(struct exofs_dir_entry *)page_address(page));
365 		*p = page;
366 	}
367 	return de;
368 }
369 
exofs_parent_ino(struct dentry * child)370 ino_t exofs_parent_ino(struct dentry *child)
371 {
372 	struct page *page;
373 	struct exofs_dir_entry *de;
374 	ino_t ino;
375 
376 	de = exofs_dotdot(d_inode(child), &page);
377 	if (!de)
378 		return 0;
379 
380 	ino = le64_to_cpu(de->inode_no);
381 	exofs_put_page(page);
382 	return ino;
383 }
384 
exofs_inode_by_name(struct inode * dir,struct dentry * dentry)385 ino_t exofs_inode_by_name(struct inode *dir, struct dentry *dentry)
386 {
387 	ino_t res = 0;
388 	struct exofs_dir_entry *de;
389 	struct page *page;
390 
391 	de = exofs_find_entry(dir, dentry, &page);
392 	if (de) {
393 		res = le64_to_cpu(de->inode_no);
394 		exofs_put_page(page);
395 	}
396 	return res;
397 }
398 
exofs_set_link(struct inode * dir,struct exofs_dir_entry * de,struct page * page,struct inode * inode)399 int exofs_set_link(struct inode *dir, struct exofs_dir_entry *de,
400 			struct page *page, struct inode *inode)
401 {
402 	loff_t pos = page_offset(page) +
403 			(char *) de - (char *) page_address(page);
404 	unsigned len = le16_to_cpu(de->rec_len);
405 	int err;
406 
407 	lock_page(page);
408 	err = exofs_write_begin(NULL, page->mapping, pos, len,
409 				AOP_FLAG_UNINTERRUPTIBLE, &page, NULL);
410 	if (err)
411 		EXOFS_ERR("exofs_set_link: exofs_write_begin FAILED => %d\n",
412 			  err);
413 
414 	de->inode_no = cpu_to_le64(inode->i_ino);
415 	exofs_set_de_type(de, inode);
416 	if (likely(!err))
417 		err = exofs_commit_chunk(page, pos, len);
418 	exofs_put_page(page);
419 	dir->i_mtime = dir->i_ctime = current_time(dir);
420 	mark_inode_dirty(dir);
421 	return err;
422 }
423 
exofs_add_link(struct dentry * dentry,struct inode * inode)424 int exofs_add_link(struct dentry *dentry, struct inode *inode)
425 {
426 	struct inode *dir = d_inode(dentry->d_parent);
427 	const unsigned char *name = dentry->d_name.name;
428 	int namelen = dentry->d_name.len;
429 	unsigned chunk_size = exofs_chunk_size(dir);
430 	unsigned reclen = EXOFS_DIR_REC_LEN(namelen);
431 	unsigned short rec_len, name_len;
432 	struct page *page = NULL;
433 	struct exofs_sb_info *sbi = inode->i_sb->s_fs_info;
434 	struct exofs_dir_entry *de;
435 	unsigned long npages = dir_pages(dir);
436 	unsigned long n;
437 	char *kaddr;
438 	loff_t pos;
439 	int err;
440 
441 	for (n = 0; n <= npages; n++) {
442 		char *dir_end;
443 
444 		page = exofs_get_page(dir, n);
445 		err = PTR_ERR(page);
446 		if (IS_ERR(page))
447 			goto out;
448 		lock_page(page);
449 		kaddr = page_address(page);
450 		dir_end = kaddr + exofs_last_byte(dir, n);
451 		de = (struct exofs_dir_entry *)kaddr;
452 		kaddr += PAGE_SIZE - reclen;
453 		while ((char *)de <= kaddr) {
454 			if ((char *)de == dir_end) {
455 				name_len = 0;
456 				rec_len = chunk_size;
457 				de->rec_len = cpu_to_le16(chunk_size);
458 				de->inode_no = 0;
459 				goto got_it;
460 			}
461 			if (de->rec_len == 0) {
462 				EXOFS_ERR("ERROR: exofs_add_link: "
