1 /*
2 * linux/fs/ext2/dir.c
3 *
4 * Copyright (C) 1992, 1993, 1994, 1995
5 * Remy Card (card@masi.ibp.fr)
6 * Laboratoire MASI - Institut Blaise Pascal
7 * Universite Pierre et Marie Curie (Paris VI)
8 *
9 * from
10 *
11 * linux/fs/minix/dir.c
12 *
13 * Copyright (C) 1991, 1992 Linus Torvalds
14 *
15 * ext2 directory handling functions
16 *
17 * Big-endian to little-endian byte-swapping/bitmaps by
18 * David S. Miller (davem@caip.rutgers.edu), 1995
19 *
20 * All code that works with directory layout had been switched to pagecache
21 * and moved here. AV
22 */
23
24 #include "ext2.h"
25 #include <linux/buffer_head.h>
26 #include <linux/pagemap.h>
27 #include <linux/swap.h>
28
29 typedef struct ext2_dir_entry_2 ext2_dirent;
30
31 /*
32 * Tests against MAX_REC_LEN etc were put in place for 64k block
33 * sizes; if that is not possible on this arch, we can skip
34 * those tests and speed things up.
35 */
ext2_rec_len_from_disk(__le16 dlen)36 static inline unsigned ext2_rec_len_from_disk(__le16 dlen)
37 {
38 unsigned len = le16_to_cpu(dlen);
39
40 #if (PAGE_SIZE >= 65536)
41 if (len == EXT2_MAX_REC_LEN)
42 return 1 << 16;
43 #endif
44 return len;
45 }
46
ext2_rec_len_to_disk(unsigned len)47 static inline __le16 ext2_rec_len_to_disk(unsigned len)
48 {
49 #if (PAGE_SIZE >= 65536)
50 if (len == (1 << 16))
51 return cpu_to_le16(EXT2_MAX_REC_LEN);
52 else
53 BUG_ON(len > (1 << 16));
54 #endif
55 return cpu_to_le16(len);
56 }
57
58 /*
59 * ext2 uses block-sized chunks. Arguably, sector-sized ones would be
60 * more robust, but we have what we have
61 */
ext2_chunk_size(struct inode * inode)62 static inline unsigned ext2_chunk_size(struct inode *inode)
63 {
64 return inode->i_sb->s_blocksize;
65 }
66
ext2_put_page(struct page * page)67 static inline void ext2_put_page(struct page *page)
68 {
69 kunmap(page);
70 put_page(page);
71 }
72
73 /*
74 * Return the offset into page `page_nr' of the last valid
75 * byte in that page, plus one.
76 */
77 static unsigned
ext2_last_byte(struct inode * inode,unsigned long page_nr)78 ext2_last_byte(struct inode *inode, unsigned long page_nr)
79 {
80 unsigned last_byte = inode->i_size;
81
82 last_byte -= page_nr << PAGE_SHIFT;
83 if (last_byte > PAGE_SIZE)
84 last_byte = PAGE_SIZE;
85 return last_byte;
86 }
87
ext2_commit_chunk(struct page * page,loff_t pos,unsigned len)88 static int ext2_commit_chunk(struct page *page, loff_t pos, unsigned len)
89 {
90 struct address_space *mapping = page->mapping;
91 struct inode *dir = mapping->host;
92 int err = 0;
93
94 dir->i_version++;
95 block_write_end(NULL, mapping, pos, len, len, page, NULL);
96
97 if (pos+len > dir->i_size) {
98 i_size_write(dir, pos+len);
99 mark_inode_dirty(dir);
100 }
101
102 if (IS_DIRSYNC(dir)) {
103 err = write_one_page(page, 1);
104 if (!err)
105 err = sync_inode_metadata(dir, 1);
106 } else {
107 unlock_page(page);
108 }
109
110 return err;
111 }
112
ext2_check_page(struct page * page,int quiet)113 static bool ext2_check_page(struct page *page, int quiet)
114 {
