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
69 /*
70 * Return the offset into page `page_nr' of the last valid
71 * byte in that page, plus one.
72 */
73 static unsigned
ext2_last_byte(struct inode * inode,unsigned long page_nr)74 ext2_last_byte(struct inode *inode, unsigned long page_nr)
75 {
76 unsigned last_byte = inode->i_size;
77
78 last_byte -= page_nr << PAGE_SHIFT;
79 if (last_byte > PAGE_SIZE)
80 last_byte = PAGE_SIZE;
81 return last_byte;
82 }
83
ext2_commit_chunk(struct page * page,loff_t pos,unsigned len)84 static void ext2_commit_chunk(struct page *page, loff_t pos, unsigned len)
85 {
86 struct address_space *mapping = page->mapping;
87 struct inode *dir = mapping->host;
88
89 inode_inc_iversion(dir);
90 block_write_end(NULL, mapping, pos, len, len, page, NULL);
91
92 if (pos+len > dir->i_size) {
93 i_size_write(dir, pos+len);
94 mark_inode_dirty(dir);
95 }
96 unlock_page(page);
97 }
98
ext2_check_page(struct page * page,int quiet,char * kaddr)99 static bool ext2_check_page(struct page *page, int quiet, char *kaddr)
100 {
101 struct inode *dir = page->mapping->host;
102 struct super_block *sb = dir->i_sb;
103 unsigned chunk_size = ext2_chunk_size(dir);
104 u32 max_inumber = le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count);
105 unsigned offs, rec_len;
106 unsigned limit = PAGE_SIZE;
107 ext2_dirent *p;
108 char *error;
109
110 if ((dir->i_size >> PAGE_SHIFT) == page->index) {
111 limit = dir->i_size & ~PAGE_MASK;
112 if (limit & (chunk_size - 1))
113 goto Ebadsize;
114 if (!limit)
115 goto out;
116 }
117 for (offs = 0; offs <= limit - EXT2_DIR_REC_LEN(1); offs += rec_len) {
118 p = (ext2_dirent *)(kaddr + offs);
119 rec_len = ext2_rec_len_from_disk(p->rec_len);
120
121 if (unlikely(rec_len < EXT2_DIR_REC_LEN(1)))
122 goto Eshort;
123 if (unlikely(rec_len & 3))
124 goto Ealign;
125 if (unlikely(rec_len < EXT2_DIR_REC_LEN(p->name_len)))
126 goto Enamelen;
127 if (unlikely(((offs + rec_len - 1) ^ offs) & ~(chunk_size-1)))
128 goto Espan;
129 if (unlikely(le32_to_cpu(p->inode) > max_inumber))
130 goto Einumber;
131 }
132 if (offs != limit)
133 goto Eend;
134 out:
135 SetPageChecked(page);
136 return true;
137
138 /* Too bad, we had an error */
139
140 Ebadsize:
141 if (!quiet)
142 ext2_error(sb, __func__,
143 "size of directory #%lu is not a multiple "
144 "of chunk size", dir->i_ino);
145 goto fail;
146 Eshort:
147 error = "rec_len is smaller than minimal";
148 goto bad_entry;
149 Ealign:
150 error = "unaligned directory entry";
151 goto bad_entry;
152 Enamelen:
153 error = "rec_len is too small for name_len";
154 goto bad_entry;
155 Espan:
156 error = "directory entry across blocks";
157 goto bad_entry;
158 Einumber:
159 error = "inode out of bounds";
160 bad_entry:
161 if (!quiet)
162 ext2_error(sb, __func__, "bad entry in directory #%lu: : %s - "
163 "offset=%lu, inode=%lu, rec_len=%d, name_len=%d",
164 dir->i_ino, error, (page->index<<PAGE_SHIFT)+offs,
165 (unsigned long) le32_to_cpu(p->inode),
166 rec_len, p->name_len);
167 goto fail;
168 Eend:
169 if (!quiet) {
170 p = (ext2_dirent *)(kaddr + offs);
171 ext2_error(sb, "ext2_check_page",
172 "entry in directory #%lu spans the page boundary"
173 "offset=%lu, inode=%lu",
174 dir->i_ino, (page->index<<PAGE_SHIFT)+offs,
175 (unsigned long) le32_to_cpu(p->inode));
176 }
177 fail:
178 SetPageError(page);
179 return false;
180 }
181
182 /*
183 * Calls to ext2_get_page()/ext2_put_page() must be nested according to the
184 * rules documented in kmap_local_page()/kunmap_local().
