xref: /linux/fs/ufs/dir.c (revision 3213486f2e442831e324cc6201a2f9e924ecc235) 
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *  linux/fs/ufs/ufs_dir.c
4  *
5  * Copyright (C) 1996
6  * Adrian Rodriguez (adrian@franklins-tower.rutgers.edu)
7  * Laboratory for Computer Science Research Computing Facility
8  * Rutgers, The State University of New Jersey
9  *
10  * swab support by Francois-Rene Rideau <fare@tunes.org> 19970406
11  *
12  * 4.4BSD (FreeBSD) support added on February 1st 1998 by
13  * Niels Kristian Bech Jensen <nkbj@image.dk> partially based
14  * on code by Martin von Loewis <martin@mira.isdn.cs.tu-berlin.de>.
15  *
16  * Migration to usage of "page cache" on May 2006 by
17  * Evgeniy Dushistov <dushistov@mail.ru> based on ext2 code base.
18  */
19 
20 #include <linux/time.h>
21 #include <linux/fs.h>
22 #include <linux/swap.h>
23 #include <linux/iversion.h>
24 
25 #include "ufs_fs.h"
26 #include "ufs.h"
27 #include "swab.h"
28 #include "util.h"
29 
30 /*
31  * NOTE! unlike strncmp, ufs_match returns 1 for success, 0 for failure.
32  *
33  * len <= UFS_MAXNAMLEN and de != NULL are guaranteed by caller.
34  */
35 static inline int ufs_match(struct super_block *sb, int len,
36 		const unsigned char *name, struct ufs_dir_entry *de)
37 {
38 	if (len != ufs_get_de_namlen(sb, de))
39 		return 0;
40 	if (!de->d_ino)
41 		return 0;
42 	return !memcmp(name, de->d_name, len);
43 }
44 
45 static int ufs_commit_chunk(struct page *page, loff_t pos, unsigned len)
46 {
47 	struct address_space *mapping = page->mapping;
48 	struct inode *dir = mapping->host;
49 	int err = 0;
50 
51 	inode_inc_iversion(dir);
52 	block_write_end(NULL, mapping, pos, len, len, page, NULL);
53 	if (pos+len > dir->i_size) {
54 		i_size_write(dir, pos+len);
55 		mark_inode_dirty(dir);
56 	}
57 	if (IS_DIRSYNC(dir))
58 		err = write_one_page(page);
59 	else
60 		unlock_page(page);
61 	return err;
62 }
63 
64 static inline void ufs_put_page(struct page *page)
65 {
66 	kunmap(page);
67 	put_page(page);
68 }
69 
70 ino_t ufs_inode_by_name(struct inode *dir, const struct qstr *qstr)
71 {
72 	ino_t res = 0;
73 	struct ufs_dir_entry *de;
74 	struct page *page;
75 
76 	de = ufs_find_entry(dir, qstr, &page);
77 	if (de) {
78 		res = fs32_to_cpu(dir->i_sb, de->d_ino);
79 		ufs_put_page(page);
80 	}
81 	return res;
82 }
83 
84 
85 /* Releases the page */
86 void ufs_set_link(struct inode *dir, struct ufs_dir_entry *de,
87 		  struct page *page, struct inode *inode,
88 		  bool update_times)
89 {
90 	loff_t pos = page_offset(page) +
91 			(char *) de - (char *) page_address(page);
92 	unsigned len = fs16_to_cpu(dir->i_sb, de->d_reclen);
93 	int err;
94 
95 	lock_page(page);
96 	err = ufs_prepare_chunk(page, pos, len);
97 	BUG_ON(err);
98 
99 	de->d_ino = cpu_to_fs32(dir->i_sb, inode->i_ino);
100 	ufs_set_de_type(dir->i_sb, de, inode->i_mode);
101 
102 	err = ufs_commit_chunk(page, pos, len);
103 	ufs_put_page(page);
104 	if (update_times)
105 		dir->i_mtime = dir->i_ctime = current_time(dir);