115 struct inode *dir = page->mapping->host;
116 struct super_block *sb = dir->i_sb;
117 unsigned chunk_size = ext2_chunk_size(dir);
118 char *kaddr = page_address(page);
119 u32 max_inumber = le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count);
120 unsigned offs, rec_len;
121 unsigned limit = PAGE_SIZE;
122 ext2_dirent *p;
123 char *error;
124
125 if ((dir->i_size >> PAGE_SHIFT) == page->index) {
126 limit = dir->i_size & ~PAGE_MASK;
127 if (limit & (chunk_size - 1))
128 goto Ebadsize;
129 if (!limit)
130 goto out;
131 }
132 for (offs = 0; offs <= limit - EXT2_DIR_REC_LEN(1); offs += rec_len) {
133 p = (ext2_dirent *)(kaddr + offs);
134 rec_len = ext2_rec_len_from_disk(p->rec_len);
135
136 if (unlikely(rec_len < EXT2_DIR_REC_LEN(1)))
137 goto Eshort;
138 if (unlikely(rec_len & 3))
139 goto Ealign;
140 if (unlikely(rec_len < EXT2_DIR_REC_LEN(p->name_len)))
141 goto Enamelen;
142 if (unlikely(((offs + rec_len - 1) ^ offs) & ~(chunk_size-1)))
143 goto Espan;
144 if (unlikely(le32_to_cpu(p->inode) > max_inumber))
145 goto Einumber;
146 }
147 if (offs != limit)
148 goto Eend;
149 out:
150 SetPageChecked(page);
151 return true;
152
153 /* Too bad, we had an error */
154
155 Ebadsize:
156 if (!quiet)
157 ext2_error(sb, __func__,
158 "size of directory #%lu is not a multiple "
159 "of chunk size", dir->i_ino);
160 goto fail;
161 Eshort:
162 error = "rec_len is smaller than minimal";
163 goto bad_entry;
164 Ealign:
165 error = "unaligned directory entry";
166 goto bad_entry;
167 Enamelen:
168 error = "rec_len is too small for name_len";
169 goto bad_entry;
170 Espan:
171 error = "directory entry across blocks";
172 goto bad_entry;
173 Einumber:
174 error = "inode out of bounds";
175 bad_entry:
176 if (!quiet)
177 ext2_error(sb, __func__, "bad entry in directory #%lu: : %s - "
178 "offset=%lu, inode=%lu, rec_len=%d, name_len=%d",
179 dir->i_ino, error, (page->index<<PAGE_SHIFT)+offs,
180 (unsigned long) le32_to_cpu(p->inode),
181 rec_len, p->name_len);
182 goto fail;
183 Eend:
184 if (!quiet) {
185 p = (ext2_dirent *)(kaddr + offs);
186 ext2_error(sb, "ext2_check_page",
187 "entry in directory #%lu spans the page boundary"
188 "offset=%lu, inode=%lu",
189 dir->i_ino, (page->index<<PAGE_SHIFT)+offs,
190 (unsigned long) le32_to_cpu(p->inode));
191 }
192 fail:
193 SetPageError(page);
194 return false;
195 }
196
ext2_get_page(struct inode * dir,unsigned long n,int quiet)197 static struct page * ext2_get_page(struct inode *dir, unsigned long n,
198 int quiet)
199 {
200 struct address_space *mapping = dir->i_mapping;
201 struct page *page = read_mapping_page(mapping, n, NULL);
202 if (!IS_ERR(page)) {
203 kmap(page);
204 if (unlikely(!PageChecked(page))) {
205 if (PageError(page) || !ext2_check_page(page, quiet))
206 goto fail;
207 }
208 }
209 return page;
210
211 fail:
212 ext2_put_page(page);
213 return ERR_PTR(-EIO);
214 }
215
216 /*
217 * NOTE! unlike strncmp, ext2_match returns 1 for success, 0 for failure.
218 *
219 * len <= EXT2_NAME_LEN and de != NULL are guaranteed by caller.
