xref: /openbmc/linux/fs/fat/inode.c (revision d5cb9783536a41df9f9cba5b0a1d78047ed787f7)
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/buffer_head.h>
22 #include <linux/mount.h>
23 #include <linux/vfs.h>
24 #include <linux/parser.h>
25 #include <asm/unaligned.h>
26 
27 #ifndef CONFIG_FAT_DEFAULT_IOCHARSET
28 /* if user don't select VFAT, this is undefined. */
29 #define CONFIG_FAT_DEFAULT_IOCHARSET	""
30 #endif
31 
32 static int fat_default_codepage = CONFIG_FAT_DEFAULT_CODEPAGE;
33 static char fat_default_iocharset[] = CONFIG_FAT_DEFAULT_IOCHARSET;
34 
35 
36 static int fat_add_cluster(struct inode *inode)
37 {
38 	int err, cluster;
39 
40 	err = fat_alloc_clusters(inode, &cluster, 1);
41 	if (err)
42 		return err;
43 	/* FIXME: this cluster should be added after data of this
44 	 * cluster is writed */
45 	err = fat_chain_add(inode, cluster, 1);
46 	if (err)
47 		fat_free_clusters(inode, cluster);
48 	return err;
49 }
50 
51 static int fat_get_block(struct inode *inode, sector_t iblock,
52 			 struct buffer_head *bh_result, int create)
53 {
54 	struct super_block *sb = inode->i_sb;
55 	sector_t phys;
56 	int err;
57 
58 	err = fat_bmap(inode, iblock, &phys);
59 	if (err)
60 		return err;
61 	if (phys) {
62 		map_bh(bh_result, sb, phys);
63 		return 0;
64 	}
65 	if (!create)
66 		return 0;
67 	if (iblock != MSDOS_I(inode)->mmu_private >> sb->s_blocksize_bits) {
68 		fat_fs_panic(sb, "corrupted file size (i_pos %lld, %lld)",
69 			     MSDOS_I(inode)->i_pos, MSDOS_I(inode)->mmu_private);
70 		return -EIO;
71 	}
72 	if (!((unsigned long)iblock & (MSDOS_SB(sb)->sec_per_clus - 1))) {
73 		err = fat_add_cluster(inode);
74 		if (err)
75 			return err;
76 	}
77 	MSDOS_I(inode)->mmu_private += sb->s_blocksize;
78 	err = fat_bmap(inode, iblock, &phys);
79 	if (err)
80 		return err;
81 	if (!phys)
82 		BUG();
83 	set_buffer_new(bh_result);
84 	map_bh(bh_result, sb, phys);
85 	return 0;
86 }
87 
88 static int fat_writepage(struct page *page, struct writeback_control *wbc)
89 {
90 	return block_write_full_page(page, fat_get_block, wbc);
91 }
92 
93 static int fat_readpage(struct file *file, struct page *page)
94 {
95 	return block_read_full_page(page, fat_get_block);
96 }
97 
98 static int fat_prepare_write(struct file *file, struct page *page,
99 			     unsigned from, unsigned to)
100 {
101 	return cont_prepare_write(page, from, to, fat_get_block,
102 				  &MSDOS_I(page->mapping->host)->mmu_private);
103 }
104 
105 static int fat_commit_write(struct file *file, struct page *page,
106 			    unsigned from, unsigned to)
107 {
108 	struct inode *inode = page->mapping->host;
109 	int err = generic_commit_write(file, page, from, to);
110 	if (!err && !(MSDOS_I(inode)->i_attrs & ATTR_ARCH)) {
111 		inode->i_mtime = inode->i_ctime = CURRENT_TIME_SEC;
112 		MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
113 		mark_inode_dirty(inode);
114 	}
115 	return err;
116 }
117 
118 static sector_t _fat_bmap(struct address_space *mapping, sector_t block)
119 {
120 	return generic_block_bmap(mapping, block, fat_get_block);
121 }
122 
123 static struct address_space_operations fat_aops = {
124 	.readpage	= fat_readpage,
125 	.writepage	= fat_writepage,
126 	.sync_page	= block_sync_page,
127 	.prepare_write	= fat_prepare_write,
128 	.commit_write	= fat_commit_write,
129 	.bmap		= _fat_bmap
130 };
131 
132 /*
133  * New FAT inode stuff. We do the following:
134  *	a) i_ino is constant and has nothing with on-disk location.
135  *	b) FAT manages its own cache of directory entries.
136  *	c) *This* cache is indexed by on-disk location.
137  *	d) inode has an associated directory entry, all right, but
138  *		it may be unhashed.
139  *	e) currently entries are stored within struct inode. That should
140  *		change.
141  *	f) we deal with races in the following way:
142  *		1. readdir() and lookup() do FAT-dir-cache lookup.
143  *		2. rename() unhashes the F-d-c entry and rehashes it in
144  *			a new place.
145  *		3. unlink() and rmdir() unhash F-d-c entry.
146  *		4. fat_write_inode() checks whether the thing is unhashed.
147  *			If it is we silently return. If it isn't we do bread(),
148  *			check if the location is still valid and retry if it
149  *			isn't. Otherwise we do changes.
150  *		5. Spinlock is used to protect hash/unhash/location check/lookup
151  *		6. fat_clear_inode() unhashes the F-d-c entry.
152  *		7. lookup() and readdir() do igrab() if they find a F-d-c entry
153  *			and consider negative result as cache miss.