106 	mark_inode_dirty(dir);
107 }
108 
109 
110 static bool ufs_check_page(struct page *page)
111 {
112 	struct inode *dir = page->mapping->host;
113 	struct super_block *sb = dir->i_sb;
114 	char *kaddr = page_address(page);
115 	unsigned offs, rec_len;
116 	unsigned limit = PAGE_SIZE;
117 	const unsigned chunk_mask = UFS_SB(sb)->s_uspi->s_dirblksize - 1;
118 	struct ufs_dir_entry *p;
119 	char *error;
120 
121 	if ((dir->i_size >> PAGE_SHIFT) == page->index) {
122 		limit = dir->i_size & ~PAGE_MASK;
123 		if (limit & chunk_mask)
124 			goto Ebadsize;
125 		if (!limit)
126 			goto out;
127 	}
128 	for (offs = 0; offs <= limit - UFS_DIR_REC_LEN(1); offs += rec_len) {
129 		p = (struct ufs_dir_entry *)(kaddr + offs);
130 		rec_len = fs16_to_cpu(sb, p->d_reclen);
131 
132 		if (rec_len < UFS_DIR_REC_LEN(1))
133 			goto Eshort;
134 		if (rec_len & 3)
135 			goto Ealign;
136 		if (rec_len < UFS_DIR_REC_LEN(ufs_get_de_namlen(sb, p)))
137 			goto Enamelen;
138 		if (((offs + rec_len - 1) ^ offs) & ~chunk_mask)
139 			goto Espan;
140 		if (fs32_to_cpu(sb, p->d_ino) > (UFS_SB(sb)->s_uspi->s_ipg *
141 						  UFS_SB(sb)->s_uspi->s_ncg))
142 			goto Einumber;
143 	}
144 	if (offs != limit)
145 		goto Eend;
146 out:
147 	SetPageChecked(page);
148 	return true;
149 
150 	/* Too bad, we had an error */
151 
152 Ebadsize:
153 	ufs_error(sb, "ufs_check_page",
154 		  "size of directory #%lu is not a multiple of chunk size",
155 		  dir->i_ino
156 	);
157 	goto fail;
158 Eshort:
159 	error = "rec_len is smaller than minimal";
160 	goto bad_entry;
161 Ealign:
162 	error = "unaligned directory entry";
163 	goto bad_entry;
164 Enamelen:
165 	error = "rec_len is too small for name_len";
166 	goto bad_entry;
167 Espan:
168 	error = "directory entry across blocks";
169 	goto bad_entry;
170 Einumber:
171 	error = "inode out of bounds";
172 bad_entry:
173 	ufs_error (sb, "ufs_check_page", "bad entry in directory #%lu: %s - "
174 		   "offset=%lu, rec_len=%d, name_len=%d",
175 		   dir->i_ino, error, (page->index<<PAGE_SHIFT)+offs,
176 		   rec_len, ufs_get_de_namlen(sb, p));
177 	goto fail;
178 Eend:
179 	p = (struct ufs_dir_entry *)(kaddr + offs);
180 	ufs_error(sb, __func__,
181 		   "entry in directory #%lu spans the page boundary"
182 		   "offset=%lu",
183 		   dir->i_ino, (page->index<<PAGE_SHIFT)+offs);
184 fail:
185 	SetPageError(page);
186 	return false;
187 }
188 
189 static struct page *ufs_get_page(struct inode *dir, unsigned long n)
190 {
191 	struct address_space *mapping = dir->i_mapping;
192 	struct page *page = read_mapping_page(mapping, n, NULL);
193 	if (!IS_ERR(page)) {
194 		kmap(page);
195 		if (unlikely(!PageChecked(page))) {
196 			if (PageError(page) || !ufs_check_page(page))
197 				goto fail;
198 		}
199 	}
200 	return page;
201 
202 fail:
203 	ufs_put_page(page);
204 	return ERR_PTR(-EIO);
205 }
206 
207 /*
208  * Return the offset into page `page_nr' of the last valid
209  * byte in that page, plus one.
