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/random.h>
  25 #include <linux/iversion.h>
  26 #include "fat.h"
  27
  28 #ifndef CONFIG_FAT_DEFAULT_IOCHARSET
  29 /* if user don't select VFAT, this is undefined. */
  30 #define CONFIG_FAT_DEFAULT_IOCHARSET    ""
  31 #endif
  32
  33 #define KB_IN_SECTORS 2
  34
  35 /* DOS dates from 1980/1/1 through 2107/12/31 */
  36 #define FAT_DATE_MIN (0<<9 | 1<<5 | 1)
  37 #define FAT_DATE_MAX (127<<9 | 12<<5 | 31)
  38 #define FAT_TIME_MAX (23<<11 | 59<<5 | 29)
  39
  40 /*
  41  * A deserialized copy of the on-disk structure laid out in struct
  42  * fat_boot_sector.
  43  */
  44 struct fat_bios_param_block {
  45         u16     fat_sector_size;
  46         u8      fat_sec_per_clus;
  47         u16     fat_reserved;
  48         u8      fat_fats;
  49         u16     fat_dir_entries;
  50         u16     fat_sectors;
  51         u16     fat_fat_length;
  52         u32     fat_total_sect;
  53
  54         u8      fat16_state;
  55         u32     fat16_vol_id;
  56
  57         u32     fat32_length;
  58         u32     fat32_root_cluster;
  59         u16     fat32_info_sector;
  60         u8      fat32_state;
  61         u32     fat32_vol_id;
  62 };
  63
  64 static int fat_default_codepage = CONFIG_FAT_DEFAULT_CODEPAGE;
  65 static char fat_default_iocharset[] = CONFIG_FAT_DEFAULT_IOCHARSET;
  66
  67 static struct fat_floppy_defaults {
  68         unsigned nr_sectors;
  69         unsigned sec_per_clus;
  70         unsigned dir_entries;
  71         unsigned media;
  72         unsigned fat_length;
  73 } floppy_defaults[] = {
  74 {
  75         .nr_sectors = 160 * KB_IN_SECTORS,
  76         .sec_per_clus = 1,
  77         .dir_entries = 64,
  78         .media = 0xFE,
  79         .fat_length = 1,
  80 },
  81 {
  82         .nr_sectors = 180 * KB_IN_SECTORS,
  83         .sec_per_clus = 1,
  84         .dir_entries = 64,
  85         .media = 0xFC,
  86         .fat_length = 2,
  87 },
  88 {
  89         .nr_sectors = 320 * KB_IN_SECTORS,
  90         .sec_per_clus = 2,
  91         .dir_entries = 112,
  92         .media = 0xFF,
  93         .fat_length = 1,
  94 },
  95 {
  96         .nr_sectors = 360 * KB_IN_SECTORS,
  97         .sec_per_clus = 2,
  98         .dir_entries = 112,
  99         .media = 0xFD,
 100         .fat_length = 2,
 101 },
 102 };
 103
 104 int fat_add_cluster(struct inode *inode)
 105 {
 106         int err, cluster;
 107
 108         err = fat_alloc_clusters(inode, &cluster, 1);
 109         if (err)
 110                 return err;
 111         /* FIXME: this cluster should be added after data of this
 112          * cluster is writed */
 113         err = fat_chain_add(inode, cluster, 1);
 114         if (err)
 115                 fat_free_clusters(inode, cluster);
 116         return err;
 117 }
 118
 119 static inline int __fat_get_block(struct inode *inode, sector_t iblock,
 120                                   unsigned long *max_blocks,
 121                                   struct buffer_head *bh_result, int create)
 122 {
 123         struct super_block *sb = inode->i_sb;
 124         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 125         unsigned long mapped_blocks;
 126         sector_t phys, last_block;
 127         int err, offset;
 128
 129         err = fat_bmap(inode, iblock, &phys, &mapped_blocks, create, false);
 130         if (err)
 131                 return err;
 132         if (phys) {
 133                 map_bh(bh_result, sb, phys);
 134                 *max_blocks = min(mapped_blocks, *max_blocks);
 135                 return 0;
 136         }
 137         if (!create)
 138                 return 0;
 139
 140         if (iblock != MSDOS_I(inode)->mmu_private >> sb->s_blocksize_bits) {
 141                 fat_fs_error(sb, "corrupted file size (i_pos %lld, %lld)",
 142                         MSDOS_I(inode)->i_pos, MSDOS_I(inode)->mmu_private);
 143                 return -EIO;
 144         }
 145
 146         last_block = inode->i_blocks >> (sb->s_blocksize_bits - 9);
 147         offset = (unsigned long)iblock & (sbi->sec_per_clus - 1);
 148         /*
 149          * allocate a cluster according to the following.
 150          * 1) no more available blocks
 151          * 2) not part of fallocate region
 152          */
 153         if (!offset && !(iblock < last_block)) {
 154                 /* TODO: multiple cluster allocation would be desirable. */
 155                 err = fat_add_cluster(inode);
 156                 if (err)
 157                         return err;
 158         }
 159         /* available blocks on this cluster */
 160         mapped_blocks = sbi->sec_per_clus - offset;
 161
 162         *max_blocks = min(mapped_blocks, *max_blocks);
 163         MSDOS_I(inode)->mmu_private += *max_blocks << sb->s_blocksize_bits;
 164
 165         err = fat_bmap(inode, iblock, &phys, &mapped_blocks, create, false);
 166         if (err)
 167                 return err;
 168         if (!phys) {
 169                 fat_fs_error(sb,
 170                              "invalid FAT chain (i_pos %lld, last_block %llu)",
 171                              MSDOS_I(inode)->i_pos,
 172                              (unsigned long long)last_block);
 173                 return -EIO;
 174         }
 175
 176         BUG_ON(*max_blocks != mapped_blocks);
 177         set_buffer_new(bh_result);
 178         map_bh(bh_result, sb, phys);
 179
 180         return 0;
 181 }
 182
 183 static int fat_get_block(struct inode *inode, sector_t iblock,
 184                          struct buffer_head *bh_result, int create)
 185 {
 186         struct super_block *sb = inode->i_sb;
 187         unsigned long max_blocks = bh_result->b_size >> inode->i_blkbits;
 188         int err;
 189
 190         err = __fat_get_block(inode, iblock, &max_blocks, bh_result, create);
 191         if (err)
 192                 return err;
 193         bh_result->b_size = max_blocks << sb->s_blocksize_bits;
 194         return 0;
 195 }
 196
 197 static int fat_writepage(struct page *page, struct writeback_control *wbc)
 198 {
 199         return block_write_full_page(page, fat_get_block, wbc);
 200 }
 201
 202 static int fat_writepages(struct address_space *mapping,
 203                           struct writeback_control *wbc)
 204 {
 205         return mpage_writepages(mapping, wbc, fat_get_block);
 206 }
 207
 208 static int fat_readpage(struct file *file, struct page *page)
 209 {
 210         return mpage_readpage(page, fat_get_block);
 211 }
 212
 213 static int fat_readpages(struct file *file, struct address_space *mapping,
 214                          struct list_head *pages, unsigned nr_pages)
 215 {
 216         return mpage_readpages(mapping, pages, nr_pages, fat_get_block);
 217 }
 218
 219 static void fat_write_failed(struct address_space *mapping, loff_t to)
 220 {
 221         struct inode *inode = mapping->host;
 222
 223         if (to > inode->i_size) {
 224                 truncate_pagecache(inode, inode->i_size);
 225                 fat_truncate_blocks(inode, inode->i_size);
 226         }
 227 }
 228
 229 static int fat_write_begin(struct file *file, struct address_space *mapping,
 230                         loff_t pos, unsigned len, unsigned flags,
 231                         struct page **pagep, void **fsdata)
 232 {
 233         int err;
 234
 235         *pagep = NULL;
 236         err = cont_write_begin(file, mapping, pos, len, flags,
 237                                 pagep, fsdata, fat_get_block,
 238                                 &MSDOS_I(mapping->host)->mmu_private);
 239         if (err < 0)
 240                 fat_write_failed(mapping, pos + len);
 241         return err;
 242 }
 243
 244 static int fat_write_end(struct file *file, struct address_space *mapping,
 245                         loff_t pos, unsigned len, unsigned copied,
 246                         struct page *pagep, void *fsdata)
 247 {
 248         struct inode *inode = mapping->host;
 249         int err;
 250         err = generic_write_end(file, mapping, pos, len, copied, pagep, fsdata);
 251         if (err < len)
 252                 fat_write_failed(mapping, pos + len);
 253         if (!(err < 0) && !(MSDOS_I(inode)->i_attrs & ATTR_ARCH)) {
 254                 fat_truncate_time(inode, NULL, S_CTIME|S_MTIME);
 255                 MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
 256                 mark_inode_dirty(inode);
 257         }
 258         return err;
 259 }
 260
 261 static ssize_t fat_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
 262 {
 263         struct file *file = iocb->ki_filp;
 264         struct address_space *mapping = file->f_mapping;
 265         struct inode *inode = mapping->host;
 266         size_t count = iov_iter_count(iter);
 267         loff_t offset = iocb->ki_pos;
 268         ssize_t ret;
 269
 270         if (iov_iter_rw(iter) == WRITE) {
 271                 /*
 272                  * FIXME: blockdev_direct_IO() doesn't use ->write_begin(),
 273                  * so we need to update the ->mmu_private to block boundary.
 274                  *
 275                  * But we must fill the remaining area or hole by nul for
 276                  * updating ->mmu_private.
 277                  *
 278                  * Return 0, and fallback to normal buffered write.
 279                  */
 280                 loff_t size = offset + count;
 281                 if (MSDOS_I(inode)->mmu_private < size)
 282                         return 0;
 283         }
 284
 285         /*
 286          * FAT need to use the DIO_LOCKING for avoiding the race
 287          * condition of fat_get_block() and ->truncate().
