xref: /openbmc/linux/fs/fat/inode.c (revision b60a5b8d)
1 /*
2  *  linux/fs/fat/inode.c
3  *
4  *  Written 1992,1993 by Werner Almesberger
5  *  VFAT extensions by Gordon Chaffee, merged with msdos fs by Henrik Storner
6  *  Rewritten for the constant inumbers support by Al Viro
7  *
8  *  Fixes:
9  *
10  *	Max Cohan: Fixed invalid FSINFO offset when info_sector is 0
11  */
12 
13 #include <linux/module.h>
14 #include <linux/pagemap.h>
15 #include <linux/mpage.h>
16 #include <linux/vfs.h>
17 #include <linux/seq_file.h>
18 #include <linux/parser.h>
19 #include <linux/uio.h>
20 #include <linux/blkdev.h>
21 #include <linux/backing-dev.h>
22 #include <asm/unaligned.h>
23 #include <linux/iversion.h>
24 #include "fat.h"
25 
26 #ifndef CONFIG_FAT_DEFAULT_IOCHARSET
27 /* if user don't select VFAT, this is undefined. */
28 #define CONFIG_FAT_DEFAULT_IOCHARSET	""
29 #endif
30 
31 #define KB_IN_SECTORS 2
32 
33 /*
34  * A deserialized copy of the on-disk structure laid out in struct
35  * fat_boot_sector.
36  */
37 struct fat_bios_param_block {
38 	u16	fat_sector_size;
39 	u8	fat_sec_per_clus;
40 	u16	fat_reserved;
41 	u8	fat_fats;
42 	u16	fat_dir_entries;
43 	u16	fat_sectors;
44 	u16	fat_fat_length;
45 	u32	fat_total_sect;
46 
47 	u8	fat16_state;
48 	u32	fat16_vol_id;
49 
50 	u32	fat32_length;
51 	u32	fat32_root_cluster;
52 	u16	fat32_info_sector;
53 	u8	fat32_state;
54 	u32	fat32_vol_id;
55 };
56 
57 static int fat_default_codepage = CONFIG_FAT_DEFAULT_CODEPAGE;
58 static char fat_default_iocharset[] = CONFIG_FAT_DEFAULT_IOCHARSET;
59 
60 static struct fat_floppy_defaults {
61 	unsigned nr_sectors;
62 	unsigned sec_per_clus;
63 	unsigned dir_entries;
64 	unsigned media;
65 	unsigned fat_length;
66 } floppy_defaults[] = {
67 {
68 	.nr_sectors = 160 * KB_IN_SECTORS,
69 	.sec_per_clus = 1,
70 	.dir_entries = 64,
71 	.media = 0xFE,
72 	.fat_length = 1,
73 },
74 {
75 	.nr_sectors = 180 * KB_IN_SECTORS,
76 	.sec_per_clus = 1,
77 	.dir_entries = 64,
78 	.media = 0xFC,
79 	.fat_length = 2,
80 },
81 {
82 	.nr_sectors = 320 * KB_IN_SECTORS,
83 	.sec_per_clus = 2,
84 	.dir_entries = 112,
85 	.media = 0xFF,
86 	.fat_length = 1,
87 },
88 {
89 	.nr_sectors = 360 * KB_IN_SECTORS,
90 	.sec_per_clus = 2,
91 	.dir_entries = 112,
92 	.media = 0xFD,
93 	.fat_length = 2,
94 },
95 };
96 
97 int fat_add_cluster(struct inode *inode)
98 {
99 	int err, cluster;
100 
101 	err = fat_alloc_clusters(inode, &cluster, 1);
102 	if (err)
103 		return err;
104 	/* FIXME: this cluster should be added after data of this
105 	 * cluster is writed */
106 	err = fat_chain_add(inode, cluster, 1);
107 	if (err)
108 		fat_free_clusters(inode, cluster);
109 	return err;
110 }
111 
112 static inline int __fat_get_block(struct inode *inode, sector_t iblock,
113 				  unsigned long *max_blocks,
114 				  struct buffer_head *bh_result, int create)
115 {
116 	struct super_block *sb = inode->i_sb;
117 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
118 	unsigned long mapped_blocks;
119 	sector_t phys, last_block;
120 	int err, offset;
121 
122 	err = fat_bmap(inode, iblock, &phys, &mapped_blocks, create, false);
123 	if (err)
124 		return err;
125 	if (phys) {
126 		map_bh(bh_result, sb, phys);
127 		*max_blocks = min(mapped_blocks, *max_blocks);
128 		return 0;
129 	}
130 	if (!create)
131 		return 0;
132 
133 	if (iblock != MSDOS_I(inode)->mmu_private >> sb->s_blocksize_bits) {
134 		fat_fs_error(sb, "corrupted file size (i_pos %lld, %lld)",
135 			MSDOS_I(inode)->i_pos, MSDOS_I(inode)->mmu_private);
136 		return -EIO;
137 	}
138 
139 	last_block = inode->i_blocks >> (sb->s_blocksize_bits - 9);
140 	offset = (unsigned long)iblock & (sbi->sec_per_clus - 1);
141 	/*
142 	 * allocate a cluster according to the following.
143 	 * 1) no more available blocks
144 	 * 2) not part of fallocate region
145 	 */
146 	if (!offset && !(iblock < last_block)) {
147 		/* TODO: multiple cluster allocation would be desirable. */
148 		err = fat_add_cluster(inode);
149 		if (err)
150 			return err;
151 	}
152 	/* available blocks on this cluster */
153 	mapped_blocks = sbi->sec_per_clus - offset;
154 
155 	*max_blocks = min(mapped_blocks, *max_blocks);
156 	MSDOS_I(inode)->mmu_private += *max_blocks << sb->s_blocksize_bits;
157 
158 	err = fat_bmap(inode, iblock, &phys, &mapped_blocks, create, false);
159 	if (err)
160 		return err;
161 	if (!phys) {
162 		fat_fs_error(sb,
163 			     "invalid FAT chain (i_pos %lld, last_block %llu)",
164 			     MSDOS_I(inode)->i_pos,
165 			     (unsigned long long)last_block);
166 		return -EIO;
167 	}
168 
169 	BUG_ON(*max_blocks != mapped_blocks);
170 	set_buffer_new(bh_result);
171 	map_bh(bh_result, sb, phys);
172 
173 	return 0;
174 }
175 
176 static int fat_get_block(struct inode *inode, sector_t iblock,
177 			 struct buffer_head *bh_result, int create)
178 {
179 	struct super_block *sb = inode->i_sb;
180 	unsigned long max_blocks = bh_result->b_size >> inode->i_blkbits;
181 	int err;
182 
183 	err = __fat_get_block(inode, iblock, &max_blocks, bh_result, create);
184 	if (err)
185 		return err;
186 	bh_result->b_size = max_blocks << sb->s_blocksize_bits;
187 	return 0;
188 }
189 
190 static int fat_writepage(struct page *page, struct writeback_control *wbc)
191 {
192 	return block_write_full_page(page, fat_get_block, wbc);
193 }
194 
195 static int fat_writepages(struct address_space *mapping,
196 			  struct writeback_control *wbc)
197 {
198 	return mpage_writepages(mapping, wbc, fat_get_block);
199 }
200 
201 static int fat_readpage(struct file *file, struct page *page)
202 {
203 	return mpage_readpage(page, fat_get_block);
204 }
205 
206 static int fat_readpages(struct file *file, struct address_space *mapping,
207 			 struct list_head *pages, unsigned nr_pages)
208 {
209 	return mpage_readpages(mapping, pages, nr_pages, fat_get_block);
210 }
211 
212 static void fat_write_failed(struct address_space *mapping, loff_t to)
213 {
214 	struct inode *inode = mapping->host;
215 
216 	if (to > inode->i_size) {
217 		truncate_pagecache(inode, inode->i_size);
218 		fat_truncate_blocks(inode, inode->i_size);
219 	}
220 }
221 
222 static int fat_write_begin(struct file *file, struct address_space *mapping,
223 			loff_t pos, unsigned len, unsigned flags,
224 			struct page **pagep, void **fsdata)
225 {
226 	int err;
227 
228 	*pagep = NULL;
229 	err = cont_write_begin(file, mapping, pos, len, flags,
230 				pagep, fsdata, fat_get_block,
231 				&MSDOS_I(mapping->host)->mmu_private);
232 	if (err < 0)
233 		fat_write_failed(mapping, pos + len);
234 	return err;
235 }
236 
237 static int fat_write_end(struct file *file, struct address_space *mapping,
238 			loff_t pos, unsigned len, unsigned copied,
239 			struct page *pagep, void *fsdata)
240 {
241 	struct inode *inode = mapping->host;
242 	int err;
243 	err = generic_write_end(file, mapping, pos, len, copied, pagep, fsdata);
244 	if (err < len)
245 		fat_write_failed(mapping, pos + len);
246 	if (!(err < 0) && !(MSDOS_I(inode)->i_attrs & ATTR_ARCH)) {
247 		fat_truncate_time(inode, NULL, S_CTIME|S_MTIME);
248 		MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
249 		mark_inode_dirty(inode);
250 	}
251 	return err;
252 }
253 
254 static ssize_t fat_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
255 {
256 	struct file *file = iocb->ki_filp;
257 	struct address_space *mapping = file->f_mapping;
258 	struct inode *inode = mapping->host;
259 	size_t count = iov_iter_count(iter);
260 	loff_t offset = iocb->ki_pos;
261 	ssize_t ret;
262 
263 	if (iov_iter_rw(iter) == WRITE) {
264 		/*
265 		 * FIXME: blockdev_direct_IO() doesn't use ->write_begin(),
266 		 * so we need to update the ->mmu_private to block boundary.
267 		 *
268 		 * But we must fill the remaining area or hole by nul for
269 		 * updating ->mmu_private.
270 		 *
271 		 * Return 0, and fallback to normal buffered write.
272 		 */
273 		loff_t size = offset + count;
274 		if (MSDOS_I(inode)->mmu_private < size)
275 			return 0;
276 	}
277 
278 	/*
279 	 * FAT need to use the DIO_LOCKING for avoiding the race
280 	 * condition of fat_get_block() and ->truncate().
