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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 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, last_block;
119         int err, offset;
120 
121         err = fat_bmap(inode, iblock, &phys, &mapped_blocks, create, false);
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         last_block = inode->i_blocks >> (sb->s_blocksize_bits - 9);
139         offset = (unsigned long)iblock & (sbi->sec_per_clus - 1);
140         /*
141          * allocate a cluster according to the following.
142          * 1) no more available blocks
143          * 2) not part of fallocate region
144          */
145         if (!offset && !(iblock < last_block)) {
146                 /* TODO: multiple cluster allocation would be desirable. */
147                 err = fat_add_cluster(inode);
148                 if (err)
149                         return err;
150         }
151         /* available blocks on this cluster */
152         mapped_blocks = sbi->sec_per_clus - offset;
153 
154         *max_blocks = min(mapped_blocks, *max_blocks);
155         MSDOS_I(inode)->mmu_private += *max_blocks << sb->s_blocksize_bits;
156 
157         err = fat_bmap(inode, iblock, &phys, &mapped_blocks, create, false);
158         if (err)
159                 return err;
160 
161         BUG_ON(!phys);
162         BUG_ON(*max_blocks != mapped_blocks);
163         set_buffer_new(bh_result);
164         map_bh(bh_result, sb, phys);
165 
166         return 0;
167 }
168 
169 static int fat_get_block(struct inode *inode, sector_t iblock,
170                          struct buffer_head *bh_result, int create)
171 {
172         struct super_block *sb = inode->i_sb;
173         unsigned long max_blocks = bh_result->b_size >> inode->i_blkbits;
174         int err;
175 
176         err = __fat_get_block(inode, iblock, &max_blocks, bh_result, create);
177         if (err)
178                 return err;
179         bh_result->b_size = max_blocks << sb->s_blocksize_bits;
180         return 0;
181 }
182 
183 static int fat_writepage(struct page *page, struct writeback_control *wbc)
184 {
185         return block_write_full_page(page, fat_get_block, wbc);
186 }
187 
188 static int fat_writepages(struct address_space *mapping,
189                           struct writeback_control *wbc)
190 {
191         return mpage_writepages(mapping, wbc, fat_get_block);
192 }
193 
194 static int fat_readpage(struct file *file, struct page *page)
195 {
196         return mpage_readpage(page, fat_get_block);
197 }
198 
199 static int fat_readpages(struct file *file, struct address_space *mapping,
200                          struct list_head *pages, unsigned nr_pages)
201 {
202         return mpage_readpages(mapping, pages, nr_pages, fat_get_block);
203 }
204 
205 static void fat_write_failed(struct address_space *mapping, loff_t to)
206 {
207         struct inode *inode = mapping->host;
208 
209         if (to > inode->i_size) {
210                 truncate_pagecache(inode, inode->i_size);
211                 fat_truncate_blocks(inode, inode->i_size);
212         }
213 }
214 
215 static int fat_write_begin(struct file *file, struct address_space *mapping,
216                         loff_t pos, unsigned len, unsigned flags,
217                         struct page **pagep, void **fsdata)
218 {
219         int err;
220 
221         *pagep = NULL;
222         err = cont_write_begin(file, mapping, pos, len, flags,
223                                 pagep, fsdata, fat_get_block,
224                                 &MSDOS_I(mapping->host)->mmu_private);
225         if (err < 0)
226                 fat_write_failed(mapping, pos + len);
227         return err;
228 }
229 
230 static int fat_write_end(struct file *file, struct address_space *mapping,
231                         loff_t pos, unsigned len, unsigned copied,
232                         struct page *pagep, void *fsdata)
233 {
234         struct inode *inode = mapping->host;
235         int err;
236         err = generic_write_end(file, mapping, pos, len, copied, pagep, fsdata);
237         if (err < len)
238                 fat_write_failed(mapping, pos + len);
239         if (!(err < 0) && !(MSDOS_I(inode)->i_attrs & ATTR_ARCH)) {
240                 inode->i_mtime = inode->i_ctime = current_time(inode);
241                 MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
242                 mark_inode_dirty(inode);
243         }
244         return err;
245 }
246 
247 static ssize_t fat_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
248 {
249         struct file *file = iocb->ki_filp;
250         struct address_space *mapping = file->f_mapping;
251         struct inode *inode = mapping->host;
252         size_t count = iov_iter_count(iter);
253         loff_t offset = iocb->ki_pos;
254         ssize_t ret;
255 
256         if (iov_iter_rw(iter) == WRITE) {
257                 /*
258                  * FIXME: blockdev_direct_IO() doesn't use ->write_begin(),
259                  * so we need to update the ->mmu_private to block boundary.
260                  *
261                  * But we must fill the remaining area or hole by nul for
262                  * updating ->mmu_private.
263                  *
264                  * Return 0, and fallback to normal buffered write.
265                  */
266                 loff_t size = offset + count;
267                 if (MSDOS_I(inode)->mmu_private < size)
268                         return 0;
269         }
270 
271         /*
272          * FAT need to use the DIO_LOCKING for avoiding the race
273          * condition of fat_get_block() and ->truncate().
274          */
275         ret = blockdev_direct_IO(iocb, inode, iter, fat_get_block);
276         if (ret < 0 && iov_iter_rw(iter) == WRITE)
277                 fat_write_failed(mapping, offset + count);
278 
279         return ret;
280 }
281 
282 static int fat_get_block_bmap(struct inode *inode, sector_t iblock,
283                 struct buffer_head *bh_result, int create)
284 {
285         struct super_block *sb = inode->i_sb;
286         unsigned long max_blocks = bh_result->b_size >> inode->i_blkbits;
287         int err;
288         sector_t bmap;
289         unsigned long mapped_blocks;
290 
291         BUG_ON(create != 0);
292 
293         err = fat_bmap(inode, iblock, &bmap, &mapped_blocks, create, true);
294         if (err)
295                 return err;
296 
297         if (bmap) {
298                 map_bh(bh_result, sb, bmap);
299                 max_blocks = min(mapped_blocks, max_blocks);
300         }
301 
302         bh_result->b_size = max_blocks << sb->s_blocksize_bits;
303 
304         return 0;
305 }
306 
307 static sector_t _fat_bmap(struct address_space *mapping, sector_t block)
308 {
309         sector_t blocknr;
310 
311         /* fat_get_cluster() assumes the requested blocknr isn't truncated. */
312         down_read(&MSDOS_I(mapping->host)->truncate_lock);
313         blocknr = generic_block_bmap(mapping, block, fat_get_block_bmap);
314         up_read(&MSDOS_I(mapping->host)->truncate_lock);
315 
316         return blocknr;
317 }
318 
319 /*
320  * fat_block_truncate_page() zeroes out a mapping from file offset `from'
321  * up to the end of the block which corresponds to `from'.
322  * This is required during truncate to physically zeroout the tail end
323  * of that block so it doesn't yield old data if the file is later grown.
324  * Also, avoid causing failure from fsx for cases of "data past EOF"
325  */
326 int fat_block_truncate_page(struct inode *inode, loff_t from)
327 {
328         return block_truncate_page(inode->i_mapping, from, fat_get_block);
329 }
330 
331 static const struct address_space_operations fat_aops = {
332         .readpage       = fat_readpage,
333         .readpages      = fat_readpages,
334         .writepage      = fat_writepage,
335         .writepages     = fat_writepages,
336         .write_begin    = fat_write_begin,
337         .write_end      = fat_write_end,
338         .direct_IO      = fat_direct_IO,
339         .bmap           = _fat_bmap
340 };
341 
342 /*
343  * New FAT inode stuff. We do the following:
344  *      a) i_ino is constant and has nothing with on-disk location.
345  *      b) FAT manages its own cache of directory entries.
346  *      c) *This* cache is indexed by on-disk location.
347  *      d) inode has an associated directory entry, all right, but
348  *              it may be unhashed.
349  *      e) currently entries are stored within struct inode. That should
350  *              change.
351  *      f) we deal with races in the following way:
352  *              1. readdir() and lookup() do FAT-dir-cache lookup.
353  *              2. rename() unhashes the F-d-c entry and rehashes it in
354  *                      a new place.
355  *              3. unlink() and rmdir() unhash F-d-c entry.
356  *              4. fat_write_inode() checks whether the thing is unhashed.
357  *                      If it is we silently return. If it isn't we do bread(),
358  *                      check if the location is still valid and retry if it
359  *                      isn't. Otherwise we do changes.
360  *              5. Spinlock is used to protect hash/unhash/location check/lookup
361  *              6. fat_evict_inode() unhashes the F-d-c entry.
362  *              7. lookup() and readdir() do igrab() if they find a F-d-c entry
363  *                      and consider negative result as cache miss.
