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 */
35static 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
45static void 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
50	inode_inc_iversion(dir);
51	block_write_end(NULL, mapping, pos, len, len, page, NULL);
52	if (pos+len > dir->i_size) {
53		i_size_write(dir, pos+len);
54		mark_inode_dirty(dir);
55	}
56	unlock_page(page);
57}
58
59static int ufs_handle_dirsync(struct inode *dir)
60{
61	int err;
62
63	err = filemap_write_and_wait(dir->i_mapping);
64	if (!err)
65		err = sync_inode_metadata(dir, 1);
66	return err;
67}
68
69static inline void ufs_put_page(struct page *page)
70{
71	kunmap(page);
72	put_page(page);
73}
74
75ino_t ufs_inode_by_name(struct inode *dir, const struct qstr *qstr)
76{
77	ino_t res = 0;
78	struct ufs_dir_entry *de;
79	struct page *page;
80
81	de = ufs_find_entry(dir, qstr, &page);
82	if (de) {
83		res = fs32_to_cpu(dir->i_sb, de->d_ino);
84		ufs_put_page(page);
85	}
86	return res;
87}
88
89
90/* Releases the page */
91void ufs_set_link(struct inode *dir, struct ufs_dir_entry *de,
92		  struct page *page, struct inode *inode,
93		  bool update_times)
94{
95	loff_t pos = page_offset(page) +
96			(char *) de - (char *) page_address(page);
97	unsigned len = fs16_to_cpu(dir->i_sb, de->d_reclen);
98	int err;
99
100	lock_page(page);
101	err = ufs_prepare_chunk(page, pos, len);
102	BUG_ON(err);
103
104	de->d_ino = cpu_to_fs32(dir->i_sb, inode->i_ino);
105	ufs_set_de_type(dir->i_sb, de, inode->i_mode);
106
107	ufs_commit_chunk(page, pos, len);
108	ufs_put_page(page);
109	if (update_times)
110		inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir));
111	mark_inode_dirty(dir);
112	ufs_handle_dirsync(dir);
113}
114
115
116static bool ufs_check_page(struct page *page)
117{
118	struct inode *dir = page->mapping->host;
119	struct super_block *sb = dir->i_sb;
120	char *kaddr = page_address(page);
121	unsigned offs, rec_len;
122	unsigned limit = PAGE_SIZE;
123	const unsigned chunk_mask = UFS_SB(sb)->s_uspi->s_dirblksize - 1;
124	struct ufs_dir_entry *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_mask)
130			goto Ebadsize;
131		if (!limit)
132			goto out;
133	}
134	for (offs = 0; offs <= limit - UFS_DIR_REC_LEN(1); offs += rec_len) {
135		p = (struct ufs_dir_entry *)(kaddr + offs);
136		rec_len = fs16_to_cpu(sb, p->d_reclen);
137
138		if (rec_len < UFS_DIR_REC_LEN(1))
139			goto Eshort;
140		if (rec_len & 3)
141			goto Ealign;
142		if (rec_len < UFS_DIR_REC_LEN(ufs_get_de_namlen(sb, p)))
143			goto Enamelen;
144		if (((offs + rec_len - 1) ^ offs) & ~chunk_mask)
145			goto Espan;
146		if (fs32_to_cpu(sb, p->d_ino) > (UFS_SB(sb)->s_uspi->s_ipg *
147						  UFS_SB(sb)->s_uspi->s_ncg))
148			goto Einumber;
149	}
150	if (offs != limit)
151		goto Eend;
152out:
153	SetPageChecked(page);
154	return true;
155
156	/* Too bad, we had an error */
157
158Ebadsize:
159	ufs_error(sb, "ufs_check_page",
160		  "size of directory #%lu is not a multiple of chunk size",
161		  dir->i_ino
162	);
163	goto fail;
164Eshort:
165	error = "rec_len is smaller than minimal";
166	goto bad_entry;
167Ealign:
168	error = "unaligned directory entry";
169	goto bad_entry;
170Enamelen:
171	error = "rec_len is too small for name_len";
172	goto bad_entry;
173Espan:
174	error = "directory entry across blocks";
175	goto bad_entry;
176Einumber:
177	error = "inode out of bounds";
178bad_entry:
179	ufs_error (sb, "ufs_check_page", "bad entry in directory #%lu: %s - "
180		   "offset=%lu, rec_len=%d, name_len=%d",
181		   dir->i_ino, error, (page->index<<PAGE_SHIFT)+offs,
182		   rec_len, ufs_get_de_namlen(sb, p));
183	goto fail;
184Eend:
185	p = (struct ufs_dir_entry *)(kaddr + offs);
186	ufs_error(sb, __func__,
187		   "entry in directory #%lu spans the page boundary"
188		   "offset=%lu",
189		   dir->i_ino, (page->index<<PAGE_SHIFT)+offs);
190fail:
191	SetPageError(page);
192	return false;
193}
194
195static struct page *ufs_get_page(struct inode *dir, unsigned long n)
196{
197	struct address_space *mapping = dir->i_mapping;
198	struct page *page = read_mapping_page(mapping, n, NULL);
199	if (!IS_ERR(page)) {
200		kmap(page);
201		if (unlikely(!PageChecked(page))) {
202			if (!ufs_check_page(page))
203				goto fail;
204		}
205	}
206	return page;
207
208fail:
209	ufs_put_page(page);
210	return ERR_PTR(-EIO);
211}
212
213/*
214 * Return the offset into page `page_nr' of the last valid
215 * byte in that page, plus one.