210  */
211 static unsigned
212 ufs_last_byte(struct inode *inode, unsigned long page_nr)
213 {
214 	unsigned last_byte = inode->i_size;
215 
216 	last_byte -= page_nr << PAGE_SHIFT;
217 	if (last_byte > PAGE_SIZE)
218 		last_byte = PAGE_SIZE;
219 	return last_byte;
220 }
221 
222 static inline struct ufs_dir_entry *
223 ufs_next_entry(struct super_block *sb, struct ufs_dir_entry *p)
224 {
225 	return (struct ufs_dir_entry *)((char *)p +
226 					fs16_to_cpu(sb, p->d_reclen));
227 }
228 
229 struct ufs_dir_entry *ufs_dotdot(struct inode *dir, struct page **p)
230 {
231 	struct page *page = ufs_get_page(dir, 0);
232 	struct ufs_dir_entry *de = NULL;
233 
234 	if (!IS_ERR(page)) {
235 		de = ufs_next_entry(dir->i_sb,
236 				    (struct ufs_dir_entry *)page_address(page));
237 		*p = page;
238 	}
239 	return de;
240 }
241 
242 /*
243  *	ufs_find_entry()
244  *
245  * finds an entry in the specified directory with the wanted name. It
246  * returns the page in which the entry was found, and the entry itself
247  * (as a parameter - res_dir). Page is returned mapped and unlocked.
248  * Entry is guaranteed to be valid.
249  */
250 struct ufs_dir_entry *ufs_find_entry(struct inode *dir, const struct qstr *qstr,
251 				     struct page **res_page)
252 {
253 	struct super_block *sb = dir->i_sb;
254 	const unsigned char *name = qstr->name;
255 	int namelen = qstr->len;
256 	unsigned reclen = UFS_DIR_REC_LEN(namelen);
257 	unsigned long start, n;
258 	unsigned long npages = dir_pages(dir);
259 	struct page *page = NULL;
260 	struct ufs_inode_info *ui = UFS_I(dir);
261 	struct ufs_dir_entry *de;
262 
263 	UFSD("ENTER, dir_ino %lu, name %s, namlen %u\n", dir->i_ino, name, namelen);
264 
265 	if (npages == 0 || namelen > UFS_MAXNAMLEN)
266 		goto out;
267 
268 	/* OFFSET_CACHE */
269 	*res_page = NULL;
270 
271 	start = ui->i_dir_start_lookup;
272 
273 	if (start >= npages)
274 		start = 0;
275 	n = start;
276 	do {
277 		char *kaddr;
278 		page = ufs_get_page(dir, n);
279 		if (!IS_ERR(page)) {
280 			kaddr = page_address(page);
281 			de = (struct ufs_dir_entry *) kaddr;
282 			kaddr += ufs_last_byte(dir, n) - reclen;
283 			while ((char *) de <= kaddr) {
284 				if (ufs_match(sb, namelen, name, de))
285 					goto found;
286 				de = ufs_next_entry(sb, de);
287 			}
288 			ufs_put_page(page);
289 		}
290 		if (++n >= npages)
291 			n = 0;
292 	} while (n != start);
293 out:
294 	return NULL;
295 
296 found:
297 	*res_page = page;
298 	ui->i_dir_start_lookup = n;
299 	return de;
300 }
301 
302 /*
303  *	Parent is locked.
304  */
305 int ufs_add_link(struct dentry *dentry, struct inode *inode)
306 {
307 	struct inode *dir = d_inode(dentry->d_parent);
308 	const unsigned char *name = dentry->d_name.name;
309 	int namelen = dentry->d_name.len;
310 	struct super_block *sb = dir->i_sb;
311 	unsigned reclen = UFS_DIR_REC_LEN(namelen);
312 	const unsigned int chunk_size = UFS_SB(sb)->s_uspi->s_dirblksize;
313 	unsigned short rec_len, name_len;
314 	struct page *page = NULL;
315 	struct ufs_dir_entry *de;
316 	unsigned long npages = dir_pages(dir);
317 	unsigned long n;
318 	char *kaddr;
319 	loff_t pos;
320 	int err;
321 
322 	UFSD("ENTER, name %s, namelen %u\n", name, namelen);
323 
324 	/*
325 	 * We take care of directory expansion in the same loop.
326 	 * This code plays outside i_size, so it locks the page
327 	 * to protect that region.