281 	 */
282 	ret = blockdev_direct_IO(iocb, inode, iter, fat_get_block);
283 	if (ret < 0 && iov_iter_rw(iter) == WRITE)
284 		fat_write_failed(mapping, offset + count);
285 
286 	return ret;
287 }
288 
289 static int fat_get_block_bmap(struct inode *inode, sector_t iblock,
290 		struct buffer_head *bh_result, int create)
291 {
292 	struct super_block *sb = inode->i_sb;
293 	unsigned long max_blocks = bh_result->b_size >> inode->i_blkbits;
294 	int err;
295 	sector_t bmap;
296 	unsigned long mapped_blocks;
297 
298 	BUG_ON(create != 0);
299 
300 	err = fat_bmap(inode, iblock, &bmap, &mapped_blocks, create, true);
301 	if (err)
302 		return err;
303 
304 	if (bmap) {
305 		map_bh(bh_result, sb, bmap);
306 		max_blocks = min(mapped_blocks, max_blocks);
307 	}
308 
309 	bh_result->b_size = max_blocks << sb->s_blocksize_bits;
310 
311 	return 0;
312 }
313 
314 static sector_t _fat_bmap(struct address_space *mapping, sector_t block)
315 {
316 	sector_t blocknr;
317 
318 	/* fat_get_cluster() assumes the requested blocknr isn't truncated. */
319 	down_read(&MSDOS_I(mapping->host)->truncate_lock);
320 	blocknr = generic_block_bmap(mapping, block, fat_get_block_bmap);
321 	up_read(&MSDOS_I(mapping->host)->truncate_lock);
322 
323 	return blocknr;
324 }
325 
326 /*
327  * fat_block_truncate_page() zeroes out a mapping from file offset `from'
328  * up to the end of the block which corresponds to `from'.
329  * This is required during truncate to physically zeroout the tail end
330  * of that block so it doesn't yield old data if the file is later grown.
331  * Also, avoid causing failure from fsx for cases of "data past EOF"
332  */
333 int fat_block_truncate_page(struct inode *inode, loff_t from)
334 {
335 	return block_truncate_page(inode->i_mapping, from, fat_get_block);
336 }
337 
338 static const struct address_space_operations fat_aops = {
339 	.readpage	= fat_readpage,
340 	.readpages	= fat_readpages,
341 	.writepage	= fat_writepage,
342 	.writepages	= fat_writepages,
343 	.write_begin	= fat_write_begin,
344 	.write_end	= fat_write_end,
345 	.direct_IO	= fat_direct_IO,
346 	.bmap		= _fat_bmap
347 };
348 
349 /*
350  * New FAT inode stuff. We do the following:
351  *	a) i_ino is constant and has nothing with on-disk location.
352  *	b) FAT manages its own cache of directory entries.
353  *	c) *This* cache is indexed by on-disk location.
354  *	d) inode has an associated directory entry, all right, but
355  *		it may be unhashed.
356  *	e) currently entries are stored within struct inode. That should
357  *		change.
358  *	f) we deal with races in the following way:
359  *		1. readdir() and lookup() do FAT-dir-cache lookup.
360  *		2. rename() unhashes the F-d-c entry and rehashes it in
361  *			a new place.
362  *		3. unlink() and rmdir() unhash F-d-c entry.
363  *		4. fat_write_inode() checks whether the thing is unhashed.
364  *			If it is we silently return. If it isn't we do bread(),
365  *			check if the location is still valid and retry if it
366  *			isn't. Otherwise we do changes.
367  *		5. Spinlock is used to protect hash/unhash/location check/lookup
368  *		6. fat_evict_inode() unhashes the F-d-c entry.
369  *		7. lookup() and readdir() do igrab() if they find a F-d-c entry
370  *			and consider negative result as cache miss.
371  */
372 
373 static void fat_hash_init(struct super_block *sb)
374 {
375 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
376 	int i;
377 
378 	spin_lock_init(&sbi->inode_hash_lock);
379 	for (i = 0; i < FAT_HASH_SIZE; i++)
380 		INIT_HLIST_HEAD(&sbi->inode_hashtable[i]);
381 }
382 
383 static inline unsigned long fat_hash(loff_t i_pos)
384 {
385 	return hash_32(i_pos, FAT_HASH_BITS);
386 }
387 
388 static void dir_hash_init(struct super_block *sb)
389 {
390 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
391 	int i;
392 
393 	spin_lock_init(&sbi->dir_hash_lock);
394 	for (i = 0; i < FAT_HASH_SIZE; i++)
395 		INIT_HLIST_HEAD(&sbi->dir_hashtable[i]);
396 }
397 
398 void fat_attach(struct inode *inode, loff_t i_pos)
399 {
400 	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
401 
402 	if (inode->i_ino != MSDOS_ROOT_INO) {
403 		struct hlist_head *head =   sbi->inode_hashtable
404 					  + fat_hash(i_pos);
405 
406 		spin_lock(&sbi->inode_hash_lock);
407 		MSDOS_I(inode)->i_pos = i_pos;
408 		hlist_add_head(&MSDOS_I(inode)->i_fat_hash, head);
409 		spin_unlock(&sbi->inode_hash_lock);
410 	}
411 
412 	/* If NFS support is enabled, cache the mapping of start cluster
413 	 * to directory inode. This is used during reconnection of
414 	 * dentries to the filesystem root.
415 	 */
416 	if (S_ISDIR(inode->i_mode) && sbi->options.nfs) {
417 		struct hlist_head *d_head = sbi->dir_hashtable;
418 		d_head += fat_dir_hash(MSDOS_I(inode)->i_logstart);
419 
420 		spin_lock(&sbi->dir_hash_lock);
421 		hlist_add_head(&MSDOS_I(inode)->i_dir_hash, d_head);
422 		spin_unlock(&sbi->dir_hash_lock);
423 	}
424 }
425 EXPORT_SYMBOL_GPL(fat_attach);
426 
427 void fat_detach(struct inode *inode)
428 {
429 	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
430 	spin_lock(&sbi->inode_hash_lock);
431 	MSDOS_I(inode)->i_pos = 0;
432 	hlist_del_init(&MSDOS_I(inode)->i_fat_hash);
433 	spin_unlock(&sbi->inode_hash_lock);
434 
435 	if (S_ISDIR(inode->i_mode) && sbi->options.nfs) {
436 		spin_lock(&sbi->dir_hash_lock);
437 		hlist_del_init(&MSDOS_I(inode)->i_dir_hash);
438 		spin_unlock(&sbi->dir_hash_lock);
439 	}
440 }
441 EXPORT_SYMBOL_GPL(fat_detach);
442 
443 struct inode *fat_iget(struct super_block *sb, loff_t i_pos)
444 {
445 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
446 	struct hlist_head *head = sbi->inode_hashtable + fat_hash(i_pos);
447 	struct msdos_inode_info *i;
448 	struct inode *inode = NULL;
449 
450 	spin_lock(&sbi->inode_hash_lock);
451 	hlist_for_each_entry(i, head, i_fat_hash) {
452 		BUG_ON(i->vfs_inode.i_sb != sb);
453 		if (i->i_pos != i_pos)
454 			continue;
455 		inode = igrab(&i->vfs_inode);
456 		if (inode)
457 			break;
458 	}
459 	spin_unlock(&sbi->inode_hash_lock);
460 	return inode;
461 }
462 
463 static int is_exec(unsigned char *extension)
464 {
465 	unsigned char exe_extensions[] = "EXECOMBAT", *walk;
466 
467 	for (walk = exe_extensions; *walk; walk += 3)
468 		if (!strncmp(extension, walk, 3))
469 			return 1;
470 	return 0;
471 }
472 
473 static int fat_calc_dir_size(struct inode *inode)
474 {
475 	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
476 	int ret, fclus, dclus;
477 
478 	inode->i_size = 0;
479 	if (MSDOS_I(inode)->i_start == 0)
480 		return 0;
481 
482 	ret = fat_get_cluster(inode, FAT_ENT_EOF, &fclus, &dclus);
483 	if (ret < 0)
484 		return ret;
485 	inode->i_size = (fclus + 1) << sbi->cluster_bits;
486 
487 	return 0;
488 }
489 
490 static int fat_validate_dir(struct inode *dir)
491 {
492 	struct super_block *sb = dir->i_sb;
493 
494 	if (dir->i_nlink < 2) {
495 		/* Directory should have "."/".." entries at least. */
496 		fat_fs_error(sb, "corrupted directory (invalid entries)");
497 		return -EIO;
498 	}
499 	if (MSDOS_I(dir)->i_start == 0 ||
500 	    MSDOS_I(dir)->i_start == MSDOS_SB(sb)->root_cluster) {
501 		/* Directory should point valid cluster. */
502 		fat_fs_error(sb, "corrupted directory (invalid i_start)");
503 		return -EIO;
504 	}
505 	return 0;
506 }
507 
508 /* doesn't deal with root inode */
509 int fat_fill_inode(struct inode *inode, struct msdos_dir_entry *de)
510 {
511 	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
512 	int error;
513 
514 	MSDOS_I(inode)->i_pos = 0;
515 	inode->i_uid = sbi->options.fs_uid;
516 	inode->i_gid = sbi->options.fs_gid;
517 	inode_inc_iversion(inode);
518 	inode->i_generation = get_seconds();
519 
520 	if ((de->attr & ATTR_DIR) && !IS_FREE(de->name)) {
521 		inode->i_generation &= ~1;