216 */
217static unsigned
218ufs_last_byte(struct inode *inode, unsigned long page_nr)
219{
220	unsigned last_byte = inode->i_size;
221
222	last_byte -= page_nr << PAGE_SHIFT;
223	if (last_byte > PAGE_SIZE)
224		last_byte = PAGE_SIZE;
225	return last_byte;
226}
227
228static inline struct ufs_dir_entry *
229ufs_next_entry(struct super_block *sb, struct ufs_dir_entry *p)
230{
231	return (struct ufs_dir_entry *)((char *)p +
232					fs16_to_cpu(sb, p->d_reclen));
233}
234
235struct ufs_dir_entry *ufs_dotdot(struct inode *dir, struct page **p)
236{
237	struct page *page = ufs_get_page(dir, 0);
238	struct ufs_dir_entry *de = NULL;
239
240	if (!IS_ERR(page)) {
241		de = ufs_next_entry(dir->i_sb,
242				    (struct ufs_dir_entry *)page_address(page));
243		*p = page;
244	}
245	return de;
246}
247
248/*
249 *	ufs_find_entry()
250 *
251 * finds an entry in the specified directory with the wanted name. It
252 * returns the page in which the entry was found, and the entry itself
253 * (as a parameter - res_dir). Page is returned mapped and unlocked.
254 * Entry is guaranteed to be valid.
255 */
256struct ufs_dir_entry *ufs_find_entry(struct inode *dir, const struct qstr *qstr,
257				     struct page **res_page)
258{
259	struct super_block *sb = dir->i_sb;
260	const unsigned char *name = qstr->name;
261	int namelen = qstr->len;
262	unsigned reclen = UFS_DIR_REC_LEN(namelen);
263	unsigned long start, n;
264	unsigned long npages = dir_pages(dir);
265	struct page *page = NULL;
266	struct ufs_inode_info *ui = UFS_I(dir);
267	struct ufs_dir_entry *de;
268
269	UFSD("ENTER, dir_ino %lu, name %s, namlen %u\n", dir->i_ino, name, namelen);
270
271	if (npages == 0 || namelen > UFS_MAXNAMLEN)
272		goto out;
273
274	/* OFFSET_CACHE */
275	*res_page = NULL;
276
277	start = ui->i_dir_start_lookup;
278
279	if (start >= npages)
280		start = 0;
281	n = start;
282	do {
283		char *kaddr;
284		page = ufs_get_page(dir, n);
285		if (!IS_ERR(page)) {
286			kaddr = page_address(page);
287			de = (struct ufs_dir_entry *) kaddr;
288			kaddr += ufs_last_byte(dir, n) - reclen;
289			while ((char *) de <= kaddr) {
290				if (ufs_match(sb, namelen, name, de))
291					goto found;
292				de = ufs_next_entry(sb, de);
293			}
294			ufs_put_page(page);
295		}
296		if (++n >= npages)
297			n = 0;
298	} while (n != start);
299out:
300	return NULL;
301
302found:
303	*res_page = page;
304	ui->i_dir_start_lookup = n;
305	return de;
306}
307
308/*
309 *	Parent is locked.
