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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
31typedef 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 */
38static 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
49static 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 */
64static 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 */
73static unsigned
74ext2_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
84static 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
99static 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;
134out:
135 SetPageChecked(page);
136 return true;
137
138 /* Too bad, we had an error */
139
140Ebadsize:
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;
146Eshort:
147 error = "rec_len is smaller than minimal";
148 goto bad_entry;
149Ealign:
150 error = "unaligned directory entry";
151 goto bad_entry;
152Enamelen:
153 error = "rec_len is too small for name_len";
154 goto bad_entry;
155Espan:
156 error = "directory entry across blocks";
157 goto bad_entry;
158Einumber:
159 error = "inode out of bounds";
160bad_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;
168Eend:
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 }
177fail:
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 */
189static struct page * ext2_get_page(struct inode *dir, unsigned long n,
190 int quiet, void **page_addr)
191{
192 struct address_space *mapping = dir->i_mapping;
193 struct folio *folio = read_mapping_folio(mapping, n, NULL);
194
195 if (IS_ERR(folio))
196 return &folio->page;
197 *page_addr = kmap_local_folio(folio, n & (folio_nr_pages(folio) - 1));
198 if (unlikely(!folio_test_checked(folio))) {
199 if (!ext2_check_page(&folio->page, quiet, *page_addr))
200 goto fail;
201 }
202 return &folio->page;
203
204fail:
205 ext2_put_page(&folio->page, *page_addr);
206 return ERR_PTR(-EIO);
207}
208
209/*
210 * NOTE! unlike strncmp, ext2_match returns 1 for success, 0 for failure.
211 *
212 * len <= EXT2_NAME_LEN and de != NULL are guaranteed by caller.
213 */
214static inline int ext2_match (int len, const char * const name,
215 struct ext2_dir_entry_2 * de)
216{
217 if (len != de->name_len)
218 return 0;
219 if (!de->inode)
220 return 0;
221 return !memcmp(name, de->name, len);
222}
223
224/*
225 * p is at least 6 bytes before the end of page
226 */
227static inline ext2_dirent *ext2_next_entry(ext2_dirent *p)
228{
229 return (ext2_dirent *)((char *)p +
230 ext2_rec_len_from_disk(p->rec_len));
231}
232
233static inline unsigned
234ext2_validate_entry(char *base, unsigned offset, unsigned mask)
235{
236 ext2_dirent *de = (ext2_dirent*)(base + offset);
237 ext2_dirent *p = (ext2_dirent*)(base + (offset&mask));
238 while ((char*)p < (char*)de) {
239 if (p->rec_len == 0)
240 break;
241 p = ext2_next_entry(p);
242 }
243 return (char *)p - base;
244}
245
246static inline void ext2_set_de_type(ext2_dirent *de, struct inode *inode)
247{
248 if (EXT2_HAS_INCOMPAT_FEATURE(inode->i_sb, EXT2_FEATURE_INCOMPAT_FILETYPE))
249 de->file_type = fs_umode_to_ftype(inode->i_mode);
250 else
251 de->file_type = 0;
252}
253
254static int
255ext2_readdir(struct file *file, struct dir_context *ctx)
256{
257 loff_t pos = ctx->pos;
258 struct inode *inode = file_inode(file);
259 struct super_block *sb = inode->i_sb;
260 unsigned int offset = pos & ~PAGE_MASK;
261 unsigned long n = pos >> PAGE_SHIFT;
262 unsigned long npages = dir_pages(inode);
263 unsigned chunk_mask = ~(ext2_chunk_size(inode)-1);
264 bool need_revalidate = !inode_eq_iversion(inode, file->f_version);
265 bool has_filetype;
266
267 if (pos > inode->i_size - EXT2_DIR_REC_LEN(1))
268 return 0;
269
270 has_filetype =
271 EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_FILETYPE);
272
273 for ( ; n < npages; n++, offset = 0) {
274 char *kaddr, *limit;
275 ext2_dirent *de;
276 struct page *page = ext2_get_page(inode, n, 0, (void **)&kaddr);