220 */
ext2_match(int len,const char * const name,struct ext2_dir_entry_2 * de)221 static inline int ext2_match (int len, const char * const name,
222 struct ext2_dir_entry_2 * de)
223 {
224 if (len != de->name_len)
225 return 0;
226 if (!de->inode)
227 return 0;
228 return !memcmp(name, de->name, len);
229 }
230
231 /*
232 * p is at least 6 bytes before the end of page
233 */
ext2_next_entry(ext2_dirent * p)234 static inline ext2_dirent *ext2_next_entry(ext2_dirent *p)
235 {
236 return (ext2_dirent *)((char *)p +
237 ext2_rec_len_from_disk(p->rec_len));
238 }
239
240 static inline unsigned
ext2_validate_entry(char * base,unsigned offset,unsigned mask)241 ext2_validate_entry(char *base, unsigned offset, unsigned mask)
242 {
243 ext2_dirent *de = (ext2_dirent*)(base + offset);
244 ext2_dirent *p = (ext2_dirent*)(base + (offset&mask));
245 while ((char*)p < (char*)de) {
246 if (p->rec_len == 0)
247 break;
248 p = ext2_next_entry(p);
249 }
250 return (char *)p - base;
251 }
252
253 static unsigned char ext2_filetype_table[EXT2_FT_MAX] = {
254 [EXT2_FT_UNKNOWN] = DT_UNKNOWN,
255 [EXT2_FT_REG_FILE] = DT_REG,
256 [EXT2_FT_DIR] = DT_DIR,
257 [EXT2_FT_CHRDEV] = DT_CHR,
258 [EXT2_FT_BLKDEV] = DT_BLK,
259 [EXT2_FT_FIFO] = DT_FIFO,
260 [EXT2_FT_SOCK] = DT_SOCK,
261 [EXT2_FT_SYMLINK] = DT_LNK,
262 };
263
264 #define S_SHIFT 12
265 static unsigned char ext2_type_by_mode[S_IFMT >> S_SHIFT] = {
266 [S_IFREG >> S_SHIFT] = EXT2_FT_REG_FILE,
267 [S_IFDIR >> S_SHIFT] = EXT2_FT_DIR,
268 [S_IFCHR >> S_SHIFT] = EXT2_FT_CHRDEV,
269 [S_IFBLK >> S_SHIFT] = EXT2_FT_BLKDEV,
270 [S_IFIFO >> S_SHIFT] = EXT2_FT_FIFO,
271 [S_IFSOCK >> S_SHIFT] = EXT2_FT_SOCK,
272 [S_IFLNK >> S_SHIFT] = EXT2_FT_SYMLINK,
273 };
274
ext2_set_de_type(ext2_dirent * de,struct inode * inode)275 static inline void ext2_set_de_type(ext2_dirent *de, struct inode *inode)
276 {
277 umode_t mode = inode->i_mode;
278 if (EXT2_HAS_INCOMPAT_FEATURE(inode->i_sb, EXT2_FEATURE_INCOMPAT_FILETYPE))
279 de->file_type = ext2_type_by_mode[(mode & S_IFMT)>>S_SHIFT];
280 else
281 de->file_type = 0;
282 }
283
284 static int
ext2_readdir(struct file * file,struct dir_context * ctx)285 ext2_readdir(struct file *file, struct dir_context *ctx)
286 {
287 loff_t pos = ctx->pos;
288 struct inode *inode = file_inode(file);
289 struct super_block *sb = inode->i_sb;
290 unsigned int offset = pos & ~PAGE_MASK;
291 unsigned long n = pos >> PAGE_SHIFT;
292 unsigned long npages = dir_pages(inode);
293 unsigned chunk_mask = ~(ext2_chunk_size(inode)-1);
294 unsigned char *types = NULL;
295 int need_revalidate = file->f_version != inode->i_version;
296
297 if (pos > inode->i_size - EXT2_DIR_REC_LEN(1))
298 return 0;
299
300 if (EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_FILETYPE))
301 types = ext2_filetype_table;
302
303 for ( ; n < npages; n++, offset = 0) {
304 char *kaddr, *limit;
305 ext2_dirent *de;
