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 
fat_add_cluster(struct inode * inode)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 
__fat_get_block(struct inode * inode,sector_t iblock,unsigned long * max_blocks,struct buffer_head * bh_result,int create)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 
fat_get_block(struct inode * inode,sector_t iblock,struct buffer_head * bh_result,int create)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 
fat_writepage(struct page * page,struct writeback_control * wbc)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 
fat_writepages(struct address_space * mapping,struct writeback_control * wbc)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 
fat_readpage(struct file * file,struct page * page)201 static int fat_readpage(struct file *file, struct page *page)
202 {
203 	return mpage_readpage(page, fat_get_block);
204 }
205 
fat_readpages(struct file * file,struct address_space * mapping,struct list_head * pages,unsigned nr_pages)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 
fat_write_failed(struct address_space * mapping,loff_t to)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 
fat_write_begin(struct file * file,struct address_space * mapping,loff_t pos,unsigned len,unsigned flags,struct page ** pagep,void ** fsdata)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 
fat_write_end(struct file * file,struct address_space * mapping,loff_t pos,unsigned len,unsigned copied,struct page * pagep,void * fsdata)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 		inode->i_mtime = inode->i_ctime = current_time(inode);
248 		MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
249 		mark_inode_dirty(inode);
250 	}
251 	return err;
252 }
253 
fat_direct_IO(struct kiocb * iocb,struct iov_iter * iter)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 
fat_get_block_bmap(struct inode * inode,sector_t iblock,struct buffer_head * bh_result,int create)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 
_fat_bmap(struct address_space * mapping,sector_t block)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  */
fat_block_truncate_page(struct inode * inode,loff_t from)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 
fat_hash_init(struct super_block * sb)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 
fat_hash(loff_t i_pos)383 static inline unsigned long fat_hash(loff_t i_pos)
384 {
385 	return hash_32(i_pos, FAT_HASH_BITS);
386 }
387 
dir_hash_init(struct super_block * sb)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 
fat_attach(struct inode * inode,loff_t i_pos)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 
fat_detach(struct inode * inode)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 
fat_iget(struct super_block * sb,loff_t i_pos)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 
is_exec(unsigned char * extension)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 
fat_calc_dir_size(struct inode * inode)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 
fat_validate_dir(struct inode * dir)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 */
fat_fill_inode(struct inode * inode,struct msdos_dir_entry * de)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 		inode->i_ctime = inode->i_atime = inode->i_mtime;
568 
569 	return 0;
570 }
571 
fat_lock_build_inode(struct msdos_sb_info * sbi)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 
fat_unlock_build_inode(struct msdos_sb_info * sbi)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 
fat_build_inode(struct super_block * sb,struct msdos_dir_entry * de,loff_t i_pos)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 
fat_free_eofblocks(struct inode * inode)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 
fat_evict_inode(struct inode * inode)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 
fat_set_state(struct super_block * sb,unsigned int set,unsigned int force)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 (sbi->fat_bits == 32) {
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 
fat_reset_iocharset(struct fat_mount_options * opts)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 
delayed_free(struct rcu_head * p)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 
fat_put_super(struct super_block * sb)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 
fat_alloc_inode(struct super_block * sb)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 	/* Zeroing to allow iput() even if partial initialized inode. */
747 	ei->mmu_private = 0;
748 	ei->i_start = 0;
749 	ei->i_logstart = 0;
750 	ei->i_attrs = 0;
751 	ei->i_pos = 0;
752 
753 	return &ei->vfs_inode;
754 }
755 
fat_i_callback(struct rcu_head * head)756 static void fat_i_callback(struct rcu_head *head)
757 {
758 	struct inode *inode = container_of(head, struct inode, i_rcu);
759 	kmem_cache_free(fat_inode_cachep, MSDOS_I(inode));
760 }
761 
fat_destroy_inode(struct inode * inode)762 static void fat_destroy_inode(struct inode *inode)
763 {
764 	call_rcu(&inode->i_rcu, fat_i_callback);
765 }
766 
init_once(void * foo)767 static void init_once(void *foo)
768 {
769 	struct msdos_inode_info *ei = (struct msdos_inode_info *)foo;
770 
771 	spin_lock_init(&ei->cache_lru_lock);
772 	ei->nr_caches = 0;
773 	ei->cache_valid_id = FAT_CACHE_VALID + 1;
774 	INIT_LIST_HEAD(&ei->cache_lru);
775 	INIT_HLIST_NODE(&ei->i_fat_hash);
776 	INIT_HLIST_NODE(&ei->i_dir_hash);
777 	inode_init_once(&ei->vfs_inode);
778 }
779 
fat_init_inodecache(void)780 static int __init fat_init_inodecache(void)
781 {
782 	fat_inode_cachep = kmem_cache_create("fat_inode_cache",
783 					     sizeof(struct msdos_inode_info),
784 					     0, (SLAB_RECLAIM_ACCOUNT|
785 						SLAB_MEM_SPREAD|SLAB_ACCOUNT),
786 					     init_once);
787 	if (fat_inode_cachep == NULL)
788 		return -ENOMEM;
789 	return 0;
790 }
791 
fat_destroy_inodecache(void)792 static void __exit fat_destroy_inodecache(void)
793 {
794 	/*
795 	 * Make sure all delayed rcu free inodes are flushed before we
796 	 * destroy cache.