277
278 if (IS_ERR(page)) {
279 ext2_error(sb, __func__,
280 "bad page in #%lu",
281 inode->i_ino);
282 ctx->pos += PAGE_SIZE - offset;
283 return PTR_ERR(page);
284 }
285 if (unlikely(need_revalidate)) {
286 if (offset) {
287 offset = ext2_validate_entry(kaddr, offset, chunk_mask);
288 ctx->pos = (n<<PAGE_SHIFT) + offset;
289 }
290 file->f_version = inode_query_iversion(inode);
291 need_revalidate = false;
292 }
293 de = (ext2_dirent *)(kaddr+offset);
294 limit = kaddr + ext2_last_byte(inode, n) - EXT2_DIR_REC_LEN(1);
295 for ( ;(char*)de <= limit; de = ext2_next_entry(de)) {
296 if (de->rec_len == 0) {
297 ext2_error(sb, __func__,
298 "zero-length directory entry");
299 ext2_put_page(page, kaddr);
300 return -EIO;
301 }
302 if (de->inode) {
303 unsigned char d_type = DT_UNKNOWN;
304
305 if (has_filetype)
306 d_type = fs_ftype_to_dtype(de->file_type);
307
308 if (!dir_emit(ctx, de->name, de->name_len,
309 le32_to_cpu(de->inode),
310 d_type)) {
311 ext2_put_page(page, kaddr);
312 return 0;
313 }
314 }
315 ctx->pos += ext2_rec_len_from_disk(de->rec_len);
316 }
317 ext2_put_page(page, kaddr);
318 }
319 return 0;
320}
321
322/*
323 * ext2_find_entry()
324 *
325 * finds an entry in the specified directory with the wanted name. It
326 * returns the page in which the entry was found (as a parameter - res_page),
327 * and the entry itself. Page is returned mapped and unlocked.
328 * Entry is guaranteed to be valid.
329 *
330 * On Success ext2_put_page() should be called on *res_page.
331 *
332 * NOTE: Calls to ext2_get_page()/ext2_put_page() must be nested according to
333 * the rules documented in kmap_local_page()/kunmap_local().
334 *
335 * ext2_find_entry() and ext2_dotdot() act as a call to ext2_get_page() and
336 * should be treated as a call to ext2_get_page() for nesting purposes.
337 */
338struct ext2_dir_entry_2 *ext2_find_entry (struct inode *dir,
339 const struct qstr *child, struct page **res_page,
340 void **res_page_addr)
341{
342 const char *name = child->name;
343 int namelen = child->len;
344 unsigned reclen = EXT2_DIR_REC_LEN(namelen);
345 unsigned long start, n;
346 unsigned long npages = dir_pages(dir);
347 struct page *page = NULL;
348 struct ext2_inode_info *ei = EXT2_I(dir);
349 ext2_dirent * de;
350 void *page_addr;
351
352 if (npages == 0)
353 goto out;
354
355 /* OFFSET_CACHE */
356 *res_page = NULL;
357 *res_page_addr = NULL;
358
359 start = ei->i_dir_start_lookup;
360 if (start >= npages)
361 start = 0;
362 n = start;
363 do {
364 char *kaddr;
365 page = ext2_get_page(dir, n, 0, &page_addr);
366 if (IS_ERR(page))
367 return ERR_CAST(page);
368
369 kaddr = page_addr;
370 de = (ext2_dirent *) kaddr;
371 kaddr += ext2_last_byte(dir, n) - reclen;
372 while ((char *) de <= kaddr) {
373 if (de->rec_len == 0) {
374 ext2_error(dir->i_sb, __func__,
375 "zero-length directory entry");
376 ext2_put_page(page, page_addr);
377 goto out;
378 }
379 if (ext2_match(namelen, name, de))
380 goto found;
381 de = ext2_next_entry(de);
382 }
383 ext2_put_page(page, page_addr);
384
385 if (++n >= npages)
386 n = 0;
387 /* next page is past the blocks we've got */
388 if (unlikely(n > (dir->i_blocks >> (PAGE_SHIFT - 9)))) {
389 ext2_error(dir->i_sb, __func__,
390 "dir %lu size %lld exceeds block count %llu",
391 dir->i_ino, dir->i_size,
392 (unsigned long long)dir->i_blocks);
393 goto out;
394 }
395 } while (n != start);
396out:
397 return ERR_PTR(-ENOENT);
398
399found:
400 *res_page = page;
401 *res_page_addr = page_addr;
402 ei->i_dir_start_lookup = n;
403 return de;
404}
405
406/*
407 * Return the '..' directory entry and the page in which the entry was found
408 * (as a parameter - p).
409 *
410 * On Success ext2_put_page() should be called on *p.
411 *
412 * NOTE: Calls to ext2_get_page()/ext2_put_page() must be nested according to
413 * the rules documented in kmap_local_page()/kunmap_local().
