xref: /openbmc/linux/fs/fat/inode.c (revision e868d61272caa648214046a096e5a6bfc068dc8c)
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/mount.h>
24 #include <linux/vfs.h>
25 #include <linux/parser.h>
26 #include <linux/uio.h>
27 #include <linux/writeback.h>
28 #include <linux/log2.h>
29 #include <asm/unaligned.h>
30 
31 #ifndef CONFIG_FAT_DEFAULT_IOCHARSET
32 /* if user don't select VFAT, this is undefined. */
33 #define CONFIG_FAT_DEFAULT_IOCHARSET	""
34 #endif
35 
36 static int fat_default_codepage = CONFIG_FAT_DEFAULT_CODEPAGE;
37 static char fat_default_iocharset[] = CONFIG_FAT_DEFAULT_IOCHARSET;
38 
39 
40 static int fat_add_cluster(struct inode *inode)
41 {
42 	int err, cluster;
43 
44 	err = fat_alloc_clusters(inode, &cluster, 1);
45 	if (err)
46 		return err;
47 	/* FIXME: this cluster should be added after data of this
48 	 * cluster is writed */
49 	err = fat_chain_add(inode, cluster, 1);
50 	if (err)
51 		fat_free_clusters(inode, cluster);
52 	return err;
53 }
54 
55 static inline int __fat_get_block(struct inode *inode, sector_t iblock,
56 				  unsigned long *max_blocks,
57 				  struct buffer_head *bh_result, int create)
58 {
59 	struct super_block *sb = inode->i_sb;
60 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
61 	unsigned long mapped_blocks;
62 	sector_t phys;
63 	int err, offset;
64 
65 	err = fat_bmap(inode, iblock, &phys, &mapped_blocks);
66 	if (err)
67 		return err;
68 	if (phys) {
69 		map_bh(bh_result, sb, phys);
70 		*max_blocks = min(mapped_blocks, *max_blocks);
71 		return 0;
72 	}
73 	if (!create)
74 		return 0;
75 
76 	if (iblock != MSDOS_I(inode)->mmu_private >> sb->s_blocksize_bits) {
77 		fat_fs_panic(sb, "corrupted file size (i_pos %lld, %lld)",
78 			MSDOS_I(inode)->i_pos, MSDOS_I(inode)->mmu_private);
79 		return -EIO;
80 	}
81 
82 	offset = (unsigned long)iblock & (sbi->sec_per_clus - 1);
83 	if (!offset) {
84 		/* TODO: multiple cluster allocation would be desirable. */
85 		err = fat_add_cluster(inode);
86 		if (err)
87 			return err;
88 	}
89 	/* available blocks on this cluster */
90 	mapped_blocks = sbi->sec_per_clus - offset;
91 
92 	*max_blocks = min(mapped_blocks, *max_blocks);
93 	MSDOS_I(inode)->mmu_private += *max_blocks << sb->s_blocksize_bits;
94 
95 	err = fat_bmap(inode, iblock, &phys, &mapped_blocks);
96 	if (err)
97 		return err;
98 
99 	BUG_ON(!phys);
100 	BUG_ON(*max_blocks != mapped_blocks);
101 	set_buffer_new(bh_result);
102 	map_bh(bh_result, sb, phys);
103 
104 	return 0;
105 }
106 
107 static int fat_get_block(struct inode *inode, sector_t iblock,
108 			 struct buffer_head *bh_result, int create)
109 {
110 	struct super_block *sb = inode->i_sb;
111 	unsigned long max_blocks = bh_result->b_size >> inode->i_blkbits;
112 	int err;
113 
114 	err = __fat_get_block(inode, iblock, &max_blocks, bh_result, create);
115 	if (err)
116 		return err;
117 	bh_result->b_size = max_blocks << sb->s_blocksize_bits;
118 	return 0;
119 }
120 
121 static int fat_writepage(struct page *page, struct writeback_control *wbc)
122 {
123 	return block_write_full_page(page, fat_get_block, wbc);
124 }
125 
126 static int fat_writepages(struct address_space *mapping,
127 			  struct writeback_control *wbc)
128 {
129 	return mpage_writepages(mapping, wbc, fat_get_block);
130 }
131 
132 static int fat_readpage(struct file *file, struct page *page)
133 {
134 	return mpage_readpage(page, fat_get_block);
135 }
136 
137 static int fat_readpages(struct file *file, struct address_space *mapping,
138 			 struct list_head *pages, unsigned nr_pages)
139 {
140 	return mpage_readpages(mapping, pages, nr_pages, fat_get_block);
141 }
142 
143 static int fat_prepare_write(struct file *file, struct page *page,
144 			     unsigned from, unsigned to)
145 {
146 	return cont_prepare_write(page, from, to, fat_get_block,
147 				  &MSDOS_I(page->mapping->host)->mmu_private);
148 }
149 
150 static int fat_commit_write(struct file *file, struct page *page,
151 			    unsigned from, unsigned to)
152 {
153 	struct inode *inode = page->mapping->host;
154 	int err = generic_commit_write(file, page, from, to);
155 	if (!err && !(MSDOS_I(inode)->i_attrs & ATTR_ARCH)) {
156 		inode->i_mtime = inode->i_ctime = CURRENT_TIME_SEC;
157 		MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
158 		mark_inode_dirty(inode);
159 	}
160 	return err;
161 }
162 
163 static ssize_t fat_direct_IO(int rw, struct kiocb *iocb,
164 			     const struct iovec *iov,
165 			     loff_t offset, unsigned long nr_segs)
166 {
167 	struct file *file = iocb->ki_filp;
168 	struct inode *inode = file->f_mapping->host;
169 
170 	if (rw == WRITE) {
171 		/*
172 		 * FIXME: blockdev_direct_IO() doesn't use ->prepare_write(),
173 		 * so we need to update the ->mmu_private to block boundary.
174 		 *
175 		 * But we must fill the remaining area or hole by nul for
176 		 * updating ->mmu_private.
177 		 *
178 		 * Return 0, and fallback to normal buffered write.
179 		 */
180 		loff_t size = offset + iov_length(iov, nr_segs);
181 		if (MSDOS_I(inode)->mmu_private < size)
182 			return 0;
183 	}
184 
185 	/*
186 	 * FAT need to use the DIO_LOCKING for avoiding the race
187 	 * condition of fat_get_block() and ->truncate().
188 	 */
189 	return blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iov,
190 				  offset, nr_segs, fat_get_block, NULL);
191 }
192 
193 static sector_t _fat_bmap(struct address_space *mapping, sector_t block)
194 {
195 	return generic_block_bmap(mapping, block, fat_get_block);
196 }
197 
198 static const struct address_space_operations fat_aops = {
199 	.readpage	= fat_readpage,
200 	.readpages	= fat_readpages,
201 	.writepage	= fat_writepage,
202 	.writepages	= fat_writepages,
203 	.sync_page	= block_sync_page,
204 	.prepare_write	= fat_prepare_write,
205 	.commit_write	= fat_commit_write,
206 	.direct_IO	= fat_direct_IO,
207 	.bmap		= _fat_bmap
208 };
209 
210 /*
211  * New FAT inode stuff. We do the following:
212  *	a) i_ino is constant and has nothing with on-disk location.
213  *	b) FAT manages its own cache of directory entries.
214  *	c) *This* cache is indexed by on-disk location.
215  *	d) inode has an associated directory entry, all right, but
216  *		it may be unhashed.
217  *	e) currently entries are stored within struct inode. That should
218  *		change.
219  *	f) we deal with races in the following way:
220  *		1. readdir() and lookup() do FAT-dir-cache lookup.
221  *		2. rename() unhashes the F-d-c entry and rehashes it in
222  *			a new place.