185 *
186 * NOTE: ext2_find_entry() and ext2_dotdot() act as a call to ext2_get_page()
187 * and should be treated as a call to ext2_get_page() for nesting purposes.
188 */
ext2_get_page(struct inode * dir,unsigned long n,int quiet,struct page ** page)189 static void *ext2_get_page(struct inode *dir, unsigned long n,
190 int quiet, struct page **page)
191 {
192 struct address_space *mapping = dir->i_mapping;
193 struct folio *folio = read_mapping_folio(mapping, n, NULL);
194 void *page_addr;
195
196 if (IS_ERR(folio))
197 return ERR_CAST(folio);
198 page_addr = kmap_local_folio(folio, n & (folio_nr_pages(folio) - 1));
199 if (unlikely(!folio_test_checked(folio))) {
200 if (!ext2_check_page(&folio->page, quiet, page_addr))
201 goto fail;
202 }
203 *page = &folio->page;
204 return page_addr;
205
206 fail:
207 ext2_put_page(&folio->page, page_addr);
208 return ERR_PTR(-EIO);
209 }
210
211 /*
212 * NOTE! unlike strncmp, ext2_match returns 1 for success, 0 for failure.
213 *
214 * len <= EXT2_NAME_LEN and de != NULL are guaranteed by caller.
215 */
ext2_match(int len,const char * const name,struct ext2_dir_entry_2 * de)216 static inline int ext2_match (int len, const char * const name,
217 struct ext2_dir_entry_2 * de)
218 {
219 if (len != de->name_len)
220 return 0;
221 if (!de->inode)
222 return 0;
223 return !memcmp(name, de->name, len);
224 }
225
226 /*
227 * p is at least 6 bytes before the end of page
228 */
ext2_next_entry(ext2_dirent * p)229 static inline ext2_dirent *ext2_next_entry(ext2_dirent *p)
230 {
231 return (ext2_dirent *)((char *)p +
232 ext2_rec_len_from_disk(p->rec_len));
233 }
234
235 static inline unsigned
ext2_validate_entry(char * base,unsigned offset,unsigned mask)236 ext2_validate_entry(char *base, unsigned offset, unsigned mask)
237 {
238 ext2_dirent *de = (ext2_dirent*)(base + offset);
239 ext2_dirent *p = (ext2_dirent*)(base + (offset&mask));
240 while ((char*)p < (char*)de) {
241 if (p->rec_len == 0)
242 break;
243 p = ext2_next_entry(p);
244 }
245 return offset_in_page(p);
246 }
247
ext2_set_de_type(ext2_dirent * de,struct inode * inode)248 static inline void ext2_set_de_type(ext2_dirent *de, struct inode *inode)
249 {
250 if (EXT2_HAS_INCOMPAT_FEATURE(inode->i_sb, EXT2_FEATURE_INCOMPAT_FILETYPE))
251 de->file_type = fs_umode_to_ftype(inode->i_mode);
252 else
253 de->file_type = 0;
254 }
255
256 static int
ext2_readdir(struct file * file,struct dir_context * ctx)257 ext2_readdir(struct file *file, struct dir_context *ctx)
258 {
259 loff_t pos = ctx->pos;
260 struct inode *inode = file_inode(file);
261 struct super_block *sb = inode->i_sb;
262 unsigned int offset = pos & ~PAGE_MASK;
263 unsigned long n = pos >> PAGE_SHIFT;
264 unsigned long npages = dir_pages(inode);
265 unsigned chunk_mask = ~(ext2_chunk_size(inode)-1);
266 bool need_revalidate = !inode_eq_iversion(inode, file->f_version);
267 bool has_filetype;
268
269 if (pos > inode->i_size - EXT2_DIR_REC_LEN(1))
270 return 0;
271
272 has_filetype =
273 EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_FILETYPE);
274
275 for ( ; n < npages; n++, offset = 0) {
276 ext2_dirent *de;
277 struct page *page;
278 char *kaddr = ext2_get_page(inode, n, 0, &page);
279 char *limit;
280
281 if (IS_ERR(kaddr)) {
282 ext2_error(sb, __func__,
283 "bad page in #%lu",
284 inode->i_ino);
285 ctx->pos += PAGE_SIZE - offset;
286 return PTR_ERR(kaddr);
287 }
288 if (unlikely(need_revalidate)) {