414 *
415 * ext2_find_entry() and ext2_dotdot() act as a call to ext2_get_page() and
416 * should be treated as a call to ext2_get_page() for nesting purposes.
417 */
418struct ext2_dir_entry_2 *ext2_dotdot(struct inode *dir, struct page **p,
419 void **pa)
420{
421 void *page_addr;
422 struct page *page = ext2_get_page(dir, 0, 0, &page_addr);
423 ext2_dirent *de = NULL;
424
425 if (!IS_ERR(page)) {
426 de = ext2_next_entry((ext2_dirent *) page_addr);
427 *p = page;
428 *pa = page_addr;
429 }
430 return de;
431}
432
433int ext2_inode_by_name(struct inode *dir, const struct qstr *child, ino_t *ino)
434{
435 struct ext2_dir_entry_2 *de;
436 struct page *page;
437 void *page_addr;
438
439 de = ext2_find_entry(dir, child, &page, &page_addr);
440 if (IS_ERR(de))
441 return PTR_ERR(de);
442
443 *ino = le32_to_cpu(de->inode);
444 ext2_put_page(page, page_addr);
445 return 0;
446}
447
448static int ext2_prepare_chunk(struct page *page, loff_t pos, unsigned len)
449{
450 return __block_write_begin(page, pos, len, ext2_get_block);
451}
452
453
454static int ext2_handle_dirsync(struct inode *dir)
455{
456 int err;
457
458 err = filemap_write_and_wait(dir->i_mapping);
459 if (!err)
460 err = sync_inode_metadata(dir, 1);
461 return err;
462}
463
464void ext2_set_link(struct inode *dir, struct ext2_dir_entry_2 *de,
465 struct page *page, void *page_addr, struct inode *inode,
466 int update_times)
467{
468 loff_t pos = page_offset(page) +
469 (char *) de - (char *) page_addr;
470 unsigned len = ext2_rec_len_from_disk(de->rec_len);
471 int err;
472
473 lock_page(page);
474 err = ext2_prepare_chunk(page, pos, len);
475 BUG_ON(err);
476 de->inode = cpu_to_le32(inode->i_ino);
477 ext2_set_de_type(de, inode);
478 ext2_commit_chunk(page, pos, len);
479 if (update_times)
480 dir->i_mtime = dir->i_ctime = current_time(dir);
481 EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL;
482 mark_inode_dirty(dir);
483 ext2_handle_dirsync(dir);
484}
485
486/*
487 * Parent is locked.
488 */
489int ext2_add_link (struct dentry *dentry, struct inode *inode)
490{
491 struct inode *dir = d_inode(dentry->d_parent);
492 const char *name = dentry->d_name.name;
493 int namelen = dentry->d_name.len;
494 unsigned chunk_size = ext2_chunk_size(dir);
495 unsigned reclen = EXT2_DIR_REC_LEN(namelen);
496 unsigned short rec_len, name_len;
497 struct page *page = NULL;
498 void *page_addr = NULL;
499 ext2_dirent * de;
500 unsigned long npages = dir_pages(dir);
501 unsigned long n;
502 loff_t pos;
503 int err;
504
505 /*
506 * We take care of directory expansion in the same loop.
507 * This code plays outside i_size, so it locks the page
508 * to protect that region.