306 struct page *page = ext2_get_page(inode, n, 0);
307
308 if (IS_ERR(page)) {
309 ext2_error(sb, __func__,
310 "bad page in #%lu",
311 inode->i_ino);
312 ctx->pos += PAGE_SIZE - offset;
313 return PTR_ERR(page);
314 }
315 kaddr = page_address(page);
316 if (unlikely(need_revalidate)) {
317 if (offset) {
318 offset = ext2_validate_entry(kaddr, offset, chunk_mask);
319 ctx->pos = (n<<PAGE_SHIFT) + offset;
320 }
321 file->f_version = inode->i_version;
322 need_revalidate = 0;
323 }
324 de = (ext2_dirent *)(kaddr+offset);
325 limit = kaddr + ext2_last_byte(inode, n) - EXT2_DIR_REC_LEN(1);
326 for ( ;(char*)de <= limit; de = ext2_next_entry(de)) {
327 if (de->rec_len == 0) {
328 ext2_error(sb, __func__,
329 "zero-length directory entry");
330 ext2_put_page(page);
331 return -EIO;
332 }
333 if (de->inode) {
334 unsigned char d_type = DT_UNKNOWN;
335
336 if (types && de->file_type < EXT2_FT_MAX)
337 d_type = types[de->file_type];
338
339 if (!dir_emit(ctx, de->name, de->name_len,
340 le32_to_cpu(de->inode),
341 d_type)) {
342 ext2_put_page(page);
343 return 0;
344 }
345 }
346 ctx->pos += ext2_rec_len_from_disk(de->rec_len);
347 }
348 ext2_put_page(page);
349 }
350 return 0;
351 }
352
353 /*
354 * ext2_find_entry()
355 *
356 * finds an entry in the specified directory with the wanted name. It
357 * returns the page in which the entry was found (as a parameter - res_page),
358 * and the entry itself. Page is returned mapped and unlocked.
359 * Entry is guaranteed to be valid.
360 */
ext2_find_entry(struct inode * dir,const struct qstr * child,struct page ** res_page)361 struct ext2_dir_entry_2 *ext2_find_entry (struct inode *dir,
362 const struct qstr *child, struct page **res_page)
363 {
364 const char *name = child->name;
365 int namelen = child->len;
366 unsigned reclen = EXT2_DIR_REC_LEN(namelen);
367 unsigned long start, n;
368 unsigned long npages = dir_pages(dir);
369 struct page *page = NULL;
370 struct ext2_inode_info *ei = EXT2_I(dir);
371 ext2_dirent * de;
372 int dir_has_error = 0;
373
374 if (npages == 0)
375 goto out;
376
377 /* OFFSET_CACHE */
378 *res_page = NULL;
379
380 start = ei->i_dir_start_lookup;
381 if (start >= npages)
382 start = 0;
383 n = start;
384 do {
385 char *kaddr;
386 page = ext2_get_page(dir, n, dir_has_error);
387 if (!IS_ERR(page)) {
388 kaddr = page_address(page);
389 de = (ext2_dirent *) kaddr;
390 kaddr += ext2_last_byte(dir, n) - reclen;
391 while ((char *) de <= kaddr) {
392 if (de->rec_len == 0) {
393 ext2_error(dir->i_sb, __func__,
394 "zero-length directory entry");
395 ext2_put_page(page);
396 goto out;
397 }
398 if (ext2_match (namelen, name, de))
399 goto found;
400 de = ext2_next_entry(de);
401 }
402 ext2_put_page(page);
403 } else
404 dir_has_error = 1;
405
406 if (++n >= npages)
407 n = 0;
408 /* next page is past the blocks we've got */
409 if (unlikely(n > (dir->i_blocks >> (PAGE_SHIFT - 9)))) {
