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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/init.h>
 15 #include <linux/time.h>
 16 #include <linux/slab.h>
 17 #include <linux/seq_file.h>
 18 #include <linux/pagemap.h>
 19 #include <linux/mpage.h>
 20 #include <linux/buffer_head.h>
 21 #include <linux/mount.h>
 22 #include <linux/aio.h>
 23 #include <linux/vfs.h>
 24 #include <linux/parser.h>
 25 #include <linux/uio.h>
 26 #include <linux/writeback.h>
 27 #include <linux/log2.h>
 28 #include <linux/hash.h>
 29 #include <linux/blkdev.h>
 30 #include <asm/unaligned.h>
 31 #include "fat.h"
 32 
 33 #ifndef CONFIG_FAT_DEFAULT_IOCHARSET
 34 /* if user don't select VFAT, this is undefined. */
 35 #define CONFIG_FAT_DEFAULT_IOCHARSET    ""
 36 #endif
 37 
 38 static int fat_default_codepage = CONFIG_FAT_DEFAULT_CODEPAGE;
 39 static char fat_default_iocharset[] = CONFIG_FAT_DEFAULT_IOCHARSET;
 40 
 41 
 42 static int fat_add_cluster(struct inode *inode)
 43 {
 44         int err, cluster;
 45 
 46         err = fat_alloc_clusters(inode, &cluster, 1);
 47         if (err)
 48                 return err;
 49         /* FIXME: this cluster should be added after data of this
 50          * cluster is writed */
 51         err = fat_chain_add(inode, cluster, 1);
 52         if (err)
 53                 fat_free_clusters(inode, cluster);
 54         return err;
 55 }
 56 
 57 static inline int __fat_get_block(struct inode *inode, sector_t iblock,
 58                                   unsigned long *max_blocks,
 59                                   struct buffer_head *bh_result, int create)
 60 {
 61         struct super_block *sb = inode->i_sb;
 62         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 63         unsigned long mapped_blocks;
 64         sector_t phys;
 65         int err, offset;
 66 
 67         err = fat_bmap(inode, iblock, &phys, &mapped_blocks, create);
 68         if (err)
 69                 return err;
 70         if (phys) {
 71                 map_bh(bh_result, sb, phys);
 72                 *max_blocks = min(mapped_blocks, *max_blocks);
 73                 return 0;
 74         }
 75         if (!create)
 76                 return 0;
 77 
 78         if (iblock != MSDOS_I(inode)->mmu_private >> sb->s_blocksize_bits) {
 79                 fat_fs_error(sb, "corrupted file size (i_pos %lld, %lld)",
 80                         MSDOS_I(inode)->i_pos, MSDOS_I(inode)->mmu_private);
 81                 return -EIO;
 82         }
 83 
 84         offset = (unsigned long)iblock & (sbi->sec_per_clus - 1);
 85         if (!offset) {
 86                 /* TODO: multiple cluster allocation would be desirable. */
 87                 err = fat_add_cluster(inode);
 88                 if (err)
 89                         return err;
 90         }
 91         /* available blocks on this cluster */
 92         mapped_blocks = sbi->sec_per_clus - offset;
 93 
 94         *max_blocks = min(mapped_blocks, *max_blocks);
 95         MSDOS_I(inode)->mmu_private += *max_blocks << sb->s_blocksize_bits;
 96 
 97         err = fat_bmap(inode, iblock, &phys, &mapped_blocks, create);
 98         if (err)
 99                 return err;
100 
101         BUG_ON(!phys);
102         BUG_ON(*max_blocks != mapped_blocks);
103         set_buffer_new(bh_result);
104         map_bh(bh_result, sb, phys);
105 
106         return 0;
107 }
108 
109 static int fat_get_block(struct inode *inode, sector_t iblock,
110                          struct buffer_head *bh_result, int create)
111 {
112         struct super_block *sb = inode->i_sb;
113         unsigned long max_blocks = bh_result->b_size >> inode->i_blkbits;
114         int err;
115 
116         err = __fat_get_block(inode, iblock, &max_blocks, bh_result, create);
117         if (err)
118                 return err;
119         bh_result->b_size = max_blocks << sb->s_blocksize_bits;
120         return 0;
121 }
122 
123 static int fat_writepage(struct page *page, struct writeback_control *wbc)
124 {
125         return block_write_full_page(page, fat_get_block, wbc);
126 }
127 
128 static int fat_writepages(struct address_space *mapping,
129                           struct writeback_control *wbc)
130 {
131         return mpage_writepages(mapping, wbc, fat_get_block);
132 }
133 
134 static int fat_readpage(struct file *file, struct page *page)
135 {
136         return mpage_readpage(page, fat_get_block);
137 }
138 
139 static int fat_readpages(struct file *file, struct address_space *mapping,
140                          struct list_head *pages, unsigned nr_pages)
141 {
142         return mpage_readpages(mapping, pages, nr_pages, fat_get_block);
143 }
144 
145 static void fat_write_failed(struct address_space *mapping, loff_t to)
146 {
147         struct inode *inode = mapping->host;
148 
149         if (to > inode->i_size) {
150                 truncate_pagecache(inode, to, inode->i_size);
151                 fat_truncate_blocks(inode, inode->i_size);
152         }
153 }
154 
155 static int fat_write_begin(struct file *file, struct address_space *mapping,
156                         loff_t pos, unsigned len, unsigned flags,
157                         struct page **pagep, void **fsdata)
158 {
159         int err;
160 
161         *pagep = NULL;
162         err = cont_write_begin(file, mapping, pos, len, flags,
163                                 pagep, fsdata, fat_get_block,
164                                 &MSDOS_I(mapping->host)->mmu_private);
165         if (err < 0)
166                 fat_write_failed(mapping, pos + len);
167         return err;
168 }
169 
170 static int fat_write_end(struct file *file, struct address_space *mapping,
171                         loff_t pos, unsigned len, unsigned copied,
172                         struct page *pagep, void *fsdata)
173 {
174         struct inode *inode = mapping->host;
175         int err;
176         err = generic_write_end(file, mapping, pos, len, copied, pagep, fsdata);
177         if (err < len)
178                 fat_write_failed(mapping, pos + len);
179         if (!(err < 0) && !(MSDOS_I(inode)->i_attrs & ATTR_ARCH)) {
180                 inode->i_mtime = inode->i_ctime = CURRENT_TIME_SEC;
181                 MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
182                 mark_inode_dirty(inode);
183         }
184         return err;
185 }
186 
187 static ssize_t fat_direct_IO(int rw, struct kiocb *iocb,
188                              const struct iovec *iov,
189                              loff_t offset, unsigned long nr_segs)
190 {
191         struct file *file = iocb->ki_filp;
192         struct address_space *mapping = file->f_mapping;
193         struct inode *inode = mapping->host;
194         ssize_t ret;
195 
196         if (rw == WRITE) {
197                 /*
198                  * FIXME: blockdev_direct_IO() doesn't use ->write_begin(),
199                  * so we need to update the ->mmu_private to block boundary.
200                  *
201                  * But we must fill the remaining area or hole by nul for
202                  * updating ->mmu_private.
203                  *
204                  * Return 0, and fallback to normal buffered write.
205                  */
206                 loff_t size = offset + iov_length(iov, nr_segs);
207                 if (MSDOS_I(inode)->mmu_private < size)
208                         return 0;
209         }
210 
211         /*
212          * FAT need to use the DIO_LOCKING for avoiding the race
213          * condition of fat_get_block() and ->truncate().
214          */
215         ret = blockdev_direct_IO(rw, iocb, inode, iov, offset, nr_segs,
216                                  fat_get_block);
217         if (ret < 0 && (rw & WRITE))
218                 fat_write_failed(mapping, offset + iov_length(iov, nr_segs));
219 
220         return ret;
221 }
222 
223 static sector_t _fat_bmap(struct address_space *mapping, sector_t block)
224 {
225         sector_t blocknr;
226 
227         /* fat_get_cluster() assumes the requested blocknr isn't truncated. */
228         down_read(&MSDOS_I(mapping->host)->truncate_lock);
229         blocknr = generic_block_bmap(mapping, block, fat_get_block);
230         up_read(&MSDOS_I(mapping->host)->truncate_lock);
231 
232         return blocknr;
233 }
234 
235 static const struct address_space_operations fat_aops = {
236         .readpage       = fat_readpage,
237         .readpages      = fat_readpages,
238         .writepage      = fat_writepage,
239         .writepages     = fat_writepages,
240         .write_begin    = fat_write_begin,
241         .write_end      = fat_write_end,
242         .direct_IO      = fat_direct_IO,
243         .bmap           = _fat_bmap
244 };
245 
246 /*
247  * New FAT inode stuff. We do the following:
248  *      a) i_ino is constant and has nothing with on-disk location.