364  */
365 
366 static void fat_hash_init(struct super_block *sb)
367 {
368         struct msdos_sb_info *sbi = MSDOS_SB(sb);
369         int i;
370 
371         spin_lock_init(&sbi->inode_hash_lock);
372         for (i = 0; i < FAT_HASH_SIZE; i++)
373                 INIT_HLIST_HEAD(&sbi->inode_hashtable[i]);
374 }
375 
376 static inline unsigned long fat_hash(loff_t i_pos)
377 {
378         return hash_32(i_pos, FAT_HASH_BITS);
379 }
380 
381 static void dir_hash_init(struct super_block *sb)
382 {
383         struct msdos_sb_info *sbi = MSDOS_SB(sb);
384         int i;
385 
386         spin_lock_init(&sbi->dir_hash_lock);
387         for (i = 0; i < FAT_HASH_SIZE; i++)
388                 INIT_HLIST_HEAD(&sbi->dir_hashtable[i]);
389 }
390 
391 void fat_attach(struct inode *inode, loff_t i_pos)
392 {
393         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
394 
395         if (inode->i_ino != MSDOS_ROOT_INO) {
396                 struct hlist_head *head =   sbi->inode_hashtable
397                                           + fat_hash(i_pos);
398 
399                 spin_lock(&sbi->inode_hash_lock);
400                 MSDOS_I(inode)->i_pos = i_pos;
401                 hlist_add_head(&MSDOS_I(inode)->i_fat_hash, head);
402                 spin_unlock(&sbi->inode_hash_lock);
403         }
404 
405         /* If NFS support is enabled, cache the mapping of start cluster
406          * to directory inode. This is used during reconnection of
407          * dentries to the filesystem root.
408          */
409         if (S_ISDIR(inode->i_mode) && sbi->options.nfs) {
410                 struct hlist_head *d_head = sbi->dir_hashtable;
411                 d_head += fat_dir_hash(MSDOS_I(inode)->i_logstart);
412 
413                 spin_lock(&sbi->dir_hash_lock);
414                 hlist_add_head(&MSDOS_I(inode)->i_dir_hash, d_head);
415                 spin_unlock(&sbi->dir_hash_lock);
416         }
417 }
418 EXPORT_SYMBOL_GPL(fat_attach);
419 
420 void fat_detach(struct inode *inode)
421 {
422         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
423         spin_lock(&sbi->inode_hash_lock);
424         MSDOS_I(inode)->i_pos = 0;
425         hlist_del_init(&MSDOS_I(inode)->i_fat_hash);
426         spin_unlock(&sbi->inode_hash_lock);
427 
428         if (S_ISDIR(inode->i_mode) && sbi->options.nfs) {
429                 spin_lock(&sbi->dir_hash_lock);
430                 hlist_del_init(&MSDOS_I(inode)->i_dir_hash);
431                 spin_unlock(&sbi->dir_hash_lock);
432         }
433 }
434 EXPORT_SYMBOL_GPL(fat_detach);
435 
436 struct inode *fat_iget(struct super_block *sb, loff_t i_pos)
437 {
438         struct msdos_sb_info *sbi = MSDOS_SB(sb);
439         struct hlist_head *head = sbi->inode_hashtable + fat_hash(i_pos);
440         struct msdos_inode_info *i;
441         struct inode *inode = NULL;
442 
443         spin_lock(&sbi->inode_hash_lock);
444         hlist_for_each_entry(i, head, i_fat_hash) {
445                 BUG_ON(i->vfs_inode.i_sb != sb);
446                 if (i->i_pos != i_pos)
447                         continue;
448                 inode = igrab(&i->vfs_inode);
449                 if (inode)
450                         break;
451         }
452         spin_unlock(&sbi->inode_hash_lock);
453         return inode;
454 }
455 
456 static int is_exec(unsigned char *extension)
457 {
458         unsigned char exe_extensions[] = "EXECOMBAT", *walk;
459 
460         for (walk = exe_extensions; *walk; walk += 3)
461                 if (!strncmp(extension, walk, 3))
462                         return 1;
463         return 0;
464 }
465 
466 static int fat_calc_dir_size(struct inode *inode)
467 {
468         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
469         int ret, fclus, dclus;
470 
471         inode->i_size = 0;
472         if (MSDOS_I(inode)->i_start == 0)
473                 return 0;
474 
475         ret = fat_get_cluster(inode, FAT_ENT_EOF, &fclus, &dclus);
476         if (ret < 0)
477                 return ret;
478         inode->i_size = (fclus + 1) << sbi->cluster_bits;
479 
480         return 0;
481 }
482 
483 static int fat_validate_dir(struct inode *dir)
484 {
485         struct super_block *sb = dir->i_sb;
486 
487         if (dir->i_nlink < 2) {
488                 /* Directory should have "."/".." entries at least. */
489                 fat_fs_error(sb, "corrupted directory (invalid entries)");
490                 return -EIO;
491         }
492         if (MSDOS_I(dir)->i_start == 0 ||
493             MSDOS_I(dir)->i_start == MSDOS_SB(sb)->root_cluster) {
494                 /* Directory should point valid cluster. */
495                 fat_fs_error(sb, "corrupted directory (invalid i_start)");
496                 return -EIO;
497         }
498         return 0;
499 }
500 
501 /* doesn't deal with root inode */
502 int fat_fill_inode(struct inode *inode, struct msdos_dir_entry *de)
503 {
504         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
505         int error;
506 
507         MSDOS_I(inode)->i_pos = 0;
508         inode->i_uid = sbi->options.fs_uid;
509         inode->i_gid = sbi->options.fs_gid;
510         inode->i_version++;
511         inode->i_generation = get_seconds();
512 
513         if ((de->attr & ATTR_DIR) && !IS_FREE(de->name)) {
514                 inode->i_generation &= ~1;
515                 inode->i_mode = fat_make_mode(sbi, de->attr, S_IRWXUGO);
516                 inode->i_op = sbi->dir_ops;
517                 inode->i_fop = &fat_dir_operations;
518 
519                 MSDOS_I(inode)->i_start = fat_get_start(sbi, de);
520                 MSDOS_I(inode)->i_logstart = MSDOS_I(inode)->i_start;
521                 error = fat_calc_dir_size(inode);
522                 if (error < 0)
523                         return error;
524                 MSDOS_I(inode)->mmu_private = inode->i_size;
525 
526                 set_nlink(inode, fat_subdirs(inode));
527 
528                 error = fat_validate_dir(inode);
529                 if (error < 0)
530                         return error;
531         } else { /* not a directory */
532                 inode->i_generation |= 1;
533                 inode->i_mode = fat_make_mode(sbi, de->attr,
534                         ((sbi->options.showexec && !is_exec(de->name + 8))
535                          ? S_IRUGO|S_IWUGO : S_IRWXUGO));
536                 MSDOS_I(inode)->i_start = fat_get_start(sbi, de);
537 
538                 MSDOS_I(inode)->i_logstart = MSDOS_I(inode)->i_start;
539                 inode->i_size = le32_to_cpu(de->size);
540                 inode->i_op = &fat_file_inode_operations;
541                 inode->i_fop = &fat_file_operations;
542                 inode->i_mapping->a_ops = &fat_aops;
543                 MSDOS_I(inode)->mmu_private = inode->i_size;
544         }
545         if (de->attr & ATTR_SYS) {
546                 if (sbi->options.sys_immutable)
547                         inode->i_flags |= S_IMMUTABLE;
548         }
549         fat_save_attrs(inode, de->attr);
550 
551         inode->i_blocks = ((inode->i_size + (sbi->cluster_size - 1))
552                            & ~((loff_t)sbi->cluster_size - 1)) >> 9;
553 
554         fat_time_fat2unix(sbi, &inode->i_mtime, de->time, de->date, 0);
555         if (sbi->options.isvfat) {
556                 fat_time_fat2unix(sbi, &inode->i_ctime, de->ctime,
557                                   de->cdate, de->ctime_cs);
558                 fat_time_fat2unix(sbi, &inode->i_atime, 0, de->adate, 0);
559         } else
560                 inode->i_ctime = inode->i_atime = inode->i_mtime;
561 
562         return 0;
563 }
564 
565 static inline void fat_lock_build_inode(struct msdos_sb_info *sbi)
566 {
567         if (sbi->options.nfs == FAT_NFS_NOSTALE_RO)
568                 mutex_lock(&sbi->nfs_build_inode_lock);
569 }
570 
571 static inline void fat_unlock_build_inode(struct msdos_sb_info *sbi)
572 {
573         if (sbi->options.nfs == FAT_NFS_NOSTALE_RO)
574                 mutex_unlock(&sbi->nfs_build_inode_lock);
575 }
576 
577 struct inode *fat_build_inode(struct super_block *sb,
578                         struct msdos_dir_entry *de, loff_t i_pos)
579 {
580         struct inode *inode;
581         int err;
582 
583         fat_lock_build_inode(MSDOS_SB(sb));
584         inode = fat_iget(sb, i_pos);
585         if (inode)
586                 goto out;
587         inode = new_inode(sb);
588         if (!inode) {
589                 inode = ERR_PTR(-ENOMEM);
590                 goto out;
591         }
592         inode->i_ino = iunique(sb, MSDOS_ROOT_INO);
593         inode->i_version = 1;
594         err = fat_fill_inode(inode, de);
595         if (err) {
596                 iput(inode);
597                 inode = ERR_PTR(err);
598                 goto out;
599         }
600         fat_attach(inode, i_pos);
601         insert_inode_hash(inode);
602 out:
603         fat_unlock_build_inode(MSDOS_SB(sb));
604         return inode;
605 }
606 
607 EXPORT_SYMBOL_GPL(fat_build_inode);
608 
609 static int __fat_write_inode(struct inode *inode, int wait);
610 
611 static void fat_free_eofblocks(struct inode *inode)
612 {
613         /* Release unwritten fallocated blocks on inode eviction. */
614         if ((inode->i_blocks << 9) >
615                         round_up(MSDOS_I(inode)->mmu_private,
616                                 MSDOS_SB(inode->i_sb)->cluster_size)) {
617                 int err;
618 
619                 fat_truncate_blocks(inode, MSDOS_I(inode)->mmu_private);
620                 /* Fallocate results in updating the i_start/iogstart
621                  * for the zero byte file. So, make it return to
622                  * original state during evict and commit it to avoid
623                  * any corruption on the next access to the cluster
624                  * chain for the file.
