xref: /openbmc/linux/fs/fat/inode.c (revision f42b3800)
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/init.h>
15 #include <linux/time.h>
16 #include <linux/slab.h>
17 #include <linux/smp_lock.h>
18 #include <linux/seq_file.h>
19 #include <linux/msdos_fs.h>
20 #include <linux/pagemap.h>
21 #include <linux/mpage.h>
22 #include <linux/buffer_head.h>
23 #include <linux/exportfs.h>
24 #include <linux/mount.h>
25 #include <linux/vfs.h>
26 #include <linux/parser.h>
27 #include <linux/uio.h>
28 #include <linux/writeback.h>
29 #include <linux/log2.h>
30 #include <asm/unaligned.h>
31 
32 #ifndef CONFIG_FAT_DEFAULT_IOCHARSET
33 /* if user don't select VFAT, this is undefined. */
34 #define CONFIG_FAT_DEFAULT_IOCHARSET	""
35 #endif
36 
37 static int fat_default_codepage = CONFIG_FAT_DEFAULT_CODEPAGE;
38 static char fat_default_iocharset[] = CONFIG_FAT_DEFAULT_IOCHARSET;
39 
40 
41 static int fat_add_cluster(struct inode *inode)
42 {
43 	int err, cluster;
44 
45 	err = fat_alloc_clusters(inode, &cluster, 1);
46 	if (err)
47 		return err;
48 	/* FIXME: this cluster should be added after data of this
49 	 * cluster is writed */
50 	err = fat_chain_add(inode, cluster, 1);
51 	if (err)
52 		fat_free_clusters(inode, cluster);
53 	return err;
54 }
55 
56 static inline int __fat_get_block(struct inode *inode, sector_t iblock,
57 				  unsigned long *max_blocks,
58 				  struct buffer_head *bh_result, int create)
59 {
60 	struct super_block *sb = inode->i_sb;
61 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
62 	unsigned long mapped_blocks;
63 	sector_t phys;
64 	int err, offset;
65 
66 	err = fat_bmap(inode, iblock, &phys, &mapped_blocks);
67 	if (err)
68 		return err;
69 	if (phys) {
70 		map_bh(bh_result, sb, phys);
71 		*max_blocks = min(mapped_blocks, *max_blocks);
72 		return 0;
73 	}
74 	if (!create)
75 		return 0;
76 
77 	if (iblock != MSDOS_I(inode)->mmu_private >> sb->s_blocksize_bits) {
78 		fat_fs_panic(sb, "corrupted file size (i_pos %lld, %lld)",
79 			MSDOS_I(inode)->i_pos, MSDOS_I(inode)->mmu_private);
80 		return -EIO;
81 	}
82 
83 	offset = (unsigned long)iblock & (sbi->sec_per_clus - 1);
84 	if (!offset) {
85 		/* TODO: multiple cluster allocation would be desirable. */
86 		err = fat_add_cluster(inode);
87 		if (err)
88 			return err;
89 	}
90 	/* available blocks on this cluster */
91 	mapped_blocks = sbi->sec_per_clus - offset;
92 
93 	*max_blocks = min(mapped_blocks, *max_blocks);
94 	MSDOS_I(inode)->mmu_private += *max_blocks << sb->s_blocksize_bits;
95 
96 	err = fat_bmap(inode, iblock, &phys, &mapped_blocks);
97 	if (err)
98 		return err;
99 
100 	BUG_ON(!phys);
101 	BUG_ON(*max_blocks != mapped_blocks);
102 	set_buffer_new(bh_result);
103 	map_bh(bh_result, sb, phys);
104 
105 	return 0;
106 }
107 
108 static int fat_get_block(struct inode *inode, sector_t iblock,
109 			 struct buffer_head *bh_result, int create)
110 {
111 	struct super_block *sb = inode->i_sb;
112 	unsigned long max_blocks = bh_result->b_size >> inode->i_blkbits;
113 	int err;
114 
115 	err = __fat_get_block(inode, iblock, &max_blocks, bh_result, create);
116 	if (err)
117 		return err;
118 	bh_result->b_size = max_blocks << sb->s_blocksize_bits;
119 	return 0;
120 }
121 
122 static int fat_writepage(struct page *page, struct writeback_control *wbc)
123 {
124 	return block_write_full_page(page, fat_get_block, wbc);
125 }
126 
127 static int fat_writepages(struct address_space *mapping,
128 			  struct writeback_control *wbc)
129 {
130 	return mpage_writepages(mapping, wbc, fat_get_block);
131 }
132 
133 static int fat_readpage(struct file *file, struct page *page)
134 {
135 	return mpage_readpage(page, fat_get_block);
136 }
137 
138 static int fat_readpages(struct file *file, struct address_space *mapping,
139 			 struct list_head *pages, unsigned nr_pages)
140 {
141 	return mpage_readpages(mapping, pages, nr_pages, fat_get_block);
142 }
143 
144 static int fat_write_begin(struct file *file, struct address_space *mapping,
145 			loff_t pos, unsigned len, unsigned flags,
146 			struct page **pagep, void **fsdata)
147 {
148 	*pagep = NULL;
149 	return cont_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
150 				fat_get_block,
151 				&MSDOS_I(mapping->host)->mmu_private);
152 }
153 
154 static int fat_write_end(struct file *file, struct address_space *mapping,
155 			loff_t pos, unsigned len, unsigned copied,
156 			struct page *pagep, void *fsdata)
157 {
158 	struct inode *inode = mapping->host;
159 	int err;
160 	err = generic_write_end(file, mapping, pos, len, copied, pagep, fsdata);
161 	if (!(err < 0) && !(MSDOS_I(inode)->i_attrs & ATTR_ARCH)) {
162 		inode->i_mtime = inode->i_ctime = CURRENT_TIME_SEC;
163 		MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
164 		mark_inode_dirty(inode);
165 	}
166 	return err;
167 }
168 
169 static ssize_t fat_direct_IO(int rw, struct kiocb *iocb,
170 			     const struct iovec *iov,
171 			     loff_t offset, unsigned long nr_segs)
172 {
173 	struct file *file = iocb->ki_filp;
174 	struct inode *inode = file->f_mapping->host;
175 
176 	if (rw == WRITE) {
177 		/*
178 		 * FIXME: blockdev_direct_IO() doesn't use ->prepare_write(),
179 		 * so we need to update the ->mmu_private to block boundary.
180 		 *
181 		 * But we must fill the remaining area or hole by nul for
182 		 * updating ->mmu_private.
183 		 *
184 		 * Return 0, and fallback to normal buffered write.
185 		 */
186 		loff_t size = offset + iov_length(iov, nr_segs);
187 		if (MSDOS_I(inode)->mmu_private < size)
188 			return 0;
189 	}
190 
191 	/*
192 	 * FAT need to use the DIO_LOCKING for avoiding the race
193 	 * condition of fat_get_block() and ->truncate().
194 	 */
195 	return blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iov,
196 				  offset, nr_segs, fat_get_block, NULL);
197 }
198 
199 static sector_t _fat_bmap(struct address_space *mapping, sector_t block)
200 {
201 	return generic_block_bmap(mapping, block, fat_get_block);
202 }
203 
204 static const struct address_space_operations fat_aops = {
205 	.readpage	= fat_readpage,
206 	.readpages	= fat_readpages,
207 	.writepage	= fat_writepage,
208 	.writepages	= fat_writepages,
209 	.sync_page	= block_sync_page,
210 	.write_begin	= fat_write_begin,
211 	.write_end	= fat_write_end,
212 	.direct_IO	= fat_direct_IO,
213 	.bmap		= _fat_bmap
214 };
215 
216 /*
217  * New FAT inode stuff. We do the following:
218  *	a) i_ino is constant and has nothing with on-disk location.