797 	 */
798 	rcu_barrier();
799 	kmem_cache_destroy(fat_inode_cachep);
800 }
801 
fat_remount(struct super_block * sb,int * flags,char * data)802 static int fat_remount(struct super_block *sb, int *flags, char *data)
803 {
804 	bool new_rdonly;
805 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
806 	*flags |= SB_NODIRATIME | (sbi->options.isvfat ? 0 : SB_NOATIME);
807 
808 	sync_filesystem(sb);
809 
810 	/* make sure we update state on remount. */
811 	new_rdonly = *flags & SB_RDONLY;
812 	if (new_rdonly != sb_rdonly(sb)) {
813 		if (new_rdonly)
814 			fat_set_state(sb, 0, 0);
815 		else
816 			fat_set_state(sb, 1, 1);
817 	}
818 	return 0;
819 }
820 
fat_statfs(struct dentry * dentry,struct kstatfs * buf)821 static int fat_statfs(struct dentry *dentry, struct kstatfs *buf)
822 {
823 	struct super_block *sb = dentry->d_sb;
824 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
825 	u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
826 
827 	/* If the count of free cluster is still unknown, counts it here. */
828 	if (sbi->free_clusters == -1 || !sbi->free_clus_valid) {
829 		int err = fat_count_free_clusters(dentry->d_sb);
830 		if (err)
831 			return err;
832 	}
833 
834 	buf->f_type = dentry->d_sb->s_magic;
835 	buf->f_bsize = sbi->cluster_size;
836 	buf->f_blocks = sbi->max_cluster - FAT_START_ENT;
837 	buf->f_bfree = sbi->free_clusters;
838 	buf->f_bavail = sbi->free_clusters;
839 	buf->f_fsid.val[0] = (u32)id;
840 	buf->f_fsid.val[1] = (u32)(id >> 32);
841 	buf->f_namelen =
842 		(sbi->options.isvfat ? FAT_LFN_LEN : 12) * NLS_MAX_CHARSET_SIZE;
843 
844 	return 0;
845 }
846 
__fat_write_inode(struct inode * inode,int wait)847 static int __fat_write_inode(struct inode *inode, int wait)
848 {
849 	struct super_block *sb = inode->i_sb;
850 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
851 	struct buffer_head *bh;
852 	struct msdos_dir_entry *raw_entry;
853 	loff_t i_pos;
854 	sector_t blocknr;
855 	int err, offset;
856 
857 	if (inode->i_ino == MSDOS_ROOT_INO)
858 		return 0;
859 
860 retry:
861 	i_pos = fat_i_pos_read(sbi, inode);
862 	if (!i_pos)
863 		return 0;
864 
865 	fat_get_blknr_offset(sbi, i_pos, &blocknr, &offset);
866 	bh = sb_bread(sb, blocknr);
867 	if (!bh) {
868 		fat_msg(sb, KERN_ERR, "unable to read inode block "
869 		       "for updating (i_pos %lld)", i_pos);
870 		return -EIO;
871 	}
872 	spin_lock(&sbi->inode_hash_lock);
873 	if (i_pos != MSDOS_I(inode)->i_pos) {
874 		spin_unlock(&sbi->inode_hash_lock);
875 		brelse(bh);
876 		goto retry;
877 	}
878 
879 	raw_entry = &((struct msdos_dir_entry *) (bh->b_data))[offset];
880 	if (S_ISDIR(inode->i_mode))
881 		raw_entry->size = 0;
882 	else
883 		raw_entry->size = cpu_to_le32(inode->i_size);
884 	raw_entry->attr = fat_make_attrs(inode);
885 	fat_set_start(raw_entry, MSDOS_I(inode)->i_logstart);
886 	fat_time_unix2fat(sbi, &inode->i_mtime, &raw_entry->time,
887 			  &raw_entry->date, NULL);
888 	if (sbi->options.isvfat) {
889 		__le16 atime;
890 		fat_time_unix2fat(sbi, &inode->i_ctime, &raw_entry->ctime,
891 				  &raw_entry->cdate, &raw_entry->ctime_cs);
892 		fat_time_unix2fat(sbi, &inode->i_atime, &atime,
893 				  &raw_entry->adate, NULL);
894 	}
895 	spin_unlock(&sbi->inode_hash_lock);
896 	mark_buffer_dirty(bh);
897 	err = 0;
898 	if (wait)
899 		err = sync_dirty_buffer(bh);
900 	brelse(bh);
901 	return err;
902 }
903 
fat_write_inode(struct inode * inode,struct writeback_control * wbc)904 static int fat_write_inode(struct inode *inode, struct writeback_control *wbc)
905 {
906 	int err;
907 
908 	if (inode->i_ino == MSDOS_FSINFO_INO) {
909 		struct super_block *sb = inode->i_sb;
910 
911 		mutex_lock(&MSDOS_SB(sb)->s_lock);
912 		err = fat_clusters_flush(sb);
913 		mutex_unlock(&MSDOS_SB(sb)->s_lock);
914 	} else
915 		err = __fat_write_inode(inode, wbc->sync_mode == WB_SYNC_ALL);
916 
917 	return err;
918 }
919 
fat_sync_inode(struct inode * inode)920 int fat_sync_inode(struct inode *inode)
921 {
922 	return __fat_write_inode(inode, 1);
923 }
924 
925 EXPORT_SYMBOL_GPL(fat_sync_inode);
926 
927 static int fat_show_options(struct seq_file *m, struct dentry *root);
928 static const struct super_operations fat_sops = {
929 	.alloc_inode	= fat_alloc_inode,
930 	.destroy_inode	= fat_destroy_inode,
931 	.write_inode	= fat_write_inode,
932 	.evict_inode	= fat_evict_inode,
933 	.put_super	= fat_put_super,
934 	.statfs		= fat_statfs,
935 	.remount_fs	= fat_remount,
936 
937 	.show_options	= fat_show_options,
938 };
939 
fat_show_options(struct seq_file * m,struct dentry * root)940 static int fat_show_options(struct seq_file *m, struct dentry *root)
941 {
942 	struct msdos_sb_info *sbi = MSDOS_SB(root->d_sb);
943 	struct fat_mount_options *opts = &sbi->options;
944 	int isvfat = opts->isvfat;
945 
946 	if (!uid_eq(opts->fs_uid, GLOBAL_ROOT_UID))
947 		seq_printf(m, ",uid=%u",
948 				from_kuid_munged(&init_user_ns, opts->fs_uid));
949 	if (!gid_eq(opts->fs_gid, GLOBAL_ROOT_GID))
950 		seq_printf(m, ",gid=%u",
951 				from_kgid_munged(&init_user_ns, opts->fs_gid));