249  *      b) FAT manages its own cache of directory entries.
250  *      c) *This* cache is indexed by on-disk location.
251  *      d) inode has an associated directory entry, all right, but
252  *              it may be unhashed.
253  *      e) currently entries are stored within struct inode. That should
254  *              change.
255  *      f) we deal with races in the following way:
256  *              1. readdir() and lookup() do FAT-dir-cache lookup.
257  *              2. rename() unhashes the F-d-c entry and rehashes it in
258  *                      a new place.
259  *              3. unlink() and rmdir() unhash F-d-c entry.
260  *              4. fat_write_inode() checks whether the thing is unhashed.
261  *                      If it is we silently return. If it isn't we do bread(),
262  *                      check if the location is still valid and retry if it
263  *                      isn't. Otherwise we do changes.
264  *              5. Spinlock is used to protect hash/unhash/location check/lookup
265  *              6. fat_evict_inode() unhashes the F-d-c entry.
266  *              7. lookup() and readdir() do igrab() if they find a F-d-c entry
267  *                      and consider negative result as cache miss.
268  */
269 
270 static void fat_hash_init(struct super_block *sb)
271 {
272         struct msdos_sb_info *sbi = MSDOS_SB(sb);
273         int i;
274 
275         spin_lock_init(&sbi->inode_hash_lock);
276         for (i = 0; i < FAT_HASH_SIZE; i++)
277                 INIT_HLIST_HEAD(&sbi->inode_hashtable[i]);
278 }
279 
280 static inline unsigned long fat_hash(loff_t i_pos)
281 {
282         return hash_32(i_pos, FAT_HASH_BITS);
283 }
284 
285 static void dir_hash_init(struct super_block *sb)
286 {
287         struct msdos_sb_info *sbi = MSDOS_SB(sb);
288         int i;
289 
290         spin_lock_init(&sbi->dir_hash_lock);
291         for (i = 0; i < FAT_HASH_SIZE; i++)
292                 INIT_HLIST_HEAD(&sbi->dir_hashtable[i]);
293 }
294 
295 void fat_attach(struct inode *inode, loff_t i_pos)
296 {
297         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
298 
299         if (inode->i_ino != MSDOS_ROOT_INO) {
300                 struct hlist_head *head =   sbi->inode_hashtable
301                                           + fat_hash(i_pos);
302 
303                 spin_lock(&sbi->inode_hash_lock);
304                 MSDOS_I(inode)->i_pos = i_pos;
305                 hlist_add_head(&MSDOS_I(inode)->i_fat_hash, head);
306                 spin_unlock(&sbi->inode_hash_lock);
307         }
308 
309         /* If NFS support is enabled, cache the mapping of start cluster
310          * to directory inode. This is used during reconnection of
311          * dentries to the filesystem root.
312          */
313         if (S_ISDIR(inode->i_mode) && sbi->options.nfs) {
314                 struct hlist_head *d_head = sbi->dir_hashtable;
315                 d_head += fat_dir_hash(MSDOS_I(inode)->i_logstart);
316 
317                 spin_lock(&sbi->dir_hash_lock);
318                 hlist_add_head(&MSDOS_I(inode)->i_dir_hash, d_head);
319                 spin_unlock(&sbi->dir_hash_lock);
320         }
321 }
322 EXPORT_SYMBOL_GPL(fat_attach);
323 
324 void fat_detach(struct inode *inode)
325 {
326         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
327         spin_lock(&sbi->inode_hash_lock);
328         MSDOS_I(inode)->i_pos = 0;
329         hlist_del_init(&MSDOS_I(inode)->i_fat_hash);
330         spin_unlock(&sbi->inode_hash_lock);
331 
332         if (S_ISDIR(inode->i_mode) && sbi->options.nfs) {
333                 spin_lock(&sbi->dir_hash_lock);
334                 hlist_del_init(&MSDOS_I(inode)->i_dir_hash);
335                 spin_unlock(&sbi->dir_hash_lock);
336         }
337 }
338 EXPORT_SYMBOL_GPL(fat_detach);
339 
340 struct inode *fat_iget(struct super_block *sb, loff_t i_pos)
341 {
342         struct msdos_sb_info *sbi = MSDOS_SB(sb);
343         struct hlist_head *head = sbi->inode_hashtable + fat_hash(i_pos);
344         struct msdos_inode_info *i;
345         struct inode *inode = NULL;
346 
347         spin_lock(&sbi->inode_hash_lock);
348         hlist_for_each_entry(i, head, i_fat_hash) {
349                 BUG_ON(i->vfs_inode.i_sb != sb);
350                 if (i->i_pos != i_pos)
351                         continue;
352                 inode = igrab(&i->vfs_inode);
353                 if (inode)
354                         break;
355         }
356         spin_unlock(&sbi->inode_hash_lock);
357         return inode;
358 }
359 
360 static int is_exec(unsigned char *extension)
361 {
362         unsigned char *exe_extensions = "EXECOMBAT", *walk;
363 
364         for (walk = exe_extensions; *walk; walk += 3)
365                 if (!strncmp(extension, walk, 3))
366                         return 1;
367         return 0;
368 }
369 
370 static int fat_calc_dir_size(struct inode *inode)
371 {
372         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
373         int ret, fclus, dclus;
374 
375         inode->i_size = 0;
376         if (MSDOS_I(inode)->i_start == 0)
377                 return 0;
378 
379         ret = fat_get_cluster(inode, FAT_ENT_EOF, &fclus, &dclus);
380         if (ret < 0)
381                 return ret;
382         inode->i_size = (fclus + 1) << sbi->cluster_bits;
383 
384         return 0;
385 }
386 
387 /* doesn't deal with root inode */
388 int fat_fill_inode(struct inode *inode, struct msdos_dir_entry *de)
389 {
390         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
391         int error;
392 
393         MSDOS_I(inode)->i_pos = 0;
394         inode->i_uid = sbi->options.fs_uid;
395         inode->i_gid = sbi->options.fs_gid;
396         inode->i_version++;
397         inode->i_generation = get_seconds();
398 
399         if ((de->attr & ATTR_DIR) && !IS_FREE(de->name)) {
400                 inode->i_generation &= ~1;
401                 inode->i_mode = fat_make_mode(sbi, de->attr, S_IRWXUGO);
402                 inode->i_op = sbi->dir_ops;
403                 inode->i_fop = &fat_dir_operations;
404 
405                 MSDOS_I(inode)->i_start = fat_get_start(sbi, de);
406                 MSDOS_I(inode)->i_logstart = MSDOS_I(inode)->i_start;
407                 error = fat_calc_dir_size(inode);
408                 if (error < 0)
409                         return error;
410                 MSDOS_I(inode)->mmu_private = inode->i_size;
411 
412                 set_nlink(inode, fat_subdirs(inode));
413         } else { /* not a directory */
414                 inode->i_generation |= 1;
415                 inode->i_mode = fat_make_mode(sbi, de->attr,
416                         ((sbi->options.showexec && !is_exec(de->name + 8))
417                          ? S_IRUGO|S_IWUGO : S_IRWXUGO));
418                 MSDOS_I(inode)->i_start = fat_get_start(sbi, de);
419 
420                 MSDOS_I(inode)->i_logstart = MSDOS_I(inode)->i_start;