154  */
155 
156 static void fat_hash_init(struct super_block *sb)
157 {
158 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
159 	int i;
160 
161 	spin_lock_init(&sbi->inode_hash_lock);
162 	for (i = 0; i < FAT_HASH_SIZE; i++)
163 		INIT_HLIST_HEAD(&sbi->inode_hashtable[i]);
164 }
165 
166 static inline unsigned long fat_hash(struct super_block *sb, loff_t i_pos)
167 {
168 	unsigned long tmp = (unsigned long)i_pos | (unsigned long) sb;
169 	tmp = tmp + (tmp >> FAT_HASH_BITS) + (tmp >> FAT_HASH_BITS * 2);
170 	return tmp & FAT_HASH_MASK;
171 }
172 
173 void fat_attach(struct inode *inode, loff_t i_pos)
174 {
175 	struct super_block *sb = inode->i_sb;
176 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
177 
178 	spin_lock(&sbi->inode_hash_lock);
179 	MSDOS_I(inode)->i_pos = i_pos;
180 	hlist_add_head(&MSDOS_I(inode)->i_fat_hash,
181 			sbi->inode_hashtable + fat_hash(sb, i_pos));
182 	spin_unlock(&sbi->inode_hash_lock);
183 }
184 
185 EXPORT_SYMBOL(fat_attach);
186 
187 void fat_detach(struct inode *inode)
188 {
189 	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
190 	spin_lock(&sbi->inode_hash_lock);
191 	MSDOS_I(inode)->i_pos = 0;
192 	hlist_del_init(&MSDOS_I(inode)->i_fat_hash);
193 	spin_unlock(&sbi->inode_hash_lock);
194 }
195 
196 EXPORT_SYMBOL(fat_detach);
197 
198 struct inode *fat_iget(struct super_block *sb, loff_t i_pos)
199 {
200 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
201 	struct hlist_head *head = sbi->inode_hashtable + fat_hash(sb, i_pos);
202 	struct hlist_node *_p;
203 	struct msdos_inode_info *i;
204 	struct inode *inode = NULL;
205 
206 	spin_lock(&sbi->inode_hash_lock);
207 	hlist_for_each_entry(i, _p, head, i_fat_hash) {
208 		BUG_ON(i->vfs_inode.i_sb != sb);
209 		if (i->i_pos != i_pos)
210 			continue;
211 		inode = igrab(&i->vfs_inode);
212 		if (inode)
213 			break;
214 	}
215 	spin_unlock(&sbi->inode_hash_lock);
216 	return inode;
217 }
218 
219 static int is_exec(unsigned char *extension)
220 {
221 	unsigned char *exe_extensions = "EXECOMBAT", *walk;
222 
223 	for (walk = exe_extensions; *walk; walk += 3)
224 		if (!strncmp(extension, walk, 3))
225 			return 1;
226 	return 0;
227 }
228 
229 static int fat_calc_dir_size(struct inode *inode)
230 {
231 	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
232 	int ret, fclus, dclus;
233 
234 	inode->i_size = 0;
235 	if (MSDOS_I(inode)->i_start == 0)
236 		return 0;
237 
238 	ret = fat_get_cluster(inode, FAT_ENT_EOF, &fclus, &dclus);
239 	if (ret < 0)
240 		return ret;
241 	inode->i_size = (fclus + 1) << sbi->cluster_bits;
242 
243 	return 0;
244 }
245 
246 /* doesn't deal with root inode */
247 static int fat_fill_inode(struct inode *inode, struct msdos_dir_entry *de)
248 {
249 	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
250 	int error;
251 
252 	MSDOS_I(inode)->i_pos = 0;
253 	inode->i_uid = sbi->options.fs_uid;
254 	inode->i_gid = sbi->options.fs_gid;
255 	inode->i_version++;
256 	inode->i_generation = get_seconds();
257 
258 	if ((de->attr & ATTR_DIR) && !IS_FREE(de->name)) {
259 		inode->i_generation &= ~1;
260 		inode->i_mode = MSDOS_MKMODE(de->attr,
261 			S_IRWXUGO & ~sbi->options.fs_dmask) | S_IFDIR;
262 		inode->i_op = sbi->dir_ops;
263 		inode->i_fop = &fat_dir_operations;
264 
265 		MSDOS_I(inode)->i_start = le16_to_cpu(de->start);
266 		if (sbi->fat_bits == 32)
267 			MSDOS_I(inode)->i_start |= (le16_to_cpu(de->starthi) << 16);
268 
269 		MSDOS_I(inode)->i_logstart = MSDOS_I(inode)->i_start;
270 		error = fat_calc_dir_size(inode);
271 		if (error < 0)
272 			return error;
273 		MSDOS_I(inode)->mmu_private = inode->i_size;
274 
275 		inode->i_nlink = fat_subdirs(inode);
276 	} else { /* not a directory */
277 		inode->i_generation |= 1;
278 		inode->i_mode = MSDOS_MKMODE(de->attr,
279 		    ((sbi->options.showexec &&
280 			!is_exec(de->ext))
281 			? S_IRUGO|S_IWUGO : S_IRWXUGO)
282 		    & ~sbi->options.fs_fmask) | S_IFREG;
283 		MSDOS_I(inode)->i_start = le16_to_cpu(de->start);
284 		if (sbi->fat_bits == 32)
285 			MSDOS_I(inode)->i_start |= (le16_to_cpu(de->starthi) << 16);
286 
287 		MSDOS_I(inode)->i_logstart = MSDOS_I(inode)->i_start;
288 		inode->i_size = le32_to_cpu(de->size);
289 		inode->i_op = &fat_file_inode_operations;
290 		inode->i_fop = &fat_file_operations;
291 		inode->i_mapping->a_ops = &fat_aops;
292 		MSDOS_I(inode)->mmu_private = inode->i_size;
293 	}
294 	if (de->attr & ATTR_SYS) {
295 		if (sbi->options.sys_immutable)
296 			inode->i_flags |= S_IMMUTABLE;
297 	}
298 	MSDOS_I(inode)->i_attrs = de->attr & ATTR_UNUSED;
299 	/* this is as close to the truth as we can get ... */
300 	inode->i_blksize = sbi->cluster_size;
301 	inode->i_blocks = ((inode->i_size + (sbi->cluster_size - 1))
302 			   & ~((loff_t)sbi->cluster_size - 1)) >> 9;
303 	inode->i_mtime.tv_sec =
304 		date_dos2unix(le16_to_cpu(de->time), le16_to_cpu(de->date));
305 	inode->i_mtime.tv_nsec = 0;
306 	if (sbi->options.isvfat) {
307 		int secs = de->ctime_cs / 100;
308 		int csecs = de->ctime_cs % 100;
309 		inode->i_ctime.tv_sec  =
310 			date_dos2unix(le16_to_cpu(de->ctime),
311 				      le16_to_cpu(de->cdate)) + secs;
312 		inode->i_ctime.tv_nsec = csecs * 10000000;
313 		inode->i_atime.tv_sec =
314 			date_dos2unix(le16_to_cpu(0), le16_to_cpu(de->adate));
315 		inode->i_atime.tv_nsec = 0;
316 	} else
317 		inode->i_ctime = inode->i_atime = inode->i_mtime;
318 
319 	return 0;
320 }
321 
322 struct inode *fat_build_inode(struct super_block *sb,
323 			struct msdos_dir_entry *de, loff_t i_pos)
324 {
325 	struct inode *inode;
326 	int err;
327 
328 	inode = fat_iget(sb, i_pos);
329 	if (inode)
330 		goto out;
331 	inode = new_inode(sb);
332 	if (!inode) {
333 		inode = ERR_PTR(-ENOMEM);
334 		goto out;
335 	}
336 	inode->i_ino = iunique(sb, MSDOS_ROOT_INO);
337 	inode->i_version = 1;
338 	err = fat_fill_inode(inode, de);
339 	if (err) {
340 		iput(inode);
341 		inode = ERR_PTR(err);
342 		goto out;
343 	}
344 	fat_attach(inode, i_pos);
345 	insert_inode_hash(inode);
346 out:
347 	return inode;
348 }
349 
350 EXPORT_SYMBOL(fat_build_inode);
351 
352 static void fat_delete_inode(struct inode *inode)
353 {
354 	truncate_inode_pages(&inode->i_data, 0);
355 
356 	if (!is_bad_inode(inode)) {
357 		inode->i_size = 0;
358 		fat_truncate(inode);
359 	}
360 	clear_inode(inode);
361 }
362 
363 static void fat_clear_inode(struct inode *inode)
364 {
