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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
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 folio *folio, loff_t pos, unsigned len)
85{
86 struct address_space *mapping = folio->mapping;
87 struct inode *dir = mapping->host;
88
89 inode_inc_iversion(dir);
90 block_write_end(NULL, mapping, pos, len, len, folio, NULL);
91
92 if (pos+len > dir->i_size) {
93 i_size_write(dir, pos+len);
94 mark_inode_dirty(dir);
95 }
96 folio_unlock(folio);
97}
98
99static bool ext2_check_folio(struct folio *folio, int quiet, char *kaddr)
100{
101 struct inode *dir = folio->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 = folio_size(folio);
107 ext2_dirent *p;
108 char *error;
109
110 if (dir->i_size < folio_pos(folio) + limit) {
111 limit = offset_in_folio(folio, dir->i_size);
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 folio_set_checked(folio);
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=%llu, inode=%lu, rec_len=%d, name_len=%d",
164 dir->i_ino, error, folio_pos(folio) + 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_folio",
172 "entry in directory #%lu spans the page boundary"
173 "offset=%llu, inode=%lu",
174 dir->i_ino, folio_pos(folio) + offs,
175 (unsigned long) le32_to_cpu(p->inode));
176 }
177fail:
178 return false;
179}
180
181/*
182 * Calls to ext2_get_folio()/folio_release_kmap() must be nested according
183 * to the rules documented in kmap_local_folio()/kunmap_local().
184 *
185 * NOTE: ext2_find_entry() and ext2_dotdot() act as a call
186 * to folio_release_kmap() and should be treated as a call to
187 * folio_release_kmap() for nesting purposes.
188 */
189static void *ext2_get_folio(struct inode *dir, unsigned long n,
190 int quiet, struct folio **foliop)
191{
192 struct address_space *mapping = dir->i_mapping;
193 struct folio *folio = read_mapping_folio(mapping, n, NULL);
194 void *kaddr;
195
196 if (IS_ERR(folio))
197 return ERR_CAST(folio);
198 kaddr = kmap_local_folio(folio, 0);
199 if (unlikely(!folio_test_checked(folio))) {
200 if (!ext2_check_folio(folio, quiet, kaddr))
201 goto fail;
202 }
203 *foliop = folio;
204 return kaddr;
205
206fail:
207 folio_release_kmap(folio, kaddr);
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 */
216static 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 */
229static 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
235static inline unsigned
236ext2_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
248static 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
256static int
257ext2_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, *(u64 *)file->private_data);
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 folio *folio;
278 char *kaddr = ext2_get_folio(inode, n, 0, &folio);
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 *(u64 *)file->private_data = 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 folio_release_kmap(folio, 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 folio_release_kmap(folio, de);
315 return 0;
316 }
317 }
318 ctx->pos += ext2_rec_len_from_disk(de->rec_len);
319 }
320 folio_release_kmap(folio, 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 folio_release_kmap() should be called on *foliop.
334 *
335 * NOTE: Calls to ext2_get_folio()/folio_release_kmap() must be nested
336 * according to the rules documented in kmap_local_folio()/kunmap_local().
337 *
338 * ext2_find_entry() and ext2_dotdot() act as a call to ext2_get_folio()
339 * and should be treated as a call to ext2_get_folio() for nesting
340 * purposes.
341 */
342struct ext2_dir_entry_2 *ext2_find_entry (struct inode *dir,
343 const struct qstr *child, struct folio **foliop)
344{
345 const char *name = child->name;
346 int namelen = child->len;
347 unsigned reclen = EXT2_DIR_REC_LEN(namelen);
348 unsigned long start, n;
349 unsigned long npages = dir_pages(dir);
350 struct ext2_inode_info *ei = EXT2_I(dir);
351 ext2_dirent * de;
352
353 if (npages == 0)
354 goto out;
355
356 start = ei->i_dir_start_lookup;
357 if (start >= npages)
358 start = 0;
359 n = start;
360 do {
361 char *kaddr = ext2_get_folio(dir, n, 0, foliop);
362 if (IS_ERR(kaddr))
363 return ERR_CAST(kaddr);
364
365 de = (ext2_dirent *) kaddr;
366 kaddr += ext2_last_byte(dir, n) - reclen;
367 while ((char *) de <= kaddr) {
368 if (de->rec_len == 0) {
369 ext2_error(dir->i_sb, __func__,
370 "zero-length directory entry");
371 folio_release_kmap(*foliop, de);
372 goto out;
373 }
374 if (ext2_match(namelen, name, de))
375 goto found;
376 de = ext2_next_entry(de);
377 }
378 folio_release_kmap(*foliop, kaddr);
379
380 if (++n >= npages)
381 n = 0;
382 /* next folio is past the blocks we've got */
383 if (unlikely(n > (dir->i_blocks >> (PAGE_SHIFT - 9)))) {
384 ext2_error(dir->i_sb, __func__,
385 "dir %lu size %lld exceeds block count %llu",
386 dir->i_ino, dir->i_size,
387 (unsigned long long)dir->i_blocks);
388 goto out;
389 }
390 } while (n != start);
391out:
392 return ERR_PTR(-ENOENT);
393
394found:
395 ei->i_dir_start_lookup = n;
396 return de;
397}
398
399/*
400 * Return the '..' directory entry and the page in which the entry was found
401 * (as a parameter - p).
