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_read_folio(struct file *file, struct folio *folio)
 209 {
 210         return mpage_read_folio(folio, fat_get_block);
 211 }
 212
 213 static void fat_readahead(struct readahead_control *rac)
 214 {
 215         mpage_readahead(rac, fat_get_block);
 216 }
 217
 218 static void fat_write_failed(struct address_space *mapping, loff_t to)
 219 {
 220         struct inode *inode = mapping->host;
 221
 222         if (to > inode->i_size) {
 223                 truncate_pagecache(inode, inode->i_size);
 224                 fat_truncate_blocks(inode, inode->i_size);
 225         }
 226 }
 227
 228 static int fat_write_begin(struct file *file, struct address_space *mapping,
 229                         loff_t pos, unsigned len,
 230                         struct page **pagep, void **fsdata)
 231 {
 232         int err;
 233
 234         *pagep = NULL;
 235         err = cont_write_begin(file, mapping, pos, len,
 236                                 pagep, fsdata, fat_get_block,
 237                                 &MSDOS_I(mapping->host)->mmu_private);
 238         if (err < 0)
 239                 fat_write_failed(mapping, pos + len);
 240         return err;
 241 }
 242
 243 static int fat_write_end(struct file *file, struct address_space *mapping,
 244                         loff_t pos, unsigned len, unsigned copied,
 245                         struct page *pagep, void *fsdata)
 246 {
 247         struct inode *inode = mapping->host;
 248         int err;
 249         err = generic_write_end(file, mapping, pos, len, copied, pagep, fsdata);
 250         if (err < len)
 251                 fat_write_failed(mapping, pos + len);
 252         if (!(err < 0) && !(MSDOS_I(inode)->i_attrs & ATTR_ARCH)) {
 253                 fat_truncate_time(inode, NULL, S_CTIME|S_MTIME);
 254                 MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
 255                 mark_inode_dirty(inode);
 256         }
 257         return err;
 258 }
 259
 260 static ssize_t fat_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
 261 {
 262         struct file *file = iocb->ki_filp;
 263         struct address_space *mapping = file->f_mapping;
 264         struct inode *inode = mapping->host;
 265         size_t count = iov_iter_count(iter);
 266         loff_t offset = iocb->ki_pos;
 267         ssize_t ret;
 268
 269         if (iov_iter_rw(iter) == WRITE) {
 270                 /*
 271                  * FIXME: blockdev_direct_IO() doesn't use ->write_begin(),
 272                  * so we need to update the ->mmu_private to block boundary.
 273                  *
 274                  * But we must fill the remaining area or hole by nul for
 275                  * updating ->mmu_private.
 276                  *
 277                  * Return 0, and fallback to normal buffered write.
 278                  */
 279                 loff_t size = offset + count;
 280                 if (MSDOS_I(inode)->mmu_private < size)
 281                         return 0;
 282         }
 283
 284         /*
 285          * FAT need to use the DIO_LOCKING for avoiding the race
 286          * condition of fat_get_block() and ->truncate().
 287          */
 288         ret = blockdev_direct_IO(iocb, inode, iter, fat_get_block);
 289         if (ret < 0 && iov_iter_rw(iter) == WRITE)
 290                 fat_write_failed(mapping, offset + count);
 291
 292         return ret;
 293 }
 294
 295 static int fat_get_block_bmap(struct inode *inode, sector_t iblock,
 296                 struct buffer_head *bh_result, int create)
 297 {
 298         struct super_block *sb = inode->i_sb;
 299         unsigned long max_blocks = bh_result->b_size >> inode->i_blkbits;
 300         int err;
 301         sector_t bmap;
 302         unsigned long mapped_blocks;
 303
 304         BUG_ON(create != 0);
 305
 306         err = fat_bmap(inode, iblock, &bmap, &mapped_blocks, create, true);
 307         if (err)
 308                 return err;
 309
 310         if (bmap) {
 311                 map_bh(bh_result, sb, bmap);
 312                 max_blocks = min(mapped_blocks, max_blocks);
 313         }
 314
 315         bh_result->b_size = max_blocks << sb->s_blocksize_bits;
 316
 317         return 0;
 318 }
 319
 320 static sector_t _fat_bmap(struct address_space *mapping, sector_t block)
 321 {
 322         sector_t blocknr;
 323
 324         /* fat_get_cluster() assumes the requested blocknr isn't truncated. */
 325         down_read(&MSDOS_I(mapping->host)->truncate_lock);
 326         blocknr = generic_block_bmap(mapping, block, fat_get_block_bmap);
 327         up_read(&MSDOS_I(mapping->host)->truncate_lock);
 328
 329         return blocknr;
 330 }
 331
 332 /*
 333  * fat_block_truncate_page() zeroes out a mapping from file offset `from'
 334  * up to the end of the block which corresponds to `from'.
 335  * This is required during truncate to physically zeroout the tail end
 336  * of that block so it doesn't yield old data if the file is later grown.
 337  * Also, avoid causing failure from fsx for cases of "data past EOF"
 338  */
 339 int fat_block_truncate_page(struct inode *inode, loff_t from)
 340 {
 341         return block_truncate_page(inode->i_mapping, from, fat_get_block);
 342 }
 343
 344 static const struct address_space_operations fat_aops = {
 345         .dirty_folio    = block_dirty_folio,
 346         .invalidate_folio = block_invalidate_folio,
 347         .read_folio     = fat_read_folio,
 348         .readahead      = fat_readahead,
 349         .writepage      = fat_writepage,
 350         .writepages     = fat_writepages,
 351         .write_begin    = fat_write_begin,
 352         .write_end      = fat_write_end,
 353         .direct_IO      = fat_direct_IO,
 354         .bmap           = _fat_bmap
 355 };
 356
 357 /*
 358  * New FAT inode stuff. We do the following:
 359  *      a) i_ino is constant and has nothing with on-disk location.
 360  *      b) FAT manages its own cache of directory entries.
 361  *      c) *This* cache is indexed by on-disk location.
 362  *      d) inode has an associated directory entry, all right, but
 363  *              it may be unhashed.
 364  *      e) currently entries are stored within struct inode. That should
 365  *              change.
 366  *      f) we deal with races in the following way:
 367  *              1. readdir() and lookup() do FAT-dir-cache lookup.
 368  *              2. rename() unhashes the F-d-c entry and rehashes it in
 369  *                      a new place.
 370  *              3. unlink() and rmdir() unhash F-d-c entry.
 371  *              4. fat_write_inode() checks whether the thing is unhashed.
 372  *                      If it is we silently return. If it isn't we do bread(),
 373  *                      check if the location is still valid and retry if it
 374  *                      isn't. Otherwise we do changes.
 375  *              5. Spinlock is used to protect hash/unhash/location check/lookup
 376  *              6. fat_evict_inode() unhashes the F-d-c entry.
 377  *              7. lookup() and readdir() do igrab() if they find a F-d-c entry
 378  *                      and consider negative result as cache miss.
 379  */
 380
 381 static void fat_hash_init(struct super_block *sb)
 382 {
 383         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 384         int i;
 385
 386         spin_lock_init(&sbi->inode_hash_lock);
 387         for (i = 0; i < FAT_HASH_SIZE; i++)
 388                 INIT_HLIST_HEAD(&sbi->inode_hashtable[i]);
 389 }
 390
 391 static inline unsigned long fat_hash(loff_t i_pos)
 392 {
 393         return hash_32(i_pos, FAT_HASH_BITS);
 394 }
 395
 396 static void dir_hash_init(struct super_block *sb)
 397 {
 398         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 399         int i;
 400
 401         spin_lock_init(&sbi->dir_hash_lock);
 402         for (i = 0; i < FAT_HASH_SIZE; i++)
 403                 INIT_HLIST_HEAD(&sbi->dir_hashtable[i]);
 404 }
 405
 406 void fat_attach(struct inode *inode, loff_t i_pos)
 407 {
 408         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 409
 410         if (inode->i_ino != MSDOS_ROOT_INO) {
 411                 struct hlist_head *head =   sbi->inode_hashtable
 412                                           + fat_hash(i_pos);
 413
 414                 spin_lock(&sbi->inode_hash_lock);
 415                 MSDOS_I(inode)->i_pos = i_pos;
 416                 hlist_add_head(&MSDOS_I(inode)->i_fat_hash, head);
 417                 spin_unlock(&sbi->inode_hash_lock);
 418         }
 419
 420         /* If NFS support is enabled, cache the mapping of start cluster
 421          * to directory inode. This is used during reconnection of
 422          * dentries to the filesystem root.