952 	seq_printf(m, ",fmask=%04o", opts->fs_fmask);
953 	seq_printf(m, ",dmask=%04o", opts->fs_dmask);
954 	if (opts->allow_utime)
955 		seq_printf(m, ",allow_utime=%04o", opts->allow_utime);
956 	if (sbi->nls_disk)
957 		/* strip "cp" prefix from displayed option */
958 		seq_printf(m, ",codepage=%s", &sbi->nls_disk->charset[2]);
959 	if (isvfat) {
960 		if (sbi->nls_io)
961 			seq_printf(m, ",iocharset=%s", sbi->nls_io->charset);
962 
963 		switch (opts->shortname) {
964 		case VFAT_SFN_DISPLAY_WIN95 | VFAT_SFN_CREATE_WIN95:
965 			seq_puts(m, ",shortname=win95");
966 			break;
967 		case VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WINNT:
968 			seq_puts(m, ",shortname=winnt");
969 			break;
970 		case VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WIN95:
971 			seq_puts(m, ",shortname=mixed");
972 			break;
973 		case VFAT_SFN_DISPLAY_LOWER | VFAT_SFN_CREATE_WIN95:
974 			seq_puts(m, ",shortname=lower");
975 			break;
976 		default:
977 			seq_puts(m, ",shortname=unknown");
978 			break;
979 		}
980 	}
981 	if (opts->name_check != 'n')
982 		seq_printf(m, ",check=%c", opts->name_check);
983 	if (opts->usefree)
984 		seq_puts(m, ",usefree");
985 	if (opts->quiet)
986 		seq_puts(m, ",quiet");
987 	if (opts->showexec)
988 		seq_puts(m, ",showexec");
989 	if (opts->sys_immutable)
990 		seq_puts(m, ",sys_immutable");
991 	if (!isvfat) {
992 		if (opts->dotsOK)
993 			seq_puts(m, ",dotsOK=yes");
994 		if (opts->nocase)
995 			seq_puts(m, ",nocase");
996 	} else {
997 		if (opts->utf8)
998 			seq_puts(m, ",utf8");
999 		if (opts->unicode_xlate)
1000 			seq_puts(m, ",uni_xlate");
1001 		if (!opts->numtail)
1002 			seq_puts(m, ",nonumtail");
1003 		if (opts->rodir)
1004 			seq_puts(m, ",rodir");
1005 	}
1006 	if (opts->flush)
1007 		seq_puts(m, ",flush");
1008 	if (opts->tz_set) {
1009 		if (opts->time_offset)
1010 			seq_printf(m, ",time_offset=%d", opts->time_offset);
1011 		else
1012 			seq_puts(m, ",tz=UTC");
1013 	}
1014 	if (opts->errors == FAT_ERRORS_CONT)
1015 		seq_puts(m, ",errors=continue");
1016 	else if (opts->errors == FAT_ERRORS_PANIC)
1017 		seq_puts(m, ",errors=panic");
1018 	else
1019 		seq_puts(m, ",errors=remount-ro");
1020 	if (opts->nfs == FAT_NFS_NOSTALE_RO)
1021 		seq_puts(m, ",nfs=nostale_ro");
1022 	else if (opts->nfs)
1023 		seq_puts(m, ",nfs=stale_rw");
1024 	if (opts->discard)
1025 		seq_puts(m, ",discard");
1026 	if (opts->dos1xfloppy)
1027 		seq_puts(m, ",dos1xfloppy");
1028 
1029 	return 0;
1030 }
1031 
1032 enum {
1033 	Opt_check_n, Opt_check_r, Opt_check_s, Opt_uid, Opt_gid,
1034 	Opt_umask, Opt_dmask, Opt_fmask, Opt_allow_utime, Opt_codepage,
1035 	Opt_usefree, Opt_nocase, Opt_quiet, Opt_showexec, Opt_debug,
1036 	Opt_immutable, Opt_dots, Opt_nodots,
1037 	Opt_charset, Opt_shortname_lower, Opt_shortname_win95,
1038 	Opt_shortname_winnt, Opt_shortname_mixed, Opt_utf8_no, Opt_utf8_yes,
1039 	Opt_uni_xl_no, Opt_uni_xl_yes, Opt_nonumtail_no, Opt_nonumtail_yes,
1040 	Opt_obsolete, Opt_flush, Opt_tz_utc, Opt_rodir, Opt_err_cont,
1041 	Opt_err_panic, Opt_err_ro, Opt_discard, Opt_nfs, Opt_time_offset,
1042 	Opt_nfs_stale_rw, Opt_nfs_nostale_ro, Opt_err, Opt_dos1xfloppy,
1043 };
1044 
1045 static const match_table_t fat_tokens = {
1046 	{Opt_check_r, "check=relaxed"},
1047 	{Opt_check_s, "check=strict"},
1048 	{Opt_check_n, "check=normal"},
1049 	{Opt_check_r, "check=r"},
1050 	{Opt_check_s, "check=s"},
1051 	{Opt_check_n, "check=n"},
1052 	{Opt_uid, "uid=%u"},
1053 	{Opt_gid, "gid=%u"},
1054 	{Opt_umask, "umask=%o"},
1055 	{Opt_dmask, "dmask=%o"},
1056 	{Opt_fmask, "fmask=%o"},
1057 	{Opt_allow_utime, "allow_utime=%o"},
1058 	{Opt_codepage, "codepage=%u"},
1059 	{Opt_usefree, "usefree"},
1060 	{Opt_nocase, "nocase"},
1061 	{Opt_quiet, "quiet"},
1062 	{Opt_showexec, "showexec"},
1063 	{Opt_debug, "debug"},
1064 	{Opt_immutable, "sys_immutable"},
1065 	{Opt_flush, "flush"},
1066 	{Opt_tz_utc, "tz=UTC"},
1067 	{Opt_time_offset, "time_offset=%d"},
1068 	{Opt_err_cont, "errors=continue"},
1069 	{Opt_err_panic, "errors=panic"},
1070 	{Opt_err_ro, "errors=remount-ro"},
1071 	{Opt_discard, "discard"},
1072 	{Opt_nfs_stale_rw, "nfs"},
1073 	{Opt_nfs_stale_rw, "nfs=stale_rw"},
1074 	{Opt_nfs_nostale_ro, "nfs=nostale_ro"},
1075 	{Opt_dos1xfloppy, "dos1xfloppy"},
1076 	{Opt_obsolete, "conv=binary"},
1077 	{Opt_obsolete, "conv=text"},
1078 	{Opt_obsolete, "conv=auto"},
1079 	{Opt_obsolete, "conv=b"},
1080 	{Opt_obsolete, "conv=t"},
1081 	{Opt_obsolete, "conv=a"},
1082 	{Opt_obsolete, "fat=%u"},
1083 	{Opt_obsolete, "blocksize=%u"},
1084 	{Opt_obsolete, "cvf_format=%20s"},
1085 	{Opt_obsolete, "cvf_options=%100s"},
1086 	{Opt_obsolete, "posix"},
1087 	{Opt_err, NULL},
1088 };
1089 static const match_table_t msdos_tokens = {
1090 	{Opt_nodots, "nodots"},
1091 	{Opt_nodots, "dotsOK=no"},
1092 	{Opt_dots, "dots"},
1093 	{Opt_dots, "dotsOK=yes"},
1094 	{Opt_err, NULL}
1095 };
1096 static const match_table_t vfat_tokens = {
1097 	{Opt_charset, "iocharset=%s"},
1098 	{Opt_shortname_lower, "shortname=lower"},
1099 	{Opt_shortname_win95, "shortname=win95"},
1100 	{Opt_shortname_winnt, "shortname=winnt"},