289 if (offset) {
290 offset = ext2_validate_entry(kaddr, offset, chunk_mask);
291 ctx->pos = (n<<PAGE_SHIFT) + offset;
292 }
293 file->f_version = inode_query_iversion(inode);
294 need_revalidate = false;
295 }
296 de = (ext2_dirent *)(kaddr+offset);
297 limit = kaddr + ext2_last_byte(inode, n) - EXT2_DIR_REC_LEN(1);
298 for ( ;(char*)de <= limit; de = ext2_next_entry(de)) {
299 if (de->rec_len == 0) {
300 ext2_error(sb, __func__,
301 "zero-length directory entry");
302 ext2_put_page(page, de);
303 return -EIO;
304 }
305 if (de->inode) {
306 unsigned char d_type = DT_UNKNOWN;
307
308 if (has_filetype)
309 d_type = fs_ftype_to_dtype(de->file_type);
310
311 if (!dir_emit(ctx, de->name, de->name_len,
312 le32_to_cpu(de->inode),
313 d_type)) {
314 ext2_put_page(page, de);
315 return 0;
316 }
317 }
318 ctx->pos += ext2_rec_len_from_disk(de->rec_len);
319 }
320 ext2_put_page(page, kaddr);
321 }
322 return 0;
323 }
324
325 /*
326 * ext2_find_entry()
327 *
328 * finds an entry in the specified directory with the wanted name. It
329 * returns the page in which the entry was found (as a parameter - res_page),
330 * and the entry itself. Page is returned mapped and unlocked.
331 * Entry is guaranteed to be valid.
332 *
333 * On Success ext2_put_page() should be called on *res_page.
334 *
335 * NOTE: Calls to ext2_get_page()/ext2_put_page() must be nested according to
336 * the rules documented in kmap_local_page()/kunmap_local().
337 *
338 * ext2_find_entry() and ext2_dotdot() act as a call to ext2_get_page() and
339 * should be treated as a call to ext2_get_page() for nesting purposes.
340 */
ext2_find_entry(struct inode * dir,const struct qstr * child,struct page ** res_page)341 struct ext2_dir_entry_2 *ext2_find_entry (struct inode *dir,
342 const struct qstr *child, struct page **res_page)
343 {
344 const char *name = child->name;
345 int namelen = child->len;
346 unsigned reclen = EXT2_DIR_REC_LEN(namelen);
347 unsigned long start, n;
348 unsigned long npages = dir_pages(dir);
349 struct page *page = NULL;
350 struct ext2_inode_info *ei = EXT2_I(dir);
351 ext2_dirent * de;
352
353 if (npages == 0)
354 goto out;
355
356 /* OFFSET_CACHE */
357 *res_page = NULL;
358
359 start = ei->i_dir_start_lookup;
360 if (start >= npages)
361 start = 0;
362 n = start;
363 do {
364 char *kaddr = ext2_get_page(dir, n, 0, &page);
365 if (IS_ERR(kaddr))
366 return ERR_CAST(kaddr);
367
368 de = (ext2_dirent *) kaddr;
369 kaddr += ext2_last_byte(dir, n) - reclen;
370 while ((char *) de <= kaddr) {
371 if (de->rec_len == 0) {
372 ext2_error(dir->i_sb, __func__,
373 "zero-length directory entry");
374 ext2_put_page(page, de);
375 goto out;
376 }
377 if (ext2_match(namelen, name, de))
378 goto found;
379 de = ext2_next_entry(de);
380 }
381 ext2_put_page(page, kaddr);
382
383 if (++n >= npages)
384 n = 0;
385 /* next page is past the blocks we've got */
386 if (unlikely(n > (dir->i_blocks >> (PAGE_SHIFT - 9)))) {
387 ext2_error(dir->i_sb, __func__,
388 "dir %lu size %lld exceeds block count %llu",
389 dir->i_ino, dir->i_size,
390 (unsigned long long)dir->i_blocks);
391 goto out;
392 }
393 } while (n != start);
394 out:
395 return ERR_PTR(-ENOENT);
396
397 found:
398 *res_page = page;
399 ei->i_dir_start_lookup = n;
400 return de;
401 }
402
403 /*
404 * Return the '..' directory entry and the page in which the entry was found
405 * (as a parameter - p).