 423          */
 424         if (S_ISDIR(inode->i_mode) && sbi->options.nfs) {
 425                 struct hlist_head *d_head = sbi->dir_hashtable;
 426                 d_head += fat_dir_hash(MSDOS_I(inode)->i_logstart);
 427
 428                 spin_lock(&sbi->dir_hash_lock);
 429                 hlist_add_head(&MSDOS_I(inode)->i_dir_hash, d_head);
 430                 spin_unlock(&sbi->dir_hash_lock);
 431         }
 432 }
 433 EXPORT_SYMBOL_GPL(fat_attach);
 434
 435 void fat_detach(struct inode *inode)
 436 {
 437         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 438         spin_lock(&sbi->inode_hash_lock);
 439         MSDOS_I(inode)->i_pos = 0;
 440         hlist_del_init(&MSDOS_I(inode)->i_fat_hash);
 441         spin_unlock(&sbi->inode_hash_lock);
 442
 443         if (S_ISDIR(inode->i_mode) && sbi->options.nfs) {
 444                 spin_lock(&sbi->dir_hash_lock);
 445                 hlist_del_init(&MSDOS_I(inode)->i_dir_hash);
 446                 spin_unlock(&sbi->dir_hash_lock);
 447         }
 448 }
 449 EXPORT_SYMBOL_GPL(fat_detach);
 450
 451 struct inode *fat_iget(struct super_block *sb, loff_t i_pos)
 452 {
 453         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 454         struct hlist_head *head = sbi->inode_hashtable + fat_hash(i_pos);
 455         struct msdos_inode_info *i;
 456         struct inode *inode = NULL;
 457
 458         spin_lock(&sbi->inode_hash_lock);
 459         hlist_for_each_entry(i, head, i_fat_hash) {
 460                 BUG_ON(i->vfs_inode.i_sb != sb);
 461                 if (i->i_pos != i_pos)
 462                         continue;
 463                 inode = igrab(&i->vfs_inode);
 464                 if (inode)
 465                         break;
 466         }
 467         spin_unlock(&sbi->inode_hash_lock);
 468         return inode;
 469 }
 470
 471 static int is_exec(unsigned char *extension)
 472 {
 473         unsigned char exe_extensions[] = "EXECOMBAT", *walk;
 474
 475         for (walk = exe_extensions; *walk; walk += 3)
 476                 if (!strncmp(extension, walk, 3))
 477                         return 1;
 478         return 0;
 479 }
 480
 481 static int fat_calc_dir_size(struct inode *inode)
 482 {
 483         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 484         int ret, fclus, dclus;
 485
 486         inode->i_size = 0;
 487         if (MSDOS_I(inode)->i_start == 0)
 488                 return 0;
 489
 490         ret = fat_get_cluster(inode, FAT_ENT_EOF, &fclus, &dclus);
 491         if (ret < 0)
 492                 return ret;
 493         inode->i_size = (fclus + 1) << sbi->cluster_bits;
 494
 495         return 0;
 496 }
 497
 498 static int fat_validate_dir(struct inode *dir)
 499 {
 500         struct super_block *sb = dir->i_sb;
 501
 502         if (dir->i_nlink < 2) {
 503                 /* Directory should have "."/".." entries at least. */
 504                 fat_fs_error(sb, "corrupted directory (invalid entries)");
 505                 return -EIO;
 506         }
 507         if (MSDOS_I(dir)->i_start == 0 ||
 508             MSDOS_I(dir)->i_start == MSDOS_SB(sb)->root_cluster) {
 509                 /* Directory should point valid cluster. */
 510                 fat_fs_error(sb, "corrupted directory (invalid i_start)");
 511                 return -EIO;
 512         }
 513         return 0;
 514 }
 515
 516 /* doesn't deal with root inode */
 517 int fat_fill_inode(struct inode *inode, struct msdos_dir_entry *de)
 518 {
 519         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 520         int error;
 521
 522         MSDOS_I(inode)->i_pos = 0;
 523         inode->i_uid = sbi->options.fs_uid;
 524         inode->i_gid = sbi->options.fs_gid;
 525         inode_inc_iversion(inode);
 526         inode->i_generation = prandom_u32();
 527
 528         if ((de->attr & ATTR_DIR) && !IS_FREE(de->name)) {
 529                 inode->i_generation &= ~1;
 530                 inode->i_mode = fat_make_mode(sbi, de->attr, S_IRWXUGO);
 531                 inode->i_op = sbi->dir_ops;
 532                 inode->i_fop = &fat_dir_operations;
 533
 534                 MSDOS_I(inode)->i_start = fat_get_start(sbi, de);
 535                 MSDOS_I(inode)->i_logstart = MSDOS_I(inode)->i_start;
 536                 error = fat_calc_dir_size(inode);
 537                 if (error < 0)
 538                         return error;
 539                 MSDOS_I(inode)->mmu_private = inode->i_size;
 540
 541                 set_nlink(inode, fat_subdirs(inode));
 542
 543                 error = fat_validate_dir(inode);
 544                 if (error < 0)
 545                         return error;
 546         } else { /* not a directory */
 547                 inode->i_generation |= 1;
 548                 inode->i_mode = fat_make_mode(sbi, de->attr,
 549                         ((sbi->options.showexec && !is_exec(de->name + 8))
 550                          ? S_IRUGO|S_IWUGO : S_IRWXUGO));
 551                 MSDOS_I(inode)->i_start = fat_get_start(sbi, de);
 552
 553                 MSDOS_I(inode)->i_logstart = MSDOS_I(inode)->i_start;
 554                 inode->i_size = le32_to_cpu(de->size);
 555                 inode->i_op = &fat_file_inode_operations;
 556                 inode->i_fop = &fat_file_operations;
 557                 inode->i_mapping->a_ops = &fat_aops;
 558                 MSDOS_I(inode)->mmu_private = inode->i_size;
 559         }
 560         if (de->attr & ATTR_SYS) {
 561                 if (sbi->options.sys_immutable)
 562                         inode->i_flags |= S_IMMUTABLE;
 563         }
 564         fat_save_attrs(inode, de->attr);
 565
 566         inode->i_blocks = ((inode->i_size + (sbi->cluster_size - 1))
 567                            & ~((loff_t)sbi->cluster_size - 1)) >> 9;
 568
 569         fat_time_fat2unix(sbi, &inode->i_mtime, de->time, de->date, 0);
 570         inode->i_ctime = inode->i_mtime;
 571         if (sbi->options.isvfat) {
 572                 fat_time_fat2unix(sbi, &inode->i_atime, 0, de->adate, 0);
 573                 fat_time_fat2unix(sbi, &MSDOS_I(inode)->i_crtime, de->ctime,
 574                                   de->cdate, de->ctime_cs);
 575         } else
 576                 inode->i_atime = fat_truncate_atime(sbi, &inode->i_mtime);
 577
 578         return 0;
 579 }
 580
 581 static inline void fat_lock_build_inode(struct msdos_sb_info *sbi)
 582 {
 583         if (sbi->options.nfs == FAT_NFS_NOSTALE_RO)
 584                 mutex_lock(&sbi->nfs_build_inode_lock);
 585 }
 586
 587 static inline void fat_unlock_build_inode(struct msdos_sb_info *sbi)
 588 {
 589         if (sbi->options.nfs == FAT_NFS_NOSTALE_RO)
 590                 mutex_unlock(&sbi->nfs_build_inode_lock);
 591 }
 592
 593 struct inode *fat_build_inode(struct super_block *sb,
 594                         struct msdos_dir_entry *de, loff_t i_pos)
 595 {
 596         struct inode *inode;
 597         int err;
 598
 599         fat_lock_build_inode(MSDOS_SB(sb));
 600         inode = fat_iget(sb, i_pos);
 601         if (inode)
 602                 goto out;
 603         inode = new_inode(sb);
 604         if (!inode) {
 605                 inode = ERR_PTR(-ENOMEM);
 606                 goto out;
 607         }
 608         inode->i_ino = iunique(sb, MSDOS_ROOT_INO);
 609         inode_set_iversion(inode, 1);
 610         err = fat_fill_inode(inode, de);
 611         if (err) {
 612                 iput(inode);
 613                 inode = ERR_PTR(err);
 614                 goto out;
 615         }
 616         fat_attach(inode, i_pos);
 617         insert_inode_hash(inode);
 618 out:
 619         fat_unlock_build_inode(MSDOS_SB(sb));
 620         return inode;
 621 }
 622
 623 EXPORT_SYMBOL_GPL(fat_build_inode);
 624
 625 static int __fat_write_inode(struct inode *inode, int wait);
 626
 627 static void fat_free_eofblocks(struct inode *inode)
 628 {
 629         /* Release unwritten fallocated blocks on inode eviction. */
 630         if ((inode->i_blocks << 9) >
 631                         round_up(MSDOS_I(inode)->mmu_private,
 632                                 MSDOS_SB(inode->i_sb)->cluster_size)) {
 633                 int err;
 634
 635                 fat_truncate_blocks(inode, MSDOS_I(inode)->mmu_private);
 636                 /* Fallocate results in updating the i_start/iogstart
 637                  * for the zero byte file. So, make it return to
 638                  * original state during evict and commit it to avoid
 639                  * any corruption on the next access to the cluster
 640                  * chain for the file.