509 */
510 for (n = 0; n <= npages; n++) {
511 char *kaddr;
512 char *dir_end;
513
514 page = ext2_get_page(dir, n, 0, &page_addr);
515 err = PTR_ERR(page);
516 if (IS_ERR(page))
517 goto out;
518 lock_page(page);
519 kaddr = page_addr;
520 dir_end = kaddr + ext2_last_byte(dir, n);
521 de = (ext2_dirent *)kaddr;
522 kaddr += PAGE_SIZE - reclen;
523 while ((char *)de <= kaddr) {
524 if ((char *)de == dir_end) {
525 /* We hit i_size */
526 name_len = 0;
527 rec_len = chunk_size;
528 de->rec_len = ext2_rec_len_to_disk(chunk_size);
529 de->inode = 0;
530 goto got_it;
531 }
532 if (de->rec_len == 0) {
533 ext2_error(dir->i_sb, __func__,
534 "zero-length directory entry");
535 err = -EIO;
536 goto out_unlock;
537 }
538 err = -EEXIST;
539 if (ext2_match (namelen, name, de))
540 goto out_unlock;
541 name_len = EXT2_DIR_REC_LEN(de->name_len);
542 rec_len = ext2_rec_len_from_disk(de->rec_len);
543 if (!de->inode && rec_len >= reclen)
544 goto got_it;
545 if (rec_len >= name_len + reclen)
546 goto got_it;
547 de = (ext2_dirent *) ((char *) de + rec_len);
548 }
549 unlock_page(page);
550 ext2_put_page(page, page_addr);
551 }
552 BUG();
553 return -EINVAL;
554
555got_it:
556 pos = page_offset(page) +
557 (char *)de - (char *)page_addr;
558 err = ext2_prepare_chunk(page, pos, rec_len);
559 if (err)
560 goto out_unlock;
561 if (de->inode) {
562 ext2_dirent *de1 = (ext2_dirent *) ((char *) de + name_len);
563 de1->rec_len = ext2_rec_len_to_disk(rec_len - name_len);
564 de->rec_len = ext2_rec_len_to_disk(name_len);
565 de = de1;
566 }
567 de->name_len = namelen;
568 memcpy(de->name, name, namelen);
569 de->inode = cpu_to_le32(inode->i_ino);
570 ext2_set_de_type (de, inode);
571 ext2_commit_chunk(page, pos, rec_len);
572 dir->i_mtime = dir->i_ctime = current_time(dir);
573 EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL;
574 mark_inode_dirty(dir);
575 err = ext2_handle_dirsync(dir);
576 /* OFFSET_CACHE */
577out_put:
578 ext2_put_page(page, page_addr);
579out:
580 return err;
581out_unlock:
582 unlock_page(page);
583 goto out_put;
584}
585
586/*
587 * ext2_delete_entry deletes a directory entry by merging it with the
588 * previous entry. Page is up-to-date.
589 */
590int ext2_delete_entry (struct ext2_dir_entry_2 *dir, struct page *page,
591 char *kaddr)
592{
593 struct inode *inode = page->mapping->host;
594 unsigned from = ((char*)dir - kaddr) & ~(ext2_chunk_size(inode)-1);
595 unsigned to = ((char *)dir - kaddr) +
596 ext2_rec_len_from_disk(dir->rec_len);
597 loff_t pos;
598 ext2_dirent * pde = NULL;
599 ext2_dirent * de = (ext2_dirent *) (kaddr + from);
600 int err;
601
602 while ((char*)de < (char*)dir) {
603 if (de->rec_len == 0) {
604 ext2_error(inode->i_sb, __func__,
605 "zero-length directory entry");
606 err = -EIO;
607 goto out;
608 }
609 pde = de;
610 de = ext2_next_entry(de);
611 }
612 if (pde)
613 from = (char *)pde - kaddr;
614 pos = page_offset(page) + from;
615 lock_page(page);
616 err = ext2_prepare_chunk(page, pos, to - from);
617 BUG_ON(err);
618 if (pde)
619 pde->rec_len = ext2_rec_len_to_disk(to - from);
620 dir->inode = 0;
621 ext2_commit_chunk(page, pos, to - from);
622 inode->i_ctime = inode->i_mtime = current_time(inode);
623 EXT2_I(inode)->i_flags &= ~EXT2_BTREE_FL;
624 mark_inode_dirty(inode);
625 err = ext2_handle_dirsync(inode);
626out:
627 return err;
628}
629
630/*
631 * Set the first fragment of directory.