406 *
407 * On Success ext2_put_page() should be called on *p.
408 *
409 * NOTE: Calls to ext2_get_page()/ext2_put_page() must be nested according to
410 * the rules documented in kmap_local_page()/kunmap_local().
411 *
412 * ext2_find_entry() and ext2_dotdot() act as a call to ext2_get_page() and
413 * should be treated as a call to ext2_get_page() for nesting purposes.
414 */
ext2_dotdot(struct inode * dir,struct page ** p)415 struct ext2_dir_entry_2 *ext2_dotdot(struct inode *dir, struct page **p)
416 {
417 ext2_dirent *de = ext2_get_page(dir, 0, 0, p);
418
419 if (!IS_ERR(de))
420 return ext2_next_entry(de);
421 return NULL;
422 }
423
ext2_inode_by_name(struct inode * dir,const struct qstr * child,ino_t * ino)424 int ext2_inode_by_name(struct inode *dir, const struct qstr *child, ino_t *ino)
425 {
426 struct ext2_dir_entry_2 *de;
427 struct page *page;
428
429 de = ext2_find_entry(dir, child, &page);
430 if (IS_ERR(de))
431 return PTR_ERR(de);
432
433 *ino = le32_to_cpu(de->inode);
434 ext2_put_page(page, de);
435 return 0;
436 }
437
ext2_prepare_chunk(struct page * page,loff_t pos,unsigned len)438 static int ext2_prepare_chunk(struct page *page, loff_t pos, unsigned len)
439 {
440 return __block_write_begin(page, pos, len, ext2_get_block);
441 }
442
443
ext2_handle_dirsync(struct inode * dir)444 static int ext2_handle_dirsync(struct inode *dir)
445 {
446 int err;
447
448 err = filemap_write_and_wait(dir->i_mapping);
449 if (!err)
450 err = sync_inode_metadata(dir, 1);
451 return err;
452 }
453
ext2_set_link(struct inode * dir,struct ext2_dir_entry_2 * de,struct page * page,struct inode * inode,bool update_times)454 int ext2_set_link(struct inode *dir, struct ext2_dir_entry_2 *de,
455 struct page *page, struct inode *inode, bool update_times)
456 {
457 loff_t pos = page_offset(page) + offset_in_page(de);
458 unsigned len = ext2_rec_len_from_disk(de->rec_len);
459 int err;
460
461 lock_page(page);
462 err = ext2_prepare_chunk(page, pos, len);
463 if (err) {
464 unlock_page(page);
465 return err;
466 }
467 de->inode = cpu_to_le32(inode->i_ino);
468 ext2_set_de_type(de, inode);
469 ext2_commit_chunk(page, pos, len);
470 if (update_times)
471 dir->i_mtime = inode_set_ctime_current(dir);
472 EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL;
473 mark_inode_dirty(dir);
474 return ext2_handle_dirsync(dir);
475 }
476
477 /*
478 * Parent is locked.
479 */
ext2_add_link(struct dentry * dentry,struct inode * inode)480 int ext2_add_link (struct dentry *dentry, struct inode *inode)
481 {
482 struct inode *dir = d_inode(dentry->d_parent);
483 const char *name = dentry->d_name.name;
484 int namelen = dentry->d_name.len;
485 unsigned chunk_size = ext2_chunk_size(dir);
486 unsigned reclen = EXT2_DIR_REC_LEN(namelen);
487 unsigned short rec_len, name_len;
488 struct page *page = NULL;
489 ext2_dirent * de;
490 unsigned long npages = dir_pages(dir);
491 unsigned long n;
492 loff_t pos;
493 int err;
494
495 /*
496 * We take care of directory expansion in the same loop.
