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1 /*
2  * Copyright (C) 2005, 2006
3  * Avishay Traeger (avishay@gmail.com)
4  * Copyright (C) 2008, 2009
5  * Boaz Harrosh <bharrosh@panasas.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 	page_cache_release(page);
45 }
46 
47 /* Accesses dir's inode->i_size must be called under inode lock */
dir_pages(struct inode * inode)48 static inline unsigned long dir_pages(struct inode *inode)
49 {
50 	return (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
51 }
52 
exofs_last_byte(struct inode * inode,unsigned long page_nr)53 static unsigned exofs_last_byte(struct inode *inode, unsigned long page_nr)
54 {
55 	loff_t last_byte = inode->i_size;
56 
57 	last_byte -= page_nr << PAGE_CACHE_SHIFT;
58 	if (last_byte > PAGE_CACHE_SIZE)
59 		last_byte = PAGE_CACHE_SIZE;
60 	return last_byte;
61 }
62 
exofs_commit_chunk(struct page * page,loff_t pos,unsigned len)63 static int exofs_commit_chunk(struct page *page, loff_t pos, unsigned len)
64 {
65 	struct address_space *mapping = page->mapping;
66 	struct inode *dir = mapping->host;
67 	int err = 0;
68 
69 	dir->i_version++;
70 
71 	if (!PageUptodate(page))
72 		SetPageUptodate(page);
73 
74 	if (pos+len > dir->i_size) {
75 		i_size_write(dir, pos+len);
76 		mark_inode_dirty(dir);
77 	}
78 	set_page_dirty(page);
79 
80 	if (IS_DIRSYNC(dir))
81 		err = write_one_page(page, 1);
82 	else
83 		unlock_page(page);
84 
85 	return err;
86 }
87 
exofs_check_page(struct page * page)88 static void exofs_check_page(struct page *page)
89 {
90 	struct inode *dir = page->mapping->host;
91 	unsigned chunk_size = exofs_chunk_size(dir);
92 	char *kaddr = page_address(page);
93 	unsigned offs, rec_len;
94 	unsigned limit = PAGE_CACHE_SIZE;
95 	struct exofs_dir_entry *p;
96 	char *error;
97 
98 	/* if the page is the last one in the directory */
99 	if ((dir->i_size >> PAGE_CACHE_SHIFT) == page->index) {
100 		limit = dir->i_size & ~PAGE_CACHE_MASK;
101 		if (limit & (chunk_size - 1))
102 			goto Ebadsize;
103 		if (!limit)
104 			goto out;
105 	}
106 	for (offs = 0; offs <= limit - EXOFS_DIR_REC_LEN(1); offs += rec_len) {
107 		p = (struct exofs_dir_entry *)(kaddr + offs);
108 		rec_len = le16_to_cpu(p->rec_len);
109 
110 		if (rec_len < EXOFS_DIR_REC_LEN(1))
111 			goto Eshort;
112 		if (rec_len & 3)
113 			goto Ealign;
114 		if (rec_len < EXOFS_DIR_REC_LEN(p->name_len))
115 			goto Enamelen;
116 		if (((offs + rec_len - 1) ^ offs) & ~(chunk_size-1))
117 			goto Espan;
118 	}
119 	if (offs != limit)
120 		goto Eend;
121 out:
122 	SetPageChecked(page);
123 	return;
124 
125 Ebadsize:
126 	EXOFS_ERR("ERROR [exofs_check_page]: "
127 		"size of directory(0x%lx) is not a multiple of chunk size\n",
128 		dir->i_ino
129 	);
130 	goto fail;
131 Eshort:
132 	error = "rec_len is smaller than minimal";
133 	goto bad_entry;
134 Ealign:
135 	error = "unaligned directory entry";
136 	goto bad_entry;
137 Enamelen:
138 	error = "rec_len is too small for name_len";
139 	goto bad_entry;
140 Espan:
141 	error = "directory entry across blocks";
142 	goto bad_entry;
143 bad_entry:
144 	EXOFS_ERR(
145 		"ERROR [exofs_check_page]: bad entry in directory(0x%lx): %s - "
146 		"offset=%lu, inode=0x%llu, rec_len=%d, name_len=%d\n",