 641                  */
 642                 err = __fat_write_inode(inode, inode_needs_sync(inode));
 643                 if (err) {
 644                         fat_msg(inode->i_sb, KERN_WARNING, "Failed to "
 645                                         "update on disk inode for unused "
 646                                         "fallocated blocks, inode could be "
 647                                         "corrupted. Please run fsck");
 648                 }
 649
 650         }
 651 }
 652
 653 static void fat_evict_inode(struct inode *inode)
 654 {
 655         truncate_inode_pages_final(&inode->i_data);
 656         if (!inode->i_nlink) {
 657                 inode->i_size = 0;
 658                 fat_truncate_blocks(inode, 0);
 659         } else
 660                 fat_free_eofblocks(inode);
 661
 662         invalidate_inode_buffers(inode);
 663         clear_inode(inode);
 664         fat_cache_inval_inode(inode);
 665         fat_detach(inode);
 666 }
 667
 668 static void fat_set_state(struct super_block *sb,
 669                         unsigned int set, unsigned int force)
 670 {
 671         struct buffer_head *bh;
 672         struct fat_boot_sector *b;
 673         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 674
 675         /* do not change any thing if mounted read only */
 676         if (sb_rdonly(sb) && !force)
 677                 return;
 678
 679         /* do not change state if fs was dirty */
 680         if (sbi->dirty) {
 681                 /* warn only on set (mount). */
 682                 if (set)
 683                         fat_msg(sb, KERN_WARNING, "Volume was not properly "
 684                                 "unmounted. Some data may be corrupt. "
 685                                 "Please run fsck.");
 686                 return;
 687         }
 688
 689         bh = sb_bread(sb, 0);
 690         if (bh == NULL) {
 691                 fat_msg(sb, KERN_ERR, "unable to read boot sector "
 692                         "to mark fs as dirty");
 693                 return;
 694         }
 695
 696         b = (struct fat_boot_sector *) bh->b_data;
 697
 698         if (is_fat32(sbi)) {
 699                 if (set)
 700                         b->fat32.state |= FAT_STATE_DIRTY;
 701                 else
 702                         b->fat32.state &= ~FAT_STATE_DIRTY;
 703         } else /* fat 16 and 12 */ {
 704                 if (set)
 705                         b->fat16.state |= FAT_STATE_DIRTY;
 706                 else
 707                         b->fat16.state &= ~FAT_STATE_DIRTY;
 708         }
 709
 710         mark_buffer_dirty(bh);
 711         sync_dirty_buffer(bh);
 712         brelse(bh);
 713 }
 714
 715 static void fat_reset_iocharset(struct fat_mount_options *opts)
 716 {
 717         if (opts->iocharset != fat_default_iocharset) {
 718                 /* Note: opts->iocharset can be NULL here */
 719                 kfree(opts->iocharset);
 720                 opts->iocharset = fat_default_iocharset;
 721         }
 722 }
 723
 724 static void delayed_free(struct rcu_head *p)
 725 {
 726         struct msdos_sb_info *sbi = container_of(p, struct msdos_sb_info, rcu);
 727         unload_nls(sbi->nls_disk);
 728         unload_nls(sbi->nls_io);
 729         fat_reset_iocharset(&sbi->options);
 730         kfree(sbi);
 731 }
 732
 733 static void fat_put_super(struct super_block *sb)
 734 {
 735         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 736
 737         fat_set_state(sb, 0, 0);
 738
 739         iput(sbi->fsinfo_inode);
 740         iput(sbi->fat_inode);
 741
 742         call_rcu(&sbi->rcu, delayed_free);
 743 }
 744
 745 static struct kmem_cache *fat_inode_cachep;
 746
 747 static struct inode *fat_alloc_inode(struct super_block *sb)
 748 {
 749         struct msdos_inode_info *ei;
 750         ei = alloc_inode_sb(sb, fat_inode_cachep, GFP_NOFS);
 751         if (!ei)
 752                 return NULL;
 753
 754         init_rwsem(&ei->truncate_lock);
 755         /* Zeroing to allow iput() even if partial initialized inode. */
 756         ei->mmu_private = 0;
 757         ei->i_start = 0;
 758         ei->i_logstart = 0;
 759         ei->i_attrs = 0;
 760         ei->i_pos = 0;
 761         ei->i_crtime.tv_sec = 0;
 762         ei->i_crtime.tv_nsec = 0;
 763
 764         return &ei->vfs_inode;
 765 }
 766
 767 static void fat_free_inode(struct inode *inode)
 768 {
 769         kmem_cache_free(fat_inode_cachep, MSDOS_I(inode));
 770 }
 771
 772 static void init_once(void *foo)
 773 {
 774         struct msdos_inode_info *ei = (struct msdos_inode_info *)foo;
 775
 776         spin_lock_init(&ei->cache_lru_lock);
 777         ei->nr_caches = 0;
 778         ei->cache_valid_id = FAT_CACHE_VALID + 1;
 779         INIT_LIST_HEAD(&ei->cache_lru);
 780         INIT_HLIST_NODE(&ei->i_fat_hash);
 781         INIT_HLIST_NODE(&ei->i_dir_hash);
 782         inode_init_once(&ei->vfs_inode);
 783 }
 784
 785 static int __init fat_init_inodecache(void)
 786 {
 787         fat_inode_cachep = kmem_cache_create("fat_inode_cache",
 788                                              sizeof(struct msdos_inode_info),
 789                                              0, (SLAB_RECLAIM_ACCOUNT|
 790                                                 SLAB_MEM_SPREAD|SLAB_ACCOUNT),
 791                                              init_once);
 792         if (fat_inode_cachep == NULL)
 793                 return -ENOMEM;
 794         return 0;
 795 }
 796
 797 static void __exit fat_destroy_inodecache(void)
 798 {
 799         /*
 800          * Make sure all delayed rcu free inodes are flushed before we
 801          * destroy cache.
 802          */
 803         rcu_barrier();
 804         kmem_cache_destroy(fat_inode_cachep);
 805 }
 806
 807 static int fat_remount(struct super_block *sb, int *flags, char *data)
 808 {
 809         bool new_rdonly;
 810         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 811         *flags |= SB_NODIRATIME | (sbi->options.isvfat ? 0 : SB_NOATIME);
 812
 813         sync_filesystem(sb);
 814
 815         /* make sure we update state on remount. */
 816         new_rdonly = *flags & SB_RDONLY;
 817         if (new_rdonly != sb_rdonly(sb)) {
 818                 if (new_rdonly)
 819                         fat_set_state(sb, 0, 0);
 820                 else
 821                         fat_set_state(sb, 1, 1);
 822         }
 823         return 0;
 824 }
 825
 826 static int fat_statfs(struct dentry *dentry, struct kstatfs *buf)
 827 {
 828         struct super_block *sb = dentry->d_sb;
 829         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 830         u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
 831
 832         /* If the count of free cluster is still unknown, counts it here. */
 833         if (sbi->free_clusters == -1 || !sbi->free_clus_valid) {
 834                 int err = fat_count_free_clusters(dentry->d_sb);
 835                 if (err)
 836                         return err;
 837         }
 838
 839         buf->f_type = dentry->d_sb->s_magic;
 840         buf->f_bsize = sbi->cluster_size;
 841         buf->f_blocks = sbi->max_cluster - FAT_START_ENT;
 842         buf->f_bfree = sbi->free_clusters;
 843         buf->f_bavail = sbi->free_clusters;
 844         buf->f_fsid = u64_to_fsid(id);
 845         buf->f_namelen =
 846                 (sbi->options.isvfat ? FAT_LFN_LEN : 12) * NLS_MAX_CHARSET_SIZE;
 847
 848         return 0;
 849 }
 850
 851 static int __fat_write_inode(struct inode *inode, int wait)
 852 {
 853         struct super_block *sb = inode->i_sb;
 854         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 855         struct buffer_head *bh;
 856         struct msdos_dir_entry *raw_entry;
 857         loff_t i_pos;
 858         sector_t blocknr;
 859         int err, offset;
 860
 861         if (inode->i_ino == MSDOS_ROOT_INO)
 862                 return 0;
 863
 864 retry:
 865         i_pos = fat_i_pos_read(sbi, inode);
 866         if (!i_pos)
 867                 return 0;
 868
 869         fat_get_blknr_offset(sbi, i_pos, &blocknr, &offset);
 870         bh = sb_bread(sb, blocknr);
 871         if (!bh) {
 872                 fat_msg(sb, KERN_ERR, "unable to read inode block "
 873                        "for updating (i_pos %lld)", i_pos);
 874                 return -EIO;
 875         }
 876         spin_lock(&sbi->inode_hash_lock);
 877         if (i_pos != MSDOS_I(inode)->i_pos) {