522 		inode->i_mode = fat_make_mode(sbi, de->attr, S_IRWXUGO);
523 		inode->i_op = sbi->dir_ops;
524 		inode->i_fop = &fat_dir_operations;
525 
526 		MSDOS_I(inode)->i_start = fat_get_start(sbi, de);
527 		MSDOS_I(inode)->i_logstart = MSDOS_I(inode)->i_start;
528 		error = fat_calc_dir_size(inode);
529 		if (error < 0)
530 			return error;
531 		MSDOS_I(inode)->mmu_private = inode->i_size;
532 
533 		set_nlink(inode, fat_subdirs(inode));
534 
535 		error = fat_validate_dir(inode);
536 		if (error < 0)
537 			return error;
538 	} else { /* not a directory */
539 		inode->i_generation |= 1;
540 		inode->i_mode = fat_make_mode(sbi, de->attr,
541 			((sbi->options.showexec && !is_exec(de->name + 8))
542 			 ? S_IRUGO|S_IWUGO : S_IRWXUGO));
543 		MSDOS_I(inode)->i_start = fat_get_start(sbi, de);
544 
545 		MSDOS_I(inode)->i_logstart = MSDOS_I(inode)->i_start;
546 		inode->i_size = le32_to_cpu(de->size);
547 		inode->i_op = &fat_file_inode_operations;
548 		inode->i_fop = &fat_file_operations;
549 		inode->i_mapping->a_ops = &fat_aops;
550 		MSDOS_I(inode)->mmu_private = inode->i_size;
551 	}
552 	if (de->attr & ATTR_SYS) {
553 		if (sbi->options.sys_immutable)
554 			inode->i_flags |= S_IMMUTABLE;
555 	}
556 	fat_save_attrs(inode, de->attr);
557 
558 	inode->i_blocks = ((inode->i_size + (sbi->cluster_size - 1))
559 			   & ~((loff_t)sbi->cluster_size - 1)) >> 9;
560 
561 	fat_time_fat2unix(sbi, &inode->i_mtime, de->time, de->date, 0);
562 	if (sbi->options.isvfat) {
563 		fat_time_fat2unix(sbi, &inode->i_ctime, de->ctime,
564 				  de->cdate, de->ctime_cs);
565 		fat_time_fat2unix(sbi, &inode->i_atime, 0, de->adate, 0);
566 	} else
567 		fat_truncate_time(inode, &inode->i_mtime, S_ATIME|S_CTIME);
568 
569 	return 0;
570 }
571 
572 static inline void fat_lock_build_inode(struct msdos_sb_info *sbi)
573 {
574 	if (sbi->options.nfs == FAT_NFS_NOSTALE_RO)
575 		mutex_lock(&sbi->nfs_build_inode_lock);
576 }
577 
578 static inline void fat_unlock_build_inode(struct msdos_sb_info *sbi)
579 {
580 	if (sbi->options.nfs == FAT_NFS_NOSTALE_RO)
581 		mutex_unlock(&sbi->nfs_build_inode_lock);
582 }
583 
584 struct inode *fat_build_inode(struct super_block *sb,
585 			struct msdos_dir_entry *de, loff_t i_pos)
586 {
587 	struct inode *inode;
588 	int err;
589 
590 	fat_lock_build_inode(MSDOS_SB(sb));
591 	inode = fat_iget(sb, i_pos);
592 	if (inode)
593 		goto out;
594 	inode = new_inode(sb);
595 	if (!inode) {
596 		inode = ERR_PTR(-ENOMEM);
597 		goto out;
598 	}
599 	inode->i_ino = iunique(sb, MSDOS_ROOT_INO);
600 	inode_set_iversion(inode, 1);
601 	err = fat_fill_inode(inode, de);
602 	if (err) {
603 		iput(inode);
604 		inode = ERR_PTR(err);
605 		goto out;
606 	}
607 	fat_attach(inode, i_pos);
608 	insert_inode_hash(inode);
609 out:
610 	fat_unlock_build_inode(MSDOS_SB(sb));
611 	return inode;
612 }
613 
614 EXPORT_SYMBOL_GPL(fat_build_inode);
615 
616 static int __fat_write_inode(struct inode *inode, int wait);
617 
618 static void fat_free_eofblocks(struct inode *inode)
619 {
620 	/* Release unwritten fallocated blocks on inode eviction. */
621 	if ((inode->i_blocks << 9) >
622 			round_up(MSDOS_I(inode)->mmu_private,
623 				MSDOS_SB(inode->i_sb)->cluster_size)) {
624 		int err;
625 
626 		fat_truncate_blocks(inode, MSDOS_I(inode)->mmu_private);
627 		/* Fallocate results in updating the i_start/iogstart
628 		 * for the zero byte file. So, make it return to
629 		 * original state during evict and commit it to avoid
630 		 * any corruption on the next access to the cluster
631 		 * chain for the file.
632 		 */
633 		err = __fat_write_inode(inode, inode_needs_sync(inode));
634 		if (err) {
635 			fat_msg(inode->i_sb, KERN_WARNING, "Failed to "
636 					"update on disk inode for unused "
637 					"fallocated blocks, inode could be "
638 					"corrupted. Please run fsck");
639 		}
640 
641 	}
642 }
643 
644 static void fat_evict_inode(struct inode *inode)
645 {
646 	truncate_inode_pages_final(&inode->i_data);
647 	if (!inode->i_nlink) {
648 		inode->i_size = 0;
649 		fat_truncate_blocks(inode, 0);
650 	} else
651 		fat_free_eofblocks(inode);
652 
653 	invalidate_inode_buffers(inode);
654 	clear_inode(inode);
655 	fat_cache_inval_inode(inode);
656 	fat_detach(inode);
657 }
658 
659 static void fat_set_state(struct super_block *sb,
660 			unsigned int set, unsigned int force)
661 {
662 	struct buffer_head *bh;
663 	struct fat_boot_sector *b;
664 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
665 
666 	/* do not change any thing if mounted read only */
667 	if (sb_rdonly(sb) && !force)
668 		return;
669 
670 	/* do not change state if fs was dirty */
671 	if (sbi->dirty) {
672 		/* warn only on set (mount). */
673 		if (set)
674 			fat_msg(sb, KERN_WARNING, "Volume was not properly "
675 				"unmounted. Some data may be corrupt. "
676 				"Please run fsck.");
677 		return;
678 	}
679 
680 	bh = sb_bread(sb, 0);
681 	if (bh == NULL) {
682 		fat_msg(sb, KERN_ERR, "unable to read boot sector "
683 			"to mark fs as dirty");
684 		return;
685 	}
686 
687 	b = (struct fat_boot_sector *) bh->b_data;
688 
689 	if (is_fat32(sbi)) {
690 		if (set)
691 			b->fat32.state |= FAT_STATE_DIRTY;
692 		else
693 			b->fat32.state &= ~FAT_STATE_DIRTY;
694 	} else /* fat 16 and 12 */ {
695 		if (set)
696 			b->fat16.state |= FAT_STATE_DIRTY;
697 		else
698 			b->fat16.state &= ~FAT_STATE_DIRTY;
699 	}
700 
701 	mark_buffer_dirty(bh);
702 	sync_dirty_buffer(bh);
703 	brelse(bh);
704 }
705 
706 static void fat_reset_iocharset(struct fat_mount_options *opts)
707 {
708 	if (opts->iocharset != fat_default_iocharset) {
709 		/* Note: opts->iocharset can be NULL here */
710 		kfree(opts->iocharset);
711 		opts->iocharset = fat_default_iocharset;
712 	}
713 }
714 
715 static void delayed_free(struct rcu_head *p)
716 {
717 	struct msdos_sb_info *sbi = container_of(p, struct msdos_sb_info, rcu);
718 	unload_nls(sbi->nls_disk);
719 	unload_nls(sbi->nls_io);
720 	fat_reset_iocharset(&sbi->options);
721 	kfree(sbi);
722 }
723 
724 static void fat_put_super(struct super_block *sb)
725 {
726 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
727 
728 	fat_set_state(sb, 0, 0);
729 
730 	iput(sbi->fsinfo_inode);
731 	iput(sbi->fat_inode);
732 
733 	call_rcu(&sbi->rcu, delayed_free);
734 }
735 
736 static struct kmem_cache *fat_inode_cachep;
737 
738 static struct inode *fat_alloc_inode(struct super_block *sb)
739 {
740 	struct msdos_inode_info *ei;
741 	ei = kmem_cache_alloc(fat_inode_cachep, GFP_NOFS);
742 	if (!ei)
743 		return NULL;
744 
745 	init_rwsem(&ei->truncate_lock);
746 	return &ei->vfs_inode;
747 }
748 
749 static void fat_i_callback(struct rcu_head *head)
750 {
751 	struct inode *inode = container_of(head, struct inode, i_rcu);
752 	kmem_cache_free(fat_inode_cachep, MSDOS_I(inode));
753 }
754 
755 static void fat_destroy_inode(struct inode *inode)
756 {
757 	call_rcu(&inode->i_rcu, fat_i_callback);
758 }
759 
760 static void init_once(void *foo)
761 {
762 	struct msdos_inode_info *ei = (struct msdos_inode_info *)foo;
763 
764 	spin_lock_init(&ei->cache_lru_lock);
765 	ei->nr_caches = 0;
766 	ei->cache_valid_id = FAT_CACHE_VALID + 1;
767 	INIT_LIST_HEAD(&ei->cache_lru);
768 	INIT_HLIST_NODE(&ei->i_fat_hash);
769 	INIT_HLIST_NODE(&ei->i_dir_hash);
770 	inode_init_once(&ei->vfs_inode);
771 }
772 
773 static int __init fat_init_inodecache(void)
774 {
775 	fat_inode_cachep = kmem_cache_create("fat_inode_cache",
776 					     sizeof(struct msdos_inode_info),
777 					     0, (SLAB_RECLAIM_ACCOUNT|
778 						SLAB_MEM_SPREAD|SLAB_ACCOUNT),
779 					     init_once);
780 	if (fat_inode_cachep == NULL)
781 		return -ENOMEM;
782 	return 0;
783 }
784 
785 static void __exit fat_destroy_inodecache(void)
786 {
787 	/*
788 	 * Make sure all delayed rcu free inodes are flushed before we
789 	 * destroy cache.