147 		dir->i_ino, error, (page->index<<PAGE_CACHE_SHIFT)+offs,
148 		_LLU(le64_to_cpu(p->inode_no)),
149 		rec_len, p->name_len);
150 	goto fail;
151 Eend:
152 	p = (struct exofs_dir_entry *)(kaddr + offs);
153 	EXOFS_ERR("ERROR [exofs_check_page]: "
154 		"entry in directory(0x%lx) spans the page boundary"
155 		"offset=%lu, inode=0x%llx\n",
156 		dir->i_ino, (page->index<<PAGE_CACHE_SHIFT)+offs,
157 		_LLU(le64_to_cpu(p->inode_no)));
158 fail:
159 	SetPageChecked(page);
160 	SetPageError(page);
161 }
162 
exofs_get_page(struct inode * dir,unsigned long n)163 static struct page *exofs_get_page(struct inode *dir, unsigned long n)
164 {
165 	struct address_space *mapping = dir->i_mapping;
166 	struct page *page = read_mapping_page(mapping, n, NULL);
167 
168 	if (!IS_ERR(page)) {
169 		kmap(page);
170 		if (!PageChecked(page))
171 			exofs_check_page(page);
172 		if (PageError(page))
173 			goto fail;
174 	}
175 	return page;
176 
177 fail:
178 	exofs_put_page(page);
179 	return ERR_PTR(-EIO);
180 }
181 
exofs_match(int len,const unsigned char * name,struct exofs_dir_entry * de)182 static inline int exofs_match(int len, const unsigned char *name,
183 					struct exofs_dir_entry *de)
184 {
185 	if (len != de->name_len)
186 		return 0;
187 	if (!de->inode_no)
188 		return 0;
189 	return !memcmp(name, de->name, len);
190 }
191 
192 static inline
exofs_next_entry(struct exofs_dir_entry * p)193 struct exofs_dir_entry *exofs_next_entry(struct exofs_dir_entry *p)
194 {
195 	return (struct exofs_dir_entry *)((char *)p + le16_to_cpu(p->rec_len));
196 }
197 
198 static inline unsigned
exofs_validate_entry(char * base,unsigned offset,unsigned mask)199 exofs_validate_entry(char *base, unsigned offset, unsigned mask)
200 {
201 	struct exofs_dir_entry *de = (struct exofs_dir_entry *)(base + offset);
202 	struct exofs_dir_entry *p =
203 			(struct exofs_dir_entry *)(base + (offset&mask));
204 	while ((char *)p < (char *)de) {
205 		if (p->rec_len == 0)
206 			break;
207 		p = exofs_next_entry(p);
208 	}
209 	return (char *)p - base;
210 }
211 
212 static unsigned char exofs_filetype_table[EXOFS_FT_MAX] = {
213 	[EXOFS_FT_UNKNOWN]	= DT_UNKNOWN,
214 	[EXOFS_FT_REG_FILE]	= DT_REG,
215 	[EXOFS_FT_DIR]		= DT_DIR,
216 	[EXOFS_FT_CHRDEV]	= DT_CHR,
217 	[EXOFS_FT_BLKDEV]	= DT_BLK,
218 	[EXOFS_FT_FIFO]		= DT_FIFO,
219 	[EXOFS_FT_SOCK]		= DT_SOCK,
220 	[EXOFS_FT_SYMLINK]	= DT_LNK,
221 };
222 
223 #define S_SHIFT 12
224 static unsigned char exofs_type_by_mode[S_IFMT >> S_SHIFT] = {
225 	[S_IFREG >> S_SHIFT]	= EXOFS_FT_REG_FILE,
226 	[S_IFDIR >> S_SHIFT]	= EXOFS_FT_DIR,
227 	[S_IFCHR >> S_SHIFT]	= EXOFS_FT_CHRDEV,
228 	[S_IFBLK >> S_SHIFT]	= EXOFS_FT_BLKDEV,
229 	[S_IFIFO >> S_SHIFT]	= EXOFS_FT_FIFO,
230 	[S_IFSOCK >> S_SHIFT]	= EXOFS_FT_SOCK,
231 	[S_IFLNK >> S_SHIFT]	= EXOFS_FT_SYMLINK,
232 };
233 
234 static inline
exofs_set_de_type(struct exofs_dir_entry * de,struct inode * inode)235 void exofs_set_de_type(struct exofs_dir_entry *de, struct inode *inode)
236 {
237 	umode_t mode = inode->i_mode;
238 	de->file_type = exofs_type_by_mode[(mode & S_IFMT) >> S_SHIFT];
239 }
240 
241 static int
exofs_readdir(struct file * filp,void * dirent,filldir_t filldir)242 exofs_readdir(struct file *filp, void *dirent, filldir_t filldir)
243 {