463 				      "zero-length entry in directory(0x%lx)\n",
464 				      inode->i_ino);
465 				err = -EIO;
466 				goto out_unlock;
467 			}
468 			err = -EEXIST;
469 			if (exofs_match(namelen, name, de))
470 				goto out_unlock;
471 			name_len = EXOFS_DIR_REC_LEN(de->name_len);
472 			rec_len = le16_to_cpu(de->rec_len);
473 			if (!de->inode_no && rec_len >= reclen)
474 				goto got_it;
475 			if (rec_len >= name_len + reclen)
476 				goto got_it;
477 			de = (struct exofs_dir_entry *) ((char *) de + rec_len);
478 		}
479 		unlock_page(page);
480 		exofs_put_page(page);
481 	}
482 
483 	EXOFS_ERR("exofs_add_link: BAD dentry=%p or inode=0x%lx\n",
484 		  dentry, inode->i_ino);
485 	return -EINVAL;
486 
487 got_it:
488 	pos = page_offset(page) +
489 		(char *)de - (char *)page_address(page);
490 	err = exofs_write_begin(NULL, page->mapping, pos, rec_len, 0,
491 							&page, NULL);
492 	if (err)
493 		goto out_unlock;
494 	if (de->inode_no) {
495 		struct exofs_dir_entry *de1 =
496 			(struct exofs_dir_entry *)((char *)de + name_len);
497 		de1->rec_len = cpu_to_le16(rec_len - name_len);
498 		de->rec_len = cpu_to_le16(name_len);
499 		de = de1;
500 	}
501 	de->name_len = namelen;
502 	memcpy(de->name, name, namelen);
503 	de->inode_no = cpu_to_le64(inode->i_ino);
504 	exofs_set_de_type(de, inode);
505 	err = exofs_commit_chunk(page, pos, rec_len);
506 	dir->i_mtime = dir->i_ctime = current_time(dir);
507 	mark_inode_dirty(dir);
508 	sbi->s_numfiles++;
509 
510 out_put:
511 	exofs_put_page(page);
512 out:
513 	return err;
514 out_unlock:
515 	unlock_page(page);
516 	goto out_put;
517 }
518 
exofs_delete_entry(struct exofs_dir_entry * dir,struct page * page)519 int exofs_delete_entry(struct exofs_dir_entry *dir, struct page *page)
520 {
521 	struct address_space *mapping = page->mapping;
522 	struct inode *inode = mapping->host;
523 	struct exofs_sb_info *sbi = inode->i_sb->s_fs_info;
524 	char *kaddr = page_address(page);
525 	unsigned from = ((char *)dir - kaddr) & ~(exofs_chunk_size(inode)-1);
526 	unsigned to = ((char *)dir - kaddr) + le16_to_cpu(dir->rec_len);
527 	loff_t pos;
528 	struct exofs_dir_entry *pde = NULL;
529 	struct exofs_dir_entry *de = (struct exofs_dir_entry *) (kaddr + from);
530 	int err;
531 
532 	while (de < dir) {
533 		if (de->rec_len == 0) {
534 			EXOFS_ERR("ERROR: exofs_delete_entry:"
535 				  "zero-length entry in directory(0x%lx)\n",
536 				  inode->i_ino);
537 			err = -EIO;
538 			goto out;
539 		}
540 		pde = de;
541 		de = exofs_next_entry(de);
542 	}
543 	if (pde)
544 		from = (char *)pde - (char *)page_address(page);
545 	pos = page_offset(page) + from;
546 	lock_page(page);
547 	err = exofs_write_begin(NULL, page->mapping, pos, to - from, 0,
548 							&page, NULL);
549 	if (err)
550 		EXOFS_ERR("exofs_delete_entry: exofs_write_begin FAILED => %d\n",
551 			  err);
552 	if (pde)
553 		pde->rec_len = cpu_to_le16(to - from);
554 	dir->inode_no = 0;
555 	if (likely(!err))
556 		err = exofs_commit_chunk(page, pos, to - from);