790 	 */
791 	rcu_barrier();
792 	kmem_cache_destroy(fat_inode_cachep);
793 }
794 
795 static int fat_remount(struct super_block *sb, int *flags, char *data)
796 {
797 	bool new_rdonly;
798 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
799 	*flags |= SB_NODIRATIME | (sbi->options.isvfat ? 0 : SB_NOATIME);
800 
801 	sync_filesystem(sb);
802 
803 	/* make sure we update state on remount. */
804 	new_rdonly = *flags & SB_RDONLY;
805 	if (new_rdonly != sb_rdonly(sb)) {
806 		if (new_rdonly)
807 			fat_set_state(sb, 0, 0);
808 		else
809 			fat_set_state(sb, 1, 1);
810 	}
811 	return 0;
812 }
813 
814 static int fat_statfs(struct dentry *dentry, struct kstatfs *buf)
815 {
816 	struct super_block *sb = dentry->d_sb;
817 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
818 	u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
819 
820 	/* If the count of free cluster is still unknown, counts it here. */
821 	if (sbi->free_clusters == -1 || !sbi->free_clus_valid) {
822 		int err = fat_count_free_clusters(dentry->d_sb);
823 		if (err)
824 			return err;
825 	}
826 
827 	buf->f_type = dentry->d_sb->s_magic;
828 	buf->f_bsize = sbi->cluster_size;
829 	buf->f_blocks = sbi->max_cluster - FAT_START_ENT;
830 	buf->f_bfree = sbi->free_clusters;
831 	buf->f_bavail = sbi->free_clusters;
832 	buf->f_fsid.val[0] = (u32)id;
833 	buf->f_fsid.val[1] = (u32)(id >> 32);
834 	buf->f_namelen =
835 		(sbi->options.isvfat ? FAT_LFN_LEN : 12) * NLS_MAX_CHARSET_SIZE;
836 
837 	return 0;
838 }
839 
840 static int __fat_write_inode(struct inode *inode, int wait)
841 {
842 	struct super_block *sb = inode->i_sb;
843 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
844 	struct buffer_head *bh;
845 	struct msdos_dir_entry *raw_entry;
846 	loff_t i_pos;
847 	sector_t blocknr;
848 	int err, offset;
849 
850 	if (inode->i_ino == MSDOS_ROOT_INO)
851 		return 0;
852 
853 retry:
854 	i_pos = fat_i_pos_read(sbi, inode);
855 	if (!i_pos)
856 		return 0;
857 
858 	fat_get_blknr_offset(sbi, i_pos, &blocknr, &offset);
859 	bh = sb_bread(sb, blocknr);
860 	if (!bh) {
861 		fat_msg(sb, KERN_ERR, "unable to read inode block "
862 		       "for updating (i_pos %lld)", i_pos);
863 		return -EIO;
864 	}
865 	spin_lock(&sbi->inode_hash_lock);
866 	if (i_pos != MSDOS_I(inode)->i_pos) {
867 		spin_unlock(&sbi->inode_hash_lock);
868 		brelse(bh);
869 		goto retry;
870 	}
871 
872 	raw_entry = &((struct msdos_dir_entry *) (bh->b_data))[offset];
873 	if (S_ISDIR(inode->i_mode))
874 		raw_entry->size = 0;
875 	else
876 		raw_entry->size = cpu_to_le32(inode->i_size);
877 	raw_entry->attr = fat_make_attrs(inode);
878 	fat_set_start(raw_entry, MSDOS_I(inode)->i_logstart);
879 	fat_time_unix2fat(sbi, &inode->i_mtime, &raw_entry->time,
880 			  &raw_entry->date, NULL);
881 	if (sbi->options.isvfat) {
882 		__le16 atime;
883 		fat_time_unix2fat(sbi, &inode->i_ctime, &raw_entry->ctime,
884 				  &raw_entry->cdate, &raw_entry->ctime_cs);
885 		fat_time_unix2fat(sbi, &inode->i_atime, &atime,
886 				  &raw_entry->adate, NULL);
887 	}
888 	spin_unlock(&sbi->inode_hash_lock);
889 	mark_buffer_dirty(bh);
890 	err = 0;
891 	if (wait)
892 		err = sync_dirty_buffer(bh);
893 	brelse(bh);
894 	return err;
895 }
896 
897 static int fat_write_inode(struct inode *inode, struct writeback_control *wbc)
898 {
899 	int err;
900 
901 	if (inode->i_ino == MSDOS_FSINFO_INO) {
902 		struct super_block *sb = inode->i_sb;
903 
904 		mutex_lock(&MSDOS_SB(sb)->s_lock);
905 		err = fat_clusters_flush(sb);
906 		mutex_unlock(&MSDOS_SB(sb)->s_lock);
907 	} else
908 		err = __fat_write_inode(inode, wbc->sync_mode == WB_SYNC_ALL);
909 
910 	return err;
911 }
912 
913 int fat_sync_inode(struct inode *inode)
914 {
915 	return __fat_write_inode(inode, 1);
916 }
917 
918 EXPORT_SYMBOL_GPL(fat_sync_inode);
919 
920 static int fat_show_options(struct seq_file *m, struct dentry *root);
921 static const struct super_operations fat_sops = {
922 	.alloc_inode	= fat_alloc_inode,
923 	.destroy_inode	= fat_destroy_inode,
924 	.write_inode	= fat_write_inode,
925 	.evict_inode	= fat_evict_inode,
926 	.put_super	= fat_put_super,
927 	.statfs		= fat_statfs,
928 	.remount_fs	= fat_remount,
929 
930 	.show_options	= fat_show_options,
931 };
932 
933 static int fat_show_options(struct seq_file *m, struct dentry *root)
934 {
935 	struct msdos_sb_info *sbi = MSDOS_SB(root->d_sb);
936 	struct fat_mount_options *opts = &sbi->options;
937 	int isvfat = opts->isvfat;
938 
939 	if (!uid_eq(opts->fs_uid, GLOBAL_ROOT_UID))
940 		seq_printf(m, ",uid=%u",
941 				from_kuid_munged(&init_user_ns, opts->fs_uid));
942 	if (!gid_eq(opts->fs_gid, GLOBAL_ROOT_GID))
943 		seq_printf(m, ",gid=%u",
944 				from_kgid_munged(&init_user_ns, opts->fs_gid));
945 	seq_printf(m, ",fmask=%04o", opts->fs_fmask);
946 	seq_printf(m, ",dmask=%04o", opts->fs_dmask);
947 	if (opts->allow_utime)
948 		seq_printf(m, ",allow_utime=%04o", opts->allow_utime);
949 	if (sbi->nls_disk)
950 		/* strip "cp" prefix from displayed option */
951 		seq_printf(m, ",codepage=%s", &sbi->nls_disk->charset[2]);
952 	if (isvfat) {
953 		if (sbi->nls_io)
954 			seq_printf(m, ",iocharset=%s", sbi->nls_io->charset);
955 
956 		switch (opts->shortname) {
957 		case VFAT_SFN_DISPLAY_WIN95 | VFAT_SFN_CREATE_WIN95:
958 			seq_puts(m, ",shortname=win95");
959 			break;
960 		case VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WINNT:
961 			seq_puts(m, ",shortname=winnt");
962 			break;
963 		case VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WIN95:
964 			seq_puts(m, ",shortname=mixed");
965 			break;
966 		case VFAT_SFN_DISPLAY_LOWER | VFAT_SFN_CREATE_WIN95:
967 			seq_puts(m, ",shortname=lower");
968 			break;
969 		default:
970 			seq_puts(m, ",shortname=unknown");
971 			break;
972 		}
973 	}
974 	if (opts->name_check != 'n')
975 		seq_printf(m, ",check=%c", opts->name_check);
976 	if (opts->usefree)
977 		seq_puts(m, ",usefree");
978 	if (opts->quiet)
979 		seq_puts(m, ",quiet");
980 	if (opts->showexec)
981 		seq_puts(m, ",showexec");
982 	if (opts->sys_immutable)
983 		seq_puts(m, ",sys_immutable");
984 	if (!isvfat) {
985 		if (opts->dotsOK)
986 			seq_puts(m, ",dotsOK=yes");
987 		if (opts->nocase)
988 			seq_puts(m, ",nocase");
989 	} else {
990 		if (opts->utf8)
991 			seq_puts(m, ",utf8");
992 		if (opts->unicode_xlate)
993 			seq_puts(m, ",uni_xlate");
994 		if (!opts->numtail)
995 			seq_puts(m, ",nonumtail");
996 		if (opts->rodir)
997 			seq_puts(m, ",rodir");
998 	}
999 	if (opts->flush)
1000 		seq_puts(m, ",flush");
1001 	if (opts->tz_set) {
1002 		if (opts->time_offset)
1003 			seq_printf(m, ",time_offset=%d", opts->time_offset);
1004 		else
1005 			seq_puts(m, ",tz=UTC");
1006 	}
1007 	if (opts->errors == FAT_ERRORS_CONT)
1008 		seq_puts(m, ",errors=continue");
1009 	else if (opts->errors == FAT_ERRORS_PANIC)
1010 		seq_puts(m, ",errors=panic");
1011 	else
1012 		seq_puts(m, ",errors=remount-ro");
1013 	if (opts->nfs == FAT_NFS_NOSTALE_RO)
1014 		seq_puts(m, ",nfs=nostale_ro");
1015 	else if (opts->nfs)
1016 		seq_puts(m, ",nfs=stale_rw");
1017 	if (opts->discard)
1018 		seq_puts(m, ",discard");
1019 	if (opts->dos1xfloppy)
1020 		seq_puts(m, ",dos1xfloppy");
1021 
1022 	return 0;
1023 }
1024 
1025 enum {
1026 	Opt_check_n, Opt_check_r, Opt_check_s, Opt_uid, Opt_gid,
1027 	Opt_umask, Opt_dmask, Opt_fmask, Opt_allow_utime, Opt_codepage,