 878                 spin_unlock(&sbi->inode_hash_lock);
 879                 brelse(bh);
 880                 goto retry;
 881         }
 882
 883         raw_entry = &((struct msdos_dir_entry *) (bh->b_data))[offset];
 884         if (S_ISDIR(inode->i_mode))
 885                 raw_entry->size = 0;
 886         else
 887                 raw_entry->size = cpu_to_le32(inode->i_size);
 888         raw_entry->attr = fat_make_attrs(inode);
 889         fat_set_start(raw_entry, MSDOS_I(inode)->i_logstart);
 890         fat_time_unix2fat(sbi, &inode->i_mtime, &raw_entry->time,
 891                           &raw_entry->date, NULL);
 892         if (sbi->options.isvfat) {
 893                 __le16 atime;
 894                 fat_time_unix2fat(sbi, &inode->i_atime, &atime,
 895                                   &raw_entry->adate, NULL);
 896                 fat_time_unix2fat(sbi, &MSDOS_I(inode)->i_crtime, &raw_entry->ctime,
 897                                   &raw_entry->cdate, &raw_entry->ctime_cs);
 898         }
 899         spin_unlock(&sbi->inode_hash_lock);
 900         mark_buffer_dirty(bh);
 901         err = 0;
 902         if (wait)
 903                 err = sync_dirty_buffer(bh);
 904         brelse(bh);
 905         return err;
 906 }
 907
 908 static int fat_write_inode(struct inode *inode, struct writeback_control *wbc)
 909 {
 910         int err;
 911
 912         if (inode->i_ino == MSDOS_FSINFO_INO) {
 913                 struct super_block *sb = inode->i_sb;
 914
 915                 mutex_lock(&MSDOS_SB(sb)->s_lock);
 916                 err = fat_clusters_flush(sb);
 917                 mutex_unlock(&MSDOS_SB(sb)->s_lock);
 918         } else
 919                 err = __fat_write_inode(inode, wbc->sync_mode == WB_SYNC_ALL);
 920
 921         return err;
 922 }
 923
 924 int fat_sync_inode(struct inode *inode)
 925 {
 926         return __fat_write_inode(inode, 1);
 927 }
 928
 929 EXPORT_SYMBOL_GPL(fat_sync_inode);
 930
 931 static int fat_show_options(struct seq_file *m, struct dentry *root);
 932 static const struct super_operations fat_sops = {
 933         .alloc_inode    = fat_alloc_inode,
 934         .free_inode     = fat_free_inode,
 935         .write_inode    = fat_write_inode,
 936         .evict_inode    = fat_evict_inode,
 937         .put_super      = fat_put_super,
 938         .statfs         = fat_statfs,
 939         .remount_fs     = fat_remount,
 940
 941         .show_options   = fat_show_options,
 942 };
 943
 944 static int fat_show_options(struct seq_file *m, struct dentry *root)
 945 {
 946         struct msdos_sb_info *sbi = MSDOS_SB(root->d_sb);
 947         struct fat_mount_options *opts = &sbi->options;
 948         int isvfat = opts->isvfat;
 949
 950         if (!uid_eq(opts->fs_uid, GLOBAL_ROOT_UID))
 951                 seq_printf(m, ",uid=%u",
 952                                 from_kuid_munged(&init_user_ns, opts->fs_uid));
 953         if (!gid_eq(opts->fs_gid, GLOBAL_ROOT_GID))
 954                 seq_printf(m, ",gid=%u",
 955                                 from_kgid_munged(&init_user_ns, opts->fs_gid));
 956         seq_printf(m, ",fmask=%04o", opts->fs_fmask);
 957         seq_printf(m, ",dmask=%04o", opts->fs_dmask);
 958         if (opts->allow_utime)
 959                 seq_printf(m, ",allow_utime=%04o", opts->allow_utime);
 960         if (sbi->nls_disk)
 961                 /* strip "cp" prefix from displayed option */
 962                 seq_printf(m, ",codepage=%s", &sbi->nls_disk->charset[2]);
 963         if (isvfat) {
 964                 if (sbi->nls_io)
 965                         seq_printf(m, ",iocharset=%s", sbi->nls_io->charset);
 966
 967                 switch (opts->shortname) {
 968                 case VFAT_SFN_DISPLAY_WIN95 | VFAT_SFN_CREATE_WIN95:
 969                         seq_puts(m, ",shortname=win95");
 970                         break;
 971                 case VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WINNT:
 972                         seq_puts(m, ",shortname=winnt");
 973                         break;
 974                 case VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WIN95:
 975                         seq_puts(m, ",shortname=mixed");
 976                         break;
 977                 case VFAT_SFN_DISPLAY_LOWER | VFAT_SFN_CREATE_WIN95:
 978                         seq_puts(m, ",shortname=lower");
 979                         break;
 980                 default:
 981                         seq_puts(m, ",shortname=unknown");
 982                         break;
 983                 }
 984         }
 985         if (opts->name_check != 'n')
 986                 seq_printf(m, ",check=%c", opts->name_check);
 987         if (opts->usefree)
 988                 seq_puts(m, ",usefree");
 989         if (opts->quiet)
 990                 seq_puts(m, ",quiet");
 991         if (opts->showexec)
 992                 seq_puts(m, ",showexec");
 993         if (opts->sys_immutable)
 994                 seq_puts(m, ",sys_immutable");
 995         if (!isvfat) {
 996                 if (opts->dotsOK)
 997                         seq_puts(m, ",dotsOK=yes");
 998                 if (opts->nocase)
 999                         seq_puts(m, ",nocase");
1000         } else {
1001                 if (opts->utf8)
1002                         seq_puts(m, ",utf8");
1003                 if (opts->unicode_xlate)
1004                         seq_puts(m, ",uni_xlate");
1005                 if (!opts->numtail)
1006                         seq_puts(m, ",nonumtail");
1007                 if (opts->rodir)
1008                         seq_puts(m, ",rodir");
1009         }
1010         if (opts->flush)
1011                 seq_puts(m, ",flush");
1012         if (opts->tz_set) {
1013                 if (opts->time_offset)
1014                         seq_printf(m, ",time_offset=%d", opts->time_offset);
1015                 else
1016                         seq_puts(m, ",tz=UTC");
1017         }
1018         if (opts->errors == FAT_ERRORS_CONT)
1019                 seq_puts(m, ",errors=continue");
1020         else if (opts->errors == FAT_ERRORS_PANIC)
1021                 seq_puts(m, ",errors=panic");
1022         else
1023                 seq_puts(m, ",errors=remount-ro");
1024         if (opts->nfs == FAT_NFS_NOSTALE_RO)
1025                 seq_puts(m, ",nfs=nostale_ro");
1026         else if (opts->nfs)
1027                 seq_puts(m, ",nfs=stale_rw");
1028         if (opts->discard)
1029                 seq_puts(m, ",discard");
1030         if (opts->dos1xfloppy)
1031                 seq_puts(m, ",dos1xfloppy");
1032
1033         return 0;
1034 }
1035
1036 enum {
1037         Opt_check_n, Opt_check_r, Opt_check_s, Opt_uid, Opt_gid,
1038         Opt_umask, Opt_dmask, Opt_fmask, Opt_allow_utime, Opt_codepage,
1039         Opt_usefree, Opt_nocase, Opt_quiet, Opt_showexec, Opt_debug,
1040         Opt_immutable, Opt_dots, Opt_nodots,
1041         Opt_charset, Opt_shortname_lower, Opt_shortname_win95,
1042         Opt_shortname_winnt, Opt_shortname_mixed, Opt_utf8_no, Opt_utf8_yes,
1043         Opt_uni_xl_no, Opt_uni_xl_yes, Opt_nonumtail_no, Opt_nonumtail_yes,
1044         Opt_obsolete, Opt_flush, Opt_tz_utc, Opt_rodir, Opt_err_cont,
1045         Opt_err_panic, Opt_err_ro, Opt_discard, Opt_nfs, Opt_time_offset,
1046         Opt_nfs_stale_rw, Opt_nfs_nostale_ro, Opt_err, Opt_dos1xfloppy,
1047 };
1048
1049 static const match_table_t fat_tokens = {
1050         {Opt_check_r, "check=relaxed"},
1051         {Opt_check_s, "check=strict"},
1052         {Opt_check_n, "check=normal"},
1053         {Opt_check_r, "check=r"},
1054         {Opt_check_s, "check=s"},
1055         {Opt_check_n, "check=n"},
1056         {Opt_uid, "uid=%u"},
1057         {Opt_gid, "gid=%u"},
1058         {Opt_umask, "umask=%o"},
1059         {Opt_dmask, "dmask=%o"},
1060         {Opt_fmask, "fmask=%o"},
1061         {Opt_allow_utime, "allow_utime=%o"},
1062         {Opt_codepage, "codepage=%u"},
1063         {Opt_usefree, "usefree"},
1064         {Opt_nocase, "nocase"},
1065         {Opt_quiet, "quiet"},
1066         {Opt_showexec, "showexec"},
1067         {Opt_debug, "debug"},
1068         {Opt_immutable, "sys_immutable"},
1069         {Opt_flush, "flush"},
1070         {Opt_tz_utc, "tz=UTC"},
1071         {Opt_time_offset, "time_offset=%d"},
1072         {Opt_err_cont, "errors=continue"},
1073         {Opt_err_panic, "errors=panic"},
1074         {Opt_err_ro, "errors=remount-ro"},
1075         {Opt_discard, "discard"},