365 	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
366 
367 	if (is_bad_inode(inode))
368 		return;
369 	lock_kernel();
370 	spin_lock(&sbi->inode_hash_lock);
371 	fat_cache_inval_inode(inode);
372 	hlist_del_init(&MSDOS_I(inode)->i_fat_hash);
373 	spin_unlock(&sbi->inode_hash_lock);
374 	unlock_kernel();
375 }
376 
377 static void fat_put_super(struct super_block *sb)
378 {
379 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
380 
381 	if (!(sb->s_flags & MS_RDONLY))
382 		fat_clusters_flush(sb);
383 
384 	if (sbi->nls_disk) {
385 		unload_nls(sbi->nls_disk);
386 		sbi->nls_disk = NULL;
387 		sbi->options.codepage = fat_default_codepage;
388 	}
389 	if (sbi->nls_io) {
390 		unload_nls(sbi->nls_io);
391 		sbi->nls_io = NULL;
392 	}
393 	if (sbi->options.iocharset != fat_default_iocharset) {
394 		kfree(sbi->options.iocharset);
395 		sbi->options.iocharset = fat_default_iocharset;
396 	}
397 
398 	sb->s_fs_info = NULL;
399 	kfree(sbi);
400 }
401 
402 static kmem_cache_t *fat_inode_cachep;
403 
404 static struct inode *fat_alloc_inode(struct super_block *sb)
405 {
406 	struct msdos_inode_info *ei;
407 	ei = kmem_cache_alloc(fat_inode_cachep, SLAB_KERNEL);
408 	if (!ei)
409 		return NULL;
410 	return &ei->vfs_inode;
411 }
412 
413 static void fat_destroy_inode(struct inode *inode)
414 {
415 	kmem_cache_free(fat_inode_cachep, MSDOS_I(inode));
416 }
417 
418 static void init_once(void * foo, kmem_cache_t * cachep, unsigned long flags)
419 {
420 	struct msdos_inode_info *ei = (struct msdos_inode_info *)foo;
421 
422 	if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
423 	    SLAB_CTOR_CONSTRUCTOR) {
424 		spin_lock_init(&ei->cache_lru_lock);
425 		ei->nr_caches = 0;
426 		ei->cache_valid_id = FAT_CACHE_VALID + 1;
427 		INIT_LIST_HEAD(&ei->cache_lru);
428 		INIT_HLIST_NODE(&ei->i_fat_hash);
429 		inode_init_once(&ei->vfs_inode);
430 	}
431 }
432 
433 static int __init fat_init_inodecache(void)
434 {
435 	fat_inode_cachep = kmem_cache_create("fat_inode_cache",
436 					     sizeof(struct msdos_inode_info),
437 					     0, SLAB_RECLAIM_ACCOUNT,
438 					     init_once, NULL);
439 	if (fat_inode_cachep == NULL)
440 		return -ENOMEM;
441 	return 0;
442 }
443 
444 static void __exit fat_destroy_inodecache(void)
445 {
446 	if (kmem_cache_destroy(fat_inode_cachep))
447 		printk(KERN_INFO "fat_inode_cache: not all structures were freed\n");
448 }
449 
450 static int fat_remount(struct super_block *sb, int *flags, char *data)
451 {
452 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
453 	*flags |= MS_NODIRATIME | (sbi->options.isvfat ? 0 : MS_NOATIME);
454 	return 0;
455 }
456 
457 static int fat_statfs(struct super_block *sb, struct kstatfs *buf)
458 {
459 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
460 
461 	/* If the count of free cluster is still unknown, counts it here. */
462 	if (sbi->free_clusters == -1) {
463 		int err = fat_count_free_clusters(sb);
464 		if (err)
465 			return err;
466 	}
467 
468 	buf->f_type = sb->s_magic;
469 	buf->f_bsize = sbi->cluster_size;
470 	buf->f_blocks = sbi->max_cluster - FAT_START_ENT;
471 	buf->f_bfree = sbi->free_clusters;
472 	buf->f_bavail = sbi->free_clusters;
473 	buf->f_namelen = sbi->options.isvfat ? 260 : 12;
474 
475 	return 0;
476 }
477 
478 static int fat_write_inode(struct inode *inode, int wait)
479 {
480 	struct super_block *sb = inode->i_sb;
481 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
482 	struct buffer_head *bh;
483 	struct msdos_dir_entry *raw_entry;
484 	loff_t i_pos;
485 	int err = 0;
486 
487 retry:
488 	i_pos = MSDOS_I(inode)->i_pos;
489 	if (inode->i_ino == MSDOS_ROOT_INO || !i_pos)
490 		return 0;
491 
492 	lock_kernel();
493 	bh = sb_bread(sb, i_pos >> sbi->dir_per_block_bits);
494 	if (!bh) {
495 		printk(KERN_ERR "FAT: unable to read inode block "
496 		       "for updating (i_pos %lld)\n", i_pos);
497 		err = -EIO;
498 		goto out;
499 	}
500 	spin_lock(&sbi->inode_hash_lock);
501 	if (i_pos != MSDOS_I(inode)->i_pos) {
502 		spin_unlock(&sbi->inode_hash_lock);
503 		brelse(bh);
504 		unlock_kernel();
505 		goto retry;
506 	}
507 
508 	raw_entry = &((struct msdos_dir_entry *) (bh->b_data))
509 	    [i_pos & (sbi->dir_per_block - 1)];
510 	if (S_ISDIR(inode->i_mode))
511 		raw_entry->size = 0;
512 	else
513 		raw_entry->size = cpu_to_le32(inode->i_size);
514 	raw_entry->attr = fat_attr(inode);
515 	raw_entry->start = cpu_to_le16(MSDOS_I(inode)->i_logstart);
516 	raw_entry->starthi = cpu_to_le16(MSDOS_I(inode)->i_logstart >> 16);
517 	fat_date_unix2dos(inode->i_mtime.tv_sec, &raw_entry->time, &raw_entry->date);
518 	if (sbi->options.isvfat) {
519 		__le16 atime;
520 		fat_date_unix2dos(inode->i_ctime.tv_sec,&raw_entry->ctime,&raw_entry->cdate);
521 		fat_date_unix2dos(inode->i_atime.tv_sec,&atime,&raw_entry->adate);
522 		raw_entry->ctime_cs = (inode->i_ctime.tv_sec & 1) * 100 +
523 			inode->i_ctime.tv_nsec / 10000000;
524 	}
525 	spin_unlock(&sbi->inode_hash_lock);
526 	mark_buffer_dirty(bh);
527 	if (wait)
528 		err = sync_dirty_buffer(bh);
529 	brelse(bh);
530 out:
531 	unlock_kernel();
532 	return err;
533 }
534 
535 int fat_sync_inode(struct inode *inode)
536 {
537 	return fat_write_inode(inode, 1);
538 }
539 
540 EXPORT_SYMBOL(fat_sync_inode);
541 
542 static int fat_show_options(struct seq_file *m, struct vfsmount *mnt);
543 static struct super_operations fat_sops = {
544 	.alloc_inode	= fat_alloc_inode,
545 	.destroy_inode	= fat_destroy_inode,
546 	.write_inode	= fat_write_inode,
547 	.delete_inode	= fat_delete_inode,
548 	.put_super	= fat_put_super,
549 	.statfs		= fat_statfs,
550 	.clear_inode	= fat_clear_inode,
551 	.remount_fs	= fat_remount,
552 
553 	.read_inode	= make_bad_inode,
554 
555 	.show_options	= fat_show_options,
556 };
557 
558 /*
559  * a FAT file handle with fhtype 3 is
560  *  0/  i_ino - for fast, reliable lookup if still in the cache
561  *  1/  i_generation - to see if i_ino is still valid
562  *          bit 0 == 0 iff directory
563  *  2/  i_pos(8-39) - if ino has changed, but still in cache
564  *  3/  i_pos(4-7)|i_logstart - to semi-verify inode found at i_pos
565  *  4/  i_pos(0-3)|parent->i_logstart - maybe used to hunt for the file on disc
566  *
567  * Hack for NFSv2: Maximum FAT entry number is 28bits and maximum
568  * i_pos is 40bits (blocknr(32) + dir offset(8)), so two 4bits
569  * of i_logstart is used to store the directory entry offset.