219  *	b) FAT manages its own cache of directory entries.
220  *	c) *This* cache is indexed by on-disk location.
221  *	d) inode has an associated directory entry, all right, but
222  *		it may be unhashed.
223  *	e) currently entries are stored within struct inode. That should
224  *		change.
225  *	f) we deal with races in the following way:
226  *		1. readdir() and lookup() do FAT-dir-cache lookup.
227  *		2. rename() unhashes the F-d-c entry and rehashes it in
228  *			a new place.
229  *		3. unlink() and rmdir() unhash F-d-c entry.
230  *		4. fat_write_inode() checks whether the thing is unhashed.
231  *			If it is we silently return. If it isn't we do bread(),
232  *			check if the location is still valid and retry if it
233  *			isn't. Otherwise we do changes.
234  *		5. Spinlock is used to protect hash/unhash/location check/lookup
235  *		6. fat_clear_inode() unhashes the F-d-c entry.
236  *		7. lookup() and readdir() do igrab() if they find a F-d-c entry
237  *			and consider negative result as cache miss.
238  */
239 
240 static void fat_hash_init(struct super_block *sb)
241 {
242 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
243 	int i;
244 
245 	spin_lock_init(&sbi->inode_hash_lock);
246 	for (i = 0; i < FAT_HASH_SIZE; i++)
247 		INIT_HLIST_HEAD(&sbi->inode_hashtable[i]);
248 }
249 
250 static inline unsigned long fat_hash(struct super_block *sb, loff_t i_pos)
251 {
252 	unsigned long tmp = (unsigned long)i_pos | (unsigned long) sb;
253 	tmp = tmp + (tmp >> FAT_HASH_BITS) + (tmp >> FAT_HASH_BITS * 2);
254 	return tmp & FAT_HASH_MASK;
255 }
256 
257 void fat_attach(struct inode *inode, loff_t i_pos)
258 {
259 	struct super_block *sb = inode->i_sb;
260 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
261 
262 	spin_lock(&sbi->inode_hash_lock);
263 	MSDOS_I(inode)->i_pos = i_pos;
264 	hlist_add_head(&MSDOS_I(inode)->i_fat_hash,
265 			sbi->inode_hashtable + fat_hash(sb, i_pos));
266 	spin_unlock(&sbi->inode_hash_lock);
267 }
268 
269 EXPORT_SYMBOL_GPL(fat_attach);
270 
271 void fat_detach(struct inode *inode)
272 {
273 	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
274 	spin_lock(&sbi->inode_hash_lock);
275 	MSDOS_I(inode)->i_pos = 0;
276 	hlist_del_init(&MSDOS_I(inode)->i_fat_hash);
277 	spin_unlock(&sbi->inode_hash_lock);
278 }
279 
280 EXPORT_SYMBOL_GPL(fat_detach);
281 
282 struct inode *fat_iget(struct super_block *sb, loff_t i_pos)
283 {
284 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
285 	struct hlist_head *head = sbi->inode_hashtable + fat_hash(sb, i_pos);
286 	struct hlist_node *_p;
287 	struct msdos_inode_info *i;
288 	struct inode *inode = NULL;
289 
290 	spin_lock(&sbi->inode_hash_lock);
291 	hlist_for_each_entry(i, _p, head, i_fat_hash) {
292 		BUG_ON(i->vfs_inode.i_sb != sb);
293 		if (i->i_pos != i_pos)
294 			continue;
295 		inode = igrab(&i->vfs_inode);
296 		if (inode)
297 			break;
298 	}
299 	spin_unlock(&sbi->inode_hash_lock);
300 	return inode;
301 }
302 
303 static int is_exec(unsigned char *extension)
304 {
305 	unsigned char *exe_extensions = "EXECOMBAT", *walk;
306 
307 	for (walk = exe_extensions; *walk; walk += 3)
308 		if (!strncmp(extension, walk, 3))
309 			return 1;
310 	return 0;
311 }
312 
313 static int fat_calc_dir_size(struct inode *inode)
314 {
315 	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
316 	int ret, fclus, dclus;
317 
318 	inode->i_size = 0;
319 	if (MSDOS_I(inode)->i_start == 0)
320 		return 0;
321 
322 	ret = fat_get_cluster(inode, FAT_ENT_EOF, &fclus, &dclus);
323 	if (ret < 0)
324 		return ret;
325 	inode->i_size = (fclus + 1) << sbi->cluster_bits;
326 
327 	return 0;
328 }
329 
330 /* doesn't deal with root inode */
331 static int fat_fill_inode(struct inode *inode, struct msdos_dir_entry *de)
332 {
333 	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
334 	int error;
335 
336 	MSDOS_I(inode)->i_pos = 0;
337 	inode->i_uid = sbi->options.fs_uid;
338 	inode->i_gid = sbi->options.fs_gid;
339 	inode->i_version++;
340 	inode->i_generation = get_seconds();
341 
342 	if ((de->attr & ATTR_DIR) && !IS_FREE(de->name)) {
343 		inode->i_generation &= ~1;
344 		inode->i_mode = MSDOS_MKMODE(de->attr,
345 			S_IRWXUGO & ~sbi->options.fs_dmask) | S_IFDIR;
346 		inode->i_op = sbi->dir_ops;
347 		inode->i_fop = &fat_dir_operations;
348 
349 		MSDOS_I(inode)->i_start = le16_to_cpu(de->start);
350 		if (sbi->fat_bits == 32)
351 			MSDOS_I(inode)->i_start |= (le16_to_cpu(de->starthi) << 16);
352 
353 		MSDOS_I(inode)->i_logstart = MSDOS_I(inode)->i_start;
354 		error = fat_calc_dir_size(inode);
355 		if (error < 0)
356 			return error;
357 		MSDOS_I(inode)->mmu_private = inode->i_size;
358 
359 		inode->i_nlink = fat_subdirs(inode);
360 	} else { /* not a directory */
361 		inode->i_generation |= 1;
362 		inode->i_mode = MSDOS_MKMODE(de->attr,
363 		    ((sbi->options.showexec && !is_exec(de->name + 8))
364 			? S_IRUGO|S_IWUGO : S_IRWXUGO)
365 		    & ~sbi->options.fs_fmask) | S_IFREG;
366 		MSDOS_I(inode)->i_start = le16_to_cpu(de->start);
367 		if (sbi->fat_bits == 32)
368 			MSDOS_I(inode)->i_start |= (le16_to_cpu(de->starthi) << 16);
369 
370 		MSDOS_I(inode)->i_logstart = MSDOS_I(inode)->i_start;
371 		inode->i_size = le32_to_cpu(de->size);
372 		inode->i_op = &fat_file_inode_operations;
373 		inode->i_fop = &fat_file_operations;
374 		inode->i_mapping->a_ops = &fat_aops;
375 		MSDOS_I(inode)->mmu_private = inode->i_size;
376 	}
377 	if (de->attr & ATTR_SYS) {
378 		if (sbi->options.sys_immutable)
379 			inode->i_flags |= S_IMMUTABLE;
380 	}
381 	MSDOS_I(inode)->i_attrs = de->attr & ATTR_UNUSED;
382 	inode->i_blocks = ((inode->i_size + (sbi->cluster_size - 1))
383 			   & ~((loff_t)sbi->cluster_size - 1)) >> 9;
384 	inode->i_mtime.tv_sec =