1028 	Opt_usefree, Opt_nocase, Opt_quiet, Opt_showexec, Opt_debug,
1029 	Opt_immutable, Opt_dots, Opt_nodots,
1030 	Opt_charset, Opt_shortname_lower, Opt_shortname_win95,
1031 	Opt_shortname_winnt, Opt_shortname_mixed, Opt_utf8_no, Opt_utf8_yes,
1032 	Opt_uni_xl_no, Opt_uni_xl_yes, Opt_nonumtail_no, Opt_nonumtail_yes,
1033 	Opt_obsolete, Opt_flush, Opt_tz_utc, Opt_rodir, Opt_err_cont,
1034 	Opt_err_panic, Opt_err_ro, Opt_discard, Opt_nfs, Opt_time_offset,
1035 	Opt_nfs_stale_rw, Opt_nfs_nostale_ro, Opt_err, Opt_dos1xfloppy,
1036 };
1037 
1038 static const match_table_t fat_tokens = {
1039 	{Opt_check_r, "check=relaxed"},
1040 	{Opt_check_s, "check=strict"},
1041 	{Opt_check_n, "check=normal"},
1042 	{Opt_check_r, "check=r"},
1043 	{Opt_check_s, "check=s"},
1044 	{Opt_check_n, "check=n"},
1045 	{Opt_uid, "uid=%u"},
1046 	{Opt_gid, "gid=%u"},
1047 	{Opt_umask, "umask=%o"},
1048 	{Opt_dmask, "dmask=%o"},
1049 	{Opt_fmask, "fmask=%o"},
1050 	{Opt_allow_utime, "allow_utime=%o"},
1051 	{Opt_codepage, "codepage=%u"},
1052 	{Opt_usefree, "usefree"},
1053 	{Opt_nocase, "nocase"},
1054 	{Opt_quiet, "quiet"},
1055 	{Opt_showexec, "showexec"},
1056 	{Opt_debug, "debug"},
1057 	{Opt_immutable, "sys_immutable"},
1058 	{Opt_flush, "flush"},
1059 	{Opt_tz_utc, "tz=UTC"},
1060 	{Opt_time_offset, "time_offset=%d"},
1061 	{Opt_err_cont, "errors=continue"},
1062 	{Opt_err_panic, "errors=panic"},
1063 	{Opt_err_ro, "errors=remount-ro"},
1064 	{Opt_discard, "discard"},
1065 	{Opt_nfs_stale_rw, "nfs"},
1066 	{Opt_nfs_stale_rw, "nfs=stale_rw"},
1067 	{Opt_nfs_nostale_ro, "nfs=nostale_ro"},
1068 	{Opt_dos1xfloppy, "dos1xfloppy"},
1069 	{Opt_obsolete, "conv=binary"},
1070 	{Opt_obsolete, "conv=text"},
1071 	{Opt_obsolete, "conv=auto"},
1072 	{Opt_obsolete, "conv=b"},
1073 	{Opt_obsolete, "conv=t"},
1074 	{Opt_obsolete, "conv=a"},
1075 	{Opt_obsolete, "fat=%u"},
1076 	{Opt_obsolete, "blocksize=%u"},
1077 	{Opt_obsolete, "cvf_format=%20s"},
1078 	{Opt_obsolete, "cvf_options=%100s"},
1079 	{Opt_obsolete, "posix"},
1080 	{Opt_err, NULL},
1081 };
1082 static const match_table_t msdos_tokens = {
1083 	{Opt_nodots, "nodots"},
1084 	{Opt_nodots, "dotsOK=no"},
1085 	{Opt_dots, "dots"},
1086 	{Opt_dots, "dotsOK=yes"},
1087 	{Opt_err, NULL}
1088 };
1089 static const match_table_t vfat_tokens = {
1090 	{Opt_charset, "iocharset=%s"},
1091 	{Opt_shortname_lower, "shortname=lower"},
1092 	{Opt_shortname_win95, "shortname=win95"},
1093 	{Opt_shortname_winnt, "shortname=winnt"},
1094 	{Opt_shortname_mixed, "shortname=mixed"},
1095 	{Opt_utf8_no, "utf8=0"},		/* 0 or no or false */
1096 	{Opt_utf8_no, "utf8=no"},
1097 	{Opt_utf8_no, "utf8=false"},
1098 	{Opt_utf8_yes, "utf8=1"},		/* empty or 1 or yes or true */
1099 	{Opt_utf8_yes, "utf8=yes"},
1100 	{Opt_utf8_yes, "utf8=true"},
1101 	{Opt_utf8_yes, "utf8"},
1102 	{Opt_uni_xl_no, "uni_xlate=0"},		/* 0 or no or false */
1103 	{Opt_uni_xl_no, "uni_xlate=no"},
1104 	{Opt_uni_xl_no, "uni_xlate=false"},
1105 	{Opt_uni_xl_yes, "uni_xlate=1"},	/* empty or 1 or yes or true */
1106 	{Opt_uni_xl_yes, "uni_xlate=yes"},
1107 	{Opt_uni_xl_yes, "uni_xlate=true"},
1108 	{Opt_uni_xl_yes, "uni_xlate"},
1109 	{Opt_nonumtail_no, "nonumtail=0"},	/* 0 or no or false */
1110 	{Opt_nonumtail_no, "nonumtail=no"},
1111 	{Opt_nonumtail_no, "nonumtail=false"},
1112 	{Opt_nonumtail_yes, "nonumtail=1"},	/* empty or 1 or yes or true */
1113 	{Opt_nonumtail_yes, "nonumtail=yes"},
1114 	{Opt_nonumtail_yes, "nonumtail=true"},
1115 	{Opt_nonumtail_yes, "nonumtail"},
1116 	{Opt_rodir, "rodir"},
1117 	{Opt_err, NULL}
1118 };
1119 
1120 static int parse_options(struct super_block *sb, char *options, int is_vfat,
1121 			 int silent, int *debug, struct fat_mount_options *opts)
1122 {
1123 	char *p;
1124 	substring_t args[MAX_OPT_ARGS];
1125 	int option;
1126 	char *iocharset;
1127 
1128 	opts->isvfat = is_vfat;
1129 
1130 	opts->fs_uid = current_uid();
1131 	opts->fs_gid = current_gid();
1132 	opts->fs_fmask = opts->fs_dmask = current_umask();
1133 	opts->allow_utime = -1;
1134 	opts->codepage = fat_default_codepage;
1135 	fat_reset_iocharset(opts);
1136 	if (is_vfat) {
1137 		opts->shortname = VFAT_SFN_DISPLAY_WINNT|VFAT_SFN_CREATE_WIN95;
1138 		opts->rodir = 0;
1139 	} else {
1140 		opts->shortname = 0;
1141 		opts->rodir = 1;
1142 	}
1143 	opts->name_check = 'n';
1144 	opts->quiet = opts->showexec = opts->sys_immutable = opts->dotsOK =  0;
1145 	opts->unicode_xlate = 0;
1146 	opts->numtail = 1;
1147 	opts->usefree = opts->nocase = 0;
1148 	opts->tz_set = 0;
1149 	opts->nfs = 0;
1150 	opts->errors = FAT_ERRORS_RO;
1151 	*debug = 0;
1152 
1153 	opts->utf8 = IS_ENABLED(CONFIG_FAT_DEFAULT_UTF8) && is_vfat;
1154 
1155 	if (!options)
1156 		goto out;
1157 
1158 	while ((p = strsep(&options, ",")) != NULL) {
1159 		int token;
1160 		if (!*p)
1161 			continue;
1162 
1163 		token = match_token(p, fat_tokens, args);
1164 		if (token == Opt_err) {
1165 			if (is_vfat)
1166 				token = match_token(p, vfat_tokens, args);
1167 			else
1168 				token = match_token(p, msdos_tokens, args);
1169 		}
1170 		switch (token) {
1171 		case Opt_check_s:
1172 			opts->name_check = 's';
1173 			break;
1174 		case Opt_check_r:
1175 			opts->name_check = 'r';
1176 			break;
1177 		case Opt_check_n:
1178 			opts->name_check = 'n';
1179 			break;
1180 		case Opt_usefree:
1181 			opts->usefree = 1;
1182 			break;
1183 		case Opt_nocase:
1184 			if (!is_vfat)
1185 				opts->nocase = 1;
1186 			else {
1187 				/* for backward compatibility */
1188 				opts->shortname = VFAT_SFN_DISPLAY_WIN95
1189 					| VFAT_SFN_CREATE_WIN95;
1190 			}
1191 			break;
1192 		case Opt_quiet:
1193 			opts->quiet = 1;
1194 			break;
1195 		case Opt_showexec:
1196 			opts->showexec = 1;
1197 			break;
1198 		case Opt_debug:
1199 			*debug = 1;
1200 			break;
1201 		case Opt_immutable:
1202 			opts->sys_immutable = 1;
1203 			break;
1204 		case Opt_uid:
1205 			if (match_int(&args[0], &option))
1206 				return -EINVAL;
1207 			opts->fs_uid = make_kuid(current_user_ns(), option);
1208 			if (!uid_valid(opts->fs_uid))
1209 				return -EINVAL;
1210 			break;
1211 		case Opt_gid:
1212 			if (match_int(&args[0], &option))
1213 				return -EINVAL;
1214 			opts->fs_gid = make_kgid(current_user_ns(), option);
1215 			if (!gid_valid(opts->fs_gid))
1216 				return -EINVAL;
1217 			break;
1218 		case Opt_umask:
1219 			if (match_octal(&args[0], &option))
1220 				return -EINVAL;
1221 			opts->fs_fmask = opts->fs_dmask = option;
1222 			break;
1223 		case Opt_dmask:
1224 			if (match_octal(&args[0], &option))
1225 				return -EINVAL;
1226 			opts->fs_dmask = option;
1227 			break;
1228 		case Opt_fmask:
1229 			if (match_octal(&args[0], &option))
1230 				return -EINVAL;
1231 			opts->fs_fmask = option;
1232 			break;
1233 		case Opt_allow_utime:
1234 			if (match_octal(&args[0], &option))
1235 				return -EINVAL;
1236 			opts->allow_utime = option & (S_IWGRP | S_IWOTH);
1237 			break;
1238 		case Opt_codepage:
1239 			if (match_int(&args[0], &option))
1240 				return -EINVAL;
1241 			opts->codepage = option;
1242 			break;
1243 		case Opt_flush:
1244 			opts->flush = 1;
1245 			break;
1246 		case Opt_time_offset:
1247 			if (match_int(&args[0], &option))
1248 				return -EINVAL;
1249 			/*
1250 			 * GMT+-12 zones may have DST corrections so at least
1251 			 * 13 hours difference is needed. Make the limit 24
1252 			 * just in case someone invents something unusual.