1076         {Opt_nfs_stale_rw, "nfs"},
1077         {Opt_nfs_stale_rw, "nfs=stale_rw"},
1078         {Opt_nfs_nostale_ro, "nfs=nostale_ro"},
1079         {Opt_dos1xfloppy, "dos1xfloppy"},
1080         {Opt_obsolete, "conv=binary"},
1081         {Opt_obsolete, "conv=text"},
1082         {Opt_obsolete, "conv=auto"},
1083         {Opt_obsolete, "conv=b"},
1084         {Opt_obsolete, "conv=t"},
1085         {Opt_obsolete, "conv=a"},
1086         {Opt_obsolete, "fat=%u"},
1087         {Opt_obsolete, "blocksize=%u"},
1088         {Opt_obsolete, "cvf_format=%20s"},
1089         {Opt_obsolete, "cvf_options=%100s"},
1090         {Opt_obsolete, "posix"},
1091         {Opt_err, NULL},
1092 };
1093 static const match_table_t msdos_tokens = {
1094         {Opt_nodots, "nodots"},
1095         {Opt_nodots, "dotsOK=no"},
1096         {Opt_dots, "dots"},
1097         {Opt_dots, "dotsOK=yes"},
1098         {Opt_err, NULL}
1099 };
1100 static const match_table_t vfat_tokens = {
1101         {Opt_charset, "iocharset=%s"},
1102         {Opt_shortname_lower, "shortname=lower"},
1103         {Opt_shortname_win95, "shortname=win95"},
1104         {Opt_shortname_winnt, "shortname=winnt"},
1105         {Opt_shortname_mixed, "shortname=mixed"},
1106         {Opt_utf8_no, "utf8=0"},                /* 0 or no or false */
1107         {Opt_utf8_no, "utf8=no"},
1108         {Opt_utf8_no, "utf8=false"},
1109         {Opt_utf8_yes, "utf8=1"},               /* empty or 1 or yes or true */
1110         {Opt_utf8_yes, "utf8=yes"},
1111         {Opt_utf8_yes, "utf8=true"},
1112         {Opt_utf8_yes, "utf8"},
1113         {Opt_uni_xl_no, "uni_xlate=0"},         /* 0 or no or false */
1114         {Opt_uni_xl_no, "uni_xlate=no"},
1115         {Opt_uni_xl_no, "uni_xlate=false"},
1116         {Opt_uni_xl_yes, "uni_xlate=1"},        /* empty or 1 or yes or true */
1117         {Opt_uni_xl_yes, "uni_xlate=yes"},
1118         {Opt_uni_xl_yes, "uni_xlate=true"},
1119         {Opt_uni_xl_yes, "uni_xlate"},
1120         {Opt_nonumtail_no, "nonumtail=0"},      /* 0 or no or false */
1121         {Opt_nonumtail_no, "nonumtail=no"},
1122         {Opt_nonumtail_no, "nonumtail=false"},
1123         {Opt_nonumtail_yes, "nonumtail=1"},     /* empty or 1 or yes or true */
1124         {Opt_nonumtail_yes, "nonumtail=yes"},
1125         {Opt_nonumtail_yes, "nonumtail=true"},
1126         {Opt_nonumtail_yes, "nonumtail"},
1127         {Opt_rodir, "rodir"},
1128         {Opt_err, NULL}
1129 };
1130
1131 static int parse_options(struct super_block *sb, char *options, int is_vfat,
1132                          int silent, int *debug, struct fat_mount_options *opts)
1133 {
1134         char *p;
1135         substring_t args[MAX_OPT_ARGS];
1136         int option;
1137         char *iocharset;
1138
1139         opts->isvfat = is_vfat;
1140
1141         opts->fs_uid = current_uid();
1142         opts->fs_gid = current_gid();
1143         opts->fs_fmask = opts->fs_dmask = current_umask();
1144         opts->allow_utime = -1;
1145         opts->codepage = fat_default_codepage;
1146         fat_reset_iocharset(opts);
1147         if (is_vfat) {
1148                 opts->shortname = VFAT_SFN_DISPLAY_WINNT|VFAT_SFN_CREATE_WIN95;
1149                 opts->rodir = 0;
1150         } else {
1151                 opts->shortname = 0;
1152                 opts->rodir = 1;
1153         }
1154         opts->name_check = 'n';
1155         opts->quiet = opts->showexec = opts->sys_immutable = opts->dotsOK =  0;
1156         opts->unicode_xlate = 0;
1157         opts->numtail = 1;
1158         opts->usefree = opts->nocase = 0;
1159         opts->tz_set = 0;
1160         opts->nfs = 0;
1161         opts->errors = FAT_ERRORS_RO;
1162         *debug = 0;
1163
1164         opts->utf8 = IS_ENABLED(CONFIG_FAT_DEFAULT_UTF8) && is_vfat;
1165
1166         if (!options)
1167                 goto out;
1168
1169         while ((p = strsep(&options, ",")) != NULL) {
1170                 int token;
1171                 if (!*p)
1172                         continue;
1173
1174                 token = match_token(p, fat_tokens, args);
1175                 if (token == Opt_err) {
1176                         if (is_vfat)
1177                                 token = match_token(p, vfat_tokens, args);
1178                         else
1179                                 token = match_token(p, msdos_tokens, args);
1180                 }
1181                 switch (token) {
1182                 case Opt_check_s:
1183                         opts->name_check = 's';
1184                         break;
1185                 case Opt_check_r:
1186                         opts->name_check = 'r';
1187                         break;
1188                 case Opt_check_n:
1189                         opts->name_check = 'n';
1190                         break;
1191                 case Opt_usefree:
1192                         opts->usefree = 1;
1193                         break;
1194                 case Opt_nocase:
1195                         if (!is_vfat)
1196                                 opts->nocase = 1;
1197                         else {
1198                                 /* for backward compatibility */
1199                                 opts->shortname = VFAT_SFN_DISPLAY_WIN95
1200                                         | VFAT_SFN_CREATE_WIN95;
1201                         }
1202                         break;
1203                 case Opt_quiet:
1204                         opts->quiet = 1;
1205                         break;
1206                 case Opt_showexec:
1207                         opts->showexec = 1;
1208                         break;
1209                 case Opt_debug:
1210                         *debug = 1;
1211                         break;
1212                 case Opt_immutable:
1213                         opts->sys_immutable = 1;
1214                         break;
1215                 case Opt_uid:
1216                         if (match_int(&args[0], &option))
1217                                 return -EINVAL;
1218                         opts->fs_uid = make_kuid(current_user_ns(), option);
1219                         if (!uid_valid(opts->fs_uid))
1220                                 return -EINVAL;
1221                         break;
1222                 case Opt_gid:
1223                         if (match_int(&args[0], &option))
1224                                 return -EINVAL;
1225                         opts->fs_gid = make_kgid(current_user_ns(), option);
1226                         if (!gid_valid(opts->fs_gid))
1227                                 return -EINVAL;
1228                         break;
1229                 case Opt_umask:
1230                         if (match_octal(&args[0], &option))
1231                                 return -EINVAL;
1232                         opts->fs_fmask = opts->fs_dmask = option;
1233                         break;
1234                 case Opt_dmask:
1235                         if (match_octal(&args[0], &option))
1236                                 return -EINVAL;
1237                         opts->fs_dmask = option;
1238                         break;
1239                 case Opt_fmask:
1240                         if (match_octal(&args[0], &option))
1241                                 return -EINVAL;
1242                         opts->fs_fmask = option;
1243                         break;
1244                 case Opt_allow_utime:
1245                         if (match_octal(&args[0], &option))
1246                                 return -EINVAL;
1247                         opts->allow_utime = option & (S_IWGRP | S_IWOTH);
1248                         break;
1249                 case Opt_codepage:
1250                         if (match_int(&args[0], &option))
1251                                 return -EINVAL;
1252                         opts->codepage = option;
1253                         break;
1254                 case Opt_flush:
1255                         opts->flush = 1;
1256                         break;
1257                 case Opt_time_offset:
1258                         if (match_int(&args[0], &option))
1259                                 return -EINVAL;
1260                         /*
1261                          * GMT+-12 zones may have DST corrections so at least
1262                          * 13 hours difference is needed. Make the limit 24
1263                          * just in case someone invents something unusual.
