fs/fat/inode.c

   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 <linux/iversion.h>
  24 #include "fat.h"
  25
  26 #ifndef CONFIG_FAT_DEFAULT_IOCHARSET
  27 /* if user don't select VFAT, this is undefined. */
  28 #define CONFIG_FAT_DEFAULT_IOCHARSET    ""
  29 #endif
  30
  31 #define KB_IN_SECTORS 2
  32
  33 /*
  34  * A deserialized copy of the on-disk structure laid out in struct
  35  * fat_boot_sector.
  36  */
  37 struct fat_bios_param_block {
  38         u16     fat_sector_size;
  39         u8      fat_sec_per_clus;
  40         u16     fat_reserved;
  41         u8      fat_fats;
  42         u16     fat_dir_entries;
  43         u16     fat_sectors;
  44         u16     fat_fat_length;
  45         u32     fat_total_sect;
  46
  47         u8      fat16_state;
  48         u32     fat16_vol_id;
  49
  50         u32     fat32_length;
  51         u32     fat32_root_cluster;
  52         u16     fat32_info_sector;
  53         u8      fat32_state;
  54         u32     fat32_vol_id;
  55 };
  56
  57 static int fat_default_codepage = CONFIG_FAT_DEFAULT_CODEPAGE;
  58 static char fat_default_iocharset[] = CONFIG_FAT_DEFAULT_IOCHARSET;
  59
  60 static struct fat_floppy_defaults {
  61         unsigned nr_sectors;
  62         unsigned sec_per_clus;
  63         unsigned dir_entries;
  64         unsigned media;
  65         unsigned fat_length;
  66 } floppy_defaults[] = {
  67 {
  68         .nr_sectors = 160 * KB_IN_SECTORS,
  69         .sec_per_clus = 1,
  70         .dir_entries = 64,
  71         .media = 0xFE,
  72         .fat_length = 1,
  73 },
  74 {
  75         .nr_sectors = 180 * KB_IN_SECTORS,
  76         .sec_per_clus = 1,
  77         .dir_entries = 64,
  78         .media = 0xFC,
  79         .fat_length = 2,
  80 },
  81 {
  82         .nr_sectors = 320 * KB_IN_SECTORS,
  83         .sec_per_clus = 2,
  84         .dir_entries = 112,
  85         .media = 0xFF,
  86         .fat_length = 1,
  87 },
  88 {
  89         .nr_sectors = 360 * KB_IN_SECTORS,
  90         .sec_per_clus = 2,
  91         .dir_entries = 112,
  92         .media = 0xFD,
  93         .fat_length = 2,
  94 },
  95 };
  96
  97 int fat_add_cluster(struct inode *inode)
  98 {
  99         int err, cluster;
 100
 101         err = fat_alloc_clusters(inode, &cluster, 1);
 102         if (err)
 103                 return err;
 104         /* FIXME: this cluster should be added after data of this
 105          * cluster is writed */
 106         err = fat_chain_add(inode, cluster, 1);
 107         if (err)
 108                 fat_free_clusters(inode, cluster);
 109         return err;
 110 }
 111
 112 static inline int __fat_get_block(struct inode *inode, sector_t iblock,
 113                                   unsigned long *max_blocks,
 114                                   struct buffer_head *bh_result, int create)
 115 {
 116         struct super_block *sb = inode->i_sb;
 117         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 118         unsigned long mapped_blocks;
 119         sector_t phys, last_block;
 120         int err, offset;
 121
 122         err = fat_bmap(inode, iblock, &phys, &mapped_blocks, create, false);
 123         if (err)
 124                 return err;
 125         if (phys) {
 126                 map_bh(bh_result, sb, phys);
 127                 *max_blocks = min(mapped_blocks, *max_blocks);
 128                 return 0;
 129         }
 130         if (!create)
 131                 return 0;
 132
 133         if (iblock != MSDOS_I(inode)->mmu_private >> sb->s_blocksize_bits) {
 134                 fat_fs_error(sb, "corrupted file size (i_pos %lld, %lld)",
 135                         MSDOS_I(inode)->i_pos, MSDOS_I(inode)->mmu_private);
 136                 return -EIO;
 137         }
 138
 139         last_block = inode->i_blocks >> (sb->s_blocksize_bits - 9);
 140         offset = (unsigned long)iblock & (sbi->sec_per_clus - 1);
 141         /*
 142          * allocate a cluster according to the following.
 143          * 1) no more available blocks
 144          * 2) not part of fallocate region
 145          */
 146         if (!offset && !(iblock < last_block)) {
 147                 /* TODO: multiple cluster allocation would be desirable. */
 148                 err = fat_add_cluster(inode);
 149                 if (err)
 150                         return err;
 151         }
 152         /* available blocks on this cluster */
 153         mapped_blocks = sbi->sec_per_clus - offset;
 154
 155         *max_blocks = min(mapped_blocks, *max_blocks);
 156         MSDOS_I(inode)->mmu_private += *max_blocks << sb->s_blocksize_bits;
 157
 158         err = fat_bmap(inode, iblock, &phys, &mapped_blocks, create, false);
 159         if (err)
 160                 return err;
 161         if (!phys) {
 162                 fat_fs_error(sb,
 163                              "invalid FAT chain (i_pos %lld, last_block %llu)",
 164                              MSDOS_I(inode)->i_pos,
 165                              (unsigned long long)last_block);
 166                 return -EIO;
 167         }
 168
 169         BUG_ON(*max_blocks != mapped_blocks);
 170         set_buffer_new(bh_result);
 171         map_bh(bh_result, sb, phys);
 172
 173         return 0;
 174 }
 175
 176 static int fat_get_block(struct inode *inode, sector_t iblock,
 177                          struct buffer_head *bh_result, int create)
 178 {
 179         struct super_block *sb = inode->i_sb;
 180         unsigned long max_blocks = bh_result->b_size >> inode->i_blkbits;
 181         int err;
 182
 183         err = __fat_get_block(inode, iblock, &max_blocks, bh_result, create);
 184         if (err)
 185                 return err;
 186         bh_result->b_size = max_blocks << sb->s_blocksize_bits;
 187         return 0;
 188 }
 189
 190 static int fat_writepage(struct page *page, struct writeback_control *wbc)
 191 {
 192         return block_write_full_page(page, fat_get_block, wbc);
 193 }
 194
 195 static int fat_writepages(struct address_space *mapping,
 196                           struct writeback_control *wbc)
 197 {
 198         return mpage_writepages(mapping, wbc, fat_get_block);
 199 }
 200
 201 static int fat_readpage(struct file *file, struct page *page)
 202 {
 203         return mpage_readpage(page, fat_get_block);
 204 }
 205
 206 static int fat_readpages(struct file *file, struct address_space *mapping,
 207                          struct list_head *pages, unsigned nr_pages)
 208 {
 209         return mpage_readpages(mapping, pages, nr_pages, fat_get_block);
 210 }
 211
 212 static void fat_write_failed(struct address_space *mapping, loff_t to)
 213 {
 214         struct inode *inode = mapping->host;
 215
 216         if (to > inode->i_size) {
 217                 truncate_pagecache(inode, inode->i_size);
 218                 fat_truncate_blocks(inode, inode->i_size);
 219         }
 220 }
 221
 222 static int fat_write_begin(struct file *file, struct address_space *mapping,
 223                         loff_t pos, unsigned len, unsigned flags,
 224                         struct page **pagep, void **fsdata)
 225 {
 226         int err;
 227
 228         *pagep = NULL;
 229         err = cont_write_begin(file, mapping, pos, len, flags,
 230                                 pagep, fsdata, fat_get_block,
 231                                 &MSDOS_I(mapping->host)->mmu_private);
 232         if (err < 0)
 233                 fat_write_failed(mapping, pos + len);
 234         return err;
 235 }
 236
 237 static int fat_write_end(struct file *file, struct address_space *mapping,
 238                         loff_t pos, unsigned len, unsigned copied,
 239                         struct page *pagep, void *fsdata)
 240 {
 241         struct inode *inode = mapping->host;
 242         int err;
 243         err = generic_write_end(file, mapping, pos, len, copied, pagep, fsdata);
 244         if (err < len)
 245                 fat_write_failed(mapping, pos + len);
 246         if (!(err < 0) && !(MSDOS_I(inode)->i_attrs & ATTR_ARCH)) {
 247                 inode->i_mtime = inode->i_ctime = current_time(inode);
 248                 MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
 249                 mark_inode_dirty(inode);
 250         }
 251         return err;
 252 }
 253
 254 static ssize_t fat_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
 255 {
 256         struct file *file = iocb->ki_filp;
 257         struct address_space *mapping = file->f_mapping;
 258         struct inode *inode = mapping->host;
 259         size_t count = iov_iter_count(iter);
 260         loff_t offset = iocb->ki_pos;
 261         ssize_t ret;
 262
 263         if (iov_iter_rw(iter) == WRITE) {
 264                 /*
 265                  * FIXME: blockdev_direct_IO() doesn't use ->write_begin(),
 266                  * so we need to update the ->mmu_private to block boundary.
 267                  *
 268                  * But we must fill the remaining area or hole by nul for
 269                  * updating ->mmu_private.
 270                  *
 271                  * Return 0, and fallback to normal buffered write.
 272                  */
 273                 loff_t size = offset + count;
 274                 if (MSDOS_I(inode)->mmu_private < size)
 275                         return 0;
 276         }
 277
 278         /*
 279          * FAT need to use the DIO_LOCKING for avoiding the race
 280          * condition of fat_get_block() and ->truncate().
