xref: /linux/fs/fat/namei_msdos.c (revision 1cbc822816758b2678e94800ce8eecc7b706fb84)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *  linux/fs/msdos/namei.c
4  *
5  *  Written 1992,1993 by Werner Almesberger
6  *  Hidden files 1995 by Albert Cahalan <albert@ccs.neu.edu> <adc@coe.neu.edu>
7  *  Rewritten for constant inumbers 1999 by Al Viro
8  */
9 
10 #include <linux/module.h>
11 #include <linux/iversion.h>
12 #include "fat.h"
13 
14 /* Characters that are undesirable in an MS-DOS file name */
15 static unsigned char bad_chars[] = "*?<>|\"";
16 static unsigned char bad_if_strict[] = "+=,; ";
17 
18 /***** Formats an MS-DOS file name. Rejects invalid names. */
19 static int msdos_format_name(const unsigned char *name, int len,
20 			     unsigned char *res, struct fat_mount_options *opts)
21 	/*
22 	 * name is the proposed name, len is its length, res is
23 	 * the resulting name, opts->name_check is either (r)elaxed,
24 	 * (n)ormal or (s)trict, opts->dotsOK allows dots at the
25 	 * beginning of name (for hidden files)
26 	 */
27 {
28 	unsigned char *walk;
29 	unsigned char c;
30 	int space;
31 
32 	if (name[0] == '.') {	/* dotfile because . and .. already done */
33 		if (opts->dotsOK) {
34 			/* Get rid of dot - test for it elsewhere */
35 			name++;
36 			len--;
37 		} else
38 			return -EINVAL;
39 	}
40 	/*
41 	 * disallow names that _really_ start with a dot
42 	 */
43 	space = 1;
44 	c = 0;
45 	for (walk = res; len && walk - res < 8; walk++) {
46 		c = *name++;
47 		len--;
48 		if (opts->name_check != 'r' && strchr(bad_chars, c))
49 			return -EINVAL;
50 		if (opts->name_check == 's' && strchr(bad_if_strict, c))
51 			return -EINVAL;
52 		if (c >= 'A' && c <= 'Z' && opts->name_check == 's')
53 			return -EINVAL;
54 		if (c < ' ' || c == ':' || c == '\\')
55 			return -EINVAL;
56 	/*
57 	 * 0xE5 is legal as a first character, but we must substitute
58 	 * 0x05 because 0xE5 marks deleted files.  Yes, DOS really
59 	 * does this.
60 	 * It seems that Microsoft hacked DOS to support non-US
61 	 * characters after the 0xE5 character was already in use to
62 	 * mark deleted files.
63 	 */
64 		if ((res == walk) && (c == 0xE5))
65 			c = 0x05;
66 		if (c == '.')
67 			break;
68 		space = (c == ' ');
69 		*walk = (!opts->nocase && c >= 'a' && c <= 'z') ? c - 32 : c;
70 	}
71 	if (space)
72 		return -EINVAL;
73 	if (opts->name_check == 's' && len && c != '.') {
74 		c = *name++;
75 		len--;
76 		if (c != '.')