410 ext2_error(dir->i_sb, __func__,
411 "dir %lu size %lld exceeds block count %llu",
412 dir->i_ino, dir->i_size,
413 (unsigned long long)dir->i_blocks);
414 goto out;
415 }
416 } while (n != start);
417 out:
418 return NULL;
419
420 found:
421 *res_page = page;
422 ei->i_dir_start_lookup = n;
423 return de;
424 }
425
ext2_dotdot(struct inode * dir,struct page ** p)426 struct ext2_dir_entry_2 * ext2_dotdot (struct inode *dir, struct page **p)
427 {
428 struct page *page = ext2_get_page(dir, 0, 0);
429 ext2_dirent *de = NULL;
430
431 if (!IS_ERR(page)) {
432 de = ext2_next_entry((ext2_dirent *) page_address(page));
433 *p = page;
434 }
435 return de;
436 }
437
ext2_inode_by_name(struct inode * dir,const struct qstr * child)438 ino_t ext2_inode_by_name(struct inode *dir, const struct qstr *child)
439 {
440 ino_t res = 0;
441 struct ext2_dir_entry_2 *de;
442 struct page *page;
443
444 de = ext2_find_entry (dir, child, &page);
445 if (de) {
446 res = le32_to_cpu(de->inode);
447 ext2_put_page(page);
448 }
449 return res;
450 }
451
ext2_prepare_chunk(struct page * page,loff_t pos,unsigned len)452 static int ext2_prepare_chunk(struct page *page, loff_t pos, unsigned len)
453 {
454 return __block_write_begin(page, pos, len, ext2_get_block);
455 }
456
457 /* Releases the page */
ext2_set_link(struct inode * dir,struct ext2_dir_entry_2 * de,struct page * page,struct inode * inode,int update_times)458 void ext2_set_link(struct inode *dir, struct ext2_dir_entry_2 *de,
459 struct page *page, struct inode *inode, int update_times)
460 {
461 loff_t pos = page_offset(page) +
462 (char *) de - (char *) page_address(page);
463 unsigned len = ext2_rec_len_from_disk(de->rec_len);
464 int err;
465
466 lock_page(page);
467 err = ext2_prepare_chunk(page, pos, len);
468 BUG_ON(err);
469 de->inode = cpu_to_le32(inode->i_ino);
470 ext2_set_de_type(de, inode);
471 err = ext2_commit_chunk(page, pos, len);
472 ext2_put_page(page);
473 if (update_times)
474 dir->i_mtime = dir->i_ctime = current_time(dir);
475 EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL;
476 mark_inode_dirty(dir);
477 }
478
479 /*
480 * Parent is locked.
481 */
ext2_add_link(struct dentry * dentry,struct inode * inode)482 int ext2_add_link (struct dentry *dentry, struct inode *inode)
483 {
484 struct inode *dir = d_inode(dentry->d_parent);
485 const char *name = dentry->d_name.name;
486 int namelen = dentry->d_name.len;
487 unsigned chunk_size = ext2_chunk_size(dir);
488 unsigned reclen = EXT2_DIR_REC_LEN(namelen);
489 unsigned short rec_len, name_len;
490 struct page *page = NULL;
491 ext2_dirent * de;
492 unsigned long npages = dir_pages(dir);
493 unsigned long n;
494 char *kaddr;
495 loff_t pos;
496 int err;
497
498 /*
499 * We take care of directory expansion in the same loop.
500 * This code plays outside i_size, so it locks the page
501 * to protect that region.