 281          */
 282         ret = blockdev_direct_IO(iocb, inode, iter, fat_get_block);
 283         if (ret < 0 && iov_iter_rw(iter) == WRITE)
 284                 fat_write_failed(mapping, offset + count);
 285
 286         return ret;
 287 }
 288
 289 static int fat_get_block_bmap(struct inode *inode, sector_t iblock,
 290                 struct buffer_head *bh_result, int create)
 291 {
 292         struct super_block *sb = inode->i_sb;
 293         unsigned long max_blocks = bh_result->b_size >> inode->i_blkbits;
 294         int err;
 295         sector_t bmap;
 296         unsigned long mapped_blocks;
 297
 298         BUG_ON(create != 0);
 299
 300         err = fat_bmap(inode, iblock, &bmap, &mapped_blocks, create, true);
 301         if (err)
 302                 return err;
 303
 304         if (bmap) {
 305                 map_bh(bh_result, sb, bmap);
 306                 max_blocks = min(mapped_blocks, max_blocks);
 307         }
 308
 309         bh_result->b_size = max_blocks << sb->s_blocksize_bits;
 310
 311         return 0;
 312 }
 313
 314 static sector_t _fat_bmap(struct address_space *mapping, sector_t block)
 315 {
 316         sector_t blocknr;
 317
 318         /* fat_get_cluster() assumes the requested blocknr isn't truncated. */
 319         down_read(&MSDOS_I(mapping->host)->truncate_lock);
 320         blocknr = generic_block_bmap(mapping, block, fat_get_block_bmap);
 321         up_read(&MSDOS_I(mapping->host)->truncate_lock);
 322
 323         return blocknr;
 324 }
 325
 326 /*
 327  * fat_block_truncate_page() zeroes out a mapping from file offset `from'
 328  * up to the end of the block which corresponds to `from'.
 329  * This is required during truncate to physically zeroout the tail end
 330  * of that block so it doesn't yield old data if the file is later grown.
 331  * Also, avoid causing failure from fsx for cases of "data past EOF"
 332  */
 333 int fat_block_truncate_page(struct inode *inode, loff_t from)
 334 {
 335         return block_truncate_page(inode->i_mapping, from, fat_get_block);
 336 }
 337
 338 static const struct address_space_operations fat_aops = {
 339         .readpage       = fat_readpage,
 340         .readpages      = fat_readpages,
 341         .writepage      = fat_writepage,
 342         .writepages     = fat_writepages,
 343         .write_begin    = fat_write_begin,
 344         .write_end      = fat_write_end,
 345         .direct_IO      = fat_direct_IO,
 346         .bmap           = _fat_bmap
 347 };
 348
 349 /*
 350  * New FAT inode stuff. We do the following:
 351  *      a) i_ino is constant and has nothing with on-disk location.
 352  *      b) FAT manages its own cache of directory entries.
 353  *      c) *This* cache is indexed by on-disk location.
 354  *      d) inode has an associated directory entry, all right, but
 355  *              it may be unhashed.
 356  *      e) currently entries are stored within struct inode. That should
 357  *              change.
 358  *      f) we deal with races in the following way:
 359  *              1. readdir() and lookup() do FAT-dir-cache lookup.
 360  *              2. rename() unhashes the F-d-c entry and rehashes it in
 361  *                      a new place.
 362  *              3. unlink() and rmdir() unhash F-d-c entry.
 363  *              4. fat_write_inode() checks whether the thing is unhashed.
 364  *                      If it is we silently return. If it isn't we do bread(),
 365  *                      check if the location is still valid and retry if it
 366  *                      isn't. Otherwise we do changes.
 367  *              5. Spinlock is used to protect hash/unhash/location check/lookup
 368  *              6. fat_evict_inode() unhashes the F-d-c entry.
 369  *              7. lookup() and readdir() do igrab() if they find a F-d-c entry
 370  *                      and consider negative result as cache miss.
 371  */
 372
 373 static void fat_hash_init(struct super_block *sb)
 374 {
 375         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 376         int i;
 377
 378         spin_lock_init(&sbi->inode_hash_lock);
 379         for (i = 0; i < FAT_HASH_SIZE; i++)
 380                 INIT_HLIST_HEAD(&sbi->inode_hashtable[i]);
 381 }
 382
 383 static inline unsigned long fat_hash(loff_t i_pos)
 384 {
 385         return hash_32(i_pos, FAT_HASH_BITS);
 386 }
 387
 388 static void dir_hash_init(struct super_block *sb)
 389 {
 390         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 391         int i;
 392
 393         spin_lock_init(&sbi->dir_hash_lock);
 394         for (i = 0; i < FAT_HASH_SIZE; i++)
 395                 INIT_HLIST_HEAD(&sbi->dir_hashtable[i]);
 396 }
 397
 398 void fat_attach(struct inode *inode, loff_t i_pos)
 399 {
 400         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 401
 402         if (inode->i_ino != MSDOS_ROOT_INO) {
 403                 struct hlist_head *head =   sbi->inode_hashtable
 404                                           + fat_hash(i_pos);
 405
 406                 spin_lock(&sbi->inode_hash_lock);
 407                 MSDOS_I(inode)->i_pos = i_pos;
 408                 hlist_add_head(&MSDOS_I(inode)->i_fat_hash, head);
 409                 spin_unlock(&sbi->inode_hash_lock);
 410         }
 411
 412         /* If NFS support is enabled, cache the mapping of start cluster
 413          * to directory inode. This is used during reconnection of
 414          * dentries to the filesystem root.
 415          */
 416         if (S_ISDIR(inode->i_mode) && sbi->options.nfs) {
 417                 struct hlist_head *d_head = sbi->dir_hashtable;
 418                 d_head += fat_dir_hash(MSDOS_I(inode)->i_logstart);
 419
 420                 spin_lock(&sbi->dir_hash_lock);
 421                 hlist_add_head(&MSDOS_I(inode)->i_dir_hash, d_head);
 422                 spin_unlock(&sbi->dir_hash_lock);
 423         }
 424 }
 425 EXPORT_SYMBOL_GPL(fat_attach);
 426
 427 void fat_detach(struct inode *inode)
 428 {
 429         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 430         spin_lock(&sbi->inode_hash_lock);
 431         MSDOS_I(inode)->i_pos = 0;
 432         hlist_del_init(&MSDOS_I(inode)->i_fat_hash);
 433         spin_unlock(&sbi->inode_hash_lock);
 434
 435         if (S_ISDIR(inode->i_mode) && sbi->options.nfs) {
 436                 spin_lock(&sbi->dir_hash_lock);
 437                 hlist_del_init(&MSDOS_I(inode)->i_dir_hash);
 438                 spin_unlock(&sbi->dir_hash_lock);
 439         }
 440 }
 441 EXPORT_SYMBOL_GPL(fat_detach);
 442
 443 struct inode *fat_iget(struct super_block *sb, loff_t i_pos)
 444 {
 445         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 446         struct hlist_head *head = sbi->inode_hashtable + fat_hash(i_pos);
 447         struct msdos_inode_info *i;
 448         struct inode *inode = NULL;
 449
 450         spin_lock(&sbi->inode_hash_lock);
 451         hlist_for_each_entry(i, head, i_fat_hash) {
 452                 BUG_ON(i->vfs_inode.i_sb != sb);
 453                 if (i->i_pos != i_pos)
 454                         continue;
 455                 inode = igrab(&i->vfs_inode);
 456                 if (inode)
 457                         break;
 458         }
 459         spin_unlock(&sbi->inode_hash_lock);
 460         return inode;
 461 }
 462
 463 static int is_exec(unsigned char *extension)
 464 {
 465         unsigned char exe_extensions[] = "EXECOMBAT", *walk;
 466
 467         for (walk = exe_extensions; *walk; walk += 3)
 468                 if (!strncmp(extension, walk, 3))
 469                         return 1;
 470         return 0;
 471 }
 472
 473 static int fat_calc_dir_size(struct inode *inode)
 474 {
 475         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 476         int ret, fclus, dclus;
 477
 478         inode->i_size = 0;
 479         if (MSDOS_I(inode)->i_start == 0)
 480                 return 0;
 481
 482         ret = fat_get_cluster(inode, FAT_ENT_EOF, &fclus, &dclus);
 483         if (ret < 0)
 484                 return ret;
 485         inode->i_size = (fclus + 1) << sbi->cluster_bits;
 486
 487         return 0;
 488 }
 489
 490 static int fat_validate_dir(struct inode *dir)
 491 {
 492         struct super_block *sb = dir->i_sb;
 493
 494         if (dir->i_nlink < 2) {
 495                 /* Directory should have "."/".." entries at least. */
 496                 fat_fs_error(sb, "corrupted directory (invalid entries)");
 497                 return -EIO;
 498         }
 499         if (MSDOS_I(dir)->i_start == 0 ||
 500             MSDOS_I(dir)->i_start == MSDOS_SB(sb)->root_cluster) {
 501                 /* Directory should point valid cluster. */
 502                 fat_fs_error(sb, "corrupted directory (invalid i_start)");
 503                 return -EIO;
 504         }
 505         return 0;
 506 }
 507
 508 /* doesn't deal with root inode */
 509 int fat_fill_inode(struct inode *inode, struct msdos_dir_entry *de)
 510 {
 511         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 512         int error;
 513
 514         MSDOS_I(inode)->i_pos = 0;
 515         inode->i_uid = sbi->options.fs_uid;
 516         inode->i_gid = sbi->options.fs_gid;
 517         inode_inc_iversion(inode);
 518         inode->i_generation = get_seconds();
 519
 520         if ((de->attr & ATTR_DIR) && !IS_FREE(de->name)) {
 521                 inode->i_generation &= ~1;
 522                 inode->i_mode = fat_make_mode(sbi, de->attr, S_IRWXUGO);
 523                 inode->i_op = sbi->dir_ops;
 524                 inode->i_fop = &fat_dir_operations;
 525
 526                 MSDOS_I(inode)->i_start = fat_get_start(sbi, de);
 527                 MSDOS_I(inode)->i_logstart = MSDOS_I(inode)->i_start;
 528                 error = fat_calc_dir_size(inode);
 529                 if (error < 0)
 530                         return error;