1101 	{Opt_shortname_mixed, "shortname=mixed"},
1102 	{Opt_utf8_no, "utf8=0"},		/* 0 or no or false */
1103 	{Opt_utf8_no, "utf8=no"},
1104 	{Opt_utf8_no, "utf8=false"},
1105 	{Opt_utf8_yes, "utf8=1"},		/* empty or 1 or yes or true */
1106 	{Opt_utf8_yes, "utf8=yes"},
1107 	{Opt_utf8_yes, "utf8=true"},
1108 	{Opt_utf8_yes, "utf8"},
1109 	{Opt_uni_xl_no, "uni_xlate=0"},		/* 0 or no or false */
1110 	{Opt_uni_xl_no, "uni_xlate=no"},
1111 	{Opt_uni_xl_no, "uni_xlate=false"},
1112 	{Opt_uni_xl_yes, "uni_xlate=1"},	/* empty or 1 or yes or true */
1113 	{Opt_uni_xl_yes, "uni_xlate=yes"},
1114 	{Opt_uni_xl_yes, "uni_xlate=true"},
1115 	{Opt_uni_xl_yes, "uni_xlate"},
1116 	{Opt_nonumtail_no, "nonumtail=0"},	/* 0 or no or false */
1117 	{Opt_nonumtail_no, "nonumtail=no"},
1118 	{Opt_nonumtail_no, "nonumtail=false"},
1119 	{Opt_nonumtail_yes, "nonumtail=1"},	/* empty or 1 or yes or true */
1120 	{Opt_nonumtail_yes, "nonumtail=yes"},
1121 	{Opt_nonumtail_yes, "nonumtail=true"},
1122 	{Opt_nonumtail_yes, "nonumtail"},
1123 	{Opt_rodir, "rodir"},
1124 	{Opt_err, NULL}
1125 };
1126 
parse_options(struct super_block * sb,char * options,int is_vfat,int silent,int * debug,struct fat_mount_options * opts)1127 static int parse_options(struct super_block *sb, char *options, int is_vfat,
1128 			 int silent, int *debug, struct fat_mount_options *opts)
1129 {
1130 	char *p;
1131 	substring_t args[MAX_OPT_ARGS];
1132 	int option;
1133 	char *iocharset;
1134 
1135 	opts->isvfat = is_vfat;
1136 
1137 	opts->fs_uid = current_uid();
1138 	opts->fs_gid = current_gid();
1139 	opts->fs_fmask = opts->fs_dmask = current_umask();
1140 	opts->allow_utime = -1;
1141 	opts->codepage = fat_default_codepage;
1142 	fat_reset_iocharset(opts);
1143 	if (is_vfat) {
1144 		opts->shortname = VFAT_SFN_DISPLAY_WINNT|VFAT_SFN_CREATE_WIN95;
1145 		opts->rodir = 0;
1146 	} else {
1147 		opts->shortname = 0;
1148 		opts->rodir = 1;
1149 	}
1150 	opts->name_check = 'n';
1151 	opts->quiet = opts->showexec = opts->sys_immutable = opts->dotsOK =  0;
1152 	opts->unicode_xlate = 0;
1153 	opts->numtail = 1;
1154 	opts->usefree = opts->nocase = 0;
1155 	opts->tz_set = 0;
1156 	opts->nfs = 0;
1157 	opts->errors = FAT_ERRORS_RO;
1158 	*debug = 0;
1159 
1160 	opts->utf8 = IS_ENABLED(CONFIG_FAT_DEFAULT_UTF8) && is_vfat;
1161 
1162 	if (!options)
1163 		goto out;
1164 
1165 	while ((p = strsep(&options, ",")) != NULL) {
1166 		int token;
1167 		if (!*p)
1168 			continue;
1169 
1170 		token = match_token(p, fat_tokens, args);
1171 		if (token == Opt_err) {
1172 			if (is_vfat)
1173 				token = match_token(p, vfat_tokens, args);
1174 			else
1175 				token = match_token(p, msdos_tokens, args);
1176 		}
1177 		switch (token) {
1178 		case Opt_check_s:
1179 			opts->name_check = 's';
1180 			break;
1181 		case Opt_check_r:
1182 			opts->name_check = 'r';
1183 			break;
1184 		case Opt_check_n:
1185 			opts->name_check = 'n';
1186 			break;
1187 		case Opt_usefree:
1188 			opts->usefree = 1;
1189 			break;
1190 		case Opt_nocase:
1191 			if (!is_vfat)
1192 				opts->nocase = 1;
1193 			else {
1194 				/* for backward compatibility */
1195 				opts->shortname = VFAT_SFN_DISPLAY_WIN95
1196 					| VFAT_SFN_CREATE_WIN95;
1197 			}
1198 			break;
1199 		case Opt_quiet:
1200 			opts->quiet = 1;
1201 			break;
1202 		case Opt_showexec:
1203 			opts->showexec = 1;
1204 			break;
1205 		case Opt_debug:
1206 			*debug = 1;
1207 			break;
1208 		case Opt_immutable:
1209 			opts->sys_immutable = 1;
1210 			break;
1211 		case Opt_uid:
1212 			if (match_int(&args[0], &option))
1213 				return -EINVAL;
1214 			opts->fs_uid = make_kuid(current_user_ns(), option);
1215 			if (!uid_valid(opts->fs_uid))
1216 				return -EINVAL;
1217 			break;
1218 		case Opt_gid:
1219 			if (match_int(&args[0], &option))
1220 				return -EINVAL;
1221 			opts->fs_gid = make_kgid(current_user_ns(), option);
1222 			if (!gid_valid(opts->fs_gid))
1223 				return -EINVAL;
1224 			break;
1225 		case Opt_umask:
1226 			if (match_octal(&args[0], &option))
1227 				return -EINVAL;
1228 			opts->fs_fmask = opts->fs_dmask = option;
1229 			break;
1230 		case Opt_dmask:
1231 			if (match_octal(&args[0], &option))
1232 				return -EINVAL;
1233 			opts->fs_dmask = option;
1234 			break;
1235 		case Opt_fmask:
1236 			if (match_octal(&args[0], &option))
1237 				return -EINVAL;
1238 			opts->fs_fmask = option;
1239 			break;
1240 		case Opt_allow_utime:
1241 			if (match_octal(&args[0], &option))
1242 				return -EINVAL;
1243 			opts->allow_utime = option & (S_IWGRP | S_IWOTH);
1244 			break;
1245 		case Opt_codepage:
1246 			if (match_int(&args[0], &option))
1247 				return -EINVAL;
1248 			opts->codepage = option;
1249 			break;
1250 		case Opt_flush:
1251 			opts->flush = 1;
1252 			break;
1253 		case Opt_time_offset:
1254 			if (match_int(&args[0], &option))
1255 				return -EINVAL;
1256 			/*
1257 			 * GMT+-12 zones may have DST corrections so at least
1258 			 * 13 hours difference is needed. Make the limit 24
1259 			 * just in case someone invents something unusual.