 288          */
 289         ret = blockdev_direct_IO(iocb, inode, iter, fat_get_block);
 290         if (ret < 0 && iov_iter_rw(iter) == WRITE)
 291                 fat_write_failed(mapping, offset + count);
 292
 293         return ret;
 294 }
 295
 296 static int fat_get_block_bmap(struct inode *inode, sector_t iblock,
 297                 struct buffer_head *bh_result, int create)
 298 {
 299         struct super_block *sb = inode->i_sb;
 300         unsigned long max_blocks = bh_result->b_size >> inode->i_blkbits;
 301         int err;
 302         sector_t bmap;
 303         unsigned long mapped_blocks;
 304
 305         BUG_ON(create != 0);
 306
 307         err = fat_bmap(inode, iblock, &bmap, &mapped_blocks, create, true);
 308         if (err)
 309                 return err;
 310
 311         if (bmap) {
 312                 map_bh(bh_result, sb, bmap);
 313                 max_blocks = min(mapped_blocks, max_blocks);
 314         }
 315
 316         bh_result->b_size = max_blocks << sb->s_blocksize_bits;
 317
 318         return 0;
 319 }
 320
 321 static sector_t _fat_bmap(struct address_space *mapping, sector_t block)
 322 {
 323         sector_t blocknr;
 324
 325         /* fat_get_cluster() assumes the requested blocknr isn't truncated. */
 326         down_read(&MSDOS_I(mapping->host)->truncate_lock);
 327         blocknr = generic_block_bmap(mapping, block, fat_get_block_bmap);
 328         up_read(&MSDOS_I(mapping->host)->truncate_lock);
 329
 330         return blocknr;
 331 }
 332
 333 /*
 334  * fat_block_truncate_page() zeroes out a mapping from file offset `from'
 335  * up to the end of the block which corresponds to `from'.
 336  * This is required during truncate to physically zeroout the tail end
 337  * of that block so it doesn't yield old data if the file is later grown.
 338  * Also, avoid causing failure from fsx for cases of "data past EOF"
 339  */
 340 int fat_block_truncate_page(struct inode *inode, loff_t from)
 341 {
 342         return block_truncate_page(inode->i_mapping, from, fat_get_block);
 343 }
 344
 345 static const struct address_space_operations fat_aops = {
 346         .readpage       = fat_readpage,
 347         .readpages      = fat_readpages,
 348         .writepage      = fat_writepage,
 349         .writepages     = fat_writepages,
 350         .write_begin    = fat_write_begin,
 351         .write_end      = fat_write_end,
 352         .direct_IO      = fat_direct_IO,
 353         .bmap           = _fat_bmap
 354 };
 355
 356 /*
 357  * New FAT inode stuff. We do the following:
 358  *      a) i_ino is constant and has nothing with on-disk location.
 359  *      b) FAT manages its own cache of directory entries.
 360  *      c) *This* cache is indexed by on-disk location.
 361  *      d) inode has an associated directory entry, all right, but
 362  *              it may be unhashed.
 363  *      e) currently entries are stored within struct inode. That should
 364  *              change.
 365  *      f) we deal with races in the following way:
 366  *              1. readdir() and lookup() do FAT-dir-cache lookup.
 367  *              2. rename() unhashes the F-d-c entry and rehashes it in
 368  *                      a new place.
 369  *              3. unlink() and rmdir() unhash F-d-c entry.
 370  *              4. fat_write_inode() checks whether the thing is unhashed.
 371  *                      If it is we silently return. If it isn't we do bread(),
 372  *                      check if the location is still valid and retry if it
 373  *                      isn't. Otherwise we do changes.
 374  *              5. Spinlock is used to protect hash/unhash/location check/lookup
 375  *              6. fat_evict_inode() unhashes the F-d-c entry.
 376  *              7. lookup() and readdir() do igrab() if they find a F-d-c entry
 377  *                      and consider negative result as cache miss.
 378  */
 379
 380 static void fat_hash_init(struct super_block *sb)
 381 {
 382         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 383         int i;
 384
 385         spin_lock_init(&sbi->inode_hash_lock);
 386         for (i = 0; i < FAT_HASH_SIZE; i++)
 387                 INIT_HLIST_HEAD(&sbi->inode_hashtable[i]);
 388 }
 389
 390 static inline unsigned long fat_hash(loff_t i_pos)
 391 {
 392         return hash_32(i_pos, FAT_HASH_BITS);
 393 }
 394
 395 static void dir_hash_init(struct super_block *sb)
 396 {
 397         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 398         int i;
 399
 400         spin_lock_init(&sbi->dir_hash_lock);
 401         for (i = 0; i < FAT_HASH_SIZE; i++)
 402                 INIT_HLIST_HEAD(&sbi->dir_hashtable[i]);
 403 }
 404
 405 void fat_attach(struct inode *inode, loff_t i_pos)
 406 {
 407         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 408
 409         if (inode->i_ino != MSDOS_ROOT_INO) {
 410                 struct hlist_head *head =   sbi->inode_hashtable
 411                                           + fat_hash(i_pos);
 412
 413                 spin_lock(&sbi->inode_hash_lock);
 414                 MSDOS_I(inode)->i_pos = i_pos;
 415                 hlist_add_head(&MSDOS_I(inode)->i_fat_hash, head);
 416                 spin_unlock(&sbi->inode_hash_lock);
 417         }
 418
 419         /* If NFS support is enabled, cache the mapping of start cluster
 420          * to directory inode. This is used during reconnection of
 421          * dentries to the filesystem root.
 422          */
 423         if (S_ISDIR(inode->i_mode) && sbi->options.nfs) {
 424                 struct hlist_head *d_head = sbi->dir_hashtable;
 425                 d_head += fat_dir_hash(MSDOS_I(inode)->i_logstart);
 426
 427                 spin_lock(&sbi->dir_hash_lock);
 428                 hlist_add_head(&MSDOS_I(inode)->i_dir_hash, d_head);
 429                 spin_unlock(&sbi->dir_hash_lock);
 430         }
 431 }
 432 EXPORT_SYMBOL_GPL(fat_attach);
 433
 434 void fat_detach(struct inode *inode)
 435 {
 436         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 437         spin_lock(&sbi->inode_hash_lock);
 438         MSDOS_I(inode)->i_pos = 0;
 439         hlist_del_init(&MSDOS_I(inode)->i_fat_hash);
 440         spin_unlock(&sbi->inode_hash_lock);
 441
 442         if (S_ISDIR(inode->i_mode) && sbi->options.nfs) {
 443                 spin_lock(&sbi->dir_hash_lock);
 444                 hlist_del_init(&MSDOS_I(inode)->i_dir_hash);
 445                 spin_unlock(&sbi->dir_hash_lock);
 446         }
 447 }
 448 EXPORT_SYMBOL_GPL(fat_detach);
 449
 450 struct inode *fat_iget(struct super_block *sb, loff_t i_pos)
 451 {
 452         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 453         struct hlist_head *head = sbi->inode_hashtable + fat_hash(i_pos);
 454         struct msdos_inode_info *i;
 455         struct inode *inode = NULL;
 456
 457         spin_lock(&sbi->inode_hash_lock);
 458         hlist_for_each_entry(i, head, i_fat_hash) {
 459                 BUG_ON(i->vfs_inode.i_sb != sb);
 460                 if (i->i_pos != i_pos)
 461                         continue;
 462                 inode = igrab(&i->vfs_inode);
 463                 if (inode)
 464                         break;
 465         }
 466         spin_unlock(&sbi->inode_hash_lock);
 467         return inode;
 468 }
 469
 470 static int is_exec(unsigned char *extension)
 471 {
 472         unsigned char exe_extensions[] = "EXECOMBAT", *walk;
 473
 474         for (walk = exe_extensions; *walk; walk += 3)
 475                 if (!strncmp(extension, walk, 3))
 476                         return 1;
 477         return 0;
 478 }
 479
 480 static int fat_calc_dir_size(struct inode *inode)
 481 {
 482         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 483         int ret, fclus, dclus;
 484
 485         inode->i_size = 0;
 486         if (MSDOS_I(inode)->i_start == 0)
 487                 return 0;
 488
 489         ret = fat_get_cluster(inode, FAT_ENT_EOF, &fclus, &dclus);
 490         if (ret < 0)
 491                 return ret;
 492         inode->i_size = (fclus + 1) << sbi->cluster_bits;
 493
 494         return 0;
 495 }
 496
 497 static int fat_validate_dir(struct inode *dir)
 498 {
 499         struct super_block *sb = dir->i_sb;
 500
 501         if (dir->i_nlink < 2) {
 502                 /* Directory should have "."/".." entries at least. */
 503                 fat_fs_error(sb, "corrupted directory (invalid entries)");
 504                 return -EIO;
 505         }
 506         if (MSDOS_I(dir)->i_start == 0 ||
 507             MSDOS_I(dir)->i_start == MSDOS_SB(sb)->root_cluster) {
 508                 /* Directory should point valid cluster. */
 509                 fat_fs_error(sb, "corrupted directory (invalid i_start)");
 510                 return -EIO;
 511         }
 512         return 0;
 513 }
 514
 515 /* doesn't deal with root inode */
 516 int fat_fill_inode(struct inode *inode, struct msdos_dir_entry *de)
 517 {
 518         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 519         int error;
 520
 521         MSDOS_I(inode)->i_pos = 0;
 522         inode->i_uid = sbi->options.fs_uid;
 523         inode->i_gid = sbi->options.fs_gid;
 524         inode_inc_iversion(inode);
 525         inode->i_generation = prandom_u32();
 526
 527         if ((de->attr & ATTR_DIR) && !IS_FREE(de->name)) {
 528                 inode->i_generation &= ~1;
 529                 inode->i_mode = fat_make_mode(sbi, de->attr, S_IRWXUGO);
 530                 inode->i_op = sbi->dir_ops;
 531                 inode->i_fop = &fat_dir_operations;
 532
 533                 MSDOS_I(inode)->i_start = fat_get_start(sbi, de);
 534                 MSDOS_I(inode)->i_logstart = MSDOS_I(inode)->i_start;
 535                 error = fat_calc_dir_size(inode);