223  *		3. unlink() and rmdir() unhash F-d-c entry.
224  *		4. fat_write_inode() checks whether the thing is unhashed.
225  *			If it is we silently return. If it isn't we do bread(),
226  *			check if the location is still valid and retry if it
227  *			isn't. Otherwise we do changes.
228  *		5. Spinlock is used to protect hash/unhash/location check/lookup
229  *		6. fat_clear_inode() unhashes the F-d-c entry.
230  *		7. lookup() and readdir() do igrab() if they find a F-d-c entry
231  *			and consider negative result as cache miss.
232  */
233 
234 static void fat_hash_init(struct super_block *sb)
235 {
236 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
237 	int i;
238 
239 	spin_lock_init(&sbi->inode_hash_lock);
240 	for (i = 0; i < FAT_HASH_SIZE; i++)
241 		INIT_HLIST_HEAD(&sbi->inode_hashtable[i]);
242 }
243 
244 static inline unsigned long fat_hash(struct super_block *sb, loff_t i_pos)
245 {
246 	unsigned long tmp = (unsigned long)i_pos | (unsigned long) sb;
247 	tmp = tmp + (tmp >> FAT_HASH_BITS) + (tmp >> FAT_HASH_BITS * 2);
248 	return tmp & FAT_HASH_MASK;
249 }
250 
251 void fat_attach(struct inode *inode, loff_t i_pos)
252 {
253 	struct super_block *sb = inode->i_sb;
254 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
255 
256 	spin_lock(&sbi->inode_hash_lock);
257 	MSDOS_I(inode)->i_pos = i_pos;
258 	hlist_add_head(&MSDOS_I(inode)->i_fat_hash,
259 			sbi->inode_hashtable + fat_hash(sb, i_pos));
260 	spin_unlock(&sbi->inode_hash_lock);
261 }
262 
263 EXPORT_SYMBOL_GPL(fat_attach);
264 
265 void fat_detach(struct inode *inode)
266 {
267 	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
268 	spin_lock(&sbi->inode_hash_lock);
269 	MSDOS_I(inode)->i_pos = 0;
270 	hlist_del_init(&MSDOS_I(inode)->i_fat_hash);
271 	spin_unlock(&sbi->inode_hash_lock);
272 }
273 
274 EXPORT_SYMBOL_GPL(fat_detach);
275 
276 struct inode *fat_iget(struct super_block *sb, loff_t i_pos)
277 {
278 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
279 	struct hlist_head *head = sbi->inode_hashtable + fat_hash(sb, i_pos);
280 	struct hlist_node *_p;
281 	struct msdos_inode_info *i;
282 	struct inode *inode = NULL;
283 
284 	spin_lock(&sbi->inode_hash_lock);
285 	hlist_for_each_entry(i, _p, head, i_fat_hash) {
286 		BUG_ON(i->vfs_inode.i_sb != sb);
287 		if (i->i_pos != i_pos)
288 			continue;
289 		inode = igrab(&i->vfs_inode);
290 		if (inode)
291 			break;
292 	}
293 	spin_unlock(&sbi->inode_hash_lock);
294 	return inode;
295 }
296 
297 static int is_exec(unsigned char *extension)
298 {
299 	unsigned char *exe_extensions = "EXECOMBAT", *walk;
300 
301 	for (walk = exe_extensions; *walk; walk += 3)
302 		if (!strncmp(extension, walk, 3))
303 			return 1;
304 	return 0;
305 }
306 
307 static int fat_calc_dir_size(struct inode *inode)
308 {
309 	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
310 	int ret, fclus, dclus;
311 
312 	inode->i_size = 0;
313 	if (MSDOS_I(inode)->i_start == 0)
314 		return 0;
315 
316 	ret = fat_get_cluster(inode, FAT_ENT_EOF, &fclus, &dclus);
317 	if (ret < 0)
318 		return ret;
319 	inode->i_size = (fclus + 1) << sbi->cluster_bits;
320 
321 	return 0;
322 }
323 
324 /* doesn't deal with root inode */
325 static int fat_fill_inode(struct inode *inode, struct msdos_dir_entry *de)
326 {
327 	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
328 	int error;
329 
330 	MSDOS_I(inode)->i_pos = 0;
331 	inode->i_uid = sbi->options.fs_uid;
332 	inode->i_gid = sbi->options.fs_gid;
333 	inode->i_version++;
334 	inode->i_generation = get_seconds();
335 
336 	if ((de->attr & ATTR_DIR) && !IS_FREE(de->name)) {
337 		inode->i_generation &= ~1;
338 		inode->i_mode = MSDOS_MKMODE(de->attr,
339 			S_IRWXUGO & ~sbi->options.fs_dmask) | S_IFDIR;
340 		inode->i_op = sbi->dir_ops;
341 		inode->i_fop = &fat_dir_operations;
342 
343 		MSDOS_I(inode)->i_start = le16_to_cpu(de->start);
344 		if (sbi->fat_bits == 32)
345 			MSDOS_I(inode)->i_start |= (le16_to_cpu(de->starthi) << 16);
346 
347 		MSDOS_I(inode)->i_logstart = MSDOS_I(inode)->i_start;
348 		error = fat_calc_dir_size(inode);
349 		if (error < 0)
350 			return error;
351 		MSDOS_I(inode)->mmu_private = inode->i_size;
352 
353 		inode->i_nlink = fat_subdirs(inode);
354 	} else { /* not a directory */
355 		inode->i_generation |= 1;
356 		inode->i_mode = MSDOS_MKMODE(de->attr,
357 		    ((sbi->options.showexec &&
358 			!is_exec(de->ext))
359 			? S_IRUGO|S_IWUGO : S_IRWXUGO)
360 		    & ~sbi->options.fs_fmask) | S_IFREG;
361 		MSDOS_I(inode)->i_start = le16_to_cpu(de->start);
362 		if (sbi->fat_bits == 32)
363 			MSDOS_I(inode)->i_start |= (le16_to_cpu(de->starthi) << 16);
364 
365 		MSDOS_I(inode)->i_logstart = MSDOS_I(inode)->i_start;
366 		inode->i_size = le32_to_cpu(de->size);
367 		inode->i_op = &fat_file_inode_operations;
368 		inode->i_fop = &fat_file_operations;
369 		inode->i_mapping->a_ops = &fat_aops;
370 		MSDOS_I(inode)->mmu_private = inode->i_size;
371 	}
372 	if (de->attr & ATTR_SYS) {
373 		if (sbi->options.sys_immutable)
374 			inode->i_flags |= S_IMMUTABLE;
375 	}
376 	MSDOS_I(inode)->i_attrs = de->attr & ATTR_UNUSED;
377 	inode->i_blocks = ((inode->i_size + (sbi->cluster_size - 1))
378 			   & ~((loff_t)sbi->cluster_size - 1)) >> 9;
379 	inode->i_mtime.tv_sec =
380 		date_dos2unix(le16_to_cpu(de->time), le16_to_cpu(de->date));
381 	inode->i_mtime.tv_nsec = 0;
382 	if (sbi->options.isvfat) {
383 		int secs = de->ctime_cs / 100;
384 		int csecs = de->ctime_cs % 100;
385 		inode->i_ctime.tv_sec  =
386 			date_dos2unix(le16_to_cpu(de->ctime),
387 				      le16_to_cpu(de->cdate)) + secs;
388 		inode->i_ctime.tv_nsec = csecs * 10000000;
389 		inode->i_atime.tv_sec =
390 			date_dos2unix(0, le16_to_cpu(de->adate));
391 		inode->i_atime.tv_nsec = 0;
392 	} else
393 		inode->i_ctime = inode->i_atime = inode->i_mtime;
394 
395 	return 0;
396 }
397 
398 struct inode *fat_build_inode(struct super_block *sb,
399 			struct msdos_dir_entry *de, loff_t i_pos)
400 {
401 	struct inode *inode;
402 	int err;
403 
404 	inode = fat_iget(sb, i_pos);
405 	if (inode)
406 		goto out;
407 	inode = new_inode(sb);
408 	if (!inode) {
409 		inode = ERR_PTR(-ENOMEM);
410 		goto out;
411 	}
412 	inode->i_ino = iunique(sb, MSDOS_ROOT_INO);
413 	inode->i_version = 1;
414 	err = fat_fill_inode(inode, de);
415 	if (err) {
416 		iput(inode);
417 		inode = ERR_PTR(err);
418 		goto out;
419 	}
420 	fat_attach(inode, i_pos);
421 	insert_inode_hash(inode);
422 out:
423 	return inode;
424 }
425 
426 EXPORT_SYMBOL_GPL(fat_build_inode);
427 
428 static void fat_delete_inode(struct inode *inode)
429 {
430 	truncate_inode_pages(&inode->i_data, 0);
431 