625                  */
626                 err = __fat_write_inode(inode, inode_needs_sync(inode));
627                 if (err) {
628                         fat_msg(inode->i_sb, KERN_WARNING, "Failed to "
629                                         "update on disk inode for unused "
630                                         "fallocated blocks, inode could be "
631                                         "corrupted. Please run fsck");
632                 }
633 
634         }
635 }
636 
637 static void fat_evict_inode(struct inode *inode)
638 {
639         truncate_inode_pages_final(&inode->i_data);
640         if (!inode->i_nlink) {
641                 inode->i_size = 0;
642                 fat_truncate_blocks(inode, 0);
643         } else
644                 fat_free_eofblocks(inode);
645 
646         invalidate_inode_buffers(inode);
647         clear_inode(inode);
648         fat_cache_inval_inode(inode);
649         fat_detach(inode);
650 }
651 
652 static void fat_set_state(struct super_block *sb,
653                         unsigned int set, unsigned int force)
654 {
655         struct buffer_head *bh;
656         struct fat_boot_sector *b;
657         struct msdos_sb_info *sbi = MSDOS_SB(sb);
658 
659         /* do not change any thing if mounted read only */
660         if ((sb->s_flags & MS_RDONLY) && !force)
661                 return;
662 
663         /* do not change state if fs was dirty */
664         if (sbi->dirty) {
665                 /* warn only on set (mount). */
666                 if (set)
667                         fat_msg(sb, KERN_WARNING, "Volume was not properly "
668                                 "unmounted. Some data may be corrupt. "
669                                 "Please run fsck.");
670                 return;
671         }
672 
673         bh = sb_bread(sb, 0);
674         if (bh == NULL) {
675                 fat_msg(sb, KERN_ERR, "unable to read boot sector "
676                         "to mark fs as dirty");
677                 return;
678         }
679 
680         b = (struct fat_boot_sector *) bh->b_data;
681 
682         if (sbi->fat_bits == 32) {
683                 if (set)
684                         b->fat32.state |= FAT_STATE_DIRTY;
685                 else
686                         b->fat32.state &= ~FAT_STATE_DIRTY;
687         } else /* fat 16 and 12 */ {
688                 if (set)
689                         b->fat16.state |= FAT_STATE_DIRTY;
690                 else
691                         b->fat16.state &= ~FAT_STATE_DIRTY;
692         }
693 
694         mark_buffer_dirty(bh);
695         sync_dirty_buffer(bh);
696         brelse(bh);
697 }
698 
699 static void delayed_free(struct rcu_head *p)
700 {
701         struct msdos_sb_info *sbi = container_of(p, struct msdos_sb_info, rcu);
702         unload_nls(sbi->nls_disk);
703         unload_nls(sbi->nls_io);
704         if (sbi->options.iocharset != fat_default_iocharset)
705                 kfree(sbi->options.iocharset);
706         kfree(sbi);
707 }
708 
709 static void fat_put_super(struct super_block *sb)
710 {
711         struct msdos_sb_info *sbi = MSDOS_SB(sb);
712 
713         fat_set_state(sb, 0, 0);
714 
715         iput(sbi->fsinfo_inode);
716         iput(sbi->fat_inode);
717 
718         call_rcu(&sbi->rcu, delayed_free);
719 }
720 
721 static struct kmem_cache *fat_inode_cachep;
722 
723 static struct inode *fat_alloc_inode(struct super_block *sb)
724 {
725         struct msdos_inode_info *ei;
726         ei = kmem_cache_alloc(fat_inode_cachep, GFP_NOFS);
727         if (!ei)
728                 return NULL;
729 
730         init_rwsem(&ei->truncate_lock);
731         return &ei->vfs_inode;
732 }
733 
734 static void fat_i_callback(struct rcu_head *head)
735 {
736         struct inode *inode = container_of(head, struct inode, i_rcu);
737         kmem_cache_free(fat_inode_cachep, MSDOS_I(inode));
738 }
739 
740 static void fat_destroy_inode(struct inode *inode)
741 {
742         call_rcu(&inode->i_rcu, fat_i_callback);
743 }
744 
745 static void init_once(void *foo)
746 {
747         struct msdos_inode_info *ei = (struct msdos_inode_info *)foo;
748 
749         spin_lock_init(&ei->cache_lru_lock);
750         ei->nr_caches = 0;
751         ei->cache_valid_id = FAT_CACHE_VALID + 1;
752         INIT_LIST_HEAD(&ei->cache_lru);
753         INIT_HLIST_NODE(&ei->i_fat_hash);
754         INIT_HLIST_NODE(&ei->i_dir_hash);
755         inode_init_once(&ei->vfs_inode);
756 }
757 
758 static int __init fat_init_inodecache(void)
759 {
760         fat_inode_cachep = kmem_cache_create("fat_inode_cache",
761                                              sizeof(struct msdos_inode_info),
762                                              0, (SLAB_RECLAIM_ACCOUNT|
763                                                 SLAB_MEM_SPREAD|SLAB_ACCOUNT),
764                                              init_once);
765         if (fat_inode_cachep == NULL)
766                 return -ENOMEM;
767         return 0;
768 }
769 
770 static void __exit fat_destroy_inodecache(void)
771 {
772         /*
773          * Make sure all delayed rcu free inodes are flushed before we
774          * destroy cache.
775          */
776         rcu_barrier();
777         kmem_cache_destroy(fat_inode_cachep);
778 }
779 
780 static int fat_remount(struct super_block *sb, int *flags, char *data)
781 {
782         int new_rdonly;
783         struct msdos_sb_info *sbi = MSDOS_SB(sb);
784         *flags |= MS_NODIRATIME | (sbi->options.isvfat ? 0 : MS_NOATIME);
785 
786         sync_filesystem(sb);
787 
788         /* make sure we update state on remount. */
789         new_rdonly = *flags & MS_RDONLY;
790         if (new_rdonly != (sb->s_flags & MS_RDONLY)) {
791                 if (new_rdonly)
792                         fat_set_state(sb, 0, 0);
793                 else
794                         fat_set_state(sb, 1, 1);
795         }
796         return 0;
797 }
798 
799 static int fat_statfs(struct dentry *dentry, struct kstatfs *buf)
800 {
801         struct super_block *sb = dentry->d_sb;
802         struct msdos_sb_info *sbi = MSDOS_SB(sb);
803         u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
804 
805         /* If the count of free cluster is still unknown, counts it here. */
806         if (sbi->free_clusters == -1 || !sbi->free_clus_valid) {
807                 int err = fat_count_free_clusters(dentry->d_sb);
808                 if (err)
809                         return err;
810         }
811 
812         buf->f_type = dentry->d_sb->s_magic;
813         buf->f_bsize = sbi->cluster_size;
814         buf->f_blocks = sbi->max_cluster - FAT_START_ENT;
815         buf->f_bfree = sbi->free_clusters;
816         buf->f_bavail = sbi->free_clusters;
817         buf->f_fsid.val[0] = (u32)id;
818         buf->f_fsid.val[1] = (u32)(id >> 32);
819         buf->f_namelen =
820                 (sbi->options.isvfat ? FAT_LFN_LEN : 12) * NLS_MAX_CHARSET_SIZE;
821 
822         return 0;
823 }
824 
825 static int __fat_write_inode(struct inode *inode, int wait)
826 {
827         struct super_block *sb = inode->i_sb;
828         struct msdos_sb_info *sbi = MSDOS_SB(sb);
829         struct buffer_head *bh;
830         struct msdos_dir_entry *raw_entry;
831         loff_t i_pos;
832         sector_t blocknr;
833         int err, offset;
834 
835         if (inode->i_ino == MSDOS_ROOT_INO)
836                 return 0;
837 
838 retry:
839         i_pos = fat_i_pos_read(sbi, inode);
840         if (!i_pos)
841                 return 0;
842 
843         fat_get_blknr_offset(sbi, i_pos, &blocknr, &offset);
844         bh = sb_bread(sb, blocknr);
845         if (!bh) {
846                 fat_msg(sb, KERN_ERR, "unable to read inode block "
847                        "for updating (i_pos %lld)", i_pos);
848                 return -EIO;
849         }
850         spin_lock(&sbi->inode_hash_lock);
851         if (i_pos != MSDOS_I(inode)->i_pos) {
852                 spin_unlock(&sbi->inode_hash_lock);
853                 brelse(bh);
854                 goto retry;
855         }
856 
857         raw_entry = &((struct msdos_dir_entry *) (bh->b_data))[offset];
858         if (S_ISDIR(inode->i_mode))
859                 raw_entry->size = 0;
860         else
