fs/fat/inode.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  linux/fs/fat/inode.c
   4  *
   5  *  Written 1992,1993 by Werner Almesberger
   6  *  VFAT extensions by Gordon Chaffee, merged with msdos fs by Henrik Storner
   7  *  Rewritten for the constant inumbers support by Al Viro
   8  *
   9  *  Fixes:
  10  *
  11  *      Max Cohan: Fixed invalid FSINFO offset when info_sector is 0
  12  */
  13
  14 #include <linux/module.h>
  15 #include <linux/pagemap.h>
  16 #include <linux/mpage.h>
  17 #include <linux/vfs.h>
  18 #include <linux/seq_file.h>
  19 #include <linux/parser.h>
  20 #include <linux/uio.h>
  21 #include <linux/blkdev.h>
  22 #include <linux/backing-dev.h>
  23 #include <asm/unaligned.h>
  24 #include <linux/iversion.h>
  25 #include "fat.h"
  26
  27 #ifndef CONFIG_FAT_DEFAULT_IOCHARSET
  28 /* if user don't select VFAT, this is undefined. */
  29 #define CONFIG_FAT_DEFAULT_IOCHARSET    ""
  30 #endif
  31
  32 #define KB_IN_SECTORS 2
  33
  34 /*
  35  * A deserialized copy of the on-disk structure laid out in struct
  36  * fat_boot_sector.
  37  */
  38 struct fat_bios_param_block {
  39         u16     fat_sector_size;
  40         u8      fat_sec_per_clus;
  41         u16     fat_reserved;
  42         u8      fat_fats;
  43         u16     fat_dir_entries;
  44         u16     fat_sectors;
  45         u16     fat_fat_length;
  46         u32     fat_total_sect;
  47
  48         u8      fat16_state;
  49         u32     fat16_vol_id;
  50
  51         u32     fat32_length;
  52         u32     fat32_root_cluster;
  53         u16     fat32_info_sector;
  54         u8      fat32_state;
  55         u32     fat32_vol_id;
  56 };
  57
  58 static int fat_default_codepage = CONFIG_FAT_DEFAULT_CODEPAGE;
  59 static char fat_default_iocharset[] = CONFIG_FAT_DEFAULT_IOCHARSET;
  60
  61 static struct fat_floppy_defaults {
  62         unsigned nr_sectors;
  63         unsigned sec_per_clus;
  64         unsigned dir_entries;
  65         unsigned media;
  66         unsigned fat_length;
  67 } floppy_defaults[] = {
  68 {
  69         .nr_sectors = 160 * KB_IN_SECTORS,
  70         .sec_per_clus = 1,
  71         .dir_entries = 64,
  72         .media = 0xFE,
  73         .fat_length = 1,
  74 },
  75 {
  76         .nr_sectors = 180 * KB_IN_SECTORS,
  77         .sec_per_clus = 1,
  78         .dir_entries = 64,
  79         .media = 0xFC,
  80         .fat_length = 2,
  81 },
  82 {
  83         .nr_sectors = 320 * KB_IN_SECTORS,
  84         .sec_per_clus = 2,
  85         .dir_entries = 112,
  86         .media = 0xFF,
  87         .fat_length = 1,
  88 },
  89 {
  90         .nr_sectors = 360 * KB_IN_SECTORS,
  91         .sec_per_clus = 2,
  92         .dir_entries = 112,
  93         .media = 0xFD,
  94         .fat_length = 2,
  95 },
  96 };
  97
  98 int fat_add_cluster(struct inode *inode)
  99 {
 100         int err, cluster;
 101
 102         err = fat_alloc_clusters(inode, &cluster, 1);
 103         if (err)
 104                 return err;
 105         /* FIXME: this cluster should be added after data of this
 106          * cluster is writed */
 107         err = fat_chain_add(inode, cluster, 1);
 108         if (err)
 109                 fat_free_clusters(inode, cluster);
 110         return err;
 111 }
 112
 113 static inline int __fat_get_block(struct inode *inode, sector_t iblock,
 114                                   unsigned long *max_blocks,
 115                                   struct buffer_head *bh_result, int create)
 116 {
 117         struct super_block *sb = inode->i_sb;
 118         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 119         unsigned long mapped_blocks;
 120         sector_t phys, last_block;
 121         int err, offset;
 122
 123         err = fat_bmap(inode, iblock, &phys, &mapped_blocks, create, false);
 124         if (err)
 125                 return err;
 126         if (phys) {
 127                 map_bh(bh_result, sb, phys);
 128                 *max_blocks = min(mapped_blocks, *max_blocks);
 129                 return 0;
 130         }
 131         if (!create)
 132                 return 0;
 133
 134         if (iblock != MSDOS_I(inode)->mmu_private >> sb->s_blocksize_bits) {
 135                 fat_fs_error(sb, "corrupted file size (i_pos %lld, %lld)",
 136                         MSDOS_I(inode)->i_pos, MSDOS_I(inode)->mmu_private);
 137                 return -EIO;
 138         }
 139
 140         last_block = inode->i_blocks >> (sb->s_blocksize_bits - 9);
 141         offset = (unsigned long)iblock & (sbi->sec_per_clus - 1);
 142         /*
 143          * allocate a cluster according to the following.
 144          * 1) no more available blocks
 145          * 2) not part of fallocate region
 146          */
 147         if (!offset && !(iblock < last_block)) {
 148                 /* TODO: multiple cluster allocation would be desirable. */
 149                 err = fat_add_cluster(inode);
 150                 if (err)
 151                         return err;
 152         }
 153         /* available blocks on this cluster */
 154         mapped_blocks = sbi->sec_per_clus - offset;
 155
 156         *max_blocks = min(mapped_blocks, *max_blocks);
 157         MSDOS_I(inode)->mmu_private += *max_blocks << sb->s_blocksize_bits;
 158
 159         err = fat_bmap(inode, iblock, &phys, &mapped_blocks, create, false);
 160         if (err)
 161                 return err;
 162         if (!phys) {
 163                 fat_fs_error(sb,
 164                              "invalid FAT chain (i_pos %lld, last_block %llu)",
 165                              MSDOS_I(inode)->i_pos,
 166                              (unsigned long long)last_block);
 167                 return -EIO;
 168         }
 169
 170         BUG_ON(*max_blocks != mapped_blocks);
 171         set_buffer_new(bh_result);
 172         map_bh(bh_result, sb, phys);
 173
 174         return 0;
 175 }
 176
 177 static int fat_get_block(struct inode *inode, sector_t iblock,
 178                          struct buffer_head *bh_result, int create)
 179 {
 180         struct super_block *sb = inode->i_sb;
 181         unsigned long max_blocks = bh_result->b_size >> inode->i_blkbits;
 182         int err;
 183
 184         err = __fat_get_block(inode, iblock, &max_blocks, bh_result, create);
 185         if (err)
 186                 return err;
 187         bh_result->b_size = max_blocks << sb->s_blocksize_bits;
 188         return 0;
 189 }
 190
 191 static int fat_writepage(struct page *page, struct writeback_control *wbc)
 192 {
 193         return block_write_full_page(page, fat_get_block, wbc);
 194 }
 195
 196 static int fat_writepages(struct address_space *mapping,
 197                           struct writeback_control *wbc)
 198 {
 199         return mpage_writepages(mapping, wbc, fat_get_block);
 200 }
 201
 202 static int fat_readpage(struct file *file, struct page *page)
 203 {
 204         return mpage_readpage(page, fat_get_block);
 205 }
 206
 207 static int fat_readpages(struct file *file, struct address_space *mapping,
 208                          struct list_head *pages, unsigned nr_pages)
 209 {
 210         return mpage_readpages(mapping, pages, nr_pages, fat_get_block);
 211 }
 212
 213 static void fat_write_failed(struct address_space *mapping, loff_t to)
 214 {
 215         struct inode *inode = mapping->host;
 216
 217         if (to > inode->i_size) {
 218                 truncate_pagecache(inode, inode->i_size);
 219                 fat_truncate_blocks(inode, inode->i_size);
 220         }
 221 }
 222
 223 static int fat_write_begin(struct file *file, struct address_space *mapping,
 224                         loff_t pos, unsigned len, unsigned flags,
 225                         struct page **pagep, void **fsdata)
 226 {
 227         int err;
 228
 229         *pagep = NULL;
 230         err = cont_write_begin(file, mapping, pos, len, flags,
 231                                 pagep, fsdata, fat_get_block,
 232                                 &MSDOS_I(mapping->host)->mmu_private);
 233         if (err < 0)
 234                 fat_write_failed(mapping, pos + len);
 235         return err;
 236 }
 237
 238 static int fat_write_end(struct file *file, struct address_space *mapping,
 239                         loff_t pos, unsigned len, unsigned copied,
 240                         struct page *pagep, void *fsdata)
 241 {
 242         struct inode *inode = mapping->host;
 243         int err;
 244         err = generic_write_end(file, mapping, pos, len, copied, pagep, fsdata);
 245         if (err < len)
 246                 fat_write_failed(mapping, pos + len);
 247         if (!(err < 0) && !(MSDOS_I(inode)->i_attrs & ATTR_ARCH)) {
 248                 fat_truncate_time(inode, NULL, S_CTIME|S_MTIME);
 249                 MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
 250                 mark_inode_dirty(inode);
 251         }
 252         return err;
 253 }
 254
 255 static ssize_t fat_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
 256 {
 257         struct file *file = iocb->ki_filp;
 258         struct address_space *mapping = file->f_mapping;
 259         struct inode *inode = mapping->host;
 260         size_t count = iov_iter_count(iter);
 261         loff_t offset = iocb->ki_pos;
 262         ssize_t ret;
 263
 264         if (iov_iter_rw(iter) == WRITE) {
 265                 /*
 266                  * FIXME: blockdev_direct_IO() doesn't use ->write_begin(),
 267                  * so we need to update the ->mmu_private to block boundary.