497 * This code plays outside i_size, so it locks the page
498 * to protect that region.
499 */
500 for (n = 0; n <= npages; n++) {
501 char *kaddr = ext2_get_page(dir, n, 0, &page);
502 char *dir_end;
503
504 if (IS_ERR(kaddr))
505 return PTR_ERR(kaddr);
506 lock_page(page);
507 dir_end = kaddr + ext2_last_byte(dir, n);
508 de = (ext2_dirent *)kaddr;
509 kaddr += PAGE_SIZE - reclen;
510 while ((char *)de <= kaddr) {
511 if ((char *)de == dir_end) {
512 /* We hit i_size */
513 name_len = 0;
514 rec_len = chunk_size;
515 de->rec_len = ext2_rec_len_to_disk(chunk_size);
516 de->inode = 0;
517 goto got_it;
518 }
519 if (de->rec_len == 0) {
520 ext2_error(dir->i_sb, __func__,
521 "zero-length directory entry");
522 err = -EIO;
523 goto out_unlock;
524 }
525 err = -EEXIST;
526 if (ext2_match (namelen, name, de))
527 goto out_unlock;
528 name_len = EXT2_DIR_REC_LEN(de->name_len);
529 rec_len = ext2_rec_len_from_disk(de->rec_len);
530 if (!de->inode && rec_len >= reclen)
531 goto got_it;
532 if (rec_len >= name_len + reclen)
533 goto got_it;
534 de = (ext2_dirent *) ((char *) de + rec_len);
535 }
536 unlock_page(page);
537 ext2_put_page(page, kaddr);
538 }
539 BUG();
540 return -EINVAL;
541
542 got_it:
543 pos = page_offset(page) + offset_in_page(de);
544 err = ext2_prepare_chunk(page, pos, rec_len);
545 if (err)
546 goto out_unlock;
547 if (de->inode) {
548 ext2_dirent *de1 = (ext2_dirent *) ((char *) de + name_len);
549 de1->rec_len = ext2_rec_len_to_disk(rec_len - name_len);
550 de->rec_len = ext2_rec_len_to_disk(name_len);
551 de = de1;
552 }
553 de->name_len = namelen;
554 memcpy(de->name, name, namelen);
555 de->inode = cpu_to_le32(inode->i_ino);
556 ext2_set_de_type (de, inode);
557 ext2_commit_chunk(page, pos, rec_len);
558 dir->i_mtime = inode_set_ctime_current(dir);
559 EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL;
560 mark_inode_dirty(dir);
561 err = ext2_handle_dirsync(dir);
562 /* OFFSET_CACHE */
563 out_put:
564 ext2_put_page(page, de);
565 return err;
566 out_unlock:
567 unlock_page(page);
568 goto out_put;
569 }
570
571 /*
572 * ext2_delete_entry deletes a directory entry by merging it with the
573 * previous entry. Page is up-to-date.
574 */
ext2_delete_entry(struct ext2_dir_entry_2 * dir,struct page * page)575 int ext2_delete_entry(struct ext2_dir_entry_2 *dir, struct page *page)
576 {
577 struct inode *inode = page->mapping->host;
578 char *kaddr = (char *)((unsigned long)dir & PAGE_MASK);
579 unsigned from = offset_in_page(dir) & ~(ext2_chunk_size(inode)-1);
580 unsigned to = offset_in_page(dir) +
581 ext2_rec_len_from_disk(dir->rec_len);
582 loff_t pos;
583 ext2_dirent *pde = NULL;
584 ext2_dirent *de = (ext2_dirent *)(kaddr + from);
585 int err;
586
587 while ((char*)de < (char*)dir) {
588 if (de->rec_len == 0) {
589 ext2_error(inode->i_sb, __func__,
590 "zero-length directory entry");
591 return -EIO;
592 }
593 pde = de;
594 de = ext2_next_entry(de);
595 }
596 if (pde)
597 from = offset_in_page(pde);
598 pos = page_offset(page) + from;
599 lock_page(page);
600 err = ext2_prepare_chunk(page, pos, to - from);
601 if (err) {
602 unlock_page(page);
603 return err;
604 }
605 if (pde)
606 pde->rec_len = ext2_rec_len_to_disk(to - from);
607 dir->inode = 0;
608 ext2_commit_chunk(page, pos, to - from);
609 inode->i_mtime = inode_set_ctime_current(inode);
610 EXT2_I(inode)->i_flags &= ~EXT2_BTREE_FL;
611 mark_inode_dirty(inode);
612 return ext2_handle_dirsync(inode);
613 }
614
615 /*
616 * Set the first fragment of directory.