244 	loff_t pos = filp->f_pos;
245 	struct inode *inode = filp->f_path.dentry->d_inode;
246 	unsigned int offset = pos & ~PAGE_CACHE_MASK;
247 	unsigned long n = pos >> PAGE_CACHE_SHIFT;
248 	unsigned long npages = dir_pages(inode);
249 	unsigned chunk_mask = ~(exofs_chunk_size(inode)-1);
250 	unsigned char *types = NULL;
251 	int need_revalidate = (filp->f_version != inode->i_version);
252 
253 	if (pos > inode->i_size - EXOFS_DIR_REC_LEN(1))
254 		return 0;
255 
256 	types = exofs_filetype_table;
257 
258 	for ( ; n < npages; n++, offset = 0) {
259 		char *kaddr, *limit;
260 		struct exofs_dir_entry *de;
261 		struct page *page = exofs_get_page(inode, n);
262 
263 		if (IS_ERR(page)) {
264 			EXOFS_ERR("ERROR: bad page in directory(0x%lx)\n",
265 				  inode->i_ino);
266 			filp->f_pos += PAGE_CACHE_SIZE - offset;
267 			return PTR_ERR(page);
268 		}
269 		kaddr = page_address(page);
270 		if (unlikely(need_revalidate)) {
271 			if (offset) {
272 				offset = exofs_validate_entry(kaddr, offset,
273 								chunk_mask);
274 				filp->f_pos = (n<<PAGE_CACHE_SHIFT) + offset;
275 			}
276 			filp->f_version = inode->i_version;
277 			need_revalidate = 0;
278 		}
279 		de = (struct exofs_dir_entry *)(kaddr + offset);
280 		limit = kaddr + exofs_last_byte(inode, n) -
281 							EXOFS_DIR_REC_LEN(1);
282 		for (; (char *)de <= limit; de = exofs_next_entry(de)) {
283 			if (de->rec_len == 0) {
284 				EXOFS_ERR("ERROR: "
285 				     "zero-length entry in directory(0x%lx)\n",
286 				     inode->i_ino);
287 				exofs_put_page(page);
288 				return -EIO;
289 			}
290 			if (de->inode_no) {
291 				int over;
292 				unsigned char d_type = DT_UNKNOWN;
293 
294 				if (types && de->file_type < EXOFS_FT_MAX)
295 					d_type = types[de->file_type];
296 
297 				offset = (char *)de - kaddr;
298 				over = filldir(dirent, de->name, de->name_len,
299 						(n<<PAGE_CACHE_SHIFT) | offset,
300 						le64_to_cpu(de->inode_no),
301 						d_type);
302 				if (over) {
303 					exofs_put_page(page);
304 					return 0;
305 				}
306 			}
307 			filp->f_pos += le16_to_cpu(de->rec_len);
308 		}
309 		exofs_put_page(page);
310 	}
311 
312 	return 0;
313 }
314 
exofs_find_entry(struct inode * dir,struct dentry * dentry,struct page ** res_page)315 struct exofs_dir_entry *exofs_find_entry(struct inode *dir,
316 			struct dentry *dentry, struct page **res_page)
317 {
318 	const unsigned char *name = dentry->d_name.name;
319 	int namelen = dentry->d_name.len;
320 	unsigned reclen = EXOFS_DIR_REC_LEN(namelen);
321 	unsigned long start, n;
322 	unsigned long npages = dir_pages(dir);
323 	struct page *page = NULL;
324 	struct exofs_i_info *oi = exofs_i(dir);
325 	struct exofs_dir_entry *de;
326 
327 	if (npages == 0)
328 		goto out;
329 
330 	*res_page = NULL;
331 
332 	start = oi->i_dir_start_lookup;
333 	if (start >= npages)
334 		start = 0;
335 	n = start;
336 	do {
337 		char *kaddr;
338 		page = exofs_get_page(dir, n);
339 		if (!IS_ERR(page)) {
340 			kaddr = page_address(page);
341 			de = (struct exofs_dir_entry *) kaddr;
342 			kaddr += exofs_last_byte(dir, n) - reclen;
343 			while ((char *) de <= kaddr) {
344 				if (de->rec_len == 0) {
345 					EXOFS_ERR("ERROR: zero-length entry in "
346 						  "directory(0x%lx)\n",