432 	if (!is_bad_inode(inode)) {
433 		inode->i_size = 0;
434 		fat_truncate(inode);
435 	}
436 	clear_inode(inode);
437 }
438 
439 static void fat_clear_inode(struct inode *inode)
440 {
441 	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
442 
443 	if (is_bad_inode(inode))
444 		return;
445 	lock_kernel();
446 	spin_lock(&sbi->inode_hash_lock);
447 	fat_cache_inval_inode(inode);
448 	hlist_del_init(&MSDOS_I(inode)->i_fat_hash);
449 	spin_unlock(&sbi->inode_hash_lock);
450 	unlock_kernel();
451 }
452 
453 static void fat_write_super(struct super_block *sb)
454 {
455 	sb->s_dirt = 0;
456 
457 	if (!(sb->s_flags & MS_RDONLY))
458 		fat_clusters_flush(sb);
459 }
460 
461 static void fat_put_super(struct super_block *sb)
462 {
463 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
464 
465 	if (sbi->nls_disk) {
466 		unload_nls(sbi->nls_disk);
467 		sbi->nls_disk = NULL;
468 		sbi->options.codepage = fat_default_codepage;
469 	}
470 	if (sbi->nls_io) {
471 		unload_nls(sbi->nls_io);
472 		sbi->nls_io = NULL;
473 	}
474 	if (sbi->options.iocharset != fat_default_iocharset) {
475 		kfree(sbi->options.iocharset);
476 		sbi->options.iocharset = fat_default_iocharset;
477 	}
478 
479 	sb->s_fs_info = NULL;
480 	kfree(sbi);
481 }
482 
483 static struct kmem_cache *fat_inode_cachep;
484 
485 static struct inode *fat_alloc_inode(struct super_block *sb)
486 {
487 	struct msdos_inode_info *ei;
488 	ei = kmem_cache_alloc(fat_inode_cachep, GFP_KERNEL);
489 	if (!ei)
490 		return NULL;
491 	return &ei->vfs_inode;
492 }
493 
494 static void fat_destroy_inode(struct inode *inode)
495 {
496 	kmem_cache_free(fat_inode_cachep, MSDOS_I(inode));
497 }
498 
499 static void init_once(void * foo, struct kmem_cache * cachep, unsigned long flags)
500 {
501 	struct msdos_inode_info *ei = (struct msdos_inode_info *)foo;
502 
503 	if (flags & SLAB_CTOR_CONSTRUCTOR) {
504 		spin_lock_init(&ei->cache_lru_lock);
505 		ei->nr_caches = 0;
506 		ei->cache_valid_id = FAT_CACHE_VALID + 1;
507 		INIT_LIST_HEAD(&ei->cache_lru);
508 		INIT_HLIST_NODE(&ei->i_fat_hash);
509 		inode_init_once(&ei->vfs_inode);
510 	}
511 }
512 
513 static int __init fat_init_inodecache(void)
514 {
515 	fat_inode_cachep = kmem_cache_create("fat_inode_cache",
516 					     sizeof(struct msdos_inode_info),
517 					     0, (SLAB_RECLAIM_ACCOUNT|
518 						SLAB_MEM_SPREAD),
519 					     init_once, NULL);
520 	if (fat_inode_cachep == NULL)
521 		return -ENOMEM;
522 	return 0;
523 }
524 
525 static void __exit fat_destroy_inodecache(void)
526 {
527 	kmem_cache_destroy(fat_inode_cachep);
528 }
529 
530 static int fat_remount(struct super_block *sb, int *flags, char *data)
531 {
532 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
533 	*flags |= MS_NODIRATIME | (sbi->options.isvfat ? 0 : MS_NOATIME);
534 	return 0;
535 }
536 
537 static int fat_statfs(struct dentry *dentry, struct kstatfs *buf)
538 {
539 	struct msdos_sb_info *sbi = MSDOS_SB(dentry->d_sb);
540 
541 	/* If the count of free cluster is still unknown, counts it here. */
542 	if (sbi->free_clusters == -1) {
543 		int err = fat_count_free_clusters(dentry->d_sb);
544 		if (err)
545 			return err;
546 	}
547 
548 	buf->f_type = dentry->d_sb->s_magic;
549 	buf->f_bsize = sbi->cluster_size;
550 	buf->f_blocks = sbi->max_cluster - FAT_START_ENT;
551 	buf->f_bfree = sbi->free_clusters;
552 	buf->f_bavail = sbi->free_clusters;
553 	buf->f_namelen = sbi->options.isvfat ? 260 : 12;
554 
555 	return 0;
556 }
557 
558 static int fat_write_inode(struct inode *inode, int wait)
559 {
560 	struct super_block *sb = inode->i_sb;
561 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
562 	struct buffer_head *bh;
563 	struct msdos_dir_entry *raw_entry;
564 	loff_t i_pos;
565 	int err = 0;
566 
567 retry:
568 	i_pos = MSDOS_I(inode)->i_pos;
569 	if (inode->i_ino == MSDOS_ROOT_INO || !i_pos)
570 		return 0;
571 
572 	lock_kernel();
573 	bh = sb_bread(sb, i_pos >> sbi->dir_per_block_bits);
574 	if (!bh) {
575 		printk(KERN_ERR "FAT: unable to read inode block "
576 		       "for updating (i_pos %lld)\n", i_pos);
577 		err = -EIO;
578 		goto out;
579 	}
580 	spin_lock(&sbi->inode_hash_lock);
581 	if (i_pos != MSDOS_I(inode)->i_pos) {
582 		spin_unlock(&sbi->inode_hash_lock);
583 		brelse(bh);
584 		unlock_kernel();
585 		goto retry;
586 	}
587 
588 	raw_entry = &((struct msdos_dir_entry *) (bh->b_data))
589 	    [i_pos & (sbi->dir_per_block - 1)];
590 	if (S_ISDIR(inode->i_mode))
591 		raw_entry->size = 0;
592 	else
593 		raw_entry->size = cpu_to_le32(inode->i_size);
594 	raw_entry->attr = fat_attr(inode);
595 	raw_entry->start = cpu_to_le16(MSDOS_I(inode)->i_logstart);
596 	raw_entry->starthi = cpu_to_le16(MSDOS_I(inode)->i_logstart >> 16);
597 	fat_date_unix2dos(inode->i_mtime.tv_sec, &raw_entry->time, &raw_entry->date);
598 	if (sbi->options.isvfat) {
599 		__le16 atime;
600 		fat_date_unix2dos(inode->i_ctime.tv_sec,&raw_entry->ctime,&raw_entry->cdate);
601 		fat_date_unix2dos(inode->i_atime.tv_sec,&atime,&raw_entry->adate);
602 		raw_entry->ctime_cs = (inode->i_ctime.tv_sec & 1) * 100 +
603 			inode->i_ctime.tv_nsec / 10000000;
604 	}
605 	spin_unlock(&sbi->inode_hash_lock);
606 	mark_buffer_dirty(bh);
607 	if (wait)
608 		err = sync_dirty_buffer(bh);
609 	brelse(bh);
610 out:
611 	unlock_kernel();
612 	return err;
613 }
614 
615 int fat_sync_inode(struct inode *inode)
616 {
617 	return fat_write_inode(inode, 1);
618 }
619 
620 EXPORT_SYMBOL_GPL(fat_sync_inode);
621 
622 static int fat_show_options(struct seq_file *m, struct vfsmount *mnt);
623 static const struct super_operations fat_sops = {
624 	.alloc_inode	= fat_alloc_inode,
625 	.destroy_inode	= fat_destroy_inode,
626 	.write_inode	= fat_write_inode,
627 	.delete_inode	= fat_delete_inode,
628 	.put_super	= fat_put_super,
629 	.write_super	= fat_write_super,
630 	.statfs		= fat_statfs,
631 	.clear_inode	= fat_clear_inode,
632 	.remount_fs	= fat_remount,
633 
634 	.read_inode	= make_bad_inode,
635 
636 	.show_options	= fat_show_options,
637 };
638 
639 /*
640  * a FAT file handle with fhtype 3 is
641  *  0/  i_ino - for fast, reliable lookup if still in the cache
642  *  1/  i_generation - to see if i_ino is still valid
643  *          bit 0 == 0 iff directory
644  *  2/  i_pos(8-39) - if ino has changed, but still in cache
645  *  3/  i_pos(4-7)|i_logstart - to semi-verify inode found at i_pos
646  *  4/  i_pos(0-3)|parent->i_logstart - maybe used to hunt for the file on disc
647  *
648  * Hack for NFSv2: Maximum FAT entry number is 28bits and maximum
649  * i_pos is 40bits (blocknr(32) + dir offset(8)), so two 4bits
650  * of i_logstart is used to store the directory entry offset.
