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 timespec ts;
 512         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 513         int error;
 514
 515         MSDOS_I(inode)->i_pos = 0;
 516         inode->i_uid = sbi->options.fs_uid;
 517         inode->i_gid = sbi->options.fs_gid;
 518         inode_inc_iversion(inode);
 519         inode->i_generation = get_seconds();
 520
 521         if ((de->attr & ATTR_DIR) && !IS_FREE(de->name)) {
 522                 inode->i_generation &= ~1;
 523                 inode->i_mode = fat_make_mode(sbi, de->attr, S_IRWXUGO);
 524                 inode->i_op = sbi->dir_ops;
 525                 inode->i_fop = &fat_dir_operations;
 526
 527                 MSDOS_I(inode)->i_start = fat_get_start(sbi, de);
 528                 MSDOS_I(inode)->i_logstart = MSDOS_I(inode)->i_start;
 529                 error = fat_calc_dir_size(inode);
 530                 if (error < 0)
 531                         return error;
 532                 MSDOS_I(inode)->mmu_private = inode->i_size;
 533
 534                 set_nlink(inode, fat_subdirs(inode));
 535
 536                 error = fat_validate_dir(inode);
 537                 if (error < 0)
 538                         return error;
 539         } else { /* not a directory */
 540                 inode->i_generation |= 1;
 541                 inode->i_mode = fat_make_mode(sbi, de->attr,
 542                         ((sbi->options.showexec && !is_exec(de->name + 8))
 543                          ? S_IRUGO|S_IWUGO : S_IRWXUGO));
 544                 MSDOS_I(inode)->i_start = fat_get_start(sbi, de);
 545
 546                 MSDOS_I(inode)->i_logstart = MSDOS_I(inode)->i_start;
 547                 inode->i_size = le32_to_cpu(de->size);
 548                 inode->i_op = &fat_file_inode_operations;
 549                 inode->i_fop = &fat_file_operations;
 550                 inode->i_mapping->a_ops = &fat_aops;
 551                 MSDOS_I(inode)->mmu_private = inode->i_size;
 552         }
 553         if (de->attr & ATTR_SYS) {
 554                 if (sbi->options.sys_immutable)
 555                         inode->i_flags |= S_IMMUTABLE;
 556         }
 557         fat_save_attrs(inode, de->attr);
 558
 559         inode->i_blocks = ((inode->i_size + (sbi->cluster_size - 1))
 560                            & ~((loff_t)sbi->cluster_size - 1)) >> 9;
 561
 562         fat_time_fat2unix(sbi, &ts, de->time, de->date, 0);
 563         inode->i_mtime = timespec_to_timespec64(ts);
 564         if (sbi->options.isvfat) {
 565                 fat_time_fat2unix(sbi, &ts, de->ctime,
 566                                   de->cdate, de->ctime_cs);
 567                 inode->i_ctime = timespec_to_timespec64(ts);
 568                 fat_time_fat2unix(sbi, &ts, 0, de->adate, 0);
 569                 inode->i_atime = timespec_to_timespec64(ts);
 570         } else
 571                 inode->i_ctime = inode->i_atime = inode->i_mtime;
 572
 573         return 0;
 574 }
 575
 576 static inline void fat_lock_build_inode(struct msdos_sb_info *sbi)
 577 {
 578         if (sbi->options.nfs == FAT_NFS_NOSTALE_RO)
 579                 mutex_lock(&sbi->nfs_build_inode_lock);
 580 }
 581
 582 static inline void fat_unlock_build_inode(struct msdos_sb_info *sbi)
 583 {
 584         if (sbi->options.nfs == FAT_NFS_NOSTALE_RO)
 585                 mutex_unlock(&sbi->nfs_build_inode_lock);
 586 }
 587
 588 struct inode *fat_build_inode(struct super_block *sb,
 589                         struct msdos_dir_entry *de, loff_t i_pos)
 590 {
 591         struct inode *inode;
 592         int err;
 593
 594         fat_lock_build_inode(MSDOS_SB(sb));
 595         inode = fat_iget(sb, i_pos);
 596         if (inode)
 597                 goto out;
 598         inode = new_inode(sb);
 599         if (!inode) {
 600                 inode = ERR_PTR(-ENOMEM);
 601                 goto out;
 602         }
 603         inode->i_ino = iunique(sb, MSDOS_ROOT_INO);
 604         inode_set_iversion(inode, 1);
 605         err = fat_fill_inode(inode, de);
 606         if (err) {
 607                 iput(inode);
 608                 inode = ERR_PTR(err);
 609                 goto out;
 610         }
 611         fat_attach(inode, i_pos);
 612         insert_inode_hash(inode);
 613 out:
 614         fat_unlock_build_inode(MSDOS_SB(sb));
 615         return inode;
 616 }
 617
 618 EXPORT_SYMBOL_GPL(fat_build_inode);
 619
 620 static int __fat_write_inode(struct inode *inode, int wait);
 621
 622 static void fat_free_eofblocks(struct inode *inode)
 623 {
 624         /* Release unwritten fallocated blocks on inode eviction. */
 625         if ((inode->i_blocks << 9) >
 626                         round_up(MSDOS_I(inode)->mmu_private,
 627                                 MSDOS_SB(inode->i_sb)->cluster_size)) {
 628                 int err;
 629
 630                 fat_truncate_blocks(inode, MSDOS_I(inode)->mmu_private);
 631                 /* Fallocate results in updating the i_start/iogstart
 632                  * for the zero byte file. So, make it return to
 633                  * original state during evict and commit it to avoid
 634                  * any corruption on the next access to the cluster
 635                  * chain for the file.