 268                  *
 269                  * But we must fill the remaining area or hole by nul for
 270                  * updating ->mmu_private.
 271                  *
 272                  * Return 0, and fallback to normal buffered write.
 273                  */
 274                 loff_t size = offset + count;
 275                 if (MSDOS_I(inode)->mmu_private < size)
 276                         return 0;
 277         }
 278
 279         /*
 280          * FAT need to use the DIO_LOCKING for avoiding the race
 281          * condition of fat_get_block() and ->truncate().
 282          */
 283         ret = blockdev_direct_IO(iocb, inode, iter, fat_get_block);
 284         if (ret < 0 && iov_iter_rw(iter) == WRITE)
 285                 fat_write_failed(mapping, offset + count);
 286
 287         return ret;
 288 }
 289
 290 static int fat_get_block_bmap(struct inode *inode, sector_t iblock,
 291                 struct buffer_head *bh_result, int create)
 292 {
 293         struct super_block *sb = inode->i_sb;
 294         unsigned long max_blocks = bh_result->b_size >> inode->i_blkbits;
 295         int err;
 296         sector_t bmap;
 297         unsigned long mapped_blocks;
 298
 299         BUG_ON(create != 0);
 300
 301         err = fat_bmap(inode, iblock, &bmap, &mapped_blocks, create, true);
 302         if (err)
 303                 return err;
 304
 305         if (bmap) {
 306                 map_bh(bh_result, sb, bmap);
 307                 max_blocks = min(mapped_blocks, max_blocks);
 308         }
 309
 310         bh_result->b_size = max_blocks << sb->s_blocksize_bits;
 311
 312         return 0;
 313 }
 314
 315 static sector_t _fat_bmap(struct address_space *mapping, sector_t block)
 316 {
 317         sector_t blocknr;
 318
 319         /* fat_get_cluster() assumes the requested blocknr isn't truncated. */
 320         down_read(&MSDOS_I(mapping->host)->truncate_lock);
 321         blocknr = generic_block_bmap(mapping, block, fat_get_block_bmap);
 322         up_read(&MSDOS_I(mapping->host)->truncate_lock);
 323
 324         return blocknr;
 325 }
 326
 327 /*
 328  * fat_block_truncate_page() zeroes out a mapping from file offset `from'
 329  * up to the end of the block which corresponds to `from'.
 330  * This is required during truncate to physically zeroout the tail end
 331  * of that block so it doesn't yield old data if the file is later grown.
 332  * Also, avoid causing failure from fsx for cases of "data past EOF"
 333  */
 334 int fat_block_truncate_page(struct inode *inode, loff_t from)
 335 {
 336         return block_truncate_page(inode->i_mapping, from, fat_get_block);
 337 }
 338
 339 static const struct address_space_operations fat_aops = {
 340         .readpage       = fat_readpage,
 341         .readpages      = fat_readpages,
 342         .writepage      = fat_writepage,
 343         .writepages     = fat_writepages,
 344         .write_begin    = fat_write_begin,
 345         .write_end      = fat_write_end,
 346         .direct_IO      = fat_direct_IO,
 347         .bmap           = _fat_bmap
 348 };
 349
 350 /*
 351  * New FAT inode stuff. We do the following:
 352  *      a) i_ino is constant and has nothing with on-disk location.
 353  *      b) FAT manages its own cache of directory entries.
 354  *      c) *This* cache is indexed by on-disk location.
 355  *      d) inode has an associated directory entry, all right, but
 356  *              it may be unhashed.
 357  *      e) currently entries are stored within struct inode. That should
 358  *              change.
 359  *      f) we deal with races in the following way:
 360  *              1. readdir() and lookup() do FAT-dir-cache lookup.
 361  *              2. rename() unhashes the F-d-c entry and rehashes it in
 362  *                      a new place.
 363  *              3. unlink() and rmdir() unhash F-d-c entry.
 364  *              4. fat_write_inode() checks whether the thing is unhashed.
 365  *                      If it is we silently return. If it isn't we do bread(),
 366  *                      check if the location is still valid and retry if it
 367  *                      isn't. Otherwise we do changes.
 368  *              5. Spinlock is used to protect hash/unhash/location check/lookup
 369  *              6. fat_evict_inode() unhashes the F-d-c entry.
 370  *              7. lookup() and readdir() do igrab() if they find a F-d-c entry
 371  *                      and consider negative result as cache miss.
 372  */
 373
 374 static void fat_hash_init(struct super_block *sb)
 375 {
 376         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 377         int i;
 378
 379         spin_lock_init(&sbi->inode_hash_lock);
 380         for (i = 0; i < FAT_HASH_SIZE; i++)
 381                 INIT_HLIST_HEAD(&sbi->inode_hashtable[i]);
 382 }
 383
 384 static inline unsigned long fat_hash(loff_t i_pos)
 385 {
 386         return hash_32(i_pos, FAT_HASH_BITS);
 387 }
 388
 389 static void dir_hash_init(struct super_block *sb)
 390 {
 391         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 392         int i;
 393
 394         spin_lock_init(&sbi->dir_hash_lock);
 395         for (i = 0; i < FAT_HASH_SIZE; i++)
 396                 INIT_HLIST_HEAD(&sbi->dir_hashtable[i]);
 397 }
 398
 399 void fat_attach(struct inode *inode, loff_t i_pos)
 400 {
 401         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 402
 403         if (inode->i_ino != MSDOS_ROOT_INO) {
 404                 struct hlist_head *head =   sbi->inode_hashtable
 405                                           + fat_hash(i_pos);
 406
 407                 spin_lock(&sbi->inode_hash_lock);
 408                 MSDOS_I(inode)->i_pos = i_pos;
 409                 hlist_add_head(&MSDOS_I(inode)->i_fat_hash, head);
 410                 spin_unlock(&sbi->inode_hash_lock);
 411         }
 412
 413         /* If NFS support is enabled, cache the mapping of start cluster
 414          * to directory inode. This is used during reconnection of
 415          * dentries to the filesystem root.
 416          */
 417         if (S_ISDIR(inode->i_mode) && sbi->options.nfs) {
 418                 struct hlist_head *d_head = sbi->dir_hashtable;
 419                 d_head += fat_dir_hash(MSDOS_I(inode)->i_logstart);
 420
 421                 spin_lock(&sbi->dir_hash_lock);
 422                 hlist_add_head(&MSDOS_I(inode)->i_dir_hash, d_head);
 423                 spin_unlock(&sbi->dir_hash_lock);
 424         }
 425 }
 426 EXPORT_SYMBOL_GPL(fat_attach);
 427
 428 void fat_detach(struct inode *inode)
 429 {
 430         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 431         spin_lock(&sbi->inode_hash_lock);
 432         MSDOS_I(inode)->i_pos = 0;
 433         hlist_del_init(&MSDOS_I(inode)->i_fat_hash);
 434         spin_unlock(&sbi->inode_hash_lock);
 435
 436         if (S_ISDIR(inode->i_mode) && sbi->options.nfs) {
 437                 spin_lock(&sbi->dir_hash_lock);
 438                 hlist_del_init(&MSDOS_I(inode)->i_dir_hash);
 439                 spin_unlock(&sbi->dir_hash_lock);
 440         }
 441 }
 442 EXPORT_SYMBOL_GPL(fat_detach);
 443
 444 struct inode *fat_iget(struct super_block *sb, loff_t i_pos)
 445 {
 446         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 447         struct hlist_head *head = sbi->inode_hashtable + fat_hash(i_pos);
 448         struct msdos_inode_info *i;
 449         struct inode *inode = NULL;
 450
 451         spin_lock(&sbi->inode_hash_lock);
 452         hlist_for_each_entry(i, head, i_fat_hash) {
 453                 BUG_ON(i->vfs_inode.i_sb != sb);
 454                 if (i->i_pos != i_pos)
 455                         continue;
 456                 inode = igrab(&i->vfs_inode);
 457                 if (inode)
 458                         break;
 459         }
 460         spin_unlock(&sbi->inode_hash_lock);
 461         return inode;
 462 }
 463
 464 static int is_exec(unsigned char *extension)
 465 {
 466         unsigned char exe_extensions[] = "EXECOMBAT", *walk;
 467
 468         for (walk = exe_extensions; *walk; walk += 3)
 469                 if (!strncmp(extension, walk, 3))
 470                         return 1;
 471         return 0;
 472 }
 473
 474 static int fat_calc_dir_size(struct inode *inode)
 475 {
 476         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 477         int ret, fclus, dclus;
 478
 479         inode->i_size = 0;
 480         if (MSDOS_I(inode)->i_start == 0)
 481                 return 0;
 482
 483         ret = fat_get_cluster(inode, FAT_ENT_EOF, &fclus, &dclus);
 484         if (ret < 0)
 485                 return ret;
 486         inode->i_size = (fclus + 1) << sbi->cluster_bits;
 487
 488         return 0;
 489 }
 490
 491 static int fat_validate_dir(struct inode *dir)
 492 {
 493         struct super_block *sb = dir->i_sb;