347 						  dir->i_ino);
348 					exofs_put_page(page);
349 					goto out;
350 				}
351 				if (exofs_match(namelen, name, de))
352 					goto found;
353 				de = exofs_next_entry(de);
354 			}
355 			exofs_put_page(page);
356 		}
357 		if (++n >= npages)
358 			n = 0;
359 	} while (n != start);
360 out:
361 	return NULL;
362 
363 found:
364 	*res_page = page;
365 	oi->i_dir_start_lookup = n;
366 	return de;
367 }
368 
exofs_dotdot(struct inode * dir,struct page ** p)369 struct exofs_dir_entry *exofs_dotdot(struct inode *dir, struct page **p)
370 {
371 	struct page *page = exofs_get_page(dir, 0);
372 	struct exofs_dir_entry *de = NULL;
373 
374 	if (!IS_ERR(page)) {
375 		de = exofs_next_entry(
376 				(struct exofs_dir_entry *)page_address(page));
377 		*p = page;
378 	}
379 	return de;
380 }
381 
exofs_parent_ino(struct dentry * child)382 ino_t exofs_parent_ino(struct dentry *child)
383 {
384 	struct page *page;
385 	struct exofs_dir_entry *de;
386 	ino_t ino;
387 
388 	de = exofs_dotdot(child->d_inode, &page);
389 	if (!de)
390 		return 0;
391 
392 	ino = le64_to_cpu(de->inode_no);
393 	exofs_put_page(page);
394 	return ino;
395 }
396 
exofs_inode_by_name(struct inode * dir,struct dentry * dentry)397 ino_t exofs_inode_by_name(struct inode *dir, struct dentry *dentry)
398 {
399 	ino_t res = 0;
400 	struct exofs_dir_entry *de;
401 	struct page *page;
402 
403 	de = exofs_find_entry(dir, dentry, &page);
404 	if (de) {
405 		res = le64_to_cpu(de->inode_no);
406 		exofs_put_page(page);
407 	}
408 	return res;
409 }
410 
exofs_set_link(struct inode * dir,struct exofs_dir_entry * de,struct page * page,struct inode * inode)411 int exofs_set_link(struct inode *dir, struct exofs_dir_entry *de,
412 			struct page *page, struct inode *inode)
413 {
414 	loff_t pos = page_offset(page) +
415 			(char *) de - (char *) page_address(page);
416 	unsigned len = le16_to_cpu(de->rec_len);
417 	int err;
418 
419 	lock_page(page);
420 	err = exofs_write_begin(NULL, page->mapping, pos, len,
421 				AOP_FLAG_UNINTERRUPTIBLE, &page, NULL);
422 	if (err)
423 		EXOFS_ERR("exofs_set_link: exofs_write_begin FAILED => %d\n",
424 			  err);
425 
426 	de->inode_no = cpu_to_le64(inode->i_ino);
427 	exofs_set_de_type(de, inode);
428 	if (likely(!err))
429 		err = exofs_commit_chunk(page, pos, len);
430 	exofs_put_page(page);
431 	dir->i_mtime = dir->i_ctime = CURRENT_TIME;
432 	mark_inode_dirty(dir);
433 	return err;
434 }
435 
exofs_add_link(struct dentry * dentry,struct inode * inode)436 int exofs_add_link(struct dentry *dentry, struct inode *inode)
437 {
438 	struct inode *dir = dentry->d_parent->d_inode;
439 	const unsigned char *name = dentry->d_name.name;
440 	int namelen = dentry->d_name.len;
441 	unsigned chunk_size = exofs_chunk_size(dir);
442 	unsigned reclen = EXOFS_DIR_REC_LEN(namelen);
443 	unsigned short rec_len, name_len;
444 	struct page *page = NULL;
445 	struct exofs_sb_info *sbi = inode->i_sb->s_fs_info;
446 	struct exofs_dir_entry *de;
447 	unsigned long npages = dir_pages(dir);
448 	unsigned long n;
449 	char *kaddr;
450 	loff_t pos;
451 	int err;
452 
453 	for (n = 0; n <= npages; n++) {
454 		char *dir_end;
455 
456 		page = exofs_get_page(dir, n);
457 		err = PTR_ERR(page);
458 		if (IS_ERR(page))
459 			goto out;