 636                  */
 637                 err = __fat_write_inode(inode, inode_needs_sync(inode));
 638                 if (err) {
 639                         fat_msg(inode->i_sb, KERN_WARNING, "Failed to "
 640                                         "update on disk inode for unused "
 641                                         "fallocated blocks, inode could be "
 642                                         "corrupted. Please run fsck");
 643                 }
 644
 645         }
 646 }
 647
 648 static void fat_evict_inode(struct inode *inode)
 649 {
 650         truncate_inode_pages_final(&inode->i_data);
 651         if (!inode->i_nlink) {
 652                 inode->i_size = 0;
 653                 fat_truncate_blocks(inode, 0);
 654         } else
 655                 fat_free_eofblocks(inode);
 656
 657         invalidate_inode_buffers(inode);
 658         clear_inode(inode);
 659         fat_cache_inval_inode(inode);
 660         fat_detach(inode);
 661 }
 662
 663 static void fat_set_state(struct super_block *sb,
 664                         unsigned int set, unsigned int force)
 665 {
 666         struct buffer_head *bh;
 667         struct fat_boot_sector *b;
 668         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 669
 670         /* do not change any thing if mounted read only */
 671         if (sb_rdonly(sb) && !force)
 672                 return;
 673
 674         /* do not change state if fs was dirty */
 675         if (sbi->dirty) {
 676                 /* warn only on set (mount). */
 677                 if (set)
 678                         fat_msg(sb, KERN_WARNING, "Volume was not properly "
 679                                 "unmounted. Some data may be corrupt. "
 680                                 "Please run fsck.");
 681                 return;
 682         }
 683
 684         bh = sb_bread(sb, 0);
 685         if (bh == NULL) {
 686                 fat_msg(sb, KERN_ERR, "unable to read boot sector "
 687                         "to mark fs as dirty");
 688                 return;
 689         }
 690
 691         b = (struct fat_boot_sector *) bh->b_data;
 692
 693         if (sbi->fat_bits == 32) {
 694                 if (set)
 695                         b->fat32.state |= FAT_STATE_DIRTY;
 696                 else
 697                         b->fat32.state &= ~FAT_STATE_DIRTY;
 698         } else /* fat 16 and 12 */ {
 699                 if (set)
 700                         b->fat16.state |= FAT_STATE_DIRTY;
 701                 else
 702                         b->fat16.state &= ~FAT_STATE_DIRTY;
 703         }
 704
 705         mark_buffer_dirty(bh);
 706         sync_dirty_buffer(bh);
 707         brelse(bh);
 708 }
 709
 710 static void delayed_free(struct rcu_head *p)
 711 {
 712         struct msdos_sb_info *sbi = container_of(p, struct msdos_sb_info, rcu);
 713         unload_nls(sbi->nls_disk);
 714         unload_nls(sbi->nls_io);
 715         if (sbi->options.iocharset != fat_default_iocharset)
 716                 kfree(sbi->options.iocharset);
 717         kfree(sbi);
 718 }
 719
 720 static void fat_put_super(struct super_block *sb)
 721 {
 722         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 723
 724         fat_set_state(sb, 0, 0);
 725
 726         iput(sbi->fsinfo_inode);
 727         iput(sbi->fat_inode);
 728
 729         call_rcu(&sbi->rcu, delayed_free);
 730 }
 731
 732 static struct kmem_cache *fat_inode_cachep;
 733
 734 static struct inode *fat_alloc_inode(struct super_block *sb)
 735 {
 736         struct msdos_inode_info *ei;
 737         ei = kmem_cache_alloc(fat_inode_cachep, GFP_NOFS);
 738         if (!ei)
 739                 return NULL;
 740
 741         init_rwsem(&ei->truncate_lock);
 742         return &ei->vfs_inode;
 743 }
 744
 745 static void fat_i_callback(struct rcu_head *head)
 746 {
 747         struct inode *inode = container_of(head, struct inode, i_rcu);
 748         kmem_cache_free(fat_inode_cachep, MSDOS_I(inode));
 749 }
 750
 751 static void fat_destroy_inode(struct inode *inode)
 752 {
 753         call_rcu(&inode->i_rcu, fat_i_callback);
 754 }
 755
 756 static void init_once(void *foo)
 757 {
 758         struct msdos_inode_info *ei = (struct msdos_inode_info *)foo;
 759
 760         spin_lock_init(&ei->cache_lru_lock);
 761         ei->nr_caches = 0;
 762         ei->cache_valid_id = FAT_CACHE_VALID + 1;
 763         INIT_LIST_HEAD(&ei->cache_lru);
 764         INIT_HLIST_NODE(&ei->i_fat_hash);
 765         INIT_HLIST_NODE(&ei->i_dir_hash);
 766         inode_init_once(&ei->vfs_inode);
 767 }
 768
 769 static int __init fat_init_inodecache(void)
 770 {
 771         fat_inode_cachep = kmem_cache_create("fat_inode_cache",
 772                                              sizeof(struct msdos_inode_info),
 773                                              0, (SLAB_RECLAIM_ACCOUNT|
 774                                                 SLAB_MEM_SPREAD|SLAB_ACCOUNT),
 775                                              init_once);
 776         if (fat_inode_cachep == NULL)
 777                 return -ENOMEM;
 778         return 0;
 779 }
 780
 781 static void __exit fat_destroy_inodecache(void)
 782 {
 783         /*
 784          * Make sure all delayed rcu free inodes are flushed before we
 785          * destroy cache.
 786          */
 787         rcu_barrier();
 788         kmem_cache_destroy(fat_inode_cachep);
 789 }
 790
 791 static int fat_remount(struct super_block *sb, int *flags, char *data)
 792 {
 793         bool new_rdonly;
 794         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 795         *flags |= SB_NODIRATIME | (sbi->options.isvfat ? 0 : SB_NOATIME);
 796
 797         sync_filesystem(sb);
 798
 799         /* make sure we update state on remount. */
 800         new_rdonly = *flags & SB_RDONLY;
 801         if (new_rdonly != sb_rdonly(sb)) {
 802                 if (new_rdonly)
 803                         fat_set_state(sb, 0, 0);
 804                 else
 805                         fat_set_state(sb, 1, 1);
 806         }
 807         return 0;
 808 }
 809
 810 static int fat_statfs(struct dentry *dentry, struct kstatfs *buf)
 811 {
 812         struct super_block *sb = dentry->d_sb;
 813         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 814         u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
 815
 816         /* If the count of free cluster is still unknown, counts it here. */
 817         if (sbi->free_clusters == -1 || !sbi->free_clus_valid) {
 818                 int err = fat_count_free_clusters(dentry->d_sb);
 819                 if (err)
 820                         return err;
 821         }
 822
 823         buf->f_type = dentry->d_sb->s_magic;
 824         buf->f_bsize = sbi->cluster_size;
 825         buf->f_blocks = sbi->max_cluster - FAT_START_ENT;
 826         buf->f_bfree = sbi->free_clusters;
 827         buf->f_bavail = sbi->free_clusters;
 828         buf->f_fsid.val[0] = (u32)id;
 829         buf->f_fsid.val[1] = (u32)(id >> 32);
 830         buf->f_namelen =
 831                 (sbi->options.isvfat ? FAT_LFN_LEN : 12) * NLS_MAX_CHARSET_SIZE;
 832
 833         return 0;
 834 }
 835
 836 static int __fat_write_inode(struct inode *inode, int wait)
 837 {
 838         struct timespec ts;
 839         struct super_block *sb = inode->i_sb;
 840         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 841         struct buffer_head *bh;
 842         struct msdos_dir_entry *raw_entry;
 843         loff_t i_pos;
 844         sector_t blocknr;
 845         int err, offset;
 846
 847         if (inode->i_ino == MSDOS_ROOT_INO)
 848                 return 0;
 849
 850 retry:
 851         i_pos = fat_i_pos_read(sbi, inode);
 852         if (!i_pos)
 853                 return 0;
 854
 855         fat_get_blknr_offset(sbi, i_pos, &blocknr, &offset);
 856         bh = sb_bread(sb, blocknr);
 857         if (!bh) {
 858                 fat_msg(sb, KERN_ERR, "unable to read inode block "
 859                        "for updating (i_pos %lld)", i_pos);
 860                 return -EIO;
 861         }
 862         spin_lock(&sbi->inode_hash_lock);
 863         if (i_pos != MSDOS_I(inode)->i_pos) {
 864                 spin_unlock(&sbi->inode_hash_lock);
 865                 brelse(bh);
 866                 goto retry;
 867         }
 868
 869         raw_entry = &((struct msdos_dir_entry *) (bh->b_data))[offset];
 870         if (S_ISDIR(inode->i_mode))