 531                 MSDOS_I(inode)->mmu_private = inode->i_size;
 532
 533                 set_nlink(inode, fat_subdirs(inode));
 534
 535                 error = fat_validate_dir(inode);
 536                 if (error < 0)
 537                         return error;
 538         } else { /* not a directory */
 539                 inode->i_generation |= 1;
 540                 inode->i_mode = fat_make_mode(sbi, de->attr,
 541                         ((sbi->options.showexec && !is_exec(de->name + 8))
 542                          ? S_IRUGO|S_IWUGO : S_IRWXUGO));
 543                 MSDOS_I(inode)->i_start = fat_get_start(sbi, de);
 544
 545                 MSDOS_I(inode)->i_logstart = MSDOS_I(inode)->i_start;
 546                 inode->i_size = le32_to_cpu(de->size);
 547                 inode->i_op = &fat_file_inode_operations;
 548                 inode->i_fop = &fat_file_operations;
 549                 inode->i_mapping->a_ops = &fat_aops;
 550                 MSDOS_I(inode)->mmu_private = inode->i_size;
 551         }
 552         if (de->attr & ATTR_SYS) {
 553                 if (sbi->options.sys_immutable)
 554                         inode->i_flags |= S_IMMUTABLE;
 555         }
 556         fat_save_attrs(inode, de->attr);
 557
 558         inode->i_blocks = ((inode->i_size + (sbi->cluster_size - 1))
 559                            & ~((loff_t)sbi->cluster_size - 1)) >> 9;
 560
 561         fat_time_fat2unix(sbi, &inode->i_mtime, de->time, de->date, 0);
 562         if (sbi->options.isvfat) {
 563                 fat_time_fat2unix(sbi, &inode->i_ctime, de->ctime,
 564                                   de->cdate, de->ctime_cs);
 565                 fat_time_fat2unix(sbi, &inode->i_atime, 0, de->adate, 0);
 566         } else
 567                 inode->i_ctime = inode->i_atime = inode->i_mtime;
 568
 569         return 0;
 570 }
 571
 572 static inline void fat_lock_build_inode(struct msdos_sb_info *sbi)
 573 {
 574         if (sbi->options.nfs == FAT_NFS_NOSTALE_RO)
 575                 mutex_lock(&sbi->nfs_build_inode_lock);
 576 }
 577
 578 static inline void fat_unlock_build_inode(struct msdos_sb_info *sbi)
 579 {
 580         if (sbi->options.nfs == FAT_NFS_NOSTALE_RO)
 581                 mutex_unlock(&sbi->nfs_build_inode_lock);
 582 }
 583
 584 struct inode *fat_build_inode(struct super_block *sb,
 585                         struct msdos_dir_entry *de, loff_t i_pos)
 586 {
 587         struct inode *inode;
 588         int err;
 589
 590         fat_lock_build_inode(MSDOS_SB(sb));
 591         inode = fat_iget(sb, i_pos);
 592         if (inode)
 593                 goto out;
 594         inode = new_inode(sb);
 595         if (!inode) {
 596                 inode = ERR_PTR(-ENOMEM);
 597                 goto out;
 598         }
 599         inode->i_ino = iunique(sb, MSDOS_ROOT_INO);
 600         inode_set_iversion(inode, 1);
 601         err = fat_fill_inode(inode, de);
 602         if (err) {
 603                 iput(inode);
 604                 inode = ERR_PTR(err);
 605                 goto out;
 606         }
 607         fat_attach(inode, i_pos);
 608         insert_inode_hash(inode);
 609 out:
 610         fat_unlock_build_inode(MSDOS_SB(sb));
 611         return inode;
 612 }
 613
 614 EXPORT_SYMBOL_GPL(fat_build_inode);
 615
 616 static int __fat_write_inode(struct inode *inode, int wait);
 617
 618 static void fat_free_eofblocks(struct inode *inode)
 619 {
 620         /* Release unwritten fallocated blocks on inode eviction. */
 621         if ((inode->i_blocks << 9) >
 622                         round_up(MSDOS_I(inode)->mmu_private,
 623                                 MSDOS_SB(inode->i_sb)->cluster_size)) {
 624                 int err;
 625
 626                 fat_truncate_blocks(inode, MSDOS_I(inode)->mmu_private);
 627                 /* Fallocate results in updating the i_start/iogstart
 628                  * for the zero byte file. So, make it return to
 629                  * original state during evict and commit it to avoid
 630                  * any corruption on the next access to the cluster
 631                  * chain for the file.
 632                  */
 633                 err = __fat_write_inode(inode, inode_needs_sync(inode));
 634                 if (err) {
 635                         fat_msg(inode->i_sb, KERN_WARNING, "Failed to "
 636                                         "update on disk inode for unused "
 637                                         "fallocated blocks, inode could be "
 638                                         "corrupted. Please run fsck");
 639                 }
 640
 641         }
 642 }
 643
 644 static void fat_evict_inode(struct inode *inode)
 645 {
 646         truncate_inode_pages_final(&inode->i_data);
 647         if (!inode->i_nlink) {
 648                 inode->i_size = 0;
 649                 fat_truncate_blocks(inode, 0);
 650         } else
 651                 fat_free_eofblocks(inode);
 652
 653         invalidate_inode_buffers(inode);
 654         clear_inode(inode);
 655         fat_cache_inval_inode(inode);
 656         fat_detach(inode);
 657 }
 658
 659 static void fat_set_state(struct super_block *sb,
 660                         unsigned int set, unsigned int force)
 661 {
 662         struct buffer_head *bh;
 663         struct fat_boot_sector *b;
 664         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 665
 666         /* do not change any thing if mounted read only */
 667         if (sb_rdonly(sb) && !force)
 668                 return;
 669
 670         /* do not change state if fs was dirty */
 671         if (sbi->dirty) {
 672                 /* warn only on set (mount). */
 673                 if (set)
 674                         fat_msg(sb, KERN_WARNING, "Volume was not properly "
 675                                 "unmounted. Some data may be corrupt. "
 676                                 "Please run fsck.");
 677                 return;
 678         }
 679
 680         bh = sb_bread(sb, 0);
 681         if (bh == NULL) {
 682                 fat_msg(sb, KERN_ERR, "unable to read boot sector "
 683                         "to mark fs as dirty");
 684                 return;
 685         }
 686
 687         b = (struct fat_boot_sector *) bh->b_data;
 688
 689         if (sbi->fat_bits == 32) {
 690                 if (set)
 691                         b->fat32.state |= FAT_STATE_DIRTY;
 692                 else
 693                         b->fat32.state &= ~FAT_STATE_DIRTY;
 694         } else /* fat 16 and 12 */ {
 695                 if (set)
 696                         b->fat16.state |= FAT_STATE_DIRTY;
 697                 else
 698                         b->fat16.state &= ~FAT_STATE_DIRTY;
 699         }
 700
 701         mark_buffer_dirty(bh);
 702         sync_dirty_buffer(bh);
 703         brelse(bh);
 704 }
 705
 706 static void fat_reset_iocharset(struct fat_mount_options *opts)
 707 {
 708         if (opts->iocharset != fat_default_iocharset) {
 709                 /* Note: opts->iocharset can be NULL here */
 710                 kfree(opts->iocharset);
 711                 opts->iocharset = fat_default_iocharset;
 712         }
 713 }
 714
 715 static void delayed_free(struct rcu_head *p)
 716 {
 717         struct msdos_sb_info *sbi = container_of(p, struct msdos_sb_info, rcu);
 718         unload_nls(sbi->nls_disk);
 719         unload_nls(sbi->nls_io);
 720         fat_reset_iocharset(&sbi->options);
 721         kfree(sbi);
 722 }
 723
 724 static void fat_put_super(struct super_block *sb)
 725 {
 726         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 727
 728         fat_set_state(sb, 0, 0);
 729
 730         iput(sbi->fsinfo_inode);
 731         iput(sbi->fat_inode);
 732
 733         call_rcu(&sbi->rcu, delayed_free);
 734 }
 735
 736 static struct kmem_cache *fat_inode_cachep;
 737
 738 static struct inode *fat_alloc_inode(struct super_block *sb)
 739 {
 740         struct msdos_inode_info *ei;
 741         ei = kmem_cache_alloc(fat_inode_cachep, GFP_NOFS);
 742         if (!ei)
 743                 return NULL;
 744
 745         init_rwsem(&ei->truncate_lock);
 746         /* Zeroing to allow iput() even if partial initialized inode. */
 747         ei->mmu_private = 0;
 748         ei->i_start = 0;
 749         ei->i_logstart = 0;
 750         ei->i_attrs = 0;
 751         ei->i_pos = 0;
 752
 753         return &ei->vfs_inode;
 754 }
 755
 756 static void fat_i_callback(struct rcu_head *head)
 757 {
 758         struct inode *inode = container_of(head, struct inode, i_rcu);
 759         kmem_cache_free(fat_inode_cachep, MSDOS_I(inode));
 760 }
 761
 762 static void fat_destroy_inode(struct inode *inode)
 763 {
 764         call_rcu(&inode->i_rcu, fat_i_callback);
 765 }
 766
 767 static void init_once(void *foo)
 768 {
 769         struct msdos_inode_info *ei = (struct msdos_inode_info *)foo;
 770
 771         spin_lock_init(&ei->cache_lru_lock);
 772         ei->nr_caches = 0;
 773         ei->cache_valid_id = FAT_CACHE_VALID + 1;
 774         INIT_LIST_HEAD(&ei->cache_lru);
 775         INIT_HLIST_NODE(&ei->i_fat_hash);
 776         INIT_HLIST_NODE(&ei->i_dir_hash);
 777         inode_init_once(&ei->vfs_inode);
 778 }
 779
 780 static int __init fat_init_inodecache(void)
 781 {
 782         fat_inode_cachep = kmem_cache_create("fat_inode_cache",
 783                                              sizeof(struct msdos_inode_info),
 784                                              0, (SLAB_RECLAIM_ACCOUNT|
 785                                                 SLAB_MEM_SPREAD|SLAB_ACCOUNT),
 786                                              init_once);
 787         if (fat_inode_cachep == NULL)
 788                 return -ENOMEM;
 789         return 0;
 790 }
 791
 792 static void __exit fat_destroy_inodecache(void)
 793 {
 794         /*
 795          * Make sure all delayed rcu free inodes are flushed before we
 796          * destroy cache.