421                 inode->i_size = le32_to_cpu(de->size);
422                 inode->i_op = &fat_file_inode_operations;
423                 inode->i_fop = &fat_file_operations;
424                 inode->i_mapping->a_ops = &fat_aops;
425                 MSDOS_I(inode)->mmu_private = inode->i_size;
426         }
427         if (de->attr & ATTR_SYS) {
428                 if (sbi->options.sys_immutable)
429                         inode->i_flags |= S_IMMUTABLE;
430         }
431         fat_save_attrs(inode, de->attr);
432 
433         inode->i_blocks = ((inode->i_size + (sbi->cluster_size - 1))
434                            & ~((loff_t)sbi->cluster_size - 1)) >> 9;
435 
436         fat_time_fat2unix(sbi, &inode->i_mtime, de->time, de->date, 0);
437         if (sbi->options.isvfat) {
438                 fat_time_fat2unix(sbi, &inode->i_ctime, de->ctime,
439                                   de->cdate, de->ctime_cs);
440                 fat_time_fat2unix(sbi, &inode->i_atime, 0, de->adate, 0);
441         } else
442                 inode->i_ctime = inode->i_atime = inode->i_mtime;
443 
444         return 0;
445 }
446 
447 static inline void fat_lock_build_inode(struct msdos_sb_info *sbi)
448 {
449         if (sbi->options.nfs == FAT_NFS_NOSTALE_RO)
450                 mutex_lock(&sbi->nfs_build_inode_lock);
451 }
452 
453 static inline void fat_unlock_build_inode(struct msdos_sb_info *sbi)
454 {
455         if (sbi->options.nfs == FAT_NFS_NOSTALE_RO)
456                 mutex_unlock(&sbi->nfs_build_inode_lock);
457 }
458 
459 struct inode *fat_build_inode(struct super_block *sb,
460                         struct msdos_dir_entry *de, loff_t i_pos)
461 {
462         struct inode *inode;
463         int err;
464 
465         fat_lock_build_inode(MSDOS_SB(sb));
466         inode = fat_iget(sb, i_pos);
467         if (inode)
468                 goto out;
469         inode = new_inode(sb);
470         if (!inode) {
471                 inode = ERR_PTR(-ENOMEM);
472                 goto out;
473         }
474         inode->i_ino = iunique(sb, MSDOS_ROOT_INO);
475         inode->i_version = 1;
476         err = fat_fill_inode(inode, de);
477         if (err) {
478                 iput(inode);
479                 inode = ERR_PTR(err);
480                 goto out;
481         }
482         fat_attach(inode, i_pos);
483         insert_inode_hash(inode);
484 out:
485         fat_unlock_build_inode(MSDOS_SB(sb));
486         return inode;
487 }
488 
489 EXPORT_SYMBOL_GPL(fat_build_inode);
490 
491 static void fat_evict_inode(struct inode *inode)
492 {
493         truncate_inode_pages(&inode->i_data, 0);
494         if (!inode->i_nlink) {
495                 inode->i_size = 0;
496                 fat_truncate_blocks(inode, 0);
497         }
498         invalidate_inode_buffers(inode);
499         clear_inode(inode);
500         fat_cache_inval_inode(inode);
501         fat_detach(inode);
502 }
503 
504 static void fat_set_state(struct super_block *sb,
505                         unsigned int set, unsigned int force)
506 {
507         struct buffer_head *bh;
508         struct fat_boot_sector *b;
509         struct msdos_sb_info *sbi = sb->s_fs_info;
510 
511         /* do not change any thing if mounted read only */
512         if ((sb->s_flags & MS_RDONLY) && !force)
513                 return;
514 
515         /* do not change state if fs was dirty */
516         if (sbi->dirty) {
517                 /* warn only on set (mount). */
518                 if (set)
519                         fat_msg(sb, KERN_WARNING, "Volume was not properly "
520                                 "unmounted. Some data may be corrupt. "
521                                 "Please run fsck.");
522                 return;
523         }
524 
525         bh = sb_bread(sb, 0);
526         if (bh == NULL) {
527                 fat_msg(sb, KERN_ERR, "unable to read boot sector "
528                         "to mark fs as dirty");
529                 return;
530         }
531 
532         b = (struct fat_boot_sector *) bh->b_data;
533 
534         if (sbi->fat_bits == 32) {
535                 if (set)
536                         b->fat32.state |= FAT_STATE_DIRTY;
537                 else
538                         b->fat32.state &= ~FAT_STATE_DIRTY;
539         } else /* fat 16 and 12 */ {
540                 if (set)
541                         b->fat16.state |= FAT_STATE_DIRTY;
542                 else
543                         b->fat16.state &= ~FAT_STATE_DIRTY;
544         }
545 
546         mark_buffer_dirty(bh);
547         sync_dirty_buffer(bh);
548         brelse(bh);
549 }
550 
551 static void fat_put_super(struct super_block *sb)
552 {
553         struct msdos_sb_info *sbi = MSDOS_SB(sb);
554 
555         fat_set_state(sb, 0, 0);
556 
557         iput(sbi->fsinfo_inode);
558         iput(sbi->fat_inode);
559 
560         unload_nls(sbi->nls_disk);
561         unload_nls(sbi->nls_io);
562 
563         if (sbi->options.iocharset != fat_default_iocharset)
564                 kfree(sbi->options.iocharset);
565 
566         sb->s_fs_info = NULL;
567         kfree(sbi);
568 }
569 
570 static struct kmem_cache *fat_inode_cachep;
571 
572 static struct inode *fat_alloc_inode(struct super_block *sb)
573 {
574         struct msdos_inode_info *ei;
575         ei = kmem_cache_alloc(fat_inode_cachep, GFP_NOFS);
576         if (!ei)
577                 return NULL;
578 
579         init_rwsem(&ei->truncate_lock);
580         return &ei->vfs_inode;
581 }
582 
583 static void fat_i_callback(struct rcu_head *head)
584 {
585         struct inode *inode = container_of(head, struct inode, i_rcu);
586         kmem_cache_free(fat_inode_cachep, MSDOS_I(inode));
587 }
588 
589 static void fat_destroy_inode(struct inode *inode)
590 {
591         call_rcu(&inode->i_rcu, fat_i_callback);
592 }
593 
594 static void init_once(void *foo)
595 {
596         struct msdos_inode_info *ei = (struct msdos_inode_info *)foo;
597 
598         spin_lock_init(&ei->cache_lru_lock);
599         ei->nr_caches = 0;
600         ei->cache_valid_id = FAT_CACHE_VALID + 1;
601         INIT_LIST_HEAD(&ei->cache_lru);
602         INIT_HLIST_NODE(&ei->i_fat_hash);
603         INIT_HLIST_NODE(&ei->i_dir_hash);
604         inode_init_once(&ei->vfs_inode);
605 }
606 
607 static int __init fat_init_inodecache(void)
608 {
609         fat_inode_cachep = kmem_cache_create("fat_inode_cache",
610                                              sizeof(struct msdos_inode_info),
611                                              0, (SLAB_RECLAIM_ACCOUNT|
612                                                 SLAB_MEM_SPREAD),
613                                              init_once);
614         if (fat_inode_cachep == NULL)
615                 return -ENOMEM;
616         return 0;
617 }
618 
619 static void __exit fat_destroy_inodecache(void)
620 {
621         /*
622          * Make sure all delayed rcu free inodes are flushed before we
623          * destroy cache.