402 *
403 * On Success folio_release_kmap() should be called on *foliop.
404 *
405 * NOTE: Calls to ext2_get_folio()/folio_release_kmap() must be nested
406 * according to the rules documented in kmap_local_folio()/kunmap_local().
407 *
408 * ext2_find_entry() and ext2_dotdot() act as a call to ext2_get_folio()
409 * and should be treated as a call to ext2_get_folio() for nesting
410 * purposes.
411 */
412struct ext2_dir_entry_2 *ext2_dotdot(struct inode *dir, struct folio **foliop)
413{
414 ext2_dirent *de = ext2_get_folio(dir, 0, 0, foliop);
415
416 if (!IS_ERR(de))
417 return ext2_next_entry(de);
418 return NULL;
419}
420
421int ext2_inode_by_name(struct inode *dir, const struct qstr *child, ino_t *ino)
422{
423 struct ext2_dir_entry_2 *de;
424 struct folio *folio;
425
426 de = ext2_find_entry(dir, child, &folio);
427 if (IS_ERR(de))
428 return PTR_ERR(de);
429
430 *ino = le32_to_cpu(de->inode);
431 folio_release_kmap(folio, de);
432 return 0;
433}
434
435static int ext2_prepare_chunk(struct folio *folio, loff_t pos, unsigned len)
436{
437 return __block_write_begin(folio, pos, len, ext2_get_block);
438}
439
440static int ext2_handle_dirsync(struct inode *dir)
441{
442 int err;
443
444 err = filemap_write_and_wait(dir->i_mapping);
445 if (!err)
446 err = sync_inode_metadata(dir, 1);
447 return err;
448}
449
450int ext2_set_link(struct inode *dir, struct ext2_dir_entry_2 *de,
451 struct folio *folio, struct inode *inode, bool update_times)
452{
453 loff_t pos = folio_pos(folio) + offset_in_folio(folio, de);
454 unsigned len = ext2_rec_len_from_disk(de->rec_len);
455 int err;
456
457 folio_lock(folio);
458 err = ext2_prepare_chunk(folio, pos, len);
459 if (err) {
460 folio_unlock(folio);
461 return err;
462 }
463 de->inode = cpu_to_le32(inode->i_ino);
464 ext2_set_de_type(de, inode);
465 ext2_commit_chunk(folio, pos, len);
466 if (update_times)
467 inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir));
468 EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL;
469 mark_inode_dirty(dir);
470 return ext2_handle_dirsync(dir);
471}
472
473/*
474 * Parent is locked.
475 */
476int ext2_add_link (struct dentry *dentry, struct inode *inode)
477{
478 struct inode *dir = d_inode(dentry->d_parent);
479 const char *name = dentry->d_name.name;
480 int namelen = dentry->d_name.len;
481 unsigned chunk_size = ext2_chunk_size(dir);
482 unsigned reclen = EXT2_DIR_REC_LEN(namelen);
483 unsigned short rec_len, name_len;
484 struct folio *folio = NULL;
485 ext2_dirent * de;
486 unsigned long npages = dir_pages(dir);
487 unsigned long n;
488 loff_t pos;
489 int err;
490
491 /*
492 * We take care of directory expansion in the same loop.
493 * This code plays outside i_size, so it locks the folio
494 * to protect that region.