502 */
503 for (n = 0; n <= npages; n++) {
504 char *dir_end;
505
506 page = ext2_get_page(dir, n, 0);
507 err = PTR_ERR(page);
508 if (IS_ERR(page))
509 goto out;
510 lock_page(page);
511 kaddr = page_address(page);
512 dir_end = kaddr + ext2_last_byte(dir, n);
513 de = (ext2_dirent *)kaddr;
514 kaddr += PAGE_SIZE - reclen;
515 while ((char *)de <= kaddr) {
516 if ((char *)de == dir_end) {
517 /* We hit i_size */
518 name_len = 0;
519 rec_len = chunk_size;
520 de->rec_len = ext2_rec_len_to_disk(chunk_size);
521 de->inode = 0;
522 goto got_it;
523 }
524 if (de->rec_len == 0) {
525 ext2_error(dir->i_sb, __func__,
526 "zero-length directory entry");
527 err = -EIO;
528 goto out_unlock;
529 }
530 err = -EEXIST;
531 if (ext2_match (namelen, name, de))
532 goto out_unlock;
533 name_len = EXT2_DIR_REC_LEN(de->name_len);
534 rec_len = ext2_rec_len_from_disk(de->rec_len);
535 if (!de->inode && rec_len >= reclen)
536 goto got_it;
537 if (rec_len >= name_len + reclen)
538 goto got_it;
539 de = (ext2_dirent *) ((char *) de + rec_len);
540 }
541 unlock_page(page);
542 ext2_put_page(page);
543 }
544 BUG();
545 return -EINVAL;
546
547 got_it:
548 pos = page_offset(page) +
549 (char*)de - (char*)page_address(page);
550 err = ext2_prepare_chunk(page, pos, rec_len);
551 if (err)
552 goto out_unlock;
553 if (de->inode) {
554 ext2_dirent *de1 = (ext2_dirent *) ((char *) de + name_len);
555 de1->rec_len = ext2_rec_len_to_disk(rec_len - name_len);
556 de->rec_len = ext2_rec_len_to_disk(name_len);
557 de = de1;
558 }
559 de->name_len = namelen;
560 memcpy(de->name, name, namelen);
561 de->inode = cpu_to_le32(inode->i_ino);
562 ext2_set_de_type (de, inode);
563 err = ext2_commit_chunk(page, pos, rec_len);
564 dir->i_mtime = dir->i_ctime = current_time(dir);
565 EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL;
566 mark_inode_dirty(dir);
567 /* OFFSET_CACHE */
568 out_put:
569 ext2_put_page(page);
570 out:
571 return err;
572 out_unlock:
573 unlock_page(page);
574 goto out_put;
575 }
576
577 /*
578 * ext2_delete_entry deletes a directory entry by merging it with the
579 * previous entry. Page is up-to-date. Releases the page.
580 */
ext2_delete_entry(struct ext2_dir_entry_2 * dir,struct page * page)581 int ext2_delete_entry (struct ext2_dir_entry_2 * dir, struct page * page )
582 {
583 struct inode *inode = page->mapping->host;
584 char *kaddr = page_address(page);
585 unsigned from = ((char*)dir - kaddr) & ~(ext2_chunk_size(inode)-1);
586 unsigned to = ((char *)dir - kaddr) +
587 ext2_rec_len_from_disk(dir->rec_len);
588 loff_t pos;
589 ext2_dirent * pde = NULL;
590 ext2_dirent * de = (ext2_dirent *) (kaddr + from);
591 int err;
592
593 while ((char*)de < (char*)dir) {
594 if (de->rec_len == 0) {
595 ext2_error(inode->i_sb, __func__,
596 "zero-length directory entry");
597 err = -EIO;
598 goto out;
599 }
600 pde = de;
601 de = ext2_next_entry(de);
602 }
603 if (pde)
604 from = (char*)pde - (char*)page_address(page);
605 pos = page_offset(page) + from;
606 lock_page(page);
607 err = ext2_prepare_chunk(page, pos, to - from);
608 BUG_ON(err);
609 if (pde)
610 pde->rec_len = ext2_rec_len_to_disk(to - from);
611 dir->inode = 0;
612 err = ext2_commit_chunk(page, pos, to - from);
613 inode->i_ctime = inode->i_mtime = current_time(inode);
614 EXT2_I(inode)->i_flags &= ~EXT2_BTREE_FL;
615 mark_inode_dirty(inode);
616 out:
617 ext2_put_page(page);
618 return err;
619 }
620
621 /*
622 * Set the first fragment of directory.