385 		date_dos2unix(le16_to_cpu(de->time), le16_to_cpu(de->date));
386 	inode->i_mtime.tv_nsec = 0;
387 	if (sbi->options.isvfat) {
388 		int secs = de->ctime_cs / 100;
389 		int csecs = de->ctime_cs % 100;
390 		inode->i_ctime.tv_sec  =
391 			date_dos2unix(le16_to_cpu(de->ctime),
392 				      le16_to_cpu(de->cdate)) + secs;
393 		inode->i_ctime.tv_nsec = csecs * 10000000;
394 		inode->i_atime.tv_sec =
395 			date_dos2unix(0, le16_to_cpu(de->adate));
396 		inode->i_atime.tv_nsec = 0;
397 	} else
398 		inode->i_ctime = inode->i_atime = inode->i_mtime;
399 
400 	return 0;
401 }
402 
403 struct inode *fat_build_inode(struct super_block *sb,
404 			struct msdos_dir_entry *de, loff_t i_pos)
405 {
406 	struct inode *inode;
407 	int err;
408 
409 	inode = fat_iget(sb, i_pos);
410 	if (inode)
411 		goto out;
412 	inode = new_inode(sb);
413 	if (!inode) {
414 		inode = ERR_PTR(-ENOMEM);
415 		goto out;
416 	}
417 	inode->i_ino = iunique(sb, MSDOS_ROOT_INO);
418 	inode->i_version = 1;
419 	err = fat_fill_inode(inode, de);
420 	if (err) {
421 		iput(inode);
422 		inode = ERR_PTR(err);
423 		goto out;
424 	}
425 	fat_attach(inode, i_pos);
426 	insert_inode_hash(inode);
427 out:
428 	return inode;
429 }
430 
431 EXPORT_SYMBOL_GPL(fat_build_inode);
432 
433 static void fat_delete_inode(struct inode *inode)
434 {
435 	truncate_inode_pages(&inode->i_data, 0);
436 
437 	if (!is_bad_inode(inode)) {
438 		inode->i_size = 0;
439 		fat_truncate(inode);
440 	}
441 	clear_inode(inode);
442 }
443 
444 static void fat_clear_inode(struct inode *inode)
445 {
446 	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
447 
448 	if (is_bad_inode(inode))
449 		return;
450 	lock_kernel();
451 	spin_lock(&sbi->inode_hash_lock);
452 	fat_cache_inval_inode(inode);
453 	hlist_del_init(&MSDOS_I(inode)->i_fat_hash);
454 	spin_unlock(&sbi->inode_hash_lock);
455 	unlock_kernel();
456 }
457 
458 static void fat_write_super(struct super_block *sb)
459 {
460 	sb->s_dirt = 0;
461 
462 	if (!(sb->s_flags & MS_RDONLY))
463 		fat_clusters_flush(sb);
464 }
465 
466 static void fat_put_super(struct super_block *sb)
467 {
468 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
469 
470 	if (sbi->nls_disk) {
471 		unload_nls(sbi->nls_disk);
472 		sbi->nls_disk = NULL;
473 		sbi->options.codepage = fat_default_codepage;
474 	}
475 	if (sbi->nls_io) {
476 		unload_nls(sbi->nls_io);
477 		sbi->nls_io = NULL;
478 	}
479 	if (sbi->options.iocharset != fat_default_iocharset) {
480 		kfree(sbi->options.iocharset);
481 		sbi->options.iocharset = fat_default_iocharset;
482 	}
483 
484 	sb->s_fs_info = NULL;
485 	kfree(sbi);
486 }
487 
488 static struct kmem_cache *fat_inode_cachep;
489 
490 static struct inode *fat_alloc_inode(struct super_block *sb)
491 {
492 	struct msdos_inode_info *ei;
493 	ei = kmem_cache_alloc(fat_inode_cachep, GFP_KERNEL);
494 	if (!ei)
495 		return NULL;
496 	return &ei->vfs_inode;
497 }
498 
499 static void fat_destroy_inode(struct inode *inode)
500 {
501 	kmem_cache_free(fat_inode_cachep, MSDOS_I(inode));
502 }
503 
504 static void init_once(struct kmem_cache *cachep, void *foo)
505 {
506 	struct msdos_inode_info *ei = (struct msdos_inode_info *)foo;
507 
508 	spin_lock_init(&ei->cache_lru_lock);
509 	ei->nr_caches = 0;
510 	ei->cache_valid_id = FAT_CACHE_VALID + 1;
511 	INIT_LIST_HEAD(&ei->cache_lru);
512 	INIT_HLIST_NODE(&ei->i_fat_hash);
513 	inode_init_once(&ei->vfs_inode);
514 }
515 
516 static int __init fat_init_inodecache(void)
517 {
518 	fat_inode_cachep = kmem_cache_create("fat_inode_cache",
519 					     sizeof(struct msdos_inode_info),
520 					     0, (SLAB_RECLAIM_ACCOUNT|
521 						SLAB_MEM_SPREAD),
522 					     init_once);
523 	if (fat_inode_cachep == NULL)
524 		return -ENOMEM;
525 	return 0;
526 }
527 
528 static void __exit fat_destroy_inodecache(void)
529 {
530 	kmem_cache_destroy(fat_inode_cachep);
531 }
532 
533 static int fat_remount(struct super_block *sb, int *flags, char *data)
534 {
535 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
536 	*flags |= MS_NODIRATIME | (sbi->options.isvfat ? 0 : MS_NOATIME);
537 	return 0;
538 }
539 
540 static int fat_statfs(struct dentry *dentry, struct kstatfs *buf)
541 {
542 	struct msdos_sb_info *sbi = MSDOS_SB(dentry->d_sb);
543 
544 	/* If the count of free cluster is still unknown, counts it here. */
545 	if (sbi->free_clusters == -1) {
546 		int err = fat_count_free_clusters(dentry->d_sb);
547 		if (err)
548 			return err;
549 	}
550 
551 	buf->f_type = dentry->d_sb->s_magic;
552 	buf->f_bsize = sbi->cluster_size;
553 	buf->f_blocks = sbi->max_cluster - FAT_START_ENT;
554 	buf->f_bfree = sbi->free_clusters;
555 	buf->f_bavail = sbi->free_clusters;
556 	buf->f_namelen = sbi->options.isvfat ? 260 : 12;
557 
558 	return 0;
559 }
560 
561 static int fat_write_inode(struct inode *inode, int wait)
562 {
563 	struct super_block *sb = inode->i_sb;
564 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
565 	struct buffer_head *bh;
566 	struct msdos_dir_entry *raw_entry;
567 	loff_t i_pos;
568 	int err = 0;
569 
570 retry:
571 	i_pos = MSDOS_I(inode)->i_pos;
572 	if (inode->i_ino == MSDOS_ROOT_INO || !i_pos)
573 		return 0;
574 
575 	lock_kernel();
576 	bh = sb_bread(sb, i_pos >> sbi->dir_per_block_bits);
577 	if (!bh) {
578 		printk(KERN_ERR "FAT: unable to read inode block "
579 		       "for updating (i_pos %lld)\n", i_pos);
580 		err = -EIO;
581 		goto out;
582 	}
583 	spin_lock(&sbi->inode_hash_lock);
584 	if (i_pos != MSDOS_I(inode)->i_pos) {
585 		spin_unlock(&sbi->inode_hash_lock);
586 		brelse(bh);
587 		unlock_kernel();
588 		goto retry;
589 	}
590 
591 	raw_entry = &((struct msdos_dir_entry *) (bh->b_data))
592 	    [i_pos & (sbi->dir_per_block - 1)];