632 */
633int ext2_make_empty(struct inode *inode, struct inode *parent)
634{
635 struct page *page = grab_cache_page(inode->i_mapping, 0);
636 unsigned chunk_size = ext2_chunk_size(inode);
637 struct ext2_dir_entry_2 * de;
638 int err;
639 void *kaddr;
640
641 if (!page)
642 return -ENOMEM;
643
644 err = ext2_prepare_chunk(page, 0, chunk_size);
645 if (err) {
646 unlock_page(page);
647 goto fail;
648 }
649 kaddr = kmap_atomic(page);
650 memset(kaddr, 0, chunk_size);
651 de = (struct ext2_dir_entry_2 *)kaddr;
652 de->name_len = 1;
653 de->rec_len = ext2_rec_len_to_disk(EXT2_DIR_REC_LEN(1));
654 memcpy (de->name, ".\0\0", 4);
655 de->inode = cpu_to_le32(inode->i_ino);
656 ext2_set_de_type (de, inode);
657
658 de = (struct ext2_dir_entry_2 *)(kaddr + EXT2_DIR_REC_LEN(1));
659 de->name_len = 2;
660 de->rec_len = ext2_rec_len_to_disk(chunk_size - EXT2_DIR_REC_LEN(1));
661 de->inode = cpu_to_le32(parent->i_ino);
662 memcpy (de->name, "..\0", 4);
663 ext2_set_de_type (de, inode);
664 kunmap_atomic(kaddr);
665 ext2_commit_chunk(page, 0, chunk_size);
666 err = ext2_handle_dirsync(inode);
667fail:
668 put_page(page);
669 return err;
670}
671
672/*
673 * routine to check that the specified directory is empty (for rmdir)
674 */
675int ext2_empty_dir (struct inode * inode)
676{
677 void *page_addr = NULL;
678 struct page *page = NULL;
679 unsigned long i, npages = dir_pages(inode);
680
681 for (i = 0; i < npages; i++) {
682 char *kaddr;
683 ext2_dirent * de;
684 page = ext2_get_page(inode, i, 0, &page_addr);
685
686 if (IS_ERR(page))
687 return 0;
688
689 kaddr = page_addr;
690 de = (ext2_dirent *)kaddr;
691 kaddr += ext2_last_byte(inode, i) - EXT2_DIR_REC_LEN(1);
692
693 while ((char *)de <= kaddr) {
694 if (de->rec_len == 0) {
695 ext2_error(inode->i_sb, __func__,
696 "zero-length directory entry");
697 printk("kaddr=%p, de=%p\n", kaddr, de);
698 goto not_empty;
699 }
700 if (de->inode != 0) {
701 /* check for . and .. */
702 if (de->name[0] != '.')
703 goto not_empty;
704 if (de->name_len > 2)
705 goto not_empty;
706 if (de->name_len < 2) {
707 if (de->inode !=
708 cpu_to_le32(inode->i_ino))
709 goto not_empty;
710 } else if (de->name[1] != '.')
711 goto not_empty;
712 }
713 de = ext2_next_entry(de);
714 }
715 ext2_put_page(page, page_addr);
716 }
717 return 1;
718
719not_empty:
720 ext2_put_page(page, page_addr);
721 return 0;
722}
723
724const struct file_operations ext2_dir_operations = {
725 .llseek = generic_file_llseek,
726 .read = generic_read_dir,
727 .iterate_shared = ext2_readdir,
728 .unlocked_ioctl = ext2_ioctl,
729#ifdef CONFIG_COMPAT
730 .compat_ioctl = ext2_compat_ioctl,
731#endif
732 .fsync = ext2_fsync,
733};
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
31typedef 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 */
38static 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
49static 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 */
64static inline unsigned ext2_chunk_size(struct inode *inode)
65{
66 return inode->i_sb->s_blocksize;
67}
68
69static 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 */
79static unsigned
80ext2_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
90static 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
115static 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;
151out:
152 SetPageChecked(page);
153 return true;
154
155 /* Too bad, we had an error */
156
157Ebadsize:
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;
163Eshort:
164 error = "rec_len is smaller than minimal";
165 goto bad_entry;
166Ealign:
167 error = "unaligned directory entry";
168 goto bad_entry;
169Enamelen:
170 error = "rec_len is too small for name_len";
171 goto bad_entry;
172Espan:
173 error = "directory entry across blocks";
174 goto bad_entry;
175Einumber:
176 error = "inode out of bounds";
177bad_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;
185Eend:
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 }
194fail:
195 SetPageError(page);
196 return false;
197}
198
199static 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
213fail:
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 */
223static 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 */
236static 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
242static inline unsigned
243ext2_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
255static 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
267static 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
277static 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
286static int
287ext2_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 */
363struct 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);
419out:
420 return NULL;
421
422found:
423 *res_page = page;
424 ei->i_dir_start_lookup = n;
425 return de;
426}
427
428struct 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
440ino_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
454static 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 */
460void 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 */
484int 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
549got_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 */
570out_put:
571 ext2_put_page(page);
572out:
573 return err;
574out_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 */
583int 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);
618out:
619 ext2_put_page(page);
620 return err;
621}
622
623/*
624 * Set the first fragment of directory.
625 */
626int 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);
659fail:
660 put_page(page);
661 return err;
662}
663
664/*
665 * routine to check that the specified directory is empty (for rmdir)
666 */
667int 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
713not_empty:
714 ext2_put_page(page);
715 return 0;
716}
717
718const 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};