861                 raw_entry->size = cpu_to_le32(inode->i_size);
862         raw_entry->attr = fat_make_attrs(inode);
863         fat_set_start(raw_entry, MSDOS_I(inode)->i_logstart);
864         fat_time_unix2fat(sbi, &inode->i_mtime, &raw_entry->time,
865                           &raw_entry->date, NULL);
866         if (sbi->options.isvfat) {
867                 __le16 atime;
868                 fat_time_unix2fat(sbi, &inode->i_ctime, &raw_entry->ctime,
869                                   &raw_entry->cdate, &raw_entry->ctime_cs);
870                 fat_time_unix2fat(sbi, &inode->i_atime, &atime,
871                                   &raw_entry->adate, NULL);
872         }
873         spin_unlock(&sbi->inode_hash_lock);
874         mark_buffer_dirty(bh);
875         err = 0;
876         if (wait)
877                 err = sync_dirty_buffer(bh);
878         brelse(bh);
879         return err;
880 }
881 
882 static int fat_write_inode(struct inode *inode, struct writeback_control *wbc)
883 {
884         int err;
885 
886         if (inode->i_ino == MSDOS_FSINFO_INO) {
887                 struct super_block *sb = inode->i_sb;
888 
889                 mutex_lock(&MSDOS_SB(sb)->s_lock);
890                 err = fat_clusters_flush(sb);
891                 mutex_unlock(&MSDOS_SB(sb)->s_lock);
892         } else
893                 err = __fat_write_inode(inode, wbc->sync_mode == WB_SYNC_ALL);
894 
895         return err;
896 }
897 
898 int fat_sync_inode(struct inode *inode)
899 {
900         return __fat_write_inode(inode, 1);
901 }
902 
903 EXPORT_SYMBOL_GPL(fat_sync_inode);
904 
905 static int fat_show_options(struct seq_file *m, struct dentry *root);
906 static const struct super_operations fat_sops = {
907         .alloc_inode    = fat_alloc_inode,
908         .destroy_inode  = fat_destroy_inode,
909         .write_inode    = fat_write_inode,
910         .evict_inode    = fat_evict_inode,
911         .put_super      = fat_put_super,
912         .statfs         = fat_statfs,
913         .remount_fs     = fat_remount,
914 
915         .show_options   = fat_show_options,
916 };
917 
918 static int fat_show_options(struct seq_file *m, struct dentry *root)
919 {
920         struct msdos_sb_info *sbi = MSDOS_SB(root->d_sb);
921         struct fat_mount_options *opts = &sbi->options;
922         int isvfat = opts->isvfat;
923 
924         if (!uid_eq(opts->fs_uid, GLOBAL_ROOT_UID))
925                 seq_printf(m, ",uid=%u",
926                                 from_kuid_munged(&init_user_ns, opts->fs_uid));
927         if (!gid_eq(opts->fs_gid, GLOBAL_ROOT_GID))
928                 seq_printf(m, ",gid=%u",
929                                 from_kgid_munged(&init_user_ns, opts->fs_gid));
930         seq_printf(m, ",fmask=%04o", opts->fs_fmask);
931         seq_printf(m, ",dmask=%04o", opts->fs_dmask);
932         if (opts->allow_utime)
933                 seq_printf(m, ",allow_utime=%04o", opts->allow_utime);
934         if (sbi->nls_disk)
935                 /* strip "cp" prefix from displayed option */
936                 seq_printf(m, ",codepage=%s", &sbi->nls_disk->charset[2]);
937         if (isvfat) {
938                 if (sbi->nls_io)
939                         seq_printf(m, ",iocharset=%s", sbi->nls_io->charset);
940 
941                 switch (opts->shortname) {
942                 case VFAT_SFN_DISPLAY_WIN95 | VFAT_SFN_CREATE_WIN95:
943                         seq_puts(m, ",shortname=win95");
944                         break;
945                 case VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WINNT:
946                         seq_puts(m, ",shortname=winnt");
947                         break;
948                 case VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WIN95:
949                         seq_puts(m, ",shortname=mixed");
950                         break;
951                 case VFAT_SFN_DISPLAY_LOWER | VFAT_SFN_CREATE_WIN95:
952                         seq_puts(m, ",shortname=lower");
953                         break;
954                 default:
955                         seq_puts(m, ",shortname=unknown");
956                         break;
957                 }
958         }
959         if (opts->name_check != 'n')
960                 seq_printf(m, ",check=%c", opts->name_check);
961         if (opts->usefree)
962                 seq_puts(m, ",usefree");
963         if (opts->quiet)
964                 seq_puts(m, ",quiet");
965         if (opts->showexec)
966                 seq_puts(m, ",showexec");
967         if (opts->sys_immutable)
968                 seq_puts(m, ",sys_immutable");
969         if (!isvfat) {
970                 if (opts->dotsOK)
971                         seq_puts(m, ",dotsOK=yes");
972                 if (opts->nocase)
973                         seq_puts(m, ",nocase");
974         } else {
975                 if (opts->utf8)
976                         seq_puts(m, ",utf8");
977                 if (opts->unicode_xlate)
978                         seq_puts(m, ",uni_xlate");
979                 if (!opts->numtail)
980                         seq_puts(m, ",nonumtail");
981                 if (opts->rodir)
982                         seq_puts(m, ",rodir");
983         }
984         if (opts->flush)
985                 seq_puts(m, ",flush");
986         if (opts->tz_set) {
987                 if (opts->time_offset)
988                         seq_printf(m, ",time_offset=%d", opts->time_offset);
989                 else
990                         seq_puts(m, ",tz=UTC");
991         }
992         if (opts->errors == FAT_ERRORS_CONT)
993                 seq_puts(m, ",errors=continue");
994         else if (opts->errors == FAT_ERRORS_PANIC)
995                 seq_puts(m, ",errors=panic");
996         else
997                 seq_puts(m, ",errors=remount-ro");
998         if (opts->nfs == FAT_NFS_NOSTALE_RO)
999                 seq_puts(m, ",nfs=nostale_ro");
1000         else if (opts->nfs)
1001                 seq_puts(m, ",nfs=stale_rw");
1002         if (opts->discard)
1003                 seq_puts(m, ",discard");
1004         if (opts->dos1xfloppy)
1005                 seq_puts(m, ",dos1xfloppy");
1006 
1007         return 0;
1008 }
1009 
1010 enum {
1011         Opt_check_n, Opt_check_r, Opt_check_s, Opt_uid, Opt_gid,
1012         Opt_umask, Opt_dmask, Opt_fmask, Opt_allow_utime, Opt_codepage,
1013         Opt_usefree, Opt_nocase, Opt_quiet, Opt_showexec, Opt_debug,
1014         Opt_immutable, Opt_dots, Opt_nodots,
1015         Opt_charset, Opt_shortname_lower, Opt_shortname_win95,
1016         Opt_shortname_winnt, Opt_shortname_mixed, Opt_utf8_no, Opt_utf8_yes,
1017         Opt_uni_xl_no, Opt_uni_xl_yes, Opt_nonumtail_no, Opt_nonumtail_yes,
1018         Opt_obsolete, Opt_flush, Opt_tz_utc, Opt_rodir, Opt_err_cont,
1019         Opt_err_panic, Opt_err_ro, Opt_discard, Opt_nfs, Opt_time_offset,
1020         Opt_nfs_stale_rw, Opt_nfs_nostale_ro, Opt_err, Opt_dos1xfloppy,
1021 };
1022 
1023 static const match_table_t fat_tokens = {
1024         {Opt_check_r, "check=relaxed"},
1025         {Opt_check_s, "check=strict"},
1026         {Opt_check_n, "check=normal"},
1027         {Opt_check_r, "check=r"},
1028         {Opt_check_s, "check=s"},
1029         {Opt_check_n, "check=n"},
1030         {Opt_uid, "uid=%u"},
1031         {Opt_gid, "gid=%u"},
1032         {Opt_umask, "umask=%o"},
1033         {Opt_dmask, "dmask=%o"},
1034         {Opt_fmask, "fmask=%o"},
1035         {Opt_allow_utime, "allow_utime=%o"},
1036         {Opt_codepage, "codepage=%u"},
1037         {Opt_usefree, "usefree"},
1038         {Opt_nocase, "nocase"},
1039         {Opt_quiet, "quiet"},
1040         {Opt_showexec, "showexec"},
1041         {Opt_debug, "debug"},
1042         {Opt_immutable, "sys_immutable"},
1043         {Opt_flush, "flush"},
1044         {Opt_tz_utc, "tz=UTC"},
1045         {Opt_time_offset, "time_offset=%d"},
1046         {Opt_err_cont, "errors=continue"},
1047         {Opt_err_panic, "errors=panic"},
1048         {Opt_err_ro, "errors=remount-ro"},
1049         {Opt_discard, "discard"},
1050         {Opt_nfs_stale_rw, "nfs"},
1051         {Opt_nfs_stale_rw, "nfs=stale_rw"},
1052         {Opt_nfs_nostale_ro, "nfs=nostale_ro"},
1053         {Opt_dos1xfloppy, "dos1xfloppy"},
1054         {Opt_obsolete, "conv=binary"},