 536                 if (error < 0)
 537                         return error;
 538                 MSDOS_I(inode)->mmu_private = inode->i_size;
 539
 540                 set_nlink(inode, fat_subdirs(inode));
 541
 542                 error = fat_validate_dir(inode);
 543                 if (error < 0)
 544                         return error;
 545         } else { /* not a directory */
 546                 inode->i_generation |= 1;
 547                 inode->i_mode = fat_make_mode(sbi, de->attr,
 548                         ((sbi->options.showexec && !is_exec(de->name + 8))
 549                          ? S_IRUGO|S_IWUGO : S_IRWXUGO));
 550                 MSDOS_I(inode)->i_start = fat_get_start(sbi, de);
 551
 552                 MSDOS_I(inode)->i_logstart = MSDOS_I(inode)->i_start;
 553                 inode->i_size = le32_to_cpu(de->size);
 554                 inode->i_op = &fat_file_inode_operations;
 555                 inode->i_fop = &fat_file_operations;
 556                 inode->i_mapping->a_ops = &fat_aops;
 557                 MSDOS_I(inode)->mmu_private = inode->i_size;
 558         }
 559         if (de->attr & ATTR_SYS) {
 560                 if (sbi->options.sys_immutable)
 561                         inode->i_flags |= S_IMMUTABLE;
 562         }
 563         fat_save_attrs(inode, de->attr);
 564
 565         inode->i_blocks = ((inode->i_size + (sbi->cluster_size - 1))
 566                            & ~((loff_t)sbi->cluster_size - 1)) >> 9;
 567
 568         fat_time_fat2unix(sbi, &inode->i_mtime, de->time, de->date, 0);
 569         if (sbi->options.isvfat) {
 570                 fat_time_fat2unix(sbi, &inode->i_ctime, de->ctime,
 571                                   de->cdate, de->ctime_cs);
 572                 fat_time_fat2unix(sbi, &inode->i_atime, 0, de->adate, 0);
 573         } else
 574                 fat_truncate_time(inode, &inode->i_mtime, S_ATIME|S_CTIME);
 575
 576         return 0;
 577 }
 578
 579 static inline void fat_lock_build_inode(struct msdos_sb_info *sbi)
 580 {
 581         if (sbi->options.nfs == FAT_NFS_NOSTALE_RO)
 582                 mutex_lock(&sbi->nfs_build_inode_lock);
 583 }
 584
 585 static inline void fat_unlock_build_inode(struct msdos_sb_info *sbi)
 586 {
 587         if (sbi->options.nfs == FAT_NFS_NOSTALE_RO)
 588                 mutex_unlock(&sbi->nfs_build_inode_lock);
 589 }
 590
 591 struct inode *fat_build_inode(struct super_block *sb,
 592                         struct msdos_dir_entry *de, loff_t i_pos)
 593 {
 594         struct inode *inode;
 595         int err;
 596
 597         fat_lock_build_inode(MSDOS_SB(sb));
 598         inode = fat_iget(sb, i_pos);
 599         if (inode)
 600                 goto out;
 601         inode = new_inode(sb);
 602         if (!inode) {
 603                 inode = ERR_PTR(-ENOMEM);
 604                 goto out;
 605         }
 606         inode->i_ino = iunique(sb, MSDOS_ROOT_INO);
 607         inode_set_iversion(inode, 1);
 608         err = fat_fill_inode(inode, de);
 609         if (err) {
 610                 iput(inode);
 611                 inode = ERR_PTR(err);
 612                 goto out;
 613         }
 614         fat_attach(inode, i_pos);
 615         insert_inode_hash(inode);
 616 out:
 617         fat_unlock_build_inode(MSDOS_SB(sb));
 618         return inode;
 619 }
 620
 621 EXPORT_SYMBOL_GPL(fat_build_inode);
 622
 623 static int __fat_write_inode(struct inode *inode, int wait);
 624
 625 static void fat_free_eofblocks(struct inode *inode)
 626 {
 627         /* Release unwritten fallocated blocks on inode eviction. */
 628         if ((inode->i_blocks << 9) >
 629                         round_up(MSDOS_I(inode)->mmu_private,
 630                                 MSDOS_SB(inode->i_sb)->cluster_size)) {
 631                 int err;
 632
 633                 fat_truncate_blocks(inode, MSDOS_I(inode)->mmu_private);
 634                 /* Fallocate results in updating the i_start/iogstart
 635                  * for the zero byte file. So, make it return to
 636                  * original state during evict and commit it to avoid
 637                  * any corruption on the next access to the cluster
 638                  * chain for the file.
 639                  */
 640                 err = __fat_write_inode(inode, inode_needs_sync(inode));
 641                 if (err) {
 642                         fat_msg(inode->i_sb, KERN_WARNING, "Failed to "
 643                                         "update on disk inode for unused "
 644                                         "fallocated blocks, inode could be "
 645                                         "corrupted. Please run fsck");
 646                 }
 647
 648         }
 649 }
 650
 651 static void fat_evict_inode(struct inode *inode)
 652 {
 653         truncate_inode_pages_final(&inode->i_data);
 654         if (!inode->i_nlink) {
 655                 inode->i_size = 0;
 656                 fat_truncate_blocks(inode, 0);
 657         } else
 658                 fat_free_eofblocks(inode);
 659
 660         invalidate_inode_buffers(inode);
 661         clear_inode(inode);
 662         fat_cache_inval_inode(inode);
 663         fat_detach(inode);
 664 }
 665
 666 static void fat_set_state(struct super_block *sb,
 667                         unsigned int set, unsigned int force)
 668 {
 669         struct buffer_head *bh;
 670         struct fat_boot_sector *b;
 671         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 672
 673         /* do not change any thing if mounted read only */
 674         if (sb_rdonly(sb) && !force)
 675                 return;
 676
 677         /* do not change state if fs was dirty */
 678         if (sbi->dirty) {
 679                 /* warn only on set (mount). */
 680                 if (set)
 681                         fat_msg(sb, KERN_WARNING, "Volume was not properly "
 682                                 "unmounted. Some data may be corrupt. "
 683                                 "Please run fsck.");
 684                 return;
 685         }
 686
 687         bh = sb_bread(sb, 0);
 688         if (bh == NULL) {
 689                 fat_msg(sb, KERN_ERR, "unable to read boot sector "
 690                         "to mark fs as dirty");
 691                 return;
 692         }
 693
 694         b = (struct fat_boot_sector *) bh->b_data;
 695
 696         if (is_fat32(sbi)) {
 697                 if (set)
 698                         b->fat32.state |= FAT_STATE_DIRTY;
 699                 else
 700                         b->fat32.state &= ~FAT_STATE_DIRTY;
 701         } else /* fat 16 and 12 */ {
 702                 if (set)
 703                         b->fat16.state |= FAT_STATE_DIRTY;
 704                 else
 705                         b->fat16.state &= ~FAT_STATE_DIRTY;
 706         }
 707
 708         mark_buffer_dirty(bh);
 709         sync_dirty_buffer(bh);
 710         brelse(bh);
 711 }
 712
 713 static void fat_reset_iocharset(struct fat_mount_options *opts)
 714 {
 715         if (opts->iocharset != fat_default_iocharset) {
 716                 /* Note: opts->iocharset can be NULL here */
 717                 kfree(opts->iocharset);
 718                 opts->iocharset = fat_default_iocharset;
 719         }
 720 }
 721
 722 static void delayed_free(struct rcu_head *p)
 723 {
 724         struct msdos_sb_info *sbi = container_of(p, struct msdos_sb_info, rcu);
 725         unload_nls(sbi->nls_disk);
 726         unload_nls(sbi->nls_io);
 727         fat_reset_iocharset(&sbi->options);
 728         kfree(sbi);
 729 }
 730
 731 static void fat_put_super(struct super_block *sb)
 732 {
 733         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 734
 735         fat_set_state(sb, 0, 0);
 736
 737         iput(sbi->fsinfo_inode);
 738         iput(sbi->fat_inode);
 739
 740         call_rcu(&sbi->rcu, delayed_free);
 741 }
 742
 743 static struct kmem_cache *fat_inode_cachep;
 744
 745 static struct inode *fat_alloc_inode(struct super_block *sb)
 746 {
 747         struct msdos_inode_info *ei;
 748         ei = kmem_cache_alloc(fat_inode_cachep, GFP_NOFS);
 749         if (!ei)
 750                 return NULL;
 751
 752         init_rwsem(&ei->truncate_lock);
 753         /* Zeroing to allow iput() even if partial initialized inode. */
 754         ei->mmu_private = 0;
 755         ei->i_start = 0;
 756         ei->i_logstart = 0;
 757         ei->i_attrs = 0;
 758         ei->i_pos = 0;
 759
 760         return &ei->vfs_inode;
 761 }
 762
 763 static void fat_free_inode(struct inode *inode)
 764 {
 765         kmem_cache_free(fat_inode_cachep, MSDOS_I(inode));
 766 }
 767
 768 static void init_once(void *foo)
 769 {
 770         struct msdos_inode_info *ei = (struct msdos_inode_info *)foo;
 771
 772         spin_lock_init(&ei->cache_lru_lock);
 773         ei->nr_caches = 0;
 774         ei->cache_valid_id = FAT_CACHE_VALID + 1;
 775         INIT_LIST_HEAD(&ei->cache_lru);
 776         INIT_HLIST_NODE(&ei->i_fat_hash);
 777         INIT_HLIST_NODE(&ei->i_dir_hash);
 778         inode_init_once(&ei->vfs_inode);
 779 }
 780
 781 static int __init fat_init_inodecache(void)
 782 {
 783         fat_inode_cachep = kmem_cache_create("fat_inode_cache",
 784                                              sizeof(struct msdos_inode_info),
 785                                              0, (SLAB_RECLAIM_ACCOUNT|
 786                                                 SLAB_MEM_SPREAD|SLAB_ACCOUNT),
 787                                              init_once);
 788         if (fat_inode_cachep == NULL)
 789                 return -ENOMEM;
 790         return 0;
 791 }
 792
 793 static void __exit fat_destroy_inodecache(void)
 794 {
 795         /*
 796          * Make sure all delayed rcu free inodes are flushed before we
 797          * destroy cache.