 797          */
 798         rcu_barrier();
 799         kmem_cache_destroy(fat_inode_cachep);
 800 }
 801
 802 static int fat_remount(struct super_block *sb, int *flags, char *data)
 803 {
 804         bool new_rdonly;
 805         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 806         *flags |= SB_NODIRATIME | (sbi->options.isvfat ? 0 : SB_NOATIME);
 807
 808         sync_filesystem(sb);
 809
 810         /* make sure we update state on remount. */
 811         new_rdonly = *flags & SB_RDONLY;
 812         if (new_rdonly != sb_rdonly(sb)) {
 813                 if (new_rdonly)
 814                         fat_set_state(sb, 0, 0);
 815                 else
 816                         fat_set_state(sb, 1, 1);
 817         }
 818         return 0;
 819 }
 820
 821 static int fat_statfs(struct dentry *dentry, struct kstatfs *buf)
 822 {
 823         struct super_block *sb = dentry->d_sb;
 824         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 825         u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
 826
 827         /* If the count of free cluster is still unknown, counts it here. */
 828         if (sbi->free_clusters == -1 || !sbi->free_clus_valid) {
 829                 int err = fat_count_free_clusters(dentry->d_sb);
 830                 if (err)
 831                         return err;
 832         }
 833
 834         buf->f_type = dentry->d_sb->s_magic;
 835         buf->f_bsize = sbi->cluster_size;
 836         buf->f_blocks = sbi->max_cluster - FAT_START_ENT;
 837         buf->f_bfree = sbi->free_clusters;
 838         buf->f_bavail = sbi->free_clusters;
 839         buf->f_fsid.val[0] = (u32)id;
 840         buf->f_fsid.val[1] = (u32)(id >> 32);
 841         buf->f_namelen =
 842                 (sbi->options.isvfat ? FAT_LFN_LEN : 12) * NLS_MAX_CHARSET_SIZE;
 843
 844         return 0;
 845 }
 846
 847 static int __fat_write_inode(struct inode *inode, int wait)
 848 {
 849         struct super_block *sb = inode->i_sb;
 850         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 851         struct buffer_head *bh;
 852         struct msdos_dir_entry *raw_entry;
 853         loff_t i_pos;
 854         sector_t blocknr;
 855         int err, offset;
 856
 857         if (inode->i_ino == MSDOS_ROOT_INO)
 858                 return 0;
 859
 860 retry:
 861         i_pos = fat_i_pos_read(sbi, inode);
 862         if (!i_pos)
 863                 return 0;
 864
 865         fat_get_blknr_offset(sbi, i_pos, &blocknr, &offset);
 866         bh = sb_bread(sb, blocknr);
 867         if (!bh) {
 868                 fat_msg(sb, KERN_ERR, "unable to read inode block "
 869                        "for updating (i_pos %lld)", i_pos);
 870                 return -EIO;
 871         }
 872         spin_lock(&sbi->inode_hash_lock);
 873         if (i_pos != MSDOS_I(inode)->i_pos) {
 874                 spin_unlock(&sbi->inode_hash_lock);
 875                 brelse(bh);
 876                 goto retry;
 877         }
 878
 879         raw_entry = &((struct msdos_dir_entry *) (bh->b_data))[offset];
 880         if (S_ISDIR(inode->i_mode))
 881                 raw_entry->size = 0;
 882         else
 883                 raw_entry->size = cpu_to_le32(inode->i_size);
 884         raw_entry->attr = fat_make_attrs(inode);
 885         fat_set_start(raw_entry, MSDOS_I(inode)->i_logstart);
 886         fat_time_unix2fat(sbi, &inode->i_mtime, &raw_entry->time,
 887                           &raw_entry->date, NULL);
 888         if (sbi->options.isvfat) {
 889                 __le16 atime;
 890                 fat_time_unix2fat(sbi, &inode->i_ctime, &raw_entry->ctime,
 891                                   &raw_entry->cdate, &raw_entry->ctime_cs);
 892                 fat_time_unix2fat(sbi, &inode->i_atime, &atime,
 893                                   &raw_entry->adate, NULL);
 894         }
 895         spin_unlock(&sbi->inode_hash_lock);
 896         mark_buffer_dirty(bh);
 897         err = 0;
 898         if (wait)
 899                 err = sync_dirty_buffer(bh);
 900         brelse(bh);
 901         return err;
 902 }
 903
 904 static int fat_write_inode(struct inode *inode, struct writeback_control *wbc)
 905 {
 906         int err;
 907
 908         if (inode->i_ino == MSDOS_FSINFO_INO) {
 909                 struct super_block *sb = inode->i_sb;
 910
 911                 mutex_lock(&MSDOS_SB(sb)->s_lock);
 912                 err = fat_clusters_flush(sb);
 913                 mutex_unlock(&MSDOS_SB(sb)->s_lock);
 914         } else
 915                 err = __fat_write_inode(inode, wbc->sync_mode == WB_SYNC_ALL);
 916
 917         return err;
 918 }
 919
 920 int fat_sync_inode(struct inode *inode)
 921 {
 922         return __fat_write_inode(inode, 1);
 923 }
 924
 925 EXPORT_SYMBOL_GPL(fat_sync_inode);
 926
 927 static int fat_show_options(struct seq_file *m, struct dentry *root);
 928 static const struct super_operations fat_sops = {
 929         .alloc_inode    = fat_alloc_inode,
 930         .destroy_inode  = fat_destroy_inode,
 931         .write_inode    = fat_write_inode,
 932         .evict_inode    = fat_evict_inode,
 933         .put_super      = fat_put_super,
 934         .statfs         = fat_statfs,
 935         .remount_fs     = fat_remount,
 936
 937         .show_options   = fat_show_options,
 938 };
 939
 940 static int fat_show_options(struct seq_file *m, struct dentry *root)
 941 {
 942         struct msdos_sb_info *sbi = MSDOS_SB(root->d_sb);
 943         struct fat_mount_options *opts = &sbi->options;
 944         int isvfat = opts->isvfat;
 945
 946         if (!uid_eq(opts->fs_uid, GLOBAL_ROOT_UID))
 947                 seq_printf(m, ",uid=%u",
 948                                 from_kuid_munged(&init_user_ns, opts->fs_uid));
 949         if (!gid_eq(opts->fs_gid, GLOBAL_ROOT_GID))
 950                 seq_printf(m, ",gid=%u",
 951                                 from_kgid_munged(&init_user_ns, opts->fs_gid));
 952         seq_printf(m, ",fmask=%04o", opts->fs_fmask);
 953         seq_printf(m, ",dmask=%04o", opts->fs_dmask);
 954         if (opts->allow_utime)
 955                 seq_printf(m, ",allow_utime=%04o", opts->allow_utime);
 956         if (sbi->nls_disk)
 957                 /* strip "cp" prefix from displayed option */
 958                 seq_printf(m, ",codepage=%s", &sbi->nls_disk->charset[2]);
 959         if (isvfat) {
 960                 if (sbi->nls_io)
 961                         seq_printf(m, ",iocharset=%s", sbi->nls_io->charset);
 962
 963                 switch (opts->shortname) {
 964                 case VFAT_SFN_DISPLAY_WIN95 | VFAT_SFN_CREATE_WIN95:
 965                         seq_puts(m, ",shortname=win95");
 966                         break;
 967                 case VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WINNT:
 968                         seq_puts(m, ",shortname=winnt");
 969                         break;
 970                 case VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WIN95:
 971                         seq_puts(m, ",shortname=mixed");
 972                         break;
 973                 case VFAT_SFN_DISPLAY_LOWER | VFAT_SFN_CREATE_WIN95:
 974                         seq_puts(m, ",shortname=lower");
 975                         break;
 976                 default:
 977                         seq_puts(m, ",shortname=unknown");
 978                         break;
 979                 }
 980         }
 981         if (opts->name_check != 'n')
 982                 seq_printf(m, ",check=%c", opts->name_check);
 983         if (opts->usefree)
 984                 seq_puts(m, ",usefree");
 985         if (opts->quiet)
 986                 seq_puts(m, ",quiet");
 987         if (opts->showexec)
 988                 seq_puts(m, ",showexec");
 989         if (opts->sys_immutable)
 990                 seq_puts(m, ",sys_immutable");
 991         if (!isvfat) {
 992                 if (opts->dotsOK)
 993                         seq_puts(m, ",dotsOK=yes");
 994                 if (opts->nocase)
 995                         seq_puts(m, ",nocase");
 996         } else {
 997                 if (opts->utf8)
 998                         seq_puts(m, ",utf8");
 999                 if (opts->unicode_xlate)
1000                         seq_puts(m, ",uni_xlate");
1001                 if (!opts->numtail)
1002                         seq_puts(m, ",nonumtail");
1003                 if (opts->rodir)
1004                         seq_puts(m, ",rodir");
1005         }
1006         if (opts->flush)
1007                 seq_puts(m, ",flush");
1008         if (opts->tz_set) {
1009                 if (opts->time_offset)
1010                         seq_printf(m, ",time_offset=%d", opts->time_offset);
1011                 else
1012                         seq_puts(m, ",tz=UTC");
1013         }
1014         if (opts->errors == FAT_ERRORS_CONT)
1015                 seq_puts(m, ",errors=continue");
1016         else if (opts->errors == FAT_ERRORS_PANIC)
1017                 seq_puts(m, ",errors=panic");
1018         else
1019                 seq_puts(m, ",errors=remount-ro");
1020         if (opts->nfs == FAT_NFS_NOSTALE_RO)
1021                 seq_puts(m, ",nfs=nostale_ro");
1022         else if (opts->nfs)
1023                 seq_puts(m, ",nfs=stale_rw");
1024         if (opts->discard)
1025                 seq_puts(m, ",discard");
1026         if (opts->dos1xfloppy)
1027                 seq_puts(m, ",dos1xfloppy");
1028
1029         return 0;
1030 }
1031
1032 enum {
1033         Opt_check_n, Opt_check_r, Opt_check_s, Opt_uid, Opt_gid,
1034         Opt_umask, Opt_dmask, Opt_fmask, Opt_allow_utime, Opt_codepage,
1035         Opt_usefree, Opt_nocase, Opt_quiet, Opt_showexec, Opt_debug,
1036         Opt_immutable, Opt_dots, Opt_nodots,
1037         Opt_charset, Opt_shortname_lower, Opt_shortname_win95,
1038         Opt_shortname_winnt, Opt_shortname_mixed, Opt_utf8_no, Opt_utf8_yes,