1055         {Opt_obsolete, "conv=text"},
1056         {Opt_obsolete, "conv=auto"},
1057         {Opt_obsolete, "conv=b"},
1058         {Opt_obsolete, "conv=t"},
1059         {Opt_obsolete, "conv=a"},
1060         {Opt_obsolete, "fat=%u"},
1061         {Opt_obsolete, "blocksize=%u"},
1062         {Opt_obsolete, "cvf_format=%20s"},
1063         {Opt_obsolete, "cvf_options=%100s"},
1064         {Opt_obsolete, "posix"},
1065         {Opt_err, NULL},
1066 };
1067 static const match_table_t msdos_tokens = {
1068         {Opt_nodots, "nodots"},
1069         {Opt_nodots, "dotsOK=no"},
1070         {Opt_dots, "dots"},
1071         {Opt_dots, "dotsOK=yes"},
1072         {Opt_err, NULL}
1073 };
1074 static const match_table_t vfat_tokens = {
1075         {Opt_charset, "iocharset=%s"},
1076         {Opt_shortname_lower, "shortname=lower"},
1077         {Opt_shortname_win95, "shortname=win95"},
1078         {Opt_shortname_winnt, "shortname=winnt"},
1079         {Opt_shortname_mixed, "shortname=mixed"},
1080         {Opt_utf8_no, "utf8=0"},                /* 0 or no or false */
1081         {Opt_utf8_no, "utf8=no"},
1082         {Opt_utf8_no, "utf8=false"},
1083         {Opt_utf8_yes, "utf8=1"},               /* empty or 1 or yes or true */
1084         {Opt_utf8_yes, "utf8=yes"},
1085         {Opt_utf8_yes, "utf8=true"},
1086         {Opt_utf8_yes, "utf8"},
1087         {Opt_uni_xl_no, "uni_xlate=0"},         /* 0 or no or false */
1088         {Opt_uni_xl_no, "uni_xlate=no"},
1089         {Opt_uni_xl_no, "uni_xlate=false"},
1090         {Opt_uni_xl_yes, "uni_xlate=1"},        /* empty or 1 or yes or true */
1091         {Opt_uni_xl_yes, "uni_xlate=yes"},
1092         {Opt_uni_xl_yes, "uni_xlate=true"},
1093         {Opt_uni_xl_yes, "uni_xlate"},
1094         {Opt_nonumtail_no, "nonumtail=0"},      /* 0 or no or false */
1095         {Opt_nonumtail_no, "nonumtail=no"},
1096         {Opt_nonumtail_no, "nonumtail=false"},
1097         {Opt_nonumtail_yes, "nonumtail=1"},     /* empty or 1 or yes or true */
1098         {Opt_nonumtail_yes, "nonumtail=yes"},
1099         {Opt_nonumtail_yes, "nonumtail=true"},
1100         {Opt_nonumtail_yes, "nonumtail"},
1101         {Opt_rodir, "rodir"},
1102         {Opt_err, NULL}
1103 };
1104 
1105 static int parse_options(struct super_block *sb, char *options, int is_vfat,
1106                          int silent, int *debug, struct fat_mount_options *opts)
1107 {
1108         char *p;
1109         substring_t args[MAX_OPT_ARGS];
1110         int option;
1111         char *iocharset;
1112 
1113         opts->isvfat = is_vfat;
1114 
1115         opts->fs_uid = current_uid();
1116         opts->fs_gid = current_gid();
1117         opts->fs_fmask = opts->fs_dmask = current_umask();
1118         opts->allow_utime = -1;
1119         opts->codepage = fat_default_codepage;
1120         opts->iocharset = fat_default_iocharset;
1121         if (is_vfat) {
1122                 opts->shortname = VFAT_SFN_DISPLAY_WINNT|VFAT_SFN_CREATE_WIN95;
1123                 opts->rodir = 0;
1124         } else {
1125                 opts->shortname = 0;
1126                 opts->rodir = 1;
1127         }
1128         opts->name_check = 'n';
1129         opts->quiet = opts->showexec = opts->sys_immutable = opts->dotsOK =  0;
1130         opts->unicode_xlate = 0;
1131         opts->numtail = 1;
1132         opts->usefree = opts->nocase = 0;
1133         opts->tz_set = 0;
1134         opts->nfs = 0;
1135         opts->errors = FAT_ERRORS_RO;
1136         *debug = 0;
1137 
1138         opts->utf8 = IS_ENABLED(CONFIG_FAT_DEFAULT_UTF8) && is_vfat;
1139 
1140         if (!options)
1141                 goto out;
1142 
1143         while ((p = strsep(&options, ",")) != NULL) {
1144                 int token;
1145                 if (!*p)
1146                         continue;
1147 
1148                 token = match_token(p, fat_tokens, args);
1149                 if (token == Opt_err) {
1150                         if (is_vfat)
1151                                 token = match_token(p, vfat_tokens, args);
1152                         else
1153                                 token = match_token(p, msdos_tokens, args);
1154                 }
1155                 switch (token) {
1156                 case Opt_check_s:
1157                         opts->name_check = 's';
1158                         break;
1159                 case Opt_check_r:
1160                         opts->name_check = 'r';
1161                         break;
1162                 case Opt_check_n:
1163                         opts->name_check = 'n';
1164                         break;
1165                 case Opt_usefree:
1166                         opts->usefree = 1;
1167                         break;
1168                 case Opt_nocase:
1169                         if (!is_vfat)
1170                                 opts->nocase = 1;
1171                         else {
1172                                 /* for backward compatibility */
1173                                 opts->shortname = VFAT_SFN_DISPLAY_WIN95
1174                                         | VFAT_SFN_CREATE_WIN95;
1175                         }
1176                         break;
1177                 case Opt_quiet:
1178                         opts->quiet = 1;
1179                         break;
1180                 case Opt_showexec:
1181                         opts->showexec = 1;
1182                         break;
1183                 case Opt_debug:
1184                         *debug = 1;
1185                         break;
1186                 case Opt_immutable:
1187                         opts->sys_immutable = 1;
1188                         break;
1189                 case Opt_uid:
1190                         if (match_int(&args[0], &option))
1191                                 return -EINVAL;
1192                         opts->fs_uid = make_kuid(current_user_ns(), option);
1193                         if (!uid_valid(opts->fs_uid))
1194                                 return -EINVAL;
1195                         break;
1196                 case Opt_gid:
1197                         if (match_int(&args[0], &option))
1198                                 return -EINVAL;
1199                         opts->fs_gid = make_kgid(current_user_ns(), option);
1200                         if (!gid_valid(opts->fs_gid))
1201                                 return -EINVAL;
1202                         break;
1203                 case Opt_umask:
1204                         if (match_octal(&args[0], &option))
1205                                 return -EINVAL;
1206                         opts->fs_fmask = opts->fs_dmask = option;
1207                         break;
1208                 case Opt_dmask:
1209                         if (match_octal(&args[0], &option))
1210                                 return -EINVAL;
1211                         opts->fs_dmask = option;
1212                         break;
1213                 case Opt_fmask:
1214                         if (match_octal(&args[0], &option))
1215                                 return -EINVAL;
1216                         opts->fs_fmask = option;
1217                         break;
1218                 case Opt_allow_utime:
1219                         if (match_octal(&args[0], &option))
1220                                 return -EINVAL;
1221                         opts->allow_utime = option & (S_IWGRP | S_IWOTH);
1222                         break;
1223                 case Opt_codepage:
1224                         if (match_int(&args[0], &option))
1225                                 return -EINVAL;
1226                         opts->codepage = option;
1227                         break;
1228                 case Opt_flush:
1229                         opts->flush = 1;
1230                         break;
1231                 case Opt_time_offset:
1232                         if (match_int(&args[0], &option))
1233                                 return -EINVAL;
1234                         /*
1235                          * GMT+-12 zones may have DST corrections so at least
1236                          * 13 hours difference is needed. Make the limit 24
1237                          * just in case someone invents something unusual.