1264                          */
1265                         if (option < -24 * 60 || option > 24 * 60)
1266                                 return -EINVAL;
1267                         opts->tz_set = 1;
1268                         opts->time_offset = option;
1269                         break;
1270                 case Opt_tz_utc:
1271                         opts->tz_set = 1;
1272                         opts->time_offset = 0;
1273                         break;
1274                 case Opt_err_cont:
1275                         opts->errors = FAT_ERRORS_CONT;
1276                         break;
1277                 case Opt_err_panic:
1278                         opts->errors = FAT_ERRORS_PANIC;
1279                         break;
1280                 case Opt_err_ro:
1281                         opts->errors = FAT_ERRORS_RO;
1282                         break;
1283                 case Opt_nfs_stale_rw:
1284                         opts->nfs = FAT_NFS_STALE_RW;
1285                         break;
1286                 case Opt_nfs_nostale_ro:
1287                         opts->nfs = FAT_NFS_NOSTALE_RO;
1288                         break;
1289                 case Opt_dos1xfloppy:
1290                         opts->dos1xfloppy = 1;
1291                         break;
1292
1293                 /* msdos specific */
1294                 case Opt_dots:
1295                         opts->dotsOK = 1;
1296                         break;
1297                 case Opt_nodots:
1298                         opts->dotsOK = 0;
1299                         break;
1300
1301                 /* vfat specific */
1302                 case Opt_charset:
1303                         fat_reset_iocharset(opts);
1304                         iocharset = match_strdup(&args[0]);
1305                         if (!iocharset)
1306                                 return -ENOMEM;
1307                         opts->iocharset = iocharset;
1308                         break;
1309                 case Opt_shortname_lower:
1310                         opts->shortname = VFAT_SFN_DISPLAY_LOWER
1311                                         | VFAT_SFN_CREATE_WIN95;
1312                         break;
1313                 case Opt_shortname_win95:
1314                         opts->shortname = VFAT_SFN_DISPLAY_WIN95
1315                                         | VFAT_SFN_CREATE_WIN95;
1316                         break;
1317                 case Opt_shortname_winnt:
1318                         opts->shortname = VFAT_SFN_DISPLAY_WINNT
1319                                         | VFAT_SFN_CREATE_WINNT;
1320                         break;
1321                 case Opt_shortname_mixed:
1322                         opts->shortname = VFAT_SFN_DISPLAY_WINNT
1323                                         | VFAT_SFN_CREATE_WIN95;
1324                         break;
1325                 case Opt_utf8_no:               /* 0 or no or false */
1326                         opts->utf8 = 0;
1327                         break;
1328                 case Opt_utf8_yes:              /* empty or 1 or yes or true */
1329                         opts->utf8 = 1;
1330                         break;
1331                 case Opt_uni_xl_no:             /* 0 or no or false */
1332                         opts->unicode_xlate = 0;
1333                         break;
1334                 case Opt_uni_xl_yes:            /* empty or 1 or yes or true */
1335                         opts->unicode_xlate = 1;
1336                         break;
1337                 case Opt_nonumtail_no:          /* 0 or no or false */
1338                         opts->numtail = 1;      /* negated option */
1339                         break;
1340                 case Opt_nonumtail_yes:         /* empty or 1 or yes or true */
1341                         opts->numtail = 0;      /* negated option */
1342                         break;
1343                 case Opt_rodir:
1344                         opts->rodir = 1;
1345                         break;
1346                 case Opt_discard:
1347                         opts->discard = 1;
1348                         break;
1349
1350                 /* obsolete mount options */
1351                 case Opt_obsolete:
1352                         fat_msg(sb, KERN_INFO, "\"%s\" option is obsolete, "
1353                                "not supported now", p);
1354                         break;
1355                 /* unknown option */
1356                 default:
1357                         if (!silent) {
1358                                 fat_msg(sb, KERN_ERR,
1359                                        "Unrecognized mount option \"%s\" "
1360                                        "or missing value", p);
1361                         }
1362                         return -EINVAL;
1363                 }
1364         }
1365
1366 out:
1367         /* UTF-8 doesn't provide FAT semantics */
1368         if (!strcmp(opts->iocharset, "utf8")) {
1369                 fat_msg(sb, KERN_WARNING, "utf8 is not a recommended IO charset"
1370                        " for FAT filesystems, filesystem will be "
1371                        "case sensitive!");
1372         }
1373
1374         /* If user doesn't specify allow_utime, it's initialized from dmask. */
1375         if (opts->allow_utime == (unsigned short)-1)
1376                 opts->allow_utime = ~opts->fs_dmask & (S_IWGRP | S_IWOTH);
1377         if (opts->unicode_xlate)
1378                 opts->utf8 = 0;
1379         if (opts->nfs == FAT_NFS_NOSTALE_RO) {
1380                 sb->s_flags |= SB_RDONLY;
1381                 sb->s_export_op = &fat_export_ops_nostale;
1382         }
1383
1384         return 0;
1385 }
1386
1387 static int fat_read_root(struct inode *inode)
1388 {
1389         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
1390         int error;
1391
1392         MSDOS_I(inode)->i_pos = MSDOS_ROOT_INO;
1393         inode->i_uid = sbi->options.fs_uid;
1394         inode->i_gid = sbi->options.fs_gid;
1395         inode_inc_iversion(inode);
1396         inode->i_generation = 0;
1397         inode->i_mode = fat_make_mode(sbi, ATTR_DIR, S_IRWXUGO);
1398         inode->i_op = sbi->dir_ops;
1399         inode->i_fop = &fat_dir_operations;
1400         if (is_fat32(sbi)) {
1401                 MSDOS_I(inode)->i_start = sbi->root_cluster;
1402                 error = fat_calc_dir_size(inode);
1403                 if (error < 0)
1404                         return error;
1405         } else {
1406                 MSDOS_I(inode)->i_start = 0;
1407                 inode->i_size = sbi->dir_entries * sizeof(struct msdos_dir_entry);
1408         }
1409         inode->i_blocks = ((inode->i_size + (sbi->cluster_size - 1))
1410                            & ~((loff_t)sbi->cluster_size - 1)) >> 9;
1411         MSDOS_I(inode)->i_logstart = 0;
1412         MSDOS_I(inode)->mmu_private = inode->i_size;
1413
1414         fat_save_attrs(inode, ATTR_DIR);
1415         inode->i_mtime.tv_sec = inode->i_atime.tv_sec = inode->i_ctime.tv_sec = 0;
1416         inode->i_mtime.tv_nsec = inode->i_atime.tv_nsec = inode->i_ctime.tv_nsec = 0;
1417         set_nlink(inode, fat_subdirs(inode)+2);
1418
1419         return 0;
1420 }
1421
1422 static unsigned long calc_fat_clusters(struct super_block *sb)
1423 {
1424         struct msdos_sb_info *sbi = MSDOS_SB(sb);
1425
1426         /* Divide first to avoid overflow */
1427         if (!is_fat12(sbi)) {
1428                 unsigned long ent_per_sec = sb->s_blocksize * 8 / sbi->fat_bits;
1429                 return ent_per_sec * sbi->fat_length;
1430         }
1431
1432         return sbi->fat_length * sb->s_blocksize * 8 / sbi->fat_bits;
1433 }
1434
1435 static bool fat_bpb_is_zero(struct fat_boot_sector *b)
1436 {
1437         if (get_unaligned_le16(&b->sector_size))
1438                 return false;
1439         if (b->sec_per_clus)
1440                 return false;
1441         if (b->reserved)
1442                 return false;
1443         if (b->fats)
1444                 return false;
1445         if (get_unaligned_le16(&b->dir_entries))
1446                 return false;
1447         if (get_unaligned_le16(&b->sectors))
1448                 return false;
1449         if (b->media)
1450                 return false;
1451         if (b->fat_length)
1452                 return false;
1453         if (b->secs_track)
1454                 return false;
1455         if (b->heads)
1456                 return false;
1457         return true;
1458 }
1459
1460 static int fat_read_bpb(struct super_block *sb, struct fat_boot_sector *b,
1461         int silent, struct fat_bios_param_block *bpb)
1462 {
1463         int error = -EINVAL;
1464
1465         /* Read in BPB ... */
1466         memset(bpb, 0, sizeof(*bpb));
1467         bpb->fat_sector_size = get_unaligned_le16(&b->sector_size);
1468         bpb->fat_sec_per_clus = b->sec_per_clus;
1469         bpb->fat_reserved = le16_to_cpu(b->reserved);
1470         bpb->fat_fats = b->fats;
1471         bpb->fat_dir_entries = get_unaligned_le16(&b->dir_entries);
1472         bpb->fat_sectors = get_unaligned_le16(&b->sectors);
1473         bpb->fat_fat_length = le16_to_cpu(b->fat_length);
1474         bpb->fat_total_sect = le32_to_cpu(b->total_sect);
1475
1476         bpb->fat16_state = b->fat16.state;
1477         bpb->fat16_vol_id = get_unaligned_le32(b->fat16.vol_id);
1478
1479         bpb->fat32_length = le32_to_cpu(b->fat32.length);
1480         bpb->fat32_root_cluster = le32_to_cpu(b->fat32.root_cluster);
1481         bpb->fat32_info_sector = le16_to_cpu(b->fat32.info_sector);
1482         bpb->fat32_state = b->fat32.state;
1483         bpb->fat32_vol_id = get_unaligned_le32(b->fat32.vol_id);
1484
1485         /* Validate this looks like a FAT filesystem BPB */
1486         if (!bpb->fat_reserved) {
1487                 if (!silent)
1488                         fat_msg(sb, KERN_ERR,
1489                                 "bogus number of reserved sectors");
1490                 goto out;
1491         }
1492         if (!bpb->fat_fats) {
1493                 if (!silent)
1494                         fat_msg(sb, KERN_ERR, "bogus number of FAT structure");
1495                 goto out;
1496         }
1497
1498         /*
1499          * Earlier we checked here that b->secs_track and b->head are nonzero,
1500          * but it turns out valid FAT filesystems can have zero there.