 494
 495         if (dir->i_nlink < 2) {
 496                 /* Directory should have "."/".." entries at least. */
 497                 fat_fs_error(sb, "corrupted directory (invalid entries)");
 498                 return -EIO;
 499         }
 500         if (MSDOS_I(dir)->i_start == 0 ||
 501             MSDOS_I(dir)->i_start == MSDOS_SB(sb)->root_cluster) {
 502                 /* Directory should point valid cluster. */
 503                 fat_fs_error(sb, "corrupted directory (invalid i_start)");
 504                 return -EIO;
 505         }
 506         return 0;
 507 }
 508
 509 /* doesn't deal with root inode */
 510 int fat_fill_inode(struct inode *inode, struct msdos_dir_entry *de)
 511 {
 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, &inode->i_mtime, de->time, de->date, 0);
 563         if (sbi->options.isvfat) {
 564                 fat_time_fat2unix(sbi, &inode->i_ctime, de->ctime,
 565                                   de->cdate, de->ctime_cs);
 566                 fat_time_fat2unix(sbi, &inode->i_atime, 0, de->adate, 0);
 567         } else
 568                 fat_truncate_time(inode, &inode->i_mtime, S_ATIME|S_CTIME);
 569
 570         return 0;
 571 }
 572
 573 static inline void fat_lock_build_inode(struct msdos_sb_info *sbi)
 574 {
 575         if (sbi->options.nfs == FAT_NFS_NOSTALE_RO)
 576                 mutex_lock(&sbi->nfs_build_inode_lock);
 577 }
 578
 579 static inline void fat_unlock_build_inode(struct msdos_sb_info *sbi)
 580 {
 581         if (sbi->options.nfs == FAT_NFS_NOSTALE_RO)
 582                 mutex_unlock(&sbi->nfs_build_inode_lock);
 583 }
 584
 585 struct inode *fat_build_inode(struct super_block *sb,
 586                         struct msdos_dir_entry *de, loff_t i_pos)
 587 {
 588         struct inode *inode;
 589         int err;
 590
 591         fat_lock_build_inode(MSDOS_SB(sb));
 592         inode = fat_iget(sb, i_pos);
 593         if (inode)
 594                 goto out;
 595         inode = new_inode(sb);
 596         if (!inode) {
 597                 inode = ERR_PTR(-ENOMEM);
 598                 goto out;
 599         }
 600         inode->i_ino = iunique(sb, MSDOS_ROOT_INO);
 601         inode_set_iversion(inode, 1);
 602         err = fat_fill_inode(inode, de);
 603         if (err) {
 604                 iput(inode);
 605                 inode = ERR_PTR(err);
 606                 goto out;
 607         }
 608         fat_attach(inode, i_pos);
 609         insert_inode_hash(inode);
 610 out:
 611         fat_unlock_build_inode(MSDOS_SB(sb));
 612         return inode;
 613 }
 614
 615 EXPORT_SYMBOL_GPL(fat_build_inode);
 616
 617 static int __fat_write_inode(struct inode *inode, int wait);
 618
 619 static void fat_free_eofblocks(struct inode *inode)
 620 {
 621         /* Release unwritten fallocated blocks on inode eviction. */
 622         if ((inode->i_blocks << 9) >
 623                         round_up(MSDOS_I(inode)->mmu_private,
 624                                 MSDOS_SB(inode->i_sb)->cluster_size)) {
 625                 int err;
 626
 627                 fat_truncate_blocks(inode, MSDOS_I(inode)->mmu_private);
 628                 /* Fallocate results in updating the i_start/iogstart
 629                  * for the zero byte file. So, make it return to
 630                  * original state during evict and commit it to avoid
 631                  * any corruption on the next access to the cluster
 632                  * chain for the file.
 633                  */
 634                 err = __fat_write_inode(inode, inode_needs_sync(inode));
 635                 if (err) {
 636                         fat_msg(inode->i_sb, KERN_WARNING, "Failed to "
 637                                         "update on disk inode for unused "
 638                                         "fallocated blocks, inode could be "
 639                                         "corrupted. Please run fsck");
 640                 }
 641
 642         }
 643 }
 644
 645 static void fat_evict_inode(struct inode *inode)
 646 {
 647         truncate_inode_pages_final(&inode->i_data);
 648         if (!inode->i_nlink) {
 649                 inode->i_size = 0;
 650                 fat_truncate_blocks(inode, 0);
 651         } else
 652                 fat_free_eofblocks(inode);
 653
 654         invalidate_inode_buffers(inode);
 655         clear_inode(inode);
 656         fat_cache_inval_inode(inode);
 657         fat_detach(inode);
 658 }
 659
 660 static void fat_set_state(struct super_block *sb,
 661                         unsigned int set, unsigned int force)
 662 {
 663         struct buffer_head *bh;
 664         struct fat_boot_sector *b;
 665         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 666
 667         /* do not change any thing if mounted read only */
 668         if (sb_rdonly(sb) && !force)
 669                 return;
 670
 671         /* do not change state if fs was dirty */
 672         if (sbi->dirty) {
 673                 /* warn only on set (mount). */
 674                 if (set)
 675                         fat_msg(sb, KERN_WARNING, "Volume was not properly "
 676                                 "unmounted. Some data may be corrupt. "
 677                                 "Please run fsck.");
 678                 return;
 679         }
 680
 681         bh = sb_bread(sb, 0);
 682         if (bh == NULL) {
 683                 fat_msg(sb, KERN_ERR, "unable to read boot sector "
 684                         "to mark fs as dirty");
 685                 return;
 686         }
 687
 688         b = (struct fat_boot_sector *) bh->b_data;
 689
 690         if (is_fat32(sbi)) {
 691                 if (set)
 692                         b->fat32.state |= FAT_STATE_DIRTY;
 693                 else
 694                         b->fat32.state &= ~FAT_STATE_DIRTY;
 695         } else /* fat 16 and 12 */ {
 696                 if (set)
 697                         b->fat16.state |= FAT_STATE_DIRTY;
 698                 else
 699                         b->fat16.state &= ~FAT_STATE_DIRTY;
 700         }
 701
 702         mark_buffer_dirty(bh);
 703         sync_dirty_buffer(bh);
 704         brelse(bh);
 705 }
 706
 707 static void fat_reset_iocharset(struct fat_mount_options *opts)
 708 {
 709         if (opts->iocharset != fat_default_iocharset) {
 710                 /* Note: opts->iocharset can be NULL here */
 711                 kfree(opts->iocharset);
 712                 opts->iocharset = fat_default_iocharset;
 713         }
 714 }
 715
 716 static void delayed_free(struct rcu_head *p)
 717 {
 718         struct msdos_sb_info *sbi = container_of(p, struct msdos_sb_info, rcu);
 719         unload_nls(sbi->nls_disk);
 720         unload_nls(sbi->nls_io);
 721         fat_reset_iocharset(&sbi->options);
 722         kfree(sbi);
 723 }
 724
 725 static void fat_put_super(struct super_block *sb)
 726 {
 727         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 728
 729         fat_set_state(sb, 0, 0);
 730
 731         iput(sbi->fsinfo_inode);
 732         iput(sbi->fat_inode);
 733
 734         call_rcu(&sbi->rcu, delayed_free);
 735 }
 736
 737 static struct kmem_cache *fat_inode_cachep;
 738
 739 static struct inode *fat_alloc_inode(struct super_block *sb)
 740 {
 741         struct msdos_inode_info *ei;
 742         ei = kmem_cache_alloc(fat_inode_cachep, GFP_NOFS);
 743         if (!ei)
 744                 return NULL;
 745
 746         init_rwsem(&ei->truncate_lock);
 747         return &ei->vfs_inode;
 748 }
 749
 750 static void fat_free_inode(struct inode *inode)
 751 {
 752         kmem_cache_free(fat_inode_cachep, MSDOS_I(inode));
 753 }
 754
 755 static void init_once(void *foo)
 756 {
 757         struct msdos_inode_info *ei = (struct msdos_inode_info *)foo;
 758
 759         spin_lock_init(&ei->cache_lru_lock);
 760         ei->nr_caches = 0;
 761         ei->cache_valid_id = FAT_CACHE_VALID + 1;
 762         INIT_LIST_HEAD(&ei->cache_lru);
 763         INIT_HLIST_NODE(&ei->i_fat_hash);
 764         INIT_HLIST_NODE(&ei->i_dir_hash);
 765         inode_init_once(&ei->vfs_inode);
 766 }
 767
 768 static int __init fat_init_inodecache(void)
 769 {
 770         fat_inode_cachep = kmem_cache_create("fat_inode_cache",
 771                                              sizeof(struct msdos_inode_info),
 772                                              0, (SLAB_RECLAIM_ACCOUNT|
 773                                                 SLAB_MEM_SPREAD|SLAB_ACCOUNT),
 774                                              init_once);
 775         if (fat_inode_cachep == NULL)
 776                 return -ENOMEM;
 777         return 0;
 778 }
 779
 780 static void __exit fat_destroy_inodecache(void)
 781 {
 782         /*
 783          * Make sure all delayed rcu free inodes are flushed before we
 784          * destroy cache.