651  */
652 
653 static struct dentry *
654 fat_decode_fh(struct super_block *sb, __u32 *fh, int len, int fhtype,
655 	      int (*acceptable)(void *context, struct dentry *de),
656 	      void *context)
657 {
658 	if (fhtype != 3)
659 		return ERR_PTR(-ESTALE);
660 	if (len < 5)
661 		return ERR_PTR(-ESTALE);
662 
663 	return sb->s_export_op->find_exported_dentry(sb, fh, NULL, acceptable, context);
664 }
665 
666 static struct dentry *fat_get_dentry(struct super_block *sb, void *inump)
667 {
668 	struct inode *inode = NULL;
669 	struct dentry *result;
670 	__u32 *fh = inump;
671 
672 	inode = iget(sb, fh[0]);
673 	if (!inode || is_bad_inode(inode) || inode->i_generation != fh[1]) {
674 		if (inode)
675 			iput(inode);
676 		inode = NULL;
677 	}
678 	if (!inode) {
679 		loff_t i_pos;
680 		int i_logstart = fh[3] & 0x0fffffff;
681 
682 		i_pos = (loff_t)fh[2] << 8;
683 		i_pos |= ((fh[3] >> 24) & 0xf0) | (fh[4] >> 28);
684 
685 		/* try 2 - see if i_pos is in F-d-c
686 		 * require i_logstart to be the same
687 		 * Will fail if you truncate and then re-write
688 		 */
689 
690 		inode = fat_iget(sb, i_pos);
691 		if (inode && MSDOS_I(inode)->i_logstart != i_logstart) {
692 			iput(inode);
693 			inode = NULL;
694 		}
695 	}
696 	if (!inode) {
697 		/* For now, do nothing
698 		 * What we could do is:
699 		 * follow the file starting at fh[4], and record
700 		 * the ".." entry, and the name of the fh[2] entry.
701 		 * The follow the ".." file finding the next step up.
702 		 * This way we build a path to the root of
703 		 * the tree. If this works, we lookup the path and so
704 		 * get this inode into the cache.
705 		 * Finally try the fat_iget lookup again
706 		 * If that fails, then weare totally out of luck
707 		 * But all that is for another day
708 		 */
709 	}
710 	if (!inode)
711 		return ERR_PTR(-ESTALE);
712 
713 
714 	/* now to find a dentry.
715 	 * If possible, get a well-connected one
716 	 */
717 	result = d_alloc_anon(inode);
718 	if (result == NULL) {
719 		iput(inode);
720 		return ERR_PTR(-ENOMEM);
721 	}
722 	result->d_op = sb->s_root->d_op;
723 	return result;
724 }
725 
726 static int
727 fat_encode_fh(struct dentry *de, __u32 *fh, int *lenp, int connectable)
728 {
729 	int len = *lenp;
730 	struct inode *inode =  de->d_inode;
731 	u32 ipos_h, ipos_m, ipos_l;
732 
733 	if (len < 5)
734 		return 255; /* no room */
735 
736 	ipos_h = MSDOS_I(inode)->i_pos >> 8;
737 	ipos_m = (MSDOS_I(inode)->i_pos & 0xf0) << 24;
738 	ipos_l = (MSDOS_I(inode)->i_pos & 0x0f) << 28;
739 	*lenp = 5;
740 	fh[0] = inode->i_ino;
741 	fh[1] = inode->i_generation;
742 	fh[2] = ipos_h;
743 	fh[3] = ipos_m | MSDOS_I(inode)->i_logstart;
744 	spin_lock(&de->d_lock);
745 	fh[4] = ipos_l | MSDOS_I(de->d_parent->d_inode)->i_logstart;
746 	spin_unlock(&de->d_lock);
747 	return 3;
748 }
749 
750 static struct dentry *fat_get_parent(struct dentry *child)
751 {
752 	struct buffer_head *bh;
753 	struct msdos_dir_entry *de;
754 	loff_t i_pos;
755 	struct dentry *parent;
756 	struct inode *inode;
757 	int err;
758 
759 	lock_kernel();
760 
761 	err = fat_get_dotdot_entry(child->d_inode, &bh, &de, &i_pos);
762 	if (err) {
763 		parent = ERR_PTR(err);
764 		goto out;
765 	}
766 	inode = fat_build_inode(child->d_sb, de, i_pos);
767 	brelse(bh);
768 	if (IS_ERR(inode)) {
769 		parent = ERR_PTR(PTR_ERR(inode));
770 		goto out;
771 	}
772 	parent = d_alloc_anon(inode);
773 	if (!parent) {
774 		iput(inode);
775 		parent = ERR_PTR(-ENOMEM);
776 	}
777 out:
778 	unlock_kernel();
779 
780 	return parent;
781 }
782 
783 static struct export_operations fat_export_ops = {
784 	.decode_fh	= fat_decode_fh,
785 	.encode_fh	= fat_encode_fh,
786 	.get_dentry	= fat_get_dentry,
787 	.get_parent	= fat_get_parent,
788 };
789 
790 static int fat_show_options(struct seq_file *m, struct vfsmount *mnt)
791 {
792 	struct msdos_sb_info *sbi = MSDOS_SB(mnt->mnt_sb);
793 	struct fat_mount_options *opts = &sbi->options;
794 	int isvfat = opts->isvfat;
795 
796 	if (opts->fs_uid != 0)
797 		seq_printf(m, ",uid=%u", opts->fs_uid);
798 	if (opts->fs_gid != 0)
799 		seq_printf(m, ",gid=%u", opts->fs_gid);
800 	seq_printf(m, ",fmask=%04o", opts->fs_fmask);
801 	seq_printf(m, ",dmask=%04o", opts->fs_dmask);
802 	if (sbi->nls_disk)
803 		seq_printf(m, ",codepage=%s", sbi->nls_disk->charset);
804 	if (isvfat) {
805 		if (sbi->nls_io)
806 			seq_printf(m, ",iocharset=%s", sbi->nls_io->charset);
807 
808 		switch (opts->shortname) {
809 		case VFAT_SFN_DISPLAY_WIN95 | VFAT_SFN_CREATE_WIN95:
810 			seq_puts(m, ",shortname=win95");
811 			break;
812 		case VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WINNT:
813 			seq_puts(m, ",shortname=winnt");
814 			break;
815 		case VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WIN95:
816 			seq_puts(m, ",shortname=mixed");
817 			break;
818 		case VFAT_SFN_DISPLAY_LOWER | VFAT_SFN_CREATE_WIN95:
819 			/* seq_puts(m, ",shortname=lower"); */
820 			break;
821 		default:
822 			seq_puts(m, ",shortname=unknown");
823 			break;
824 		}
825 	}
826 	if (opts->name_check != 'n')
827 		seq_printf(m, ",check=%c", opts->name_check);