1238                          */
1239                         if (option < -24 * 60 || option > 24 * 60)
1240                                 return -EINVAL;
1241                         opts->tz_set = 1;
1242                         opts->time_offset = option;
1243                         break;
1244                 case Opt_tz_utc:
1245                         opts->tz_set = 1;
1246                         opts->time_offset = 0;
1247                         break;
1248                 case Opt_err_cont:
1249                         opts->errors = FAT_ERRORS_CONT;
1250                         break;
1251                 case Opt_err_panic:
1252                         opts->errors = FAT_ERRORS_PANIC;
1253                         break;
1254                 case Opt_err_ro:
1255                         opts->errors = FAT_ERRORS_RO;
1256                         break;
1257                 case Opt_nfs_stale_rw:
1258                         opts->nfs = FAT_NFS_STALE_RW;
1259                         break;
1260                 case Opt_nfs_nostale_ro:
1261                         opts->nfs = FAT_NFS_NOSTALE_RO;
1262                         break;
1263                 case Opt_dos1xfloppy:
1264                         opts->dos1xfloppy = 1;
1265                         break;
1266 
1267                 /* msdos specific */
1268                 case Opt_dots:
1269                         opts->dotsOK = 1;
1270                         break;
1271                 case Opt_nodots:
1272                         opts->dotsOK = 0;
1273                         break;
1274 
1275                 /* vfat specific */
1276                 case Opt_charset:
1277                         if (opts->iocharset != fat_default_iocharset)
1278                                 kfree(opts->iocharset);
1279                         iocharset = match_strdup(&args[0]);
1280                         if (!iocharset)
1281                                 return -ENOMEM;
1282                         opts->iocharset = iocharset;
1283                         break;
1284                 case Opt_shortname_lower:
1285                         opts->shortname = VFAT_SFN_DISPLAY_LOWER
1286                                         | VFAT_SFN_CREATE_WIN95;
1287                         break;
1288                 case Opt_shortname_win95:
1289                         opts->shortname = VFAT_SFN_DISPLAY_WIN95
1290                                         | VFAT_SFN_CREATE_WIN95;
1291                         break;
1292                 case Opt_shortname_winnt:
1293                         opts->shortname = VFAT_SFN_DISPLAY_WINNT
1294                                         | VFAT_SFN_CREATE_WINNT;
1295                         break;
1296                 case Opt_shortname_mixed:
1297                         opts->shortname = VFAT_SFN_DISPLAY_WINNT
1298                                         | VFAT_SFN_CREATE_WIN95;
1299                         break;
1300                 case Opt_utf8_no:               /* 0 or no or false */
1301                         opts->utf8 = 0;
1302                         break;
1303                 case Opt_utf8_yes:              /* empty or 1 or yes or true */
1304                         opts->utf8 = 1;
1305                         break;
1306                 case Opt_uni_xl_no:             /* 0 or no or false */
1307                         opts->unicode_xlate = 0;
1308                         break;
1309                 case Opt_uni_xl_yes:            /* empty or 1 or yes or true */
1310                         opts->unicode_xlate = 1;
1311                         break;
1312                 case Opt_nonumtail_no:          /* 0 or no or false */
1313                         opts->numtail = 1;      /* negated option */
1314                         break;
1315                 case Opt_nonumtail_yes:         /* empty or 1 or yes or true */
1316                         opts->numtail = 0;      /* negated option */
1317                         break;
1318                 case Opt_rodir:
1319                         opts->rodir = 1;
1320                         break;
1321                 case Opt_discard:
1322                         opts->discard = 1;
1323                         break;
1324 
1325                 /* obsolete mount options */
1326                 case Opt_obsolete:
1327                         fat_msg(sb, KERN_INFO, "\"%s\" option is obsolete, "
1328                                "not supported now", p);
1329                         break;
1330                 /* unknown option */
1331                 default:
1332                         if (!silent) {
1333                                 fat_msg(sb, KERN_ERR,
1334                                        "Unrecognized mount option \"%s\" "
1335                                        "or missing value", p);
1336                         }
1337                         return -EINVAL;
1338                 }
1339         }
1340 
1341 out:
1342         /* UTF-8 doesn't provide FAT semantics */
1343         if (!strcmp(opts->iocharset, "utf8")) {
1344                 fat_msg(sb, KERN_WARNING, "utf8 is not a recommended IO charset"
1345                        " for FAT filesystems, filesystem will be "
1346                        "case sensitive!");
1347         }
1348 
1349         /* If user doesn't specify allow_utime, it's initialized from dmask. */
1350         if (opts->allow_utime == (unsigned short)-1)
1351                 opts->allow_utime = ~opts->fs_dmask & (S_IWGRP | S_IWOTH);
1352         if (opts->unicode_xlate)
1353                 opts->utf8 = 0;
1354         if (opts->nfs == FAT_NFS_NOSTALE_RO) {
1355                 sb->s_flags |= MS_RDONLY;
1356                 sb->s_export_op = &fat_export_ops_nostale;
1357         }
1358 
1359         return 0;
1360 }
1361 
1362 static void fat_dummy_inode_init(struct inode *inode)
1363 {
1364         /* Initialize this dummy inode to work as no-op. */
1365         MSDOS_I(inode)->mmu_private = 0;
1366         MSDOS_I(inode)->i_start = 0;
1367         MSDOS_I(inode)->i_logstart = 0;
1368         MSDOS_I(inode)->i_attrs = 0;
1369         MSDOS_I(inode)->i_pos = 0;
1370 }
1371 
1372 static int fat_read_root(struct inode *inode)
1373 {
1374         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
1375         int error;
1376 
1377         MSDOS_I(inode)->i_pos = MSDOS_ROOT_INO;
1378         inode->i_uid = sbi->options.fs_uid;
1379         inode->i_gid = sbi->options.fs_gid;
1380         inode->i_version++;
1381         inode->i_generation = 0;
1382         inode->i_mode = fat_make_mode(sbi, ATTR_DIR, S_IRWXUGO);
1383         inode->i_op = sbi->dir_ops;
1384         inode->i_fop = &fat_dir_operations;
1385         if (sbi->fat_bits == 32) {
1386                 MSDOS_I(inode)->i_start = sbi->root_cluster;
1387                 error = fat_calc_dir_size(inode);
1388                 if (error < 0)
1389                         return error;
1390         } else {
1391                 MSDOS_I(inode)->i_start = 0;
1392                 inode->i_size = sbi->dir_entries * sizeof(struct msdos_dir_entry);
1393         }
1394         inode->i_blocks = ((inode->i_size + (sbi->cluster_size - 1))
1395                            & ~((loff_t)sbi->cluster_size - 1)) >> 9;
1396         MSDOS_I(inode)->i_logstart = 0;
1397         MSDOS_I(inode)->mmu_private = inode->i_size;
1398 
1399         fat_save_attrs(inode, ATTR_DIR);
1400         inode->i_mtime.tv_sec = inode->i_atime.tv_sec = inode->i_ctime.tv_sec = 0;
1401         inode->i_mtime.tv_nsec = inode->i_atime.tv_nsec = inode->i_ctime.tv_nsec = 0;
1402         set_nlink(inode, fat_subdirs(inode)+2);
1403 
1404         return 0;
1405 }
1406 
1407 static unsigned long calc_fat_clusters(struct super_block *sb)
1408 {
1409         struct msdos_sb_info *sbi = MSDOS_SB(sb);
1410 
1411         /* Divide first to avoid overflow */
1412         if (sbi->fat_bits != 12) {
1413                 unsigned long ent_per_sec = sb->s_blocksize * 8 / sbi->fat_bits;
1414                 return ent_per_sec * sbi->fat_length;
1415         }
1416 
1417         return sbi->fat_length * sb->s_blocksize * 8 / sbi->fat_bits;
1418 }
1419 
1420 static bool fat_bpb_is_zero(struct fat_boot_sector *b)
1421 {
1422         if (get_unaligned_le16(&b->sector_size))
1423                 return false;
1424         if (b->sec_per_clus)
1425                 return false;
1426         if (b->reserved)
1427                 return false;
1428         if (b->fats)
1429                 return false;
1430         if (get_unaligned_le16(&b->dir_entries))
1431                 return false;
1432         if (get_unaligned_le16(&b->sectors))
1433                 return false;
1434         if (b->media)
1435                 return false;
1436         if (b->fat_length)
1437                 return false;
1438         if (b->secs_track)
1439                 return false;
1440         if (b->heads)
1441                 return false;
1442         return true;
1443 }
1444 
1445 static int fat_read_bpb(struct super_block *sb, struct fat_boot_sector *b,
1446         int silent, struct fat_bios_param_block *bpb)
1447 {
1448         int error = -EINVAL;
1449 
1450         /* Read in BPB ... */
1451         memset(bpb, 0, sizeof(*bpb));
1452         bpb->fat_sector_size = get_unaligned_le16(&b->sector_size);
1453         bpb->fat_sec_per_clus = b->sec_per_clus;
1454         bpb->fat_reserved = le16_to_cpu(b->reserved);
1455         bpb->fat_fats = b->fats;
1456         bpb->fat_dir_entries = get_unaligned_le16(&b->dir_entries);
1457         bpb->fat_sectors = get_unaligned_le16(&b->sectors);
1458         bpb->fat_fat_length = le16_to_cpu(b->fat_length);
1459         bpb->fat_total_sect = le32_to_cpu(b->total_sect);
1460 
1461         bpb->fat16_state = b->fat16.state;
1462         bpb->fat16_vol_id = get_unaligned_le32(b->fat16.vol_id);
1463 
1464         bpb->fat32_length = le32_to_cpu(b->fat32.length);
1465         bpb->fat32_root_cluster = le32_to_cpu(b->fat32.root_cluster);
1466         bpb->fat32_info_sector = le16_to_cpu(b->fat32.info_sector);
1467         bpb->fat32_state = b->fat32.state;
1468         bpb->fat32_vol_id = get_unaligned_le32(b->fat32.vol_id);
1469 
1470         /* Validate this looks like a FAT filesystem BPB */
1471         if (!bpb->fat_reserved) {
1472                 if (!silent)
1473                         fat_msg(sb, KERN_ERR,
1474                                 "bogus number of reserved sectors");
1475                 goto out;
1476         }
1477         if (!bpb->fat_fats) {
1478                 if (!silent)
1479                         fat_msg(sb, KERN_ERR, "bogus number of FAT structure");
1480                 goto out;
1481         }
1482 
1483         /*
1484          * Earlier we checked here that b->secs_track and b->head are nonzero,
1485          * but it turns out valid FAT filesystems can have zero there.