 785          */
 786         rcu_barrier();
 787         kmem_cache_destroy(fat_inode_cachep);
 788 }
 789
 790 static int fat_remount(struct super_block *sb, int *flags, char *data)
 791 {
 792         bool new_rdonly;
 793         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 794         *flags |= SB_NODIRATIME | (sbi->options.isvfat ? 0 : SB_NOATIME);
 795
 796         sync_filesystem(sb);
 797
 798         /* make sure we update state on remount. */
 799         new_rdonly = *flags & SB_RDONLY;
 800         if (new_rdonly != sb_rdonly(sb)) {
 801                 if (new_rdonly)
 802                         fat_set_state(sb, 0, 0);
 803                 else
 804                         fat_set_state(sb, 1, 1);
 805         }
 806         return 0;
 807 }
 808
 809 static int fat_statfs(struct dentry *dentry, struct kstatfs *buf)
 810 {
 811         struct super_block *sb = dentry->d_sb;
 812         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 813         u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
 814
 815         /* If the count of free cluster is still unknown, counts it here. */
 816         if (sbi->free_clusters == -1 || !sbi->free_clus_valid) {
 817                 int err = fat_count_free_clusters(dentry->d_sb);
 818                 if (err)
 819                         return err;
 820         }
 821
 822         buf->f_type = dentry->d_sb->s_magic;
 823         buf->f_bsize = sbi->cluster_size;
 824         buf->f_blocks = sbi->max_cluster - FAT_START_ENT;
 825         buf->f_bfree = sbi->free_clusters;
 826         buf->f_bavail = sbi->free_clusters;
 827         buf->f_fsid.val[0] = (u32)id;
 828         buf->f_fsid.val[1] = (u32)(id >> 32);
 829         buf->f_namelen =
 830                 (sbi->options.isvfat ? FAT_LFN_LEN : 12) * NLS_MAX_CHARSET_SIZE;
 831
 832         return 0;
 833 }
 834
 835 static int __fat_write_inode(struct inode *inode, int wait)
 836 {
 837         struct super_block *sb = inode->i_sb;
 838         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 839         struct buffer_head *bh;
 840         struct msdos_dir_entry *raw_entry;
 841         loff_t i_pos;
 842         sector_t blocknr;
 843         int err, offset;
 844
 845         if (inode->i_ino == MSDOS_ROOT_INO)
 846                 return 0;
 847
 848 retry:
 849         i_pos = fat_i_pos_read(sbi, inode);
 850         if (!i_pos)
 851                 return 0;
 852
 853         fat_get_blknr_offset(sbi, i_pos, &blocknr, &offset);
 854         bh = sb_bread(sb, blocknr);
 855         if (!bh) {
 856                 fat_msg(sb, KERN_ERR, "unable to read inode block "
 857                        "for updating (i_pos %lld)", i_pos);
 858                 return -EIO;
 859         }
 860         spin_lock(&sbi->inode_hash_lock);
 861         if (i_pos != MSDOS_I(inode)->i_pos) {
 862                 spin_unlock(&sbi->inode_hash_lock);
 863                 brelse(bh);
 864                 goto retry;
 865         }
 866
 867         raw_entry = &((struct msdos_dir_entry *) (bh->b_data))[offset];
 868         if (S_ISDIR(inode->i_mode))
 869                 raw_entry->size = 0;
 870         else
 871                 raw_entry->size = cpu_to_le32(inode->i_size);
 872         raw_entry->attr = fat_make_attrs(inode);
 873         fat_set_start(raw_entry, MSDOS_I(inode)->i_logstart);
 874         fat_time_unix2fat(sbi, &inode->i_mtime, &raw_entry->time,
 875                           &raw_entry->date, NULL);
 876         if (sbi->options.isvfat) {
 877                 __le16 atime;
 878                 fat_time_unix2fat(sbi, &inode->i_ctime, &raw_entry->ctime,
 879                                   &raw_entry->cdate, &raw_entry->ctime_cs);
 880                 fat_time_unix2fat(sbi, &inode->i_atime, &atime,
 881                                   &raw_entry->adate, NULL);
 882         }
 883         spin_unlock(&sbi->inode_hash_lock);
 884         mark_buffer_dirty(bh);
 885         err = 0;
 886         if (wait)
 887                 err = sync_dirty_buffer(bh);
 888         brelse(bh);
 889         return err;
 890 }
 891
 892 static int fat_write_inode(struct inode *inode, struct writeback_control *wbc)
 893 {
 894         int err;
 895
 896         if (inode->i_ino == MSDOS_FSINFO_INO) {
 897                 struct super_block *sb = inode->i_sb;
 898
 899                 mutex_lock(&MSDOS_SB(sb)->s_lock);
 900                 err = fat_clusters_flush(sb);
 901                 mutex_unlock(&MSDOS_SB(sb)->s_lock);
 902         } else
 903                 err = __fat_write_inode(inode, wbc->sync_mode == WB_SYNC_ALL);
 904
 905         return err;
 906 }
 907
 908 int fat_sync_inode(struct inode *inode)
 909 {
 910         return __fat_write_inode(inode, 1);
 911 }
 912
 913 EXPORT_SYMBOL_GPL(fat_sync_inode);
 914
 915 static int fat_show_options(struct seq_file *m, struct dentry *root);
 916 static const struct super_operations fat_sops = {
 917         .alloc_inode    = fat_alloc_inode,
 918         .free_inode     = fat_free_inode,
 919         .write_inode    = fat_write_inode,
 920         .evict_inode    = fat_evict_inode,
 921         .put_super      = fat_put_super,
 922         .statfs         = fat_statfs,
 923         .remount_fs     = fat_remount,
 924
 925         .show_options   = fat_show_options,
 926 };
 927
 928 static int fat_show_options(struct seq_file *m, struct dentry *root)
 929 {
 930         struct msdos_sb_info *sbi = MSDOS_SB(root->d_sb);
 931         struct fat_mount_options *opts = &sbi->options;
 932         int isvfat = opts->isvfat;
 933
 934         if (!uid_eq(opts->fs_uid, GLOBAL_ROOT_UID))
 935                 seq_printf(m, ",uid=%u",
 936                                 from_kuid_munged(&init_user_ns, opts->fs_uid));
 937         if (!gid_eq(opts->fs_gid, GLOBAL_ROOT_GID))
 938                 seq_printf(m, ",gid=%u",
 939                                 from_kgid_munged(&init_user_ns, opts->fs_gid));
 940         seq_printf(m, ",fmask=%04o", opts->fs_fmask);
 941         seq_printf(m, ",dmask=%04o", opts->fs_dmask);
 942         if (opts->allow_utime)
 943                 seq_printf(m, ",allow_utime=%04o", opts->allow_utime);
 944         if (sbi->nls_disk)
 945                 /* strip "cp" prefix from displayed option */
 946                 seq_printf(m, ",codepage=%s", &sbi->nls_disk->charset[2]);
 947         if (isvfat) {
 948                 if (sbi->nls_io)
 949                         seq_printf(m, ",iocharset=%s", sbi->nls_io->charset);
 950
 951                 switch (opts->shortname) {
 952                 case VFAT_SFN_DISPLAY_WIN95 | VFAT_SFN_CREATE_WIN95:
 953                         seq_puts(m, ",shortname=win95");
 954                         break;
 955                 case VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WINNT:
 956                         seq_puts(m, ",shortname=winnt");
 957                         break;
 958                 case VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WIN95:
 959                         seq_puts(m, ",shortname=mixed");
 960                         break;
 961                 case VFAT_SFN_DISPLAY_LOWER | VFAT_SFN_CREATE_WIN95:
 962                         seq_puts(m, ",shortname=lower");
 963                         break;
 964                 default:
 965                         seq_puts(m, ",shortname=unknown");
 966                         break;
 967                 }
 968         }
 969         if (opts->name_check != 'n')
 970                 seq_printf(m, ",check=%c", opts->name_check);
 971         if (opts->usefree)
 972                 seq_puts(m, ",usefree");
 973         if (opts->quiet)
 974                 seq_puts(m, ",quiet");
 975         if (opts->showexec)
 976                 seq_puts(m, ",showexec");
 977         if (opts->sys_immutable)
 978                 seq_puts(m, ",sys_immutable");
 979         if (!isvfat) {
 980                 if (opts->dotsOK)
 981                         seq_puts(m, ",dotsOK=yes");
 982                 if (opts->nocase)
 983                         seq_puts(m, ",nocase");
 984         } else {
 985                 if (opts->utf8)
 986                         seq_puts(m, ",utf8");
 987                 if (opts->unicode_xlate)
 988                         seq_puts(m, ",uni_xlate");
 989                 if (!opts->numtail)
 990                         seq_puts(m, ",nonumtail");
 991                 if (opts->rodir)
 992                         seq_puts(m, ",rodir");
 993         }
 994         if (opts->flush)
 995                 seq_puts(m, ",flush");
 996         if (opts->tz_set) {
 997                 if (opts->time_offset)
 998                         seq_printf(m, ",time_offset=%d", opts->time_offset);
 999                 else
1000                         seq_puts(m, ",tz=UTC");
1001         }
1002         if (opts->errors == FAT_ERRORS_CONT)
1003                 seq_puts(m, ",errors=continue");
1004         else if (opts->errors == FAT_ERRORS_PANIC)
1005                 seq_puts(m, ",errors=panic");
1006         else
1007                 seq_puts(m, ",errors=remount-ro");
1008         if (opts->nfs == FAT_NFS_NOSTALE_RO)
1009                 seq_puts(m, ",nfs=nostale_ro");
1010         else if (opts->nfs)
1011                 seq_puts(m, ",nfs=stale_rw");
1012         if (opts->discard)
1013                 seq_puts(m, ",discard");
1014         if (opts->dos1xfloppy)
1015                 seq_puts(m, ",dos1xfloppy");
1016
1017         return 0;
1018 }
1019
1020 enum {
1021         Opt_check_n, Opt_check_r, Opt_check_s, Opt_uid, Opt_gid,
1022         Opt_umask, Opt_dmask, Opt_fmask, Opt_allow_utime, Opt_codepage,
1023         Opt_usefree, Opt_nocase, Opt_quiet, Opt_showexec, Opt_debug,
1024         Opt_immutable, Opt_dots, Opt_nodots,
1025         Opt_charset, Opt_shortname_lower, Opt_shortname_win95,
1026         Opt_shortname_winnt, Opt_shortname_mixed, Opt_utf8_no, Opt_utf8_yes,