557 	inode->i_ctime = inode->i_mtime = current_time(inode);
558 	mark_inode_dirty(inode);
559 	sbi->s_numfiles--;
560 out:
561 	exofs_put_page(page);
562 	return err;
563 }
564 
565 /* kept aligned on 4 bytes */
566 #define THIS_DIR ".\0\0"
567 #define PARENT_DIR "..\0"
568 
exofs_make_empty(struct inode * inode,struct inode * parent)569 int exofs_make_empty(struct inode *inode, struct inode *parent)
570 {
571 	struct address_space *mapping = inode->i_mapping;
572 	struct page *page = grab_cache_page(mapping, 0);
573 	unsigned chunk_size = exofs_chunk_size(inode);
574 	struct exofs_dir_entry *de;
575 	int err;
576 	void *kaddr;
577 
578 	if (!page)
579 		return -ENOMEM;
580 
581 	err = exofs_write_begin(NULL, page->mapping, 0, chunk_size, 0,
582 							&page, NULL);
583 	if (err) {
584 		unlock_page(page);
585 		goto fail;
586 	}
587 
588 	kaddr = kmap_atomic(page);
589 	de = (struct exofs_dir_entry *)kaddr;
590 	de->name_len = 1;
591 	de->rec_len = cpu_to_le16(EXOFS_DIR_REC_LEN(1));
592 	memcpy(de->name, THIS_DIR, sizeof(THIS_DIR));
593 	de->inode_no = cpu_to_le64(inode->i_ino);
594 	exofs_set_de_type(de, inode);
595 
596 	de = (struct exofs_dir_entry *)(kaddr + EXOFS_DIR_REC_LEN(1));
597 	de->name_len = 2;
598 	de->rec_len = cpu_to_le16(chunk_size - EXOFS_DIR_REC_LEN(1));
599 	de->inode_no = cpu_to_le64(parent->i_ino);
600 	memcpy(de->name, PARENT_DIR, sizeof(PARENT_DIR));
601 	exofs_set_de_type(de, inode);
602 	kunmap_atomic(kaddr);
603 	err = exofs_commit_chunk(page, 0, chunk_size);
604 fail:
605 	put_page(page);
606 	return err;
607 }
608 
exofs_empty_dir(struct inode * inode)609 int exofs_empty_dir(struct inode *inode)
610 {
611 	struct page *page = NULL;
612 	unsigned long i, npages = dir_pages(inode);
613 
614 	for (i = 0; i < npages; i++) {
615 		char *kaddr;
616 		struct exofs_dir_entry *de;
617 		page = exofs_get_page(inode, i);
618 
619 		if (IS_ERR(page))
620 			continue;
621 
622 		kaddr = page_address(page);
623 		de = (struct exofs_dir_entry *)kaddr;
624 		kaddr += exofs_last_byte(inode, i) - EXOFS_DIR_REC_LEN(1);
625 
626 		while ((char *)de <= kaddr) {
627 			if (de->rec_len == 0) {
628 				EXOFS_ERR("ERROR: exofs_empty_dir: "
629 					  "zero-length directory entry"
630 					  "kaddr=%p, de=%p\n", kaddr, de);
631 				goto not_empty;
632 			}
633 			if (de->inode_no != 0) {
634 				/* check for . and .. */
635 				if (de->name[0] != '.')
636 					goto not_empty;
637 				if (de->name_len > 2)
638 					goto not_empty;
639 				if (de->name_len < 2) {
640 					if (le64_to_cpu(de->inode_no) !=
641 					    inode->i_ino)
642 						goto not_empty;
643 				} else if (de->name[1] != '.')
644 					goto not_empty;
645 			}
646 			de = exofs_next_entry(de);
647 		}
648 		exofs_put_page(page);
649 	}
650 	return 1;
651 
652 not_empty:
653 	exofs_put_page(page);
654 	return 0;
655 }
656 
657 const struct file_operations exofs_dir_operations = {
658 	.llseek		= generic_file_llseek,
659 	.read		= generic_read_dir,
660 	.iterate_shared	= exofs_readdir,
661 };
662