328 	 */
329 	for (n = 0; n <= npages; n++) {
330 		char *dir_end;
331 
332 		page = ufs_get_page(dir, n);
333 		err = PTR_ERR(page);
334 		if (IS_ERR(page))
335 			goto out;
336 		lock_page(page);
337 		kaddr = page_address(page);
338 		dir_end = kaddr + ufs_last_byte(dir, n);
339 		de = (struct ufs_dir_entry *)kaddr;
340 		kaddr += PAGE_SIZE - reclen;
341 		while ((char *)de <= kaddr) {
342 			if ((char *)de == dir_end) {
343 				/* We hit i_size */
344 				name_len = 0;
345 				rec_len = chunk_size;
346 				de->d_reclen = cpu_to_fs16(sb, chunk_size);
347 				de->d_ino = 0;
348 				goto got_it;
349 			}
350 			if (de->d_reclen == 0) {
351 				ufs_error(dir->i_sb, __func__,
352 					  "zero-length directory entry");
353 				err = -EIO;
354 				goto out_unlock;
355 			}
356 			err = -EEXIST;
357 			if (ufs_match(sb, namelen, name, de))
358 				goto out_unlock;
359 			name_len = UFS_DIR_REC_LEN(ufs_get_de_namlen(sb, de));
360 			rec_len = fs16_to_cpu(sb, de->d_reclen);
361 			if (!de->d_ino && rec_len >= reclen)
362 				goto got_it;
363 			if (rec_len >= name_len + reclen)
364 				goto got_it;
365 			de = (struct ufs_dir_entry *) ((char *) de + rec_len);
366 		}
367 		unlock_page(page);
368 		ufs_put_page(page);
369 	}
370 	BUG();
371 	return -EINVAL;
372 
373 got_it:
374 	pos = page_offset(page) +
375 			(char*)de - (char*)page_address(page);
376 	err = ufs_prepare_chunk(page, pos, rec_len);
377 	if (err)
378 		goto out_unlock;
379 	if (de->d_ino) {
380 		struct ufs_dir_entry *de1 =
381 			(struct ufs_dir_entry *) ((char *) de + name_len);
382 		de1->d_reclen = cpu_to_fs16(sb, rec_len - name_len);
383 		de->d_reclen = cpu_to_fs16(sb, name_len);
384 
385 		de = de1;
386 	}
387 
388 	ufs_set_de_namlen(sb, de, namelen);
389 	memcpy(de->d_name, name, namelen + 1);
390 	de->d_ino = cpu_to_fs32(sb, inode->i_ino);
391 	ufs_set_de_type(sb, de, inode->i_mode);
392 
393 	err = ufs_commit_chunk(page, pos, rec_len);
394 	dir->i_mtime = dir->i_ctime = current_time(dir);
395 
396 	mark_inode_dirty(dir);
397 	/* OFFSET_CACHE */
398 out_put:
399 	ufs_put_page(page);
400 out:
401 	return err;
402 out_unlock:
403 	unlock_page(page);
404 	goto out_put;
405 }
406 
407 static inline unsigned
408 ufs_validate_entry(struct super_block *sb, char *base,
409 		   unsigned offset, unsigned mask)
410 {
411 	struct ufs_dir_entry *de = (struct ufs_dir_entry*)(base + offset);
412 	struct ufs_dir_entry *p = (struct ufs_dir_entry*)(base + (offset&mask));
413 	while ((char*)p < (char*)de)
414 		p = ufs_next_entry(sb, p);
415 	return (char *)p - base;
416 }
417 
418 
419 /*
420  * This is blatantly stolen from ext2fs
421  */
422 static int
423 ufs_readdir(struct file *file, struct dir_context *ctx)
424 {
425 	loff_t pos = ctx->pos;
426 	struct inode *inode = file_inode(file);
427 	struct super_block *sb = inode->i_sb;
428 	unsigned int offset = pos & ~PAGE_MASK;
429 	unsigned long n = pos >> PAGE_SHIFT;
430 	unsigned long npages = dir_pages(inode);
431 	unsigned chunk_mask = ~(UFS_SB(sb)->s_uspi->s_dirblksize - 1);
432 	bool need_revalidate = !inode_eq_iversion(inode, file->f_version);