593 	if (S_ISDIR(inode->i_mode))
594 		raw_entry->size = 0;
595 	else
596 		raw_entry->size = cpu_to_le32(inode->i_size);
597 	raw_entry->attr = fat_attr(inode);
598 	raw_entry->start = cpu_to_le16(MSDOS_I(inode)->i_logstart);
599 	raw_entry->starthi = cpu_to_le16(MSDOS_I(inode)->i_logstart >> 16);
600 	fat_date_unix2dos(inode->i_mtime.tv_sec, &raw_entry->time, &raw_entry->date);
601 	if (sbi->options.isvfat) {
602 		__le16 atime;
603 		fat_date_unix2dos(inode->i_ctime.tv_sec,&raw_entry->ctime,&raw_entry->cdate);
604 		fat_date_unix2dos(inode->i_atime.tv_sec,&atime,&raw_entry->adate);
605 		raw_entry->ctime_cs = (inode->i_ctime.tv_sec & 1) * 100 +
606 			inode->i_ctime.tv_nsec / 10000000;
607 	}
608 	spin_unlock(&sbi->inode_hash_lock);
609 	mark_buffer_dirty(bh);
610 	if (wait)
611 		err = sync_dirty_buffer(bh);
612 	brelse(bh);
613 out:
614 	unlock_kernel();
615 	return err;
616 }
617 
618 int fat_sync_inode(struct inode *inode)
619 {
620 	return fat_write_inode(inode, 1);
621 }
622 
623 EXPORT_SYMBOL_GPL(fat_sync_inode);
624 
625 static int fat_show_options(struct seq_file *m, struct vfsmount *mnt);
626 static const struct super_operations fat_sops = {
627 	.alloc_inode	= fat_alloc_inode,
628 	.destroy_inode	= fat_destroy_inode,
629 	.write_inode	= fat_write_inode,
630 	.delete_inode	= fat_delete_inode,
631 	.put_super	= fat_put_super,
632 	.write_super	= fat_write_super,
633 	.statfs		= fat_statfs,
634 	.clear_inode	= fat_clear_inode,
635 	.remount_fs	= fat_remount,
636 
637 	.show_options	= fat_show_options,
638 };
639 
640 /*
641  * a FAT file handle with fhtype 3 is
642  *  0/  i_ino - for fast, reliable lookup if still in the cache
643  *  1/  i_generation - to see if i_ino is still valid
644  *          bit 0 == 0 iff directory
645  *  2/  i_pos(8-39) - if ino has changed, but still in cache
646  *  3/  i_pos(4-7)|i_logstart - to semi-verify inode found at i_pos
647  *  4/  i_pos(0-3)|parent->i_logstart - maybe used to hunt for the file on disc
648  *
649  * Hack for NFSv2: Maximum FAT entry number is 28bits and maximum
650  * i_pos is 40bits (blocknr(32) + dir offset(8)), so two 4bits
651  * of i_logstart is used to store the directory entry offset.
652  */
653 
654 static struct dentry *fat_fh_to_dentry(struct super_block *sb,
655 		struct fid *fid, int fh_len, int fh_type)
656 {
657 	struct inode *inode = NULL;
658 	struct dentry *result;
659 	u32 *fh = fid->raw;
660 
661 	if (fh_len < 5 || fh_type != 3)
662 		return NULL;
663 
664 	inode = ilookup(sb, fh[0]);
665 	if (!inode || inode->i_generation != fh[1]) {
666 		if (inode)
667 			iput(inode);
668 		inode = NULL;
669 	}
670 	if (!inode) {
671 		loff_t i_pos;
672 		int i_logstart = fh[3] & 0x0fffffff;
673 
674 		i_pos = (loff_t)fh[2] << 8;
675 		i_pos |= ((fh[3] >> 24) & 0xf0) | (fh[4] >> 28);
676 
677 		/* try 2 - see if i_pos is in F-d-c
678 		 * require i_logstart to be the same
679 		 * Will fail if you truncate and then re-write
680 		 */
681 
682 		inode = fat_iget(sb, i_pos);
683 		if (inode && MSDOS_I(inode)->i_logstart != i_logstart) {
684 			iput(inode);
685 			inode = NULL;
686 		}
687 	}
688 	if (!inode) {
689 		/* For now, do nothing
690 		 * What we could do is:
691 		 * follow the file starting at fh[4], and record
692 		 * the ".." entry, and the name of the fh[2] entry.
693 		 * The follow the ".." file finding the next step up.
694 		 * This way we build a path to the root of
695 		 * the tree. If this works, we lookup the path and so
696 		 * get this inode into the cache.
697 		 * Finally try the fat_iget lookup again
698 		 * If that fails, then weare totally out of luck
699 		 * But all that is for another day
700 		 */
701 	}
702 	if (!inode)
703 		return ERR_PTR(-ESTALE);
704 
705 
706 	/* now to find a dentry.
707 	 * If possible, get a well-connected one
708 	 */
709 	result = d_alloc_anon(inode);
710 	if (result == NULL) {
711 		iput(inode);
712 		return ERR_PTR(-ENOMEM);
713 	}
714 	result->d_op = sb->s_root->d_op;
715 	return result;
716 }
717 
718 static int
719 fat_encode_fh(struct dentry *de, __u32 *fh, int *lenp, int connectable)
720 {
721 	int len = *lenp;
722 	struct inode *inode =  de->d_inode;
723 	u32 ipos_h, ipos_m, ipos_l;
724 
725 	if (len < 5)
726 		return 255; /* no room */
727 
728 	ipos_h = MSDOS_I(inode)->i_pos >> 8;
729 	ipos_m = (MSDOS_I(inode)->i_pos & 0xf0) << 24;
730 	ipos_l = (MSDOS_I(inode)->i_pos & 0x0f) << 28;
731 	*lenp = 5;
732 	fh[0] = inode->i_ino;
733 	fh[1] = inode->i_generation;
734 	fh[2] = ipos_h;
735 	fh[3] = ipos_m | MSDOS_I(inode)->i_logstart;
736 	spin_lock(&de->d_lock);
737 	fh[4] = ipos_l | MSDOS_I(de->d_parent->d_inode)->i_logstart;
738 	spin_unlock(&de->d_lock);
739 	return 3;
740 }
741 
742 static struct dentry *fat_get_parent(struct dentry *child)
743 {
744 	struct buffer_head *bh;
745 	struct msdos_dir_entry *de;
746 	loff_t i_pos;
747 	struct dentry *parent;
748 	struct inode *inode;
749 	int err;
750 
751 	lock_kernel();
752 
753 	err = fat_get_dotdot_entry(child->d_inode, &bh, &de, &i_pos);
754 	if (err) {
755 		parent = ERR_PTR(err);
756 		goto out;
757 	}
758 	inode = fat_build_inode(child->d_sb, de, i_pos);
759 	brelse(bh);
760 	if (IS_ERR(inode)) {
761 		parent = ERR_CAST(inode);
762 		goto out;
763 	}
764 	parent = d_alloc_anon(inode);
765 	if (!parent) {
766 		iput(inode);
767 		parent = ERR_PTR(-ENOMEM);
768 	}
769 out:
770 	unlock_kernel();
771 
772 	return parent;
773 }
774 
775 static const struct export_operations fat_export_ops = {
776 	.encode_fh	= fat_encode_fh,
777 	.fh_to_dentry	= fat_fh_to_dentry,
778 	.get_parent	= fat_get_parent,
779 };
780 
781 static int fat_show_options(struct seq_file *m, struct vfsmount *mnt)
782 {
783 	struct msdos_sb_info *sbi = MSDOS_SB(mnt->mnt_sb);