1253 			 */
1254 			if (option < -24 * 60 || option > 24 * 60)
1255 				return -EINVAL;
1256 			opts->tz_set = 1;
1257 			opts->time_offset = option;
1258 			break;
1259 		case Opt_tz_utc:
1260 			opts->tz_set = 1;
1261 			opts->time_offset = 0;
1262 			break;
1263 		case Opt_err_cont:
1264 			opts->errors = FAT_ERRORS_CONT;
1265 			break;
1266 		case Opt_err_panic:
1267 			opts->errors = FAT_ERRORS_PANIC;
1268 			break;
1269 		case Opt_err_ro:
1270 			opts->errors = FAT_ERRORS_RO;
1271 			break;
1272 		case Opt_nfs_stale_rw:
1273 			opts->nfs = FAT_NFS_STALE_RW;
1274 			break;
1275 		case Opt_nfs_nostale_ro:
1276 			opts->nfs = FAT_NFS_NOSTALE_RO;
1277 			break;
1278 		case Opt_dos1xfloppy:
1279 			opts->dos1xfloppy = 1;
1280 			break;
1281 
1282 		/* msdos specific */
1283 		case Opt_dots:
1284 			opts->dotsOK = 1;
1285 			break;
1286 		case Opt_nodots:
1287 			opts->dotsOK = 0;
1288 			break;
1289 
1290 		/* vfat specific */
1291 		case Opt_charset:
1292 			fat_reset_iocharset(opts);
1293 			iocharset = match_strdup(&args[0]);
1294 			if (!iocharset)
1295 				return -ENOMEM;
1296 			opts->iocharset = iocharset;
1297 			break;
1298 		case Opt_shortname_lower:
1299 			opts->shortname = VFAT_SFN_DISPLAY_LOWER
1300 					| VFAT_SFN_CREATE_WIN95;
1301 			break;
1302 		case Opt_shortname_win95:
1303 			opts->shortname = VFAT_SFN_DISPLAY_WIN95
1304 					| VFAT_SFN_CREATE_WIN95;
1305 			break;
1306 		case Opt_shortname_winnt:
1307 			opts->shortname = VFAT_SFN_DISPLAY_WINNT
1308 					| VFAT_SFN_CREATE_WINNT;
1309 			break;
1310 		case Opt_shortname_mixed:
1311 			opts->shortname = VFAT_SFN_DISPLAY_WINNT
1312 					| VFAT_SFN_CREATE_WIN95;
1313 			break;
1314 		case Opt_utf8_no:		/* 0 or no or false */
1315 			opts->utf8 = 0;
1316 			break;
1317 		case Opt_utf8_yes:		/* empty or 1 or yes or true */
1318 			opts->utf8 = 1;
1319 			break;
1320 		case Opt_uni_xl_no:		/* 0 or no or false */
1321 			opts->unicode_xlate = 0;
1322 			break;
1323 		case Opt_uni_xl_yes:		/* empty or 1 or yes or true */
1324 			opts->unicode_xlate = 1;
1325 			break;
1326 		case Opt_nonumtail_no:		/* 0 or no or false */
1327 			opts->numtail = 1;	/* negated option */
1328 			break;
1329 		case Opt_nonumtail_yes:		/* empty or 1 or yes or true */
1330 			opts->numtail = 0;	/* negated option */
1331 			break;
1332 		case Opt_rodir:
1333 			opts->rodir = 1;
1334 			break;
1335 		case Opt_discard:
1336 			opts->discard = 1;
1337 			break;
1338 
1339 		/* obsolete mount options */
1340 		case Opt_obsolete:
1341 			fat_msg(sb, KERN_INFO, "\"%s\" option is obsolete, "
1342 			       "not supported now", p);
1343 			break;
1344 		/* unknown option */
1345 		default:
1346 			if (!silent) {
1347 				fat_msg(sb, KERN_ERR,
1348 				       "Unrecognized mount option \"%s\" "
1349 				       "or missing value", p);
1350 			}
1351 			return -EINVAL;
1352 		}
1353 	}
1354 
1355 out:
1356 	/* UTF-8 doesn't provide FAT semantics */
1357 	if (!strcmp(opts->iocharset, "utf8")) {
1358 		fat_msg(sb, KERN_WARNING, "utf8 is not a recommended IO charset"
1359 		       " for FAT filesystems, filesystem will be "
1360 		       "case sensitive!");
1361 	}
1362 
1363 	/* If user doesn't specify allow_utime, it's initialized from dmask. */
1364 	if (opts->allow_utime == (unsigned short)-1)
1365 		opts->allow_utime = ~opts->fs_dmask & (S_IWGRP | S_IWOTH);
1366 	if (opts->unicode_xlate)
1367 		opts->utf8 = 0;
1368 	if (opts->nfs == FAT_NFS_NOSTALE_RO) {
1369 		sb->s_flags |= SB_RDONLY;
1370 		sb->s_export_op = &fat_export_ops_nostale;
1371 	}
1372 
1373 	return 0;
1374 }
1375 
1376 static void fat_dummy_inode_init(struct inode *inode)
1377 {
1378 	/* Initialize this dummy inode to work as no-op. */
1379 	MSDOS_I(inode)->mmu_private = 0;
1380 	MSDOS_I(inode)->i_start = 0;
1381 	MSDOS_I(inode)->i_logstart = 0;
1382 	MSDOS_I(inode)->i_attrs = 0;
1383 	MSDOS_I(inode)->i_pos = 0;
1384 }
1385 
1386 static int fat_read_root(struct inode *inode)
1387 {
1388 	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
1389 	int error;
1390 
1391 	MSDOS_I(inode)->i_pos = MSDOS_ROOT_INO;
1392 	inode->i_uid = sbi->options.fs_uid;
1393 	inode->i_gid = sbi->options.fs_gid;
1394 	inode_inc_iversion(inode);
1395 	inode->i_generation = 0;
1396 	inode->i_mode = fat_make_mode(sbi, ATTR_DIR, S_IRWXUGO);
1397 	inode->i_op = sbi->dir_ops;
1398 	inode->i_fop = &fat_dir_operations;
1399 	if (is_fat32(sbi)) {
1400 		MSDOS_I(inode)->i_start = sbi->root_cluster;
1401 		error = fat_calc_dir_size(inode);
1402 		if (error < 0)
1403 			return error;
1404 	} else {
1405 		MSDOS_I(inode)->i_start = 0;
1406 		inode->i_size = sbi->dir_entries * sizeof(struct msdos_dir_entry);
1407 	}
1408 	inode->i_blocks = ((inode->i_size + (sbi->cluster_size - 1))
1409 			   & ~((loff_t)sbi->cluster_size - 1)) >> 9;
1410 	MSDOS_I(inode)->i_logstart = 0;
1411 	MSDOS_I(inode)->mmu_private = inode->i_size;
1412 
1413 	fat_save_attrs(inode, ATTR_DIR);
1414 	inode->i_mtime.tv_sec = inode->i_atime.tv_sec = inode->i_ctime.tv_sec = 0;
1415 	inode->i_mtime.tv_nsec = inode->i_atime.tv_nsec = inode->i_ctime.tv_nsec = 0;
1416 	set_nlink(inode, fat_subdirs(inode)+2);
1417 
1418 	return 0;
1419 }
1420 
1421 static unsigned long calc_fat_clusters(struct super_block *sb)
1422 {
1423 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
1424 
1425 	/* Divide first to avoid overflow */
1426 	if (!is_fat12(sbi)) {
1427 		unsigned long ent_per_sec = sb->s_blocksize * 8 / sbi->fat_bits;
1428 		return ent_per_sec * sbi->fat_length;
1429 	}
1430 
1431 	return sbi->fat_length * sb->s_blocksize * 8 / sbi->fat_bits;
1432 }
1433 
1434 static bool fat_bpb_is_zero(struct fat_boot_sector *b)
1435 {
1436 	if (get_unaligned_le16(&b->sector_size))
1437 		return false;
1438 	if (b->sec_per_clus)
1439 		return false;
1440 	if (b->reserved)
1441 		return false;
1442 	if (b->fats)
1443 		return false;
1444 	if (get_unaligned_le16(&b->dir_entries))
1445 		return false;
1446 	if (get_unaligned_le16(&b->sectors))
1447 		return false;
1448 	if (b->media)
1449 		return false;
1450 	if (b->fat_length)
1451 		return false;
1452 	if (b->secs_track)
1453 		return false;
1454 	if (b->heads)
1455 		return false;
1456 	return true;
1457 }
1458 
1459 static int fat_read_bpb(struct super_block *sb, struct fat_boot_sector *b,
1460 	int silent, struct fat_bios_param_block *bpb)
1461 {
1462 	int error = -EINVAL;
1463 
1464 	/* Read in BPB ... */
1465 	memset(bpb, 0, sizeof(*bpb));
1466 	bpb->fat_sector_size = get_unaligned_le16(&b->sector_size);
1467 	bpb->fat_sec_per_clus = b->sec_per_clus;
1468 	bpb->fat_reserved = le16_to_cpu(b->reserved);
1469 	bpb->fat_fats = b->fats;
1470 	bpb->fat_dir_entries = get_unaligned_le16(&b->dir_entries);
1471 	bpb->fat_sectors = get_unaligned_le16(&b->sectors);
1472 	bpb->fat_fat_length = le16_to_cpu(b->fat_length);
1473 	bpb->fat_total_sect = le32_to_cpu(b->total_sect);
1474 
1475 	bpb->fat16_state = b->fat16.state;
1476 	bpb->fat16_vol_id = get_unaligned_le32(b->fat16.vol_id);
1477 
1478 	bpb->fat32_length = le32_to_cpu(b->fat32.length);
1479 	bpb->fat32_root_cluster = le32_to_cpu(b->fat32.root_cluster);
1480 	bpb->fat32_info_sector = le16_to_cpu(b->fat32.info_sector);
1481 	bpb->fat32_state = b->fat32.state;
1482 	bpb->fat32_vol_id = get_unaligned_le32(b->fat32.vol_id);
1483 
1484 	/* Validate this looks like a FAT filesystem BPB */
1485 	if (!bpb->fat_reserved) {
1486 		if (!silent)
1487 			fat_msg(sb, KERN_ERR,
1488 				"bogus number of reserved sectors");
1489 		goto out;
1490 	}
1491 	if (!bpb->fat_fats) {
1492 		if (!silent)
1493 			fat_msg(sb, KERN_ERR, "bogus number of FAT structure");
1494 		goto out;
1495 	}
1496 
1497 	/*
1498 	 * Earlier we checked here that b->secs_track and b->head are nonzero,
1499 	 * but it turns out valid FAT filesystems can have zero there.