77 			return -EINVAL;
78 	}
79 	while (c != '.' && len--)
80 		c = *name++;
81 	if (c == '.') {
82 		while (walk - res < 8)
83 			*walk++ = ' ';
84 		while (len > 0 && walk - res < MSDOS_NAME) {
85 			c = *name++;
86 			len--;
87 			if (opts->name_check != 'r' && strchr(bad_chars, c))
88 				return -EINVAL;
89 			if (opts->name_check == 's' &&
90 			    strchr(bad_if_strict, c))
91 				return -EINVAL;
92 			if (c < ' ' || c == ':' || c == '\\')
93 				return -EINVAL;
94 			if (c == '.') {
95 				if (opts->name_check == 's')
96 					return -EINVAL;
97 				break;
98 			}
99 			if (c >= 'A' && c <= 'Z' && opts->name_check == 's')
100 				return -EINVAL;
101 			space = c == ' ';
102 			if (!opts->nocase && c >= 'a' && c <= 'z')
103 				*walk++ = c - 32;
104 			else
105 				*walk++ = c;
106 		}
107 		if (space)
108 			return -EINVAL;
109 		if (opts->name_check == 's' && len)
110 			return -EINVAL;
111 	}
112 	while (walk - res < MSDOS_NAME)
113 		*walk++ = ' ';
114 
115 	return 0;
116 }
117 
118 /***** Locates a directory entry.  Uses unformatted name. */
119 static int msdos_find(struct inode *dir, const unsigned char *name, int len,
120 		      struct fat_slot_info *sinfo)
121 {
122 	struct msdos_sb_info *sbi = MSDOS_SB(dir->i_sb);
123 	unsigned char msdos_name[MSDOS_NAME];
124 	int err;
125 
126 	err = msdos_format_name(name, len, msdos_name, &sbi->options);
127 	if (err)
128 		return -ENOENT;
129 
130 	err = fat_scan(dir, msdos_name, sinfo);
131 	if (!err && sbi->options.dotsOK) {
132 		if (name[0] == '.') {
133 			if (!(sinfo->de->attr & ATTR_HIDDEN))
134 				err = -ENOENT;
135 		} else {
136 			if (sinfo->de->attr & ATTR_HIDDEN)
137 				err = -ENOENT;
138 		}
139 		if (err)
140 			brelse(sinfo->bh);
141 	}
142 	return err;
143 }
144 
145 /*
146  * Compute the hash for the msdos name corresponding to the dentry.
147  * Note: if the name is invalid, we leave the hash code unchanged so
148  * that the existing dentry can be used. The msdos fs routines will
149  * return ENOENT or EINVAL as appropriate.
150  */
151 static int msdos_hash(const struct dentry *dentry, struct qstr *qstr)
152 {
153 	struct fat_mount_options *options = &MSDOS_SB(dentry->d_sb)->options;
154 	unsigned char msdos_name[MSDOS_NAME];
155 	int error;
156 
157 	error = msdos_format_name(qstr->name, qstr->len, msdos_name, options);
158 	if (!error)
159 		qstr->hash = full_name_hash(dentry, msdos_name, MSDOS_NAME);
160 	return 0;
161 }
162 
163 /*
164  * Compare two msdos names. If either of the names are invalid,
165  * we fall back to doing the standard name comparison.
166  */
167 static int msdos_cmp(const struct dentry *dentry,
168 		unsigned int len, const char *str, const struct qstr *name)
169 {
170 	struct fat_mount_options *options = &MSDOS_SB(dentry->d_sb)->options;
171 	unsigned char a_msdos_name[MSDOS_NAME], b_msdos_name[MSDOS_NAME];
172 	int error;
173 
174 	error = msdos_format_name(name->name, name->len, a_msdos_name, options);
175 	if (error)
176 		goto old_compare;
177 	error = msdos_format_name(str, len, b_msdos_name, options);
178 	if (error)
179 		goto old_compare;
180 	error = memcmp(a_msdos_name, b_msdos_name, MSDOS_NAME);
181 out:
182 	return error;
183 
184 old_compare:
185 	error = 1;
186 	if (name->len == len)
187 		error = memcmp(name->name, str, len);
188 	goto out;
189 }
190 
191 static const struct dentry_operations msdos_dentry_operations = {
192 	.d_hash		= msdos_hash,
193 	.d_compare	= msdos_cmp,
194 };
195 
196 /*
197  * AV. Wrappers for FAT sb operations. Is it wise?