310 */
311int ufs_add_link(struct dentry *dentry, struct inode *inode)
312{
313	struct inode *dir = d_inode(dentry->d_parent);
314	const unsigned char *name = dentry->d_name.name;
315	int namelen = dentry->d_name.len;
316	struct super_block *sb = dir->i_sb;
317	unsigned reclen = UFS_DIR_REC_LEN(namelen);
318	const unsigned int chunk_size = UFS_SB(sb)->s_uspi->s_dirblksize;
319	unsigned short rec_len, name_len;
320	struct page *page = NULL;
321	struct ufs_dir_entry *de;
322	unsigned long npages = dir_pages(dir);
323	unsigned long n;
324	char *kaddr;
325	loff_t pos;
326	int err;
327
328	UFSD("ENTER, name %s, namelen %u\n", name, namelen);
329
330	/*
331	 * We take care of directory expansion in the same loop.
332	 * This code plays outside i_size, so it locks the page
333	 * to protect that region.
334	 */
335	for (n = 0; n <= npages; n++) {
336		char *dir_end;
337
338		page = ufs_get_page(dir, n);
339		err = PTR_ERR(page);
340		if (IS_ERR(page))
341			goto out;
342		lock_page(page);
343		kaddr = page_address(page);
344		dir_end = kaddr + ufs_last_byte(dir, n);
345		de = (struct ufs_dir_entry *)kaddr;
346		kaddr += PAGE_SIZE - reclen;
347		while ((char *)de <= kaddr) {
348			if ((char *)de == dir_end) {
349				/* We hit i_size */
350				name_len = 0;
351				rec_len = chunk_size;
352				de->d_reclen = cpu_to_fs16(sb, chunk_size);
353				de->d_ino = 0;
354				goto got_it;
355			}
356			if (de->d_reclen == 0) {
357				ufs_error(dir->i_sb, __func__,
358					  "zero-length directory entry");
359				err = -EIO;
360				goto out_unlock;
361			}
362			err = -EEXIST;
363			if (ufs_match(sb, namelen, name, de))
364				goto out_unlock;
365			name_len = UFS_DIR_REC_LEN(ufs_get_de_namlen(sb, de));
366			rec_len = fs16_to_cpu(sb, de->d_reclen);
367			if (!de->d_ino && rec_len >= reclen)
368				goto got_it;
369			if (rec_len >= name_len + reclen)
370				goto got_it;
371			de = (struct ufs_dir_entry *) ((char *) de + rec_len);
372		}
373		unlock_page(page);
374		ufs_put_page(page);
375	}
376	BUG();
377	return -EINVAL;
378
379got_it:
380	pos = page_offset(page) +
381			(char*)de - (char*)page_address(page);
382	err = ufs_prepare_chunk(page, pos, rec_len);
383	if (err)
384		goto out_unlock;
385	if (de->d_ino) {
386		struct ufs_dir_entry *de1 =
387			(struct ufs_dir_entry *) ((char *) de + name_len);
388		de1->d_reclen = cpu_to_fs16(sb, rec_len - name_len);
389		de->d_reclen = cpu_to_fs16(sb, name_len);
390
391		de = de1;
392	}
393
394	ufs_set_de_namlen(sb, de, namelen);
395	memcpy(de->d_name, name, namelen + 1);
396	de->d_ino = cpu_to_fs32(sb, inode->i_ino);
397	ufs_set_de_type(sb, de, inode->i_mode);
398
399	ufs_commit_chunk(page, pos, rec_len);
400	inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir));
401
402	mark_inode_dirty(dir);
403	err = ufs_handle_dirsync(dir);
404	/* OFFSET_CACHE */
405out_put:
406	ufs_put_page(page);
407out:
408	return err;
409out_unlock:
410	unlock_page(page);
411	goto out_put;
412}
413
414static inline unsigned
415ufs_validate_entry(struct super_block *sb, char *base,
416		   unsigned offset, unsigned mask)
417{
418	struct ufs_dir_entry *de = (struct ufs_dir_entry*)(base + offset);
419	struct ufs_dir_entry *p = (struct ufs_dir_entry*)(base + (offset&mask));
420	while ((char*)p < (char*)de)
421		p = ufs_next_entry(sb, p);