1500 	 */
1501 
1502 	if (!fat_valid_media(b->media)) {
1503 		if (!silent)
1504 			fat_msg(sb, KERN_ERR, "invalid media value (0x%02x)",
1505 				(unsigned)b->media);
1506 		goto out;
1507 	}
1508 
1509 	if (!is_power_of_2(bpb->fat_sector_size)
1510 	    || (bpb->fat_sector_size < 512)
1511 	    || (bpb->fat_sector_size > 4096)) {
1512 		if (!silent)
1513 			fat_msg(sb, KERN_ERR, "bogus logical sector size %u",
1514 			       (unsigned)bpb->fat_sector_size);
1515 		goto out;
1516 	}
1517 
1518 	if (!is_power_of_2(bpb->fat_sec_per_clus)) {
1519 		if (!silent)
1520 			fat_msg(sb, KERN_ERR, "bogus sectors per cluster %u",
1521 				(unsigned)bpb->fat_sec_per_clus);
1522 		goto out;
1523 	}
1524 
1525 	error = 0;
1526 
1527 out:
1528 	return error;
1529 }
1530 
1531 static int fat_read_static_bpb(struct super_block *sb,
1532 	struct fat_boot_sector *b, int silent,
1533 	struct fat_bios_param_block *bpb)
1534 {
1535 	static const char *notdos1x = "This doesn't look like a DOS 1.x volume";
1536 
1537 	struct fat_floppy_defaults *fdefaults = NULL;
1538 	int error = -EINVAL;
1539 	sector_t bd_sects;
1540 	unsigned i;
1541 
1542 	bd_sects = i_size_read(sb->s_bdev->bd_inode) / SECTOR_SIZE;
1543 
1544 	/* 16-bit DOS 1.x reliably wrote bootstrap short-jmp code */
1545 	if (b->ignored[0] != 0xeb || b->ignored[2] != 0x90) {
1546 		if (!silent)
1547 			fat_msg(sb, KERN_ERR,
1548 				"%s; no bootstrapping code", notdos1x);
1549 		goto out;
1550 	}
1551 
1552 	/*
1553 	 * If any value in this region is non-zero, it isn't archaic
1554 	 * DOS.
1555 	 */
1556 	if (!fat_bpb_is_zero(b)) {
1557 		if (!silent)
1558 			fat_msg(sb, KERN_ERR,
1559 				"%s; DOS 2.x BPB is non-zero", notdos1x);
1560 		goto out;
1561 	}
1562 
1563 	for (i = 0; i < ARRAY_SIZE(floppy_defaults); i++) {
1564 		if (floppy_defaults[i].nr_sectors == bd_sects) {
1565 			fdefaults = &floppy_defaults[i];
1566 			break;
1567 		}
1568 	}
1569 
1570 	if (fdefaults == NULL) {
1571 		if (!silent)
1572 			fat_msg(sb, KERN_WARNING,
1573 				"This looks like a DOS 1.x volume, but isn't a recognized floppy size (%llu sectors)",
1574 				(u64)bd_sects);
1575 		goto out;
1576 	}
1577 
1578 	if (!silent)
1579 		fat_msg(sb, KERN_INFO,
1580 			"This looks like a DOS 1.x volume; assuming default BPB values");
1581 
1582 	memset(bpb, 0, sizeof(*bpb));
1583 	bpb->fat_sector_size = SECTOR_SIZE;
1584 	bpb->fat_sec_per_clus = fdefaults->sec_per_clus;
1585 	bpb->fat_reserved = 1;
1586 	bpb->fat_fats = 2;
1587 	bpb->fat_dir_entries = fdefaults->dir_entries;
1588 	bpb->fat_sectors = fdefaults->nr_sectors;
1589 	bpb->fat_fat_length = fdefaults->fat_length;
1590 
1591 	error = 0;
1592 
1593 out:
1594 	return error;
1595 }
1596 
1597 /*
1598  * Read the super block of an MS-DOS FS.
1599  */
1600 int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat,
1601 		   void (*setup)(struct super_block *))
1602 {
1603 	struct inode *root_inode = NULL, *fat_inode = NULL;
1604 	struct inode *fsinfo_inode = NULL;
1605 	struct buffer_head *bh;
1606 	struct fat_bios_param_block bpb;
1607 	struct msdos_sb_info *sbi;
1608 	u16 logical_sector_size;
1609 	u32 total_sectors, total_clusters, fat_clusters, rootdir_sectors;
1610 	int debug;
1611 	long error;
1612 	char buf[50];
1613 
1614 	/*
1615 	 * GFP_KERNEL is ok here, because while we do hold the
1616 	 * superblock lock, memory pressure can't call back into
1617 	 * the filesystem, since we're only just about to mount
1618 	 * it and have no inodes etc active!
1619 	 */
1620 	sbi = kzalloc(sizeof(struct msdos_sb_info), GFP_KERNEL);
1621 	if (!sbi)
1622 		return -ENOMEM;
1623 	sb->s_fs_info = sbi;
1624 
1625 	sb->s_flags |= SB_NODIRATIME;
1626 	sb->s_magic = MSDOS_SUPER_MAGIC;
1627 	sb->s_op = &fat_sops;
1628 	sb->s_export_op = &fat_export_ops;
1629 	/*
1630 	 * fat timestamps are complex and truncated by fat itself, so
1631 	 * we set 1 here to be fast
1632 	 */
1633 	sb->s_time_gran = 1;
1634 	mutex_init(&sbi->nfs_build_inode_lock);
1635 	ratelimit_state_init(&sbi->ratelimit, DEFAULT_RATELIMIT_INTERVAL,
1636 			     DEFAULT_RATELIMIT_BURST);
1637 
1638 	error = parse_options(sb, data, isvfat, silent, &debug, &sbi->options);
1639 	if (error)
1640 		goto out_fail;
1641 
1642 	setup(sb); /* flavour-specific stuff that needs options */
1643 
1644 	error = -EIO;
1645 	sb_min_blocksize(sb, 512);
1646 	bh = sb_bread(sb, 0);
1647 	if (bh == NULL) {
1648 		fat_msg(sb, KERN_ERR, "unable to read boot sector");
1649 		goto out_fail;
1650 	}
1651 
1652 	error = fat_read_bpb(sb, (struct fat_boot_sector *)bh->b_data, silent,
1653 		&bpb);
1654 	if (error == -EINVAL && sbi->options.dos1xfloppy)
1655 		error = fat_read_static_bpb(sb,
1656 			(struct fat_boot_sector *)bh->b_data, silent, &bpb);
1657 	brelse(bh);
1658 
1659 	if (error == -EINVAL)
1660 		goto out_invalid;
1661 	else if (error)
1662 		goto out_fail;
1663 
1664 	logical_sector_size = bpb.fat_sector_size;
1665 	sbi->sec_per_clus = bpb.fat_sec_per_clus;
1666 
1667 	error = -EIO;
1668 	if (logical_sector_size < sb->s_blocksize) {
1669 		fat_msg(sb, KERN_ERR, "logical sector size too small for device"
1670 		       " (logical sector size = %u)", logical_sector_size);
1671 		goto out_fail;
1672 	}
1673 
1674 	if (logical_sector_size > sb->s_blocksize) {
1675 		struct buffer_head *bh_resize;
1676 
1677 		if (!sb_set_blocksize(sb, logical_sector_size)) {
1678 			fat_msg(sb, KERN_ERR, "unable to set blocksize %u",
1679 			       logical_sector_size);
1680 			goto out_fail;
1681 		}
1682 
1683 		/* Verify that the larger boot sector is fully readable */
1684 		bh_resize = sb_bread(sb, 0);
1685 		if (bh_resize == NULL) {
1686 			fat_msg(sb, KERN_ERR, "unable to read boot sector"
1687 			       " (logical sector size = %lu)",
1688 			       sb->s_blocksize);
1689 			goto out_fail;
1690 		}
1691 		brelse(bh_resize);
1692 	}
1693 
1694 	mutex_init(&sbi->s_lock);
1695 	sbi->cluster_size = sb->s_blocksize * sbi->sec_per_clus;
1696 	sbi->cluster_bits = ffs(sbi->cluster_size) - 1;
1697 	sbi->fats = bpb.fat_fats;
1698 	sbi->fat_bits = 0;		/* Don't know yet */
1699 	sbi->fat_start = bpb.fat_reserved;
1700 	sbi->fat_length = bpb.fat_fat_length;
1701 	sbi->root_cluster = 0;
1702 	sbi->free_clusters = -1;	/* Don't know yet */
1703 	sbi->free_clus_valid = 0;
1704 	sbi->prev_free = FAT_START_ENT;
1705 	sb->s_maxbytes = 0xffffffff;
1706 
1707 	if (!sbi->fat_length && bpb.fat32_length) {
1708 		struct fat_boot_fsinfo *fsinfo;
1709 		struct buffer_head *fsinfo_bh;
1710 
1711 		/* Must be FAT32 */
1712 		sbi->fat_bits = 32;
1713 		sbi->fat_length = bpb.fat32_length;
1714 		sbi->root_cluster = bpb.fat32_root_cluster;
1715 
1716 		/* MC - if info_sector is 0, don't multiply by 0 */
1717 		sbi->fsinfo_sector = bpb.fat32_info_sector;
1718 		if (sbi->fsinfo_sector == 0)
1719 			sbi->fsinfo_sector = 1;
1720 
1721 		fsinfo_bh = sb_bread(sb, sbi->fsinfo_sector);
1722 		if (fsinfo_bh == NULL) {
1723 			fat_msg(sb, KERN_ERR, "bread failed, FSINFO block"
1724 			       " (sector = %lu)", sbi->fsinfo_sector);
1725 			goto out_fail;
1726 		}
1727 
1728 		fsinfo = (struct fat_boot_fsinfo *)fsinfo_bh->b_data;
1729 		if (!IS_FSINFO(fsinfo)) {
1730 			fat_msg(sb, KERN_WARNING, "Invalid FSINFO signature: "
1731 			       "0x%08x, 0x%08x (sector = %lu)",
1732 			       le32_to_cpu(fsinfo->signature1),
1733 			       le32_to_cpu(fsinfo->signature2),
1734 			       sbi->fsinfo_sector);
1735 		} else {