1501          */
1502
1503         if (!fat_valid_media(b->media)) {
1504                 if (!silent)
1505                         fat_msg(sb, KERN_ERR, "invalid media value (0x%02x)",
1506                                 (unsigned)b->media);
1507                 goto out;
1508         }
1509
1510         if (!is_power_of_2(bpb->fat_sector_size)
1511             || (bpb->fat_sector_size < 512)
1512             || (bpb->fat_sector_size > 4096)) {
1513                 if (!silent)
1514                         fat_msg(sb, KERN_ERR, "bogus logical sector size %u",
1515                                (unsigned)bpb->fat_sector_size);
1516                 goto out;
1517         }
1518
1519         if (!is_power_of_2(bpb->fat_sec_per_clus)) {
1520                 if (!silent)
1521                         fat_msg(sb, KERN_ERR, "bogus sectors per cluster %u",
1522                                 (unsigned)bpb->fat_sec_per_clus);
1523                 goto out;
1524         }
1525
1526         if (bpb->fat_fat_length == 0 && bpb->fat32_length == 0) {
1527                 if (!silent)
1528                         fat_msg(sb, KERN_ERR, "bogus number of FAT sectors");
1529                 goto out;
1530         }
1531
1532         error = 0;
1533
1534 out:
1535         return error;
1536 }
1537
1538 static int fat_read_static_bpb(struct super_block *sb,
1539         struct fat_boot_sector *b, int silent,
1540         struct fat_bios_param_block *bpb)
1541 {
1542         static const char *notdos1x = "This doesn't look like a DOS 1.x volume";
1543         sector_t bd_sects = bdev_nr_sectors(sb->s_bdev);
1544         struct fat_floppy_defaults *fdefaults = NULL;
1545         int error = -EINVAL;
1546         unsigned i;
1547
1548         /* 16-bit DOS 1.x reliably wrote bootstrap short-jmp code */
1549         if (b->ignored[0] != 0xeb || b->ignored[2] != 0x90) {
1550                 if (!silent)
1551                         fat_msg(sb, KERN_ERR,
1552                                 "%s; no bootstrapping code", notdos1x);
1553                 goto out;
1554         }
1555
1556         /*
1557          * If any value in this region is non-zero, it isn't archaic
1558          * DOS.
1559          */
1560         if (!fat_bpb_is_zero(b)) {
1561                 if (!silent)
1562                         fat_msg(sb, KERN_ERR,
1563                                 "%s; DOS 2.x BPB is non-zero", notdos1x);
1564                 goto out;
1565         }
1566
1567         for (i = 0; i < ARRAY_SIZE(floppy_defaults); i++) {
1568                 if (floppy_defaults[i].nr_sectors == bd_sects) {
1569                         fdefaults = &floppy_defaults[i];
1570                         break;
1571                 }
1572         }
1573
1574         if (fdefaults == NULL) {
1575                 if (!silent)
1576                         fat_msg(sb, KERN_WARNING,
1577                                 "This looks like a DOS 1.x volume, but isn't a recognized floppy size (%llu sectors)",
1578                                 (u64)bd_sects);
1579                 goto out;
1580         }
1581
1582         if (!silent)
1583                 fat_msg(sb, KERN_INFO,
1584                         "This looks like a DOS 1.x volume; assuming default BPB values");
1585
1586         memset(bpb, 0, sizeof(*bpb));
1587         bpb->fat_sector_size = SECTOR_SIZE;
1588         bpb->fat_sec_per_clus = fdefaults->sec_per_clus;
1589         bpb->fat_reserved = 1;
1590         bpb->fat_fats = 2;
1591         bpb->fat_dir_entries = fdefaults->dir_entries;
1592         bpb->fat_sectors = fdefaults->nr_sectors;
1593         bpb->fat_fat_length = fdefaults->fat_length;
1594
1595         error = 0;
1596
1597 out:
1598         return error;
1599 }
1600
1601 /*
1602  * Read the super block of an MS-DOS FS.
1603  */
1604 int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat,
1605                    void (*setup)(struct super_block *))
1606 {
1607         struct inode *root_inode = NULL, *fat_inode = NULL;
1608         struct inode *fsinfo_inode = NULL;
1609         struct buffer_head *bh;
1610         struct fat_bios_param_block bpb;
1611         struct msdos_sb_info *sbi;
1612         u16 logical_sector_size;
1613         u32 total_sectors, total_clusters, fat_clusters, rootdir_sectors;
1614         int debug;
1615         long error;
1616         char buf[50];
1617         struct timespec64 ts;
1618
1619         /*
1620          * GFP_KERNEL is ok here, because while we do hold the
1621          * superblock lock, memory pressure can't call back into
1622          * the filesystem, since we're only just about to mount
1623          * it and have no inodes etc active!
1624          */
1625         sbi = kzalloc(sizeof(struct msdos_sb_info), GFP_KERNEL);
1626         if (!sbi)
1627                 return -ENOMEM;
1628         sb->s_fs_info = sbi;
1629
1630         sb->s_flags |= SB_NODIRATIME;
1631         sb->s_magic = MSDOS_SUPER_MAGIC;
1632         sb->s_op = &fat_sops;
1633         sb->s_export_op = &fat_export_ops;
1634         /*
1635          * fat timestamps are complex and truncated by fat itself, so
1636          * we set 1 here to be fast
1637          */
1638         sb->s_time_gran = 1;
1639         mutex_init(&sbi->nfs_build_inode_lock);
1640         ratelimit_state_init(&sbi->ratelimit, DEFAULT_RATELIMIT_INTERVAL,
1641                              DEFAULT_RATELIMIT_BURST);
1642
1643         error = parse_options(sb, data, isvfat, silent, &debug, &sbi->options);
1644         if (error)
1645                 goto out_fail;
1646
1647         setup(sb); /* flavour-specific stuff that needs options */
1648
1649         error = -EIO;
1650         sb_min_blocksize(sb, 512);
1651         bh = sb_bread(sb, 0);
1652         if (bh == NULL) {
1653                 fat_msg(sb, KERN_ERR, "unable to read boot sector");
1654                 goto out_fail;
1655         }
1656
1657         error = fat_read_bpb(sb, (struct fat_boot_sector *)bh->b_data, silent,
1658                 &bpb);
1659         if (error == -EINVAL && sbi->options.dos1xfloppy)
1660                 error = fat_read_static_bpb(sb,
1661                         (struct fat_boot_sector *)bh->b_data, silent, &bpb);
1662         brelse(bh);
1663
1664         if (error == -EINVAL)
1665                 goto out_invalid;
1666         else if (error)
1667                 goto out_fail;
1668
1669         logical_sector_size = bpb.fat_sector_size;
1670         sbi->sec_per_clus = bpb.fat_sec_per_clus;
1671
1672         error = -EIO;
1673         if (logical_sector_size < sb->s_blocksize) {
1674                 fat_msg(sb, KERN_ERR, "logical sector size too small for device"
1675                        " (logical sector size = %u)", logical_sector_size);
1676                 goto out_fail;
1677         }
1678
1679         if (logical_sector_size > sb->s_blocksize) {
1680                 struct buffer_head *bh_resize;
1681
1682                 if (!sb_set_blocksize(sb, logical_sector_size)) {
1683                         fat_msg(sb, KERN_ERR, "unable to set blocksize %u",
1684                                logical_sector_size);
1685                         goto out_fail;
1686                 }
1687
1688                 /* Verify that the larger boot sector is fully readable */
1689                 bh_resize = sb_bread(sb, 0);
1690                 if (bh_resize == NULL) {
1691                         fat_msg(sb, KERN_ERR, "unable to read boot sector"
1692                                " (logical sector size = %lu)",
1693                                sb->s_blocksize);
1694                         goto out_fail;
1695                 }
1696                 brelse(bh_resize);
1697         }
1698
1699         mutex_init(&sbi->s_lock);
1700         sbi->cluster_size = sb->s_blocksize * sbi->sec_per_clus;
1701         sbi->cluster_bits = ffs(sbi->cluster_size) - 1;
1702         sbi->fats = bpb.fat_fats;
1703         sbi->fat_bits = 0;              /* Don't know yet */
1704         sbi->fat_start = bpb.fat_reserved;
1705         sbi->fat_length = bpb.fat_fat_length;
1706         sbi->root_cluster = 0;
1707         sbi->free_clusters = -1;        /* Don't know yet */
1708         sbi->free_clus_valid = 0;
1709         sbi->prev_free = FAT_START_ENT;
1710         sb->s_maxbytes = 0xffffffff;
1711         fat_time_fat2unix(sbi, &ts, 0, cpu_to_le16(FAT_DATE_MIN), 0);
1712         sb->s_time_min = ts.tv_sec;
1713
1714         fat_time_fat2unix(sbi, &ts, cpu_to_le16(FAT_TIME_MAX),