624          */
625         rcu_barrier();
626         kmem_cache_destroy(fat_inode_cachep);
627 }
628 
629 static int fat_remount(struct super_block *sb, int *flags, char *data)
630 {
631         int new_rdonly;
632         struct msdos_sb_info *sbi = MSDOS_SB(sb);
633         *flags |= MS_NODIRATIME | (sbi->options.isvfat ? 0 : MS_NOATIME);
634 
635         /* make sure we update state on remount. */
636         new_rdonly = *flags & MS_RDONLY;
637         if (new_rdonly != (sb->s_flags & MS_RDONLY)) {
638                 if (new_rdonly)
639                         fat_set_state(sb, 0, 0);
640                 else
641                         fat_set_state(sb, 1, 1);
642         }
643         return 0;
644 }
645 
646 static int fat_statfs(struct dentry *dentry, struct kstatfs *buf)
647 {
648         struct super_block *sb = dentry->d_sb;
649         struct msdos_sb_info *sbi = MSDOS_SB(sb);
650         u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
651 
652         /* If the count of free cluster is still unknown, counts it here. */
653         if (sbi->free_clusters == -1 || !sbi->free_clus_valid) {
654                 int err = fat_count_free_clusters(dentry->d_sb);
655                 if (err)
656                         return err;
657         }
658 
659         buf->f_type = dentry->d_sb->s_magic;
660         buf->f_bsize = sbi->cluster_size;
661         buf->f_blocks = sbi->max_cluster - FAT_START_ENT;
662         buf->f_bfree = sbi->free_clusters;
663         buf->f_bavail = sbi->free_clusters;
664         buf->f_fsid.val[0] = (u32)id;
665         buf->f_fsid.val[1] = (u32)(id >> 32);
666         buf->f_namelen =
667                 (sbi->options.isvfat ? FAT_LFN_LEN : 12) * NLS_MAX_CHARSET_SIZE;
668 
669         return 0;
670 }
671 
672 static int __fat_write_inode(struct inode *inode, int wait)
673 {
674         struct super_block *sb = inode->i_sb;
675         struct msdos_sb_info *sbi = MSDOS_SB(sb);
676         struct buffer_head *bh;
677         struct msdos_dir_entry *raw_entry;
678         loff_t i_pos;
679         sector_t blocknr;
680         int err, offset;
681 
682         if (inode->i_ino == MSDOS_ROOT_INO)
683                 return 0;
684 
685 retry:
686         i_pos = fat_i_pos_read(sbi, inode);
687         if (!i_pos)
688                 return 0;
689 
690         fat_get_blknr_offset(sbi, i_pos, &blocknr, &offset);
691         bh = sb_bread(sb, blocknr);
692         if (!bh) {
693                 fat_msg(sb, KERN_ERR, "unable to read inode block "
694                        "for updating (i_pos %lld)", i_pos);
695                 return -EIO;
696         }
697         spin_lock(&sbi->inode_hash_lock);
698         if (i_pos != MSDOS_I(inode)->i_pos) {
699                 spin_unlock(&sbi->inode_hash_lock);
700                 brelse(bh);
701                 goto retry;
702         }
703 
704         raw_entry = &((struct msdos_dir_entry *) (bh->b_data))[offset];
705         if (S_ISDIR(inode->i_mode))
706                 raw_entry->size = 0;
707         else
708                 raw_entry->size = cpu_to_le32(inode->i_size);
709         raw_entry->attr = fat_make_attrs(inode);
710         fat_set_start(raw_entry, MSDOS_I(inode)->i_logstart);
711         fat_time_unix2fat(sbi, &inode->i_mtime, &raw_entry->time,
712                           &raw_entry->date, NULL);
713         if (sbi->options.isvfat) {
714                 __le16 atime;
715                 fat_time_unix2fat(sbi, &inode->i_ctime, &raw_entry->ctime,
716                                   &raw_entry->cdate, &raw_entry->ctime_cs);
717                 fat_time_unix2fat(sbi, &inode->i_atime, &atime,
718                                   &raw_entry->adate, NULL);
719         }
720         spin_unlock(&sbi->inode_hash_lock);
721         mark_buffer_dirty(bh);
722         err = 0;
723         if (wait)
724                 err = sync_dirty_buffer(bh);
725         brelse(bh);
726         return err;
727 }
728 
729 static int fat_write_inode(struct inode *inode, struct writeback_control *wbc)
730 {
731         int err;
732 
733         if (inode->i_ino == MSDOS_FSINFO_INO) {
734                 struct super_block *sb = inode->i_sb;
735 
736                 mutex_lock(&MSDOS_SB(sb)->s_lock);
737                 err = fat_clusters_flush(sb);
738                 mutex_unlock(&MSDOS_SB(sb)->s_lock);
739         } else
740                 err = __fat_write_inode(inode, wbc->sync_mode == WB_SYNC_ALL);
741 
742         return err;
743 }
744 
745 int fat_sync_inode(struct inode *inode)
746 {
747         return __fat_write_inode(inode, 1);
748 }
749 
750 EXPORT_SYMBOL_GPL(fat_sync_inode);
751 
752 static int fat_show_options(struct seq_file *m, struct dentry *root);
753 static const struct super_operations fat_sops = {
754         .alloc_inode    = fat_alloc_inode,
755         .destroy_inode  = fat_destroy_inode,
756         .write_inode    = fat_write_inode,
757         .evict_inode    = fat_evict_inode,
758         .put_super      = fat_put_super,
759         .statfs         = fat_statfs,
760         .remount_fs     = fat_remount,
761 
762         .show_options   = fat_show_options,
763 };
764 
765 static int fat_show_options(struct seq_file *m, struct dentry *root)
766 {
767         struct msdos_sb_info *sbi = MSDOS_SB(root->d_sb);
768         struct fat_mount_options *opts = &sbi->options;
769         int isvfat = opts->isvfat;
770 
771         if (!uid_eq(opts->fs_uid, GLOBAL_ROOT_UID))
772                 seq_printf(m, ",uid=%u",
773                                 from_kuid_munged(&init_user_ns, opts->fs_uid));
774         if (!gid_eq(opts->fs_gid, GLOBAL_ROOT_GID))
775                 seq_printf(m, ",gid=%u",
776                                 from_kgid_munged(&init_user_ns, opts->fs_gid));
777         seq_printf(m, ",fmask=%04o", opts->fs_fmask);
778         seq_printf(m, ",dmask=%04o", opts->fs_dmask);
779         if (opts->allow_utime)
780                 seq_printf(m, ",allow_utime=%04o", opts->allow_utime);
781         if (sbi->nls_disk)
782                 /* strip "cp" prefix from displayed option */
783                 seq_printf(m, ",codepage=%s", &sbi->nls_disk->charset[2]);
784         if (isvfat) {
785                 if (sbi->nls_io)
786                         seq_printf(m, ",iocharset=%s", sbi->nls_io->charset);
787 
788                 switch (opts->shortname) {
789                 case VFAT_SFN_DISPLAY_WIN95 | VFAT_SFN_CREATE_WIN95:
790                         seq_puts(m, ",shortname=win95");
791                         break;
792                 case VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WINNT:
793                         seq_puts(m, ",shortname=winnt");
794                         break;
795                 case VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WIN95:
796                         seq_puts(m, ",shortname=mixed");
797                         break;
798                 case VFAT_SFN_DISPLAY_LOWER | VFAT_SFN_CREATE_WIN95:
799                         seq_puts(m, ",shortname=lower");
800                         break;
801                 default:
802                         seq_puts(m, ",shortname=unknown");
803                         break;
804                 }
805         }
806         if (opts->name_check != 'n')
807                 seq_printf(m, ",check=%c", opts->name_check);
808         if (opts->usefree)
809                 seq_puts(m, ",usefree");
810         if (opts->quiet)
811                 seq_puts(m, ",quiet");
812         if (opts->showexec)
813                 seq_puts(m, ",showexec");
814         if (opts->sys_immutable)
815                 seq_puts(m, ",sys_immutable");
816         if (!isvfat) {
817                 if (opts->dotsOK)
818                         seq_puts(m, ",dotsOK=yes");
819                 if (opts->nocase)
820                         seq_puts(m, ",nocase");
821         } else {
822                 if (opts->utf8)
823                         seq_puts(m, ",utf8");
824                 if (opts->unicode_xlate)
825                         seq_puts(m, ",uni_xlate");
826                 if (!opts->numtail)
827                         seq_puts(m, ",nonumtail");
828                 if (opts->rodir)
829                         seq_puts(m, ",rodir");
830         }
831         if (opts->flush)
832                 seq_puts(m, ",flush");
833         if (opts->tz_set) {
834                 if (opts->time_offset)
835                         seq_printf(m, ",time_offset=%d", opts->time_offset);
836                 else
837                         seq_puts(m, ",tz=UTC");
838         }
839         if (opts->errors == FAT_ERRORS_CONT)
840                 seq_puts(m, ",errors=continue");
841         else if (opts->errors == FAT_ERRORS_PANIC)
842                 seq_puts(m, ",errors=panic");
843         else
844                 seq_puts(m, ",errors=remount-ro");
845         if (opts->nfs == FAT_NFS_NOSTALE_RO)