1027         Opt_uni_xl_no, Opt_uni_xl_yes, Opt_nonumtail_no, Opt_nonumtail_yes,
1028         Opt_obsolete, Opt_flush, Opt_tz_utc, Opt_rodir, Opt_err_cont,
1029         Opt_err_panic, Opt_err_ro, Opt_discard, Opt_nfs, Opt_time_offset,
1030         Opt_nfs_stale_rw, Opt_nfs_nostale_ro, Opt_err, Opt_dos1xfloppy,
1031 };
1032
1033 static const match_table_t fat_tokens = {
1034         {Opt_check_r, "check=relaxed"},
1035         {Opt_check_s, "check=strict"},
1036         {Opt_check_n, "check=normal"},
1037         {Opt_check_r, "check=r"},
1038         {Opt_check_s, "check=s"},
1039         {Opt_check_n, "check=n"},
1040         {Opt_uid, "uid=%u"},
1041         {Opt_gid, "gid=%u"},
1042         {Opt_umask, "umask=%o"},
1043         {Opt_dmask, "dmask=%o"},
1044         {Opt_fmask, "fmask=%o"},
1045         {Opt_allow_utime, "allow_utime=%o"},
1046         {Opt_codepage, "codepage=%u"},
1047         {Opt_usefree, "usefree"},
1048         {Opt_nocase, "nocase"},
1049         {Opt_quiet, "quiet"},
1050         {Opt_showexec, "showexec"},
1051         {Opt_debug, "debug"},
1052         {Opt_immutable, "sys_immutable"},
1053         {Opt_flush, "flush"},
1054         {Opt_tz_utc, "tz=UTC"},
1055         {Opt_time_offset, "time_offset=%d"},
1056         {Opt_err_cont, "errors=continue"},
1057         {Opt_err_panic, "errors=panic"},
1058         {Opt_err_ro, "errors=remount-ro"},
1059         {Opt_discard, "discard"},
1060         {Opt_nfs_stale_rw, "nfs"},
1061         {Opt_nfs_stale_rw, "nfs=stale_rw"},
1062         {Opt_nfs_nostale_ro, "nfs=nostale_ro"},
1063         {Opt_dos1xfloppy, "dos1xfloppy"},
1064         {Opt_obsolete, "conv=binary"},
1065         {Opt_obsolete, "conv=text"},
1066         {Opt_obsolete, "conv=auto"},
1067         {Opt_obsolete, "conv=b"},
1068         {Opt_obsolete, "conv=t"},
1069         {Opt_obsolete, "conv=a"},
1070         {Opt_obsolete, "fat=%u"},
1071         {Opt_obsolete, "blocksize=%u"},
1072         {Opt_obsolete, "cvf_format=%20s"},
1073         {Opt_obsolete, "cvf_options=%100s"},
1074         {Opt_obsolete, "posix"},
1075         {Opt_err, NULL},
1076 };
1077 static const match_table_t msdos_tokens = {
1078         {Opt_nodots, "nodots"},
1079         {Opt_nodots, "dotsOK=no"},
1080         {Opt_dots, "dots"},
1081         {Opt_dots, "dotsOK=yes"},
1082         {Opt_err, NULL}
1083 };
1084 static const match_table_t vfat_tokens = {
1085         {Opt_charset, "iocharset=%s"},
1086         {Opt_shortname_lower, "shortname=lower"},
1087         {Opt_shortname_win95, "shortname=win95"},
1088         {Opt_shortname_winnt, "shortname=winnt"},
1089         {Opt_shortname_mixed, "shortname=mixed"},
1090         {Opt_utf8_no, "utf8=0"},                /* 0 or no or false */
1091         {Opt_utf8_no, "utf8=no"},
1092         {Opt_utf8_no, "utf8=false"},
1093         {Opt_utf8_yes, "utf8=1"},               /* empty or 1 or yes or true */
1094         {Opt_utf8_yes, "utf8=yes"},
1095         {Opt_utf8_yes, "utf8=true"},
1096         {Opt_utf8_yes, "utf8"},
1097         {Opt_uni_xl_no, "uni_xlate=0"},         /* 0 or no or false */
1098         {Opt_uni_xl_no, "uni_xlate=no"},
1099         {Opt_uni_xl_no, "uni_xlate=false"},
1100         {Opt_uni_xl_yes, "uni_xlate=1"},        /* empty or 1 or yes or true */
1101         {Opt_uni_xl_yes, "uni_xlate=yes"},
1102         {Opt_uni_xl_yes, "uni_xlate=true"},
1103         {Opt_uni_xl_yes, "uni_xlate"},
1104         {Opt_nonumtail_no, "nonumtail=0"},      /* 0 or no or false */
1105         {Opt_nonumtail_no, "nonumtail=no"},
1106         {Opt_nonumtail_no, "nonumtail=false"},
1107         {Opt_nonumtail_yes, "nonumtail=1"},     /* empty or 1 or yes or true */
1108         {Opt_nonumtail_yes, "nonumtail=yes"},
1109         {Opt_nonumtail_yes, "nonumtail=true"},
1110         {Opt_nonumtail_yes, "nonumtail"},
1111         {Opt_rodir, "rodir"},
1112         {Opt_err, NULL}
1113 };
1114
1115 static int parse_options(struct super_block *sb, char *options, int is_vfat,
1116                          int silent, int *debug, struct fat_mount_options *opts)
1117 {
1118         char *p;
1119         substring_t args[MAX_OPT_ARGS];
1120         int option;
1121         char *iocharset;
1122
1123         opts->isvfat = is_vfat;
1124
1125         opts->fs_uid = current_uid();
1126         opts->fs_gid = current_gid();
1127         opts->fs_fmask = opts->fs_dmask = current_umask();
1128         opts->allow_utime = -1;
1129         opts->codepage = fat_default_codepage;
1130         fat_reset_iocharset(opts);
1131         if (is_vfat) {
1132                 opts->shortname = VFAT_SFN_DISPLAY_WINNT|VFAT_SFN_CREATE_WIN95;
1133                 opts->rodir = 0;
1134         } else {
1135                 opts->shortname = 0;
1136                 opts->rodir = 1;
1137         }
1138         opts->name_check = 'n';
1139         opts->quiet = opts->showexec = opts->sys_immutable = opts->dotsOK =  0;
1140         opts->unicode_xlate = 0;
1141         opts->numtail = 1;
1142         opts->usefree = opts->nocase = 0;
1143         opts->tz_set = 0;
1144         opts->nfs = 0;
1145         opts->errors = FAT_ERRORS_RO;
1146         *debug = 0;
1147
1148         opts->utf8 = IS_ENABLED(CONFIG_FAT_DEFAULT_UTF8) && is_vfat;
1149
1150         if (!options)
1151                 goto out;
1152
1153         while ((p = strsep(&options, ",")) != NULL) {
1154                 int token;
1155                 if (!*p)
1156                         continue;
1157
1158                 token = match_token(p, fat_tokens, args);
1159                 if (token == Opt_err) {
1160                         if (is_vfat)
1161                                 token = match_token(p, vfat_tokens, args);
1162                         else
1163                                 token = match_token(p, msdos_tokens, args);
1164                 }
1165                 switch (token) {
1166                 case Opt_check_s:
1167                         opts->name_check = 's';
1168                         break;
1169                 case Opt_check_r:
1170                         opts->name_check = 'r';
1171                         break;
1172                 case Opt_check_n:
1173                         opts->name_check = 'n';
1174                         break;
1175                 case Opt_usefree:
1176                         opts->usefree = 1;
1177                         break;
1178                 case Opt_nocase:
1179                         if (!is_vfat)
1180                                 opts->nocase = 1;
1181                         else {
1182                                 /* for backward compatibility */
1183                                 opts->shortname = VFAT_SFN_DISPLAY_WIN95
1184                                         | VFAT_SFN_CREATE_WIN95;
1185                         }
1186                         break;
1187                 case Opt_quiet:
1188                         opts->quiet = 1;
1189                         break;
1190                 case Opt_showexec:
1191                         opts->showexec = 1;
1192                         break;
1193                 case Opt_debug:
1194                         *debug = 1;
1195                         break;
1196                 case Opt_immutable:
1197                         opts->sys_immutable = 1;
1198                         break;
1199                 case Opt_uid:
1200                         if (match_int(&args[0], &option))
1201                                 return -EINVAL;
1202                         opts->fs_uid = make_kuid(current_user_ns(), option);
1203                         if (!uid_valid(opts->fs_uid))
1204                                 return -EINVAL;
1205                         break;
1206                 case Opt_gid:
1207                         if (match_int(&args[0], &option))
1208                                 return -EINVAL;
1209                         opts->fs_gid = make_kgid(current_user_ns(), option);
1210                         if (!gid_valid(opts->fs_gid))
1211                                 return -EINVAL;
1212                         break;
1213                 case Opt_umask:
1214                         if (match_octal(&args[0], &option))
1215                                 return -EINVAL;
1216                         opts->fs_fmask = opts->fs_dmask = option;
1217                         break;
1218                 case Opt_dmask:
1219                         if (match_octal(&args[0], &option))
1220                                 return -EINVAL;
1221                         opts->fs_dmask = option;
1222                         break;
1223                 case Opt_fmask:
1224                         if (match_octal(&args[0], &option))
1225                                 return -EINVAL;
1226                         opts->fs_fmask = option;
1227                         break;
1228                 case Opt_allow_utime:
1229                         if (match_octal(&args[0], &option))
1230                                 return -EINVAL;
1231                         opts->allow_utime = option & (S_IWGRP | S_IWOTH);
1232                         break;
1233                 case Opt_codepage:
1234                         if (match_int(&args[0], &option))
1235                                 return -EINVAL;
1236                         opts->codepage = option;
1237                         break;
1238                 case Opt_flush:
1239                         opts->flush = 1;
1240                         break;
1241                 case Opt_time_offset:
1242                         if (match_int(&args[0], &option))
1243                                 return -EINVAL;
1244                         /*
1245                          * GMT+-12 zones may have DST corrections so at least
1246                          * 13 hours difference is needed. Make the limit 24
1247                          * just in case someone invents something unusual.