1715                           cpu_to_le16(FAT_DATE_MAX), 0);
1716         sb->s_time_max = ts.tv_sec;
1717
1718         if (!sbi->fat_length && bpb.fat32_length) {
1719                 struct fat_boot_fsinfo *fsinfo;
1720                 struct buffer_head *fsinfo_bh;
1721
1722                 /* Must be FAT32 */
1723                 sbi->fat_bits = 32;
1724                 sbi->fat_length = bpb.fat32_length;
1725                 sbi->root_cluster = bpb.fat32_root_cluster;
1726
1727                 /* MC - if info_sector is 0, don't multiply by 0 */
1728                 sbi->fsinfo_sector = bpb.fat32_info_sector;
1729                 if (sbi->fsinfo_sector == 0)
1730                         sbi->fsinfo_sector = 1;
1731
1732                 fsinfo_bh = sb_bread(sb, sbi->fsinfo_sector);
1733                 if (fsinfo_bh == NULL) {
1734                         fat_msg(sb, KERN_ERR, "bread failed, FSINFO block"
1735                                " (sector = %lu)", sbi->fsinfo_sector);
1736                         goto out_fail;
1737                 }
1738
1739                 fsinfo = (struct fat_boot_fsinfo *)fsinfo_bh->b_data;
1740                 if (!IS_FSINFO(fsinfo)) {
1741                         fat_msg(sb, KERN_WARNING, "Invalid FSINFO signature: "
1742                                "0x%08x, 0x%08x (sector = %lu)",
1743                                le32_to_cpu(fsinfo->signature1),
1744                                le32_to_cpu(fsinfo->signature2),
1745                                sbi->fsinfo_sector);
1746                 } else {
1747                         if (sbi->options.usefree)
1748                                 sbi->free_clus_valid = 1;
1749                         sbi->free_clusters = le32_to_cpu(fsinfo->free_clusters);
1750                         sbi->prev_free = le32_to_cpu(fsinfo->next_cluster);
1751                 }
1752
1753                 brelse(fsinfo_bh);
1754         }
1755
1756         /* interpret volume ID as a little endian 32 bit integer */
1757         if (is_fat32(sbi))
1758                 sbi->vol_id = bpb.fat32_vol_id;
1759         else /* fat 16 or 12 */
1760                 sbi->vol_id = bpb.fat16_vol_id;
1761
1762         sbi->dir_per_block = sb->s_blocksize / sizeof(struct msdos_dir_entry);
1763         sbi->dir_per_block_bits = ffs(sbi->dir_per_block) - 1;
1764
1765         sbi->dir_start = sbi->fat_start + sbi->fats * sbi->fat_length;
1766         sbi->dir_entries = bpb.fat_dir_entries;
1767         if (sbi->dir_entries & (sbi->dir_per_block - 1)) {
1768                 if (!silent)
1769                         fat_msg(sb, KERN_ERR, "bogus number of directory entries"
1770                                " (%u)", sbi->dir_entries);
1771                 goto out_invalid;
1772         }
1773
1774         rootdir_sectors = sbi->dir_entries
1775                 * sizeof(struct msdos_dir_entry) / sb->s_blocksize;
1776         sbi->data_start = sbi->dir_start + rootdir_sectors;
1777         total_sectors = bpb.fat_sectors;
1778         if (total_sectors == 0)
1779                 total_sectors = bpb.fat_total_sect;
1780
1781         total_clusters = (total_sectors - sbi->data_start) / sbi->sec_per_clus;
1782
1783         if (!is_fat32(sbi))
1784                 sbi->fat_bits = (total_clusters > MAX_FAT12) ? 16 : 12;
1785
1786         /* some OSes set FAT_STATE_DIRTY and clean it on unmount. */
1787         if (is_fat32(sbi))
1788                 sbi->dirty = bpb.fat32_state & FAT_STATE_DIRTY;
1789         else /* fat 16 or 12 */
1790                 sbi->dirty = bpb.fat16_state & FAT_STATE_DIRTY;
1791
1792         /* check that FAT table does not overflow */
1793         fat_clusters = calc_fat_clusters(sb);
1794         total_clusters = min(total_clusters, fat_clusters - FAT_START_ENT);
1795         if (total_clusters > max_fat(sb)) {
1796                 if (!silent)
1797                         fat_msg(sb, KERN_ERR, "count of clusters too big (%u)",
1798                                total_clusters);
1799                 goto out_invalid;
1800         }
1801
1802         sbi->max_cluster = total_clusters + FAT_START_ENT;
1803         /* check the free_clusters, it's not necessarily correct */
1804         if (sbi->free_clusters != -1 && sbi->free_clusters > total_clusters)
1805                 sbi->free_clusters = -1;
1806         /* check the prev_free, it's not necessarily correct */
1807         sbi->prev_free %= sbi->max_cluster;
1808         if (sbi->prev_free < FAT_START_ENT)
1809                 sbi->prev_free = FAT_START_ENT;
1810
1811         /* set up enough so that it can read an inode */
1812         fat_hash_init(sb);
1813         dir_hash_init(sb);
1814         fat_ent_access_init(sb);
1815
1816         /*
1817          * The low byte of the first FAT entry must have the same value as
1818          * the media field of the boot sector. But in real world, too many
1819          * devices are writing wrong values. So, removed that validity check.
1820          *
1821          * The removed check compared the first FAT entry to a value dependent
1822          * on the media field like this:
1823          * == (0x0F00 | media), for FAT12
1824          * == (0XFF00 | media), for FAT16
1825          * == (0x0FFFFF | media), for FAT32
1826          */
1827
1828         error = -EINVAL;
1829         sprintf(buf, "cp%d", sbi->options.codepage);
1830         sbi->nls_disk = load_nls(buf);
1831         if (!sbi->nls_disk) {
1832                 fat_msg(sb, KERN_ERR, "codepage %s not found", buf);
1833                 goto out_fail;
1834         }
1835
1836         /* FIXME: utf8 is using iocharset for upper/lower conversion */
1837         if (sbi->options.isvfat) {
1838                 sbi->nls_io = load_nls(sbi->options.iocharset);
1839                 if (!sbi->nls_io) {
1840                         fat_msg(sb, KERN_ERR, "IO charset %s not found",
1841                                sbi->options.iocharset);
1842                         goto out_fail;
1843                 }
1844         }
1845
1846         error = -ENOMEM;
1847         fat_inode = new_inode(sb);
1848         if (!fat_inode)
1849                 goto out_fail;
1850         sbi->fat_inode = fat_inode;
1851
1852         fsinfo_inode = new_inode(sb);
1853         if (!fsinfo_inode)
1854                 goto out_fail;
1855         fsinfo_inode->i_ino = MSDOS_FSINFO_INO;
1856         sbi->fsinfo_inode = fsinfo_inode;
1857         insert_inode_hash(fsinfo_inode);
1858
1859         root_inode = new_inode(sb);
1860         if (!root_inode)
1861                 goto out_fail;
1862         root_inode->i_ino = MSDOS_ROOT_INO;
1863         inode_set_iversion(root_inode, 1);
1864         error = fat_read_root(root_inode);
1865         if (error < 0) {
1866                 iput(root_inode);
1867                 goto out_fail;
1868         }
1869         error = -ENOMEM;
1870         insert_inode_hash(root_inode);
1871         fat_attach(root_inode, 0);
1872         sb->s_root = d_make_root(root_inode);
1873         if (!sb->s_root) {
1874                 fat_msg(sb, KERN_ERR, "get root inode failed");
1875                 goto out_fail;
1876         }
1877
1878         if (sbi->options.discard && !bdev_max_discard_sectors(sb->s_bdev))
1879                 fat_msg(sb, KERN_WARNING,
1880                         "mounting with \"discard\" option, but the device does not support discard");
1881
1882         fat_set_state(sb, 1, 0);
1883         return 0;
1884
1885 out_invalid:
1886         error = -EINVAL;
1887         if (!silent)
1888                 fat_msg(sb, KERN_INFO, "Can't find a valid FAT filesystem");
1889
1890 out_fail:
1891         iput(fsinfo_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                 ret = sync_blockdev_nowait(sb->s_bdev);
1943         return ret;
1944 }
1945 EXPORT_SYMBOL_GPL(fat_flush_inodes);
1946
1947 static int __init init_fat_fs(void)
1948 {
1949         int err;
1950
1951         err = fat_cache_init();
1952         if (err)
1953                 return err;
1954
1955         err = fat_init_inodecache();
1956         if (err)
1957                 goto failed;
1958
1959         return 0;
1960
1961 failed:
1962         fat_cache_destroy();
1963         return err;
1964 }
1965
1966 static void __exit exit_fat_fs(void)
1967 {
1968         fat_cache_destroy();
1969         fat_destroy_inodecache();
1970 }
1971
1972 module_init(init_fat_fs)
1973 module_exit(exit_fat_fs)
1974
1975 MODULE_LICENSE("GPL");