1486          */
1487 
1488         if (!fat_valid_media(b->media)) {
1489                 if (!silent)
1490                         fat_msg(sb, KERN_ERR, "invalid media value (0x%02x)",
1491                                 (unsigned)b->media);
1492                 goto out;
1493         }
1494 
1495         if (!is_power_of_2(bpb->fat_sector_size)
1496             || (bpb->fat_sector_size < 512)
1497             || (bpb->fat_sector_size > 4096)) {
1498                 if (!silent)
1499                         fat_msg(sb, KERN_ERR, "bogus logical sector size %u",
1500                                (unsigned)bpb->fat_sector_size);
1501                 goto out;
1502         }
1503 
1504         if (!is_power_of_2(bpb->fat_sec_per_clus)) {
1505                 if (!silent)
1506                         fat_msg(sb, KERN_ERR, "bogus sectors per cluster %u",
1507                                 (unsigned)bpb->fat_sec_per_clus);
1508                 goto out;
1509         }
1510 
1511         error = 0;
1512 
1513 out:
1514         return error;
1515 }
1516 
1517 static int fat_read_static_bpb(struct super_block *sb,
1518         struct fat_boot_sector *b, int silent,
1519         struct fat_bios_param_block *bpb)
1520 {
1521         static const char *notdos1x = "This doesn't look like a DOS 1.x volume";
1522 
1523         struct fat_floppy_defaults *fdefaults = NULL;
1524         int error = -EINVAL;
1525         sector_t bd_sects;
1526         unsigned i;
1527 
1528         bd_sects = i_size_read(sb->s_bdev->bd_inode) / SECTOR_SIZE;
1529 
1530         /* 16-bit DOS 1.x reliably wrote bootstrap short-jmp code */
1531         if (b->ignored[0] != 0xeb || b->ignored[2] != 0x90) {
1532                 if (!silent)
1533                         fat_msg(sb, KERN_ERR,
1534                                 "%s; no bootstrapping code", notdos1x);
1535                 goto out;
1536         }
1537 
1538         /*
1539          * If any value in this region is non-zero, it isn't archaic
1540          * DOS.
1541          */
1542         if (!fat_bpb_is_zero(b)) {
1543                 if (!silent)
1544                         fat_msg(sb, KERN_ERR,
1545                                 "%s; DOS 2.x BPB is non-zero", notdos1x);
1546                 goto out;
1547         }
1548 
1549         for (i = 0; i < ARRAY_SIZE(floppy_defaults); i++) {
1550                 if (floppy_defaults[i].nr_sectors == bd_sects) {
1551                         fdefaults = &floppy_defaults[i];
1552                         break;
1553                 }
1554         }
1555 
1556         if (fdefaults == NULL) {
1557                 if (!silent)
1558                         fat_msg(sb, KERN_WARNING,
1559                                 "This looks like a DOS 1.x volume, but isn't a recognized floppy size (%llu sectors)",
1560                                 (u64)bd_sects);
1561                 goto out;
1562         }
1563 
1564         if (!silent)
1565                 fat_msg(sb, KERN_INFO,
1566                         "This looks like a DOS 1.x volume; assuming default BPB values");
1567 
1568         memset(bpb, 0, sizeof(*bpb));
1569         bpb->fat_sector_size = SECTOR_SIZE;
1570         bpb->fat_sec_per_clus = fdefaults->sec_per_clus;
1571         bpb->fat_reserved = 1;
1572         bpb->fat_fats = 2;
1573         bpb->fat_dir_entries = fdefaults->dir_entries;
1574         bpb->fat_sectors = fdefaults->nr_sectors;
1575         bpb->fat_fat_length = fdefaults->fat_length;
1576 
1577         error = 0;
1578 
1579 out:
1580         return error;
1581 }
1582 
1583 /*
1584  * Read the super block of an MS-DOS FS.
1585  */
1586 int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat,
1587                    void (*setup)(struct super_block *))
1588 {
1589         struct inode *root_inode = NULL, *fat_inode = NULL;
1590         struct inode *fsinfo_inode = NULL;
1591         struct buffer_head *bh;
1592         struct fat_bios_param_block bpb;
1593         struct msdos_sb_info *sbi;
1594         u16 logical_sector_size;
1595         u32 total_sectors, total_clusters, fat_clusters, rootdir_sectors;
1596         int debug;
1597         long error;
1598         char buf[50];
1599 
1600         /*
1601          * GFP_KERNEL is ok here, because while we do hold the
1602          * superblock lock, memory pressure can't call back into
1603          * the filesystem, since we're only just about to mount
1604          * it and have no inodes etc active!
1605          */
1606         sbi = kzalloc(sizeof(struct msdos_sb_info), GFP_KERNEL);
1607         if (!sbi)
1608                 return -ENOMEM;
1609         sb->s_fs_info = sbi;
1610 
1611         sb->s_flags |= MS_NODIRATIME;
1612         sb->s_magic = MSDOS_SUPER_MAGIC;
1613         sb->s_op = &fat_sops;
1614         sb->s_export_op = &fat_export_ops;
1615         mutex_init(&sbi->nfs_build_inode_lock);
1616         ratelimit_state_init(&sbi->ratelimit, DEFAULT_RATELIMIT_INTERVAL,
1617                              DEFAULT_RATELIMIT_BURST);
1618 
1619         error = parse_options(sb, data, isvfat, silent, &debug, &sbi->options);
1620         if (error)
1621                 goto out_fail;
1622 
1623         setup(sb); /* flavour-specific stuff that needs options */
1624 
1625         error = -EIO;
1626         sb_min_blocksize(sb, 512);
1627         bh = sb_bread(sb, 0);
1628         if (bh == NULL) {
1629                 fat_msg(sb, KERN_ERR, "unable to read boot sector");
1630                 goto out_fail;
1631         }
1632 
1633         error = fat_read_bpb(sb, (struct fat_boot_sector *)bh->b_data, silent,
1634                 &bpb);
1635         if (error == -EINVAL && sbi->options.dos1xfloppy)
1636                 error = fat_read_static_bpb(sb,
1637                         (struct fat_boot_sector *)bh->b_data, silent, &bpb);
1638         brelse(bh);
1639 
1640         if (error == -EINVAL)
1641                 goto out_invalid;
1642         else if (error)
1643                 goto out_fail;
1644 
1645         logical_sector_size = bpb.fat_sector_size;
1646         sbi->sec_per_clus = bpb.fat_sec_per_clus;
1647 
1648         error = -EIO;
1649         if (logical_sector_size < sb->s_blocksize) {
1650                 fat_msg(sb, KERN_ERR, "logical sector size too small for device"
1651                        " (logical sector size = %u)", logical_sector_size);
1652                 goto out_fail;
1653         }
1654 
1655         if (logical_sector_size > sb->s_blocksize) {
1656                 struct buffer_head *bh_resize;
1657 
1658                 if (!sb_set_blocksize(sb, logical_sector_size)) {
1659                         fat_msg(sb, KERN_ERR, "unable to set blocksize %u",
1660                                logical_sector_size);
1661                         goto out_fail;
1662                 }
1663 
1664                 /* Verify that the larger boot sector is fully readable */
1665                 bh_resize = sb_bread(sb, 0);
1666                 if (bh_resize == NULL) {
1667                         fat_msg(sb, KERN_ERR, "unable to read boot sector"
1668                                " (logical sector size = %lu)",
1669                                sb->s_blocksize);
1670                         goto out_fail;
1671                 }
1672                 brelse(bh_resize);
1673         }
1674 
1675         mutex_init(&sbi->s_lock);
1676         sbi->cluster_size = sb->s_blocksize * sbi->sec_per_clus;
1677         sbi->cluster_bits = ffs(sbi->cluster_size) - 1;
1678         sbi->fats = bpb.fat_fats;
1679         sbi->fat_bits = 0;              /* Don't know yet */
1680         sbi->fat_start = bpb.fat_reserved;
1681         sbi->fat_length = bpb.fat_fat_length;
1682         sbi->root_cluster = 0;
1683         sbi->free_clusters = -1;        /* Don't know yet */
1684         sbi->free_clus_valid = 0;
1685         sbi->prev_free = FAT_START_ENT;
1686         sb->s_maxbytes = 0xffffffff;
1687 
1688         if (!sbi->fat_length && bpb.fat32_length) {
1689                 struct fat_boot_fsinfo *fsinfo;
1690                 struct buffer_head *fsinfo_bh;
1691 
1692                 /* Must be FAT32 */
1693                 sbi->fat_bits = 32;
1694                 sbi->fat_length = bpb.fat32_length;
1695                 sbi->root_cluster = bpb.fat32_root_cluster;
1696 
1697                 /* MC - if info_sector is 0, don't multiply by 0 */
1698                 sbi->fsinfo_sector = bpb.fat32_info_sector;
1699                 if (sbi->fsinfo_sector == 0)
1700                         sbi->fsinfo_sector = 1;
1701 
1702                 fsinfo_bh = sb_bread(sb, sbi->fsinfo_sector);
1703                 if (fsinfo_bh == NULL) {
1704                         fat_msg(sb, KERN_ERR, "bread failed, FSINFO block"
1705                                " (sector = %lu)", sbi->fsinfo_sector);
1706                         goto out_fail;
1707                 }
1708 
1709                 fsinfo = (struct fat_boot_fsinfo *)fsinfo_bh->b_data;
1710                 if (!IS_FSINFO(fsinfo)) {
1711                         fat_msg(sb, KERN_WARNING, "Invalid FSINFO signature: "
1712                                "0x%08x, 0x%08x (sector = %lu)",