784 	struct fat_mount_options *opts = &sbi->options;
785 	int isvfat = opts->isvfat;
786 
787 	if (opts->fs_uid != 0)
788 		seq_printf(m, ",uid=%u", opts->fs_uid);
789 	if (opts->fs_gid != 0)
790 		seq_printf(m, ",gid=%u", opts->fs_gid);
791 	seq_printf(m, ",fmask=%04o", opts->fs_fmask);
792 	seq_printf(m, ",dmask=%04o", opts->fs_dmask);
793 	if (sbi->nls_disk)
794 		seq_printf(m, ",codepage=%s", sbi->nls_disk->charset);
795 	if (isvfat) {
796 		if (sbi->nls_io)
797 			seq_printf(m, ",iocharset=%s", sbi->nls_io->charset);
798 
799 		switch (opts->shortname) {
800 		case VFAT_SFN_DISPLAY_WIN95 | VFAT_SFN_CREATE_WIN95:
801 			seq_puts(m, ",shortname=win95");
802 			break;
803 		case VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WINNT:
804 			seq_puts(m, ",shortname=winnt");
805 			break;
806 		case VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WIN95:
807 			seq_puts(m, ",shortname=mixed");
808 			break;
809 		case VFAT_SFN_DISPLAY_LOWER | VFAT_SFN_CREATE_WIN95:
810 			/* seq_puts(m, ",shortname=lower"); */
811 			break;
812 		default:
813 			seq_puts(m, ",shortname=unknown");
814 			break;
815 		}
816 	}
817 	if (opts->name_check != 'n')
818 		seq_printf(m, ",check=%c", opts->name_check);
819 	if (opts->usefree)
820 		seq_puts(m, ",usefree");
821 	if (opts->quiet)
822 		seq_puts(m, ",quiet");
823 	if (opts->showexec)
824 		seq_puts(m, ",showexec");
825 	if (opts->sys_immutable)
826 		seq_puts(m, ",sys_immutable");
827 	if (!isvfat) {
828 		if (opts->dotsOK)
829 			seq_puts(m, ",dotsOK=yes");
830 		if (opts->nocase)
831 			seq_puts(m, ",nocase");
832 	} else {
833 		if (opts->utf8)
834 			seq_puts(m, ",utf8");
835 		if (opts->unicode_xlate)
836 			seq_puts(m, ",uni_xlate");
837 		if (!opts->numtail)
838 			seq_puts(m, ",nonumtail");
839 	}
840 	if (sbi->options.flush)
841 		seq_puts(m, ",flush");
842 
843 	return 0;
844 }
845 
846 enum {
847 	Opt_check_n, Opt_check_r, Opt_check_s, Opt_uid, Opt_gid,
848 	Opt_umask, Opt_dmask, Opt_fmask, Opt_codepage, Opt_usefree, Opt_nocase,
849 	Opt_quiet, Opt_showexec, Opt_debug, Opt_immutable,
850 	Opt_dots, Opt_nodots,
851 	Opt_charset, Opt_shortname_lower, Opt_shortname_win95,
852 	Opt_shortname_winnt, Opt_shortname_mixed, Opt_utf8_no, Opt_utf8_yes,
853 	Opt_uni_xl_no, Opt_uni_xl_yes, Opt_nonumtail_no, Opt_nonumtail_yes,
854 	Opt_obsolate, Opt_flush, Opt_err,
855 };
856 
857 static match_table_t fat_tokens = {
858 	{Opt_check_r, "check=relaxed"},
859 	{Opt_check_s, "check=strict"},
860 	{Opt_check_n, "check=normal"},
861 	{Opt_check_r, "check=r"},
862 	{Opt_check_s, "check=s"},
863 	{Opt_check_n, "check=n"},
864 	{Opt_uid, "uid=%u"},
865 	{Opt_gid, "gid=%u"},
866 	{Opt_umask, "umask=%o"},
867 	{Opt_dmask, "dmask=%o"},
868 	{Opt_fmask, "fmask=%o"},
869 	{Opt_codepage, "codepage=%u"},
870 	{Opt_usefree, "usefree"},
871 	{Opt_nocase, "nocase"},
872 	{Opt_quiet, "quiet"},
873 	{Opt_showexec, "showexec"},
874 	{Opt_debug, "debug"},
875 	{Opt_immutable, "sys_immutable"},
876 	{Opt_obsolate, "conv=binary"},
877 	{Opt_obsolate, "conv=text"},
878 	{Opt_obsolate, "conv=auto"},
879 	{Opt_obsolate, "conv=b"},
880 	{Opt_obsolate, "conv=t"},
881 	{Opt_obsolate, "conv=a"},
882 	{Opt_obsolate, "fat=%u"},
883 	{Opt_obsolate, "blocksize=%u"},
884 	{Opt_obsolate, "cvf_format=%20s"},
885 	{Opt_obsolate, "cvf_options=%100s"},
886 	{Opt_obsolate, "posix"},
887 	{Opt_flush, "flush"},
888 	{Opt_err, NULL},
889 };
890 static match_table_t msdos_tokens = {
891 	{Opt_nodots, "nodots"},
892 	{Opt_nodots, "dotsOK=no"},
893 	{Opt_dots, "dots"},
894 	{Opt_dots, "dotsOK=yes"},
895 	{Opt_err, NULL}
896 };
897 static match_table_t vfat_tokens = {
898 	{Opt_charset, "iocharset=%s"},
899 	{Opt_shortname_lower, "shortname=lower"},
900 	{Opt_shortname_win95, "shortname=win95"},
901 	{Opt_shortname_winnt, "shortname=winnt"},
902 	{Opt_shortname_mixed, "shortname=mixed"},
903 	{Opt_utf8_no, "utf8=0"},		/* 0 or no or false */
904 	{Opt_utf8_no, "utf8=no"},
905 	{Opt_utf8_no, "utf8=false"},
906 	{Opt_utf8_yes, "utf8=1"},		/* empty or 1 or yes or true */
907 	{Opt_utf8_yes, "utf8=yes"},
908 	{Opt_utf8_yes, "utf8=true"},
909 	{Opt_utf8_yes, "utf8"},
910 	{Opt_uni_xl_no, "uni_xlate=0"},		/* 0 or no or false */
911 	{Opt_uni_xl_no, "uni_xlate=no"},
912 	{Opt_uni_xl_no, "uni_xlate=false"},
913 	{Opt_uni_xl_yes, "uni_xlate=1"},	/* empty or 1 or yes or true */
914 	{Opt_uni_xl_yes, "uni_xlate=yes"},
915 	{Opt_uni_xl_yes, "uni_xlate=true"},
916 	{Opt_uni_xl_yes, "uni_xlate"},
917 	{Opt_nonumtail_no, "nonumtail=0"},	/* 0 or no or false */
918 	{Opt_nonumtail_no, "nonumtail=no"},
919 	{Opt_nonumtail_no, "nonumtail=false"},
920 	{Opt_nonumtail_yes, "nonumtail=1"},	/* empty or 1 or yes or true */
921 	{Opt_nonumtail_yes, "nonumtail=yes"},
922 	{Opt_nonumtail_yes, "nonumtail=true"},
923 	{Opt_nonumtail_yes, "nonumtail"},
924 	{Opt_err, NULL}
925 };
926 
927 static int parse_options(char *options, int is_vfat, int silent, int *debug,
928 			 struct fat_mount_options *opts)
929 {
930 	char *p;
931 	substring_t args[MAX_OPT_ARGS];
932 	int option;
933 	char *iocharset;
934 
935 	opts->isvfat = is_vfat;
936 
937 	opts->fs_uid = current->uid;
938 	opts->fs_gid = current->gid;
939 	opts->fs_fmask = opts->fs_dmask = current->fs->umask;
940 	opts->codepage = fat_default_codepage;
941 	opts->iocharset = fat_default_iocharset;
942 	if (is_vfat)
943 		opts->shortname = VFAT_SFN_DISPLAY_LOWER|VFAT_SFN_CREATE_WIN95;
944 	else
945 		opts->shortname = 0;
946 	opts->name_check = 'n';
947 	opts->quiet = opts->showexec = opts->sys_immutable = opts->dotsOK =  0;
948 	opts->utf8 = opts->unicode_xlate = 0;
949 	opts->numtail = 1;
950 	opts->usefree = opts->nocase = 0;
951 	*debug = 0;
952 
953 	if (!options)
954 		return 0;
955 