570  */
571 
572 static struct dentry *
573 fat_decode_fh(struct super_block *sb, __u32 *fh, int len, int fhtype,
574 	      int (*acceptable)(void *context, struct dentry *de),
575 	      void *context)
576 {
577 	if (fhtype != 3)
578 		return ERR_PTR(-ESTALE);
579 	if (len < 5)
580 		return ERR_PTR(-ESTALE);
581 
582 	return sb->s_export_op->find_exported_dentry(sb, fh, NULL, acceptable, context);
583 }
584 
585 static struct dentry *fat_get_dentry(struct super_block *sb, void *inump)
586 {
587 	struct inode *inode = NULL;
588 	struct dentry *result;
589 	__u32 *fh = inump;
590 
591 	inode = iget(sb, fh[0]);
592 	if (!inode || is_bad_inode(inode) || inode->i_generation != fh[1]) {
593 		if (inode)
594 			iput(inode);
595 		inode = NULL;
596 	}
597 	if (!inode) {
598 		loff_t i_pos;
599 		int i_logstart = fh[3] & 0x0fffffff;
600 
601 		i_pos = (loff_t)fh[2] << 8;
602 		i_pos |= ((fh[3] >> 24) & 0xf0) | (fh[4] >> 28);
603 
604 		/* try 2 - see if i_pos is in F-d-c
605 		 * require i_logstart to be the same
606 		 * Will fail if you truncate and then re-write
607 		 */
608 
609 		inode = fat_iget(sb, i_pos);
610 		if (inode && MSDOS_I(inode)->i_logstart != i_logstart) {
611 			iput(inode);
612 			inode = NULL;
613 		}
614 	}
615 	if (!inode) {
616 		/* For now, do nothing
617 		 * What we could do is:
618 		 * follow the file starting at fh[4], and record
619 		 * the ".." entry, and the name of the fh[2] entry.
620 		 * The follow the ".." file finding the next step up.
621 		 * This way we build a path to the root of
622 		 * the tree. If this works, we lookup the path and so
623 		 * get this inode into the cache.
624 		 * Finally try the fat_iget lookup again
625 		 * If that fails, then weare totally out of luck
626 		 * But all that is for another day
627 		 */
628 	}
629 	if (!inode)
630 		return ERR_PTR(-ESTALE);
631 
632 
633 	/* now to find a dentry.
634 	 * If possible, get a well-connected one
635 	 */
636 	result = d_alloc_anon(inode);
637 	if (result == NULL) {
638 		iput(inode);
639 		return ERR_PTR(-ENOMEM);
640 	}
641 	result->d_op = sb->s_root->d_op;
642 	return result;
643 }
644 
645 static int
646 fat_encode_fh(struct dentry *de, __u32 *fh, int *lenp, int connectable)
647 {
648 	int len = *lenp;
649 	struct inode *inode =  de->d_inode;
650 	u32 ipos_h, ipos_m, ipos_l;
651 
652 	if (len < 5)
653 		return 255; /* no room */
654 
655 	ipos_h = MSDOS_I(inode)->i_pos >> 8;
656 	ipos_m = (MSDOS_I(inode)->i_pos & 0xf0) << 24;
657 	ipos_l = (MSDOS_I(inode)->i_pos & 0x0f) << 28;
658 	*lenp = 5;
659 	fh[0] = inode->i_ino;
660 	fh[1] = inode->i_generation;
661 	fh[2] = ipos_h;
662 	fh[3] = ipos_m | MSDOS_I(inode)->i_logstart;
663 	spin_lock(&de->d_lock);
664 	fh[4] = ipos_l | MSDOS_I(de->d_parent->d_inode)->i_logstart;
665 	spin_unlock(&de->d_lock);
666 	return 3;
667 }
668 
669 static struct dentry *fat_get_parent(struct dentry *child)
670 {
671 	struct buffer_head *bh;
672 	struct msdos_dir_entry *de;
673 	loff_t i_pos;
674 	struct dentry *parent;
675 	struct inode *inode;
676 	int err;
677 
678 	lock_kernel();
679 
680 	err = fat_get_dotdot_entry(child->d_inode, &bh, &de, &i_pos);
681 	if (err) {
682 		parent = ERR_PTR(err);
683 		goto out;
684 	}
685 	inode = fat_build_inode(child->d_sb, de, i_pos);
686 	brelse(bh);
687 	if (IS_ERR(inode)) {
688 		parent = ERR_PTR(PTR_ERR(inode));
689 		goto out;
690 	}
691 	parent = d_alloc_anon(inode);
692 	if (!parent) {
693 		iput(inode);
694 		parent = ERR_PTR(-ENOMEM);
695 	}
696 out:
697 	unlock_kernel();
698 
699 	return parent;
700 }
701 
702 static struct export_operations fat_export_ops = {
703 	.decode_fh	= fat_decode_fh,
704 	.encode_fh	= fat_encode_fh,
705 	.get_dentry	= fat_get_dentry,
706 	.get_parent	= fat_get_parent,
707 };
708 
709 static int fat_show_options(struct seq_file *m, struct vfsmount *mnt)
710 {
711 	struct msdos_sb_info *sbi = MSDOS_SB(mnt->mnt_sb);
712 	struct fat_mount_options *opts = &sbi->options;
713 	int isvfat = opts->isvfat;
714 
715 	if (opts->fs_uid != 0)
716 		seq_printf(m, ",uid=%u", opts->fs_uid);
717 	if (opts->fs_gid != 0)
718 		seq_printf(m, ",gid=%u", opts->fs_gid);
719 	seq_printf(m, ",fmask=%04o", opts->fs_fmask);
720 	seq_printf(m, ",dmask=%04o", opts->fs_dmask);
721 	if (sbi->nls_disk)
722 		seq_printf(m, ",codepage=%s", sbi->nls_disk->charset);
723 	if (isvfat) {
724 		if (sbi->nls_io)
725 			seq_printf(m, ",iocharset=%s", sbi->nls_io->charset);
726 
727 		switch (opts->shortname) {
728 		case VFAT_SFN_DISPLAY_WIN95 | VFAT_SFN_CREATE_WIN95:
729 			seq_puts(m, ",shortname=win95");
730 			break;
731 		case VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WINNT:
732 			seq_puts(m, ",shortname=winnt");
733 			break;
734 		case VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WIN95:
735 			seq_puts(m, ",shortname=mixed");
736 			break;
737 		case VFAT_SFN_DISPLAY_LOWER | VFAT_SFN_CREATE_WIN95:
738 			/* seq_puts(m, ",shortname=lower"); */
739 			break;
740 		default:
741 			seq_puts(m, ",shortname=unknown");
742 			break;
743 		}
744 	}
745 	if (opts->name_check != 'n')
746 		seq_printf(m, ",check=%c", opts->name_check);
747 	if (opts->quiet)
748 		seq_puts(m, ",quiet");
749 	if (opts->showexec)
750 		seq_puts(m, ",showexec");
751 	if (opts->sys_immutable)
752 		seq_puts(m, ",sys_immutable");
753 	if (!isvfat) {
754 		if (opts->dotsOK)
755 			seq_puts(m, ",dotsOK=yes");
756 		if (opts->nocase)
757 			seq_puts(m, ",nocase");
758 	} else {
759 		if (opts->utf8)
760 			seq_puts(m, ",utf8");
761 		if (opts->unicode_xlate)
762 			seq_puts(m, ",uni_xlate");
763 		if (!opts->numtail)
764 			seq_puts(m, ",nonumtail");
765 	}
766 
767 	return 0;
768 }
769 
770 enum {
771 	Opt_check_n, Opt_check_r, Opt_check_s, Opt_uid, Opt_gid,
772 	Opt_umask, Opt_dmask, Opt_fmask, Opt_codepage, Opt_nocase,
773 	Opt_quiet, Opt_showexec, Opt_debug, Opt_immutable,
774 	Opt_dots, Opt_nodots,
775 	Opt_charset, Opt_shortname_lower, Opt_shortname_win95,
776 	Opt_shortname_winnt, Opt_shortname_mixed, Opt_utf8_no, Opt_utf8_yes,
777 	Opt_uni_xl_no, Opt_uni_xl_yes, Opt_nonumtail_no, Opt_nonumtail_yes,
778 	Opt_obsolate, Opt_err,
779 };
780 
781 static match_table_t fat_tokens = {
782 	{Opt_check_r, "check=relaxed"},
783 	{Opt_check_s, "check=strict"},
784 	{Opt_check_n, "check=normal"},
785 	{Opt_check_r, "check=r"},
786 	{Opt_check_s, "check=s"},
787 	{Opt_check_n, "check=n"},
788 	{Opt_uid, "uid=%u"},
789 	{Opt_gid, "gid=%u"},
790 	{Opt_umask, "umask=%o"},
791 	{Opt_dmask, "dmask=%o"},
792 	{Opt_fmask, "fmask=%o"},
793 	{Opt_codepage, "codepage=%u"},
794 	{Opt_nocase, "nocase"},
795 	{Opt_quiet, "quiet"},
796 	{Opt_showexec, "showexec"},
797 	{Opt_debug, "debug"},
798 	{Opt_immutable, "sys_immutable"},
799 	{Opt_obsolate, "conv=binary"},
800 	{Opt_obsolate, "conv=text"},
801 	{Opt_obsolate, "conv=auto"},
802 	{Opt_obsolate, "conv=b"},
803 	{Opt_obsolate, "conv=t"},
804 	{Opt_obsolate, "conv=a"},
805 	{Opt_obsolate, "fat=%u"},
806 	{Opt_obsolate, "blocksize=%u"},
807 	{Opt_obsolate, "cvf_format=%20s"},
808 	{Opt_obsolate, "cvf_options=%100s"},
809 	{Opt_obsolate, "posix"},
810 	{Opt_err, NULL}
811 };
812 static match_table_t msdos_tokens = {
813 	{Opt_nodots, "nodots"},
814 	{Opt_nodots, "dotsOK=no"},
815 	{Opt_dots, "dots"},
816 	{Opt_dots, "dotsOK=yes"},
817 	{Opt_err, NULL}
818 };
819 static match_table_t vfat_tokens = {
820 	{Opt_charset, "iocharset=%s"},
821 	{Opt_shortname_lower, "shortname=lower"},
822 	{Opt_shortname_win95, "shortname=win95"},
823 	{Opt_shortname_winnt, "shortname=winnt"},
824 	{Opt_shortname_mixed, "shortname=mixed"},
825 	{Opt_utf8_no, "utf8=0"},		/* 0 or no or false */
826 	{Opt_utf8_no, "utf8=no"},
827 	{Opt_utf8_no, "utf8=false"},
828 	{Opt_utf8_yes, "utf8=1"},		/* empty or 1 or yes or true */
829 	{Opt_utf8_yes, "utf8=yes"},
830 	{Opt_utf8_yes, "utf8=true"},
831 	{Opt_utf8_yes, "utf8"},
832 	{Opt_uni_xl_no, "uni_xlate=0"},		/* 0 or no or false */
833 	{Opt_uni_xl_no, "uni_xlate=no"},
834 	{Opt_uni_xl_no, "uni_xlate=false"},
835 	{Opt_uni_xl_yes, "uni_xlate=1"},	/* empty or 1 or yes or true */
836 	{Opt_uni_xl_yes, "uni_xlate=yes"},
837 	{Opt_uni_xl_yes, "uni_xlate=true"},
838 	{Opt_uni_xl_yes, "uni_xlate"},
839 	{Opt_nonumtail_no, "nonumtail=0"},	/* 0 or no or false */
840 	{Opt_nonumtail_no, "nonumtail=no"},
841 	{Opt_nonumtail_no, "nonumtail=false"},
842 	{Opt_nonumtail_yes, "nonumtail=1"},	/* empty or 1 or yes or true */
843 	{Opt_nonumtail_yes, "nonumtail=yes"},
844 	{Opt_nonumtail_yes, "nonumtail=true"},
845 	{Opt_nonumtail_yes, "nonumtail"},
846 	{Opt_err, NULL}
847 };
848 
849 static int parse_options(char *options, int is_vfat, int *debug,
850 			 struct fat_mount_options *opts)
851 {
852 	char *p;
853 	substring_t args[MAX_OPT_ARGS];
854 	int option;
855 	char *iocharset;
856 
857 	opts->isvfat = is_vfat;
858 
859 	opts->fs_uid = current->uid;
860 	opts->fs_gid = current->gid;
861 	opts->fs_fmask = opts->fs_dmask = current->fs->umask;
862 	opts->codepage = fat_default_codepage;
863 	opts->iocharset = fat_default_iocharset;
864 	if (is_vfat)
865 		opts->shortname = VFAT_SFN_DISPLAY_LOWER|VFAT_SFN_CREATE_WIN95;
866 	else
867 		opts->shortname = 0;
868 	opts->name_check = 'n';
869 	opts->quiet = opts->showexec = opts->sys_immutable = opts->dotsOK =  0;
870 	opts->utf8 = opts->unicode_xlate = 0;
871 	opts->numtail = 1;
872 	opts->nocase = 0;
873 	*debug = 0;
874 
875 	if (!options)
876 		return 0;
877 
878 	while ((p = strsep(&options, ",")) != NULL) {
879 		int token;
880 		if (!*p)
881 			continue;
882 
883 		token = match_token(p, fat_tokens, args);
884 		if (token == Opt_err) {
885 			if (is_vfat)
886 				token = match_token(p, vfat_tokens, args);
887 			else
888 				token = match_token(p, msdos_tokens, args);
889 		}
890 		switch (token) {
891 		case Opt_check_s:
892 			opts->name_check = 's';
893 			break;
894 		case Opt_check_r:
895 			opts->name_check = 'r';
896 			break;
897 		case Opt_check_n:
898 			opts->name_check = 'n';
