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 */
ext2_rec_len_from_disk(__le16 dlen)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
ext2_rec_len_to_disk(unsigned len)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 */
ext2_chunk_size(struct inode * inode)64 static inline unsigned ext2_chunk_size(struct inode *inode)
65 {
66 return inode->i_sb->s_blocksize;
67 }
68
ext2_put_page(struct page * page)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
ext2_last_byte(struct inode * inode,unsigned long page_nr)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
ext2_commit_chunk(struct page * page,loff_t pos,unsigned len)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
ext2_check_page(struct page * page,int quiet)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
ext2_get_page(struct inode * dir,unsigned long n,int quiet)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 */
ext2_match(int len,const char * const name,struct ext2_dir_entry_2 * de)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 */
ext2_next_entry(ext2_dirent * p)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
ext2_validate_entry(char * base,unsigned offset,unsigned mask)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
ext2_set_de_type(ext2_dirent * de,struct inode * inode)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
ext2_readdir(struct file * file,struct dir_context * ctx)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 */
ext2_find_entry(struct inode * dir,const struct qstr * child,struct page ** res_page)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
ext2_dotdot(struct inode * dir,struct page ** p)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
ext2_inode_by_name(struct inode * dir,const struct qstr * child)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
ext2_prepare_chunk(struct page * page,loff_t pos,unsigned len)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 */
ext2_set_link(struct inode * dir,struct ext2_dir_entry_2 * de,struct page * page,struct inode * inode,int update_times)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 */
ext2_add_link(struct dentry * dentry,struct inode * inode)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 */
ext2_delete_entry(struct ext2_dir_entry_2 * dir,struct page * page)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 */
ext2_make_empty(struct inode * inode,struct inode * parent)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 */
ext2_empty_dir(struct inode * inode)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