956 	while ((p = strsep(&options, ",")) != NULL) {
957 		int token;
958 		if (!*p)
959 			continue;
960 
961 		token = match_token(p, fat_tokens, args);
962 		if (token == Opt_err) {
963 			if (is_vfat)
964 				token = match_token(p, vfat_tokens, args);
965 			else
966 				token = match_token(p, msdos_tokens, args);
967 		}
968 		switch (token) {
969 		case Opt_check_s:
970 			opts->name_check = 's';
971 			break;
972 		case Opt_check_r:
973 			opts->name_check = 'r';
974 			break;
975 		case Opt_check_n:
976 			opts->name_check = 'n';
977 			break;
978 		case Opt_usefree:
979 			opts->usefree = 1;
980 			break;
981 		case Opt_nocase:
982 			if (!is_vfat)
983 				opts->nocase = 1;
984 			else {
985 				/* for backward compatibility */
986 				opts->shortname = VFAT_SFN_DISPLAY_WIN95
987 					| VFAT_SFN_CREATE_WIN95;
988 			}
989 			break;
990 		case Opt_quiet:
991 			opts->quiet = 1;
992 			break;
993 		case Opt_showexec:
994 			opts->showexec = 1;
995 			break;
996 		case Opt_debug:
997 			*debug = 1;
998 			break;
999 		case Opt_immutable:
1000 			opts->sys_immutable = 1;
1001 			break;
1002 		case Opt_uid:
1003 			if (match_int(&args[0], &option))
1004 				return 0;
1005 			opts->fs_uid = option;
1006 			break;
1007 		case Opt_gid:
1008 			if (match_int(&args[0], &option))
1009 				return 0;
1010 			opts->fs_gid = option;
1011 			break;
1012 		case Opt_umask:
1013 			if (match_octal(&args[0], &option))
1014 				return 0;
1015 			opts->fs_fmask = opts->fs_dmask = option;
1016 			break;
1017 		case Opt_dmask:
1018 			if (match_octal(&args[0], &option))
1019 				return 0;
1020 			opts->fs_dmask = option;
1021 			break;
1022 		case Opt_fmask:
1023 			if (match_octal(&args[0], &option))
1024 				return 0;
1025 			opts->fs_fmask = option;
1026 			break;
1027 		case Opt_codepage:
1028 			if (match_int(&args[0], &option))
1029 				return 0;
1030 			opts->codepage = option;
1031 			break;
1032 		case Opt_flush:
1033 			opts->flush = 1;
1034 			break;
1035 
1036 		/* msdos specific */
1037 		case Opt_dots:
1038 			opts->dotsOK = 1;
1039 			break;
1040 		case Opt_nodots:
1041 			opts->dotsOK = 0;
1042 			break;
1043 
1044 		/* vfat specific */
1045 		case Opt_charset:
1046 			if (opts->iocharset != fat_default_iocharset)
1047 				kfree(opts->iocharset);
1048 			iocharset = match_strdup(&args[0]);
1049 			if (!iocharset)
1050 				return -ENOMEM;
1051 			opts->iocharset = iocharset;
1052 			break;
1053 		case Opt_shortname_lower:
1054 			opts->shortname = VFAT_SFN_DISPLAY_LOWER
1055 					| VFAT_SFN_CREATE_WIN95;
1056 			break;
1057 		case Opt_shortname_win95:
1058 			opts->shortname = VFAT_SFN_DISPLAY_WIN95
1059 					| VFAT_SFN_CREATE_WIN95;
1060 			break;
1061 		case Opt_shortname_winnt:
1062 			opts->shortname = VFAT_SFN_DISPLAY_WINNT
1063 					| VFAT_SFN_CREATE_WINNT;
1064 			break;
1065 		case Opt_shortname_mixed:
1066 			opts->shortname = VFAT_SFN_DISPLAY_WINNT
1067 					| VFAT_SFN_CREATE_WIN95;
1068 			break;
1069 		case Opt_utf8_no:		/* 0 or no or false */
1070 			opts->utf8 = 0;
1071 			break;
1072 		case Opt_utf8_yes:		/* empty or 1 or yes or true */
1073 			opts->utf8 = 1;
1074 			break;
1075 		case Opt_uni_xl_no:		/* 0 or no or false */
1076 			opts->unicode_xlate = 0;
1077 			break;
1078 		case Opt_uni_xl_yes:		/* empty or 1 or yes or true */
1079 			opts->unicode_xlate = 1;
1080 			break;
1081 		case Opt_nonumtail_no:		/* 0 or no or false */
1082 			opts->numtail = 1;	/* negated option */
1083 			break;
1084 		case Opt_nonumtail_yes:		/* empty or 1 or yes or true */
1085 			opts->numtail = 0;	/* negated option */
1086 			break;
1087 
1088 		/* obsolete mount options */
1089 		case Opt_obsolate:
1090 			printk(KERN_INFO "FAT: \"%s\" option is obsolete, "
1091 			       "not supported now\n", p);
1092 			break;
1093 		/* unknown option */
1094 		default:
1095 			if (!silent) {
1096 				printk(KERN_ERR
1097 				       "FAT: Unrecognized mount option \"%s\" "
1098 				       "or missing value\n", p);
1099 			}
1100 			return -EINVAL;
1101 		}
1102 	}
1103 	/* UTF-8 doesn't provide FAT semantics */
1104 	if (!strcmp(opts->iocharset, "utf8")) {
1105 		printk(KERN_ERR "FAT: utf8 is not a recommended IO charset"
1106 		       " for FAT filesystems, filesystem will be case sensitive!\n");
1107 	}
1108 
1109 	if (opts->unicode_xlate)
1110 		opts->utf8 = 0;
1111 
1112 	return 0;
1113 }
1114 
1115 static int fat_read_root(struct inode *inode)
1116 {
1117 	struct super_block *sb = inode->i_sb;
1118 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
1119 	int error;
1120 
1121 	MSDOS_I(inode)->i_pos = 0;
1122 	inode->i_uid = sbi->options.fs_uid;
1123 	inode->i_gid = sbi->options.fs_gid;
1124 	inode->i_version++;
1125 	inode->i_generation = 0;
1126 	inode->i_mode = (S_IRWXUGO & ~sbi->options.fs_dmask) | S_IFDIR;
1127 	inode->i_op = sbi->dir_ops;
1128 	inode->i_fop = &fat_dir_operations;
1129 	if (sbi->fat_bits == 32) {
1130 		MSDOS_I(inode)->i_start = sbi->root_cluster;
1131 		error = fat_calc_dir_size(inode);
1132 		if (error < 0)
1133 			return error;
1134 	} else {
1135 		MSDOS_I(inode)->i_start = 0;
1136 		inode->i_size = sbi->dir_entries * sizeof(struct msdos_dir_entry);
1137 	}
1138 	inode->i_blocks = ((inode->i_size + (sbi->cluster_size - 1))
1139 			   & ~((loff_t)sbi->cluster_size - 1)) >> 9;
1140 	MSDOS_I(inode)->i_logstart = 0;
1141 	MSDOS_I(inode)->mmu_private = inode->i_size;
1142 
1143 	MSDOS_I(inode)->i_attrs = ATTR_NONE;
1144 	inode->i_mtime.tv_sec = inode->i_atime.tv_sec = inode->i_ctime.tv_sec = 0;
1145 	inode->i_mtime.tv_nsec = inode->i_atime.tv_nsec = inode->i_ctime.tv_nsec = 0;
1146 	inode->i_nlink = fat_subdirs(inode)+2;
1147 
1148 	return 0;
1149 }
1150 
1151 /*
1152  * Read the super block of an MS-DOS FS.