433 	unsigned flags = UFS_SB(sb)->s_flags;
434 
435 	UFSD("BEGIN\n");
436 
437 	if (pos > inode->i_size - UFS_DIR_REC_LEN(1))
438 		return 0;
439 
440 	for ( ; n < npages; n++, offset = 0) {
441 		char *kaddr, *limit;
442 		struct ufs_dir_entry *de;
443 
444 		struct page *page = ufs_get_page(inode, n);
445 
446 		if (IS_ERR(page)) {
447 			ufs_error(sb, __func__,
448 				  "bad page in #%lu",
449 				  inode->i_ino);
450 			ctx->pos += PAGE_SIZE - offset;
451 			return -EIO;
452 		}
453 		kaddr = page_address(page);
454 		if (unlikely(need_revalidate)) {
455 			if (offset) {
456 				offset = ufs_validate_entry(sb, kaddr, offset, chunk_mask);
457 				ctx->pos = (n<<PAGE_SHIFT) + offset;
458 			}
459 			file->f_version = inode_query_iversion(inode);
460 			need_revalidate = false;
461 		}
462 		de = (struct ufs_dir_entry *)(kaddr+offset);
463 		limit = kaddr + ufs_last_byte(inode, n) - UFS_DIR_REC_LEN(1);
464 		for ( ;(char*)de <= limit; de = ufs_next_entry(sb, de)) {
465 			if (de->d_ino) {
466 				unsigned char d_type = DT_UNKNOWN;
467 
468 				UFSD("filldir(%s,%u)\n", de->d_name,
469 				      fs32_to_cpu(sb, de->d_ino));
470 				UFSD("namlen %u\n", ufs_get_de_namlen(sb, de));
471 
472 				if ((flags & UFS_DE_MASK) == UFS_DE_44BSD)
473 					d_type = de->d_u.d_44.d_type;
474 
475 				if (!dir_emit(ctx, de->d_name,
476 					       ufs_get_de_namlen(sb, de),
477 					       fs32_to_cpu(sb, de->d_ino),
478 					       d_type)) {
479 					ufs_put_page(page);
480 					return 0;
481 				}
482 			}
483 			ctx->pos += fs16_to_cpu(sb, de->d_reclen);
484 		}
485 		ufs_put_page(page);
486 	}
487 	return 0;
488 }
489 
490 
491 /*
492  * ufs_delete_entry deletes a directory entry by merging it with the
493  * previous entry.
494  */
495 int ufs_delete_entry(struct inode *inode, struct ufs_dir_entry *dir,
496 		     struct page * page)
497 {
498 	struct super_block *sb = inode->i_sb;
499 	char *kaddr = page_address(page);
500 	unsigned from = ((char*)dir - kaddr) & ~(UFS_SB(sb)->s_uspi->s_dirblksize - 1);
501 	unsigned to = ((char*)dir - kaddr) + fs16_to_cpu(sb, dir->d_reclen);
502 	loff_t pos;
503 	struct ufs_dir_entry *pde = NULL;
504 	struct ufs_dir_entry *de = (struct ufs_dir_entry *) (kaddr + from);
505 	int err;
506 
507 	UFSD("ENTER\n");
508 
509 	UFSD("ino %u, reclen %u, namlen %u, name %s\n",
510 	      fs32_to_cpu(sb, de->d_ino),
511 	      fs16_to_cpu(sb, de->d_reclen),
512 	      ufs_get_de_namlen(sb, de), de->d_name);
513 
514 	while ((char*)de < (char*)dir) {
515 		if (de->d_reclen == 0) {
516 			ufs_error(inode->i_sb, __func__,
517 				  "zero-length directory entry");
518 			err = -EIO;
519 			goto out;
520 		}
521 		pde = de;
522 		de = ufs_next_entry(sb, de);
523 	}
524 	if (pde)
525 		from = (char*)pde - (char*)page_address(page);
526 
527 	pos = page_offset(page) + from;
528 	lock_page(page);
529 	err = ufs_prepare_chunk(page, pos, to - from);
530 	BUG_ON(err);
531 	if (pde)
532 		pde->d_reclen = cpu_to_fs16(sb, to - from);
533 	dir->d_ino = 0;
534 	err = ufs_commit_chunk(page, pos, to - from);