828 	if (opts->usefree)
829 		seq_puts(m, ",usefree");
830 	if (opts->quiet)
831 		seq_puts(m, ",quiet");
832 	if (opts->showexec)
833 		seq_puts(m, ",showexec");
834 	if (opts->sys_immutable)
835 		seq_puts(m, ",sys_immutable");
836 	if (!isvfat) {
837 		if (opts->dotsOK)
838 			seq_puts(m, ",dotsOK=yes");
839 		if (opts->nocase)
840 			seq_puts(m, ",nocase");
841 	} else {
842 		if (opts->utf8)
843 			seq_puts(m, ",utf8");
844 		if (opts->unicode_xlate)
845 			seq_puts(m, ",uni_xlate");
846 		if (!opts->numtail)
847 			seq_puts(m, ",nonumtail");
848 	}
849 
850 	return 0;
851 }
852 
853 enum {
854 	Opt_check_n, Opt_check_r, Opt_check_s, Opt_uid, Opt_gid,
855 	Opt_umask, Opt_dmask, Opt_fmask, Opt_codepage, Opt_usefree, Opt_nocase,
856 	Opt_quiet, Opt_showexec, Opt_debug, Opt_immutable,
857 	Opt_dots, Opt_nodots,
858 	Opt_charset, Opt_shortname_lower, Opt_shortname_win95,
859 	Opt_shortname_winnt, Opt_shortname_mixed, Opt_utf8_no, Opt_utf8_yes,
860 	Opt_uni_xl_no, Opt_uni_xl_yes, Opt_nonumtail_no, Opt_nonumtail_yes,
861 	Opt_obsolate, Opt_flush, Opt_err,
862 };
863 
864 static match_table_t fat_tokens = {
865 	{Opt_check_r, "check=relaxed"},
866 	{Opt_check_s, "check=strict"},
867 	{Opt_check_n, "check=normal"},
868 	{Opt_check_r, "check=r"},
869 	{Opt_check_s, "check=s"},
870 	{Opt_check_n, "check=n"},
871 	{Opt_uid, "uid=%u"},
872 	{Opt_gid, "gid=%u"},
873 	{Opt_umask, "umask=%o"},
874 	{Opt_dmask, "dmask=%o"},
875 	{Opt_fmask, "fmask=%o"},
876 	{Opt_codepage, "codepage=%u"},
877 	{Opt_usefree, "usefree"},
878 	{Opt_nocase, "nocase"},
879 	{Opt_quiet, "quiet"},
880 	{Opt_showexec, "showexec"},
881 	{Opt_debug, "debug"},
882 	{Opt_immutable, "sys_immutable"},
883 	{Opt_obsolate, "conv=binary"},
884 	{Opt_obsolate, "conv=text"},
885 	{Opt_obsolate, "conv=auto"},
886 	{Opt_obsolate, "conv=b"},
887 	{Opt_obsolate, "conv=t"},
888 	{Opt_obsolate, "conv=a"},
889 	{Opt_obsolate, "fat=%u"},
890 	{Opt_obsolate, "blocksize=%u"},
891 	{Opt_obsolate, "cvf_format=%20s"},
892 	{Opt_obsolate, "cvf_options=%100s"},
893 	{Opt_obsolate, "posix"},
894 	{Opt_flush, "flush"},
895 	{Opt_err, NULL},
896 };
897 static match_table_t msdos_tokens = {
898 	{Opt_nodots, "nodots"},
899 	{Opt_nodots, "dotsOK=no"},
900 	{Opt_dots, "dots"},
901 	{Opt_dots, "dotsOK=yes"},
902 	{Opt_err, NULL}
903 };
904 static match_table_t vfat_tokens = {
905 	{Opt_charset, "iocharset=%s"},
906 	{Opt_shortname_lower, "shortname=lower"},
907 	{Opt_shortname_win95, "shortname=win95"},
908 	{Opt_shortname_winnt, "shortname=winnt"},
909 	{Opt_shortname_mixed, "shortname=mixed"},
910 	{Opt_utf8_no, "utf8=0"},		/* 0 or no or false */
911 	{Opt_utf8_no, "utf8=no"},
912 	{Opt_utf8_no, "utf8=false"},
913 	{Opt_utf8_yes, "utf8=1"},		/* empty or 1 or yes or true */
914 	{Opt_utf8_yes, "utf8=yes"},
915 	{Opt_utf8_yes, "utf8=true"},
916 	{Opt_utf8_yes, "utf8"},
917 	{Opt_uni_xl_no, "uni_xlate=0"},		/* 0 or no or false */
918 	{Opt_uni_xl_no, "uni_xlate=no"},
919 	{Opt_uni_xl_no, "uni_xlate=false"},
920 	{Opt_uni_xl_yes, "uni_xlate=1"},	/* empty or 1 or yes or true */
921 	{Opt_uni_xl_yes, "uni_xlate=yes"},
922 	{Opt_uni_xl_yes, "uni_xlate=true"},
923 	{Opt_uni_xl_yes, "uni_xlate"},
924 	{Opt_nonumtail_no, "nonumtail=0"},	/* 0 or no or false */
925 	{Opt_nonumtail_no, "nonumtail=no"},
926 	{Opt_nonumtail_no, "nonumtail=false"},
927 	{Opt_nonumtail_yes, "nonumtail=1"},	/* empty or 1 or yes or true */
928 	{Opt_nonumtail_yes, "nonumtail=yes"},
929 	{Opt_nonumtail_yes, "nonumtail=true"},
930 	{Opt_nonumtail_yes, "nonumtail"},
931 	{Opt_err, NULL}
932 };
933 
934 static int parse_options(char *options, int is_vfat, int silent, int *debug,
935 			 struct fat_mount_options *opts)
936 {
937 	char *p;
938 	substring_t args[MAX_OPT_ARGS];
939 	int option;
940 	char *iocharset;
941 
942 	opts->isvfat = is_vfat;
943 
944 	opts->fs_uid = current->uid;
945 	opts->fs_gid = current->gid;
946 	opts->fs_fmask = opts->fs_dmask = current->fs->umask;
947 	opts->codepage = fat_default_codepage;
948 	opts->iocharset = fat_default_iocharset;
949 	if (is_vfat)
950 		opts->shortname = VFAT_SFN_DISPLAY_LOWER|VFAT_SFN_CREATE_WIN95;
951 	else
952 		opts->shortname = 0;
953 	opts->name_check = 'n';
954 	opts->quiet = opts->showexec = opts->sys_immutable = opts->dotsOK =  0;
955 	opts->utf8 = opts->unicode_xlate = 0;
956 	opts->numtail = 1;
957 	opts->usefree = opts->nocase = 0;
958 	*debug = 0;
959 
960 	if (!options)
961 		return 0;
962 
963 	while ((p = strsep(&options, ",")) != NULL) {
964 		int token;
965 		if (!*p)
966 			continue;
967 
968 		token = match_token(p, fat_tokens, args);
969 		if (token == Opt_err) {
970 			if (is_vfat)
971 				token = match_token(p, vfat_tokens, args);
972 			else
973 				token = match_token(p, msdos_tokens, args);
974 		}
975 		switch (token) {
976 		case Opt_check_s:
977 			opts->name_check = 's';
978 			break;
979 		case Opt_check_r:
980 			opts->name_check = 'r';
981 			break;
982 		case Opt_check_n:
983 			opts->name_check = 'n';
984 			break;
985 		case Opt_usefree:
986 			opts->usefree = 1;
987 			break;
988 		case Opt_nocase:
989 			if (!is_vfat)
990 				opts->nocase = 1;
991 			else {
992 				/* for backward compatibility */
993 				opts->shortname = VFAT_SFN_DISPLAY_WIN95
994 					| VFAT_SFN_CREATE_WIN95;
995 			}
996 			break;
997 		case Opt_quiet:
998 			opts->quiet = 1;
999 			break;
1000 		case Opt_showexec:
1001 			opts->showexec = 1;
1002 			break;
1003 		case Opt_debug:
1004 			*debug = 1;
1005 			break;
1006 		case Opt_immutable:
1007 			opts->sys_immutable = 1;
1008 			break;
1009 		case Opt_uid:
1010 			if (match_int(&args[0], &option))
1011 				return 0;
1012 			opts->fs_uid = option;
1013 			break;
1014 		case Opt_gid:
1015 			if (match_int(&args[0], &option))
1016 				return 0;
1017 			opts->fs_gid = option;
1018 			break;
1019 		case Opt_umask:
1020 			if (match_octal(&args[0], &option))
1021 				return 0;
1022 			opts->fs_fmask = opts->fs_dmask = option;
1023 			break;
1024 		case Opt_dmask:
1025 			if (match_octal(&args[0], &option))
1026 				return 0;
1027 			opts->fs_dmask = option;
1028 			break;
1029 		case Opt_fmask:
1030 			if (match_octal(&args[0], &option))
1031 				return 0;
1032 			opts->fs_fmask = option;
1033 			break;
1034 		case Opt_codepage:
1035 			if (match_int(&args[0], &option))
1036 				return 0;
1037 			opts->codepage = option;
1038 			break;
1039 		case Opt_flush:
1040 			opts->flush = 1;
1041 			break;
1042 
1043 		/* msdos specific */
1044 		case Opt_dots:
1045 			opts->dotsOK = 1;
1046 			break;
1047 		case Opt_nodots:
1048 			opts->dotsOK = 0;
1049 			break;
1050 
1051 		/* vfat specific */
1052 		case Opt_charset:
1053 			if (opts->iocharset != fat_default_iocharset)
1054 				kfree(opts->iocharset);
1055 			iocharset = match_strdup(&args[0]);
1056 			if (!iocharset)
1057 				return -ENOMEM;
1058 			opts->iocharset = iocharset;
1059 			break;
1060 		case Opt_shortname_lower:
1061 			opts->shortname = VFAT_SFN_DISPLAY_LOWER
1062 					| VFAT_SFN_CREATE_WIN95;
1063 			break;
1064 		case Opt_shortname_win95:
1065 			opts->shortname = VFAT_SFN_DISPLAY_WIN95
1066 					| VFAT_SFN_CREATE_WIN95;
1067 			break;
1068 		case Opt_shortname_winnt:
1069 			opts->shortname = VFAT_SFN_DISPLAY_WINNT
1070 					| VFAT_SFN_CREATE_WINNT;
1071 			break;
1072 		case Opt_shortname_mixed:
1073 			opts->shortname = VFAT_SFN_DISPLAY_WINNT
1074 					| VFAT_SFN_CREATE_WIN95;
1075 			break;
1076 		case Opt_utf8_no:		/* 0 or no or false */
1077 			opts->utf8 = 0;
1078 			break;
1079 		case Opt_utf8_yes:		/* empty or 1 or yes or true */
1080 			opts->utf8 = 1;
1081 			break;
1082 		case Opt_uni_xl_no:		/* 0 or no or false */
1083 			opts->unicode_xlate = 0;
1084 			break;
1085 		case Opt_uni_xl_yes:		/* empty or 1 or yes or true */
1086 			opts->unicode_xlate = 1;
1087 			break;
1088 		case Opt_nonumtail_no:		/* 0 or no or false */
1089 			opts->numtail = 1;	/* negated option */
1090 			break;
1091 		case Opt_nonumtail_yes:		/* empty or 1 or yes or true */
1092 			opts->numtail = 0;	/* negated option */
1093 			break;
1094 
1095 		/* obsolete mount options */
1096 		case Opt_obsolate:
1097 			printk(KERN_INFO "FAT: \"%s\" option is obsolete, "
1098 			       "not supported now\n", p);
1099 			break;
1100 		/* unknown option */
1101 		default:
1102 			if (!silent) {
1103 				printk(KERN_ERR
1104 				       "FAT: Unrecognized mount option \"%s\" "
1105 				       "or missing value\n", p);
1106 			}
1107 			return -EINVAL;
1108 		}
1109 	}
1110 	/* UTF-8 doesn't provide FAT semantics */
1111 	if (!strcmp(opts->iocharset, "utf8")) {
1112 		printk(KERN_ERR "FAT: utf8 is not a recommended IO charset"
1113 		       " for FAT filesystems, filesystem will be case sensitive!\n");
1114 	}
1115 
1116 	if (opts->unicode_xlate)
1117 		opts->utf8 = 0;
1118 
1119 	return 0;
1120 }
1121 
1122 static int fat_read_root(struct inode *inode)
1123 {
1124 	struct super_block *sb = inode->i_sb;
1125 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
1126 	int error;
1127 
1128 	MSDOS_I(inode)->i_pos = 0;
1129 	inode->i_uid = sbi->options.fs_uid;
1130 	inode->i_gid = sbi->options.fs_gid;
1131 	inode->i_version++;
1132 	inode->i_generation = 0;
1133 	inode->i_mode = (S_IRWXUGO & ~sbi->options.fs_dmask) | S_IFDIR;
1134 	inode->i_op = sbi->dir_ops;
1135 	inode->i_fop = &fat_dir_operations;
1136 	if (sbi->fat_bits == 32) {
1137 		MSDOS_I(inode)->i_start = sbi->root_cluster;
1138 		error = fat_calc_dir_size(inode);
1139 		if (error < 0)
1140 			return error;
1141 	} else {
1142 		MSDOS_I(inode)->i_start = 0;
1143 		inode->i_size = sbi->dir_entries * sizeof(struct msdos_dir_entry);
1144 	}
1145 	inode->i_blocks = ((inode->i_size + (sbi->cluster_size - 1))
1146 			   & ~((loff_t)sbi->cluster_size - 1)) >> 9;
1147 	MSDOS_I(inode)->i_logstart = 0;
1148 	MSDOS_I(inode)->mmu_private = inode->i_size;
1149 
1150 	MSDOS_I(inode)->i_attrs = ATTR_NONE;
1151 	inode->i_mtime.tv_sec = inode->i_atime.tv_sec = inode->i_ctime.tv_sec = 0;
1152 	inode->i_mtime.tv_nsec = inode->i_atime.tv_nsec = inode->i_ctime.tv_nsec = 0;
1153 	inode->i_nlink = fat_subdirs(inode)+2;
1154 
1155 	return 0;
1156 }
1157 
1158 /*
1159  * Read the super block of an MS-DOS FS.