846                 seq_puts(m, ",nfs=nostale_ro");
847         else if (opts->nfs)
848                 seq_puts(m, ",nfs=stale_rw");
849         if (opts->discard)
850                 seq_puts(m, ",discard");
851 
852         return 0;
853 }
854 
855 enum {
856         Opt_check_n, Opt_check_r, Opt_check_s, Opt_uid, Opt_gid,
857         Opt_umask, Opt_dmask, Opt_fmask, Opt_allow_utime, Opt_codepage,
858         Opt_usefree, Opt_nocase, Opt_quiet, Opt_showexec, Opt_debug,
859         Opt_immutable, Opt_dots, Opt_nodots,
860         Opt_charset, Opt_shortname_lower, Opt_shortname_win95,
861         Opt_shortname_winnt, Opt_shortname_mixed, Opt_utf8_no, Opt_utf8_yes,
862         Opt_uni_xl_no, Opt_uni_xl_yes, Opt_nonumtail_no, Opt_nonumtail_yes,
863         Opt_obsolete, Opt_flush, Opt_tz_utc, Opt_rodir, Opt_err_cont,
864         Opt_err_panic, Opt_err_ro, Opt_discard, Opt_nfs, Opt_time_offset,
865         Opt_nfs_stale_rw, Opt_nfs_nostale_ro, Opt_err,
866 };
867 
868 static const match_table_t fat_tokens = {
869         {Opt_check_r, "check=relaxed"},
870         {Opt_check_s, "check=strict"},
871         {Opt_check_n, "check=normal"},
872         {Opt_check_r, "check=r"},
873         {Opt_check_s, "check=s"},
874         {Opt_check_n, "check=n"},
875         {Opt_uid, "uid=%u"},
876         {Opt_gid, "gid=%u"},
877         {Opt_umask, "umask=%o"},
878         {Opt_dmask, "dmask=%o"},
879         {Opt_fmask, "fmask=%o"},
880         {Opt_allow_utime, "allow_utime=%o"},
881         {Opt_codepage, "codepage=%u"},
882         {Opt_usefree, "usefree"},
883         {Opt_nocase, "nocase"},
884         {Opt_quiet, "quiet"},
885         {Opt_showexec, "showexec"},
886         {Opt_debug, "debug"},
887         {Opt_immutable, "sys_immutable"},
888         {Opt_flush, "flush"},
889         {Opt_tz_utc, "tz=UTC"},
890         {Opt_time_offset, "time_offset=%d"},
891         {Opt_err_cont, "errors=continue"},
892         {Opt_err_panic, "errors=panic"},
893         {Opt_err_ro, "errors=remount-ro"},
894         {Opt_discard, "discard"},
895         {Opt_nfs_stale_rw, "nfs"},
896         {Opt_nfs_stale_rw, "nfs=stale_rw"},
897         {Opt_nfs_nostale_ro, "nfs=nostale_ro"},
898         {Opt_obsolete, "conv=binary"},
899         {Opt_obsolete, "conv=text"},
900         {Opt_obsolete, "conv=auto"},
901         {Opt_obsolete, "conv=b"},
902         {Opt_obsolete, "conv=t"},
903         {Opt_obsolete, "conv=a"},
904         {Opt_obsolete, "fat=%u"},
905         {Opt_obsolete, "blocksize=%u"},
906         {Opt_obsolete, "cvf_format=%20s"},
907         {Opt_obsolete, "cvf_options=%100s"},
908         {Opt_obsolete, "posix"},
909         {Opt_err, NULL},
910 };
911 static const match_table_t msdos_tokens = {
912         {Opt_nodots, "nodots"},
913         {Opt_nodots, "dotsOK=no"},
914         {Opt_dots, "dots"},
915         {Opt_dots, "dotsOK=yes"},
916         {Opt_err, NULL}
917 };
918 static const match_table_t vfat_tokens = {
919         {Opt_charset, "iocharset=%s"},
920         {Opt_shortname_lower, "shortname=lower"},
921         {Opt_shortname_win95, "shortname=win95"},
922         {Opt_shortname_winnt, "shortname=winnt"},
923         {Opt_shortname_mixed, "shortname=mixed"},
924         {Opt_utf8_no, "utf8=0"},                /* 0 or no or false */
925         {Opt_utf8_no, "utf8=no"},
926         {Opt_utf8_no, "utf8=false"},
927         {Opt_utf8_yes, "utf8=1"},               /* empty or 1 or yes or true */
928         {Opt_utf8_yes, "utf8=yes"},
929         {Opt_utf8_yes, "utf8=true"},
930         {Opt_utf8_yes, "utf8"},
931         {Opt_uni_xl_no, "uni_xlate=0"},         /* 0 or no or false */
932         {Opt_uni_xl_no, "uni_xlate=no"},
933         {Opt_uni_xl_no, "uni_xlate=false"},
934         {Opt_uni_xl_yes, "uni_xlate=1"},        /* empty or 1 or yes or true */
935         {Opt_uni_xl_yes, "uni_xlate=yes"},
936         {Opt_uni_xl_yes, "uni_xlate=true"},
937         {Opt_uni_xl_yes, "uni_xlate"},
938         {Opt_nonumtail_no, "nonumtail=0"},      /* 0 or no or false */
939         {Opt_nonumtail_no, "nonumtail=no"},
940         {Opt_nonumtail_no, "nonumtail=false"},
941         {Opt_nonumtail_yes, "nonumtail=1"},     /* empty or 1 or yes or true */
942         {Opt_nonumtail_yes, "nonumtail=yes"},
943         {Opt_nonumtail_yes, "nonumtail=true"},
944         {Opt_nonumtail_yes, "nonumtail"},
945         {Opt_rodir, "rodir"},
946         {Opt_err, NULL}
947 };
948 
949 static int parse_options(struct super_block *sb, char *options, int is_vfat,
950                          int silent, int *debug, struct fat_mount_options *opts)
951 {
952         char *p;
953         substring_t args[MAX_OPT_ARGS];
954         int option;
955         char *iocharset;
956 
957         opts->isvfat = is_vfat;
958 
959         opts->fs_uid = current_uid();
960         opts->fs_gid = current_gid();
961         opts->fs_fmask = opts->fs_dmask = current_umask();
962         opts->allow_utime = -1;
963         opts->codepage = fat_default_codepage;
964         opts->iocharset = fat_default_iocharset;
965         if (is_vfat) {
966                 opts->shortname = VFAT_SFN_DISPLAY_WINNT|VFAT_SFN_CREATE_WIN95;
967                 opts->rodir = 0;
968         } else {
969                 opts->shortname = 0;
970                 opts->rodir = 1;
971         }
972         opts->name_check = 'n';
973         opts->quiet = opts->showexec = opts->sys_immutable = opts->dotsOK =  0;
974         opts->utf8 = opts->unicode_xlate = 0;
975         opts->numtail = 1;
976         opts->usefree = opts->nocase = 0;
977         opts->tz_set = 0;
978         opts->nfs = 0;
979         opts->errors = FAT_ERRORS_RO;
980         *debug = 0;
981 
982         if (!options)
983                 goto out;
984 
985         while ((p = strsep(&options, ",")) != NULL) {
986                 int token;
987                 if (!*p)
988                         continue;
989 
990                 token = match_token(p, fat_tokens, args);
991                 if (token == Opt_err) {
992                         if (is_vfat)
993                                 token = match_token(p, vfat_tokens, args);
994                         else
995                                 token = match_token(p, msdos_tokens, args);
996                 }
997                 switch (token) {
998                 case Opt_check_s:
999                         opts->name_check = 's';
1000                         break;
1001                 case Opt_check_r:
1002                         opts->name_check = 'r';
1003                         break;
1004                 case Opt_check_n:
1005                         opts->name_check = 'n';
1006                         break;
1007                 case Opt_usefree:
1008                         opts->usefree = 1;
1009                         break;
1010                 case Opt_nocase:
1011                         if (!is_vfat)
1012                                 opts->nocase = 1;
1013                         else {
1014                                 /* for backward compatibility */
1015                                 opts->shortname = VFAT_SFN_DISPLAY_WIN95
1016                                         | VFAT_SFN_CREATE_WIN95;
1017                         }
1018                         break;
1019                 case Opt_quiet:
1020                         opts->quiet = 1;
1021                         break;
1022                 case Opt_showexec:
1023                         opts->showexec = 1;
1024                         break;
1025                 case Opt_debug:
1026                         *debug = 1;
1027                         break;
1028                 case Opt_immutable:
1029                         opts->sys_immutable = 1;
1030                         break;
1031                 case Opt_uid:
1032                         if (match_int(&args[0], &option))
1033                                 return -EINVAL;
1034                         opts->fs_uid = make_kuid(current_user_ns(), option);
1035                         if (!uid_valid(opts->fs_uid))
1036                                 return -EINVAL;
1037                         break;
1038                 case Opt_gid:
1039                         if (match_int(&args[0], &option))
1040                                 return -EINVAL;
1041                         opts->fs_gid = make_kgid(current_user_ns(), option);
1042                         if (!gid_valid(opts->fs_gid))
1043                                 return -EINVAL;
1044                         break;
1045                 case Opt_umask:
1046                         if (match_octal(&args[0], &option))
1047                                 return -EINVAL;
1048                         opts->fs_fmask = opts->fs_dmask = option;
1049                         break;
1050                 case Opt_dmask:
1051                         if (match_octal(&args[0], &option))