899 			break;
900 		case Opt_nocase:
901 			if (!is_vfat)
902 				opts->nocase = 1;
903 			else {
904 				/* for backward compatibility */
905 				opts->shortname = VFAT_SFN_DISPLAY_WIN95
906 					| VFAT_SFN_CREATE_WIN95;
907 			}
908 			break;
909 		case Opt_quiet:
910 			opts->quiet = 1;
911 			break;
912 		case Opt_showexec:
913 			opts->showexec = 1;
914 			break;
915 		case Opt_debug:
916 			*debug = 1;
917 			break;
918 		case Opt_immutable:
919 			opts->sys_immutable = 1;
920 			break;
921 		case Opt_uid:
922 			if (match_int(&args[0], &option))
923 				return 0;
924 			opts->fs_uid = option;
925 			break;
926 		case Opt_gid:
927 			if (match_int(&args[0], &option))
928 				return 0;
929 			opts->fs_gid = option;
930 			break;
931 		case Opt_umask:
932 			if (match_octal(&args[0], &option))
933 				return 0;
934 			opts->fs_fmask = opts->fs_dmask = option;
935 			break;
936 		case Opt_dmask:
937 			if (match_octal(&args[0], &option))
938 				return 0;
939 			opts->fs_dmask = option;
940 			break;
941 		case Opt_fmask:
942 			if (match_octal(&args[0], &option))
943 				return 0;
944 			opts->fs_fmask = option;
945 			break;
946 		case Opt_codepage:
947 			if (match_int(&args[0], &option))
948 				return 0;
949 			opts->codepage = option;
950 			break;
951 
952 		/* msdos specific */
953 		case Opt_dots:
954 			opts->dotsOK = 1;
955 			break;
956 		case Opt_nodots:
957 			opts->dotsOK = 0;
958 			break;
959 
960 		/* vfat specific */
961 		case Opt_charset:
962 			if (opts->iocharset != fat_default_iocharset)
963 				kfree(opts->iocharset);
964 			iocharset = match_strdup(&args[0]);
965 			if (!iocharset)
966 				return -ENOMEM;
967 			opts->iocharset = iocharset;
968 			break;
969 		case Opt_shortname_lower:
970 			opts->shortname = VFAT_SFN_DISPLAY_LOWER
971 					| VFAT_SFN_CREATE_WIN95;
972 			break;
973 		case Opt_shortname_win95:
974 			opts->shortname = VFAT_SFN_DISPLAY_WIN95
975 					| VFAT_SFN_CREATE_WIN95;
976 			break;
977 		case Opt_shortname_winnt:
978 			opts->shortname = VFAT_SFN_DISPLAY_WINNT
979 					| VFAT_SFN_CREATE_WINNT;
980 			break;
981 		case Opt_shortname_mixed:
982 			opts->shortname = VFAT_SFN_DISPLAY_WINNT
983 					| VFAT_SFN_CREATE_WIN95;
984 			break;
985 		case Opt_utf8_no:		/* 0 or no or false */
986 			opts->utf8 = 0;
987 			break;
988 		case Opt_utf8_yes:		/* empty or 1 or yes or true */
989 			opts->utf8 = 1;
990 			break;
991 		case Opt_uni_xl_no:		/* 0 or no or false */
992 			opts->unicode_xlate = 0;
993 			break;
994 		case Opt_uni_xl_yes:		/* empty or 1 or yes or true */
995 			opts->unicode_xlate = 1;
996 			break;
997 		case Opt_nonumtail_no:		/* 0 or no or false */
998 			opts->numtail = 1;	/* negated option */
999 			break;
1000 		case Opt_nonumtail_yes:		/* empty or 1 or yes or true */
1001 			opts->numtail = 0;	/* negated option */
1002 			break;
1003 
1004 		/* obsolete mount options */
1005 		case Opt_obsolate:
1006 			printk(KERN_INFO "FAT: \"%s\" option is obsolete, "
1007 			       "not supported now\n", p);
1008 			break;
1009 		/* unknown option */
1010 		default:
1011 			printk(KERN_ERR "FAT: Unrecognized mount option \"%s\" "
1012 			       "or missing value\n", p);
1013 			return -EINVAL;
1014 		}
1015 	}
1016 	/* UTF8 doesn't provide FAT semantics */
1017 	if (!strcmp(opts->iocharset, "utf8")) {
1018 		printk(KERN_ERR "FAT: utf8 is not a recommended IO charset"
1019 		       " for FAT filesystems, filesystem will be case sensitive!\n");
1020 	}
1021 
1022 	if (opts->unicode_xlate)
1023 		opts->utf8 = 0;
1024 
1025 	return 0;
1026 }
1027 
1028 static int fat_read_root(struct inode *inode)
1029 {
1030 	struct super_block *sb = inode->i_sb;
1031 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
1032 	int error;
1033 
1034 	MSDOS_I(inode)->i_pos = 0;
1035 	inode->i_uid = sbi->options.fs_uid;
1036 	inode->i_gid = sbi->options.fs_gid;
1037 	inode->i_version++;
1038 	inode->i_generation = 0;
1039 	inode->i_mode = (S_IRWXUGO & ~sbi->options.fs_dmask) | S_IFDIR;
1040 	inode->i_op = sbi->dir_ops;
1041 	inode->i_fop = &fat_dir_operations;
1042 	if (sbi->fat_bits == 32) {
1043 		MSDOS_I(inode)->i_start = sbi->root_cluster;
1044 		error = fat_calc_dir_size(inode);
1045 		if (error < 0)
1046 			return error;
1047 	} else {
1048 		MSDOS_I(inode)->i_start = 0;
1049 		inode->i_size = sbi->dir_entries * sizeof(struct msdos_dir_entry);
1050 	}
1051 	inode->i_blksize = sbi->cluster_size;
1052 	inode->i_blocks = ((inode->i_size + (sbi->cluster_size - 1))
1053 			   & ~((loff_t)sbi->cluster_size - 1)) >> 9;
1054 	MSDOS_I(inode)->i_logstart = 0;
1055 	MSDOS_I(inode)->mmu_private = inode->i_size;
1056 
1057 	MSDOS_I(inode)->i_attrs = ATTR_NONE;
1058 	inode->i_mtime.tv_sec = inode->i_atime.tv_sec = inode->i_ctime.tv_sec = 0;
1059 	inode->i_mtime.tv_nsec = inode->i_atime.tv_nsec = inode->i_ctime.tv_nsec = 0;
1060 	inode->i_nlink = fat_subdirs(inode)+2;
1061 
1062 	return 0;
1063 }
1064 
1065 /*
1066  * Read the super block of an MS-DOS FS.