1260 			 */
1261 			if (option < -24 * 60 || option > 24 * 60)
1262 				return -EINVAL;
1263 			opts->tz_set = 1;
1264 			opts->time_offset = option;
1265 			break;
1266 		case Opt_tz_utc:
1267 			opts->tz_set = 1;
1268 			opts->time_offset = 0;
1269 			break;
1270 		case Opt_err_cont:
1271 			opts->errors = FAT_ERRORS_CONT;
1272 			break;
1273 		case Opt_err_panic:
1274 			opts->errors = FAT_ERRORS_PANIC;
1275 			break;
1276 		case Opt_err_ro:
1277 			opts->errors = FAT_ERRORS_RO;
1278 			break;
1279 		case Opt_nfs_stale_rw:
1280 			opts->nfs = FAT_NFS_STALE_RW;
1281 			break;
1282 		case Opt_nfs_nostale_ro:
1283 			opts->nfs = FAT_NFS_NOSTALE_RO;
1284 			break;
1285 		case Opt_dos1xfloppy:
1286 			opts->dos1xfloppy = 1;
1287 			break;
1288 
1289 		/* msdos specific */
1290 		case Opt_dots:
1291 			opts->dotsOK = 1;
1292 			break;
1293 		case Opt_nodots:
1294 			opts->dotsOK = 0;
1295 			break;
1296 
1297 		/* vfat specific */
1298 		case Opt_charset:
1299 			fat_reset_iocharset(opts);
1300 			iocharset = match_strdup(&args[0]);
1301 			if (!iocharset)
1302 				return -ENOMEM;
1303 			opts->iocharset = iocharset;
1304 			break;
1305 		case Opt_shortname_lower:
1306 			opts->shortname = VFAT_SFN_DISPLAY_LOWER
1307 					| VFAT_SFN_CREATE_WIN95;
1308 			break;
1309 		case Opt_shortname_win95:
1310 			opts->shortname = VFAT_SFN_DISPLAY_WIN95
1311 					| VFAT_SFN_CREATE_WIN95;
1312 			break;
1313 		case Opt_shortname_winnt:
1314 			opts->shortname = VFAT_SFN_DISPLAY_WINNT
1315 					| VFAT_SFN_CREATE_WINNT;
1316 			break;
1317 		case Opt_shortname_mixed:
1318 			opts->shortname = VFAT_SFN_DISPLAY_WINNT
1319 					| VFAT_SFN_CREATE_WIN95;
1320 			break;
1321 		case Opt_utf8_no:		/* 0 or no or false */
1322 			opts->utf8 = 0;
1323 			break;
1324 		case Opt_utf8_yes:		/* empty or 1 or yes or true */
1325 			opts->utf8 = 1;
1326 			break;
1327 		case Opt_uni_xl_no:		/* 0 or no or false */
1328 			opts->unicode_xlate = 0;
1329 			break;
1330 		case Opt_uni_xl_yes:		/* empty or 1 or yes or true */
1331 			opts->unicode_xlate = 1;
1332 			break;
1333 		case Opt_nonumtail_no:		/* 0 or no or false */
1334 			opts->numtail = 1;	/* negated option */
1335 			break;
1336 		case Opt_nonumtail_yes:		/* empty or 1 or yes or true */
1337 			opts->numtail = 0;	/* negated option */
1338 			break;
1339 		case Opt_rodir:
1340 			opts->rodir = 1;
1341 			break;
1342 		case Opt_discard:
1343 			opts->discard = 1;
1344 			break;
1345 
1346 		/* obsolete mount options */
1347 		case Opt_obsolete:
1348 			fat_msg(sb, KERN_INFO, "\"%s\" option is obsolete, "
1349 			       "not supported now", p);
1350 			break;
1351 		/* unknown option */
1352 		default:
1353 			if (!silent) {
1354 				fat_msg(sb, KERN_ERR,
1355 				       "Unrecognized mount option \"%s\" "
1356 				       "or missing value", p);
1357 			}
1358 			return -EINVAL;
1359 		}
1360 	}
1361 
1362 out:
1363 	/* UTF-8 doesn't provide FAT semantics */
1364 	if (!strcmp(opts->iocharset, "utf8")) {
1365 		fat_msg(sb, KERN_WARNING, "utf8 is not a recommended IO charset"
1366 		       " for FAT filesystems, filesystem will be "
1367 		       "case sensitive!");
1368 	}
1369 
1370 	/* If user doesn't specify allow_utime, it's initialized from dmask. */
1371 	if (opts->allow_utime == (unsigned short)-1)
1372 		opts->allow_utime = ~opts->fs_dmask & (S_IWGRP | S_IWOTH);
1373 	if (opts->unicode_xlate)
1374 		opts->utf8 = 0;
1375 	if (opts->nfs == FAT_NFS_NOSTALE_RO) {
1376 		sb->s_flags |= SB_RDONLY;
1377 		sb->s_export_op = &fat_export_ops_nostale;
1378 	}
1379 
1380 	return 0;
1381 }
1382 
fat_read_root(struct inode * inode)1383 static int fat_read_root(struct inode *inode)
1384 {
1385 	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
1386 	int error;
1387 
1388 	MSDOS_I(inode)->i_pos = MSDOS_ROOT_INO;
1389 	inode->i_uid = sbi->options.fs_uid;
1390 	inode->i_gid = sbi->options.fs_gid;
1391 	inode_inc_iversion(inode);
1392 	inode->i_generation = 0;
1393 	inode->i_mode = fat_make_mode(sbi, ATTR_DIR, S_IRWXUGO);
1394 	inode->i_op = sbi->dir_ops;
1395 	inode->i_fop = &fat_dir_operations;
1396 	if (sbi->fat_bits == 32) {
1397 		MSDOS_I(inode)->i_start = sbi->root_cluster;
1398 		error = fat_calc_dir_size(inode);
1399 		if (error < 0)
1400 			return error;
1401 	} else {
1402 		MSDOS_I(inode)->i_start = 0;
1403 		inode->i_size = sbi->dir_entries * sizeof(struct msdos_dir_entry);
1404 	}
1405 	inode->i_blocks = ((inode->i_size + (sbi->cluster_size - 1))
1406 			   & ~((loff_t)sbi->cluster_size - 1)) >> 9;
1407 	MSDOS_I(inode)->i_logstart = 0;
1408 	MSDOS_I(inode)->mmu_private = inode->i_size;
1409 
1410 	fat_save_attrs(inode, ATTR_DIR);
1411 	inode->i_mtime.tv_sec = inode->i_atime.tv_sec = inode->i_ctime.tv_sec = 0;
1412 	inode->i_mtime.tv_nsec = inode->i_atime.tv_nsec = inode->i_ctime.tv_nsec = 0;
1413 	set_nlink(inode, fat_subdirs(inode)+2);
1414 
1415 	return 0;
1416 }
1417 
calc_fat_clusters(struct super_block * sb)1418 static unsigned long calc_fat_clusters(struct super_block *sb)
1419 {
1420 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
1421 
1422 	/* Divide first to avoid overflow */
1423 	if (sbi->fat_bits != 12) {
1424 		unsigned long ent_per_sec = sb->s_blocksize * 8 / sbi->fat_bits;
1425 		return ent_per_sec * sbi->fat_length;
1426 	}
1427 
1428 	return sbi->fat_length * sb->s_blocksize * 8 / sbi->fat_bits;
1429 }
1430 
fat_bpb_is_zero(struct fat_boot_sector * b)1431 static bool fat_bpb_is_zero(struct fat_boot_sector *b)
1432 {
1433 	if (get_unaligned_le16(&b->sector_size))
1434 		return false;
1435 	if (b->sec_per_clus)
1436 		return false;
1437 	if (b->reserved)
1438 		return false;
1439 	if (b->fats)
1440 		return false;
1441 	if (get_unaligned_le16(&b->dir_entries))
1442 		return false;
1443 	if (get_unaligned_le16(&b->sectors))
1444 		return false;
1445 	if (b->media)
1446 		return false;
1447 	if (b->fat_length)
1448 		return false;
1449 	if (b->secs_track)
1450 		return false;
1451 	if (b->heads)
1452 		return false;
1453 	return true;
1454 }
1455 
fat_read_bpb(struct super_block * sb,struct fat_boot_sector * b,int silent,struct fat_bios_param_block * bpb)1456 static int fat_read_bpb(struct super_block *sb, struct fat_boot_sector *b,
1457 	int silent, struct fat_bios_param_block *bpb)
1458 {
1459 	int error = -EINVAL;
1460 
1461 	/* Read in BPB ... */
1462 	memset(bpb, 0, sizeof(*bpb));
1463 	bpb->fat_sector_size = get_unaligned_le16(&b->sector_size);
1464 	bpb->fat_sec_per_clus = b->sec_per_clus;
1465 	bpb->fat_reserved = le16_to_cpu(b->reserved);
1466 	bpb->fat_fats = b->fats;
1467 	bpb->fat_dir_entries = get_unaligned_le16(&b->dir_entries);
1468 	bpb->fat_sectors = get_unaligned_le16(&b->sectors);
1469 	bpb->fat_fat_length = le16_to_cpu(b->fat_length);
1470 	bpb->fat_total_sect = le32_to_cpu(b->total_sect);
1471 
1472 	bpb->fat16_state = b->fat16.state;
1473 	bpb->fat16_vol_id = get_unaligned_le32(b->fat16.vol_id);
1474 
1475 	bpb->fat32_length = le32_to_cpu(b->fat32.length);
1476 	bpb->fat32_root_cluster = le32_to_cpu(b->fat32.root_cluster);
1477 	bpb->fat32_info_sector = le16_to_cpu(b->fat32.info_sector);
1478 	bpb->fat32_state = b->fat32.state;
1479 	bpb->fat32_vol_id = get_unaligned_le32(b->fat32.vol_id);
1480 
1481 	/* Validate this looks like a FAT filesystem BPB */
1482 	if (!bpb->fat_reserved) {
1483 		if (!silent)
1484 			fat_msg(sb, KERN_ERR,
1485 				"bogus number of reserved sectors");
1486 		goto out;
1487 	}
1488 	if (!bpb->fat_fats) {
1489 		if (!silent)
1490 			fat_msg(sb, KERN_ERR, "bogus number of FAT structure");
1491 		goto out;
1492 	}
1493 
1494 	/*
1495 	 * Earlier we checked here that b->secs_track and b->head are nonzero,
1496 	 * but it turns out valid FAT filesystems can have zero there.