1052                                 return -EINVAL;
1053                         opts->fs_dmask = option;
1054                         break;
1055                 case Opt_fmask:
1056                         if (match_octal(&args[0], &option))
1057                                 return -EINVAL;
1058                         opts->fs_fmask = option;
1059                         break;
1060                 case Opt_allow_utime:
1061                         if (match_octal(&args[0], &option))
1062                                 return -EINVAL;
1063                         opts->allow_utime = option & (S_IWGRP | S_IWOTH);
1064                         break;
1065                 case Opt_codepage:
1066                         if (match_int(&args[0], &option))
1067                                 return -EINVAL;
1068                         opts->codepage = option;
1069                         break;
1070                 case Opt_flush:
1071                         opts->flush = 1;
1072                         break;
1073                 case Opt_time_offset:
1074                         if (match_int(&args[0], &option))
1075                                 return -EINVAL;
1076                         if (option < -12 * 60 || option > 12 * 60)
1077                                 return -EINVAL;
1078                         opts->tz_set = 1;
1079                         opts->time_offset = option;
1080                         break;
1081                 case Opt_tz_utc:
1082                         opts->tz_set = 1;
1083                         opts->time_offset = 0;
1084                         break;
1085                 case Opt_err_cont:
1086                         opts->errors = FAT_ERRORS_CONT;
1087                         break;
1088                 case Opt_err_panic:
1089                         opts->errors = FAT_ERRORS_PANIC;
1090                         break;
1091                 case Opt_err_ro:
1092                         opts->errors = FAT_ERRORS_RO;
1093                         break;
1094                 case Opt_nfs_stale_rw:
1095                         opts->nfs = FAT_NFS_STALE_RW;
1096                         break;
1097                 case Opt_nfs_nostale_ro:
1098                         opts->nfs = FAT_NFS_NOSTALE_RO;
1099                         break;
1100 
1101                 /* msdos specific */
1102                 case Opt_dots:
1103                         opts->dotsOK = 1;
1104                         break;
1105                 case Opt_nodots:
1106                         opts->dotsOK = 0;
1107                         break;
1108 
1109                 /* vfat specific */
1110                 case Opt_charset:
1111                         if (opts->iocharset != fat_default_iocharset)
1112                                 kfree(opts->iocharset);
1113                         iocharset = match_strdup(&args[0]);
1114                         if (!iocharset)
1115                                 return -ENOMEM;
1116                         opts->iocharset = iocharset;
1117                         break;
1118                 case Opt_shortname_lower:
1119                         opts->shortname = VFAT_SFN_DISPLAY_LOWER
1120                                         | VFAT_SFN_CREATE_WIN95;
1121                         break;
1122                 case Opt_shortname_win95:
1123                         opts->shortname = VFAT_SFN_DISPLAY_WIN95
1124                                         | VFAT_SFN_CREATE_WIN95;
1125                         break;
1126                 case Opt_shortname_winnt:
1127                         opts->shortname = VFAT_SFN_DISPLAY_WINNT
1128                                         | VFAT_SFN_CREATE_WINNT;
1129                         break;
1130                 case Opt_shortname_mixed:
1131                         opts->shortname = VFAT_SFN_DISPLAY_WINNT
1132                                         | VFAT_SFN_CREATE_WIN95;
1133                         break;
1134                 case Opt_utf8_no:               /* 0 or no or false */
1135                         opts->utf8 = 0;
1136                         break;
1137                 case Opt_utf8_yes:              /* empty or 1 or yes or true */
1138                         opts->utf8 = 1;
1139                         break;
1140                 case Opt_uni_xl_no:             /* 0 or no or false */
1141                         opts->unicode_xlate = 0;
1142                         break;
1143                 case Opt_uni_xl_yes:            /* empty or 1 or yes or true */
1144                         opts->unicode_xlate = 1;
1145                         break;
1146                 case Opt_nonumtail_no:          /* 0 or no or false */
1147                         opts->numtail = 1;      /* negated option */
1148                         break;
1149                 case Opt_nonumtail_yes:         /* empty or 1 or yes or true */
1150                         opts->numtail = 0;      /* negated option */
1151                         break;
1152                 case Opt_rodir:
1153                         opts->rodir = 1;
1154                         break;
1155                 case Opt_discard:
1156                         opts->discard = 1;
1157                         break;
1158 
1159                 /* obsolete mount options */
1160                 case Opt_obsolete:
1161                         fat_msg(sb, KERN_INFO, "\"%s\" option is obsolete, "
1162                                "not supported now", p);
1163                         break;
1164                 /* unknown option */
1165                 default:
1166                         if (!silent) {
1167                                 fat_msg(sb, KERN_ERR,
1168                                        "Unrecognized mount option \"%s\" "
1169                                        "or missing value", p);
1170                         }
1171                         return -EINVAL;
1172                 }
1173         }
1174 
1175 out:
1176         /* UTF-8 doesn't provide FAT semantics */
1177         if (!strcmp(opts->iocharset, "utf8")) {
1178                 fat_msg(sb, KERN_WARNING, "utf8 is not a recommended IO charset"
1179                        " for FAT filesystems, filesystem will be "
1180                        "case sensitive!");
1181         }
1182 
1183         /* If user doesn't specify allow_utime, it's initialized from dmask. */
1184         if (opts->allow_utime == (unsigned short)-1)
1185                 opts->allow_utime = ~opts->fs_dmask & (S_IWGRP | S_IWOTH);
1186         if (opts->unicode_xlate)
1187                 opts->utf8 = 0;
1188         if (opts->nfs == FAT_NFS_NOSTALE_RO) {
1189                 sb->s_flags |= MS_RDONLY;
1190                 sb->s_export_op = &fat_export_ops_nostale;
1191         }
1192 
1193         return 0;
1194 }
1195 
1196 static int fat_read_root(struct inode *inode)
1197 {
1198         struct super_block *sb = inode->i_sb;
1199         struct msdos_sb_info *sbi = MSDOS_SB(sb);
1200         int error;
1201 
1202         MSDOS_I(inode)->i_pos = MSDOS_ROOT_INO;
1203         inode->i_uid = sbi->options.fs_uid;
1204         inode->i_gid = sbi->options.fs_gid;
1205         inode->i_version++;
1206         inode->i_generation = 0;
1207         inode->i_mode = fat_make_mode(sbi, ATTR_DIR, S_IRWXUGO);
1208         inode->i_op = sbi->dir_ops;
1209         inode->i_fop = &fat_dir_operations;
1210         if (sbi->fat_bits == 32) {
1211                 MSDOS_I(inode)->i_start = sbi->root_cluster;
1212                 error = fat_calc_dir_size(inode);
1213                 if (error < 0)
1214                         return error;
1215         } else {
1216                 MSDOS_I(inode)->i_start = 0;
1217                 inode->i_size = sbi->dir_entries * sizeof(struct msdos_dir_entry);
1218         }
1219         inode->i_blocks = ((inode->i_size + (sbi->cluster_size - 1))
1220                            & ~((loff_t)sbi->cluster_size - 1)) >> 9;
1221         MSDOS_I(inode)->i_logstart = 0;
1222         MSDOS_I(inode)->mmu_private = inode->i_size;
1223 
1224         fat_save_attrs(inode, ATTR_DIR);
1225         inode->i_mtime.tv_sec = inode->i_atime.tv_sec = inode->i_ctime.tv_sec = 0;
1226         inode->i_mtime.tv_nsec = inode->i_atime.tv_nsec = inode->i_ctime.tv_nsec = 0;
1227         set_nlink(inode, fat_subdirs(inode)+2);
1228 
1229         return 0;
1230 }
1231 
1232 static unsigned long calc_fat_clusters(struct super_block *sb)
1233 {
1234         struct msdos_sb_info *sbi = MSDOS_SB(sb);
1235 
1236         /* Divide first to avoid overflow */
1237         if (sbi->fat_bits != 12) {
1238                 unsigned long ent_per_sec = sb->s_blocksize * 8 / sbi->fat_bits;
1239                 return ent_per_sec * sbi->fat_length;
1240         }
1241 
1242         return sbi->fat_length * sb->s_blocksize * 8 / sbi->fat_bits;
1243 }
1244 
1245 /*
1246  * Read the super block of an MS-DOS FS.