1153  */
1154 int fat_fill_super(struct super_block *sb, void *data, int silent,
1155 		   const struct inode_operations *fs_dir_inode_ops, int isvfat)
1156 {
1157 	struct inode *root_inode = NULL;
1158 	struct buffer_head *bh;
1159 	struct fat_boot_sector *b;
1160 	struct msdos_sb_info *sbi;
1161 	u16 logical_sector_size;
1162 	u32 total_sectors, total_clusters, fat_clusters, rootdir_sectors;
1163 	int debug;
1164 	unsigned int media;
1165 	long error;
1166 	char buf[50];
1167 
1168 	sbi = kzalloc(sizeof(struct msdos_sb_info), GFP_KERNEL);
1169 	if (!sbi)
1170 		return -ENOMEM;
1171 	sb->s_fs_info = sbi;
1172 
1173 	sb->s_flags |= MS_NODIRATIME;
1174 	sb->s_magic = MSDOS_SUPER_MAGIC;
1175 	sb->s_op = &fat_sops;
1176 	sb->s_export_op = &fat_export_ops;
1177 	sbi->dir_ops = fs_dir_inode_ops;
1178 
1179 	error = parse_options(data, isvfat, silent, &debug, &sbi->options);
1180 	if (error)
1181 		goto out_fail;
1182 
1183 	error = -EIO;
1184 	sb_min_blocksize(sb, 512);
1185 	bh = sb_bread(sb, 0);
1186 	if (bh == NULL) {
1187 		printk(KERN_ERR "FAT: unable to read boot sector\n");
1188 		goto out_fail;
1189 	}
1190 
1191 	b = (struct fat_boot_sector *) bh->b_data;
1192 	if (!b->reserved) {
1193 		if (!silent)
1194 			printk(KERN_ERR "FAT: bogus number of reserved sectors\n");
1195 		brelse(bh);
1196 		goto out_invalid;
1197 	}
1198 	if (!b->fats) {
1199 		if (!silent)
1200 			printk(KERN_ERR "FAT: bogus number of FAT structure\n");
1201 		brelse(bh);
1202 		goto out_invalid;
1203 	}
1204 
1205 	/*
1206 	 * Earlier we checked here that b->secs_track and b->head are nonzero,
1207 	 * but it turns out valid FAT filesystems can have zero there.
1208 	 */
1209 
1210 	media = b->media;
1211 	if (!FAT_VALID_MEDIA(media)) {
1212 		if (!silent)
1213 			printk(KERN_ERR "FAT: invalid media value (0x%02x)\n",
1214 			       media);
1215 		brelse(bh);
1216 		goto out_invalid;
1217 	}
1218 	logical_sector_size =
1219 		le16_to_cpu(get_unaligned((__le16 *)&b->sector_size));
1220 	if (!is_power_of_2(logical_sector_size)
1221 	    || (logical_sector_size < 512)
1222 	    || (PAGE_CACHE_SIZE < logical_sector_size)) {
1223 		if (!silent)
1224 			printk(KERN_ERR "FAT: bogus logical sector size %u\n",
1225 			       logical_sector_size);
1226 		brelse(bh);
1227 		goto out_invalid;
1228 	}
1229 	sbi->sec_per_clus = b->sec_per_clus;
1230 	if (!is_power_of_2(sbi->sec_per_clus)) {
1231 		if (!silent)
1232 			printk(KERN_ERR "FAT: bogus sectors per cluster %u\n",
1233 			       sbi->sec_per_clus);
1234 		brelse(bh);
1235 		goto out_invalid;
1236 	}
1237 
1238 	if (logical_sector_size < sb->s_blocksize) {
1239 		printk(KERN_ERR "FAT: logical sector size too small for device"
1240 		       " (logical sector size = %u)\n", logical_sector_size);
1241 		brelse(bh);
1242 		goto out_fail;
1243 	}
1244 	if (logical_sector_size > sb->s_blocksize) {
1245 		brelse(bh);
1246 
1247 		if (!sb_set_blocksize(sb, logical_sector_size)) {
1248 			printk(KERN_ERR "FAT: unable to set blocksize %u\n",
1249 			       logical_sector_size);
1250 			goto out_fail;
1251 		}
1252 		bh = sb_bread(sb, 0);
1253 		if (bh == NULL) {
1254 			printk(KERN_ERR "FAT: unable to read boot sector"
1255 			       " (logical sector size = %lu)\n",
1256 			       sb->s_blocksize);
1257 			goto out_fail;
1258 		}
1259 		b = (struct fat_boot_sector *) bh->b_data;
1260 	}
1261 
1262 	sbi->cluster_size = sb->s_blocksize * sbi->sec_per_clus;
1263 	sbi->cluster_bits = ffs(sbi->cluster_size) - 1;
1264 	sbi->fats = b->fats;
1265 	sbi->fat_bits = 0;		/* Don't know yet */
1266 	sbi->fat_start = le16_to_cpu(b->reserved);
1267 	sbi->fat_length = le16_to_cpu(b->fat_length);
1268 	sbi->root_cluster = 0;
1269 	sbi->free_clusters = -1;	/* Don't know yet */
1270 	sbi->prev_free = FAT_START_ENT;
1271 
1272 	if (!sbi->fat_length && b->fat32_length) {
1273 		struct fat_boot_fsinfo *fsinfo;
1274 		struct buffer_head *fsinfo_bh;
1275 
1276 		/* Must be FAT32 */
1277 		sbi->fat_bits = 32;
1278 		sbi->fat_length = le32_to_cpu(b->fat32_length);
1279 		sbi->root_cluster = le32_to_cpu(b->root_cluster);
1280 
1281 		sb->s_maxbytes = 0xffffffff;
1282 
1283 		/* MC - if info_sector is 0, don't multiply by 0 */
1284 		sbi->fsinfo_sector = le16_to_cpu(b->info_sector);
1285 		if (sbi->fsinfo_sector == 0)
1286 			sbi->fsinfo_sector = 1;
1287 
1288 		fsinfo_bh = sb_bread(sb, sbi->fsinfo_sector);
1289 		if (fsinfo_bh == NULL) {
1290 			printk(KERN_ERR "FAT: bread failed, FSINFO block"
1291 			       " (sector = %lu)\n", sbi->fsinfo_sector);
1292 			brelse(bh);
1293 			goto out_fail;
1294 		}
1295 
1296 		fsinfo = (struct fat_boot_fsinfo *)fsinfo_bh->b_data;
1297 		if (!IS_FSINFO(fsinfo)) {
1298 			printk(KERN_WARNING "FAT: Invalid FSINFO signature: "
1299 			       "0x%08x, 0x%08x (sector = %lu)\n",
1300 			       le32_to_cpu(fsinfo->signature1),
1301 			       le32_to_cpu(fsinfo->signature2),
1302 			       sbi->fsinfo_sector);
1303 		} else {
1304 			if (sbi->options.usefree)
1305 				sbi->free_clusters =
1306 					le32_to_cpu(fsinfo->free_clusters);
1307 			sbi->prev_free = le32_to_cpu(fsinfo->next_cluster);
1308 		}
1309 
1310 		brelse(fsinfo_bh);
1311 	}
1312 
1313 	sbi->dir_per_block = sb->s_blocksize / sizeof(struct msdos_dir_entry);
1314 	sbi->dir_per_block_bits = ffs(sbi->dir_per_block) - 1;
1315 
1316 	sbi->dir_start = sbi->fat_start + sbi->fats * sbi->fat_length;
1317 	sbi->dir_entries =
1318 		le16_to_cpu(get_unaligned((__le16 *)&b->dir_entries));
1319 	if (sbi->dir_entries & (sbi->dir_per_block - 1)) {
1320 		if (!silent)
1321 			printk(KERN_ERR "FAT: bogus directroy-entries per block"
1322 			       " (%u)\n", sbi->dir_entries);