1248                          */
1249                         if (option < -24 * 60 || option > 24 * 60)
1250                                 return -EINVAL;
1251                         opts->tz_set = 1;
1252                         opts->time_offset = option;
1253                         break;
1254                 case Opt_tz_utc:
1255                         opts->tz_set = 1;
1256                         opts->time_offset = 0;
1257                         break;
1258                 case Opt_err_cont:
1259                         opts->errors = FAT_ERRORS_CONT;
1260                         break;
1261                 case Opt_err_panic:
1262                         opts->errors = FAT_ERRORS_PANIC;
1263                         break;
1264                 case Opt_err_ro:
1265                         opts->errors = FAT_ERRORS_RO;
1266                         break;
1267                 case Opt_nfs_stale_rw:
1268                         opts->nfs = FAT_NFS_STALE_RW;
1269                         break;
1270                 case Opt_nfs_nostale_ro:
1271                         opts->nfs = FAT_NFS_NOSTALE_RO;
1272                         break;
1273                 case Opt_dos1xfloppy:
1274                         opts->dos1xfloppy = 1;
1275                         break;
1276
1277                 /* msdos specific */
1278                 case Opt_dots:
1279                         opts->dotsOK = 1;
1280                         break;
1281                 case Opt_nodots:
1282                         opts->dotsOK = 0;
1283                         break;
1284
1285                 /* vfat specific */
1286                 case Opt_charset:
1287                         fat_reset_iocharset(opts);
1288                         iocharset = match_strdup(&args[0]);
1289                         if (!iocharset)
1290                                 return -ENOMEM;
1291                         opts->iocharset = iocharset;
1292                         break;
1293                 case Opt_shortname_lower:
1294                         opts->shortname = VFAT_SFN_DISPLAY_LOWER
1295                                         | VFAT_SFN_CREATE_WIN95;
1296                         break;
1297                 case Opt_shortname_win95:
1298                         opts->shortname = VFAT_SFN_DISPLAY_WIN95
1299                                         | VFAT_SFN_CREATE_WIN95;
1300                         break;
1301                 case Opt_shortname_winnt:
1302                         opts->shortname = VFAT_SFN_DISPLAY_WINNT
1303                                         | VFAT_SFN_CREATE_WINNT;
1304                         break;
1305                 case Opt_shortname_mixed:
1306                         opts->shortname = VFAT_SFN_DISPLAY_WINNT
1307                                         | VFAT_SFN_CREATE_WIN95;
1308                         break;
1309                 case Opt_utf8_no:               /* 0 or no or false */
1310                         opts->utf8 = 0;
1311                         break;
1312                 case Opt_utf8_yes:              /* empty or 1 or yes or true */
1313                         opts->utf8 = 1;
1314                         break;
1315                 case Opt_uni_xl_no:             /* 0 or no or false */
1316                         opts->unicode_xlate = 0;
1317                         break;
1318                 case Opt_uni_xl_yes:            /* empty or 1 or yes or true */
1319                         opts->unicode_xlate = 1;
1320                         break;
1321                 case Opt_nonumtail_no:          /* 0 or no or false */
1322                         opts->numtail = 1;      /* negated option */
1323                         break;
1324                 case Opt_nonumtail_yes:         /* empty or 1 or yes or true */
1325                         opts->numtail = 0;      /* negated option */
1326                         break;
1327                 case Opt_rodir:
1328                         opts->rodir = 1;
1329                         break;
1330                 case Opt_discard:
1331                         opts->discard = 1;
1332                         break;
1333
1334                 /* obsolete mount options */
1335                 case Opt_obsolete:
1336                         fat_msg(sb, KERN_INFO, "\"%s\" option is obsolete, "
1337                                "not supported now", p);
1338                         break;
1339                 /* unknown option */
1340                 default:
1341                         if (!silent) {
1342                                 fat_msg(sb, KERN_ERR,
1343                                        "Unrecognized mount option \"%s\" "
1344                                        "or missing value", p);
1345                         }
1346                         return -EINVAL;
1347                 }
1348         }
1349
1350 out:
1351         /* UTF-8 doesn't provide FAT semantics */
1352         if (!strcmp(opts->iocharset, "utf8")) {
1353                 fat_msg(sb, KERN_WARNING, "utf8 is not a recommended IO charset"
1354                        " for FAT filesystems, filesystem will be "
1355                        "case sensitive!");
1356         }
1357
1358         /* If user doesn't specify allow_utime, it's initialized from dmask. */
1359         if (opts->allow_utime == (unsigned short)-1)
1360                 opts->allow_utime = ~opts->fs_dmask & (S_IWGRP | S_IWOTH);
1361         if (opts->unicode_xlate)
1362                 opts->utf8 = 0;
1363         if (opts->nfs == FAT_NFS_NOSTALE_RO) {
1364                 sb->s_flags |= SB_RDONLY;
1365                 sb->s_export_op = &fat_export_ops_nostale;
1366         }
1367
1368         return 0;
1369 }
1370
1371 static void fat_dummy_inode_init(struct inode *inode)
1372 {
1373         /* Initialize this dummy inode to work as no-op. */
1374         MSDOS_I(inode)->mmu_private = 0;
1375         MSDOS_I(inode)->i_start = 0;
1376         MSDOS_I(inode)->i_logstart = 0;
1377         MSDOS_I(inode)->i_attrs = 0;
1378         MSDOS_I(inode)->i_pos = 0;
1379 }
1380
1381 static int fat_read_root(struct inode *inode)
1382 {
1383         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
1384         int error;
1385
1386         MSDOS_I(inode)->i_pos = MSDOS_ROOT_INO;
1387         inode->i_uid = sbi->options.fs_uid;
1388         inode->i_gid = sbi->options.fs_gid;
1389         inode_inc_iversion(inode);
1390         inode->i_generation = 0;
1391         inode->i_mode = fat_make_mode(sbi, ATTR_DIR, S_IRWXUGO);
1392         inode->i_op = sbi->dir_ops;
1393         inode->i_fop = &fat_dir_operations;
1394         if (is_fat32(sbi)) {
1395                 MSDOS_I(inode)->i_start = sbi->root_cluster;
1396                 error = fat_calc_dir_size(inode);
1397                 if (error < 0)
1398                         return error;
1399         } else {
1400                 MSDOS_I(inode)->i_start = 0;
1401                 inode->i_size = sbi->dir_entries * sizeof(struct msdos_dir_entry);
1402         }
1403         inode->i_blocks = ((inode->i_size + (sbi->cluster_size - 1))
1404                            & ~((loff_t)sbi->cluster_size - 1)) >> 9;
1405         MSDOS_I(inode)->i_logstart = 0;
1406         MSDOS_I(inode)->mmu_private = inode->i_size;
1407
1408         fat_save_attrs(inode, ATTR_DIR);
1409         inode->i_mtime.tv_sec = inode->i_atime.tv_sec = inode->i_ctime.tv_sec = 0;
1410         inode->i_mtime.tv_nsec = inode->i_atime.tv_nsec = inode->i_ctime.tv_nsec = 0;
1411         set_nlink(inode, fat_subdirs(inode)+2);
1412
1413         return 0;
1414 }
1415
1416 static unsigned long calc_fat_clusters(struct super_block *sb)
1417 {
1418         struct msdos_sb_info *sbi = MSDOS_SB(sb);
1419
1420         /* Divide first to avoid overflow */
1421         if (!is_fat12(sbi)) {
1422                 unsigned long ent_per_sec = sb->s_blocksize * 8 / sbi->fat_bits;
1423                 return ent_per_sec * sbi->fat_length;
1424         }
1425
1426         return sbi->fat_length * sb->s_blocksize * 8 / sbi->fat_bits;
1427 }
1428
1429 static bool fat_bpb_is_zero(struct fat_boot_sector *b)
1430 {
1431         if (get_unaligned_le16(&b->sector_size))
1432                 return false;
1433         if (b->sec_per_clus)
1434                 return false;
1435         if (b->reserved)
1436                 return false;
1437         if (b->fats)
1438                 return false;
1439         if (get_unaligned_le16(&b->dir_entries))
1440                 return false;
1441         if (get_unaligned_le16(&b->sectors))
1442                 return false;
1443         if (b->media)
1444                 return false;
1445         if (b->fat_length)
1446                 return false;
1447         if (b->secs_track)
1448                 return false;
1449         if (b->heads)
1450                 return false;
1451         return true;
1452 }
1453
1454 static int fat_read_bpb(struct super_block *sb, struct fat_boot_sector *b,
1455         int silent, struct fat_bios_param_block *bpb)
1456 {
1457         int error = -EINVAL;
1458
1459         /* Read in BPB ... */
1460         memset(bpb, 0, sizeof(*bpb));
1461         bpb->fat_sector_size = get_unaligned_le16(&b->sector_size);
1462         bpb->fat_sec_per_clus = b->sec_per_clus;
1463         bpb->fat_reserved = le16_to_cpu(b->reserved);
1464         bpb->fat_fats = b->fats;
1465         bpb->fat_dir_entries = get_unaligned_le16(&b->dir_entries);
1466         bpb->fat_sectors = get_unaligned_le16(&b->sectors);
1467         bpb->fat_fat_length = le16_to_cpu(b->fat_length);
1468         bpb->fat_total_sect = le32_to_cpu(b->total_sect);
1469
1470         bpb->fat16_state = b->fat16.state;
1471         bpb->fat16_vol_id = get_unaligned_le32(b->fat16.vol_id);
1472
1473         bpb->fat32_length = le32_to_cpu(b->fat32.length);
1474         bpb->fat32_root_cluster = le32_to_cpu(b->fat32.root_cluster);
1475         bpb->fat32_info_sector = le16_to_cpu(b->fat32.info_sector);
1476         bpb->fat32_state = b->fat32.state;
1477         bpb->fat32_vol_id = get_unaligned_le32(b->fat32.vol_id);
1478
1479         /* Validate this looks like a FAT filesystem BPB */
1480         if (!bpb->fat_reserved) {
1481                 if (!silent)
1482                         fat_msg(sb, KERN_ERR,
1483                                 "bogus number of reserved sectors");
1484                 goto out;
1485         }
1486         if (!bpb->fat_fats) {
1487                 if (!silent)
1488                         fat_msg(sb, KERN_ERR, "bogus number of FAT structure");
1489                 goto out;
1490         }
1491
1492         /*
1493          * Earlier we checked here that b->secs_track and b->head are nonzero,
1494          * but it turns out valid FAT filesystems can have zero there.