1067  */
1068 int fat_fill_super(struct super_block *sb, void *data, int silent,
1069 		   struct inode_operations *fs_dir_inode_ops, int isvfat)
1070 {
1071 	struct inode *root_inode = NULL;
1072 	struct buffer_head *bh;
1073 	struct fat_boot_sector *b;
1074 	struct msdos_sb_info *sbi;
1075 	u16 logical_sector_size;
1076 	u32 total_sectors, total_clusters, fat_clusters, rootdir_sectors;
1077 	int debug;
1078 	unsigned int media;
1079 	long error;
1080 	char buf[50];
1081 
1082 	sbi = kmalloc(sizeof(struct msdos_sb_info), GFP_KERNEL);
1083 	if (!sbi)
1084 		return -ENOMEM;
1085 	sb->s_fs_info = sbi;
1086 	memset(sbi, 0, sizeof(struct msdos_sb_info));
1087 
1088 	sb->s_flags |= MS_NODIRATIME;
1089 	sb->s_magic = MSDOS_SUPER_MAGIC;
1090 	sb->s_op = &fat_sops;
1091 	sb->s_export_op = &fat_export_ops;
1092 	sbi->dir_ops = fs_dir_inode_ops;
1093 
1094 	error = parse_options(data, isvfat, &debug, &sbi->options);
1095 	if (error)
1096 		goto out_fail;
1097 
1098 	error = -EIO;
1099 	sb_min_blocksize(sb, 512);
1100 	bh = sb_bread(sb, 0);
1101 	if (bh == NULL) {
1102 		printk(KERN_ERR "FAT: unable to read boot sector\n");
1103 		goto out_fail;
1104 	}
1105 
1106 	b = (struct fat_boot_sector *) bh->b_data;
1107 	if (!b->reserved) {
1108 		if (!silent)
1109 			printk(KERN_ERR "FAT: bogus number of reserved sectors\n");
1110 		brelse(bh);
1111 		goto out_invalid;
1112 	}
1113 	if (!b->fats) {
1114 		if (!silent)
1115 			printk(KERN_ERR "FAT: bogus number of FAT structure\n");
1116 		brelse(bh);
1117 		goto out_invalid;
1118 	}
1119 
1120 	/*
1121 	 * Earlier we checked here that b->secs_track and b->head are nonzero,
1122 	 * but it turns out valid FAT filesystems can have zero there.
1123 	 */
1124 
1125 	media = b->media;
1126 	if (!FAT_VALID_MEDIA(media)) {
1127 		if (!silent)
1128 			printk(KERN_ERR "FAT: invalid media value (0x%02x)\n",
1129 			       media);
1130 		brelse(bh);
1131 		goto out_invalid;
1132 	}
1133 	logical_sector_size =
1134 		le16_to_cpu(get_unaligned((__le16 *)&b->sector_size));
1135 	if (!logical_sector_size
1136 	    || (logical_sector_size & (logical_sector_size - 1))
1137 	    || (logical_sector_size < 512)
1138 	    || (PAGE_CACHE_SIZE < logical_sector_size)) {
1139 		if (!silent)
1140 			printk(KERN_ERR "FAT: bogus logical sector size %u\n",
1141 			       logical_sector_size);
1142 		brelse(bh);
1143 		goto out_invalid;
1144 	}
1145 	sbi->sec_per_clus = b->sec_per_clus;
1146 	if (!sbi->sec_per_clus
1147 	    || (sbi->sec_per_clus & (sbi->sec_per_clus - 1))) {
1148 		if (!silent)
1149 			printk(KERN_ERR "FAT: bogus sectors per cluster %u\n",
1150 			       sbi->sec_per_clus);
1151 		brelse(bh);
1152 		goto out_invalid;
1153 	}
1154 
1155 	if (logical_sector_size < sb->s_blocksize) {
1156 		printk(KERN_ERR "FAT: logical sector size too small for device"
1157 		       " (logical sector size = %u)\n", logical_sector_size);
1158 		brelse(bh);
1159 		goto out_fail;
1160 	}
1161 	if (logical_sector_size > sb->s_blocksize) {
1162 		brelse(bh);
1163 
1164 		if (!sb_set_blocksize(sb, logical_sector_size)) {
1165 			printk(KERN_ERR "FAT: unable to set blocksize %u\n",
1166 			       logical_sector_size);
1167 			goto out_fail;
1168 		}
1169 		bh = sb_bread(sb, 0);
1170 		if (bh == NULL) {
1171 			printk(KERN_ERR "FAT: unable to read boot sector"
1172 			       " (logical sector size = %lu)\n",
1173 			       sb->s_blocksize);
1174 			goto out_fail;
1175 		}
1176 		b = (struct fat_boot_sector *) bh->b_data;
1177 	}
1178 
1179 	sbi->cluster_size = sb->s_blocksize * sbi->sec_per_clus;
1180 	sbi->cluster_bits = ffs(sbi->cluster_size) - 1;
1181 	sbi->fats = b->fats;
1182 	sbi->fat_bits = 0;		/* Don't know yet */
1183 	sbi->fat_start = le16_to_cpu(b->reserved);
1184 	sbi->fat_length = le16_to_cpu(b->fat_length);
1185 	sbi->root_cluster = 0;
1186 	sbi->free_clusters = -1;	/* Don't know yet */
1187 	sbi->prev_free = FAT_START_ENT;
1188 
1189 	if (!sbi->fat_length && b->fat32_length) {
1190 		struct fat_boot_fsinfo *fsinfo;
1191 		struct buffer_head *fsinfo_bh;
1192 
1193 		/* Must be FAT32 */
1194 		sbi->fat_bits = 32;
1195 		sbi->fat_length = le32_to_cpu(b->fat32_length);
1196 		sbi->root_cluster = le32_to_cpu(b->root_cluster);
1197 
1198 		sb->s_maxbytes = 0xffffffff;
1199 
1200 		/* MC - if info_sector is 0, don't multiply by 0 */
1201 		sbi->fsinfo_sector = le16_to_cpu(b->info_sector);
1202 		if (sbi->fsinfo_sector == 0)
1203 			sbi->fsinfo_sector = 1;
1204 
1205 		fsinfo_bh = sb_bread(sb, sbi->fsinfo_sector);
1206 		if (fsinfo_bh == NULL) {
1207 			printk(KERN_ERR "FAT: bread failed, FSINFO block"
1208 			       " (sector = %lu)\n", sbi->fsinfo_sector);
1209 			brelse(bh);
1210 			goto out_fail;
1211 		}
1212 
1213 		fsinfo = (struct fat_boot_fsinfo *)fsinfo_bh->b_data;
1214 		if (!IS_FSINFO(fsinfo)) {
1215 			printk(KERN_WARNING
1216 			       "FAT: Did not find valid FSINFO signature.\n"
1217 			       "     Found signature1 0x%08x signature2 0x%08x"