198  */
199 
200 /***** Get inode using directory and name */
201 static struct dentry *msdos_lookup(struct inode *dir, struct dentry *dentry,
202 				   unsigned int flags)
203 {
204 	struct super_block *sb = dir->i_sb;
205 	struct fat_slot_info sinfo;
206 	struct inode *inode;
207 	int err;
208 
209 	mutex_lock(&MSDOS_SB(sb)->s_lock);
210 	err = msdos_find(dir, dentry->d_name.name, dentry->d_name.len, &sinfo);
211 	switch (err) {
212 	case -ENOENT:
213 		inode = NULL;
214 		break;
215 	case 0:
216 		inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos);
217 		brelse(sinfo.bh);
218 		break;
219 	default:
220 		inode = ERR_PTR(err);
221 	}
222 	mutex_unlock(&MSDOS_SB(sb)->s_lock);
223 	return d_splice_alias(inode, dentry);
224 }
225 
226 /***** Creates a directory entry (name is already formatted). */
227 static int msdos_add_entry(struct inode *dir, const unsigned char *name,
228 			   int is_dir, int is_hid, int cluster,
229 			   struct timespec64 *ts, struct fat_slot_info *sinfo)
230 {
231 	struct msdos_sb_info *sbi = MSDOS_SB(dir->i_sb);
232 	struct msdos_dir_entry de;
233 	__le16 time, date;
234 	int err;
235 
236 	memcpy(de.name, name, MSDOS_NAME);
237 	de.attr = is_dir ? ATTR_DIR : ATTR_ARCH;
238 	if (is_hid)
239 		de.attr |= ATTR_HIDDEN;
240 	de.lcase = 0;
241 	fat_time_unix2fat(sbi, ts, &time, &date, NULL);
242 	de.cdate = de.adate = 0;
243 	de.ctime = 0;
244 	de.ctime_cs = 0;
245 	de.time = time;
246 	de.date = date;
247 	fat_set_start(&de, cluster);
248 	de.size = 0;
249 
250 	err = fat_add_entries(dir, &de, 1, sinfo);
251 	if (err)
252 		return err;
253 
254 	fat_truncate_time(dir, ts, FAT_UPDATE_CMTIME);
255 	if (IS_DIRSYNC(dir))
256 		(void)fat_sync_inode(dir);
257 	else
258 		mark_inode_dirty(dir);
259 
260 	return 0;
261 }
262 
263 /***** Create a file */
264 static int msdos_create(struct mnt_idmap *idmap, struct inode *dir,
265 			struct dentry *dentry, umode_t mode, bool excl)
266 {
267 	struct super_block *sb = dir->i_sb;
268 	struct inode *inode = NULL;
269 	struct fat_slot_info sinfo;
270 	struct timespec64 ts;
271 	unsigned char msdos_name[MSDOS_NAME];
272 	int err, is_hid;
273 
274 	mutex_lock(&MSDOS_SB(sb)->s_lock);
275 
276 	err = msdos_format_name(dentry->d_name.name, dentry->d_name.len,
277 				msdos_name, &MSDOS_SB(sb)->options);
278 	if (err)
279 		goto out;
280 	is_hid = (dentry->d_name.name[0] == '.') && (msdos_name[0] != '.');
281 	/* Have to do it due to foo vs. .foo conflicts */
282 	if (!fat_scan(dir, msdos_name, &sinfo)) {
283 		brelse(sinfo.bh);
284 		err = -EINVAL;
285 		goto out;
286 	}
287 
288 	ts = current_time(dir);
289 	err = msdos_add_entry(dir, msdos_name, 0, is_hid, 0, &ts, &sinfo);