1323 		brelse(bh);
1324 		goto out_invalid;
1325 	}
1326 
1327 	rootdir_sectors = sbi->dir_entries
1328 		* sizeof(struct msdos_dir_entry) / sb->s_blocksize;
1329 	sbi->data_start = sbi->dir_start + rootdir_sectors;
1330 	total_sectors = le16_to_cpu(get_unaligned((__le16 *)&b->sectors));
1331 	if (total_sectors == 0)
1332 		total_sectors = le32_to_cpu(b->total_sect);
1333 
1334 	total_clusters = (total_sectors - sbi->data_start) / sbi->sec_per_clus;
1335 
1336 	if (sbi->fat_bits != 32)
1337 		sbi->fat_bits = (total_clusters > MAX_FAT12) ? 16 : 12;
1338 
1339 	/* check that FAT table does not overflow */
1340 	fat_clusters = sbi->fat_length * sb->s_blocksize * 8 / sbi->fat_bits;
1341 	total_clusters = min(total_clusters, fat_clusters - FAT_START_ENT);
1342 	if (total_clusters > MAX_FAT(sb)) {
1343 		if (!silent)
1344 			printk(KERN_ERR "FAT: count of clusters too big (%u)\n",
1345 			       total_clusters);
1346 		brelse(bh);
1347 		goto out_invalid;
1348 	}
1349 
1350 	sbi->max_cluster = total_clusters + FAT_START_ENT;
1351 	/* check the free_clusters, it's not necessarily correct */
1352 	if (sbi->free_clusters != -1 && sbi->free_clusters > total_clusters)
1353 		sbi->free_clusters = -1;
1354 	/* check the prev_free, it's not necessarily correct */
1355 	sbi->prev_free %= sbi->max_cluster;
1356 	if (sbi->prev_free < FAT_START_ENT)
1357 		sbi->prev_free = FAT_START_ENT;
1358 
1359 	brelse(bh);
1360 
1361 	/* set up enough so that it can read an inode */
1362 	fat_hash_init(sb);
1363 	fat_ent_access_init(sb);
1364 
1365 	/*
1366 	 * The low byte of FAT's first entry must have same value with
1367 	 * media-field.  But in real world, too many devices is
1368 	 * writing wrong value.  So, removed that validity check.
1369 	 *
1370 	 * if (FAT_FIRST_ENT(sb, media) != first)
1371 	 */
1372 
1373 	error = -EINVAL;
1374 	sprintf(buf, "cp%d", sbi->options.codepage);
1375 	sbi->nls_disk = load_nls(buf);
1376 	if (!sbi->nls_disk) {
1377 		printk(KERN_ERR "FAT: codepage %s not found\n", buf);
1378 		goto out_fail;
1379 	}
1380 
1381 	/* FIXME: utf8 is using iocharset for upper/lower conversion */
1382 	if (sbi->options.isvfat) {
1383 		sbi->nls_io = load_nls(sbi->options.iocharset);
1384 		if (!sbi->nls_io) {
1385 			printk(KERN_ERR "FAT: IO charset %s not found\n",
1386 			       sbi->options.iocharset);
1387 			goto out_fail;
1388 		}
1389 	}
1390 
1391 	error = -ENOMEM;
1392 	root_inode = new_inode(sb);
1393 	if (!root_inode)
1394 		goto out_fail;
1395 	root_inode->i_ino = MSDOS_ROOT_INO;
1396 	root_inode->i_version = 1;
1397 	error = fat_read_root(root_inode);
1398 	if (error < 0)
1399 		goto out_fail;
1400 	error = -ENOMEM;
1401 	insert_inode_hash(root_inode);
1402 	sb->s_root = d_alloc_root(root_inode);
1403 	if (!sb->s_root) {
1404 		printk(KERN_ERR "FAT: get root inode failed\n");
1405 		goto out_fail;
1406 	}
1407 
1408 	return 0;
1409 
1410 out_invalid:
1411 	error = -EINVAL;
1412 	if (!silent)
1413 		printk(KERN_INFO "VFS: Can't find a valid FAT filesystem"
1414 		       " on dev %s.\n", sb->s_id);
1415 
1416 out_fail:
1417 	if (root_inode)
1418 		iput(root_inode);
1419 	if (sbi->nls_io)
1420 		unload_nls(sbi->nls_io);
1421 	if (sbi->nls_disk)
1422 		unload_nls(sbi->nls_disk);
1423 	if (sbi->options.iocharset != fat_default_iocharset)
1424 		kfree(sbi->options.iocharset);
1425 	sb->s_fs_info = NULL;
1426 	kfree(sbi);
1427 	return error;
1428 }
1429 
1430 EXPORT_SYMBOL_GPL(fat_fill_super);
1431 
1432 /*
1433  * helper function for fat_flush_inodes.  This writes both the inode
1434  * and the file data blocks, waiting for in flight data blocks before
1435  * the start of the call.  It does not wait for any io started
1436  * during the call
1437  */
1438 static int writeback_inode(struct inode *inode)
1439 {
1440 
1441 	int ret;
1442 	struct address_space *mapping = inode->i_mapping;
1443 	struct writeback_control wbc = {
1444 	       .sync_mode = WB_SYNC_NONE,
1445 	      .nr_to_write = 0,
1446 	};
1447 	/* if we used WB_SYNC_ALL, sync_inode waits for the io for the
1448 	* inode to finish.  So WB_SYNC_NONE is sent down to sync_inode
1449 	* and filemap_fdatawrite is used for the data blocks
1450 	*/
1451 	ret = sync_inode(inode, &wbc);
1452 	if (!ret)
1453 	       ret = filemap_fdatawrite(mapping);
1454 	return ret;
1455 }
1456 
1457 /*
1458  * write data and metadata corresponding to i1 and i2.  The io is
1459  * started but we do not wait for any of it to finish.
1460  *
1461  * filemap_flush is used for the block device, so if there is a dirty
1462  * page for a block already in flight, we will not wait and start the
1463  * io over again
1464  */
1465 int fat_flush_inodes(struct super_block *sb, struct inode *i1, struct inode *i2)
1466 {
1467 	int ret = 0;
1468 	if (!MSDOS_SB(sb)->options.flush)
1469 		return 0;
1470 	if (i1)
1471 		ret = writeback_inode(i1);
1472 	if (!ret && i2)
1473 		ret = writeback_inode(i2);
1474 	if (!ret) {
1475 		struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping;
1476 		ret = filemap_flush(mapping);
1477 	}
1478 	return ret;
1479 }
1480 EXPORT_SYMBOL_GPL(fat_flush_inodes);
1481 
1482 static int __init init_fat_fs(void)
1483 {
1484 	int err;
1485 
1486 	err = fat_cache_init();
1487 	if (err)
1488 		return err;
1489 
1490 	err = fat_init_inodecache();
1491 	if (err)
1492 		goto failed;
1493 
1494 	return 0;
1495 
1496 failed:
1497 	fat_cache_destroy();
1498 	return err;
1499 }
1500 
1501 static void __exit exit_fat_fs(void)
1502 {
1503 	fat_cache_destroy();
1504 	fat_destroy_inodecache();
1505 }
1506 
1507 module_init(init_fat_fs)
1508 module_exit(exit_fat_fs)
1509 
1510 MODULE_LICENSE("GPL");
1511