460 		lock_page(page);
461 		kaddr = page_address(page);
462 		dir_end = kaddr + exofs_last_byte(dir, n);
463 		de = (struct exofs_dir_entry *)kaddr;
464 		kaddr += PAGE_CACHE_SIZE - reclen;
465 		while ((char *)de <= kaddr) {
466 			if ((char *)de == dir_end) {
467 				name_len = 0;
468 				rec_len = chunk_size;
469 				de->rec_len = cpu_to_le16(chunk_size);
470 				de->inode_no = 0;
471 				goto got_it;
472 			}
473 			if (de->rec_len == 0) {
474 				EXOFS_ERR("ERROR: exofs_add_link: "
475 				      "zero-length entry in directory(0x%lx)\n",
476 				      inode->i_ino);
477 				err = -EIO;
478 				goto out_unlock;
479 			}
480 			err = -EEXIST;
481 			if (exofs_match(namelen, name, de))
482 				goto out_unlock;
483 			name_len = EXOFS_DIR_REC_LEN(de->name_len);
484 			rec_len = le16_to_cpu(de->rec_len);
485 			if (!de->inode_no && rec_len >= reclen)
486 				goto got_it;
487 			if (rec_len >= name_len + reclen)
488 				goto got_it;
489 			de = (struct exofs_dir_entry *) ((char *) de + rec_len);
490 		}
491 		unlock_page(page);
492 		exofs_put_page(page);
493 	}
494 
495 	EXOFS_ERR("exofs_add_link: BAD dentry=%p or inode=0x%lx\n",
496 		  dentry, inode->i_ino);
497 	return -EINVAL;
498 
499 got_it:
500 	pos = page_offset(page) +
501 		(char *)de - (char *)page_address(page);
502 	err = exofs_write_begin(NULL, page->mapping, pos, rec_len, 0,
503 							&page, NULL);
504 	if (err)
505 		goto out_unlock;
506 	if (de->inode_no) {
507 		struct exofs_dir_entry *de1 =
508 			(struct exofs_dir_entry *)((char *)de + name_len);
509 		de1->rec_len = cpu_to_le16(rec_len - name_len);
510 		de->rec_len = cpu_to_le16(name_len);
511 		de = de1;
512 	}
513 	de->name_len = namelen;
514 	memcpy(de->name, name, namelen);
515 	de->inode_no = cpu_to_le64(inode->i_ino);
516 	exofs_set_de_type(de, inode);
517 	err = exofs_commit_chunk(page, pos, rec_len);
518 	dir->i_mtime = dir->i_ctime = CURRENT_TIME;
519 	mark_inode_dirty(dir);
520 	sbi->s_numfiles++;
521 
522 out_put:
523 	exofs_put_page(page);
524 out:
525 	return err;
526 out_unlock:
527 	unlock_page(page);
528 	goto out_put;
529 }
530 
exofs_delete_entry(struct exofs_dir_entry * dir,struct page * page)531 int exofs_delete_entry(struct exofs_dir_entry *dir, struct page *page)
532 {
533 	struct address_space *mapping = page->mapping;
534 	struct inode *inode = mapping->host;
535 	struct exofs_sb_info *sbi = inode->i_sb->s_fs_info;
536 	char *kaddr = page_address(page);
537 	unsigned from = ((char *)dir - kaddr) & ~(exofs_chunk_size(inode)-1);
538 	unsigned to = ((char *)dir - kaddr) + le16_to_cpu(dir->rec_len);
539 	loff_t pos;
540 	struct exofs_dir_entry *pde = NULL;
541 	struct exofs_dir_entry *de = (struct exofs_dir_entry *) (kaddr + from);
542 	int err;
543 
544 	while (de < dir) {
545 		if (de->rec_len == 0) {
546 			EXOFS_ERR("ERROR: exofs_delete_entry:"
547 				  "zero-length entry in directory(0x%lx)\n",
548 				  inode->i_ino);
549 			err = -EIO;
550 			goto out;
551 		}
552 		pde = de;
553 		de = exofs_next_entry(de);
554 	}
555 	if (pde)
556 		from = (char *)pde - (char *)page_address(page);
557 	pos = page_offset(page) + from;
558 	lock_page(page);
559 	err = exofs_write_begin(NULL, page->mapping, pos, to - from, 0,
560 							&page, NULL);
561 	if (err)