1497 	 */
1498 
1499 	if (!fat_valid_media(b->media)) {
1500 		if (!silent)
1501 			fat_msg(sb, KERN_ERR, "invalid media value (0x%02x)",
1502 				(unsigned)b->media);
1503 		goto out;
1504 	}
1505 
1506 	if (!is_power_of_2(bpb->fat_sector_size)
1507 	    || (bpb->fat_sector_size < 512)
1508 	    || (bpb->fat_sector_size > 4096)) {
1509 		if (!silent)
1510 			fat_msg(sb, KERN_ERR, "bogus logical sector size %u",
1511 			       (unsigned)bpb->fat_sector_size);
1512 		goto out;
1513 	}
1514 
1515 	if (!is_power_of_2(bpb->fat_sec_per_clus)) {
1516 		if (!silent)
1517 			fat_msg(sb, KERN_ERR, "bogus sectors per cluster %u",
1518 				(unsigned)bpb->fat_sec_per_clus);
1519 		goto out;
1520 	}
1521 
1522 	if (bpb->fat_fat_length == 0 && bpb->fat32_length == 0) {
1523 		if (!silent)
1524 			fat_msg(sb, KERN_ERR, "bogus number of FAT sectors");
1525 		goto out;
1526 	}
1527 
1528 	error = 0;
1529 
1530 out:
1531 	return error;
1532 }
1533 
fat_read_static_bpb(struct super_block * sb,struct fat_boot_sector * b,int silent,struct fat_bios_param_block * bpb)1534 static int fat_read_static_bpb(struct super_block *sb,
1535 	struct fat_boot_sector *b, int silent,
1536 	struct fat_bios_param_block *bpb)
1537 {
1538 	static const char *notdos1x = "This doesn't look like a DOS 1.x volume";
1539 
1540 	struct fat_floppy_defaults *fdefaults = NULL;
1541 	int error = -EINVAL;
1542 	sector_t bd_sects;
1543 	unsigned i;
1544 
1545 	bd_sects = i_size_read(sb->s_bdev->bd_inode) / SECTOR_SIZE;
1546 
1547 	/* 16-bit DOS 1.x reliably wrote bootstrap short-jmp code */
1548 	if (b->ignored[0] != 0xeb || b->ignored[2] != 0x90) {
1549 		if (!silent)
1550 			fat_msg(sb, KERN_ERR,
1551 				"%s; no bootstrapping code", notdos1x);
1552 		goto out;
1553 	}
1554 
1555 	/*
1556 	 * If any value in this region is non-zero, it isn't archaic
1557 	 * DOS.
1558 	 */
1559 	if (!fat_bpb_is_zero(b)) {
1560 		if (!silent)
1561 			fat_msg(sb, KERN_ERR,
1562 				"%s; DOS 2.x BPB is non-zero", notdos1x);
1563 		goto out;
1564 	}
1565 
1566 	for (i = 0; i < ARRAY_SIZE(floppy_defaults); i++) {
1567 		if (floppy_defaults[i].nr_sectors == bd_sects) {
1568 			fdefaults = &floppy_defaults[i];
1569 			break;
1570 		}
1571 	}
1572 
1573 	if (fdefaults == NULL) {
1574 		if (!silent)
1575 			fat_msg(sb, KERN_WARNING,
1576 				"This looks like a DOS 1.x volume, but isn't a recognized floppy size (%llu sectors)",
1577 				(u64)bd_sects);
1578 		goto out;
1579 	}
1580 
1581 	if (!silent)
1582 		fat_msg(sb, KERN_INFO,
1583 			"This looks like a DOS 1.x volume; assuming default BPB values");
1584 
1585 	memset(bpb, 0, sizeof(*bpb));
1586 	bpb->fat_sector_size = SECTOR_SIZE;
1587 	bpb->fat_sec_per_clus = fdefaults->sec_per_clus;
1588 	bpb->fat_reserved = 1;
1589 	bpb->fat_fats = 2;
1590 	bpb->fat_dir_entries = fdefaults->dir_entries;
1591 	bpb->fat_sectors = fdefaults->nr_sectors;
1592 	bpb->fat_fat_length = fdefaults->fat_length;
1593 
1594 	error = 0;
1595 
1596 out:
1597 	return error;
1598 }
1599 
1600 /*
1601  * Read the super block of an MS-DOS FS.
1602  */
fat_fill_super(struct super_block * sb,void * data,int silent,int isvfat,void (* setup)(struct super_block *))1603 int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat,
1604 		   void (*setup)(struct super_block *))
1605 {
1606 	struct inode *root_inode = NULL, *fat_inode = NULL;
1607 	struct inode *fsinfo_inode = NULL;
1608 	struct buffer_head *bh;
1609 	struct fat_bios_param_block bpb;
1610 	struct msdos_sb_info *sbi;
1611 	u16 logical_sector_size;
1612 	u32 total_sectors, total_clusters, fat_clusters, rootdir_sectors;
1613 	int debug;
1614 	long error;
1615 	char buf[50];
1616 
1617 	/*
1618 	 * GFP_KERNEL is ok here, because while we do hold the
1619 	 * superblock lock, memory pressure can't call back into
1620 	 * the filesystem, since we're only just about to mount
1621 	 * it and have no inodes etc active!