1160  */
1161 int fat_fill_super(struct super_block *sb, void *data, int silent,
1162 		   const struct inode_operations *fs_dir_inode_ops, int isvfat)
1163 {
1164 	struct inode *root_inode = NULL;
1165 	struct buffer_head *bh;
1166 	struct fat_boot_sector *b;
1167 	struct msdos_sb_info *sbi;
1168 	u16 logical_sector_size;
1169 	u32 total_sectors, total_clusters, fat_clusters, rootdir_sectors;
1170 	int debug;
1171 	unsigned int media;
1172 	long error;
1173 	char buf[50];
1174 
1175 	sbi = kzalloc(sizeof(struct msdos_sb_info), GFP_KERNEL);
1176 	if (!sbi)
1177 		return -ENOMEM;
1178 	sb->s_fs_info = sbi;
1179 
1180 	sb->s_flags |= MS_NODIRATIME;
1181 	sb->s_magic = MSDOS_SUPER_MAGIC;
1182 	sb->s_op = &fat_sops;
1183 	sb->s_export_op = &fat_export_ops;
1184 	sbi->dir_ops = fs_dir_inode_ops;
1185 
1186 	error = parse_options(data, isvfat, silent, &debug, &sbi->options);
1187 	if (error)
1188 		goto out_fail;
1189 
1190 	error = -EIO;
1191 	sb_min_blocksize(sb, 512);
1192 	bh = sb_bread(sb, 0);
1193 	if (bh == NULL) {
1194 		printk(KERN_ERR "FAT: unable to read boot sector\n");
1195 		goto out_fail;
1196 	}
1197 
1198 	b = (struct fat_boot_sector *) bh->b_data;
1199 	if (!b->reserved) {
1200 		if (!silent)
1201 			printk(KERN_ERR "FAT: bogus number of reserved sectors\n");
1202 		brelse(bh);
1203 		goto out_invalid;
1204 	}
1205 	if (!b->fats) {
1206 		if (!silent)
1207 			printk(KERN_ERR "FAT: bogus number of FAT structure\n");
1208 		brelse(bh);
1209 		goto out_invalid;
1210 	}
1211 
1212 	/*
1213 	 * Earlier we checked here that b->secs_track and b->head are nonzero,
1214 	 * but it turns out valid FAT filesystems can have zero there.
1215 	 */
1216 
1217 	media = b->media;
1218 	if (!FAT_VALID_MEDIA(media)) {
1219 		if (!silent)
1220 			printk(KERN_ERR "FAT: invalid media value (0x%02x)\n",
1221 			       media);
1222 		brelse(bh);
1223 		goto out_invalid;
1224 	}
1225 	logical_sector_size =
1226 		le16_to_cpu(get_unaligned((__le16 *)&b->sector_size));
1227 	if (!is_power_of_2(logical_sector_size)
1228 	    || (logical_sector_size < 512)
1229 	    || (PAGE_CACHE_SIZE < logical_sector_size)) {
1230 		if (!silent)
1231 			printk(KERN_ERR "FAT: bogus logical sector size %u\n",
1232 			       logical_sector_size);
1233 		brelse(bh);
1234 		goto out_invalid;
1235 	}
1236 	sbi->sec_per_clus = b->sec_per_clus;
1237 	if (!is_power_of_2(sbi->sec_per_clus)) {
1238 		if (!silent)
1239 			printk(KERN_ERR "FAT: bogus sectors per cluster %u\n",
1240 			       sbi->sec_per_clus);
1241 		brelse(bh);
1242 		goto out_invalid;
1243 	}
1244 
1245 	if (logical_sector_size < sb->s_blocksize) {
1246 		printk(KERN_ERR "FAT: logical sector size too small for device"
1247 		       " (logical sector size = %u)\n", logical_sector_size);
1248 		brelse(bh);
1249 		goto out_fail;
1250 	}
1251 	if (logical_sector_size > sb->s_blocksize) {
1252 		brelse(bh);
1253 
1254 		if (!sb_set_blocksize(sb, logical_sector_size)) {
1255 			printk(KERN_ERR "FAT: unable to set blocksize %u\n",
1256 			       logical_sector_size);
1257 			goto out_fail;
1258 		}
1259 		bh = sb_bread(sb, 0);
1260 		if (bh == NULL) {
1261 			printk(KERN_ERR "FAT: unable to read boot sector"
1262 			       " (logical sector size = %lu)\n",
1263 			       sb->s_blocksize);
1264 			goto out_fail;
1265 		}
1266 		b = (struct fat_boot_sector *) bh->b_data;
1267 	}
1268 
1269 	sbi->cluster_size = sb->s_blocksize * sbi->sec_per_clus;
1270 	sbi->cluster_bits = ffs(sbi->cluster_size) - 1;
1271 	sbi->fats = b->fats;
1272 	sbi->fat_bits = 0;		/* Don't know yet */
1273 	sbi->fat_start = le16_to_cpu(b->reserved);
1274 	sbi->fat_length = le16_to_cpu(b->fat_length);
1275 	sbi->root_cluster = 0;
1276 	sbi->free_clusters = -1;	/* Don't know yet */
1277 	sbi->prev_free = FAT_START_ENT;
1278 
1279 	if (!sbi->fat_length && b->fat32_length) {
1280 		struct fat_boot_fsinfo *fsinfo;
1281 		struct buffer_head *fsinfo_bh;
1282 
1283 		/* Must be FAT32 */
1284 		sbi->fat_bits = 32;
1285 		sbi->fat_length = le32_to_cpu(b->fat32_length);
1286 		sbi->root_cluster = le32_to_cpu(b->root_cluster);
1287 
1288 		sb->s_maxbytes = 0xffffffff;
1289 
1290 		/* MC - if info_sector is 0, don't multiply by 0 */
1291 		sbi->fsinfo_sector = le16_to_cpu(b->info_sector);
1292 		if (sbi->fsinfo_sector == 0)
1293 			sbi->fsinfo_sector = 1;
1294 
1295 		fsinfo_bh = sb_bread(sb, sbi->fsinfo_sector);
1296 		if (fsinfo_bh == NULL) {
1297 			printk(KERN_ERR "FAT: bread failed, FSINFO block"
1298 			       " (sector = %lu)\n", sbi->fsinfo_sector);
1299 			brelse(bh);
1300 			goto out_fail;
1301 		}
1302 
1303 		fsinfo = (struct fat_boot_fsinfo *)fsinfo_bh->b_data;
1304 		if (!IS_FSINFO(fsinfo)) {
1305 			printk(KERN_WARNING
1306 			       "FAT: Did not find valid FSINFO signature.\n"
1307 			       "     Found signature1 0x%08x signature2 0x%08x"
1308 			       " (sector = %lu)\n",
1309 			       le32_to_cpu(fsinfo->signature1),
1310 			       le32_to_cpu(fsinfo->signature2),
1311 			       sbi->fsinfo_sector);
1312 		} else {
1313 			if (sbi->options.usefree)
1314 				sbi->free_clusters =
1315 					le32_to_cpu(fsinfo->free_clusters);
1316 			sbi->prev_free = le32_to_cpu(fsinfo->next_cluster);
1317 		}
1318 
1319 		brelse(fsinfo_bh);
1320 	}
1321 
1322 	sbi->dir_per_block = sb->s_blocksize / sizeof(struct msdos_dir_entry);
1323 	sbi->dir_per_block_bits = ffs(sbi->dir_per_block) - 1;
1324 
1325 	sbi->dir_start = sbi->fat_start + sbi->fats * sbi->fat_length;
1326 	sbi->dir_entries =
1327 		le16_to_cpu(get_unaligned((__le16 *)&b->dir_entries));
1328 	if (sbi->dir_entries & (sbi->dir_per_block - 1)) {
1329 		if (!silent)
1330 			printk(KERN_ERR "FAT: bogus directroy-entries per block"