 871                 raw_entry->size = 0;
 872         else
 873                 raw_entry->size = cpu_to_le32(inode->i_size);
 874         raw_entry->attr = fat_make_attrs(inode);
 875         fat_set_start(raw_entry, MSDOS_I(inode)->i_logstart);
 876         ts = timespec64_to_timespec(inode->i_mtime);
 877         fat_time_unix2fat(sbi, &ts, &raw_entry->time,
 878                           &raw_entry->date, NULL);
 879         if (sbi->options.isvfat) {
 880                 __le16 atime;
 881                 ts = timespec64_to_timespec(inode->i_ctime);
 882                 fat_time_unix2fat(sbi, &ts, &raw_entry->ctime,
 883                                   &raw_entry->cdate, &raw_entry->ctime_cs);
 884                 ts = timespec64_to_timespec(inode->i_atime);
 885                 fat_time_unix2fat(sbi, &ts, &atime,
 886                                   &raw_entry->adate, NULL);
 887         }
 888         spin_unlock(&sbi->inode_hash_lock);
 889         mark_buffer_dirty(bh);
 890         err = 0;
 891         if (wait)
 892                 err = sync_dirty_buffer(bh);
 893         brelse(bh);
 894         return err;
 895 }
 896
 897 static int fat_write_inode(struct inode *inode, struct writeback_control *wbc)
 898 {
 899         int err;
 900
 901         if (inode->i_ino == MSDOS_FSINFO_INO) {
 902                 struct super_block *sb = inode->i_sb;
 903
 904                 mutex_lock(&MSDOS_SB(sb)->s_lock);
 905                 err = fat_clusters_flush(sb);
 906                 mutex_unlock(&MSDOS_SB(sb)->s_lock);
 907         } else
 908                 err = __fat_write_inode(inode, wbc->sync_mode == WB_SYNC_ALL);
 909
 910         return err;
 911 }
 912
 913 int fat_sync_inode(struct inode *inode)
 914 {
 915         return __fat_write_inode(inode, 1);
 916 }
 917
 918 EXPORT_SYMBOL_GPL(fat_sync_inode);
 919
 920 static int fat_show_options(struct seq_file *m, struct dentry *root);
 921 static const struct super_operations fat_sops = {
 922         .alloc_inode    = fat_alloc_inode,
 923         .destroy_inode  = fat_destroy_inode,
 924         .write_inode    = fat_write_inode,
 925         .evict_inode    = fat_evict_inode,
 926         .put_super      = fat_put_super,
 927         .statfs         = fat_statfs,
 928         .remount_fs     = fat_remount,
 929
 930         .show_options   = fat_show_options,
 931 };
 932
 933 static int fat_show_options(struct seq_file *m, struct dentry *root)
 934 {
 935         struct msdos_sb_info *sbi = MSDOS_SB(root->d_sb);
 936         struct fat_mount_options *opts = &sbi->options;
 937         int isvfat = opts->isvfat;
 938
 939         if (!uid_eq(opts->fs_uid, GLOBAL_ROOT_UID))
 940                 seq_printf(m, ",uid=%u",
 941                                 from_kuid_munged(&init_user_ns, opts->fs_uid));
 942         if (!gid_eq(opts->fs_gid, GLOBAL_ROOT_GID))
 943                 seq_printf(m, ",gid=%u",
 944                                 from_kgid_munged(&init_user_ns, opts->fs_gid));
 945         seq_printf(m, ",fmask=%04o", opts->fs_fmask);
 946         seq_printf(m, ",dmask=%04o", opts->fs_dmask);
 947         if (opts->allow_utime)
 948                 seq_printf(m, ",allow_utime=%04o", opts->allow_utime);
 949         if (sbi->nls_disk)
 950                 /* strip "cp" prefix from displayed option */
 951                 seq_printf(m, ",codepage=%s", &sbi->nls_disk->charset[2]);
 952         if (isvfat) {
 953                 if (sbi->nls_io)
 954                         seq_printf(m, ",iocharset=%s", sbi->nls_io->charset);
 955
 956                 switch (opts->shortname) {
 957                 case VFAT_SFN_DISPLAY_WIN95 | VFAT_SFN_CREATE_WIN95:
 958                         seq_puts(m, ",shortname=win95");
 959                         break;
 960                 case VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WINNT:
 961                         seq_puts(m, ",shortname=winnt");
 962                         break;
 963                 case VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WIN95:
 964                         seq_puts(m, ",shortname=mixed");
 965                         break;
 966                 case VFAT_SFN_DISPLAY_LOWER | VFAT_SFN_CREATE_WIN95:
 967                         seq_puts(m, ",shortname=lower");
 968                         break;
 969                 default:
 970                         seq_puts(m, ",shortname=unknown");
 971                         break;
 972                 }
 973         }
 974         if (opts->name_check != 'n')
 975                 seq_printf(m, ",check=%c", opts->name_check);
 976         if (opts->usefree)
 977                 seq_puts(m, ",usefree");
 978         if (opts->quiet)
 979                 seq_puts(m, ",quiet");
 980         if (opts->showexec)
 981                 seq_puts(m, ",showexec");
 982         if (opts->sys_immutable)
 983                 seq_puts(m, ",sys_immutable");
 984         if (!isvfat) {
 985                 if (opts->dotsOK)
 986                         seq_puts(m, ",dotsOK=yes");
 987                 if (opts->nocase)
 988                         seq_puts(m, ",nocase");
 989         } else {
 990                 if (opts->utf8)
 991                         seq_puts(m, ",utf8");
 992                 if (opts->unicode_xlate)
 993                         seq_puts(m, ",uni_xlate");
 994                 if (!opts->numtail)
 995                         seq_puts(m, ",nonumtail");
 996                 if (opts->rodir)
 997                         seq_puts(m, ",rodir");
 998         }
 999         if (opts->flush)
1000                 seq_puts(m, ",flush");
1001         if (opts->tz_set) {
1002                 if (opts->time_offset)
1003                         seq_printf(m, ",time_offset=%d", opts->time_offset);
1004                 else
1005                         seq_puts(m, ",tz=UTC");
1006         }
1007         if (opts->errors == FAT_ERRORS_CONT)
1008                 seq_puts(m, ",errors=continue");
1009         else if (opts->errors == FAT_ERRORS_PANIC)
1010                 seq_puts(m, ",errors=panic");
1011         else
1012                 seq_puts(m, ",errors=remount-ro");
1013         if (opts->nfs == FAT_NFS_NOSTALE_RO)
1014                 seq_puts(m, ",nfs=nostale_ro");
1015         else if (opts->nfs)
1016                 seq_puts(m, ",nfs=stale_rw");
1017         if (opts->discard)
1018                 seq_puts(m, ",discard");
1019         if (opts->dos1xfloppy)
1020                 seq_puts(m, ",dos1xfloppy");
1021
1022         return 0;
1023 }
1024
1025 enum {
1026         Opt_check_n, Opt_check_r, Opt_check_s, Opt_uid, Opt_gid,
1027         Opt_umask, Opt_dmask, Opt_fmask, Opt_allow_utime, Opt_codepage,
1028         Opt_usefree, Opt_nocase, Opt_quiet, Opt_showexec, Opt_debug,
1029         Opt_immutable, Opt_dots, Opt_nodots,
1030         Opt_charset, Opt_shortname_lower, Opt_shortname_win95,
1031         Opt_shortname_winnt, Opt_shortname_mixed, Opt_utf8_no, Opt_utf8_yes,
1032         Opt_uni_xl_no, Opt_uni_xl_yes, Opt_nonumtail_no, Opt_nonumtail_yes,
1033         Opt_obsolete, Opt_flush, Opt_tz_utc, Opt_rodir, Opt_err_cont,
1034         Opt_err_panic, Opt_err_ro, Opt_discard, Opt_nfs, Opt_time_offset,
1035         Opt_nfs_stale_rw, Opt_nfs_nostale_ro, Opt_err, Opt_dos1xfloppy,
1036 };
1037
1038 static const match_table_t fat_tokens = {
1039         {Opt_check_r, "check=relaxed"},
1040         {Opt_check_s, "check=strict"},
1041         {Opt_check_n, "check=normal"},
1042         {Opt_check_r, "check=r"},
1043         {Opt_check_s, "check=s"},
1044         {Opt_check_n, "check=n"},
1045         {Opt_uid, "uid=%u"},
1046         {Opt_gid, "gid=%u"},
1047         {Opt_umask, "umask=%o"},
1048         {Opt_dmask, "dmask=%o"},
1049         {Opt_fmask, "fmask=%o"},
1050         {Opt_allow_utime, "allow_utime=%o"},
1051         {Opt_codepage, "codepage=%u"},
1052         {Opt_usefree, "usefree"},
1053         {Opt_nocase, "nocase"},
1054         {Opt_quiet, "quiet"},
1055         {Opt_showexec, "showexec"},
1056         {Opt_debug, "debug"},
1057         {Opt_immutable, "sys_immutable"},
1058         {Opt_flush, "flush"},
1059         {Opt_tz_utc, "tz=UTC"},
1060         {Opt_time_offset, "time_offset=%d"},
1061         {Opt_err_cont, "errors=continue"},
1062         {Opt_err_panic, "errors=panic"},
1063         {Opt_err_ro, "errors=remount-ro"},
1064         {Opt_discard, "discard"},
1065         {Opt_nfs_stale_rw, "nfs"},