623 */
ext2_make_empty(struct inode * inode,struct inode * parent)624 int ext2_make_empty(struct inode *inode, struct inode *parent)
625 {
626 struct page *page = grab_cache_page(inode->i_mapping, 0);
627 unsigned chunk_size = ext2_chunk_size(inode);
628 struct ext2_dir_entry_2 * de;
629 int err;
630 void *kaddr;
631
632 if (!page)
633 return -ENOMEM;
634
635 err = ext2_prepare_chunk(page, 0, chunk_size);
636 if (err) {
637 unlock_page(page);
638 goto fail;
639 }
640 kaddr = kmap_atomic(page);
641 memset(kaddr, 0, chunk_size);
642 de = (struct ext2_dir_entry_2 *)kaddr;
643 de->name_len = 1;
644 de->rec_len = ext2_rec_len_to_disk(EXT2_DIR_REC_LEN(1));
645 memcpy (de->name, ".\0\0", 4);
646 de->inode = cpu_to_le32(inode->i_ino);
647 ext2_set_de_type (de, inode);
648
649 de = (struct ext2_dir_entry_2 *)(kaddr + EXT2_DIR_REC_LEN(1));
650 de->name_len = 2;
651 de->rec_len = ext2_rec_len_to_disk(chunk_size - EXT2_DIR_REC_LEN(1));
652 de->inode = cpu_to_le32(parent->i_ino);
653 memcpy (de->name, "..\0", 4);
654 ext2_set_de_type (de, inode);
655 kunmap_atomic(kaddr);
656 err = ext2_commit_chunk(page, 0, chunk_size);
657 fail:
658 put_page(page);
659 return err;
660 }
661
662 /*
663 * routine to check that the specified directory is empty (for rmdir)
664 */
ext2_empty_dir(struct inode * inode)665 int ext2_empty_dir (struct inode * inode)
666 {
667 struct page *page = NULL;
668 unsigned long i, npages = dir_pages(inode);
669 int dir_has_error = 0;
670
671 for (i = 0; i < npages; i++) {
672 char *kaddr;
673 ext2_dirent * de;
674 page = ext2_get_page(inode, i, dir_has_error);
675
676 if (IS_ERR(page)) {
677 dir_has_error = 1;
678 continue;
679 }
680
681 kaddr = page_address(page);
682 de = (ext2_dirent *)kaddr;
683 kaddr += ext2_last_byte(inode, i) - EXT2_DIR_REC_LEN(1);
684
685 while ((char *)de <= kaddr) {
686 if (de->rec_len == 0) {
687 ext2_error(inode->i_sb, __func__,
688 "zero-length directory entry");
689 printk("kaddr=%p, de=%p\n", kaddr, de);
690 goto not_empty;
691 }
692 if (de->inode != 0) {
693 /* check for . and .. */
694 if (de->name[0] != '.')
695 goto not_empty;
696 if (de->name_len > 2)
697 goto not_empty;
698 if (de->name_len < 2) {
699 if (de->inode !=
700 cpu_to_le32(inode->i_ino))
701 goto not_empty;
702 } else if (de->name[1] != '.')
703 goto not_empty;
704 }
705 de = ext2_next_entry(de);
706 }
707 ext2_put_page(page);
708 }
709 return 1;
710
711 not_empty:
712 ext2_put_page(page);
713 return 0;
714 }
715
716 const struct file_operations ext2_dir_operations = {
717 .llseek = generic_file_llseek,
718 .read = generic_read_dir,
719 .iterate_shared = ext2_readdir,
720 .unlocked_ioctl = ext2_ioctl,
721 #ifdef CONFIG_COMPAT
722 .compat_ioctl = ext2_compat_ioctl,
723 #endif
724 .fsync = ext2_fsync,
725 };
726