422	return (char *)p - base;
423}
424
425
426/*
427 * This is blatantly stolen from ext2fs
428 */
429static int
430ufs_readdir(struct file *file, struct dir_context *ctx)
431{
432	loff_t pos = ctx->pos;
433	struct inode *inode = file_inode(file);
434	struct super_block *sb = inode->i_sb;
435	unsigned int offset = pos & ~PAGE_MASK;
436	unsigned long n = pos >> PAGE_SHIFT;
437	unsigned long npages = dir_pages(inode);
438	unsigned chunk_mask = ~(UFS_SB(sb)->s_uspi->s_dirblksize - 1);
439	bool need_revalidate = !inode_eq_iversion(inode, file->f_version);
440	unsigned flags = UFS_SB(sb)->s_flags;
441
442	UFSD("BEGIN\n");
443
444	if (pos > inode->i_size - UFS_DIR_REC_LEN(1))
445		return 0;
446
447	for ( ; n < npages; n++, offset = 0) {
448		char *kaddr, *limit;
449		struct ufs_dir_entry *de;
450
451		struct page *page = ufs_get_page(inode, n);
452
453		if (IS_ERR(page)) {
454			ufs_error(sb, __func__,
455				  "bad page in #%lu",
456				  inode->i_ino);
457			ctx->pos += PAGE_SIZE - offset;
458			return -EIO;
459		}
460		kaddr = page_address(page);
461		if (unlikely(need_revalidate)) {
462			if (offset) {
463				offset = ufs_validate_entry(sb, kaddr, offset, chunk_mask);
464				ctx->pos = (n<<PAGE_SHIFT) + offset;
465			}
466			file->f_version = inode_query_iversion(inode);
467			need_revalidate = false;
468		}
469		de = (struct ufs_dir_entry *)(kaddr+offset);
470		limit = kaddr + ufs_last_byte(inode, n) - UFS_DIR_REC_LEN(1);
471		for ( ;(char*)de <= limit; de = ufs_next_entry(sb, de)) {
472			if (de->d_ino) {
473				unsigned char d_type = DT_UNKNOWN;
474
475				UFSD("filldir(%s,%u)\n", de->d_name,
476				      fs32_to_cpu(sb, de->d_ino));
477				UFSD("namlen %u\n", ufs_get_de_namlen(sb, de));
478
479				if ((flags & UFS_DE_MASK) == UFS_DE_44BSD)
480					d_type = de->d_u.d_44.d_type;
481
482				if (!dir_emit(ctx, de->d_name,
483					       ufs_get_de_namlen(sb, de),
484					       fs32_to_cpu(sb, de->d_ino),
485					       d_type)) {
486					ufs_put_page(page);
487					return 0;
488				}
489			}
490			ctx->pos += fs16_to_cpu(sb, de->d_reclen);
491		}
492		ufs_put_page(page);
493	}
494	return 0;
495}
496
497
498/*
499 * ufs_delete_entry deletes a directory entry by merging it with the
500 * previous entry.
501 */
502int ufs_delete_entry(struct inode *inode, struct ufs_dir_entry *dir,
503		     struct page * page)
504{
505	struct super_block *sb = inode->i_sb;
506	char *kaddr = page_address(page);
507	unsigned from = ((char*)dir - kaddr) & ~(UFS_SB(sb)->s_uspi->s_dirblksize - 1);
508	unsigned to = ((char*)dir - kaddr) + fs16_to_cpu(sb, dir->d_reclen);
509	loff_t pos;
510	struct ufs_dir_entry *pde = NULL;
511	struct ufs_dir_entry *de = (struct ufs_dir_entry *) (kaddr + from);
512	int err;
513
514	UFSD("ENTER\n");
515
516	UFSD("ino %u, reclen %u, namlen %u, name %s\n",
517	      fs32_to_cpu(sb, de->d_ino),
518	      fs16_to_cpu(sb, de->d_reclen),
519	      ufs_get_de_namlen(sb, de), de->d_name);
520
521	while ((char*)de < (char*)dir) {
522		if (de->d_reclen == 0) {
523			ufs_error(inode->i_sb, __func__,
524				  "zero-length directory entry");
525			err = -EIO;
526			goto out;
527		}
528		pde = de;
529		de = ufs_next_entry(sb, de);
530	}
531	if (pde)
532		from = (char*)pde - (char*)page_address(page);
533