1218 			       " (sector = %lu)\n",
1219 			       le32_to_cpu(fsinfo->signature1),
1220 			       le32_to_cpu(fsinfo->signature2),
1221 			       sbi->fsinfo_sector);
1222 		} else {
1223 			sbi->free_clusters = le32_to_cpu(fsinfo->free_clusters);
1224 			sbi->prev_free = le32_to_cpu(fsinfo->next_cluster);
1225 		}
1226 
1227 		brelse(fsinfo_bh);
1228 	}
1229 
1230 	sbi->dir_per_block = sb->s_blocksize / sizeof(struct msdos_dir_entry);
1231 	sbi->dir_per_block_bits = ffs(sbi->dir_per_block) - 1;
1232 
1233 	sbi->dir_start = sbi->fat_start + sbi->fats * sbi->fat_length;
1234 	sbi->dir_entries =
1235 		le16_to_cpu(get_unaligned((__le16 *)&b->dir_entries));
1236 	if (sbi->dir_entries & (sbi->dir_per_block - 1)) {
1237 		if (!silent)
1238 			printk(KERN_ERR "FAT: bogus directroy-entries per block"
1239 			       " (%u)\n", sbi->dir_entries);
1240 		brelse(bh);
1241 		goto out_invalid;
1242 	}
1243 
1244 	rootdir_sectors = sbi->dir_entries
1245 		* sizeof(struct msdos_dir_entry) / sb->s_blocksize;
1246 	sbi->data_start = sbi->dir_start + rootdir_sectors;
1247 	total_sectors = le16_to_cpu(get_unaligned((__le16 *)&b->sectors));
1248 	if (total_sectors == 0)
1249 		total_sectors = le32_to_cpu(b->total_sect);
1250 
1251 	total_clusters = (total_sectors - sbi->data_start) / sbi->sec_per_clus;
1252 
1253 	if (sbi->fat_bits != 32)
1254 		sbi->fat_bits = (total_clusters > MAX_FAT12) ? 16 : 12;
1255 
1256 	/* check that FAT table does not overflow */
1257 	fat_clusters = sbi->fat_length * sb->s_blocksize * 8 / sbi->fat_bits;
1258 	total_clusters = min(total_clusters, fat_clusters - FAT_START_ENT);
1259 	if (total_clusters > MAX_FAT(sb)) {
1260 		if (!silent)
1261 			printk(KERN_ERR "FAT: count of clusters too big (%u)\n",
1262 			       total_clusters);
1263 		brelse(bh);
1264 		goto out_invalid;
1265 	}
1266 
1267 	sbi->max_cluster = total_clusters + FAT_START_ENT;
1268 	/* check the free_clusters, it's not necessarily correct */
1269 	if (sbi->free_clusters != -1 && sbi->free_clusters > total_clusters)
1270 		sbi->free_clusters = -1;
1271 	/* check the prev_free, it's not necessarily correct */
1272 	sbi->prev_free %= sbi->max_cluster;
1273 	if (sbi->prev_free < FAT_START_ENT)
1274 		sbi->prev_free = FAT_START_ENT;
1275 
1276 	brelse(bh);
1277 
1278 	/* set up enough so that it can read an inode */
1279 	fat_hash_init(sb);
1280 	fat_ent_access_init(sb);
1281 
1282 	/*
1283 	 * The low byte of FAT's first entry must have same value with
1284 	 * media-field.  But in real world, too many devices is
1285 	 * writing wrong value.  So, removed that validity check.
1286 	 *
1287 	 * if (FAT_FIRST_ENT(sb, media) != first)
1288 	 */
1289 
1290 	error = -EINVAL;
1291 	sprintf(buf, "cp%d", sbi->options.codepage);
1292 	sbi->nls_disk = load_nls(buf);
1293 	if (!sbi->nls_disk) {
1294 		printk(KERN_ERR "FAT: codepage %s not found\n", buf);
1295 		goto out_fail;
1296 	}
1297 
1298 	/* FIXME: utf8 is using iocharset for upper/lower conversion */
1299 	if (sbi->options.isvfat) {
1300 		sbi->nls_io = load_nls(sbi->options.iocharset);
1301 		if (!sbi->nls_io) {
1302 			printk(KERN_ERR "FAT: IO charset %s not found\n",
1303 			       sbi->options.iocharset);
1304 			goto out_fail;
1305 		}
1306 	}
1307 
1308 	error = -ENOMEM;
1309 	root_inode = new_inode(sb);
1310 	if (!root_inode)
1311 		goto out_fail;
1312 	root_inode->i_ino = MSDOS_ROOT_INO;
1313 	root_inode->i_version = 1;
1314 	error = fat_read_root(root_inode);
1315 	if (error < 0)
1316 		goto out_fail;
1317 	error = -ENOMEM;
1318 	insert_inode_hash(root_inode);
1319 	sb->s_root = d_alloc_root(root_inode);
1320 	if (!sb->s_root) {
1321 		printk(KERN_ERR "FAT: get root inode failed\n");
1322 		goto out_fail;
1323 	}
1324 
1325 	return 0;
1326 
1327 out_invalid:
1328 	error = -EINVAL;
1329 	if (!silent)
1330 		printk(KERN_INFO "VFS: Can't find a valid FAT filesystem"
1331 		       " on dev %s.\n", sb->s_id);
1332 
1333 out_fail:
1334 	if (root_inode)
1335 		iput(root_inode);
1336 	if (sbi->nls_io)
1337 		unload_nls(sbi->nls_io);
1338 	if (sbi->nls_disk)
1339 		unload_nls(sbi->nls_disk);
1340 	if (sbi->options.iocharset != fat_default_iocharset)
1341 		kfree(sbi->options.iocharset);
1342 	sb->s_fs_info = NULL;
1343 	kfree(sbi);
1344 	return error;
1345 }
1346 
1347 EXPORT_SYMBOL(fat_fill_super);
1348 
1349 int __init fat_cache_init(void);
1350 void fat_cache_destroy(void);
1351 
1352 static int __init init_fat_fs(void)
1353 {
1354 	int err;
1355 
1356 	err = fat_cache_init();
1357 	if (err)
1358 		return err;
1359 
1360 	err = fat_init_inodecache();
1361 	if (err)
1362 		goto failed;
1363 
1364 	return 0;
1365 
1366 failed:
1367 	fat_cache_destroy();
1368 	return err;
1369 }
1370 
1371 static void __exit exit_fat_fs(void)
1372 {
1373 	fat_cache_destroy();
1374 	fat_destroy_inodecache();
1375 }
1376 
1377 module_init(init_fat_fs)
1378 module_exit(exit_fat_fs)
1379 
1380 MODULE_LICENSE("GPL");
1381