 798          */
 799         rcu_barrier();
 800         kmem_cache_destroy(fat_inode_cachep);
 801 }
 802
 803 static int fat_remount(struct super_block *sb, int *flags, char *data)
 804 {
 805         bool new_rdonly;
 806         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 807         *flags |= SB_NODIRATIME | (sbi->options.isvfat ? 0 : SB_NOATIME);
 808
 809         sync_filesystem(sb);
 810
 811         /* make sure we update state on remount. */
 812         new_rdonly = *flags & SB_RDONLY;
 813         if (new_rdonly != sb_rdonly(sb)) {
 814                 if (new_rdonly)
 815                         fat_set_state(sb, 0, 0);
 816                 else
 817                         fat_set_state(sb, 1, 1);
 818         }
 819         return 0;
 820 }
 821
 822 static int fat_statfs(struct dentry *dentry, struct kstatfs *buf)
 823 {
 824         struct super_block *sb = dentry->d_sb;
 825         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 826         u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
 827
 828         /* If the count of free cluster is still unknown, counts it here. */
 829         if (sbi->free_clusters == -1 || !sbi->free_clus_valid) {
 830                 int err = fat_count_free_clusters(dentry->d_sb);
 831                 if (err)
 832                         return err;
 833         }
 834
 835         buf->f_type = dentry->d_sb->s_magic;
 836         buf->f_bsize = sbi->cluster_size;
 837         buf->f_blocks = sbi->max_cluster - FAT_START_ENT;
 838         buf->f_bfree = sbi->free_clusters;
 839         buf->f_bavail = sbi->free_clusters;
 840         buf->f_fsid.val[0] = (u32)id;
 841         buf->f_fsid.val[1] = (u32)(id >> 32);
 842         buf->f_namelen =
 843                 (sbi->options.isvfat ? FAT_LFN_LEN : 12) * NLS_MAX_CHARSET_SIZE;
 844
 845         return 0;
 846 }
 847
 848 static int __fat_write_inode(struct inode *inode, int wait)
 849 {
 850         struct super_block *sb = inode->i_sb;
 851         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 852         struct buffer_head *bh;
 853         struct msdos_dir_entry *raw_entry;
 854         loff_t i_pos;
 855         sector_t blocknr;
 856         int err, offset;
 857
 858         if (inode->i_ino == MSDOS_ROOT_INO)
 859                 return 0;
 860
 861 retry:
 862         i_pos = fat_i_pos_read(sbi, inode);
 863         if (!i_pos)
 864                 return 0;
 865
 866         fat_get_blknr_offset(sbi, i_pos, &blocknr, &offset);
 867         bh = sb_bread(sb, blocknr);
 868         if (!bh) {
 869                 fat_msg(sb, KERN_ERR, "unable to read inode block "
 870                        "for updating (i_pos %lld)", i_pos);
 871                 return -EIO;
 872         }
 873         spin_lock(&sbi->inode_hash_lock);
 874         if (i_pos != MSDOS_I(inode)->i_pos) {
 875                 spin_unlock(&sbi->inode_hash_lock);
 876                 brelse(bh);
 877                 goto retry;
 878         }
 879
 880         raw_entry = &((struct msdos_dir_entry *) (bh->b_data))[offset];
 881         if (S_ISDIR(inode->i_mode))
 882                 raw_entry->size = 0;
 883         else
 884                 raw_entry->size = cpu_to_le32(inode->i_size);
 885         raw_entry->attr = fat_make_attrs(inode);
 886         fat_set_start(raw_entry, MSDOS_I(inode)->i_logstart);
 887         fat_time_unix2fat(sbi, &inode->i_mtime, &raw_entry->time,
 888                           &raw_entry->date, NULL);
 889         if (sbi->options.isvfat) {
 890                 __le16 atime;
 891                 fat_time_unix2fat(sbi, &inode->i_ctime, &raw_entry->ctime,
 892                                   &raw_entry->cdate, &raw_entry->ctime_cs);
 893                 fat_time_unix2fat(sbi, &inode->i_atime, &atime,
 894                                   &raw_entry->adate, NULL);
 895         }
 896         spin_unlock(&sbi->inode_hash_lock);
 897         mark_buffer_dirty(bh);
 898         err = 0;
 899         if (wait)
 900                 err = sync_dirty_buffer(bh);
 901         brelse(bh);
 902         return err;
 903 }
 904
 905 static int fat_write_inode(struct inode *inode, struct writeback_control *wbc)
 906 {
 907         int err;
 908
 909         if (inode->i_ino == MSDOS_FSINFO_INO) {
 910                 struct super_block *sb = inode->i_sb;
 911
 912                 mutex_lock(&MSDOS_SB(sb)->s_lock);
 913                 err = fat_clusters_flush(sb);
 914                 mutex_unlock(&MSDOS_SB(sb)->s_lock);
 915         } else
 916                 err = __fat_write_inode(inode, wbc->sync_mode == WB_SYNC_ALL);
 917
 918         return err;
 919 }
 920
 921 int fat_sync_inode(struct inode *inode)
 922 {
 923         return __fat_write_inode(inode, 1);
 924 }
 925
 926 EXPORT_SYMBOL_GPL(fat_sync_inode);
 927
 928 static int fat_show_options(struct seq_file *m, struct dentry *root);
 929 static const struct super_operations fat_sops = {
 930         .alloc_inode    = fat_alloc_inode,
 931         .free_inode     = fat_free_inode,
 932         .write_inode    = fat_write_inode,
 933         .evict_inode    = fat_evict_inode,
 934         .put_super      = fat_put_super,
 935         .statfs         = fat_statfs,
 936         .remount_fs     = fat_remount,
 937
 938         .show_options   = fat_show_options,
 939 };
 940
 941 static int fat_show_options(struct seq_file *m, struct dentry *root)
 942 {
 943         struct msdos_sb_info *sbi = MSDOS_SB(root->d_sb);
 944         struct fat_mount_options *opts = &sbi->options;
 945         int isvfat = opts->isvfat;
 946
 947         if (!uid_eq(opts->fs_uid, GLOBAL_ROOT_UID))
 948                 seq_printf(m, ",uid=%u",
 949                                 from_kuid_munged(&init_user_ns, opts->fs_uid));
 950         if (!gid_eq(opts->fs_gid, GLOBAL_ROOT_GID))
 951                 seq_printf(m, ",gid=%u",
 952                                 from_kgid_munged(&init_user_ns, opts->fs_gid));
 953         seq_printf(m, ",fmask=%04o", opts->fs_fmask);
 954         seq_printf(m, ",dmask=%04o", opts->fs_dmask);
 955         if (opts->allow_utime)
 956                 seq_printf(m, ",allow_utime=%04o", opts->allow_utime);
 957         if (sbi->nls_disk)
 958                 /* strip "cp" prefix from displayed option */
 959                 seq_printf(m, ",codepage=%s", &sbi->nls_disk->charset[2]);
 960         if (isvfat) {
 961                 if (sbi->nls_io)
 962                         seq_printf(m, ",iocharset=%s", sbi->nls_io->charset);
 963
 964                 switch (opts->shortname) {
 965                 case VFAT_SFN_DISPLAY_WIN95 | VFAT_SFN_CREATE_WIN95:
 966                         seq_puts(m, ",shortname=win95");
 967                         break;
 968                 case VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WINNT:
 969                         seq_puts(m, ",shortname=winnt");
 970                         break;
 971                 case VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WIN95:
 972                         seq_puts(m, ",shortname=mixed");
 973                         break;
 974                 case VFAT_SFN_DISPLAY_LOWER | VFAT_SFN_CREATE_WIN95:
 975                         seq_puts(m, ",shortname=lower");
 976                         break;
 977                 default:
 978                         seq_puts(m, ",shortname=unknown");
 979                         break;
 980                 }
 981         }
 982         if (opts->name_check != 'n')
 983                 seq_printf(m, ",check=%c", opts->name_check);
 984         if (opts->usefree)
 985                 seq_puts(m, ",usefree");
 986         if (opts->quiet)
 987                 seq_puts(m, ",quiet");
 988         if (opts->showexec)
 989                 seq_puts(m, ",showexec");
 990         if (opts->sys_immutable)
 991                 seq_puts(m, ",sys_immutable");
 992         if (!isvfat) {
 993                 if (opts->dotsOK)
 994                         seq_puts(m, ",dotsOK=yes");
 995                 if (opts->nocase)
 996                         seq_puts(m, ",nocase");
 997         } else {
 998                 if (opts->utf8)
 999                         seq_puts(m, ",utf8");
1000                 if (opts->unicode_xlate)
1001                         seq_puts(m, ",uni_xlate");
1002                 if (!opts->numtail)
1003                         seq_puts(m, ",nonumtail");
1004                 if (opts->rodir)
1005                         seq_puts(m, ",rodir");
1006         }
1007         if (opts->flush)
1008                 seq_puts(m, ",flush");
1009         if (opts->tz_set) {
1010                 if (opts->time_offset)
1011                         seq_printf(m, ",time_offset=%d", opts->time_offset);
1012                 else
1013                         seq_puts(m, ",tz=UTC");
1014         }
1015         if (opts->errors == FAT_ERRORS_CONT)
1016                 seq_puts(m, ",errors=continue");
1017         else if (opts->errors == FAT_ERRORS_PANIC)
1018                 seq_puts(m, ",errors=panic");
1019         else
1020                 seq_puts(m, ",errors=remount-ro");
1021         if (opts->nfs == FAT_NFS_NOSTALE_RO)
1022                 seq_puts(m, ",nfs=nostale_ro");
1023         else if (opts->nfs)
1024                 seq_puts(m, ",nfs=stale_rw");
1025         if (opts->discard)
1026                 seq_puts(m, ",discard");
1027         if (opts->dos1xfloppy)
1028                 seq_puts(m, ",dos1xfloppy");
1029
1030         return 0;
1031 }
1032
1033 enum {
1034         Opt_check_n, Opt_check_r, Opt_check_s, Opt_uid, Opt_gid,
1035         Opt_umask, Opt_dmask, Opt_fmask, Opt_allow_utime, Opt_codepage,
1036         Opt_usefree, Opt_nocase, Opt_quiet, Opt_showexec, Opt_debug,
1037         Opt_immutable, Opt_dots, Opt_nodots,
1038         Opt_charset, Opt_shortname_lower, Opt_shortname_win95,
1039         Opt_shortname_winnt, Opt_shortname_mixed, Opt_utf8_no, Opt_utf8_yes,