1331 			       " (%u)\n", sbi->dir_entries);
1332 		brelse(bh);
1333 		goto out_invalid;
1334 	}
1335 
1336 	rootdir_sectors = sbi->dir_entries
1337 		* sizeof(struct msdos_dir_entry) / sb->s_blocksize;
1338 	sbi->data_start = sbi->dir_start + rootdir_sectors;
1339 	total_sectors = le16_to_cpu(get_unaligned((__le16 *)&b->sectors));
1340 	if (total_sectors == 0)
1341 		total_sectors = le32_to_cpu(b->total_sect);
1342 
1343 	total_clusters = (total_sectors - sbi->data_start) / sbi->sec_per_clus;
1344 
1345 	if (sbi->fat_bits != 32)
1346 		sbi->fat_bits = (total_clusters > MAX_FAT12) ? 16 : 12;
1347 
1348 	/* check that FAT table does not overflow */
1349 	fat_clusters = sbi->fat_length * sb->s_blocksize * 8 / sbi->fat_bits;
1350 	total_clusters = min(total_clusters, fat_clusters - FAT_START_ENT);
1351 	if (total_clusters > MAX_FAT(sb)) {
1352 		if (!silent)
1353 			printk(KERN_ERR "FAT: count of clusters too big (%u)\n",
1354 			       total_clusters);
1355 		brelse(bh);
1356 		goto out_invalid;
1357 	}
1358 
1359 	sbi->max_cluster = total_clusters + FAT_START_ENT;
1360 	/* check the free_clusters, it's not necessarily correct */
1361 	if (sbi->free_clusters != -1 && sbi->free_clusters > total_clusters)
1362 		sbi->free_clusters = -1;
1363 	/* check the prev_free, it's not necessarily correct */
1364 	sbi->prev_free %= sbi->max_cluster;
1365 	if (sbi->prev_free < FAT_START_ENT)
1366 		sbi->prev_free = FAT_START_ENT;
1367 
1368 	brelse(bh);
1369 
1370 	/* set up enough so that it can read an inode */
1371 	fat_hash_init(sb);
1372 	fat_ent_access_init(sb);
1373 
1374 	/*
1375 	 * The low byte of FAT's first entry must have same value with
1376 	 * media-field.  But in real world, too many devices is
1377 	 * writing wrong value.  So, removed that validity check.
1378 	 *
1379 	 * if (FAT_FIRST_ENT(sb, media) != first)
1380 	 */
1381 
1382 	error = -EINVAL;
1383 	sprintf(buf, "cp%d", sbi->options.codepage);
1384 	sbi->nls_disk = load_nls(buf);
1385 	if (!sbi->nls_disk) {
1386 		printk(KERN_ERR "FAT: codepage %s not found\n", buf);
1387 		goto out_fail;
1388 	}
1389 
1390 	/* FIXME: utf8 is using iocharset for upper/lower conversion */
1391 	if (sbi->options.isvfat) {
1392 		sbi->nls_io = load_nls(sbi->options.iocharset);
1393 		if (!sbi->nls_io) {
1394 			printk(KERN_ERR "FAT: IO charset %s not found\n",
1395 			       sbi->options.iocharset);
1396 			goto out_fail;
1397 		}
1398 	}
1399 
1400 	error = -ENOMEM;
1401 	root_inode = new_inode(sb);
1402 	if (!root_inode)
1403 		goto out_fail;
1404 	root_inode->i_ino = MSDOS_ROOT_INO;
1405 	root_inode->i_version = 1;
1406 	error = fat_read_root(root_inode);
1407 	if (error < 0)
1408 		goto out_fail;
1409 	error = -ENOMEM;
1410 	insert_inode_hash(root_inode);
1411 	sb->s_root = d_alloc_root(root_inode);
1412 	if (!sb->s_root) {
1413 		printk(KERN_ERR "FAT: get root inode failed\n");
1414 		goto out_fail;
1415 	}
1416 
1417 	return 0;
1418 
1419 out_invalid:
1420 	error = -EINVAL;
1421 	if (!silent)
1422 		printk(KERN_INFO "VFS: Can't find a valid FAT filesystem"
1423 		       " on dev %s.\n", sb->s_id);
1424 
1425 out_fail:
1426 	if (root_inode)
1427 		iput(root_inode);
1428 	if (sbi->nls_io)
1429 		unload_nls(sbi->nls_io);
1430 	if (sbi->nls_disk)
1431 		unload_nls(sbi->nls_disk);
1432 	if (sbi->options.iocharset != fat_default_iocharset)
1433 		kfree(sbi->options.iocharset);
1434 	sb->s_fs_info = NULL;
1435 	kfree(sbi);
1436 	return error;
1437 }
1438 
1439 EXPORT_SYMBOL_GPL(fat_fill_super);
1440 
1441 /*
1442  * helper function for fat_flush_inodes.  This writes both the inode
1443  * and the file data blocks, waiting for in flight data blocks before
1444  * the start of the call.  It does not wait for any io started
1445  * during the call
1446  */
1447 static int writeback_inode(struct inode *inode)
1448 {
1449 
1450 	int ret;
1451 	struct address_space *mapping = inode->i_mapping;
1452 	struct writeback_control wbc = {
1453 	       .sync_mode = WB_SYNC_NONE,
1454 	      .nr_to_write = 0,
1455 	};
1456 	/* if we used WB_SYNC_ALL, sync_inode waits for the io for the
1457 	* inode to finish.  So WB_SYNC_NONE is sent down to sync_inode
1458 	* and filemap_fdatawrite is used for the data blocks
1459 	*/
1460 	ret = sync_inode(inode, &wbc);
1461 	if (!ret)
1462 	       ret = filemap_fdatawrite(mapping);
1463 	return ret;
1464 }
1465 
1466 /*
1467  * write data and metadata corresponding to i1 and i2.  The io is
1468  * started but we do not wait for any of it to finish.
1469  *
1470  * filemap_flush is used for the block device, so if there is a dirty
1471  * page for a block already in flight, we will not wait and start the
1472  * io over again
1473  */
1474 int fat_flush_inodes(struct super_block *sb, struct inode *i1, struct inode *i2)
1475 {
1476 	int ret = 0;
1477 	if (!MSDOS_SB(sb)->options.flush)
1478 		return 0;
1479 	if (i1)
1480 		ret = writeback_inode(i1);
1481 	if (!ret && i2)
1482 		ret = writeback_inode(i2);
1483 	if (!ret) {
1484 		struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping;
1485 		ret = filemap_flush(mapping);
1486 	}
1487 	return ret;
1488 }
1489 EXPORT_SYMBOL_GPL(fat_flush_inodes);
1490 
1491 static int __init init_fat_fs(void)
1492 {
1493 	int err;
1494 
1495 	err = fat_cache_init();
1496 	if (err)
1497 		return err;
1498 
1499 	err = fat_init_inodecache();
1500 	if (err)
1501 		goto failed;
1502 
1503 	return 0;
1504 
1505 failed:
1506 	fat_cache_destroy();
1507 	return err;
1508 }
1509 
1510 static void __exit exit_fat_fs(void)
1511 {
1512 	fat_cache_destroy();
1513 	fat_destroy_inodecache();
1514 }
1515 
1516 module_init(init_fat_fs)
1517 module_exit(exit_fat_fs)
1518 
1519 MODULE_LICENSE("GPL");
1520