1039         Opt_uni_xl_no, Opt_uni_xl_yes, Opt_nonumtail_no, Opt_nonumtail_yes,
1040         Opt_obsolete, Opt_flush, Opt_tz_utc, Opt_rodir, Opt_err_cont,
1041         Opt_err_panic, Opt_err_ro, Opt_discard, Opt_nfs, Opt_time_offset,
1042         Opt_nfs_stale_rw, Opt_nfs_nostale_ro, Opt_err, Opt_dos1xfloppy,
1043 };
1044
1045 static const match_table_t fat_tokens = {
1046         {Opt_check_r, "check=relaxed"},
1047         {Opt_check_s, "check=strict"},
1048         {Opt_check_n, "check=normal"},
1049         {Opt_check_r, "check=r"},
1050         {Opt_check_s, "check=s"},
1051         {Opt_check_n, "check=n"},
1052         {Opt_uid, "uid=%u"},
1053         {Opt_gid, "gid=%u"},
1054         {Opt_umask, "umask=%o"},
1055         {Opt_dmask, "dmask=%o"},
1056         {Opt_fmask, "fmask=%o"},
1057         {Opt_allow_utime, "allow_utime=%o"},
1058         {Opt_codepage, "codepage=%u"},
1059         {Opt_usefree, "usefree"},
1060         {Opt_nocase, "nocase"},
1061         {Opt_quiet, "quiet"},
1062         {Opt_showexec, "showexec"},
1063         {Opt_debug, "debug"},
1064         {Opt_immutable, "sys_immutable"},
1065         {Opt_flush, "flush"},
1066         {Opt_tz_utc, "tz=UTC"},
1067         {Opt_time_offset, "time_offset=%d"},
1068         {Opt_err_cont, "errors=continue"},
1069         {Opt_err_panic, "errors=panic"},
1070         {Opt_err_ro, "errors=remount-ro"},
1071         {Opt_discard, "discard"},
1072         {Opt_nfs_stale_rw, "nfs"},
1073         {Opt_nfs_stale_rw, "nfs=stale_rw"},
1074         {Opt_nfs_nostale_ro, "nfs=nostale_ro"},
1075         {Opt_dos1xfloppy, "dos1xfloppy"},
1076         {Opt_obsolete, "conv=binary"},
1077         {Opt_obsolete, "conv=text"},
1078         {Opt_obsolete, "conv=auto"},
1079         {Opt_obsolete, "conv=b"},
1080         {Opt_obsolete, "conv=t"},
1081         {Opt_obsolete, "conv=a"},
1082         {Opt_obsolete, "fat=%u"},
1083         {Opt_obsolete, "blocksize=%u"},
1084         {Opt_obsolete, "cvf_format=%20s"},
1085         {Opt_obsolete, "cvf_options=%100s"},
1086         {Opt_obsolete, "posix"},
1087         {Opt_err, NULL},
1088 };
1089 static const match_table_t msdos_tokens = {
1090         {Opt_nodots, "nodots"},
1091         {Opt_nodots, "dotsOK=no"},
1092         {Opt_dots, "dots"},
1093         {Opt_dots, "dotsOK=yes"},
1094         {Opt_err, NULL}
1095 };
1096 static const match_table_t vfat_tokens = {
1097         {Opt_charset, "iocharset=%s"},
1098         {Opt_shortname_lower, "shortname=lower"},
1099         {Opt_shortname_win95, "shortname=win95"},
1100         {Opt_shortname_winnt, "shortname=winnt"},
1101         {Opt_shortname_mixed, "shortname=mixed"},
1102         {Opt_utf8_no, "utf8=0"},                /* 0 or no or false */
1103         {Opt_utf8_no, "utf8=no"},
1104         {Opt_utf8_no, "utf8=false"},
1105         {Opt_utf8_yes, "utf8=1"},               /* empty or 1 or yes or true */
1106         {Opt_utf8_yes, "utf8=yes"},
1107         {Opt_utf8_yes, "utf8=true"},
1108         {Opt_utf8_yes, "utf8"},
1109         {Opt_uni_xl_no, "uni_xlate=0"},         /* 0 or no or false */
1110         {Opt_uni_xl_no, "uni_xlate=no"},
1111         {Opt_uni_xl_no, "uni_xlate=false"},
1112         {Opt_uni_xl_yes, "uni_xlate=1"},        /* empty or 1 or yes or true */
1113         {Opt_uni_xl_yes, "uni_xlate=yes"},
1114         {Opt_uni_xl_yes, "uni_xlate=true"},
1115         {Opt_uni_xl_yes, "uni_xlate"},
1116         {Opt_nonumtail_no, "nonumtail=0"},      /* 0 or no or false */
1117         {Opt_nonumtail_no, "nonumtail=no"},
1118         {Opt_nonumtail_no, "nonumtail=false"},
1119         {Opt_nonumtail_yes, "nonumtail=1"},     /* empty or 1 or yes or true */
1120         {Opt_nonumtail_yes, "nonumtail=yes"},
1121         {Opt_nonumtail_yes, "nonumtail=true"},
1122         {Opt_nonumtail_yes, "nonumtail"},
1123         {Opt_rodir, "rodir"},
1124         {Opt_err, NULL}
1125 };
1126
1127 static int parse_options(struct super_block *sb, char *options, int is_vfat,
1128                          int silent, int *debug, struct fat_mount_options *opts)
1129 {
1130         char *p;
1131         substring_t args[MAX_OPT_ARGS];
1132         int option;
1133         char *iocharset;
1134
1135         opts->isvfat = is_vfat;
1136
1137         opts->fs_uid = current_uid();
1138         opts->fs_gid = current_gid();
1139         opts->fs_fmask = opts->fs_dmask = current_umask();
1140         opts->allow_utime = -1;
1141         opts->codepage = fat_default_codepage;
1142         fat_reset_iocharset(opts);
1143         if (is_vfat) {
1144                 opts->shortname = VFAT_SFN_DISPLAY_WINNT|VFAT_SFN_CREATE_WIN95;
1145                 opts->rodir = 0;
1146         } else {
1147                 opts->shortname = 0;
1148                 opts->rodir = 1;
1149         }
1150         opts->name_check = 'n';
1151         opts->quiet = opts->showexec = opts->sys_immutable = opts->dotsOK =  0;
1152         opts->unicode_xlate = 0;
1153         opts->numtail = 1;
1154         opts->usefree = opts->nocase = 0;
1155         opts->tz_set = 0;
1156         opts->nfs = 0;
1157         opts->errors = FAT_ERRORS_RO;
1158         *debug = 0;
1159
1160         opts->utf8 = IS_ENABLED(CONFIG_FAT_DEFAULT_UTF8) && is_vfat;
1161
1162         if (!options)
1163                 goto out;
1164
1165         while ((p = strsep(&options, ",")) != NULL) {
1166                 int token;
1167                 if (!*p)
1168                         continue;
1169
1170                 token = match_token(p, fat_tokens, args);
1171                 if (token == Opt_err) {
1172                         if (is_vfat)
1173                                 token = match_token(p, vfat_tokens, args);
1174                         else
1175                                 token = match_token(p, msdos_tokens, args);
1176                 }
1177                 switch (token) {
1178                 case Opt_check_s:
1179                         opts->name_check = 's';
1180                         break;
1181                 case Opt_check_r:
1182                         opts->name_check = 'r';
1183                         break;
1184                 case Opt_check_n:
1185                         opts->name_check = 'n';
1186                         break;
1187                 case Opt_usefree:
1188                         opts->usefree = 1;
1189                         break;
1190                 case Opt_nocase:
1191                         if (!is_vfat)
1192                                 opts->nocase = 1;
1193                         else {
1194                                 /* for backward compatibility */
1195                                 opts->shortname = VFAT_SFN_DISPLAY_WIN95
1196                                         | VFAT_SFN_CREATE_WIN95;
1197                         }
1198                         break;
1199                 case Opt_quiet:
1200                         opts->quiet = 1;
1201                         break;
1202                 case Opt_showexec:
1203                         opts->showexec = 1;
1204                         break;
1205                 case Opt_debug:
1206                         *debug = 1;
1207                         break;
1208                 case Opt_immutable:
1209                         opts->sys_immutable = 1;
1210                         break;
1211                 case Opt_uid:
1212                         if (match_int(&args[0], &option))
1213                                 return -EINVAL;
1214                         opts->fs_uid = make_kuid(current_user_ns(), option);
1215                         if (!uid_valid(opts->fs_uid))
1216                                 return -EINVAL;
1217                         break;
1218                 case Opt_gid:
1219                         if (match_int(&args[0], &option))
1220                                 return -EINVAL;
1221                         opts->fs_gid = make_kgid(current_user_ns(), option);
1222                         if (!gid_valid(opts->fs_gid))
1223                                 return -EINVAL;
1224                         break;
1225                 case Opt_umask:
1226                         if (match_octal(&args[0], &option))
1227                                 return -EINVAL;
1228                         opts->fs_fmask = opts->fs_dmask = option;
1229                         break;
1230                 case Opt_dmask:
1231                         if (match_octal(&args[0], &option))
1232                                 return -EINVAL;
1233                         opts->fs_dmask = option;
1234                         break;
1235                 case Opt_fmask:
1236                         if (match_octal(&args[0], &option))
1237                                 return -EINVAL;
1238                         opts->fs_fmask = option;
1239                         break;
1240                 case Opt_allow_utime:
1241                         if (match_octal(&args[0], &option))
1242                                 return -EINVAL;
1243                         opts->allow_utime = option & (S_IWGRP | S_IWOTH);
1244                         break;
1245                 case Opt_codepage:
1246                         if (match_int(&args[0], &option))
1247                                 return -EINVAL;
1248                         opts->codepage = option;
1249                         break;
1250                 case Opt_flush:
1251                         opts->flush = 1;
1252                         break;
1253                 case Opt_time_offset:
1254                         if (match_int(&args[0], &option))
1255                                 return -EINVAL;
1256                         /*
1257                          * GMT+-12 zones may have DST corrections so at least
1258                          * 13 hours difference is needed. Make the limit 24
1259                          * just in case someone invents something unusual.