1622 	 */
1623 	sbi = kzalloc(sizeof(struct msdos_sb_info), GFP_KERNEL);
1624 	if (!sbi)
1625 		return -ENOMEM;
1626 	sb->s_fs_info = sbi;
1627 
1628 	sb->s_flags |= SB_NODIRATIME;
1629 	sb->s_magic = MSDOS_SUPER_MAGIC;
1630 	sb->s_op = &fat_sops;
1631 	sb->s_export_op = &fat_export_ops;
1632 	mutex_init(&sbi->nfs_build_inode_lock);
1633 	ratelimit_state_init(&sbi->ratelimit, DEFAULT_RATELIMIT_INTERVAL,
1634 			     DEFAULT_RATELIMIT_BURST);
1635 
1636 	error = parse_options(sb, data, isvfat, silent, &debug, &sbi->options);
1637 	if (error)
1638 		goto out_fail;
1639 
1640 	setup(sb); /* flavour-specific stuff that needs options */
1641 
1642 	error = -EIO;
1643 	sb_min_blocksize(sb, 512);
1644 	bh = sb_bread(sb, 0);
1645 	if (bh == NULL) {
1646 		fat_msg(sb, KERN_ERR, "unable to read boot sector");
1647 		goto out_fail;
1648 	}
1649 
1650 	error = fat_read_bpb(sb, (struct fat_boot_sector *)bh->b_data, silent,
1651 		&bpb);
1652 	if (error == -EINVAL && sbi->options.dos1xfloppy)
1653 		error = fat_read_static_bpb(sb,
1654 			(struct fat_boot_sector *)bh->b_data, silent, &bpb);
1655 	brelse(bh);
1656 
1657 	if (error == -EINVAL)
1658 		goto out_invalid;
1659 	else if (error)
1660 		goto out_fail;
1661 
1662 	logical_sector_size = bpb.fat_sector_size;
1663 	sbi->sec_per_clus = bpb.fat_sec_per_clus;
1664 
1665 	error = -EIO;
1666 	if (logical_sector_size < sb->s_blocksize) {
1667 		fat_msg(sb, KERN_ERR, "logical sector size too small for device"
1668 		       " (logical sector size = %u)", logical_sector_size);
1669 		goto out_fail;
1670 	}
1671 
1672 	if (logical_sector_size > sb->s_blocksize) {
1673 		struct buffer_head *bh_resize;
1674 
1675 		if (!sb_set_blocksize(sb, logical_sector_size)) {
1676 			fat_msg(sb, KERN_ERR, "unable to set blocksize %u",
1677 			       logical_sector_size);
1678 			goto out_fail;
1679 		}
1680 
1681 		/* Verify that the larger boot sector is fully readable */
1682 		bh_resize = sb_bread(sb, 0);
1683 		if (bh_resize == NULL) {
1684 			fat_msg(sb, KERN_ERR, "unable to read boot sector"
1685 			       " (logical sector size = %lu)",
1686 			       sb->s_blocksize);
1687 			goto out_fail;
1688 		}
1689 		brelse(bh_resize);
1690 	}
1691 
1692 	mutex_init(&sbi->s_lock);
1693 	sbi->cluster_size = sb->s_blocksize * sbi->sec_per_clus;
1694 	sbi->cluster_bits = ffs(sbi->cluster_size) - 1;
1695 	sbi->fats = bpb.fat_fats;
1696 	sbi->fat_bits = 0;		/* Don't know yet */
1697 	sbi->fat_start = bpb.fat_reserved;
1698 	sbi->fat_length = bpb.fat_fat_length;
1699 	sbi->root_cluster = 0;
1700 	sbi->free_clusters = -1;	/* Don't know yet */
1701 	sbi->free_clus_valid = 0;
1702 	sbi->prev_free = FAT_START_ENT;
1703 	sb->s_maxbytes = 0xffffffff;
1704 
1705 	if (!sbi->fat_length && bpb.fat32_length) {
1706 		struct fat_boot_fsinfo *fsinfo;
1707 		struct buffer_head *fsinfo_bh;
1708 
1709 		/* Must be FAT32 */
1710 		sbi->fat_bits = 32;
1711 		sbi->fat_length = bpb.fat32_length;
1712 		sbi->root_cluster = bpb.fat32_root_cluster;
1713 
1714 		/* MC - if info_sector is 0, don't multiply by 0 */
1715 		sbi->fsinfo_sector = bpb.fat32_info_sector;
1716 		if (sbi->fsinfo_sector == 0)
1717 			sbi->fsinfo_sector = 1;
1718 
1719 		fsinfo_bh = sb_bread(sb, sbi->fsinfo_sector);
1720 		if (fsinfo_bh == NULL) {
1721 			fat_msg(sb, KERN_ERR, "bread failed, FSINFO block"
1722 			       " (sector = %lu)", sbi->fsinfo_sector);
1723 			goto out_fail;
1724 		}
1725 
1726 		fsinfo = (struct fat_boot_fsinfo *)fsinfo_bh->b_data;
1727 		if (!IS_FSINFO(fsinfo)) {
1728 			fat_msg(sb, KERN_WARNING, "Invalid FSINFO signature: "
1729 			       "0x%08x, 0x%08x (sector = %lu)",
1730 			       le32_to_cpu(fsinfo->signature1),
1731 			       le32_to_cpu(fsinfo->signature2),
1732 			       sbi->fsinfo_sector);
1733 		} else {
1734 			if (sbi->options.usefree)
1735 				sbi->free_clus_valid = 1;
1736 			sbi->free_clusters = le32_to_cpu(fsinfo->free_clusters);
1737 			sbi->prev_free = le32_to_cpu(fsinfo->next_cluster);
1738 		}
1739 
1740 		brelse(fsinfo_bh);
1741 	}
1742 
1743 	/* interpret volume ID as a little endian 32 bit integer */
1744 	if (sbi->fat_bits == 32)
1745 		sbi->vol_id = bpb.fat32_vol_id;
1746 	else /* fat 16 or 12 */
1747 		sbi->vol_id = bpb.fat16_vol_id;
1748 
1749 	sbi->dir_per_block = sb->s_blocksize / sizeof(struct msdos_dir_entry);
1750 	sbi->dir_per_block_bits = ffs(sbi->dir_per_block) - 1;
1751 
1752 	sbi->dir_start = sbi->fat_start + sbi->fats * sbi->fat_length;
1753 	sbi->dir_entries = bpb.fat_dir_entries;
1754 	if (sbi->dir_entries & (sbi->dir_per_block - 1)) {
1755 		if (!silent)
1756 			fat_msg(sb, KERN_ERR, "bogus number of directory entries"
1757 			       " (%u)", sbi->dir_entries);
1758 		goto out_invalid;
1759 	}
1760 
1761 	rootdir_sectors = sbi->dir_entries
1762 		* sizeof(struct msdos_dir_entry) / sb->s_blocksize;
1763 	sbi->data_start = sbi->dir_start + rootdir_sectors;
1764 	total_sectors = bpb.fat_sectors;
1765 	if (total_sectors == 0)
1766 		total_sectors = bpb.fat_total_sect;
1767 
1768 	total_clusters = (total_sectors - sbi->data_start) / sbi->sec_per_clus;
1769 
1770 	if (sbi->fat_bits != 32)
1771 		sbi->fat_bits = (total_clusters > MAX_FAT12) ? 16 : 12;
1772 
1773 	/* some OSes set FAT_STATE_DIRTY and clean it on unmount. */
1774 	if (sbi->fat_bits == 32)
1775 		sbi->dirty = bpb.fat32_state & FAT_STATE_DIRTY;
1776 	else /* fat 16 or 12 */
1777 		sbi->dirty = bpb.fat16_state & FAT_STATE_DIRTY;
1778 
1779 	/* check that FAT table does not overflow */
1780 	fat_clusters = calc_fat_clusters(sb);
1781 	total_clusters = min(total_clusters, fat_clusters - FAT_START_ENT);
1782 	if (total_clusters > MAX_FAT(sb)) {
1783 		if (!silent)
1784 			fat_msg(sb, KERN_ERR, "count of clusters too big (%u)",
1785 			       total_clusters);
1786 		goto out_invalid;
1787 	}
1788 
1789 	sbi->max_cluster = total_clusters + FAT_START_ENT;
1790 	/* check the free_clusters, it's not necessarily correct */
1791 	if (sbi->free_clusters != -1 && sbi->free_clusters > total_clusters)
1792 		sbi->free_clusters = -1;
1793 	/* check the prev_free, it's not necessarily correct */
1794 	sbi->prev_free %= sbi->max_cluster;
1795 	if (sbi->prev_free < FAT_START_ENT)
1796 		sbi->prev_free = FAT_START_ENT;
1797 
1798 	/* set up enough so that it can read an inode */
1799 	fat_hash_init(sb);
1800 	dir_hash_init(sb);
1801 	fat_ent_access_init(sb);
1802 
1803 	/*
1804 	 * The low byte of FAT's first entry must have same value with
1805 	 * media-field.  But in real world, too many devices is
1806 	 * writing wrong value.  So, removed that validity check.