1066         {Opt_nfs_stale_rw, "nfs=stale_rw"},
1067         {Opt_nfs_nostale_ro, "nfs=nostale_ro"},
1068         {Opt_dos1xfloppy, "dos1xfloppy"},
1069         {Opt_obsolete, "conv=binary"},
1070         {Opt_obsolete, "conv=text"},
1071         {Opt_obsolete, "conv=auto"},
1072         {Opt_obsolete, "conv=b"},
1073         {Opt_obsolete, "conv=t"},
1074         {Opt_obsolete, "conv=a"},
1075         {Opt_obsolete, "fat=%u"},
1076         {Opt_obsolete, "blocksize=%u"},
1077         {Opt_obsolete, "cvf_format=%20s"},
1078         {Opt_obsolete, "cvf_options=%100s"},
1079         {Opt_obsolete, "posix"},
1080         {Opt_err, NULL},
1081 };
1082 static const match_table_t msdos_tokens = {
1083         {Opt_nodots, "nodots"},
1084         {Opt_nodots, "dotsOK=no"},
1085         {Opt_dots, "dots"},
1086         {Opt_dots, "dotsOK=yes"},
1087         {Opt_err, NULL}
1088 };
1089 static const match_table_t vfat_tokens = {
1090         {Opt_charset, "iocharset=%s"},
1091         {Opt_shortname_lower, "shortname=lower"},
1092         {Opt_shortname_win95, "shortname=win95"},
1093         {Opt_shortname_winnt, "shortname=winnt"},
1094         {Opt_shortname_mixed, "shortname=mixed"},
1095         {Opt_utf8_no, "utf8=0"},                /* 0 or no or false */
1096         {Opt_utf8_no, "utf8=no"},
1097         {Opt_utf8_no, "utf8=false"},
1098         {Opt_utf8_yes, "utf8=1"},               /* empty or 1 or yes or true */
1099         {Opt_utf8_yes, "utf8=yes"},
1100         {Opt_utf8_yes, "utf8=true"},
1101         {Opt_utf8_yes, "utf8"},
1102         {Opt_uni_xl_no, "uni_xlate=0"},         /* 0 or no or false */
1103         {Opt_uni_xl_no, "uni_xlate=no"},
1104         {Opt_uni_xl_no, "uni_xlate=false"},
1105         {Opt_uni_xl_yes, "uni_xlate=1"},        /* empty or 1 or yes or true */
1106         {Opt_uni_xl_yes, "uni_xlate=yes"},
1107         {Opt_uni_xl_yes, "uni_xlate=true"},
1108         {Opt_uni_xl_yes, "uni_xlate"},
1109         {Opt_nonumtail_no, "nonumtail=0"},      /* 0 or no or false */
1110         {Opt_nonumtail_no, "nonumtail=no"},
1111         {Opt_nonumtail_no, "nonumtail=false"},
1112         {Opt_nonumtail_yes, "nonumtail=1"},     /* empty or 1 or yes or true */
1113         {Opt_nonumtail_yes, "nonumtail=yes"},
1114         {Opt_nonumtail_yes, "nonumtail=true"},
1115         {Opt_nonumtail_yes, "nonumtail"},
1116         {Opt_rodir, "rodir"},
1117         {Opt_err, NULL}
1118 };
1119
1120 static int parse_options(struct super_block *sb, char *options, int is_vfat,
1121                          int silent, int *debug, struct fat_mount_options *opts)
1122 {
1123         char *p;
1124         substring_t args[MAX_OPT_ARGS];
1125         int option;
1126         char *iocharset;
1127
1128         opts->isvfat = is_vfat;
1129
1130         opts->fs_uid = current_uid();
1131         opts->fs_gid = current_gid();
1132         opts->fs_fmask = opts->fs_dmask = current_umask();
1133         opts->allow_utime = -1;
1134         opts->codepage = fat_default_codepage;
1135         opts->iocharset = fat_default_iocharset;
1136         if (is_vfat) {
1137                 opts->shortname = VFAT_SFN_DISPLAY_WINNT|VFAT_SFN_CREATE_WIN95;
1138                 opts->rodir = 0;
1139         } else {
1140                 opts->shortname = 0;
1141                 opts->rodir = 1;
1142         }
1143         opts->name_check = 'n';
1144         opts->quiet = opts->showexec = opts->sys_immutable = opts->dotsOK =  0;
1145         opts->unicode_xlate = 0;
1146         opts->numtail = 1;
1147         opts->usefree = opts->nocase = 0;
1148         opts->tz_set = 0;
1149         opts->nfs = 0;
1150         opts->errors = FAT_ERRORS_RO;
1151         *debug = 0;
1152
1153         opts->utf8 = IS_ENABLED(CONFIG_FAT_DEFAULT_UTF8) && is_vfat;
1154
1155         if (!options)
1156                 goto out;
1157
1158         while ((p = strsep(&options, ",")) != NULL) {
1159                 int token;
1160                 if (!*p)
1161                         continue;
1162
1163                 token = match_token(p, fat_tokens, args);
1164                 if (token == Opt_err) {
1165                         if (is_vfat)
1166                                 token = match_token(p, vfat_tokens, args);
1167                         else
1168                                 token = match_token(p, msdos_tokens, args);
1169                 }
1170                 switch (token) {
1171                 case Opt_check_s:
1172                         opts->name_check = 's';
1173                         break;
1174                 case Opt_check_r:
1175                         opts->name_check = 'r';
1176                         break;
1177                 case Opt_check_n:
1178                         opts->name_check = 'n';
1179                         break;
1180                 case Opt_usefree:
1181                         opts->usefree = 1;
1182                         break;
1183                 case Opt_nocase:
1184                         if (!is_vfat)
1185                                 opts->nocase = 1;
1186                         else {
1187                                 /* for backward compatibility */
1188                                 opts->shortname = VFAT_SFN_DISPLAY_WIN95
1189                                         | VFAT_SFN_CREATE_WIN95;
1190                         }
1191                         break;
1192                 case Opt_quiet:
1193                         opts->quiet = 1;
1194                         break;
1195                 case Opt_showexec:
1196                         opts->showexec = 1;
1197                         break;
1198                 case Opt_debug:
1199                         *debug = 1;
1200                         break;
1201                 case Opt_immutable:
1202                         opts->sys_immutable = 1;
1203                         break;
1204                 case Opt_uid:
1205                         if (match_int(&args[0], &option))
1206                                 return -EINVAL;
1207                         opts->fs_uid = make_kuid(current_user_ns(), option);
1208                         if (!uid_valid(opts->fs_uid))
1209                                 return -EINVAL;
1210                         break;
1211                 case Opt_gid:
1212                         if (match_int(&args[0], &option))
1213                                 return -EINVAL;
1214                         opts->fs_gid = make_kgid(current_user_ns(), option);
1215                         if (!gid_valid(opts->fs_gid))
1216                                 return -EINVAL;
1217                         break;
1218                 case Opt_umask:
1219                         if (match_octal(&args[0], &option))
1220                                 return -EINVAL;
1221                         opts->fs_fmask = opts->fs_dmask = option;
1222                         break;
1223                 case Opt_dmask:
1224                         if (match_octal(&args[0], &option))
1225                                 return -EINVAL;
1226                         opts->fs_dmask = option;
1227                         break;
1228                 case Opt_fmask:
1229                         if (match_octal(&args[0], &option))
1230                                 return -EINVAL;
1231                         opts->fs_fmask = option;
1232                         break;
1233                 case Opt_allow_utime:
1234                         if (match_octal(&args[0], &option))
1235                                 return -EINVAL;
1236                         opts->allow_utime = option & (S_IWGRP | S_IWOTH);
1237                         break;
1238                 case Opt_codepage:
1239                         if (match_int(&args[0], &option))
1240                                 return -EINVAL;
1241                         opts->codepage = option;
1242                         break;
1243                 case Opt_flush:
1244                         opts->flush = 1;
1245                         break;
1246                 case Opt_time_offset:
1247                         if (match_int(&args[0], &option))
1248                                 return -EINVAL;
1249                         /*
1250                          * GMT+-12 zones may have DST corrections so at least
1251                          * 13 hours difference is needed. Make the limit 24
1252                          * just in case someone invents something unusual.