1495          */
1496
1497         if (!fat_valid_media(b->media)) {
1498                 if (!silent)
1499                         fat_msg(sb, KERN_ERR, "invalid media value (0x%02x)",
1500                                 (unsigned)b->media);
1501                 goto out;
1502         }
1503
1504         if (!is_power_of_2(bpb->fat_sector_size)
1505             || (bpb->fat_sector_size < 512)
1506             || (bpb->fat_sector_size > 4096)) {
1507                 if (!silent)
1508                         fat_msg(sb, KERN_ERR, "bogus logical sector size %u",
1509                                (unsigned)bpb->fat_sector_size);
1510                 goto out;
1511         }
1512
1513         if (!is_power_of_2(bpb->fat_sec_per_clus)) {
1514                 if (!silent)
1515                         fat_msg(sb, KERN_ERR, "bogus sectors per cluster %u",
1516                                 (unsigned)bpb->fat_sec_per_clus);
1517                 goto out;
1518         }
1519
1520         error = 0;
1521
1522 out:
1523         return error;
1524 }
1525
1526 static int fat_read_static_bpb(struct super_block *sb,
1527         struct fat_boot_sector *b, int silent,
1528         struct fat_bios_param_block *bpb)
1529 {
1530         static const char *notdos1x = "This doesn't look like a DOS 1.x volume";
1531
1532         struct fat_floppy_defaults *fdefaults = NULL;
1533         int error = -EINVAL;
1534         sector_t bd_sects;
1535         unsigned i;
1536
1537         bd_sects = i_size_read(sb->s_bdev->bd_inode) / SECTOR_SIZE;
1538
1539         /* 16-bit DOS 1.x reliably wrote bootstrap short-jmp code */
1540         if (b->ignored[0] != 0xeb || b->ignored[2] != 0x90) {
1541                 if (!silent)
1542                         fat_msg(sb, KERN_ERR,
1543                                 "%s; no bootstrapping code", notdos1x);
1544                 goto out;
1545         }
1546
1547         /*
1548          * If any value in this region is non-zero, it isn't archaic
1549          * DOS.
1550          */
1551         if (!fat_bpb_is_zero(b)) {
1552                 if (!silent)
1553                         fat_msg(sb, KERN_ERR,
1554                                 "%s; DOS 2.x BPB is non-zero", notdos1x);
1555                 goto out;
1556         }
1557
1558         for (i = 0; i < ARRAY_SIZE(floppy_defaults); i++) {
1559                 if (floppy_defaults[i].nr_sectors == bd_sects) {
1560                         fdefaults = &floppy_defaults[i];
1561                         break;
1562                 }
1563         }
1564
1565         if (fdefaults == NULL) {
1566                 if (!silent)
1567                         fat_msg(sb, KERN_WARNING,
1568                                 "This looks like a DOS 1.x volume, but isn't a recognized floppy size (%llu sectors)",
1569                                 (u64)bd_sects);
1570                 goto out;
1571         }
1572
1573         if (!silent)
1574                 fat_msg(sb, KERN_INFO,
1575                         "This looks like a DOS 1.x volume; assuming default BPB values");
1576
1577         memset(bpb, 0, sizeof(*bpb));
1578         bpb->fat_sector_size = SECTOR_SIZE;
1579         bpb->fat_sec_per_clus = fdefaults->sec_per_clus;
1580         bpb->fat_reserved = 1;
1581         bpb->fat_fats = 2;
1582         bpb->fat_dir_entries = fdefaults->dir_entries;
1583         bpb->fat_sectors = fdefaults->nr_sectors;
1584         bpb->fat_fat_length = fdefaults->fat_length;
1585
1586         error = 0;
1587
1588 out:
1589         return error;
1590 }
1591
1592 /*
1593  * Read the super block of an MS-DOS FS.
1594  */
1595 int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat,
1596                    void (*setup)(struct super_block *))
1597 {
1598         struct inode *root_inode = NULL, *fat_inode = NULL;
1599         struct inode *fsinfo_inode = NULL;
1600         struct buffer_head *bh;
1601         struct fat_bios_param_block bpb;
1602         struct msdos_sb_info *sbi;
1603         u16 logical_sector_size;
1604         u32 total_sectors, total_clusters, fat_clusters, rootdir_sectors;
1605         int debug;
1606         long error;
1607         char buf[50];
1608
1609         /*
1610          * GFP_KERNEL is ok here, because while we do hold the
1611          * superblock lock, memory pressure can't call back into
1612          * the filesystem, since we're only just about to mount
1613          * it and have no inodes etc active!
1614          */
1615         sbi = kzalloc(sizeof(struct msdos_sb_info), GFP_KERNEL);
1616         if (!sbi)
1617                 return -ENOMEM;
1618         sb->s_fs_info = sbi;
1619
1620         sb->s_flags |= SB_NODIRATIME;
1621         sb->s_magic = MSDOS_SUPER_MAGIC;
1622         sb->s_op = &fat_sops;
1623         sb->s_export_op = &fat_export_ops;
1624         /*
1625          * fat timestamps are complex and truncated by fat itself, so
1626          * we set 1 here to be fast
1627          */
1628         sb->s_time_gran = 1;
1629         mutex_init(&sbi->nfs_build_inode_lock);
1630         ratelimit_state_init(&sbi->ratelimit, DEFAULT_RATELIMIT_INTERVAL,
1631                              DEFAULT_RATELIMIT_BURST);
1632
1633         error = parse_options(sb, data, isvfat, silent, &debug, &sbi->options);
1634         if (error)
1635                 goto out_fail;
1636
1637         setup(sb); /* flavour-specific stuff that needs options */
1638
1639         error = -EIO;
1640         sb_min_blocksize(sb, 512);
1641         bh = sb_bread(sb, 0);
1642         if (bh == NULL) {
1643                 fat_msg(sb, KERN_ERR, "unable to read boot sector");
1644                 goto out_fail;
1645         }
1646
1647         error = fat_read_bpb(sb, (struct fat_boot_sector *)bh->b_data, silent,
1648                 &bpb);
1649         if (error == -EINVAL && sbi->options.dos1xfloppy)
1650                 error = fat_read_static_bpb(sb,
1651                         (struct fat_boot_sector *)bh->b_data, silent, &bpb);
1652         brelse(bh);
1653
1654         if (error == -EINVAL)
1655                 goto out_invalid;
1656         else if (error)
1657                 goto out_fail;
1658
1659         logical_sector_size = bpb.fat_sector_size;
1660         sbi->sec_per_clus = bpb.fat_sec_per_clus;
1661
1662         error = -EIO;
1663         if (logical_sector_size < sb->s_blocksize) {
1664                 fat_msg(sb, KERN_ERR, "logical sector size too small for device"
1665                        " (logical sector size = %u)", logical_sector_size);
1666                 goto out_fail;
1667         }
1668
1669         if (logical_sector_size > sb->s_blocksize) {
1670                 struct buffer_head *bh_resize;
1671
1672                 if (!sb_set_blocksize(sb, logical_sector_size)) {
1673                         fat_msg(sb, KERN_ERR, "unable to set blocksize %u",
1674                                logical_sector_size);
1675                         goto out_fail;
1676                 }
1677
1678                 /* Verify that the larger boot sector is fully readable */
1679                 bh_resize = sb_bread(sb, 0);
1680                 if (bh_resize == NULL) {
1681                         fat_msg(sb, KERN_ERR, "unable to read boot sector"
1682                                " (logical sector size = %lu)",
1683                                sb->s_blocksize);
1684                         goto out_fail;
1685                 }
1686                 brelse(bh_resize);
1687         }
1688
1689         mutex_init(&sbi->s_lock);
1690         sbi->cluster_size = sb->s_blocksize * sbi->sec_per_clus;
1691         sbi->cluster_bits = ffs(sbi->cluster_size) - 1;
1692         sbi->fats = bpb.fat_fats;
1693         sbi->fat_bits = 0;              /* Don't know yet */
1694         sbi->fat_start = bpb.fat_reserved;
1695         sbi->fat_length = bpb.fat_fat_length;
1696         sbi->root_cluster = 0;
1697         sbi->free_clusters = -1;        /* Don't know yet */
1698         sbi->free_clus_valid = 0;
1699         sbi->prev_free = FAT_START_ENT;
1700         sb->s_maxbytes = 0xffffffff;
1701
1702         if (!sbi->fat_length && bpb.fat32_length) {
1703                 struct fat_boot_fsinfo *fsinfo;
1704                 struct buffer_head *fsinfo_bh;
1705
1706                 /* Must be FAT32 */
1707                 sbi->fat_bits = 32;
1708                 sbi->fat_length = bpb.fat32_length;
1709                 sbi->root_cluster = bpb.fat32_root_cluster;
1710
1711                 /* MC - if info_sector is 0, don't multiply by 0 */
1712                 sbi->fsinfo_sector = bpb.fat32_info_sector;
1713                 if (sbi->fsinfo_sector == 0)
1714                         sbi->fsinfo_sector = 1;
1715
1716                 fsinfo_bh = sb_bread(sb, sbi->fsinfo_sector);
1717                 if (fsinfo_bh == NULL) {
1718                         fat_msg(sb, KERN_ERR, "bread failed, FSINFO block"
1719                                " (sector = %lu)", sbi->fsinfo_sector);
1720                         goto out_fail;
1721                 }
1722
1723                 fsinfo = (struct fat_boot_fsinfo *)fsinfo_bh->b_data;
1724                 if (!IS_FSINFO(fsinfo)) {
1725                         fat_msg(sb, KERN_WARNING, "Invalid FSINFO signature: "
1726                                "0x%08x, 0x%08x (sector = %lu)",