1807 	 *
1808 	 * if (FAT_FIRST_ENT(sb, media) != first)
1809 	 */
1810 
1811 	error = -EINVAL;
1812 	sprintf(buf, "cp%d", sbi->options.codepage);
1813 	sbi->nls_disk = load_nls(buf);
1814 	if (!sbi->nls_disk) {
1815 		fat_msg(sb, KERN_ERR, "codepage %s not found", buf);
1816 		goto out_fail;
1817 	}
1818 
1819 	/* FIXME: utf8 is using iocharset for upper/lower conversion */
1820 	if (sbi->options.isvfat) {
1821 		sbi->nls_io = load_nls(sbi->options.iocharset);
1822 		if (!sbi->nls_io) {
1823 			fat_msg(sb, KERN_ERR, "IO charset %s not found",
1824 			       sbi->options.iocharset);
1825 			goto out_fail;
1826 		}
1827 	}
1828 
1829 	error = -ENOMEM;
1830 	fat_inode = new_inode(sb);
1831 	if (!fat_inode)
1832 		goto out_fail;
1833 	sbi->fat_inode = fat_inode;
1834 
1835 	fsinfo_inode = new_inode(sb);
1836 	if (!fsinfo_inode)
1837 		goto out_fail;
1838 	fsinfo_inode->i_ino = MSDOS_FSINFO_INO;
1839 	sbi->fsinfo_inode = fsinfo_inode;
1840 	insert_inode_hash(fsinfo_inode);
1841 
1842 	root_inode = new_inode(sb);
1843 	if (!root_inode)
1844 		goto out_fail;
1845 	root_inode->i_ino = MSDOS_ROOT_INO;
1846 	inode_set_iversion(root_inode, 1);
1847 	error = fat_read_root(root_inode);
1848 	if (error < 0) {
1849 		iput(root_inode);
1850 		goto out_fail;
1851 	}
1852 	error = -ENOMEM;
1853 	insert_inode_hash(root_inode);
1854 	fat_attach(root_inode, 0);
1855 	sb->s_root = d_make_root(root_inode);
1856 	if (!sb->s_root) {
1857 		fat_msg(sb, KERN_ERR, "get root inode failed");
1858 		goto out_fail;
1859 	}
1860 
1861 	if (sbi->options.discard) {
1862 		struct request_queue *q = bdev_get_queue(sb->s_bdev);
1863 		if (!blk_queue_discard(q))
1864 			fat_msg(sb, KERN_WARNING,
1865 					"mounting with \"discard\" option, but "
1866 					"the device does not support discard");
1867 	}
1868 
1869 	fat_set_state(sb, 1, 0);
1870 	return 0;
1871 
1872 out_invalid:
1873 	error = -EINVAL;
1874 	if (!silent)
1875 		fat_msg(sb, KERN_INFO, "Can't find a valid FAT filesystem");
1876 
1877 out_fail:
1878 	if (fsinfo_inode)
1879 		iput(fsinfo_inode);
1880 	if (fat_inode)
1881 		iput(fat_inode);
1882 	unload_nls(sbi->nls_io);
1883 	unload_nls(sbi->nls_disk);
1884 	fat_reset_iocharset(&sbi->options);
1885 	sb->s_fs_info = NULL;
1886 	kfree(sbi);
1887 	return error;
1888 }
1889 
1890 EXPORT_SYMBOL_GPL(fat_fill_super);
1891 
1892 /*
1893  * helper function for fat_flush_inodes.  This writes both the inode
1894  * and the file data blocks, waiting for in flight data blocks before
1895  * the start of the call.  It does not wait for any io started
1896  * during the call
1897  */
writeback_inode(struct inode * inode)1898 static int writeback_inode(struct inode *inode)
1899 {
1900 
1901 	int ret;
1902 
1903 	/* if we used wait=1, sync_inode_metadata waits for the io for the
1904 	* inode to finish.  So wait=0 is sent down to sync_inode_metadata
1905 	* and filemap_fdatawrite is used for the data blocks
1906 	*/
1907 	ret = sync_inode_metadata(inode, 0);
1908 	if (!ret)
1909 		ret = filemap_fdatawrite(inode->i_mapping);
1910 	return ret;
1911 }
1912 
1913 /*
1914  * write data and metadata corresponding to i1 and i2.  The io is
1915  * started but we do not wait for any of it to finish.
1916  *
1917  * filemap_flush is used for the block device, so if there is a dirty
1918  * page for a block already in flight, we will not wait and start the
1919  * io over again
1920  */
fat_flush_inodes(struct super_block * sb,struct inode * i1,struct inode * i2)1921 int fat_flush_inodes(struct super_block *sb, struct inode *i1, struct inode *i2)
1922 {
1923 	int ret = 0;
1924 	if (!MSDOS_SB(sb)->options.flush)
1925 		return 0;
1926 	if (i1)
1927 		ret = writeback_inode(i1);
1928 	if (!ret && i2)
1929 		ret = writeback_inode(i2);
1930 	if (!ret) {
1931 		struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping;
1932 		ret = filemap_flush(mapping);
1933 	}
1934 	return ret;
1935 }
1936 EXPORT_SYMBOL_GPL(fat_flush_inodes);
1937 
init_fat_fs(void)1938 static int __init init_fat_fs(void)
1939 {
1940 	int err;
1941 
1942 	err = fat_cache_init();
1943 	if (err)
1944 		return err;
1945 
1946 	err = fat_init_inodecache();
1947 	if (err)
1948 		goto failed;
1949 
1950 	return 0;
1951 
1952 failed:
1953 	fat_cache_destroy();
1954 	return err;
1955 }
1956 
exit_fat_fs(void)1957 static void __exit exit_fat_fs(void)
1958 {
1959 	fat_cache_destroy();
1960 	fat_destroy_inodecache();
1961 }
1962 
1963 module_init(init_fat_fs)
1964 module_exit(exit_fat_fs)
1965 
1966 MODULE_LICENSE("GPL");
1967