535 	inode->i_ctime = inode->i_mtime = current_time(inode);
536 	mark_inode_dirty(inode);
537 out:
538 	ufs_put_page(page);
539 	UFSD("EXIT\n");
540 	return err;
541 }
542 
543 int ufs_make_empty(struct inode * inode, struct inode *dir)
544 {
545 	struct super_block * sb = dir->i_sb;
546 	struct address_space *mapping = inode->i_mapping;
547 	struct page *page = grab_cache_page(mapping, 0);
548 	const unsigned int chunk_size = UFS_SB(sb)->s_uspi->s_dirblksize;
549 	struct ufs_dir_entry * de;
550 	char *base;
551 	int err;
552 
553 	if (!page)
554 		return -ENOMEM;
555 
556 	err = ufs_prepare_chunk(page, 0, chunk_size);
557 	if (err) {
558 		unlock_page(page);
559 		goto fail;
560 	}
561 
562 	kmap(page);
563 	base = (char*)page_address(page);
564 	memset(base, 0, PAGE_SIZE);
565 
566 	de = (struct ufs_dir_entry *) base;
567 
568 	de->d_ino = cpu_to_fs32(sb, inode->i_ino);
569 	ufs_set_de_type(sb, de, inode->i_mode);
570 	ufs_set_de_namlen(sb, de, 1);
571 	de->d_reclen = cpu_to_fs16(sb, UFS_DIR_REC_LEN(1));
572 	strcpy (de->d_name, ".");
573 	de = (struct ufs_dir_entry *)
574 		((char *)de + fs16_to_cpu(sb, de->d_reclen));
575 	de->d_ino = cpu_to_fs32(sb, dir->i_ino);
576 	ufs_set_de_type(sb, de, dir->i_mode);
577 	de->d_reclen = cpu_to_fs16(sb, chunk_size - UFS_DIR_REC_LEN(1));
578 	ufs_set_de_namlen(sb, de, 2);
579 	strcpy (de->d_name, "..");
580 	kunmap(page);
581 
582 	err = ufs_commit_chunk(page, 0, chunk_size);
583 fail:
584 	put_page(page);
585 	return err;
586 }
587 
588 /*
589  * routine to check that the specified directory is empty (for rmdir)
590  */
591 int ufs_empty_dir(struct inode * inode)
592 {
593 	struct super_block *sb = inode->i_sb;
594 	struct page *page = NULL;
595 	unsigned long i, npages = dir_pages(inode);
596 
597 	for (i = 0; i < npages; i++) {
598 		char *kaddr;
599 		struct ufs_dir_entry *de;
600 		page = ufs_get_page(inode, i);
601 
602 		if (IS_ERR(page))
603 			continue;
604 
605 		kaddr = page_address(page);
606 		de = (struct ufs_dir_entry *)kaddr;
607 		kaddr += ufs_last_byte(inode, i) - UFS_DIR_REC_LEN(1);
608 
609 		while ((char *)de <= kaddr) {
610 			if (de->d_reclen == 0) {
611 				ufs_error(inode->i_sb, __func__,
612 					"zero-length directory entry: "
613 					"kaddr=%p, de=%p\n", kaddr, de);
614 				goto not_empty;
615 			}
616 			if (de->d_ino) {
617 				u16 namelen=ufs_get_de_namlen(sb, de);
618 				/* check for . and .. */
619 				if (de->d_name[0] != '.')
620 					goto not_empty;
621 				if (namelen > 2)
622 					goto not_empty;
623 				if (namelen < 2) {
624 					if (inode->i_ino !=
625 					    fs32_to_cpu(sb, de->d_ino))
626 						goto not_empty;
627 				} else if (de->d_name[1] != '.')
628 					goto not_empty;
629 			}
630 			de = ufs_next_entry(sb, de);
631 		}
632 		ufs_put_page(page);
633 	}
634 	return 1;
635 
636 not_empty:
637 	ufs_put_page(page);
638 	return 0;
639 }
640 
641 const struct file_operations ufs_dir_operations = {
642 	.read		= generic_read_dir,
643 	.iterate_shared	= ufs_readdir,
644 	.fsync		= generic_file_fsync,
645 	.llseek		= generic_file_llseek,
646 };
647