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