290 	if (err)
291 		goto out;
292 	inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos);
293 	brelse(sinfo.bh);
294 	if (IS_ERR(inode)) {
295 		err = PTR_ERR(inode);
296 		goto out;
297 	}
298 	fat_truncate_time(inode, &ts, FAT_UPDATE_ATIME | FAT_UPDATE_CMTIME);
299 	/* timestamp is already written, so mark_inode_dirty() is unneeded. */
300 
301 	d_instantiate(dentry, inode);
302 out:
303 	mutex_unlock(&MSDOS_SB(sb)->s_lock);
304 	if (!err)
305 		err = fat_flush_inodes(sb, dir, inode);
306 	return err;
307 }
308 
309 /***** Remove a directory */
310 static int msdos_rmdir(struct inode *dir, struct dentry *dentry)
311 {
312 	struct super_block *sb = dir->i_sb;
313 	struct inode *inode = d_inode(dentry);
314 	struct fat_slot_info sinfo;
315 	int err;
316 
317 	mutex_lock(&MSDOS_SB(sb)->s_lock);
318 	err = fat_dir_empty(inode);
319 	if (err)
320 		goto out;
321 	err = msdos_find(dir, dentry->d_name.name, dentry->d_name.len, &sinfo);
322 	if (err)
323 		goto out;
324 
325 	err = fat_remove_entries(dir, &sinfo);	/* and releases bh */
326 	if (err)
327 		goto out;
328 	drop_nlink(dir);
329 
330 	clear_nlink(inode);
331 	fat_detach(inode);
332 out:
333 	mutex_unlock(&MSDOS_SB(sb)->s_lock);
334 	if (!err)
335 		err = fat_flush_inodes(sb, dir, inode);
336 
337 	return err;
338 }
339 
340 /***** Make a directory */
341 static struct dentry *msdos_mkdir(struct mnt_idmap *idmap, struct inode *dir,
342 				  struct dentry *dentry, umode_t mode)
343 {
344 	struct super_block *sb = dir->i_sb;
345 	struct fat_slot_info sinfo;
346 	struct inode *inode;
347 	unsigned char msdos_name[MSDOS_NAME];
348 	struct timespec64 ts;
349 	int err, is_hid, cluster;
350 
351 	mutex_lock(&MSDOS_SB(sb)->s_lock);
352 
353 	err = msdos_format_name(dentry->d_name.name, dentry->d_name.len,
354 				msdos_name, &MSDOS_SB(sb)->options);
355 	if (err)
356 		goto out;
357 	is_hid = (dentry->d_name.name[0] == '.') && (msdos_name[0] != '.');
358 	/* foo vs .foo situation */
359 	if (!fat_scan(dir, msdos_name, &sinfo)) {
360 		brelse(sinfo.bh);
361 		err = -EINVAL;
362 		goto out;
363 	}
364 
365 	ts = current_time(dir);
366 	cluster = fat_alloc_new_dir(dir, &ts);
367 	if (cluster < 0) {
368 		err = cluster;
369 		goto out;
370 	}
371 	err = msdos_add_entry(dir, msdos_name, 1, is_hid, cluster, &ts, &sinfo);
372 	if (err)
373 		goto out_free;
374 	inc_nlink(dir);
375 
376 	inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos);
377 	brelse(sinfo.bh);
378 	if (IS_ERR(inode)) {
379 		err = PTR_ERR(inode);
380 		/* the directory was completed, just return a error */
381 		goto out;
382 	}
383 	set_nlink(inode, 2);
384 	fat_truncate_time(inode, &ts, FAT_UPDATE_ATIME | FAT_UPDATE_CMTIME);