1040         Opt_uni_xl_no, Opt_uni_xl_yes, Opt_nonumtail_no, Opt_nonumtail_yes,
1041         Opt_obsolete, Opt_flush, Opt_tz_utc, Opt_rodir, Opt_err_cont,
1042         Opt_err_panic, Opt_err_ro, Opt_discard, Opt_nfs, Opt_time_offset,
1043         Opt_nfs_stale_rw, Opt_nfs_nostale_ro, Opt_err, Opt_dos1xfloppy,
1044 };
1045
1046 static const match_table_t fat_tokens = {
1047         {Opt_check_r, "check=relaxed"},
1048         {Opt_check_s, "check=strict"},
1049         {Opt_check_n, "check=normal"},
1050         {Opt_check_r, "check=r"},
1051         {Opt_check_s, "check=s"},
1052         {Opt_check_n, "check=n"},
1053         {Opt_uid, "uid=%u"},
1054         {Opt_gid, "gid=%u"},
1055         {Opt_umask, "umask=%o"},
1056         {Opt_dmask, "dmask=%o"},
1057         {Opt_fmask, "fmask=%o"},
1058         {Opt_allow_utime, "allow_utime=%o"},
1059         {Opt_codepage, "codepage=%u"},
1060         {Opt_usefree, "usefree"},
1061         {Opt_nocase, "nocase"},
1062         {Opt_quiet, "quiet"},
1063         {Opt_showexec, "showexec"},
1064         {Opt_debug, "debug"},
1065         {Opt_immutable, "sys_immutable"},
1066         {Opt_flush, "flush"},
1067         {Opt_tz_utc, "tz=UTC"},
1068         {Opt_time_offset, "time_offset=%d"},
1069         {Opt_err_cont, "errors=continue"},
1070         {Opt_err_panic, "errors=panic"},
1071         {Opt_err_ro, "errors=remount-ro"},
1072         {Opt_discard, "discard"},
1073         {Opt_nfs_stale_rw, "nfs"},
1074         {Opt_nfs_stale_rw, "nfs=stale_rw"},
1075         {Opt_nfs_nostale_ro, "nfs=nostale_ro"},
1076         {Opt_dos1xfloppy, "dos1xfloppy"},
1077         {Opt_obsolete, "conv=binary"},
1078         {Opt_obsolete, "conv=text"},
1079         {Opt_obsolete, "conv=auto"},
1080         {Opt_obsolete, "conv=b"},
1081         {Opt_obsolete, "conv=t"},
1082         {Opt_obsolete, "conv=a"},
1083         {Opt_obsolete, "fat=%u"},
1084         {Opt_obsolete, "blocksize=%u"},
1085         {Opt_obsolete, "cvf_format=%20s"},
1086         {Opt_obsolete, "cvf_options=%100s"},
1087         {Opt_obsolete, "posix"},
1088         {Opt_err, NULL},
1089 };
1090 static const match_table_t msdos_tokens = {
1091         {Opt_nodots, "nodots"},
1092         {Opt_nodots, "dotsOK=no"},
1093         {Opt_dots, "dots"},
1094         {Opt_dots, "dotsOK=yes"},
1095         {Opt_err, NULL}
1096 };
1097 static const match_table_t vfat_tokens = {
1098         {Opt_charset, "iocharset=%s"},
1099         {Opt_shortname_lower, "shortname=lower"},
1100         {Opt_shortname_win95, "shortname=win95"},
1101         {Opt_shortname_winnt, "shortname=winnt"},
1102         {Opt_shortname_mixed, "shortname=mixed"},
1103         {Opt_utf8_no, "utf8=0"},                /* 0 or no or false */
1104         {Opt_utf8_no, "utf8=no"},
1105         {Opt_utf8_no, "utf8=false"},
1106         {Opt_utf8_yes, "utf8=1"},               /* empty or 1 or yes or true */
1107         {Opt_utf8_yes, "utf8=yes"},
1108         {Opt_utf8_yes, "utf8=true"},
1109         {Opt_utf8_yes, "utf8"},
1110         {Opt_uni_xl_no, "uni_xlate=0"},         /* 0 or no or false */
1111         {Opt_uni_xl_no, "uni_xlate=no"},
1112         {Opt_uni_xl_no, "uni_xlate=false"},
1113         {Opt_uni_xl_yes, "uni_xlate=1"},        /* empty or 1 or yes or true */
1114         {Opt_uni_xl_yes, "uni_xlate=yes"},
1115         {Opt_uni_xl_yes, "uni_xlate=true"},
1116         {Opt_uni_xl_yes, "uni_xlate"},
1117         {Opt_nonumtail_no, "nonumtail=0"},      /* 0 or no or false */
1118         {Opt_nonumtail_no, "nonumtail=no"},
1119         {Opt_nonumtail_no, "nonumtail=false"},
1120         {Opt_nonumtail_yes, "nonumtail=1"},     /* empty or 1 or yes or true */
1121         {Opt_nonumtail_yes, "nonumtail=yes"},
1122         {Opt_nonumtail_yes, "nonumtail=true"},
1123         {Opt_nonumtail_yes, "nonumtail"},
1124         {Opt_rodir, "rodir"},
1125         {Opt_err, NULL}
1126 };
1127
1128 static int parse_options(struct super_block *sb, char *options, int is_vfat,
1129                          int silent, int *debug, struct fat_mount_options *opts)
1130 {
1131         char *p;
1132         substring_t args[MAX_OPT_ARGS];
1133         int option;
1134         char *iocharset;
1135
1136         opts->isvfat = is_vfat;
1137
1138         opts->fs_uid = current_uid();
1139         opts->fs_gid = current_gid();
1140         opts->fs_fmask = opts->fs_dmask = current_umask();
1141         opts->allow_utime = -1;
1142         opts->codepage = fat_default_codepage;
1143         fat_reset_iocharset(opts);
1144         if (is_vfat) {
1145                 opts->shortname = VFAT_SFN_DISPLAY_WINNT|VFAT_SFN_CREATE_WIN95;
1146                 opts->rodir = 0;
1147         } else {
1148                 opts->shortname = 0;
1149                 opts->rodir = 1;
1150         }
1151         opts->name_check = 'n';
1152         opts->quiet = opts->showexec = opts->sys_immutable = opts->dotsOK =  0;
1153         opts->unicode_xlate = 0;
1154         opts->numtail = 1;
1155         opts->usefree = opts->nocase = 0;
1156         opts->tz_set = 0;
1157         opts->nfs = 0;
1158         opts->errors = FAT_ERRORS_RO;
1159         *debug = 0;
1160
1161         opts->utf8 = IS_ENABLED(CONFIG_FAT_DEFAULT_UTF8) && is_vfat;
1162
1163         if (!options)
1164                 goto out;
1165
1166         while ((p = strsep(&options, ",")) != NULL) {
1167                 int token;
1168                 if (!*p)
1169                         continue;
1170
1171                 token = match_token(p, fat_tokens, args);
1172                 if (token == Opt_err) {
1173                         if (is_vfat)
1174                                 token = match_token(p, vfat_tokens, args);
1175                         else
1176                                 token = match_token(p, msdos_tokens, args);
1177                 }
1178                 switch (token) {
1179                 case Opt_check_s:
1180                         opts->name_check = 's';
1181                         break;
1182                 case Opt_check_r:
1183                         opts->name_check = 'r';
1184                         break;
1185                 case Opt_check_n:
1186                         opts->name_check = 'n';
1187                         break;
1188                 case Opt_usefree:
1189                         opts->usefree = 1;
1190                         break;
1191                 case Opt_nocase:
1192                         if (!is_vfat)
1193                                 opts->nocase = 1;
1194                         else {
1195                                 /* for backward compatibility */
1196                                 opts->shortname = VFAT_SFN_DISPLAY_WIN95
1197                                         | VFAT_SFN_CREATE_WIN95;
1198                         }
1199                         break;
1200                 case Opt_quiet:
1201                         opts->quiet = 1;
1202                         break;
1203                 case Opt_showexec:
1204                         opts->showexec = 1;
1205                         break;
1206                 case Opt_debug:
1207                         *debug = 1;
1208                         break;
1209                 case Opt_immutable:
1210                         opts->sys_immutable = 1;
1211                         break;
1212                 case Opt_uid:
1213                         if (match_int(&args[0], &option))
1214                                 return -EINVAL;
1215                         opts->fs_uid = make_kuid(current_user_ns(), option);
1216                         if (!uid_valid(opts->fs_uid))
1217                                 return -EINVAL;
1218                         break;
1219                 case Opt_gid:
1220                         if (match_int(&args[0], &option))
1221                                 return -EINVAL;
1222                         opts->fs_gid = make_kgid(current_user_ns(), option);
1223                         if (!gid_valid(opts->fs_gid))
1224                                 return -EINVAL;
1225                         break;
1226                 case Opt_umask:
1227                         if (match_octal(&args[0], &option))
1228                                 return -EINVAL;
1229                         opts->fs_fmask = opts->fs_dmask = option;
1230                         break;
1231                 case Opt_dmask:
1232                         if (match_octal(&args[0], &option))
1233                                 return -EINVAL;
1234                         opts->fs_dmask = option;
1235                         break;
1236                 case Opt_fmask:
1237                         if (match_octal(&args[0], &option))
1238                                 return -EINVAL;
1239                         opts->fs_fmask = option;
1240                         break;
1241                 case Opt_allow_utime:
1242                         if (match_octal(&args[0], &option))
1243                                 return -EINVAL;
1244                         opts->allow_utime = option & (S_IWGRP | S_IWOTH);
1245                         break;
1246                 case Opt_codepage:
1247                         if (match_int(&args[0], &option))
1248                                 return -EINVAL;
1249                         opts->codepage = option;
1250                         break;
1251                 case Opt_flush:
1252                         opts->flush = 1;
1253                         break;
1254                 case Opt_time_offset:
1255                         if (match_int(&args[0], &option))
1256                                 return -EINVAL;
1257                         /*
1258                          * GMT+-12 zones may have DST corrections so at least
1259                          * 13 hours difference is needed. Make the limit 24
1260                          * just in case someone invents something unusual.