1253                          */
1254                         if (option < -24 * 60 || option > 24 * 60)
1255                                 return -EINVAL;
1256                         opts->tz_set = 1;
1257                         opts->time_offset = option;
1258                         break;
1259                 case Opt_tz_utc:
1260                         opts->tz_set = 1;
1261                         opts->time_offset = 0;
1262                         break;
1263                 case Opt_err_cont:
1264                         opts->errors = FAT_ERRORS_CONT;
1265                         break;
1266                 case Opt_err_panic:
1267                         opts->errors = FAT_ERRORS_PANIC;
1268                         break;
1269                 case Opt_err_ro:
1270                         opts->errors = FAT_ERRORS_RO;
1271                         break;
1272                 case Opt_nfs_stale_rw:
1273                         opts->nfs = FAT_NFS_STALE_RW;
1274                         break;
1275                 case Opt_nfs_nostale_ro:
1276                         opts->nfs = FAT_NFS_NOSTALE_RO;
1277                         break;
1278                 case Opt_dos1xfloppy:
1279                         opts->dos1xfloppy = 1;
1280                         break;
1281
1282                 /* msdos specific */
1283                 case Opt_dots:
1284                         opts->dotsOK = 1;
1285                         break;
1286                 case Opt_nodots:
1287                         opts->dotsOK = 0;
1288                         break;
1289
1290                 /* vfat specific */
1291                 case Opt_charset:
1292                         if (opts->iocharset != fat_default_iocharset)
1293                                 kfree(opts->iocharset);
1294                         iocharset = match_strdup(&args[0]);
1295                         if (!iocharset)
1296                                 return -ENOMEM;
1297                         opts->iocharset = iocharset;
1298                         break;
1299                 case Opt_shortname_lower:
1300                         opts->shortname = VFAT_SFN_DISPLAY_LOWER
1301                                         | VFAT_SFN_CREATE_WIN95;
1302                         break;
1303                 case Opt_shortname_win95:
1304                         opts->shortname = VFAT_SFN_DISPLAY_WIN95
1305                                         | VFAT_SFN_CREATE_WIN95;
1306                         break;
1307                 case Opt_shortname_winnt:
1308                         opts->shortname = VFAT_SFN_DISPLAY_WINNT
1309                                         | VFAT_SFN_CREATE_WINNT;
1310                         break;
1311                 case Opt_shortname_mixed:
1312                         opts->shortname = VFAT_SFN_DISPLAY_WINNT
1313                                         | VFAT_SFN_CREATE_WIN95;
1314                         break;
1315                 case Opt_utf8_no:               /* 0 or no or false */
1316                         opts->utf8 = 0;
1317                         break;
1318                 case Opt_utf8_yes:              /* empty or 1 or yes or true */
1319                         opts->utf8 = 1;
1320                         break;
1321                 case Opt_uni_xl_no:             /* 0 or no or false */
1322                         opts->unicode_xlate = 0;
1323                         break;
1324                 case Opt_uni_xl_yes:            /* empty or 1 or yes or true */
1325                         opts->unicode_xlate = 1;
1326                         break;
1327                 case Opt_nonumtail_no:          /* 0 or no or false */
1328                         opts->numtail = 1;      /* negated option */
1329                         break;
1330                 case Opt_nonumtail_yes:         /* empty or 1 or yes or true */
1331                         opts->numtail = 0;      /* negated option */
1332                         break;
1333                 case Opt_rodir:
1334                         opts->rodir = 1;
1335                         break;
1336                 case Opt_discard:
1337                         opts->discard = 1;
1338                         break;
1339
1340                 /* obsolete mount options */
1341                 case Opt_obsolete:
1342                         fat_msg(sb, KERN_INFO, "\"%s\" option is obsolete, "
1343                                "not supported now", p);
1344                         break;
1345                 /* unknown option */
1346                 default:
1347                         if (!silent) {
1348                                 fat_msg(sb, KERN_ERR,
1349                                        "Unrecognized mount option \"%s\" "
1350                                        "or missing value", p);
1351                         }
1352                         return -EINVAL;
1353                 }
1354         }
1355
1356 out:
1357         /* UTF-8 doesn't provide FAT semantics */
1358         if (!strcmp(opts->iocharset, "utf8")) {
1359                 fat_msg(sb, KERN_WARNING, "utf8 is not a recommended IO charset"
1360                        " for FAT filesystems, filesystem will be "
1361                        "case sensitive!");
1362         }
1363
1364         /* If user doesn't specify allow_utime, it's initialized from dmask. */
1365         if (opts->allow_utime == (unsigned short)-1)
1366                 opts->allow_utime = ~opts->fs_dmask & (S_IWGRP | S_IWOTH);
1367         if (opts->unicode_xlate)
1368                 opts->utf8 = 0;
1369         if (opts->nfs == FAT_NFS_NOSTALE_RO) {
1370                 sb->s_flags |= SB_RDONLY;
1371                 sb->s_export_op = &fat_export_ops_nostale;
1372         }
1373
1374         return 0;
1375 }
1376
1377 static void fat_dummy_inode_init(struct inode *inode)
1378 {
1379         /* Initialize this dummy inode to work as no-op. */
1380         MSDOS_I(inode)->mmu_private = 0;
1381         MSDOS_I(inode)->i_start = 0;
1382         MSDOS_I(inode)->i_logstart = 0;
1383         MSDOS_I(inode)->i_attrs = 0;
1384         MSDOS_I(inode)->i_pos = 0;
1385 }
1386
1387 static int fat_read_root(struct inode *inode)
1388 {
1389         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
1390         int error;
1391
1392         MSDOS_I(inode)->i_pos = MSDOS_ROOT_INO;
1393         inode->i_uid = sbi->options.fs_uid;
1394         inode->i_gid = sbi->options.fs_gid;