1247  */
1248 int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat,
1249                    void (*setup)(struct super_block *))
1250 {
1251         struct inode *root_inode = NULL, *fat_inode = NULL;
1252         struct inode *fsinfo_inode = NULL;
1253         struct buffer_head *bh;
1254         struct fat_boot_sector *b;
1255         struct msdos_sb_info *sbi;
1256         u16 logical_sector_size;
1257         u32 total_sectors, total_clusters, fat_clusters, rootdir_sectors;
1258         int debug;
1259         unsigned int media;
1260         long error;
1261         char buf[50];
1262 
1263         /*
1264          * GFP_KERNEL is ok here, because while we do hold the
1265          * supeblock lock, memory pressure can't call back into
1266          * the filesystem, since we're only just about to mount
1267          * it and have no inodes etc active!
1268          */
1269         sbi = kzalloc(sizeof(struct msdos_sb_info), GFP_KERNEL);
1270         if (!sbi)
1271                 return -ENOMEM;
1272         sb->s_fs_info = sbi;
1273 
1274         sb->s_flags |= MS_NODIRATIME;
1275         sb->s_magic = MSDOS_SUPER_MAGIC;
1276         sb->s_op = &fat_sops;
1277         sb->s_export_op = &fat_export_ops;
1278         mutex_init(&sbi->nfs_build_inode_lock);
1279         ratelimit_state_init(&sbi->ratelimit, DEFAULT_RATELIMIT_INTERVAL,
1280                              DEFAULT_RATELIMIT_BURST);
1281 
1282         error = parse_options(sb, data, isvfat, silent, &debug, &sbi->options);
1283         if (error)
1284                 goto out_fail;
1285 
1286         setup(sb); /* flavour-specific stuff that needs options */
1287 
1288         error = -EIO;
1289         sb_min_blocksize(sb, 512);
1290         bh = sb_bread(sb, 0);
1291         if (bh == NULL) {
1292                 fat_msg(sb, KERN_ERR, "unable to read boot sector");
1293                 goto out_fail;
1294         }
1295 
1296         b = (struct fat_boot_sector *) bh->b_data;
1297         if (!b->reserved) {
1298                 if (!silent)
1299                         fat_msg(sb, KERN_ERR, "bogus number of reserved sectors");
1300                 brelse(bh);
1301                 goto out_invalid;
1302         }
1303         if (!b->fats) {
1304                 if (!silent)
1305                         fat_msg(sb, KERN_ERR, "bogus number of FAT structure");
1306                 brelse(bh);
1307                 goto out_invalid;
1308         }
1309 
1310         /*
1311          * Earlier we checked here that b->secs_track and b->head are nonzero,
1312          * but it turns out valid FAT filesystems can have zero there.
1313          */
1314 
1315         media = b->media;
1316         if (!fat_valid_media(media)) {
1317                 if (!silent)
1318                         fat_msg(sb, KERN_ERR, "invalid media value (0x%02x)",
1319                                media);
1320                 brelse(bh);
1321                 goto out_invalid;
1322         }
1323         logical_sector_size = get_unaligned_le16(&b->sector_size);
1324         if (!is_power_of_2(logical_sector_size)
1325             || (logical_sector_size < 512)
1326             || (logical_sector_size > 4096)) {
1327                 if (!silent)
1328                         fat_msg(sb, KERN_ERR, "bogus logical sector size %u",
1329                                logical_sector_size);
1330                 brelse(bh);
1331                 goto out_invalid;
1332         }
1333         sbi->sec_per_clus = b->sec_per_clus;
1334         if (!is_power_of_2(sbi->sec_per_clus)) {
1335                 if (!silent)
1336                         fat_msg(sb, KERN_ERR, "bogus sectors per cluster %u",
1337                                sbi->sec_per_clus);
1338                 brelse(bh);
1339                 goto out_invalid;
1340         }
1341 
1342         if (logical_sector_size < sb->s_blocksize) {
1343                 fat_msg(sb, KERN_ERR, "logical sector size too small for device"
1344                        " (logical sector size = %u)", logical_sector_size);
1345                 brelse(bh);
1346                 goto out_fail;
1347         }
1348         if (logical_sector_size > sb->s_blocksize) {
1349                 brelse(bh);
1350 
1351                 if (!sb_set_blocksize(sb, logical_sector_size)) {
1352                         fat_msg(sb, KERN_ERR, "unable to set blocksize %u",
1353                                logical_sector_size);
1354                         goto out_fail;
1355                 }
1356                 bh = sb_bread(sb, 0);
1357                 if (bh == NULL) {
1358                         fat_msg(sb, KERN_ERR, "unable to read boot sector"
1359                                " (logical sector size = %lu)",
1360                                sb->s_blocksize);
1361                         goto out_fail;
1362                 }
1363                 b = (struct fat_boot_sector *) bh->b_data;
1364         }
1365 
1366         mutex_init(&sbi->s_lock);
1367         sbi->cluster_size = sb->s_blocksize * sbi->sec_per_clus;
1368         sbi->cluster_bits = ffs(sbi->cluster_size) - 1;
1369         sbi->fats = b->fats;
1370         sbi->fat_bits = 0;              /* Don't know yet */
1371         sbi->fat_start = le16_to_cpu(b->reserved);
1372         sbi->fat_length = le16_to_cpu(b->fat_length);
1373         sbi->root_cluster = 0;
1374         sbi->free_clusters = -1;        /* Don't know yet */
1375         sbi->free_clus_valid = 0;
1376         sbi->prev_free = FAT_START_ENT;
1377         sb->s_maxbytes = 0xffffffff;
1378 
1379         if (!sbi->fat_length && b->fat32.length) {
1380                 struct fat_boot_fsinfo *fsinfo;
1381                 struct buffer_head *fsinfo_bh;
1382 
1383                 /* Must be FAT32 */
1384                 sbi->fat_bits = 32;
1385                 sbi->fat_length = le32_to_cpu(b->fat32.length);
1386                 sbi->root_cluster = le32_to_cpu(b->fat32.root_cluster);
1387 
1388                 /* MC - if info_sector is 0, don't multiply by 0 */
1389                 sbi->fsinfo_sector = le16_to_cpu(b->fat32.info_sector);
1390                 if (sbi->fsinfo_sector == 0)
1391                         sbi->fsinfo_sector = 1;
1392 
1393                 fsinfo_bh = sb_bread(sb, sbi->fsinfo_sector);
1394                 if (fsinfo_bh == NULL) {
1395                         fat_msg(sb, KERN_ERR, "bread failed, FSINFO block"
1396                                " (sector = %lu)", sbi->fsinfo_sector);
1397                         brelse(bh);
1398                         goto out_fail;
1399                 }
1400 
1401                 fsinfo = (struct fat_boot_fsinfo *)fsinfo_bh->b_data;
1402                 if (!IS_FSINFO(fsinfo)) {
1403                         fat_msg(sb, KERN_WARNING, "Invalid FSINFO signature: "
1404                                "0x%08x, 0x%08x (sector = %lu)",
1405                                le32_to_cpu(fsinfo->signature1),
1406                                le32_to_cpu(fsinfo->signature2),
1407                                sbi->fsinfo_sector);
1408                 } else {
1409                         if (sbi->options.usefree)
1410                                 sbi->free_clus_valid = 1;
1411                         sbi->free_clusters = le32_to_cpu(fsinfo->free_clusters);
1412                         sbi->prev_free = le32_to_cpu(fsinfo->next_cluster);
1413                 }
1414 
1415                 brelse(fsinfo_bh);
1416         }
1417 
1418         /* interpret volume ID as a little endian 32 bit integer */
1419         if (sbi->fat_bits == 32)
1420                 sbi->vol_id = (((u32)b->fat32.vol_id[0]) |
1421                                         ((u32)b->fat32.vol_id[1] << 8) |
1422                                         ((u32)b->fat32.vol_id[2] << 16) |
1423                                         ((u32)b->fat32.vol_id[3] << 24));
1424         else /* fat 16 or 12 */
1425                 sbi->vol_id = (((u32)b->fat16.vol_id[0]) |
1426                                         ((u32)b->fat16.vol_id[1] << 8) |
1427                                         ((u32)b->fat16.vol_id[2] << 16) |
1428                                         ((u32)b->fat16.vol_id[3] << 24));
1429 
1430         sbi->dir_per_block = sb->s_blocksize / sizeof(struct msdos_dir_entry);