1727                                le32_to_cpu(fsinfo->signature1),
1728                                le32_to_cpu(fsinfo->signature2),
1729                                sbi->fsinfo_sector);
1730                 } else {
1731                         if (sbi->options.usefree)
1732                                 sbi->free_clus_valid = 1;
1733                         sbi->free_clusters = le32_to_cpu(fsinfo->free_clusters);
1734                         sbi->prev_free = le32_to_cpu(fsinfo->next_cluster);
1735                 }
1736
1737                 brelse(fsinfo_bh);
1738         }
1739
1740         /* interpret volume ID as a little endian 32 bit integer */
1741         if (is_fat32(sbi))
1742                 sbi->vol_id = bpb.fat32_vol_id;
1743         else /* fat 16 or 12 */
1744                 sbi->vol_id = bpb.fat16_vol_id;
1745
1746         sbi->dir_per_block = sb->s_blocksize / sizeof(struct msdos_dir_entry);
1747         sbi->dir_per_block_bits = ffs(sbi->dir_per_block) - 1;
1748
1749         sbi->dir_start = sbi->fat_start + sbi->fats * sbi->fat_length;
1750         sbi->dir_entries = bpb.fat_dir_entries;
1751         if (sbi->dir_entries & (sbi->dir_per_block - 1)) {
1752                 if (!silent)
1753                         fat_msg(sb, KERN_ERR, "bogus number of directory entries"
1754                                " (%u)", sbi->dir_entries);
1755                 goto out_invalid;
1756         }
1757
1758         rootdir_sectors = sbi->dir_entries
1759                 * sizeof(struct msdos_dir_entry) / sb->s_blocksize;
1760         sbi->data_start = sbi->dir_start + rootdir_sectors;
1761         total_sectors = bpb.fat_sectors;
1762         if (total_sectors == 0)
1763                 total_sectors = bpb.fat_total_sect;
1764
1765         total_clusters = (total_sectors - sbi->data_start) / sbi->sec_per_clus;
1766
1767         if (!is_fat32(sbi))
1768                 sbi->fat_bits = (total_clusters > MAX_FAT12) ? 16 : 12;
1769
1770         /* some OSes set FAT_STATE_DIRTY and clean it on unmount. */
1771         if (is_fat32(sbi))
1772                 sbi->dirty = bpb.fat32_state & FAT_STATE_DIRTY;
1773         else /* fat 16 or 12 */
1774                 sbi->dirty = bpb.fat16_state & FAT_STATE_DIRTY;
1775
1776         /* check that FAT table does not overflow */
1777         fat_clusters = calc_fat_clusters(sb);
1778         total_clusters = min(total_clusters, fat_clusters - FAT_START_ENT);
1779         if (total_clusters > max_fat(sb)) {
1780                 if (!silent)
1781                         fat_msg(sb, KERN_ERR, "count of clusters too big (%u)",
1782                                total_clusters);
1783                 goto out_invalid;
1784         }
1785
1786         sbi->max_cluster = total_clusters + FAT_START_ENT;
1787         /* check the free_clusters, it's not necessarily correct */
1788         if (sbi->free_clusters != -1 && sbi->free_clusters > total_clusters)
1789                 sbi->free_clusters = -1;
1790         /* check the prev_free, it's not necessarily correct */
1791         sbi->prev_free %= sbi->max_cluster;
1792         if (sbi->prev_free < FAT_START_ENT)
1793                 sbi->prev_free = FAT_START_ENT;
1794
1795         /* set up enough so that it can read an inode */
1796         fat_hash_init(sb);
1797         dir_hash_init(sb);
1798         fat_ent_access_init(sb);
1799
1800         /*
1801          * The low byte of the first FAT entry must have the same value as
1802          * the media field of the boot sector. But in real world, too many
1803          * devices are writing wrong values. So, removed that validity check.
1804          *
1805          * The removed check compared the first FAT entry to a value dependent
1806          * on the media field like this:
1807          * == (0x0F00 | media), for FAT12
1808          * == (0XFF00 | media), for FAT16
1809          * == (0x0FFFFF | media), for FAT32
1810          */
1811
1812         error = -EINVAL;
1813         sprintf(buf, "cp%d", sbi->options.codepage);
1814         sbi->nls_disk = load_nls(buf);
1815         if (!sbi->nls_disk) {
1816                 fat_msg(sb, KERN_ERR, "codepage %s not found", buf);
1817                 goto out_fail;
1818         }
1819
1820         /* FIXME: utf8 is using iocharset for upper/lower conversion */
1821         if (sbi->options.isvfat) {
1822                 sbi->nls_io = load_nls(sbi->options.iocharset);
1823                 if (!sbi->nls_io) {
1824                         fat_msg(sb, KERN_ERR, "IO charset %s not found",
1825                                sbi->options.iocharset);
1826                         goto out_fail;
1827                 }
1828         }
1829
1830         error = -ENOMEM;
1831         fat_inode = new_inode(sb);
1832         if (!fat_inode)
1833                 goto out_fail;
1834         fat_dummy_inode_init(fat_inode);
1835         sbi->fat_inode = fat_inode;
1836
1837         fsinfo_inode = new_inode(sb);
1838         if (!fsinfo_inode)
1839                 goto out_fail;
1840         fat_dummy_inode_init(fsinfo_inode);
1841         fsinfo_inode->i_ino = MSDOS_FSINFO_INO;
1842         sbi->fsinfo_inode = fsinfo_inode;
1843         insert_inode_hash(fsinfo_inode);
1844
1845         root_inode = new_inode(sb);
1846         if (!root_inode)
1847                 goto out_fail;
1848         root_inode->i_ino = MSDOS_ROOT_INO;
1849         inode_set_iversion(root_inode, 1);
1850         error = fat_read_root(root_inode);
1851         if (error < 0) {
1852                 iput(root_inode);
1853                 goto out_fail;
1854         }
1855         error = -ENOMEM;
1856         insert_inode_hash(root_inode);
1857         fat_attach(root_inode, 0);
1858         sb->s_root = d_make_root(root_inode);
1859         if (!sb->s_root) {
1860                 fat_msg(sb, KERN_ERR, "get root inode failed");
1861                 goto out_fail;
1862         }
1863
1864         if (sbi->options.discard) {
1865                 struct request_queue *q = bdev_get_queue(sb->s_bdev);
1866                 if (!blk_queue_discard(q))
1867                         fat_msg(sb, KERN_WARNING,
1868                                         "mounting with \"discard\" option, but "
1869                                         "the device does not support discard");
1870         }
1871
1872         fat_set_state(sb, 1, 0);
1873         return 0;
1874
1875 out_invalid:
1876         error = -EINVAL;
1877         if (!silent)
1878                 fat_msg(sb, KERN_INFO, "Can't find a valid FAT filesystem");
1879
1880 out_fail:
1881         if (fsinfo_inode)
1882                 iput(fsinfo_inode);
1883         if (fat_inode)
1884                 iput(fat_inode);
1885         unload_nls(sbi->nls_io);
1886         unload_nls(sbi->nls_disk);
1887         fat_reset_iocharset(&sbi->options);
1888         sb->s_fs_info = NULL;
1889         kfree(sbi);
1890         return error;
1891 }
1892
1893 EXPORT_SYMBOL_GPL(fat_fill_super);
1894
1895 /*
1896  * helper function for fat_flush_inodes.  This writes both the inode
1897  * and the file data blocks, waiting for in flight data blocks before
1898  * the start of the call.  It does not wait for any io started
1899  * during the call
1900  */
1901 static int writeback_inode(struct inode *inode)
1902 {
1903
1904         int ret;
1905
1906         /* if we used wait=1, sync_inode_metadata waits for the io for the
1907         * inode to finish.  So wait=0 is sent down to sync_inode_metadata
1908         * and filemap_fdatawrite is used for the data blocks
1909         */
1910         ret = sync_inode_metadata(inode, 0);
1911         if (!ret)
1912                 ret = filemap_fdatawrite(inode->i_mapping);
1913         return ret;
1914 }
1915
1916 /*
1917  * write data and metadata corresponding to i1 and i2.  The io is
1918  * started but we do not wait for any of it to finish.
1919  *
1920  * filemap_flush is used for the block device, so if there is a dirty
1921  * page for a block already in flight, we will not wait and start the
1922  * io over again
1923  */
1924 int fat_flush_inodes(struct super_block *sb, struct inode *i1, struct inode *i2)
1925 {
1926         int ret = 0;
1927         if (!MSDOS_SB(sb)->options.flush)
1928                 return 0;
1929         if (i1)
1930                 ret = writeback_inode(i1);
1931         if (!ret && i2)
1932                 ret = writeback_inode(i2);
1933         if (!ret) {
1934                 struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping;
1935                 ret = filemap_flush(mapping);
1936         }
1937         return ret;
1938 }
1939 EXPORT_SYMBOL_GPL(fat_flush_inodes);
1940
1941 static int __init init_fat_fs(void)
1942 {
1943         int err;
1944
1945         err = fat_cache_init();
1946         if (err)
1947                 return err;
1948
1949         err = fat_init_inodecache();
1950         if (err)
1951                 goto failed;
1952
1953         return 0;
1954
1955 failed:
1956         fat_cache_destroy();
1957         return err;
1958 }
1959
1960 static void __exit exit_fat_fs(void)
1961 {
1962         fat_cache_destroy();
1963         fat_destroy_inodecache();
1964 }
1965
1966 module_init(init_fat_fs)
1967 module_exit(exit_fat_fs)
1968
1969 MODULE_LICENSE("GPL");