1261                          */
1262                         if (option < -24 * 60 || option > 24 * 60)
1263                                 return -EINVAL;
1264                         opts->tz_set = 1;
1265                         opts->time_offset = option;
1266                         break;
1267                 case Opt_tz_utc:
1268                         opts->tz_set = 1;
1269                         opts->time_offset = 0;
1270                         break;
1271                 case Opt_err_cont:
1272                         opts->errors = FAT_ERRORS_CONT;
1273                         break;
1274                 case Opt_err_panic:
1275                         opts->errors = FAT_ERRORS_PANIC;
1276                         break;
1277                 case Opt_err_ro:
1278                         opts->errors = FAT_ERRORS_RO;
1279                         break;
1280                 case Opt_nfs_stale_rw:
1281                         opts->nfs = FAT_NFS_STALE_RW;
1282                         break;
1283                 case Opt_nfs_nostale_ro:
1284                         opts->nfs = FAT_NFS_NOSTALE_RO;
1285                         break;
1286                 case Opt_dos1xfloppy:
1287                         opts->dos1xfloppy = 1;
1288                         break;
1289
1290                 /* msdos specific */
1291                 case Opt_dots:
1292                         opts->dotsOK = 1;
1293                         break;
1294                 case Opt_nodots:
1295                         opts->dotsOK = 0;
1296                         break;
1297
1298                 /* vfat specific */
1299                 case Opt_charset:
1300                         fat_reset_iocharset(opts);
1301                         iocharset = match_strdup(&args[0]);
1302                         if (!iocharset)
1303                                 return -ENOMEM;
1304                         opts->iocharset = iocharset;
1305                         break;
1306                 case Opt_shortname_lower:
1307                         opts->shortname = VFAT_SFN_DISPLAY_LOWER
1308                                         | VFAT_SFN_CREATE_WIN95;
1309                         break;
1310                 case Opt_shortname_win95:
1311                         opts->shortname = VFAT_SFN_DISPLAY_WIN95
1312                                         | VFAT_SFN_CREATE_WIN95;
1313                         break;
1314                 case Opt_shortname_winnt:
1315                         opts->shortname = VFAT_SFN_DISPLAY_WINNT
1316                                         | VFAT_SFN_CREATE_WINNT;
1317                         break;
1318                 case Opt_shortname_mixed:
1319                         opts->shortname = VFAT_SFN_DISPLAY_WINNT
1320                                         | VFAT_SFN_CREATE_WIN95;
1321                         break;
1322                 case Opt_utf8_no:               /* 0 or no or false */
1323                         opts->utf8 = 0;
1324                         break;
1325                 case Opt_utf8_yes:              /* empty or 1 or yes or true */
1326                         opts->utf8 = 1;
1327                         break;
1328                 case Opt_uni_xl_no:             /* 0 or no or false */
1329                         opts->unicode_xlate = 0;
1330                         break;
1331                 case Opt_uni_xl_yes:            /* empty or 1 or yes or true */
1332                         opts->unicode_xlate = 1;
1333                         break;
1334                 case Opt_nonumtail_no:          /* 0 or no or false */
1335                         opts->numtail = 1;      /* negated option */
1336                         break;
1337                 case Opt_nonumtail_yes:         /* empty or 1 or yes or true */
1338                         opts->numtail = 0;      /* negated option */
1339                         break;
1340                 case Opt_rodir:
1341                         opts->rodir = 1;
1342                         break;
1343                 case Opt_discard:
1344                         opts->discard = 1;
1345                         break;
1346
1347                 /* obsolete mount options */
1348                 case Opt_obsolete:
1349                         fat_msg(sb, KERN_INFO, "\"%s\" option is obsolete, "
1350                                "not supported now", p);
1351                         break;
1352                 /* unknown option */
1353                 default:
1354                         if (!silent) {
1355                                 fat_msg(sb, KERN_ERR,
1356                                        "Unrecognized mount option \"%s\" "
1357                                        "or missing value", p);
1358                         }
1359                         return -EINVAL;
1360                 }
1361         }
1362
1363 out:
1364         /* UTF-8 doesn't provide FAT semantics */
1365         if (!strcmp(opts->iocharset, "utf8")) {
1366                 fat_msg(sb, KERN_WARNING, "utf8 is not a recommended IO charset"
1367                        " for FAT filesystems, filesystem will be "
1368                        "case sensitive!");
1369         }
1370
1371         /* If user doesn't specify allow_utime, it's initialized from dmask. */
1372         if (opts->allow_utime == (unsigned short)-1)
1373                 opts->allow_utime = ~opts->fs_dmask & (S_IWGRP | S_IWOTH);
1374         if (opts->unicode_xlate)
1375                 opts->utf8 = 0;
1376         if (opts->nfs == FAT_NFS_NOSTALE_RO) {
1377                 sb->s_flags |= SB_RDONLY;
1378                 sb->s_export_op = &fat_export_ops_nostale;
1379         }
1380
1381         return 0;
1382 }
1383
1384 static int fat_read_root(struct inode *inode)
1385 {
1386         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
1387         int error;
1388
1389         MSDOS_I(inode)->i_pos = MSDOS_ROOT_INO;
1390         inode->i_uid = sbi->options.fs_uid;
1391         inode->i_gid = sbi->options.fs_gid;
1392         inode_inc_iversion(inode);
1393         inode->i_generation = 0;
1394         inode->i_mode = fat_make_mode(sbi, ATTR_DIR, S_IRWXUGO);
1395         inode->i_op = sbi->dir_ops;
1396         inode->i_fop = &fat_dir_operations;
1397         if (is_fat32(sbi)) {
1398                 MSDOS_I(inode)->i_start = sbi->root_cluster;
1399                 error = fat_calc_dir_size(inode);
1400                 if (error < 0)
1401                         return error;
1402         } else {
1403                 MSDOS_I(inode)->i_start = 0;
1404                 inode->i_size = sbi->dir_entries * sizeof(struct msdos_dir_entry);
1405         }
1406         inode->i_blocks = ((inode->i_size + (sbi->cluster_size - 1))
1407                            & ~((loff_t)sbi->cluster_size - 1)) >> 9;
1408         MSDOS_I(inode)->i_logstart = 0;
1409         MSDOS_I(inode)->mmu_private = inode->i_size;
1410
1411         fat_save_attrs(inode, ATTR_DIR);
1412         inode->i_mtime.tv_sec = inode->i_atime.tv_sec = inode->i_ctime.tv_sec = 0;
1413         inode->i_mtime.tv_nsec = inode->i_atime.tv_nsec = inode->i_ctime.tv_nsec = 0;
1414         set_nlink(inode, fat_subdirs(inode)+2);
1415
1416         return 0;
1417 }
1418
1419 static unsigned long calc_fat_clusters(struct super_block *sb)
1420 {
1421         struct msdos_sb_info *sbi = MSDOS_SB(sb);
1422
1423         /* Divide first to avoid overflow */
1424         if (!is_fat12(sbi)) {
1425                 unsigned long ent_per_sec = sb->s_blocksize * 8 / sbi->fat_bits;
1426                 return ent_per_sec * sbi->fat_length;
1427         }
1428
1429         return sbi->fat_length * sb->s_blocksize * 8 / sbi->fat_bits;
1430 }
1431
1432 static bool fat_bpb_is_zero(struct fat_boot_sector *b)
1433 {
1434         if (get_unaligned_le16(&b->sector_size))
1435                 return false;
1436         if (b->sec_per_clus)
1437                 return false;
1438         if (b->reserved)
1439                 return false;
1440         if (b->fats)
1441                 return false;
1442         if (get_unaligned_le16(&b->dir_entries))
1443                 return false;
1444         if (get_unaligned_le16(&b->sectors))
1445                 return false;
1446         if (b->media)
1447                 return false;
1448         if (b->fat_length)
1449                 return false;
1450         if (b->secs_track)
1451                 return false;
1452         if (b->heads)
1453                 return false;
1454         return true;
1455 }
1456
1457 static int fat_read_bpb(struct super_block *sb, struct fat_boot_sector *b,
1458         int silent, struct fat_bios_param_block *bpb)
1459 {
1460         int error = -EINVAL;
1461
1462         /* Read in BPB ... */
1463         memset(bpb, 0, sizeof(*bpb));
1464         bpb->fat_sector_size = get_unaligned_le16(&b->sector_size);
1465         bpb->fat_sec_per_clus = b->sec_per_clus;
1466         bpb->fat_reserved = le16_to_cpu(b->reserved);
1467         bpb->fat_fats = b->fats;
1468         bpb->fat_dir_entries = get_unaligned_le16(&b->dir_entries);
1469         bpb->fat_sectors = get_unaligned_le16(&b->sectors);
1470         bpb->fat_fat_length = le16_to_cpu(b->fat_length);
1471         bpb->fat_total_sect = le32_to_cpu(b->total_sect);
1472
1473         bpb->fat16_state = b->fat16.state;
1474         bpb->fat16_vol_id = get_unaligned_le32(b->fat16.vol_id);
1475
1476         bpb->fat32_length = le32_to_cpu(b->fat32.length);
1477         bpb->fat32_root_cluster = le32_to_cpu(b->fat32.root_cluster);
1478         bpb->fat32_info_sector = le16_to_cpu(b->fat32.info_sector);
1479         bpb->fat32_state = b->fat32.state;
1480         bpb->fat32_vol_id = get_unaligned_le32(b->fat32.vol_id);
1481
1482         /* Validate this looks like a FAT filesystem BPB */
1483         if (!bpb->fat_reserved) {
1484                 if (!silent)
1485                         fat_msg(sb, KERN_ERR,
1486                                 "bogus number of reserved sectors");
1487                 goto out;
1488         }
1489         if (!bpb->fat_fats) {
1490                 if (!silent)
1491                         fat_msg(sb, KERN_ERR, "bogus number of FAT structure");
1492                 goto out;
1493         }
1494
1495         /*
1496          * Earlier we checked here that b->secs_track and b->head are nonzero,
1497          * but it turns out valid FAT filesystems can have zero there.