385 	/* timestamp is already written, so mark_inode_dirty() is unneeded. */
386 
387 	d_instantiate(dentry, inode);
388 
389 	mutex_unlock(&MSDOS_SB(sb)->s_lock);
390 	fat_flush_inodes(sb, dir, inode);
391 	return NULL;
392 
393 out_free:
394 	fat_free_clusters(dir, cluster);
395 out:
396 	mutex_unlock(&MSDOS_SB(sb)->s_lock);
397 	return ERR_PTR(err);
398 }
399 
400 /***** Unlink a file */
401 static int msdos_unlink(struct inode *dir, struct dentry *dentry)
402 {
403 	struct inode *inode = d_inode(dentry);
404 	struct super_block *sb = inode->i_sb;
405 	struct fat_slot_info sinfo;
406 	int err;
407 
408 	mutex_lock(&MSDOS_SB(sb)->s_lock);
409 	err = msdos_find(dir, dentry->d_name.name, dentry->d_name.len, &sinfo);
410 	if (err)
411 		goto out;
412 
413 	err = fat_remove_entries(dir, &sinfo);	/* and releases bh */
414 	if (err)
415 		goto out;
416 	clear_nlink(inode);
417 	fat_detach(inode);
418 out:
419 	mutex_unlock(&MSDOS_SB(sb)->s_lock);
420 	if (!err)
421 		err = fat_flush_inodes(sb, dir, inode);
422 
423 	return err;
424 }
425 
426 static int do_msdos_rename(struct inode *old_dir, unsigned char *old_name,
427 			   struct dentry *old_dentry,
428 			   struct inode *new_dir, unsigned char *new_name,
429 			   struct dentry *new_dentry, int is_hid)
430 {
431 	struct buffer_head *dotdot_bh;
432 	struct msdos_dir_entry *dotdot_de;
433 	struct inode *old_inode, *new_inode;
434 	struct fat_slot_info old_sinfo, sinfo;
435 	struct timespec64 ts;
436 	loff_t new_i_pos;
437 	int err, old_attrs, is_dir, update_dotdot, corrupt = 0;
438 
439 	old_sinfo.bh = sinfo.bh = dotdot_bh = NULL;
440 	old_inode = d_inode(old_dentry);
441 	new_inode = d_inode(new_dentry);
442 
443 	err = fat_scan(old_dir, old_name, &old_sinfo);
444 	if (err) {
445 		err = -EIO;
446 		goto out;
447 	}
448 
449 	is_dir = S_ISDIR(old_inode->i_mode);
450 	update_dotdot = (is_dir && old_dir != new_dir);
451 	if (update_dotdot) {
452 		if (fat_get_dotdot_entry(old_inode, &dotdot_bh, &dotdot_de)) {
453 			err = -EIO;
454 			goto out;
455 		}
456 	}
457 
458 	old_attrs = MSDOS_I(old_inode)->i_attrs;
459 	err = fat_scan(new_dir, new_name, &sinfo);
460 	if (!err) {
461 		if (!new_inode) {
462 			/* "foo" -> ".foo" case. just change the ATTR_HIDDEN */
463 			if (sinfo.de != old_sinfo.de) {
464 				err = -EINVAL;
465 				goto out;
466 			}
467 			if (is_hid)
468 				MSDOS_I(old_inode)->i_attrs |= ATTR_HIDDEN;
469 			else
470 				MSDOS_I(old_inode)->i_attrs &= ~ATTR_HIDDEN;
471 			if (IS_DIRSYNC(old_dir)) {
472 				err = fat_sync_inode(old_inode);
473 				if (err) {
474 					MSDOS_I(old_inode)->i_attrs = old_attrs;
475 					goto out;
476 				}
477 			} else
478 				mark_inode_dirty(old_inode);