1260                          */
1261                         if (option < -24 * 60 || option > 24 * 60)
1262                                 return -EINVAL;
1263                         opts->tz_set = 1;
1264                         opts->time_offset = option;
1265                         break;
1266                 case Opt_tz_utc:
1267                         opts->tz_set = 1;
1268                         opts->time_offset = 0;
1269                         break;
1270                 case Opt_err_cont:
1271                         opts->errors = FAT_ERRORS_CONT;
1272                         break;
1273                 case Opt_err_panic:
1274                         opts->errors = FAT_ERRORS_PANIC;
1275                         break;
1276                 case Opt_err_ro:
1277                         opts->errors = FAT_ERRORS_RO;
1278                         break;
1279                 case Opt_nfs_stale_rw:
1280                         opts->nfs = FAT_NFS_STALE_RW;
1281                         break;
1282                 case Opt_nfs_nostale_ro:
1283                         opts->nfs = FAT_NFS_NOSTALE_RO;
1284                         break;
1285                 case Opt_dos1xfloppy:
1286                         opts->dos1xfloppy = 1;
1287                         break;
1288
1289                 /* msdos specific */
1290                 case Opt_dots:
1291                         opts->dotsOK = 1;
1292                         break;
1293                 case Opt_nodots:
1294                         opts->dotsOK = 0;
1295                         break;
1296
1297                 /* vfat specific */
1298                 case Opt_charset:
1299                         fat_reset_iocharset(opts);
1300                         iocharset = match_strdup(&args[0]);
1301                         if (!iocharset)
1302                                 return -ENOMEM;
1303                         opts->iocharset = iocharset;
1304                         break;
1305                 case Opt_shortname_lower:
1306                         opts->shortname = VFAT_SFN_DISPLAY_LOWER
1307                                         | VFAT_SFN_CREATE_WIN95;
1308                         break;
1309                 case Opt_shortname_win95:
1310                         opts->shortname = VFAT_SFN_DISPLAY_WIN95
1311                                         | VFAT_SFN_CREATE_WIN95;
1312                         break;
1313                 case Opt_shortname_winnt:
1314                         opts->shortname = VFAT_SFN_DISPLAY_WINNT
1315                                         | VFAT_SFN_CREATE_WINNT;
1316                         break;
1317                 case Opt_shortname_mixed:
1318                         opts->shortname = VFAT_SFN_DISPLAY_WINNT
1319                                         | VFAT_SFN_CREATE_WIN95;
1320                         break;
1321                 case Opt_utf8_no:               /* 0 or no or false */
1322                         opts->utf8 = 0;
1323                         break;
1324                 case Opt_utf8_yes:              /* empty or 1 or yes or true */
1325                         opts->utf8 = 1;
1326                         break;
1327                 case Opt_uni_xl_no:             /* 0 or no or false */
1328                         opts->unicode_xlate = 0;
1329                         break;
1330                 case Opt_uni_xl_yes:            /* empty or 1 or yes or true */
1331                         opts->unicode_xlate = 1;
1332                         break;
1333                 case Opt_nonumtail_no:          /* 0 or no or false */
1334                         opts->numtail = 1;      /* negated option */
1335                         break;
1336                 case Opt_nonumtail_yes:         /* empty or 1 or yes or true */
1337                         opts->numtail = 0;      /* negated option */
1338                         break;
1339                 case Opt_rodir:
1340                         opts->rodir = 1;
1341                         break;
1342                 case Opt_discard:
1343                         opts->discard = 1;
1344                         break;
1345
1346                 /* obsolete mount options */
1347                 case Opt_obsolete:
1348                         fat_msg(sb, KERN_INFO, "\"%s\" option is obsolete, "
1349                                "not supported now", p);
1350                         break;
1351                 /* unknown option */
1352                 default:
1353                         if (!silent) {
1354                                 fat_msg(sb, KERN_ERR,
1355                                        "Unrecognized mount option \"%s\" "
1356                                        "or missing value", p);
1357                         }
1358                         return -EINVAL;
1359                 }
1360         }
1361
1362 out:
1363         /* UTF-8 doesn't provide FAT semantics */
1364         if (!strcmp(opts->iocharset, "utf8")) {
1365                 fat_msg(sb, KERN_WARNING, "utf8 is not a recommended IO charset"
1366                        " for FAT filesystems, filesystem will be "
1367                        "case sensitive!");
1368         }
1369
1370         /* If user doesn't specify allow_utime, it's initialized from dmask. */
1371         if (opts->allow_utime == (unsigned short)-1)
1372                 opts->allow_utime = ~opts->fs_dmask & (S_IWGRP | S_IWOTH);
1373         if (opts->unicode_xlate)
1374                 opts->utf8 = 0;
1375         if (opts->nfs == FAT_NFS_NOSTALE_RO) {
1376                 sb->s_flags |= SB_RDONLY;
1377                 sb->s_export_op = &fat_export_ops_nostale;
1378         }
1379
1380         return 0;
1381 }
1382
1383 static int fat_read_root(struct inode *inode)
1384 {
1385         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
1386         int error;
1387
1388         MSDOS_I(inode)->i_pos = MSDOS_ROOT_INO;
1389         inode->i_uid = sbi->options.fs_uid;
1390         inode->i_gid = sbi->options.fs_gid;
1391         inode_inc_iversion(inode);
1392         inode->i_generation = 0;
1393         inode->i_mode = fat_make_mode(sbi, ATTR_DIR, S_IRWXUGO);
1394         inode->i_op = sbi->dir_ops;
1395         inode->i_fop = &fat_dir_operations;
1396         if (sbi->fat_bits == 32) {
1397                 MSDOS_I(inode)->i_start = sbi->root_cluster;
1398                 error = fat_calc_dir_size(inode);
1399                 if (error < 0)
1400                         return error;
1401         } else {
1402                 MSDOS_I(inode)->i_start = 0;
1403                 inode->i_size = sbi->dir_entries * sizeof(struct msdos_dir_entry);
1404         }
1405         inode->i_blocks = ((inode->i_size + (sbi->cluster_size - 1))
1406                            & ~((loff_t)sbi->cluster_size - 1)) >> 9;
1407         MSDOS_I(inode)->i_logstart = 0;
1408         MSDOS_I(inode)->mmu_private = inode->i_size;
1409
1410         fat_save_attrs(inode, ATTR_DIR);
1411         inode->i_mtime.tv_sec = inode->i_atime.tv_sec = inode->i_ctime.tv_sec = 0;
1412         inode->i_mtime.tv_nsec = inode->i_atime.tv_nsec = inode->i_ctime.tv_nsec = 0;
1413         set_nlink(inode, fat_subdirs(inode)+2);
1414
1415         return 0;
1416 }
1417
1418 static unsigned long calc_fat_clusters(struct super_block *sb)
1419 {
1420         struct msdos_sb_info *sbi = MSDOS_SB(sb);
1421
1422         /* Divide first to avoid overflow */
1423         if (sbi->fat_bits != 12) {
1424                 unsigned long ent_per_sec = sb->s_blocksize * 8 / sbi->fat_bits;
1425                 return ent_per_sec * sbi->fat_length;
1426         }
1427
1428         return sbi->fat_length * sb->s_blocksize * 8 / sbi->fat_bits;
1429 }
1430
1431 static bool fat_bpb_is_zero(struct fat_boot_sector *b)
1432 {
1433         if (get_unaligned_le16(&b->sector_size))
1434                 return false;
1435         if (b->sec_per_clus)
1436                 return false;
1437         if (b->reserved)
1438                 return false;
1439         if (b->fats)
1440                 return false;
1441         if (get_unaligned_le16(&b->dir_entries))
1442                 return false;
1443         if (get_unaligned_le16(&b->sectors))
1444                 return false;
1445         if (b->media)
1446                 return false;
1447         if (b->fat_length)
1448                 return false;
1449         if (b->secs_track)
1450                 return false;
1451         if (b->heads)
1452                 return false;
1453         return true;
1454 }
1455
1456 static int fat_read_bpb(struct super_block *sb, struct fat_boot_sector *b,
1457         int silent, struct fat_bios_param_block *bpb)
1458 {
1459         int error = -EINVAL;
1460
1461         /* Read in BPB ... */
1462         memset(bpb, 0, sizeof(*bpb));
1463         bpb->fat_sector_size = get_unaligned_le16(&b->sector_size);
1464         bpb->fat_sec_per_clus = b->sec_per_clus;
1465         bpb->fat_reserved = le16_to_cpu(b->reserved);
1466         bpb->fat_fats = b->fats;
1467         bpb->fat_dir_entries = get_unaligned_le16(&b->dir_entries);
1468         bpb->fat_sectors = get_unaligned_le16(&b->sectors);
1469         bpb->fat_fat_length = le16_to_cpu(b->fat_length);
1470         bpb->fat_total_sect = le32_to_cpu(b->total_sect);
1471
1472         bpb->fat16_state = b->fat16.state;
1473         bpb->fat16_vol_id = get_unaligned_le32(b->fat16.vol_id);
1474
1475         bpb->fat32_length = le32_to_cpu(b->fat32.length);
1476         bpb->fat32_root_cluster = le32_to_cpu(b->fat32.root_cluster);
1477         bpb->fat32_info_sector = le16_to_cpu(b->fat32.info_sector);
1478         bpb->fat32_state = b->fat32.state;
1479         bpb->fat32_vol_id = get_unaligned_le32(b->fat32.vol_id);
1480
1481         /* Validate this looks like a FAT filesystem BPB */
1482         if (!bpb->fat_reserved) {
1483                 if (!silent)
1484                         fat_msg(sb, KERN_ERR,
1485                                 "bogus number of reserved sectors");
1486                 goto out;
1487         }
1488         if (!bpb->fat_fats) {
1489                 if (!silent)
1490                         fat_msg(sb, KERN_ERR, "bogus number of FAT structure");
1491                 goto out;
1492         }
1493
1494         /*
1495          * Earlier we checked here that b->secs_track and b->head are nonzero,
1496          * but it turns out valid FAT filesystems can have zero there.