1395         inode_inc_iversion(inode);
1396         inode->i_generation = 0;
1397         inode->i_mode = fat_make_mode(sbi, ATTR_DIR, S_IRWXUGO);
1398         inode->i_op = sbi->dir_ops;
1399         inode->i_fop = &fat_dir_operations;
1400         if (sbi->fat_bits == 32) {
1401                 MSDOS_I(inode)->i_start = sbi->root_cluster;
1402                 error = fat_calc_dir_size(inode);
1403                 if (error < 0)
1404                         return error;
1405         } else {
1406                 MSDOS_I(inode)->i_start = 0;
1407                 inode->i_size = sbi->dir_entries * sizeof(struct msdos_dir_entry);
1408         }
1409         inode->i_blocks = ((inode->i_size + (sbi->cluster_size - 1))
1410                            & ~((loff_t)sbi->cluster_size - 1)) >> 9;
1411         MSDOS_I(inode)->i_logstart = 0;
1412         MSDOS_I(inode)->mmu_private = inode->i_size;
1413
1414         fat_save_attrs(inode, ATTR_DIR);
1415         inode->i_mtime.tv_sec = inode->i_atime.tv_sec = inode->i_ctime.tv_sec = 0;
1416         inode->i_mtime.tv_nsec = inode->i_atime.tv_nsec = inode->i_ctime.tv_nsec = 0;
1417         set_nlink(inode, fat_subdirs(inode)+2);
1418
1419         return 0;
1420 }
1421
1422 static unsigned long calc_fat_clusters(struct super_block *sb)
1423 {
1424         struct msdos_sb_info *sbi = MSDOS_SB(sb);
1425
1426         /* Divide first to avoid overflow */
1427         if (sbi->fat_bits != 12) {
1428                 unsigned long ent_per_sec = sb->s_blocksize * 8 / sbi->fat_bits;
1429                 return ent_per_sec * sbi->fat_length;
1430         }
1431
1432         return sbi->fat_length * sb->s_blocksize * 8 / sbi->fat_bits;
1433 }
1434
1435 static bool fat_bpb_is_zero(struct fat_boot_sector *b)
1436 {
1437         if (get_unaligned_le16(&b->sector_size))
1438                 return false;
1439         if (b->sec_per_clus)
1440                 return false;
1441         if (b->reserved)
1442                 return false;
1443         if (b->fats)
1444                 return false;
1445         if (get_unaligned_le16(&b->dir_entries))
1446                 return false;
1447         if (get_unaligned_le16(&b->sectors))
1448                 return false;
1449         if (b->media)
1450                 return false;
1451         if (b->fat_length)
1452                 return false;
1453         if (b->secs_track)
1454                 return false;
1455         if (b->heads)
1456                 return false;
1457         return true;
1458 }
1459
1460 static int fat_read_bpb(struct super_block *sb, struct fat_boot_sector *b,
1461         int silent, struct fat_bios_param_block *bpb)
1462 {
1463         int error = -EINVAL;
1464
1465         /* Read in BPB ... */
1466         memset(bpb, 0, sizeof(*bpb));
1467         bpb->fat_sector_size = get_unaligned_le16(&b->sector_size);
1468         bpb->fat_sec_per_clus = b->sec_per_clus;
1469         bpb->fat_reserved = le16_to_cpu(b->reserved);
1470         bpb->fat_fats = b->fats;
1471         bpb->fat_dir_entries = get_unaligned_le16(&b->dir_entries);
1472         bpb->fat_sectors = get_unaligned_le16(&b->sectors);
1473         bpb->fat_fat_length = le16_to_cpu(b->fat_length);
1474         bpb->fat_total_sect = le32_to_cpu(b->total_sect);
1475
1476         bpb->fat16_state = b->fat16.state;
1477         bpb->fat16_vol_id = get_unaligned_le32(b->fat16.vol_id);
1478
1479         bpb->fat32_length = le32_to_cpu(b->fat32.length);
1480         bpb->fat32_root_cluster = le32_to_cpu(b->fat32.root_cluster);
1481         bpb->fat32_info_sector = le16_to_cpu(b->fat32.info_sector);
1482         bpb->fat32_state = b->fat32.state;
1483         bpb->fat32_vol_id = get_unaligned_le32(b->fat32.vol_id);
1484
1485         /* Validate this looks like a FAT filesystem BPB */
1486         if (!bpb->fat_reserved) {
1487                 if (!silent)
1488                         fat_msg(sb, KERN_ERR,
1489                                 "bogus number of reserved sectors");
1490                 goto out;
1491         }
1492         if (!bpb->fat_fats) {
1493                 if (!silent)
1494                         fat_msg(sb, KERN_ERR, "bogus number of FAT structure");
1495                 goto out;
1496         }
1497
1498         /*
1499          * Earlier we checked here that b->secs_track and b->head are nonzero,
1500          * but it turns out valid FAT filesystems can have zero there.
1501          */
1502
1503         if (!fat_valid_media(b->media)) {
1504                 if (!silent)
1505                         fat_msg(sb, KERN_ERR, "invalid media value (0x%02x)",
1506                                 (unsigned)b->media);
1507                 goto out;
1508         }
1509
1510         if (!is_power_of_2(bpb->fat_sector_size)
1511             || (bpb->fat_sector_size < 512)
1512             || (bpb->fat_sector_size > 4096)) {
1513                 if (!silent)
1514                         fat_msg(sb, KERN_ERR, "bogus logical sector size %u",
1515                                (unsigned)bpb->fat_sector_size);
1516                 goto out;
1517         }
1518
1519         if (!is_power_of_2(bpb->fat_sec_per_clus)) {
1520                 if (!silent)
1521                         fat_msg(sb, KERN_ERR, "bogus sectors per cluster %u",
1522                                 (unsigned)bpb->fat_sec_per_clus);
1523                 goto out;
1524         }
1525
1526         error = 0;
1527
1528 out:
1529         return error;
1530 }
1531
1532 static int fat_read_static_bpb(struct super_block *sb,
1533         struct fat_boot_sector *b, int silent,
1534         struct fat_bios_param_block *bpb)
1535 {
1536         static const char *notdos1x = "This doesn't look like a DOS 1.x volume";
1537
1538         struct fat_floppy_defaults *fdefaults = NULL;
1539         int error = -EINVAL;
1540         sector_t bd_sects;
1541         unsigned i;
1542
1543         bd_sects = i_size_read(sb->s_bdev->bd_inode) / SECTOR_SIZE;
1544
1545         /* 16-bit DOS 1.x reliably wrote bootstrap short-jmp code */
1546         if (b->ignored[0] != 0xeb || b->ignored[2] != 0x90) {
1547                 if (!silent)
1548                         fat_msg(sb, KERN_ERR,
1549                                 "%s; no bootstrapping code", notdos1x);
1550                 goto out;
1551         }
1552
1553         /*
1554          * If any value in this region is non-zero, it isn't archaic
1555          * DOS.