495 */
496 for (n = 0; n <= npages; n++) {
497 char *kaddr = ext2_get_folio(dir, n, 0, &folio);
498 char *dir_end;
499
500 if (IS_ERR(kaddr))
501 return PTR_ERR(kaddr);
502 folio_lock(folio);
503 dir_end = kaddr + ext2_last_byte(dir, n);
504 de = (ext2_dirent *)kaddr;
505 kaddr += folio_size(folio) - reclen;
506 while ((char *)de <= kaddr) {
507 if ((char *)de == dir_end) {
508 /* We hit i_size */
509 name_len = 0;
510 rec_len = chunk_size;
511 de->rec_len = ext2_rec_len_to_disk(chunk_size);
512 de->inode = 0;
513 goto got_it;
514 }
515 if (de->rec_len == 0) {
516 ext2_error(dir->i_sb, __func__,
517 "zero-length directory entry");
518 err = -EIO;
519 goto out_unlock;
520 }
521 err = -EEXIST;
522 if (ext2_match (namelen, name, de))
523 goto out_unlock;
524 name_len = EXT2_DIR_REC_LEN(de->name_len);
525 rec_len = ext2_rec_len_from_disk(de->rec_len);
526 if (!de->inode && rec_len >= reclen)
527 goto got_it;
528 if (rec_len >= name_len + reclen)
529 goto got_it;
530 de = (ext2_dirent *) ((char *) de + rec_len);
531 }
532 folio_unlock(folio);
533 folio_release_kmap(folio, kaddr);
534 }
535 BUG();
536 return -EINVAL;
537
538got_it:
539 pos = folio_pos(folio) + offset_in_folio(folio, de);
540 err = ext2_prepare_chunk(folio, pos, rec_len);
541 if (err)
542 goto out_unlock;
543 if (de->inode) {
544 ext2_dirent *de1 = (ext2_dirent *) ((char *) de + name_len);
545 de1->rec_len = ext2_rec_len_to_disk(rec_len - name_len);
546 de->rec_len = ext2_rec_len_to_disk(name_len);
547 de = de1;
548 }
549 de->name_len = namelen;
550 memcpy(de->name, name, namelen);
551 de->inode = cpu_to_le32(inode->i_ino);
552 ext2_set_de_type (de, inode);
553 ext2_commit_chunk(folio, pos, rec_len);
554 inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir));
555 EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL;
556 mark_inode_dirty(dir);
557 err = ext2_handle_dirsync(dir);
558 /* OFFSET_CACHE */
559out_put:
560 folio_release_kmap(folio, de);
561 return err;
562out_unlock:
563 folio_unlock(folio);
564 goto out_put;
565}
566
567/*
568 * ext2_delete_entry deletes a directory entry by merging it with the
569 * previous entry. Page is up-to-date.
570 */
571int ext2_delete_entry(struct ext2_dir_entry_2 *dir, struct folio *folio)
572{
573 struct inode *inode = folio->mapping->host;
574 size_t from, to;
575 char *kaddr;
576 loff_t pos;
577 ext2_dirent *de, *pde = NULL;
578 int err;
579
580 from = offset_in_folio(folio, dir);
581 to = from + ext2_rec_len_from_disk(dir->rec_len);
582 kaddr = (char *)dir - from;
583 from &= ~(ext2_chunk_size(inode)-1);
584 de = (ext2_dirent *)(kaddr + from);
585
586 while ((char*)de < (char*)dir) {
587 if (de->rec_len == 0) {
588 ext2_error(inode->i_sb, __func__,
589 "zero-length directory entry");
590 return -EIO;
591 }
592 pde = de;
593 de = ext2_next_entry(de);
594 }
595 if (pde)
596 from = offset_in_folio(folio, pde);
597 pos = folio_pos(folio) + from;
598 folio_lock(folio);
599 err = ext2_prepare_chunk(folio, pos, to - from);
600 if (err) {
601 folio_unlock(folio);
602 return err;
603 }
604 if (pde)
605 pde->rec_len = ext2_rec_len_to_disk(to - from);
606 dir->inode = 0;
607 ext2_commit_chunk(folio, pos, to - from);
608 inode_set_mtime_to_ts(inode, inode_set_ctime_current(inode));
609 EXT2_I(inode)->i_flags &= ~EXT2_BTREE_FL;
610 mark_inode_dirty(inode);
611 return ext2_handle_dirsync(inode);
612}
613
614/*
615 * Set the first fragment of directory.