1497          */
1498
1499         if (!fat_valid_media(b->media)) {
1500                 if (!silent)
1501                         fat_msg(sb, KERN_ERR, "invalid media value (0x%02x)",
1502                                 (unsigned)b->media);
1503                 goto out;
1504         }
1505
1506         if (!is_power_of_2(bpb->fat_sector_size)
1507             || (bpb->fat_sector_size < 512)
1508             || (bpb->fat_sector_size > 4096)) {
1509                 if (!silent)
1510                         fat_msg(sb, KERN_ERR, "bogus logical sector size %u",
1511                                (unsigned)bpb->fat_sector_size);
1512                 goto out;
1513         }
1514
1515         if (!is_power_of_2(bpb->fat_sec_per_clus)) {
1516                 if (!silent)
1517                         fat_msg(sb, KERN_ERR, "bogus sectors per cluster %u",
1518                                 (unsigned)bpb->fat_sec_per_clus);
1519                 goto out;
1520         }
1521
1522         if (bpb->fat_fat_length == 0 && bpb->fat32_length == 0) {
1523                 if (!silent)
1524                         fat_msg(sb, KERN_ERR, "bogus number of FAT sectors");
1525                 goto out;
1526         }
1527
1528         error = 0;
1529
1530 out:
1531         return error;
1532 }
1533
1534 static int fat_read_static_bpb(struct super_block *sb,
1535         struct fat_boot_sector *b, int silent,
1536         struct fat_bios_param_block *bpb)
1537 {
1538         static const char *notdos1x = "This doesn't look like a DOS 1.x volume";
1539
1540         struct fat_floppy_defaults *fdefaults = NULL;
1541         int error = -EINVAL;
1542         sector_t bd_sects;
1543         unsigned i;
1544
1545         bd_sects = i_size_read(sb->s_bdev->bd_inode) / SECTOR_SIZE;
1546
1547         /* 16-bit DOS 1.x reliably wrote bootstrap short-jmp code */
1548         if (b->ignored[0] != 0xeb || b->ignored[2] != 0x90) {
1549                 if (!silent)
1550                         fat_msg(sb, KERN_ERR,
1551                                 "%s; no bootstrapping code", notdos1x);
1552                 goto out;
1553         }
1554
1555         /*
1556          * If any value in this region is non-zero, it isn't archaic
1557          * DOS.
1558          */
1559         if (!fat_bpb_is_zero(b)) {
1560                 if (!silent)
1561                         fat_msg(sb, KERN_ERR,
1562                                 "%s; DOS 2.x BPB is non-zero", notdos1x);
1563                 goto out;
1564         }
1565
1566         for (i = 0; i < ARRAY_SIZE(floppy_defaults); i++) {
1567                 if (floppy_defaults[i].nr_sectors == bd_sects) {
1568                         fdefaults = &floppy_defaults[i];
1569                         break;
1570                 }
1571         }
1572
1573         if (fdefaults == NULL) {
1574                 if (!silent)
1575                         fat_msg(sb, KERN_WARNING,
1576                                 "This looks like a DOS 1.x volume, but isn't a recognized floppy size (%llu sectors)",
1577                                 (u64)bd_sects);
1578                 goto out;
1579         }
1580
1581         if (!silent)
1582                 fat_msg(sb, KERN_INFO,
1583                         "This looks like a DOS 1.x volume; assuming default BPB values");
1584
1585         memset(bpb, 0, sizeof(*bpb));
1586         bpb->fat_sector_size = SECTOR_SIZE;
1587         bpb->fat_sec_per_clus = fdefaults->sec_per_clus;
1588         bpb->fat_reserved = 1;
1589         bpb->fat_fats = 2;
1590         bpb->fat_dir_entries = fdefaults->dir_entries;
1591         bpb->fat_sectors = fdefaults->nr_sectors;
1592         bpb->fat_fat_length = fdefaults->fat_length;
1593
1594         error = 0;
1595
1596 out:
1597         return error;
1598 }
1599
1600 /*
1601  * Read the super block of an MS-DOS FS.
1602  */
1603 int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat,
1604                    void (*setup)(struct super_block *))
1605 {
1606         struct inode *root_inode = NULL, *fat_inode = NULL;
1607         struct inode *fsinfo_inode = NULL;
1608         struct buffer_head *bh;
1609         struct fat_bios_param_block bpb;
1610         struct msdos_sb_info *sbi;
1611         u16 logical_sector_size;
1612         u32 total_sectors, total_clusters, fat_clusters, rootdir_sectors;
1613         int debug;
1614         long error;
1615         char buf[50];
1616
1617         /*
1618          * GFP_KERNEL is ok here, because while we do hold the
1619          * superblock lock, memory pressure can't call back into
1620          * the filesystem, since we're only just about to mount
1621          * it and have no inodes etc active!
1622          */
1623         sbi = kzalloc(sizeof(struct msdos_sb_info), GFP_KERNEL);
1624         if (!sbi)
1625                 return -ENOMEM;
1626         sb->s_fs_info = sbi;
1627
1628         sb->s_flags |= SB_NODIRATIME;
1629         sb->s_magic = MSDOS_SUPER_MAGIC;
1630         sb->s_op = &fat_sops;
1631         sb->s_export_op = &fat_export_ops;
1632         mutex_init(&sbi->nfs_build_inode_lock);
1633         ratelimit_state_init(&sbi->ratelimit, DEFAULT_RATELIMIT_INTERVAL,
1634                              DEFAULT_RATELIMIT_BURST);
1635
1636         error = parse_options(sb, data, isvfat, silent, &debug, &sbi->options);
1637         if (error)
1638                 goto out_fail;
1639
1640         setup(sb); /* flavour-specific stuff that needs options */
1641
1642         error = -EIO;
1643         sb_min_blocksize(sb, 512);
1644         bh = sb_bread(sb, 0);
1645         if (bh == NULL) {
1646                 fat_msg(sb, KERN_ERR, "unable to read boot sector");
1647                 goto out_fail;
1648         }
1649
1650         error = fat_read_bpb(sb, (struct fat_boot_sector *)bh->b_data, silent,
1651                 &bpb);
1652         if (error == -EINVAL && sbi->options.dos1xfloppy)
1653                 error = fat_read_static_bpb(sb,
1654                         (struct fat_boot_sector *)bh->b_data, silent, &bpb);
1655         brelse(bh);
1656
1657         if (error == -EINVAL)
1658                 goto out_invalid;
1659         else if (error)
1660                 goto out_fail;
1661
1662         logical_sector_size = bpb.fat_sector_size;
1663         sbi->sec_per_clus = bpb.fat_sec_per_clus;
1664
1665         error = -EIO;
1666         if (logical_sector_size < sb->s_blocksize) {
1667                 fat_msg(sb, KERN_ERR, "logical sector size too small for device"
1668                        " (logical sector size = %u)", logical_sector_size);
1669                 goto out_fail;
1670         }
1671
1672         if (logical_sector_size > sb->s_blocksize) {
1673                 struct buffer_head *bh_resize;
1674
1675                 if (!sb_set_blocksize(sb, logical_sector_size)) {
1676                         fat_msg(sb, KERN_ERR, "unable to set blocksize %u",
1677                                logical_sector_size);
1678                         goto out_fail;
1679                 }
1680
1681                 /* Verify that the larger boot sector is fully readable */
1682                 bh_resize = sb_bread(sb, 0);
1683                 if (bh_resize == NULL) {
1684                         fat_msg(sb, KERN_ERR, "unable to read boot sector"
1685                                " (logical sector size = %lu)",
1686                                sb->s_blocksize);
1687                         goto out_fail;
1688                 }
1689                 brelse(bh_resize);
1690         }
1691
1692         mutex_init(&sbi->s_lock);
1693         sbi->cluster_size = sb->s_blocksize * sbi->sec_per_clus;
1694         sbi->cluster_bits = ffs(sbi->cluster_size) - 1;
1695         sbi->fats = bpb.fat_fats;
1696         sbi->fat_bits = 0;              /* Don't know yet */
1697         sbi->fat_start = bpb.fat_reserved;
1698         sbi->fat_length = bpb.fat_fat_length;
1699         sbi->root_cluster = 0;
1700         sbi->free_clusters = -1;        /* Don't know yet */
1701         sbi->free_clus_valid = 0;
1702         sbi->prev_free = FAT_START_ENT;
1703         sb->s_maxbytes = 0xffffffff;
1704
1705         if (!sbi->fat_length && bpb.fat32_length) {
1706                 struct fat_boot_fsinfo *fsinfo;
1707                 struct buffer_head *fsinfo_bh;
1708
1709                 /* Must be FAT32 */
1710                 sbi->fat_bits = 32;
1711                 sbi->fat_length = bpb.fat32_length;
1712                 sbi->root_cluster = bpb.fat32_root_cluster;
1713
1714                 /* MC - if info_sector is 0, don't multiply by 0 */
1715                 sbi->fsinfo_sector = bpb.fat32_info_sector;
1716                 if (sbi->fsinfo_sector == 0)
1717                         sbi->fsinfo_sector = 1;
1718
1719                 fsinfo_bh = sb_bread(sb, sbi->fsinfo_sector);
1720                 if (fsinfo_bh == NULL) {
1721                         fat_msg(sb, KERN_ERR, "bread failed, FSINFO block"
1722                                " (sector = %lu)", sbi->fsinfo_sector);
1723                         goto out_fail;
1724                 }
1725
1726                 fsinfo = (struct fat_boot_fsinfo *)fsinfo_bh->b_data;