1498          */
1499
1500         if (!fat_valid_media(b->media)) {
1501                 if (!silent)
1502                         fat_msg(sb, KERN_ERR, "invalid media value (0x%02x)",
1503                                 (unsigned)b->media);
1504                 goto out;
1505         }
1506
1507         if (!is_power_of_2(bpb->fat_sector_size)
1508             || (bpb->fat_sector_size < 512)
1509             || (bpb->fat_sector_size > 4096)) {
1510                 if (!silent)
1511                         fat_msg(sb, KERN_ERR, "bogus logical sector size %u",
1512                                (unsigned)bpb->fat_sector_size);
1513                 goto out;
1514         }
1515
1516         if (!is_power_of_2(bpb->fat_sec_per_clus)) {
1517                 if (!silent)
1518                         fat_msg(sb, KERN_ERR, "bogus sectors per cluster %u",
1519                                 (unsigned)bpb->fat_sec_per_clus);
1520                 goto out;
1521         }
1522
1523         error = 0;
1524
1525 out:
1526         return error;
1527 }
1528
1529 static int fat_read_static_bpb(struct super_block *sb,
1530         struct fat_boot_sector *b, int silent,
1531         struct fat_bios_param_block *bpb)
1532 {
1533         static const char *notdos1x = "This doesn't look like a DOS 1.x volume";
1534
1535         struct fat_floppy_defaults *fdefaults = NULL;
1536         int error = -EINVAL;
1537         sector_t bd_sects;
1538         unsigned i;
1539
1540         bd_sects = i_size_read(sb->s_bdev->bd_inode) / SECTOR_SIZE;
1541
1542         /* 16-bit DOS 1.x reliably wrote bootstrap short-jmp code */
1543         if (b->ignored[0] != 0xeb || b->ignored[2] != 0x90) {
1544                 if (!silent)
1545                         fat_msg(sb, KERN_ERR,
1546                                 "%s; no bootstrapping code", notdos1x);
1547                 goto out;
1548         }
1549
1550         /*
1551          * If any value in this region is non-zero, it isn't archaic
1552          * DOS.
1553          */
1554         if (!fat_bpb_is_zero(b)) {
1555                 if (!silent)
1556                         fat_msg(sb, KERN_ERR,
1557                                 "%s; DOS 2.x BPB is non-zero", notdos1x);
1558                 goto out;
1559         }
1560
1561         for (i = 0; i < ARRAY_SIZE(floppy_defaults); i++) {
1562                 if (floppy_defaults[i].nr_sectors == bd_sects) {
1563                         fdefaults = &floppy_defaults[i];
1564                         break;
1565                 }
1566         }
1567
1568         if (fdefaults == NULL) {
1569                 if (!silent)
1570                         fat_msg(sb, KERN_WARNING,
1571                                 "This looks like a DOS 1.x volume, but isn't a recognized floppy size (%llu sectors)",
1572                                 (u64)bd_sects);
1573                 goto out;
1574         }
1575
1576         if (!silent)
1577                 fat_msg(sb, KERN_INFO,
1578                         "This looks like a DOS 1.x volume; assuming default BPB values");
1579
1580         memset(bpb, 0, sizeof(*bpb));
1581         bpb->fat_sector_size = SECTOR_SIZE;
1582         bpb->fat_sec_per_clus = fdefaults->sec_per_clus;
1583         bpb->fat_reserved = 1;
1584         bpb->fat_fats = 2;
1585         bpb->fat_dir_entries = fdefaults->dir_entries;
1586         bpb->fat_sectors = fdefaults->nr_sectors;
1587         bpb->fat_fat_length = fdefaults->fat_length;
1588
1589         error = 0;
1590
1591 out:
1592         return error;
1593 }
1594
1595 /*
1596  * Read the super block of an MS-DOS FS.
1597  */
1598 int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat,
1599                    void (*setup)(struct super_block *))
1600 {
1601         struct inode *root_inode = NULL, *fat_inode = NULL;
1602         struct inode *fsinfo_inode = NULL;
1603         struct buffer_head *bh;
1604         struct fat_bios_param_block bpb;
1605         struct msdos_sb_info *sbi;
1606         u16 logical_sector_size;
1607         u32 total_sectors, total_clusters, fat_clusters, rootdir_sectors;
1608         int debug;
1609         long error;
1610         char buf[50];
1611         struct timespec64 ts;
1612
1613         /*
1614          * GFP_KERNEL is ok here, because while we do hold the
1615          * superblock lock, memory pressure can't call back into
1616          * the filesystem, since we're only just about to mount
1617          * it and have no inodes etc active!
1618          */
1619         sbi = kzalloc(sizeof(struct msdos_sb_info), GFP_KERNEL);
1620         if (!sbi)
1621                 return -ENOMEM;
1622         sb->s_fs_info = sbi;
1623
1624         sb->s_flags |= SB_NODIRATIME;
1625         sb->s_magic = MSDOS_SUPER_MAGIC;
1626         sb->s_op = &fat_sops;
1627         sb->s_export_op = &fat_export_ops;
1628         /*
1629          * fat timestamps are complex and truncated by fat itself, so
1630          * we set 1 here to be fast
1631          */
1632         sb->s_time_gran = 1;
1633         mutex_init(&sbi->nfs_build_inode_lock);
1634         ratelimit_state_init(&sbi->ratelimit, DEFAULT_RATELIMIT_INTERVAL,
1635                              DEFAULT_RATELIMIT_BURST);
1636
1637         error = parse_options(sb, data, isvfat, silent, &debug, &sbi->options);
1638         if (error)
1639                 goto out_fail;
1640
1641         setup(sb); /* flavour-specific stuff that needs options */
1642
1643         error = -EIO;
1644         sb_min_blocksize(sb, 512);
1645         bh = sb_bread(sb, 0);
1646         if (bh == NULL) {
1647                 fat_msg(sb, KERN_ERR, "unable to read boot sector");
1648                 goto out_fail;
1649         }
1650
1651         error = fat_read_bpb(sb, (struct fat_boot_sector *)bh->b_data, silent,
1652                 &bpb);
1653         if (error == -EINVAL && sbi->options.dos1xfloppy)
1654                 error = fat_read_static_bpb(sb,
1655                         (struct fat_boot_sector *)bh->b_data, silent, &bpb);
1656         brelse(bh);
1657
1658         if (error == -EINVAL)
1659                 goto out_invalid;
1660         else if (error)
1661                 goto out_fail;
1662
1663         logical_sector_size = bpb.fat_sector_size;
1664         sbi->sec_per_clus = bpb.fat_sec_per_clus;
1665
1666         error = -EIO;
1667         if (logical_sector_size < sb->s_blocksize) {
1668                 fat_msg(sb, KERN_ERR, "logical sector size too small for device"
1669                        " (logical sector size = %u)", logical_sector_size);
1670                 goto out_fail;
1671         }
1672
1673         if (logical_sector_size > sb->s_blocksize) {
1674                 struct buffer_head *bh_resize;
1675
1676                 if (!sb_set_blocksize(sb, logical_sector_size)) {
1677                         fat_msg(sb, KERN_ERR, "unable to set blocksize %u",
1678                                logical_sector_size);
1679                         goto out_fail;
1680                 }
1681
1682                 /* Verify that the larger boot sector is fully readable */
1683                 bh_resize = sb_bread(sb, 0);
1684                 if (bh_resize == NULL) {
1685                         fat_msg(sb, KERN_ERR, "unable to read boot sector"
1686                                " (logical sector size = %lu)",
1687                                sb->s_blocksize);
1688                         goto out_fail;
1689                 }
1690                 brelse(bh_resize);
1691         }
1692
1693         mutex_init(&sbi->s_lock);
1694         sbi->cluster_size = sb->s_blocksize * sbi->sec_per_clus;
1695         sbi->cluster_bits = ffs(sbi->cluster_size) - 1;
1696         sbi->fats = bpb.fat_fats;
1697         sbi->fat_bits = 0;              /* Don't know yet */
1698         sbi->fat_start = bpb.fat_reserved;
1699         sbi->fat_length = bpb.fat_fat_length;
1700         sbi->root_cluster = 0;
1701         sbi->free_clusters = -1;        /* Don't know yet */
1702         sbi->free_clus_valid = 0;
1703         sbi->prev_free = FAT_START_ENT;
1704         sb->s_maxbytes = 0xffffffff;
1705         fat_time_fat2unix(sbi, &ts, 0, cpu_to_le16(FAT_DATE_MIN), 0);
1706         sb->s_time_min = ts.tv_sec;
1707
1708         fat_time_fat2unix(sbi, &ts, cpu_to_le16(FAT_TIME_MAX),
1709                           cpu_to_le16(FAT_DATE_MAX), 0);
1710         sb->s_time_max = ts.tv_sec;
1711
1712         if (!sbi->fat_length && bpb.fat32_length) {
1713                 struct fat_boot_fsinfo *fsinfo;
1714                 struct buffer_head *fsinfo_bh;
1715
1716                 /* Must be FAT32 */
1717                 sbi->fat_bits = 32;
1718                 sbi->fat_length = bpb.fat32_length;
1719                 sbi->root_cluster = bpb.fat32_root_cluster;
1720
1721                 /* MC - if info_sector is 0, don't multiply by 0 */
1722                 sbi->fsinfo_sector = bpb.fat32_info_sector;
1723                 if (sbi->fsinfo_sector == 0)
1724                         sbi->fsinfo_sector = 1;
1725
1726                 fsinfo_bh = sb_bread(sb, sbi->fsinfo_sector);
1727                 if (fsinfo_bh == NULL) {
1728                         fat_msg(sb, KERN_ERR, "bread failed, FSINFO block"
1729                                " (sector = %lu)", sbi->fsinfo_sector);
1730                         goto out_fail;
1731                 }
1732
1733                 fsinfo = (struct fat_boot_fsinfo *)fsinfo_bh->b_data;