479 
480 			inode_inc_iversion(old_dir);
481 			fat_truncate_time(old_dir, NULL, FAT_UPDATE_CMTIME);
482 			if (IS_DIRSYNC(old_dir))
483 				(void)fat_sync_inode(old_dir);
484 			else
485 				mark_inode_dirty(old_dir);
486 			goto out;
487 		}
488 	}
489 
490 	ts = current_time(old_inode);
491 	if (new_inode) {
492 		if (err)
493 			goto out;
494 		if (is_dir) {
495 			err = fat_dir_empty(new_inode);
496 			if (err)
497 				goto out;
498 		}
499 		new_i_pos = MSDOS_I(new_inode)->i_pos;
500 		fat_detach(new_inode);
501 	} else {
502 		err = msdos_add_entry(new_dir, new_name, is_dir, is_hid, 0,
503 				      &ts, &sinfo);
504 		if (err)
505 			goto out;
506 		new_i_pos = sinfo.i_pos;
507 	}
508 	inode_inc_iversion(new_dir);
509 
510 	fat_detach(old_inode);
511 	fat_attach(old_inode, new_i_pos);
512 	if (is_hid)
513 		MSDOS_I(old_inode)->i_attrs |= ATTR_HIDDEN;
514 	else
515 		MSDOS_I(old_inode)->i_attrs &= ~ATTR_HIDDEN;
516 	if (IS_DIRSYNC(new_dir)) {
517 		err = fat_sync_inode(old_inode);
518 		if (err)
519 			goto error_inode;
520 	} else
521 		mark_inode_dirty(old_inode);
522 
523 	if (update_dotdot) {
524 		fat_set_start(dotdot_de, MSDOS_I(new_dir)->i_logstart);
525 		mark_buffer_dirty_inode(dotdot_bh, old_inode);
526 		if (IS_DIRSYNC(new_dir)) {
527 			err = sync_dirty_buffer(dotdot_bh);
528 			if (err)
529 				goto error_dotdot;
530 		}
531 		drop_nlink(old_dir);
532 		if (!new_inode)
533 			inc_nlink(new_dir);
534 	}
535 
536 	err = fat_remove_entries(old_dir, &old_sinfo);	/* and releases bh */
537 	old_sinfo.bh = NULL;
538 	if (err)
539 		goto error_dotdot;
540 	inode_inc_iversion(old_dir);
541 	fat_truncate_time(old_dir, &ts, FAT_UPDATE_CMTIME);
542 	if (IS_DIRSYNC(old_dir))
543 		(void)fat_sync_inode(old_dir);
544 	else
545 		mark_inode_dirty(old_dir);
546 
547 	if (new_inode) {
548 		drop_nlink(new_inode);
549 		if (is_dir)
550 			drop_nlink(new_inode);
551 	}
552 out:
553 	brelse(sinfo.bh);
554 	brelse(dotdot_bh);
555 	brelse(old_sinfo.bh);
556 	return err;
557 
558 error_dotdot:
559 	/* data cluster is shared, serious corruption */
560 	corrupt = 1;
561 
562 	if (update_dotdot) {
563 		fat_set_start(dotdot_de, MSDOS_I(old_dir)->i_logstart);
564 		mark_buffer_dirty_inode(dotdot_bh, old_inode);
565 		corrupt |= sync_dirty_buffer(dotdot_bh);
566 	}
567 error_inode:
568 	fat_detach(old_inode);
569 	fat_attach(old_inode, old_sinfo.i_pos);
570 	MSDOS_I(old_inode)->i_attrs = old_attrs;
571 	if (new_inode) {
572 		fat_attach(new_inode, new_i_pos);
573 		if (corrupt)
574 			corrupt |= fat_sync_inode(new_inode);
575 	} else {
576 		/*
577 		 * If new entry was not sharing the data cluster, it
578 		 * shouldn't be serious corruption.