1736 			if (sbi->options.usefree)
1737 				sbi->free_clus_valid = 1;
1738 			sbi->free_clusters = le32_to_cpu(fsinfo->free_clusters);
1739 			sbi->prev_free = le32_to_cpu(fsinfo->next_cluster);
1740 		}
1741 
1742 		brelse(fsinfo_bh);
1743 	}
1744 
1745 	/* interpret volume ID as a little endian 32 bit integer */
1746 	if (is_fat32(sbi))
1747 		sbi->vol_id = bpb.fat32_vol_id;
1748 	else /* fat 16 or 12 */
1749 		sbi->vol_id = bpb.fat16_vol_id;
1750 
1751 	sbi->dir_per_block = sb->s_blocksize / sizeof(struct msdos_dir_entry);
1752 	sbi->dir_per_block_bits = ffs(sbi->dir_per_block) - 1;
1753 
1754 	sbi->dir_start = sbi->fat_start + sbi->fats * sbi->fat_length;
1755 	sbi->dir_entries = bpb.fat_dir_entries;
1756 	if (sbi->dir_entries & (sbi->dir_per_block - 1)) {
1757 		if (!silent)
1758 			fat_msg(sb, KERN_ERR, "bogus number of directory entries"
1759 			       " (%u)", sbi->dir_entries);
1760 		goto out_invalid;
1761 	}
1762 
1763 	rootdir_sectors = sbi->dir_entries
1764 		* sizeof(struct msdos_dir_entry) / sb->s_blocksize;
1765 	sbi->data_start = sbi->dir_start + rootdir_sectors;
1766 	total_sectors = bpb.fat_sectors;
1767 	if (total_sectors == 0)
1768 		total_sectors = bpb.fat_total_sect;
1769 
1770 	total_clusters = (total_sectors - sbi->data_start) / sbi->sec_per_clus;
1771 
1772 	if (!is_fat32(sbi))
1773 		sbi->fat_bits = (total_clusters > MAX_FAT12) ? 16 : 12;
1774 
1775 	/* some OSes set FAT_STATE_DIRTY and clean it on unmount. */
1776 	if (is_fat32(sbi))
1777 		sbi->dirty = bpb.fat32_state & FAT_STATE_DIRTY;
1778 	else /* fat 16 or 12 */
1779 		sbi->dirty = bpb.fat16_state & FAT_STATE_DIRTY;
1780 
1781 	/* check that FAT table does not overflow */
1782 	fat_clusters = calc_fat_clusters(sb);
1783 	total_clusters = min(total_clusters, fat_clusters - FAT_START_ENT);
1784 	if (total_clusters > max_fat(sb)) {
1785 		if (!silent)
1786 			fat_msg(sb, KERN_ERR, "count of clusters too big (%u)",
1787 			       total_clusters);
1788 		goto out_invalid;
1789 	}
1790 
1791 	sbi->max_cluster = total_clusters + FAT_START_ENT;
1792 	/* check the free_clusters, it's not necessarily correct */
1793 	if (sbi->free_clusters != -1 && sbi->free_clusters > total_clusters)
1794 		sbi->free_clusters = -1;
1795 	/* check the prev_free, it's not necessarily correct */
1796 	sbi->prev_free %= sbi->max_cluster;
1797 	if (sbi->prev_free < FAT_START_ENT)
1798 		sbi->prev_free = FAT_START_ENT;
1799 
1800 	/* set up enough so that it can read an inode */
1801 	fat_hash_init(sb);
1802 	dir_hash_init(sb);
1803 	fat_ent_access_init(sb);
1804 
1805 	/*
1806 	 * The low byte of the first FAT entry must have the same value as
1807 	 * the media field of the boot sector. But in real world, too many
1808 	 * devices are writing wrong values. So, removed that validity check.
1809 	 *
1810 	 * The removed check compared the first FAT entry to a value dependent
1811 	 * on the media field like this:
1812 	 * == (0x0F00 | media), for FAT12
1813 	 * == (0XFF00 | media), for FAT16
1814 	 * == (0x0FFFFF | media), for FAT32
1815 	 */
1816 
1817 	error = -EINVAL;
1818 	sprintf(buf, "cp%d", sbi->options.codepage);
1819 	sbi->nls_disk = load_nls(buf);
1820 	if (!sbi->nls_disk) {
1821 		fat_msg(sb, KERN_ERR, "codepage %s not found", buf);
1822 		goto out_fail;
1823 	}
1824 
1825 	/* FIXME: utf8 is using iocharset for upper/lower conversion */
1826 	if (sbi->options.isvfat) {
1827 		sbi->nls_io = load_nls(sbi->options.iocharset);
1828 		if (!sbi->nls_io) {
1829 			fat_msg(sb, KERN_ERR, "IO charset %s not found",
1830 			       sbi->options.iocharset);
1831 			goto out_fail;
1832 		}
1833 	}
1834 
1835 	error = -ENOMEM;
1836 	fat_inode = new_inode(sb);
1837 	if (!fat_inode)
1838 		goto out_fail;
1839 	fat_dummy_inode_init(fat_inode);
1840 	sbi->fat_inode = fat_inode;
1841 
1842 	fsinfo_inode = new_inode(sb);
1843 	if (!fsinfo_inode)
1844 		goto out_fail;
1845 	fat_dummy_inode_init(fsinfo_inode);
1846 	fsinfo_inode->i_ino = MSDOS_FSINFO_INO;
1847 	sbi->fsinfo_inode = fsinfo_inode;
1848 	insert_inode_hash(fsinfo_inode);
1849 
1850 	root_inode = new_inode(sb);
1851 	if (!root_inode)
1852 		goto out_fail;
1853 	root_inode->i_ino = MSDOS_ROOT_INO;
1854 	inode_set_iversion(root_inode, 1);
1855 	error = fat_read_root(root_inode);
1856 	if (error < 0) {
1857 		iput(root_inode);
1858 		goto out_fail;
1859 	}
1860 	error = -ENOMEM;
1861 	insert_inode_hash(root_inode);
1862 	fat_attach(root_inode, 0);
1863 	sb->s_root = d_make_root(root_inode);
1864 	if (!sb->s_root) {
1865 		fat_msg(sb, KERN_ERR, "get root inode failed");
1866 		goto out_fail;
1867 	}
1868 
1869 	if (sbi->options.discard) {
1870 		struct request_queue *q = bdev_get_queue(sb->s_bdev);
1871 		if (!blk_queue_discard(q))
1872 			fat_msg(sb, KERN_WARNING,
1873 					"mounting with \"discard\" option, but "
1874 					"the device does not support discard");
1875 	}
1876 
1877 	fat_set_state(sb, 1, 0);
1878 	return 0;
1879 
1880 out_invalid:
1881 	error = -EINVAL;
1882 	if (!silent)
1883 		fat_msg(sb, KERN_INFO, "Can't find a valid FAT filesystem");
1884 
1885 out_fail:
1886 	if (fsinfo_inode)
1887 		iput(fsinfo_inode);
1888 	if (fat_inode)
1889 		iput(fat_inode);
1890 	unload_nls(sbi->nls_io);
1891 	unload_nls(sbi->nls_disk);
1892 	fat_reset_iocharset(&sbi->options);
1893 	sb->s_fs_info = NULL;
1894 	kfree(sbi);
1895 	return error;
1896 }
1897 
1898 EXPORT_SYMBOL_GPL(fat_fill_super);
1899 
1900 /*
1901  * helper function for fat_flush_inodes.  This writes both the inode
1902  * and the file data blocks, waiting for in flight data blocks before
1903  * the start of the call.  It does not wait for any io started
1904  * during the call
1905  */
1906 static int writeback_inode(struct inode *inode)
1907 {
1908 
1909 	int ret;
1910 
1911 	/* if we used wait=1, sync_inode_metadata waits for the io for the
1912 	* inode to finish.  So wait=0 is sent down to sync_inode_metadata
1913 	* and filemap_fdatawrite is used for the data blocks
1914 	*/
1915 	ret = sync_inode_metadata(inode, 0);
1916 	if (!ret)
1917 		ret = filemap_fdatawrite(inode->i_mapping);
1918 	return ret;
1919 }
1920 
1921 /*
1922  * write data and metadata corresponding to i1 and i2.  The io is
1923  * started but we do not wait for any of it to finish.
1924  *
1925  * filemap_flush is used for the block device, so if there is a dirty
1926  * page for a block already in flight, we will not wait and start the
1927  * io over again
1928  */
1929 int fat_flush_inodes(struct super_block *sb, struct inode *i1, struct inode *i2)
1930 {
1931 	int ret = 0;
1932 	if (!MSDOS_SB(sb)->options.flush)
1933 		return 0;
1934 	if (i1)
1935 		ret = writeback_inode(i1);
1936 	if (!ret && i2)
1937 		ret = writeback_inode(i2);
1938 	if (!ret) {
1939 		struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping;
1940 		ret = filemap_flush(mapping);
1941 	}
1942 	return ret;
1943 }
1944 EXPORT_SYMBOL_GPL(fat_flush_inodes);
1945 
1946 static int __init init_fat_fs(void)
1947 {
1948 	int err;
1949 
1950 	err = fat_cache_init();
1951 	if (err)
1952 		return err;
1953 
1954 	err = fat_init_inodecache();
1955 	if (err)
1956 		goto failed;
1957 
1958 	return 0;
1959 
1960 failed:
1961 	fat_cache_destroy();
1962 	return err;
1963 }
1964 
1965 static void __exit exit_fat_fs(void)
1966 {
1967 	fat_cache_destroy();
1968 	fat_destroy_inodecache();
1969 }
1970 
1971 module_init(init_fat_fs)
1972 module_exit(exit_fat_fs)
1973 
1974 MODULE_LICENSE("GPL");
1975