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TOMOYO Linux Cross Reference
Linux/fs/fat/inode.c

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

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