616 */
617int ext2_make_empty(struct inode *inode, struct inode *parent)
618{
619 struct folio *folio = filemap_grab_folio(inode->i_mapping, 0);
620 unsigned chunk_size = ext2_chunk_size(inode);
621 struct ext2_dir_entry_2 * de;
622 int err;
623 void *kaddr;
624
625 if (IS_ERR(folio))
626 return PTR_ERR(folio);
627
628 err = ext2_prepare_chunk(folio, 0, chunk_size);
629 if (err) {
630 folio_unlock(folio);
631 goto fail;
632 }
633 kaddr = kmap_local_folio(folio, 0);
634 memset(kaddr, 0, chunk_size);
635 de = (struct ext2_dir_entry_2 *)kaddr;
636 de->name_len = 1;
637 de->rec_len = ext2_rec_len_to_disk(EXT2_DIR_REC_LEN(1));
638 memcpy (de->name, ".\0\0", 4);
639 de->inode = cpu_to_le32(inode->i_ino);
640 ext2_set_de_type (de, inode);
641
642 de = (struct ext2_dir_entry_2 *)(kaddr + EXT2_DIR_REC_LEN(1));
643 de->name_len = 2;
644 de->rec_len = ext2_rec_len_to_disk(chunk_size - EXT2_DIR_REC_LEN(1));
645 de->inode = cpu_to_le32(parent->i_ino);
646 memcpy (de->name, "..\0", 4);
647 ext2_set_de_type (de, inode);
648 kunmap_local(kaddr);
649 ext2_commit_chunk(folio, 0, chunk_size);
650 err = ext2_handle_dirsync(inode);
651fail:
652 folio_put(folio);
653 return err;
654}
655
656/*
657 * routine to check that the specified directory is empty (for rmdir)
658 */
659int ext2_empty_dir(struct inode *inode)
660{
661 struct folio *folio;
662 char *kaddr;
663 unsigned long i, npages = dir_pages(inode);
664
665 for (i = 0; i < npages; i++) {
666 ext2_dirent *de;
667
668 kaddr = ext2_get_folio(inode, i, 0, &folio);
669 if (IS_ERR(kaddr))
670 return 0;
671
672 de = (ext2_dirent *)kaddr;
673 kaddr += ext2_last_byte(inode, i) - EXT2_DIR_REC_LEN(1);
674
675 while ((char *)de <= kaddr) {
676 if (de->rec_len == 0) {
677 ext2_error(inode->i_sb, __func__,
678 "zero-length directory entry");
679 printk("kaddr=%p, de=%p\n", kaddr, de);
680 goto not_empty;
681 }
682 if (de->inode != 0) {
683 /* check for . and .. */
684 if (de->name[0] != '.')
685 goto not_empty;
686 if (de->name_len > 2)
687 goto not_empty;
688 if (de->name_len < 2) {
689 if (de->inode !=
690 cpu_to_le32(inode->i_ino))
691 goto not_empty;
692 } else if (de->name[1] != '.')
693 goto not_empty;
694 }
695 de = ext2_next_entry(de);
696 }
697 folio_release_kmap(folio, kaddr);
698 }
699 return 1;
700
701not_empty:
702 folio_release_kmap(folio, kaddr);
703 return 0;
704}
705
706static int ext2_dir_open(struct inode *inode, struct file *file)
707{
708 file->private_data = kzalloc(sizeof(u64), GFP_KERNEL);
709 if (!file->private_data)
710 return -ENOMEM;
711 return 0;
712}
713
714static int ext2_dir_release(struct inode *inode, struct file *file)
715{
716 kfree(file->private_data);
717 return 0;
718}
719
720static loff_t ext2_dir_llseek(struct file *file, loff_t offset, int whence)
721{
722 return generic_llseek_cookie(file, offset, whence,
723 (u64 *)file->private_data);
724}
725
726const struct file_operations ext2_dir_operations = {
727 .open = ext2_dir_open,
728 .release = ext2_dir_release,
729 .llseek = ext2_dir_llseek,
730 .read = generic_read_dir,
731 .iterate_shared = ext2_readdir,
732 .unlocked_ioctl = ext2_ioctl,
733#ifdef CONFIG_COMPAT
734 .compat_ioctl = ext2_compat_ioctl,
735#endif
736 .fsync = ext2_fsync,
737};