1713                                le32_to_cpu(fsinfo->signature1),
1714                                le32_to_cpu(fsinfo->signature2),
1715                                sbi->fsinfo_sector);
1716                 } else {
1717                         if (sbi->options.usefree)
1718                                 sbi->free_clus_valid = 1;
1719                         sbi->free_clusters = le32_to_cpu(fsinfo->free_clusters);
1720                         sbi->prev_free = le32_to_cpu(fsinfo->next_cluster);
1721                 }
1722 
1723                 brelse(fsinfo_bh);
1724         }
1725 
1726         /* interpret volume ID as a little endian 32 bit integer */
1727         if (sbi->fat_bits == 32)
1728                 sbi->vol_id = bpb.fat32_vol_id;
1729         else /* fat 16 or 12 */
1730                 sbi->vol_id = bpb.fat16_vol_id;
1731 
1732         sbi->dir_per_block = sb->s_blocksize / sizeof(struct msdos_dir_entry);
1733         sbi->dir_per_block_bits = ffs(sbi->dir_per_block) - 1;
1734 
1735         sbi->dir_start = sbi->fat_start + sbi->fats * sbi->fat_length;
1736         sbi->dir_entries = bpb.fat_dir_entries;
1737         if (sbi->dir_entries & (sbi->dir_per_block - 1)) {
1738                 if (!silent)
1739                         fat_msg(sb, KERN_ERR, "bogus number of directory entries"
1740                                " (%u)", sbi->dir_entries);
1741                 goto out_invalid;
1742         }
1743 
1744         rootdir_sectors = sbi->dir_entries
1745                 * sizeof(struct msdos_dir_entry) / sb->s_blocksize;
1746         sbi->data_start = sbi->dir_start + rootdir_sectors;
1747         total_sectors = bpb.fat_sectors;
1748         if (total_sectors == 0)
1749                 total_sectors = bpb.fat_total_sect;
1750 
1751         total_clusters = (total_sectors - sbi->data_start) / sbi->sec_per_clus;
1752 
1753         if (sbi->fat_bits != 32)
1754                 sbi->fat_bits = (total_clusters > MAX_FAT12) ? 16 : 12;
1755 
1756         /* some OSes set FAT_STATE_DIRTY and clean it on unmount. */
1757         if (sbi->fat_bits == 32)
1758                 sbi->dirty = bpb.fat32_state & FAT_STATE_DIRTY;
1759         else /* fat 16 or 12 */
1760                 sbi->dirty = bpb.fat16_state & FAT_STATE_DIRTY;
1761 
1762         /* check that FAT table does not overflow */
1763         fat_clusters = calc_fat_clusters(sb);
1764         total_clusters = min(total_clusters, fat_clusters - FAT_START_ENT);
1765         if (total_clusters > MAX_FAT(sb)) {
1766                 if (!silent)
1767                         fat_msg(sb, KERN_ERR, "count of clusters too big (%u)",
1768                                total_clusters);
1769                 goto out_invalid;
1770         }
1771 
1772         sbi->max_cluster = total_clusters + FAT_START_ENT;
1773         /* check the free_clusters, it's not necessarily correct */
1774         if (sbi->free_clusters != -1 && sbi->free_clusters > total_clusters)
1775                 sbi->free_clusters = -1;
1776         /* check the prev_free, it's not necessarily correct */
1777         sbi->prev_free %= sbi->max_cluster;
1778         if (sbi->prev_free < FAT_START_ENT)
1779                 sbi->prev_free = FAT_START_ENT;
1780 
1781         /* set up enough so that it can read an inode */
1782         fat_hash_init(sb);
1783         dir_hash_init(sb);
1784         fat_ent_access_init(sb);
1785 
1786         /*
1787          * The low byte of FAT's first entry must have same value with
1788          * media-field.  But in real world, too many devices is
1789          * writing wrong value.  So, removed that validity check.
1790          *
1791          * if (FAT_FIRST_ENT(sb, media) != first)
1792          */
1793 
1794         error = -EINVAL;
1795         sprintf(buf, "cp%d", sbi->options.codepage);
1796         sbi->nls_disk = load_nls(buf);
1797         if (!sbi->nls_disk) {
1798                 fat_msg(sb, KERN_ERR, "codepage %s not found", buf);
1799                 goto out_fail;
1800         }
1801 
1802         /* FIXME: utf8 is using iocharset for upper/lower conversion */
1803         if (sbi->options.isvfat) {
1804                 sbi->nls_io = load_nls(sbi->options.iocharset);
1805                 if (!sbi->nls_io) {
1806                         fat_msg(sb, KERN_ERR, "IO charset %s not found",
1807                                sbi->options.iocharset);
1808                         goto out_fail;
1809                 }
1810         }
1811 
1812         error = -ENOMEM;
1813         fat_inode = new_inode(sb);
1814         if (!fat_inode)
1815                 goto out_fail;
1816         fat_dummy_inode_init(fat_inode);
1817         sbi->fat_inode = fat_inode;
1818 
1819         fsinfo_inode = new_inode(sb);
1820         if (!fsinfo_inode)
1821                 goto out_fail;
1822         fat_dummy_inode_init(fsinfo_inode);
1823         fsinfo_inode->i_ino = MSDOS_FSINFO_INO;
1824         sbi->fsinfo_inode = fsinfo_inode;
1825         insert_inode_hash(fsinfo_inode);
1826 
1827         root_inode = new_inode(sb);
1828         if (!root_inode)
1829                 goto out_fail;
1830         root_inode->i_ino = MSDOS_ROOT_INO;
1831         root_inode->i_version = 1;
1832         error = fat_read_root(root_inode);
1833         if (error < 0) {
1834                 iput(root_inode);
1835                 goto out_fail;
1836         }
1837         error = -ENOMEM;
1838         insert_inode_hash(root_inode);
1839         fat_attach(root_inode, 0);
1840         sb->s_root = d_make_root(root_inode);
1841         if (!sb->s_root) {
1842                 fat_msg(sb, KERN_ERR, "get root inode failed");
1843                 goto out_fail;
1844         }
1845 
1846         if (sbi->options.discard) {
1847                 struct request_queue *q = bdev_get_queue(sb->s_bdev);
1848                 if (!blk_queue_discard(q))
1849                         fat_msg(sb, KERN_WARNING,
1850                                         "mounting with \"discard\" option, but "
1851                                         "the device does not support discard");
1852         }
1853 
1854         fat_set_state(sb, 1, 0);
1855         return 0;
1856 
1857 out_invalid:
1858         error = -EINVAL;
1859         if (!silent)
1860                 fat_msg(sb, KERN_INFO, "Can't find a valid FAT filesystem");
1861 
1862 out_fail:
1863         if (fsinfo_inode)
1864                 iput(fsinfo_inode);
1865         if (fat_inode)
1866                 iput(fat_inode);
1867         unload_nls(sbi->nls_io);
1868         unload_nls(sbi->nls_disk);
1869         if (sbi->options.iocharset != fat_default_iocharset)
1870                 kfree(sbi->options.iocharset);
1871         sb->s_fs_info = NULL;
1872         kfree(sbi);
1873         return error;
1874 }
1875 
1876 EXPORT_SYMBOL_GPL(fat_fill_super);
1877 
1878 /*
1879  * helper function for fat_flush_inodes.  This writes both the inode
1880  * and the file data blocks, waiting for in flight data blocks before
1881  * the start of the call.  It does not wait for any io started
1882  * during the call
1883  */
1884 static int writeback_inode(struct inode *inode)
1885 {
1886 
1887         int ret;
1888 
1889         /* if we used wait=1, sync_inode_metadata waits for the io for the
1890         * inode to finish.  So wait=0 is sent down to sync_inode_metadata
1891         * and filemap_fdatawrite is used for the data blocks
1892         */
1893         ret = sync_inode_metadata(inode, 0);
1894         if (!ret)
1895                 ret = filemap_fdatawrite(inode->i_mapping);
1896         return ret;
1897 }
1898 
1899 /*
1900  * write data and metadata corresponding to i1 and i2.  The io is
1901  * started but we do not wait for any of it to finish.
1902  *
1903  * filemap_flush is used for the block device, so if there is a dirty
1904  * page for a block already in flight, we will not wait and start the
1905  * io over again
1906  */
1907 int fat_flush_inodes(struct super_block *sb, struct inode *i1, struct inode *i2)
1908 {
1909         int ret = 0;
1910         if (!MSDOS_SB(sb)->options.flush)
1911                 return 0;
1912         if (i1)
1913                 ret = writeback_inode(i1);
1914         if (!ret && i2)
1915                 ret = writeback_inode(i2);
1916         if (!ret) {
1917                 struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping;
1918                 ret = filemap_flush(mapping);
1919         }
1920         return ret;
1921 }
1922 EXPORT_SYMBOL_GPL(fat_flush_inodes);
1923 
1924 static int __init init_fat_fs(void)
1925 {
1926         int err;
1927 
1928         err = fat_cache_init();
1929         if (err)
1930                 return err;
1931 
1932         err = fat_init_inodecache();
1933         if (err)
1934                 goto failed;
1935 
1936         return 0;
1937 
1938 failed:
1939         fat_cache_destroy();
1940         return err;
1941 }
1942 
1943 static void __exit exit_fat_fs(void)
1944 {
1945         fat_cache_destroy();
1946         fat_destroy_inodecache();
1947 }
1948 
1949 module_init(init_fat_fs)
1950 module_exit(exit_fat_fs)
1951 
1952 MODULE_LICENSE("GPL");
1953 

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