617 */
ext2_make_empty(struct inode * inode,struct inode * parent)618 int ext2_make_empty(struct inode *inode, struct inode *parent)
619 {
620 struct page *page = grab_cache_page(inode->i_mapping, 0);
621 unsigned chunk_size = ext2_chunk_size(inode);
622 struct ext2_dir_entry_2 * de;
623 int err;
624 void *kaddr;
625
626 if (!page)
627 return -ENOMEM;
628
629 err = ext2_prepare_chunk(page, 0, chunk_size);
630 if (err) {
631 unlock_page(page);
632 goto fail;
633 }
634 kaddr = kmap_local_page(page);
635 memset(kaddr, 0, chunk_size);
636 de = (struct ext2_dir_entry_2 *)kaddr;
637 de->name_len = 1;
638 de->rec_len = ext2_rec_len_to_disk(EXT2_DIR_REC_LEN(1));
639 memcpy (de->name, ".\0\0", 4);
640 de->inode = cpu_to_le32(inode->i_ino);
641 ext2_set_de_type (de, inode);
642
643 de = (struct ext2_dir_entry_2 *)(kaddr + EXT2_DIR_REC_LEN(1));
644 de->name_len = 2;
645 de->rec_len = ext2_rec_len_to_disk(chunk_size - EXT2_DIR_REC_LEN(1));
646 de->inode = cpu_to_le32(parent->i_ino);
647 memcpy (de->name, "..\0", 4);
648 ext2_set_de_type (de, inode);
649 kunmap_local(kaddr);
650 ext2_commit_chunk(page, 0, chunk_size);
651 err = ext2_handle_dirsync(inode);
652 fail:
653 put_page(page);
654 return err;
655 }
656
657 /*
658 * routine to check that the specified directory is empty (for rmdir)
659 */
ext2_empty_dir(struct inode * inode)660 int ext2_empty_dir (struct inode * inode)
661 {
662 struct page *page;
663 char *kaddr;
664 unsigned long i, npages = dir_pages(inode);
665
666 for (i = 0; i < npages; i++) {
667 ext2_dirent *de;
668
669 kaddr = ext2_get_page(inode, i, 0, &page);
670 if (IS_ERR(kaddr))
671 return 0;
672
673 de = (ext2_dirent *)kaddr;
674 kaddr += ext2_last_byte(inode, i) - EXT2_DIR_REC_LEN(1);
675
676 while ((char *)de <= kaddr) {
677 if (de->rec_len == 0) {
678 ext2_error(inode->i_sb, __func__,
679 "zero-length directory entry");
680 printk("kaddr=%p, de=%p\n", kaddr, de);
681 goto not_empty;
682 }
683 if (de->inode != 0) {
684 /* check for . and .. */
685 if (de->name[0] != '.')
686 goto not_empty;
687 if (de->name_len > 2)
688 goto not_empty;
689 if (de->name_len < 2) {
690 if (de->inode !=
691 cpu_to_le32(inode->i_ino))
692 goto not_empty;
693 } else if (de->name[1] != '.')
694 goto not_empty;
695 }
696 de = ext2_next_entry(de);
697 }
698 ext2_put_page(page, kaddr);
699 }
700 return 1;
701
702 not_empty:
703 ext2_put_page(page, kaddr);
704 return 0;
705 }
706
707 const struct file_operations ext2_dir_operations = {
708 .llseek = generic_file_llseek,
709 .read = generic_read_dir,
710 .iterate_shared = ext2_readdir,
711 .unlocked_ioctl = ext2_ioctl,
712 #ifdef CONFIG_COMPAT
713 .compat_ioctl = ext2_compat_ioctl,
714 #endif
715 .fsync = ext2_fsync,
716 };
717