1556          */
1557         if (!fat_bpb_is_zero(b)) {
1558                 if (!silent)
1559                         fat_msg(sb, KERN_ERR,
1560                                 "%s; DOS 2.x BPB is non-zero", notdos1x);
1561                 goto out;
1562         }
1563
1564         for (i = 0; i < ARRAY_SIZE(floppy_defaults); i++) {
1565                 if (floppy_defaults[i].nr_sectors == bd_sects) {
1566                         fdefaults = &floppy_defaults[i];
1567                         break;
1568                 }
1569         }
1570
1571         if (fdefaults == NULL) {
1572                 if (!silent)
1573                         fat_msg(sb, KERN_WARNING,
1574                                 "This looks like a DOS 1.x volume, but isn't a recognized floppy size (%llu sectors)",
1575                                 (u64)bd_sects);
1576                 goto out;
1577         }
1578
1579         if (!silent)
1580                 fat_msg(sb, KERN_INFO,
1581                         "This looks like a DOS 1.x volume; assuming default BPB values");
1582
1583         memset(bpb, 0, sizeof(*bpb));
1584         bpb->fat_sector_size = SECTOR_SIZE;
1585         bpb->fat_sec_per_clus = fdefaults->sec_per_clus;
1586         bpb->fat_reserved = 1;
1587         bpb->fat_fats = 2;
1588         bpb->fat_dir_entries = fdefaults->dir_entries;
1589         bpb->fat_sectors = fdefaults->nr_sectors;
1590         bpb->fat_fat_length = fdefaults->fat_length;
1591
1592         error = 0;
1593
1594 out:
1595         return error;
1596 }
1597
1598 /*
1599  * Read the super block of an MS-DOS FS.
1600  */
1601 int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat,
1602                    void (*setup)(struct super_block *))
1603 {
1604         struct inode *root_inode = NULL, *fat_inode = NULL;
1605         struct inode *fsinfo_inode = NULL;
1606         struct buffer_head *bh;
1607         struct fat_bios_param_block bpb;
1608         struct msdos_sb_info *sbi;
1609         u16 logical_sector_size;
1610         u32 total_sectors, total_clusters, fat_clusters, rootdir_sectors;
1611         int debug;
1612         long error;
1613         char buf[50];
1614
1615         /*
1616          * GFP_KERNEL is ok here, because while we do hold the
1617          * superblock lock, memory pressure can't call back into
1618          * the filesystem, since we're only just about to mount
1619          * it and have no inodes etc active!
1620          */
1621         sbi = kzalloc(sizeof(struct msdos_sb_info), GFP_KERNEL);
1622         if (!sbi)
1623                 return -ENOMEM;
1624         sb->s_fs_info = sbi;
1625
1626         sb->s_flags |= SB_NODIRATIME;
1627         sb->s_magic = MSDOS_SUPER_MAGIC;
1628         sb->s_op = &fat_sops;
1629         sb->s_export_op = &fat_export_ops;
1630         mutex_init(&sbi->nfs_build_inode_lock);
1631         ratelimit_state_init(&sbi->ratelimit, DEFAULT_RATELIMIT_INTERVAL,
1632                              DEFAULT_RATELIMIT_BURST);
1633
1634         error = parse_options(sb, data, isvfat, silent, &debug, &sbi->options);
1635         if (error)
1636                 goto out_fail;
1637
1638         setup(sb); /* flavour-specific stuff that needs options */
1639
1640         error = -EIO;
1641         sb_min_blocksize(sb, 512);
1642         bh = sb_bread(sb, 0);
1643         if (bh == NULL) {
1644                 fat_msg(sb, KERN_ERR, "unable to read boot sector");
1645                 goto out_fail;
1646         }
1647
1648         error = fat_read_bpb(sb, (struct fat_boot_sector *)bh->b_data, silent,
1649                 &bpb);
1650         if (error == -EINVAL && sbi->options.dos1xfloppy)
1651                 error = fat_read_static_bpb(sb,
1652                         (struct fat_boot_sector *)bh->b_data, silent, &bpb);
1653         brelse(bh);
1654
1655         if (error == -EINVAL)
1656                 goto out_invalid;
1657         else if (error)
1658                 goto out_fail;
1659
1660         logical_sector_size = bpb.fat_sector_size;
1661         sbi->sec_per_clus = bpb.fat_sec_per_clus;
1662
1663         error = -EIO;
1664         if (logical_sector_size < sb->s_blocksize) {
1665                 fat_msg(sb, KERN_ERR, "logical sector size too small for device"
1666                        " (logical sector size = %u)", logical_sector_size);
1667                 goto out_fail;
1668         }
1669
1670         if (logical_sector_size > sb->s_blocksize) {
1671                 struct buffer_head *bh_resize;
1672
1673                 if (!sb_set_blocksize(sb, logical_sector_size)) {
1674                         fat_msg(sb, KERN_ERR, "unable to set blocksize %u",
1675                                logical_sector_size);
1676                         goto out_fail;
1677                 }
1678
1679                 /* Verify that the larger boot sector is fully readable */
1680                 bh_resize = sb_bread(sb, 0);
1681                 if (bh_resize == NULL) {
1682                         fat_msg(sb, KERN_ERR, "unable to read boot sector"
1683                                " (logical sector size = %lu)",
1684                                sb->s_blocksize);
1685                         goto out_fail;
1686                 }
1687                 brelse(bh_resize);
1688         }
1689
1690         mutex_init(&sbi->s_lock);
1691         sbi->cluster_size = sb->s_blocksize * sbi->sec_per_clus;
1692         sbi->cluster_bits = ffs(sbi->cluster_size) - 1;
1693         sbi->fats = bpb.fat_fats;
1694         sbi->fat_bits = 0;              /* Don't know yet */
1695         sbi->fat_start = bpb.fat_reserved;
1696         sbi->fat_length = bpb.fat_fat_length;
1697         sbi->root_cluster = 0;
1698         sbi->free_clusters = -1;        /* Don't know yet */
1699         sbi->free_clus_valid = 0;
1700         sbi->prev_free = FAT_START_ENT;
1701         sb->s_maxbytes = 0xffffffff;
1702
1703         if (!sbi->fat_length && bpb.fat32_length) {
1704                 struct fat_boot_fsinfo *fsinfo;
1705                 struct buffer_head *fsinfo_bh;
1706
1707                 /* Must be FAT32 */
1708                 sbi->fat_bits = 32;
1709                 sbi->fat_length = bpb.fat32_length;
1710                 sbi->root_cluster = bpb.fat32_root_cluster;
1711
1712                 /* MC - if info_sector is 0, don't multiply by 0 */
1713                 sbi->fsinfo_sector = bpb.fat32_info_sector;
1714                 if (sbi->fsinfo_sector == 0)
1715                         sbi->fsinfo_sector = 1;
1716
1717                 fsinfo_bh = sb_bread(sb, sbi->fsinfo_sector);
1718                 if (fsinfo_bh == NULL) {
1719                         fat_msg(sb, KERN_ERR, "bread failed, FSINFO block"
1720                                " (sector = %lu)", sbi->fsinfo_sector);
1721                         goto out_fail;
1722                 }
1723
1724                 fsinfo = (struct fat_boot_fsinfo *)fsinfo_bh->b_data;
1725                 if (!IS_FSINFO(fsinfo)) {
1726                         fat_msg(sb, KERN_WARNING, "Invalid FSINFO signature: "
1727                                "0x%08x, 0x%08x (sector = %lu)",
1728                                le32_to_cpu(fsinfo->signature1),
1729                                le32_to_cpu(fsinfo->signature2),
1730                                sbi->fsinfo_sector);