1734                 if (!IS_FSINFO(fsinfo)) {
1735                         fat_msg(sb, KERN_WARNING, "Invalid FSINFO signature: "
1736                                "0x%08x, 0x%08x (sector = %lu)",
1737                                le32_to_cpu(fsinfo->signature1),
1738                                le32_to_cpu(fsinfo->signature2),
1739                                sbi->fsinfo_sector);
1740                 } else {
1741                         if (sbi->options.usefree)
1742                                 sbi->free_clus_valid = 1;
1743                         sbi->free_clusters = le32_to_cpu(fsinfo->free_clusters);
1744                         sbi->prev_free = le32_to_cpu(fsinfo->next_cluster);
1745                 }
1746
1747                 brelse(fsinfo_bh);
1748         }
1749
1750         /* interpret volume ID as a little endian 32 bit integer */
1751         if (is_fat32(sbi))
1752                 sbi->vol_id = bpb.fat32_vol_id;
1753         else /* fat 16 or 12 */
1754                 sbi->vol_id = bpb.fat16_vol_id;
1755
1756         sbi->dir_per_block = sb->s_blocksize / sizeof(struct msdos_dir_entry);
1757         sbi->dir_per_block_bits = ffs(sbi->dir_per_block) - 1;
1758
1759         sbi->dir_start = sbi->fat_start + sbi->fats * sbi->fat_length;
1760         sbi->dir_entries = bpb.fat_dir_entries;
1761         if (sbi->dir_entries & (sbi->dir_per_block - 1)) {
1762                 if (!silent)
1763                         fat_msg(sb, KERN_ERR, "bogus number of directory entries"
1764                                " (%u)", sbi->dir_entries);
1765                 goto out_invalid;
1766         }
1767
1768         rootdir_sectors = sbi->dir_entries
1769                 * sizeof(struct msdos_dir_entry) / sb->s_blocksize;
1770         sbi->data_start = sbi->dir_start + rootdir_sectors;
1771         total_sectors = bpb.fat_sectors;
1772         if (total_sectors == 0)
1773                 total_sectors = bpb.fat_total_sect;
1774
1775         total_clusters = (total_sectors - sbi->data_start) / sbi->sec_per_clus;
1776
1777         if (!is_fat32(sbi))
1778                 sbi->fat_bits = (total_clusters > MAX_FAT12) ? 16 : 12;
1779
1780         /* some OSes set FAT_STATE_DIRTY and clean it on unmount. */
1781         if (is_fat32(sbi))
1782                 sbi->dirty = bpb.fat32_state & FAT_STATE_DIRTY;
1783         else /* fat 16 or 12 */
1784                 sbi->dirty = bpb.fat16_state & FAT_STATE_DIRTY;
1785
1786         /* check that FAT table does not overflow */
1787         fat_clusters = calc_fat_clusters(sb);
1788         total_clusters = min(total_clusters, fat_clusters - FAT_START_ENT);
1789         if (total_clusters > max_fat(sb)) {
1790                 if (!silent)
1791                         fat_msg(sb, KERN_ERR, "count of clusters too big (%u)",
1792                                total_clusters);
1793                 goto out_invalid;
1794         }
1795
1796         sbi->max_cluster = total_clusters + FAT_START_ENT;
1797         /* check the free_clusters, it's not necessarily correct */
1798         if (sbi->free_clusters != -1 && sbi->free_clusters > total_clusters)
1799                 sbi->free_clusters = -1;
1800         /* check the prev_free, it's not necessarily correct */
1801         sbi->prev_free %= sbi->max_cluster;
1802         if (sbi->prev_free < FAT_START_ENT)
1803                 sbi->prev_free = FAT_START_ENT;
1804
1805         /* set up enough so that it can read an inode */
1806         fat_hash_init(sb);
1807         dir_hash_init(sb);
1808         fat_ent_access_init(sb);
1809
1810         /*
1811          * The low byte of the first FAT entry must have the same value as
1812          * the media field of the boot sector. But in real world, too many
1813          * devices are writing wrong values. So, removed that validity check.
1814          *
1815          * The removed check compared the first FAT entry to a value dependent
1816          * on the media field like this:
1817          * == (0x0F00 | media), for FAT12
1818          * == (0XFF00 | media), for FAT16
1819          * == (0x0FFFFF | media), for FAT32
1820          */
1821
1822         error = -EINVAL;
1823         sprintf(buf, "cp%d", sbi->options.codepage);
1824         sbi->nls_disk = load_nls(buf);
1825         if (!sbi->nls_disk) {
1826                 fat_msg(sb, KERN_ERR, "codepage %s not found", buf);
1827                 goto out_fail;
1828         }
1829
1830         /* FIXME: utf8 is using iocharset for upper/lower conversion */
1831         if (sbi->options.isvfat) {
1832                 sbi->nls_io = load_nls(sbi->options.iocharset);
1833                 if (!sbi->nls_io) {
1834                         fat_msg(sb, KERN_ERR, "IO charset %s not found",
1835                                sbi->options.iocharset);
1836                         goto out_fail;
1837                 }
1838         }
1839
1840         error = -ENOMEM;
1841         fat_inode = new_inode(sb);
1842         if (!fat_inode)
1843                 goto out_fail;
1844         sbi->fat_inode = fat_inode;
1845
1846         fsinfo_inode = new_inode(sb);
1847         if (!fsinfo_inode)
1848                 goto out_fail;
1849         fsinfo_inode->i_ino = MSDOS_FSINFO_INO;
1850         sbi->fsinfo_inode = fsinfo_inode;
1851         insert_inode_hash(fsinfo_inode);
1852
1853         root_inode = new_inode(sb);
1854         if (!root_inode)
1855                 goto out_fail;
1856         root_inode->i_ino = MSDOS_ROOT_INO;
1857         inode_set_iversion(root_inode, 1);
1858         error = fat_read_root(root_inode);
1859         if (error < 0) {
1860                 iput(root_inode);
1861                 goto out_fail;
1862         }
1863         error = -ENOMEM;
1864         insert_inode_hash(root_inode);
1865         fat_attach(root_inode, 0);
1866         sb->s_root = d_make_root(root_inode);
1867         if (!sb->s_root) {
1868                 fat_msg(sb, KERN_ERR, "get root inode failed");
1869                 goto out_fail;
1870         }
1871
1872         if (sbi->options.discard) {
1873                 struct request_queue *q = bdev_get_queue(sb->s_bdev);
1874                 if (!blk_queue_discard(q))
1875                         fat_msg(sb, KERN_WARNING,
1876                                         "mounting with \"discard\" option, but "
1877                                         "the device does not support discard");
1878         }
1879
1880         fat_set_state(sb, 1, 0);
1881         return 0;
1882
1883 out_invalid:
1884         error = -EINVAL;
1885         if (!silent)
1886                 fat_msg(sb, KERN_INFO, "Can't find a valid FAT filesystem");
1887
1888 out_fail:
1889         if (fsinfo_inode)
1890                 iput(fsinfo_inode);
1891         if (fat_inode)
1892                 iput(fat_inode);
1893         unload_nls(sbi->nls_io);
1894         unload_nls(sbi->nls_disk);
1895         fat_reset_iocharset(&sbi->options);
1896         sb->s_fs_info = NULL;
1897         kfree(sbi);
1898         return error;
1899 }
1900
1901 EXPORT_SYMBOL_GPL(fat_fill_super);
1902
1903 /*
1904  * helper function for fat_flush_inodes.  This writes both the inode
1905  * and the file data blocks, waiting for in flight data blocks before
1906  * the start of the call.  It does not wait for any io started
1907  * during the call
1908  */
1909 static int writeback_inode(struct inode *inode)
1910 {
1911
1912         int ret;
1913
1914         /* if we used wait=1, sync_inode_metadata waits for the io for the
1915         * inode to finish.  So wait=0 is sent down to sync_inode_metadata
1916         * and filemap_fdatawrite is used for the data blocks
1917         */
1918         ret = sync_inode_metadata(inode, 0);
1919         if (!ret)
1920                 ret = filemap_fdatawrite(inode->i_mapping);
1921         return ret;
1922 }
1923
1924 /*
1925  * write data and metadata corresponding to i1 and i2.  The io is
1926  * started but we do not wait for any of it to finish.
1927  *
1928  * filemap_flush is used for the block device, so if there is a dirty
1929  * page for a block already in flight, we will not wait and start the
1930  * io over again
1931  */
1932 int fat_flush_inodes(struct super_block *sb, struct inode *i1, struct inode *i2)
1933 {
1934         int ret = 0;
1935         if (!MSDOS_SB(sb)->options.flush)
1936                 return 0;
1937         if (i1)
1938                 ret = writeback_inode(i1);
1939         if (!ret && i2)
1940                 ret = writeback_inode(i2);
1941         if (!ret) {
1942                 struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping;
1943                 ret = filemap_flush(mapping);
1944         }
1945         return ret;
1946 }
1947 EXPORT_SYMBOL_GPL(fat_flush_inodes);
1948
1949 static int __init init_fat_fs(void)
1950 {
1951         int err;
1952
1953         err = fat_cache_init();
1954         if (err)
1955                 return err;
1956
1957         err = fat_init_inodecache();
1958         if (err)
1959                 goto failed;
1960
1961         return 0;
1962
1963 failed:
1964         fat_cache_destroy();
1965         return err;
1966 }
1967
1968 static void __exit exit_fat_fs(void)
1969 {
1970         fat_cache_destroy();
1971         fat_destroy_inodecache();
1972 }
1973
1974 module_init(init_fat_fs)
1975 module_exit(exit_fat_fs)
1976
1977 MODULE_LICENSE("GPL");