579 		 */
580 		int err2 = fat_remove_entries(new_dir, &sinfo);
581 		if (corrupt)
582 			corrupt |= err2;
583 		sinfo.bh = NULL;
584 	}
585 	if (corrupt < 0) {
586 		fat_fs_error(new_dir->i_sb,
587 			     "%s: Filesystem corrupted (i_pos %lld)",
588 			     __func__, sinfo.i_pos);
589 	}
590 	goto out;
591 }
592 
593 /***** Rename, a wrapper for rename_same_dir & rename_diff_dir */
594 static int msdos_rename(struct mnt_idmap *idmap,
595 			struct inode *old_dir, struct dentry *old_dentry,
596 			struct inode *new_dir, struct dentry *new_dentry,
597 			unsigned int flags)
598 {
599 	struct super_block *sb = old_dir->i_sb;
600 	unsigned char old_msdos_name[MSDOS_NAME], new_msdos_name[MSDOS_NAME];
601 	int err, is_hid;
602 
603 	if (flags & ~RENAME_NOREPLACE)
604 		return -EINVAL;
605 
606 	mutex_lock(&MSDOS_SB(sb)->s_lock);
607 
608 	err = msdos_format_name(old_dentry->d_name.name,
609 				old_dentry->d_name.len, old_msdos_name,
610 				&MSDOS_SB(old_dir->i_sb)->options);
611 	if (err)
612 		goto out;
613 	err = msdos_format_name(new_dentry->d_name.name,
614 				new_dentry->d_name.len, new_msdos_name,
615 				&MSDOS_SB(new_dir->i_sb)->options);
616 	if (err)
617 		goto out;
618 
619 	is_hid =
620 	     (new_dentry->d_name.name[0] == '.') && (new_msdos_name[0] != '.');
621 
622 	err = do_msdos_rename(old_dir, old_msdos_name, old_dentry,
623 			      new_dir, new_msdos_name, new_dentry, is_hid);
624 out:
625 	mutex_unlock(&MSDOS_SB(sb)->s_lock);
626 	if (!err)
627 		err = fat_flush_inodes(sb, old_dir, new_dir);
628 	return err;
629 }
630 
631 static const struct inode_operations msdos_dir_inode_operations = {
632 	.create		= msdos_create,
633 	.lookup		= msdos_lookup,
634 	.unlink		= msdos_unlink,
635 	.mkdir		= msdos_mkdir,
636 	.rmdir		= msdos_rmdir,
637 	.rename		= msdos_rename,
638 	.setattr	= fat_setattr,
639 	.getattr	= fat_getattr,
640 	.update_time	= fat_update_time,
641 };
642 
643 static void setup(struct super_block *sb)
644 {
645 	MSDOS_SB(sb)->dir_ops = &msdos_dir_inode_operations;
646 	set_default_d_op(sb, &msdos_dentry_operations);
647 	sb->s_flags |= SB_NOATIME;
648 }
649 
650 static int msdos_fill_super(struct super_block *sb, struct fs_context *fc)
651 {
652 	return fat_fill_super(sb, fc, setup);
653 }
654 
655 static int msdos_get_tree(struct fs_context *fc)
656 {
657 	return get_tree_bdev(fc, msdos_fill_super);
658 }
659 
660 static int msdos_parse_param(struct fs_context *fc, struct fs_parameter *param)
661 {
662 	return fat_parse_param(fc, param, false);
663 }
664 
665 static const struct fs_context_operations msdos_context_ops = {
666 	.parse_param	= msdos_parse_param,
667 	.get_tree	= msdos_get_tree,
668 	.reconfigure	= fat_reconfigure,
669 	.free		= fat_free_fc,
670 };
671 
672 static int msdos_init_fs_context(struct fs_context *fc)
673 {
674 	int err;
675 
676 	/* Initialize with is_vfat == false */
677 	err = fat_init_fs_context(fc, false);
678 	if (err)
679 		return err;
680 
681 	fc->ops = &msdos_context_ops;
682 	return 0;
683 }
684 
685 static struct file_system_type msdos_fs_type = {
686 	.owner		= THIS_MODULE,
687 	.name		= "msdos",
688 	.kill_sb	= kill_block_super,
689 	.fs_flags	= FS_REQUIRES_DEV | FS_ALLOW_IDMAP,
690 	.init_fs_context = msdos_init_fs_context,
691 	.parameters	= fat_param_spec,
692 };
693 MODULE_ALIAS_FS("msdos");
694 
695 static int __init init_msdos_fs(void)
696 {
697 	return register_filesystem(&msdos_fs_type);
698 }
699 
700 static void __exit exit_msdos_fs(void)
701 {
702 	unregister_filesystem(&msdos_fs_type);
703 }
704 
705 MODULE_LICENSE("GPL");
706 MODULE_AUTHOR("Werner Almesberger");
707 MODULE_DESCRIPTION("MS-DOS filesystem support");
708 
709 module_init(init_msdos_fs)
710 module_exit(exit_msdos_fs)
711