1731                 } else {
1732                         if (sbi->options.usefree)
1733                                 sbi->free_clus_valid = 1;
1734                         sbi->free_clusters = le32_to_cpu(fsinfo->free_clusters);
1735                         sbi->prev_free = le32_to_cpu(fsinfo->next_cluster);
1736                 }
1737
1738                 brelse(fsinfo_bh);
1739         }
1740
1741         /* interpret volume ID as a little endian 32 bit integer */
1742         if (sbi->fat_bits == 32)
1743                 sbi->vol_id = bpb.fat32_vol_id;
1744         else /* fat 16 or 12 */
1745                 sbi->vol_id = bpb.fat16_vol_id;
1746
1747         sbi->dir_per_block = sb->s_blocksize / sizeof(struct msdos_dir_entry);
1748         sbi->dir_per_block_bits = ffs(sbi->dir_per_block) - 1;
1749
1750         sbi->dir_start = sbi->fat_start + sbi->fats * sbi->fat_length;
1751         sbi->dir_entries = bpb.fat_dir_entries;
1752         if (sbi->dir_entries & (sbi->dir_per_block - 1)) {
1753                 if (!silent)
1754                         fat_msg(sb, KERN_ERR, "bogus number of directory entries"
1755                                " (%u)", sbi->dir_entries);
1756                 goto out_invalid;
1757         }
1758
1759         rootdir_sectors = sbi->dir_entries
1760                 * sizeof(struct msdos_dir_entry) / sb->s_blocksize;
1761         sbi->data_start = sbi->dir_start + rootdir_sectors;
1762         total_sectors = bpb.fat_sectors;
1763         if (total_sectors == 0)
1764                 total_sectors = bpb.fat_total_sect;
1765
1766         total_clusters = (total_sectors - sbi->data_start) / sbi->sec_per_clus;
1767
1768         if (sbi->fat_bits != 32)
1769                 sbi->fat_bits = (total_clusters > MAX_FAT12) ? 16 : 12;
1770
1771         /* some OSes set FAT_STATE_DIRTY and clean it on unmount. */
1772         if (sbi->fat_bits == 32)
1773                 sbi->dirty = bpb.fat32_state & FAT_STATE_DIRTY;
1774         else /* fat 16 or 12 */
1775                 sbi->dirty = bpb.fat16_state & FAT_STATE_DIRTY;
1776
1777         /* check that FAT table does not overflow */
1778         fat_clusters = calc_fat_clusters(sb);
1779         total_clusters = min(total_clusters, fat_clusters - FAT_START_ENT);
1780         if (total_clusters > MAX_FAT(sb)) {
1781                 if (!silent)
1782                         fat_msg(sb, KERN_ERR, "count of clusters too big (%u)",
1783                                total_clusters);
1784                 goto out_invalid;
1785         }
1786
1787         sbi->max_cluster = total_clusters + FAT_START_ENT;
1788         /* check the free_clusters, it's not necessarily correct */
1789         if (sbi->free_clusters != -1 && sbi->free_clusters > total_clusters)
1790                 sbi->free_clusters = -1;
1791         /* check the prev_free, it's not necessarily correct */
1792         sbi->prev_free %= sbi->max_cluster;
1793         if (sbi->prev_free < FAT_START_ENT)
1794                 sbi->prev_free = FAT_START_ENT;
1795
1796         /* set up enough so that it can read an inode */
1797         fat_hash_init(sb);
1798         dir_hash_init(sb);
1799         fat_ent_access_init(sb);
1800
1801         /*
1802          * The low byte of FAT's first entry must have same value with
1803          * media-field.  But in real world, too many devices is
1804          * writing wrong value.  So, removed that validity check.
1805          *
1806          * if (FAT_FIRST_ENT(sb, media) != first)
1807          */
1808
1809         error = -EINVAL;
1810         sprintf(buf, "cp%d", sbi->options.codepage);
1811         sbi->nls_disk = load_nls(buf);
1812         if (!sbi->nls_disk) {
1813                 fat_msg(sb, KERN_ERR, "codepage %s not found", buf);
1814                 goto out_fail;
1815         }
1816
1817         /* FIXME: utf8 is using iocharset for upper/lower conversion */
1818         if (sbi->options.isvfat) {
1819                 sbi->nls_io = load_nls(sbi->options.iocharset);
1820                 if (!sbi->nls_io) {
1821                         fat_msg(sb, KERN_ERR, "IO charset %s not found",
1822                                sbi->options.iocharset);
1823                         goto out_fail;
1824                 }
1825         }
1826
1827         error = -ENOMEM;
1828         fat_inode = new_inode(sb);
1829         if (!fat_inode)
1830                 goto out_fail;
1831         fat_dummy_inode_init(fat_inode);
1832         sbi->fat_inode = fat_inode;
1833
1834         fsinfo_inode = new_inode(sb);
1835         if (!fsinfo_inode)
1836                 goto out_fail;
1837         fat_dummy_inode_init(fsinfo_inode);
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         if (sbi->options.iocharset != fat_default_iocharset)
1885                 kfree(sbi->options.iocharset);
1886         sb->s_fs_info = NULL;
1887         kfree(sbi);
1888         return error;
1889 }
1890
1891 EXPORT_SYMBOL_GPL(fat_fill_super);
1892
1893 /*
1894  * helper function for fat_flush_inodes.  This writes both the inode
1895  * and the file data blocks, waiting for in flight data blocks before
1896  * the start of the call.  It does not wait for any io started
1897  * during the call
1898  */
1899 static int writeback_inode(struct inode *inode)
1900 {
1901
1902         int ret;
1903
1904         /* if we used wait=1, sync_inode_metadata waits for the io for the
1905         * inode to finish.  So wait=0 is sent down to sync_inode_metadata
1906         * and filemap_fdatawrite is used for the data blocks
1907         */
1908         ret = sync_inode_metadata(inode, 0);
1909         if (!ret)
1910                 ret = filemap_fdatawrite(inode->i_mapping);
1911         return ret;
1912 }
1913
1914 /*
1915  * write data and metadata corresponding to i1 and i2.  The io is
1916  * started but we do not wait for any of it to finish.
1917  *
1918  * filemap_flush is used for the block device, so if there is a dirty
1919  * page for a block already in flight, we will not wait and start the
1920  * io over again
1921  */
1922 int fat_flush_inodes(struct super_block *sb, struct inode *i1, struct inode *i2)
1923 {
1924         int ret = 0;
1925         if (!MSDOS_SB(sb)->options.flush)
1926                 return 0;
1927         if (i1)
1928                 ret = writeback_inode(i1);
1929         if (!ret && i2)
1930                 ret = writeback_inode(i2);
1931         if (!ret) {
1932                 struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping;
1933                 ret = filemap_flush(mapping);
1934         }
1935         return ret;
1936 }
1937 EXPORT_SYMBOL_GPL(fat_flush_inodes);
1938
1939 static int __init init_fat_fs(void)
1940 {
1941         int err;
1942
1943         err = fat_cache_init();
1944         if (err)
1945                 return err;
1946
1947         err = fat_init_inodecache();
1948         if (err)
1949                 goto failed;
1950
1951         return 0;
1952
1953 failed:
1954         fat_cache_destroy();
1955         return err;
1956 }
1957
1958 static void __exit exit_fat_fs(void)
1959 {
1960         fat_cache_destroy();
1961         fat_destroy_inodecache();
1962 }
1963
1964 module_init(init_fat_fs)
1965 module_exit(exit_fat_fs)
1966
1967 MODULE_LICENSE("GPL");