1431         sbi->dir_per_block_bits = ffs(sbi->dir_per_block) - 1;
1432 
1433         sbi->dir_start = sbi->fat_start + sbi->fats * sbi->fat_length;
1434         sbi->dir_entries = get_unaligned_le16(&b->dir_entries);
1435         if (sbi->dir_entries & (sbi->dir_per_block - 1)) {
1436                 if (!silent)
1437                         fat_msg(sb, KERN_ERR, "bogus directory-entries per block"
1438                                " (%u)", sbi->dir_entries);
1439                 brelse(bh);
1440                 goto out_invalid;
1441         }
1442 
1443         rootdir_sectors = sbi->dir_entries
1444                 * sizeof(struct msdos_dir_entry) / sb->s_blocksize;
1445         sbi->data_start = sbi->dir_start + rootdir_sectors;
1446         total_sectors = get_unaligned_le16(&b->sectors);
1447         if (total_sectors == 0)
1448                 total_sectors = le32_to_cpu(b->total_sect);
1449 
1450         total_clusters = (total_sectors - sbi->data_start) / sbi->sec_per_clus;
1451 
1452         if (sbi->fat_bits != 32)
1453                 sbi->fat_bits = (total_clusters > MAX_FAT12) ? 16 : 12;
1454 
1455         /* some OSes set FAT_STATE_DIRTY and clean it on unmount. */
1456         if (sbi->fat_bits == 32)
1457                 sbi->dirty = b->fat32.state & FAT_STATE_DIRTY;
1458         else /* fat 16 or 12 */
1459                 sbi->dirty = b->fat16.state & FAT_STATE_DIRTY;
1460 
1461         /* check that FAT table does not overflow */
1462         fat_clusters = calc_fat_clusters(sb);
1463         total_clusters = min(total_clusters, fat_clusters - FAT_START_ENT);
1464         if (total_clusters > MAX_FAT(sb)) {
1465                 if (!silent)
1466                         fat_msg(sb, KERN_ERR, "count of clusters too big (%u)",
1467                                total_clusters);
1468                 brelse(bh);
1469                 goto out_invalid;
1470         }
1471 
1472         sbi->max_cluster = total_clusters + FAT_START_ENT;
1473         /* check the free_clusters, it's not necessarily correct */
1474         if (sbi->free_clusters != -1 && sbi->free_clusters > total_clusters)
1475                 sbi->free_clusters = -1;
1476         /* check the prev_free, it's not necessarily correct */
1477         sbi->prev_free %= sbi->max_cluster;
1478         if (sbi->prev_free < FAT_START_ENT)
1479                 sbi->prev_free = FAT_START_ENT;
1480 
1481         brelse(bh);
1482 
1483         /* set up enough so that it can read an inode */
1484         fat_hash_init(sb);
1485         dir_hash_init(sb);
1486         fat_ent_access_init(sb);
1487 
1488         /*
1489          * The low byte of FAT's first entry must have same value with
1490          * media-field.  But in real world, too many devices is
1491          * writing wrong value.  So, removed that validity check.
1492          *
1493          * if (FAT_FIRST_ENT(sb, media) != first)
1494          */
1495 
1496         error = -EINVAL;
1497         sprintf(buf, "cp%d", sbi->options.codepage);
1498         sbi->nls_disk = load_nls(buf);
1499         if (!sbi->nls_disk) {
1500                 fat_msg(sb, KERN_ERR, "codepage %s not found", buf);
1501                 goto out_fail;
1502         }
1503 
1504         /* FIXME: utf8 is using iocharset for upper/lower conversion */
1505         if (sbi->options.isvfat) {
1506                 sbi->nls_io = load_nls(sbi->options.iocharset);
1507                 if (!sbi->nls_io) {
1508                         fat_msg(sb, KERN_ERR, "IO charset %s not found",
1509                                sbi->options.iocharset);
1510                         goto out_fail;
1511                 }
1512         }
1513 
1514         error = -ENOMEM;
1515         fat_inode = new_inode(sb);
1516         if (!fat_inode)
1517                 goto out_fail;
1518         MSDOS_I(fat_inode)->i_pos = 0;
1519         sbi->fat_inode = fat_inode;
1520 
1521         fsinfo_inode = new_inode(sb);
1522         if (!fsinfo_inode)
1523                 goto out_fail;
1524         fsinfo_inode->i_ino = MSDOS_FSINFO_INO;
1525         sbi->fsinfo_inode = fsinfo_inode;
1526         insert_inode_hash(fsinfo_inode);
1527 
1528         root_inode = new_inode(sb);
1529         if (!root_inode)
1530                 goto out_fail;
1531         root_inode->i_ino = MSDOS_ROOT_INO;
1532         root_inode->i_version = 1;
1533         error = fat_read_root(root_inode);
1534         if (error < 0) {
1535                 iput(root_inode);
1536                 goto out_fail;
1537         }
1538         error = -ENOMEM;
1539         insert_inode_hash(root_inode);
1540         fat_attach(root_inode, 0);
1541         sb->s_root = d_make_root(root_inode);
1542         if (!sb->s_root) {
1543                 fat_msg(sb, KERN_ERR, "get root inode failed");
1544                 goto out_fail;
1545         }
1546 
1547         if (sbi->options.discard) {
1548                 struct request_queue *q = bdev_get_queue(sb->s_bdev);
1549                 if (!blk_queue_discard(q))
1550                         fat_msg(sb, KERN_WARNING,
1551                                         "mounting with \"discard\" option, but "
1552                                         "the device does not support discard");
1553         }
1554 
1555         fat_set_state(sb, 1, 0);
1556         return 0;
1557 
1558 out_invalid:
1559         error = -EINVAL;
1560         if (!silent)
1561                 fat_msg(sb, KERN_INFO, "Can't find a valid FAT filesystem");
1562 
1563 out_fail:
1564         if (fsinfo_inode)
1565                 iput(fsinfo_inode);
1566         if (fat_inode)
1567                 iput(fat_inode);
1568         unload_nls(sbi->nls_io);
1569         unload_nls(sbi->nls_disk);
1570         if (sbi->options.iocharset != fat_default_iocharset)
1571                 kfree(sbi->options.iocharset);
1572         sb->s_fs_info = NULL;
1573         kfree(sbi);
1574         return error;
1575 }
1576 
1577 EXPORT_SYMBOL_GPL(fat_fill_super);
1578 
1579 /*
1580  * helper function for fat_flush_inodes.  This writes both the inode
1581  * and the file data blocks, waiting for in flight data blocks before
1582  * the start of the call.  It does not wait for any io started
1583  * during the call
1584  */
1585 static int writeback_inode(struct inode *inode)
1586 {
1587 
1588         int ret;
1589 
1590         /* if we used wait=1, sync_inode_metadata waits for the io for the
1591         * inode to finish.  So wait=0 is sent down to sync_inode_metadata
1592         * and filemap_fdatawrite is used for the data blocks
1593         */
1594         ret = sync_inode_metadata(inode, 0);
1595         if (!ret)
1596                 ret = filemap_fdatawrite(inode->i_mapping);
1597         return ret;
1598 }
1599 
1600 /*
1601  * write data and metadata corresponding to i1 and i2.  The io is
1602  * started but we do not wait for any of it to finish.
1603  *
1604  * filemap_flush is used for the block device, so if there is a dirty
1605  * page for a block already in flight, we will not wait and start the
1606  * io over again
1607  */
1608 int fat_flush_inodes(struct super_block *sb, struct inode *i1, struct inode *i2)
1609 {
1610         int ret = 0;
1611         if (!MSDOS_SB(sb)->options.flush)
1612                 return 0;
1613         if (i1)
1614                 ret = writeback_inode(i1);
1615         if (!ret && i2)
1616                 ret = writeback_inode(i2);
1617         if (!ret) {
1618                 struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping;
1619                 ret = filemap_flush(mapping);
1620         }
1621         return ret;
1622 }
1623 EXPORT_SYMBOL_GPL(fat_flush_inodes);
1624 
1625 static int __init init_fat_fs(void)
1626 {
1627         int err;
1628 
1629         err = fat_cache_init();
1630         if (err)
1631                 return err;
1632 
1633         err = fat_init_inodecache();
1634         if (err)
1635                 goto failed;
1636 
1637         return 0;
1638 
1639 failed:
1640         fat_cache_destroy();
1641         return err;
1642 }
1643 
1644 static void __exit exit_fat_fs(void)
1645 {
1646         fat_cache_destroy();
1647         fat_destroy_inodecache();
1648 }
1649 
1650 module_init(init_fat_fs)
1651 module_exit(exit_fat_fs)
1652 
1653 MODULE_LICENSE("GPL");
1654 

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