562 		EXOFS_ERR("exofs_delete_entry: exofs_write_begin FAILED => %d\n",
563 			  err);
564 	if (pde)
565 		pde->rec_len = cpu_to_le16(to - from);
566 	dir->inode_no = 0;
567 	if (likely(!err))
568 		err = exofs_commit_chunk(page, pos, to - from);
569 	inode->i_ctime = inode->i_mtime = CURRENT_TIME;
570 	mark_inode_dirty(inode);
571 	sbi->s_numfiles--;
572 out:
573 	exofs_put_page(page);
574 	return err;
575 }
576 
577 /* kept aligned on 4 bytes */
578 #define THIS_DIR ".\0\0"
579 #define PARENT_DIR "..\0"
580 
exofs_make_empty(struct inode * inode,struct inode * parent)581 int exofs_make_empty(struct inode *inode, struct inode *parent)
582 {
583 	struct address_space *mapping = inode->i_mapping;
584 	struct page *page = grab_cache_page(mapping, 0);
585 	unsigned chunk_size = exofs_chunk_size(inode);
586 	struct exofs_dir_entry *de;
587 	int err;
588 	void *kaddr;
589 
590 	if (!page)
591 		return -ENOMEM;
592 
593 	err = exofs_write_begin(NULL, page->mapping, 0, chunk_size, 0,
594 							&page, NULL);
595 	if (err) {
596 		unlock_page(page);
597 		goto fail;
598 	}
599 
600 	kaddr = kmap_atomic(page);
601 	de = (struct exofs_dir_entry *)kaddr;
602 	de->name_len = 1;
603 	de->rec_len = cpu_to_le16(EXOFS_DIR_REC_LEN(1));
604 	memcpy(de->name, THIS_DIR, sizeof(THIS_DIR));
605 	de->inode_no = cpu_to_le64(inode->i_ino);
606 	exofs_set_de_type(de, inode);
607 
608 	de = (struct exofs_dir_entry *)(kaddr + EXOFS_DIR_REC_LEN(1));
609 	de->name_len = 2;
610 	de->rec_len = cpu_to_le16(chunk_size - EXOFS_DIR_REC_LEN(1));
611 	de->inode_no = cpu_to_le64(parent->i_ino);
612 	memcpy(de->name, PARENT_DIR, sizeof(PARENT_DIR));
613 	exofs_set_de_type(de, inode);
614 	kunmap_atomic(kaddr);
615 	err = exofs_commit_chunk(page, 0, chunk_size);
616 fail:
617 	page_cache_release(page);
618 	return err;
619 }
620 
exofs_empty_dir(struct inode * inode)621 int exofs_empty_dir(struct inode *inode)
622 {
623 	struct page *page = NULL;
624 	unsigned long i, npages = dir_pages(inode);
625 
626 	for (i = 0; i < npages; i++) {
627 		char *kaddr;
628 		struct exofs_dir_entry *de;
629 		page = exofs_get_page(inode, i);
630 
631 		if (IS_ERR(page))
632 			continue;
633 
634 		kaddr = page_address(page);
635 		de = (struct exofs_dir_entry *)kaddr;
636 		kaddr += exofs_last_byte(inode, i) - EXOFS_DIR_REC_LEN(1);
637 
638 		while ((char *)de <= kaddr) {
639 			if (de->rec_len == 0) {
640 				EXOFS_ERR("ERROR: exofs_empty_dir: "
641 					  "zero-length directory entry"
642 					  "kaddr=%p, de=%p\n", kaddr, de);
643 				goto not_empty;
644 			}
645 			if (de->inode_no != 0) {
646 				/* check for . and .. */
647 				if (de->name[0] != '.')
648 					goto not_empty;
649 				if (de->name_len > 2)
650 					goto not_empty;
651 				if (de->name_len < 2) {
652 					if (le64_to_cpu(de->inode_no) !=
653 					    inode->i_ino)
654 						goto not_empty;
655 				} else if (de->name[1] != '.')
656 					goto not_empty;
657 			}
658 			de = exofs_next_entry(de);
659 		}
660 		exofs_put_page(page);
661 	}
662 	return 1;
663 
664 not_empty:
665 	exofs_put_page(page);
666 	return 0;
667 }
668 
669 const struct file_operations exofs_dir_operations = {
670 	.llseek		= generic_file_llseek,
671 	.read		= generic_read_dir,
672 	.readdir	= exofs_readdir,
673 };
674