534	pos = page_offset(page) + from;
535	lock_page(page);
536	err = ufs_prepare_chunk(page, pos, to - from);
537	BUG_ON(err);
538	if (pde)
539		pde->d_reclen = cpu_to_fs16(sb, to - from);
540	dir->d_ino = 0;
541	ufs_commit_chunk(page, pos, to - from);
542	inode_set_mtime_to_ts(inode, inode_set_ctime_current(inode));
543	mark_inode_dirty(inode);
544	err = ufs_handle_dirsync(inode);
545out:
546	ufs_put_page(page);
547	UFSD("EXIT\n");
548	return err;
549}
550
551int ufs_make_empty(struct inode * inode, struct inode *dir)
552{
553	struct super_block * sb = dir->i_sb;
554	struct address_space *mapping = inode->i_mapping;
555	struct page *page = grab_cache_page(mapping, 0);
556	const unsigned int chunk_size = UFS_SB(sb)->s_uspi->s_dirblksize;
557	struct ufs_dir_entry * de;
558	char *base;
559	int err;
560
561	if (!page)
562		return -ENOMEM;
563
564	err = ufs_prepare_chunk(page, 0, chunk_size);
565	if (err) {
566		unlock_page(page);
567		goto fail;
568	}
569
570	kmap(page);
571	base = (char*)page_address(page);
572	memset(base, 0, PAGE_SIZE);
573
574	de = (struct ufs_dir_entry *) base;
575
576	de->d_ino = cpu_to_fs32(sb, inode->i_ino);
577	ufs_set_de_type(sb, de, inode->i_mode);
578	ufs_set_de_namlen(sb, de, 1);
579	de->d_reclen = cpu_to_fs16(sb, UFS_DIR_REC_LEN(1));
580	strcpy (de->d_name, ".");
581	de = (struct ufs_dir_entry *)
582		((char *)de + fs16_to_cpu(sb, de->d_reclen));
583	de->d_ino = cpu_to_fs32(sb, dir->i_ino);
584	ufs_set_de_type(sb, de, dir->i_mode);
585	de->d_reclen = cpu_to_fs16(sb, chunk_size - UFS_DIR_REC_LEN(1));
586	ufs_set_de_namlen(sb, de, 2);
587	strcpy (de->d_name, "..");
588	kunmap(page);
589
590	ufs_commit_chunk(page, 0, chunk_size);
591	err = ufs_handle_dirsync(inode);
592fail:
593	put_page(page);
594	return err;
595}
596
597/*
598 * routine to check that the specified directory is empty (for rmdir)
599 */
600int ufs_empty_dir(struct inode * inode)
601{
602	struct super_block *sb = inode->i_sb;
603	struct page *page = NULL;
604	unsigned long i, npages = dir_pages(inode);
605
606	for (i = 0; i < npages; i++) {
607		char *kaddr;
608		struct ufs_dir_entry *de;
609		page = ufs_get_page(inode, i);
610
611		if (IS_ERR(page))
612			continue;
613
614		kaddr = page_address(page);
615		de = (struct ufs_dir_entry *)kaddr;
616		kaddr += ufs_last_byte(inode, i) - UFS_DIR_REC_LEN(1);
617
618		while ((char *)de <= kaddr) {
619			if (de->d_reclen == 0) {
620				ufs_error(inode->i_sb, __func__,
621					"zero-length directory entry: "
622					"kaddr=%p, de=%p\n", kaddr, de);
623				goto not_empty;
624			}
625			if (de->d_ino) {
626				u16 namelen=ufs_get_de_namlen(sb, de);
627				/* check for . and .. */
628				if (de->d_name[0] != '.')
629					goto not_empty;
630				if (namelen > 2)
631					goto not_empty;
632				if (namelen < 2) {
633					if (inode->i_ino !=
634					    fs32_to_cpu(sb, de->d_ino))
635						goto not_empty;
636				} else if (de->d_name[1] != '.')
637					goto not_empty;
638			}
639			de = ufs_next_entry(sb, de);
640		}
641		ufs_put_page(page);
642	}
643	return 1;
644
645not_empty:
646	ufs_put_page(page);
647	return 0;
648}
649
650const struct file_operations ufs_dir_operations = {
651	.read		= generic_read_dir,
652	.iterate_shared	= ufs_readdir,
653	.fsync		= generic_file_fsync,
654	.llseek		= generic_file_llseek,
655};
656