1727                 if (!IS_FSINFO(fsinfo)) {
1728                         fat_msg(sb, KERN_WARNING, "Invalid FSINFO signature: "
1729                                "0x%08x, 0x%08x (sector = %lu)",
1730                                le32_to_cpu(fsinfo->signature1),
1731                                le32_to_cpu(fsinfo->signature2),
1732                                sbi->fsinfo_sector);
1733                 } else {
1734                         if (sbi->options.usefree)
1735                                 sbi->free_clus_valid = 1;
1736                         sbi->free_clusters = le32_to_cpu(fsinfo->free_clusters);
1737                         sbi->prev_free = le32_to_cpu(fsinfo->next_cluster);
1738                 }
1739
1740                 brelse(fsinfo_bh);
1741         }
1742
1743         /* interpret volume ID as a little endian 32 bit integer */
1744         if (sbi->fat_bits == 32)
1745                 sbi->vol_id = bpb.fat32_vol_id;
1746         else /* fat 16 or 12 */
1747                 sbi->vol_id = bpb.fat16_vol_id;
1748
1749         sbi->dir_per_block = sb->s_blocksize / sizeof(struct msdos_dir_entry);
1750         sbi->dir_per_block_bits = ffs(sbi->dir_per_block) - 1;
1751
1752         sbi->dir_start = sbi->fat_start + sbi->fats * sbi->fat_length;
1753         sbi->dir_entries = bpb.fat_dir_entries;
1754         if (sbi->dir_entries & (sbi->dir_per_block - 1)) {
1755                 if (!silent)
1756                         fat_msg(sb, KERN_ERR, "bogus number of directory entries"
1757                                " (%u)", sbi->dir_entries);
1758                 goto out_invalid;
1759         }
1760
1761         rootdir_sectors = sbi->dir_entries
1762                 * sizeof(struct msdos_dir_entry) / sb->s_blocksize;
1763         sbi->data_start = sbi->dir_start + rootdir_sectors;
1764         total_sectors = bpb.fat_sectors;
1765         if (total_sectors == 0)
1766                 total_sectors = bpb.fat_total_sect;
1767
1768         total_clusters = (total_sectors - sbi->data_start) / sbi->sec_per_clus;
1769
1770         if (sbi->fat_bits != 32)
1771                 sbi->fat_bits = (total_clusters > MAX_FAT12) ? 16 : 12;
1772
1773         /* some OSes set FAT_STATE_DIRTY and clean it on unmount. */
1774         if (sbi->fat_bits == 32)
1775                 sbi->dirty = bpb.fat32_state & FAT_STATE_DIRTY;
1776         else /* fat 16 or 12 */
1777                 sbi->dirty = bpb.fat16_state & FAT_STATE_DIRTY;
1778
1779         /* check that FAT table does not overflow */
1780         fat_clusters = calc_fat_clusters(sb);
1781         total_clusters = min(total_clusters, fat_clusters - FAT_START_ENT);
1782         if (total_clusters > MAX_FAT(sb)) {
1783                 if (!silent)
1784                         fat_msg(sb, KERN_ERR, "count of clusters too big (%u)",
1785                                total_clusters);
1786                 goto out_invalid;
1787         }
1788
1789         sbi->max_cluster = total_clusters + FAT_START_ENT;
1790         /* check the free_clusters, it's not necessarily correct */
1791         if (sbi->free_clusters != -1 && sbi->free_clusters > total_clusters)
1792                 sbi->free_clusters = -1;
1793         /* check the prev_free, it's not necessarily correct */
1794         sbi->prev_free %= sbi->max_cluster;
1795         if (sbi->prev_free < FAT_START_ENT)
1796                 sbi->prev_free = FAT_START_ENT;
1797
1798         /* set up enough so that it can read an inode */
1799         fat_hash_init(sb);
1800         dir_hash_init(sb);
1801         fat_ent_access_init(sb);
1802
1803         /*
1804          * The low byte of FAT's first entry must have same value with
1805          * media-field.  But in real world, too many devices is
1806          * writing wrong value.  So, removed that validity check.
1807          *
1808          * if (FAT_FIRST_ENT(sb, media) != first)
1809          */
1810
1811         error = -EINVAL;
1812         sprintf(buf, "cp%d", sbi->options.codepage);
1813         sbi->nls_disk = load_nls(buf);
1814         if (!sbi->nls_disk) {
1815                 fat_msg(sb, KERN_ERR, "codepage %s not found", buf);
1816                 goto out_fail;
1817         }
1818
1819         /* FIXME: utf8 is using iocharset for upper/lower conversion */
1820         if (sbi->options.isvfat) {
1821                 sbi->nls_io = load_nls(sbi->options.iocharset);
1822                 if (!sbi->nls_io) {
1823                         fat_msg(sb, KERN_ERR, "IO charset %s not found",
1824                                sbi->options.iocharset);
1825                         goto out_fail;
1826                 }
1827         }
1828
1829         error = -ENOMEM;
1830         fat_inode = new_inode(sb);
1831         if (!fat_inode)
1832                 goto out_fail;
1833         sbi->fat_inode = fat_inode;
1834
1835         fsinfo_inode = new_inode(sb);
1836         if (!fsinfo_inode)
1837                 goto out_fail;
1838         fsinfo_inode->i_ino = MSDOS_FSINFO_INO;
1839         sbi->fsinfo_inode = fsinfo_inode;
1840         insert_inode_hash(fsinfo_inode);
1841
1842         root_inode = new_inode(sb);
1843         if (!root_inode)
1844                 goto out_fail;
1845         root_inode->i_ino = MSDOS_ROOT_INO;
1846         inode_set_iversion(root_inode, 1);
1847         error = fat_read_root(root_inode);
1848         if (error < 0) {
1849                 iput(root_inode);
1850                 goto out_fail;
1851         }
1852         error = -ENOMEM;
1853         insert_inode_hash(root_inode);
1854         fat_attach(root_inode, 0);
1855         sb->s_root = d_make_root(root_inode);
1856         if (!sb->s_root) {
1857                 fat_msg(sb, KERN_ERR, "get root inode failed");
1858                 goto out_fail;
1859         }
1860
1861         if (sbi->options.discard) {
1862                 struct request_queue *q = bdev_get_queue(sb->s_bdev);
1863                 if (!blk_queue_discard(q))
1864                         fat_msg(sb, KERN_WARNING,
1865                                         "mounting with \"discard\" option, but "
1866                                         "the device does not support discard");
1867         }
1868
1869         fat_set_state(sb, 1, 0);
1870         return 0;
1871
1872 out_invalid:
1873         error = -EINVAL;
1874         if (!silent)
1875                 fat_msg(sb, KERN_INFO, "Can't find a valid FAT filesystem");
1876
1877 out_fail:
1878         if (fsinfo_inode)
1879                 iput(fsinfo_inode);
1880         if (fat_inode)
1881                 iput(fat_inode);
1882         unload_nls(sbi->nls_io);
1883         unload_nls(sbi->nls_disk);
1884         fat_reset_iocharset(&sbi->options);
1885         sb->s_fs_info = NULL;
1886         kfree(sbi);
1887         return error;
1888 }
1889
1890 EXPORT_SYMBOL_GPL(fat_fill_super);
1891
1892 /*
1893  * helper function for fat_flush_inodes.  This writes both the inode
1894  * and the file data blocks, waiting for in flight data blocks before
1895  * the start of the call.  It does not wait for any io started
1896  * during the call
1897  */
1898 static int writeback_inode(struct inode *inode)
1899 {
1900
1901         int ret;
1902
1903         /* if we used wait=1, sync_inode_metadata waits for the io for the
1904         * inode to finish.  So wait=0 is sent down to sync_inode_metadata
1905         * and filemap_fdatawrite is used for the data blocks
1906         */
1907         ret = sync_inode_metadata(inode, 0);
1908         if (!ret)
1909                 ret = filemap_fdatawrite(inode->i_mapping);
1910         return ret;
1911 }
1912
1913 /*
1914  * write data and metadata corresponding to i1 and i2.  The io is
1915  * started but we do not wait for any of it to finish.
1916  *
1917  * filemap_flush is used for the block device, so if there is a dirty
1918  * page for a block already in flight, we will not wait and start the
1919  * io over again
1920  */
1921 int fat_flush_inodes(struct super_block *sb, struct inode *i1, struct inode *i2)
1922 {
1923         int ret = 0;
1924         if (!MSDOS_SB(sb)->options.flush)
1925                 return 0;
1926         if (i1)
1927                 ret = writeback_inode(i1);
1928         if (!ret && i2)
1929                 ret = writeback_inode(i2);
1930         if (!ret) {
1931                 struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping;
1932                 ret = filemap_flush(mapping);
1933         }
1934         return ret;
1935 }
1936 EXPORT_SYMBOL_GPL(fat_flush_inodes);
1937
1938 static int __init init_fat_fs(void)
1939 {
1940         int err;
1941
1942         err = fat_cache_init();
1943         if (err)
1944                 return err;
1945
1946         err = fat_init_inodecache();
1947         if (err)
1948                 goto failed;
1949
1950         return 0;
1951
1952 failed:
1953         fat_cache_destroy();
1954         return err;
1955 }
1956
1957 static void __exit exit_fat_fs(void)
1958 {
1959         fat_cache_destroy();
1960         fat_destroy_inodecache();
1961 }
1962
1963 module_init(init_fat_fs)
1964 module_exit(exit_fat_fs)
1965
1966 MODULE_LICENSE("GPL");