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 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, unsigned flags,
 230                         struct page **pagep, void **fsdata)
 231 {
 232         int err;
 233
 234         *pagep = NULL;
 235         err = cont_write_begin(file, mapping, pos, len, flags,
 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         .set_page_dirty = __set_page_dirty_buffers,
 346         .readpage       = fat_readpage,
 347         .readahead      = fat_readahead,
 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 = alloc_inode_sb(sb, 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 = u64_to_fsid(id);
 841         buf->f_namelen =
 842                 (sbi->options.isvfat ? FAT_LFN_LEN : 12) * NLS_MAX_CHARSET_SIZE;
 843
 844         return 0;
 845 }
 846
 847 static int __fat_write_inode(struct inode *inode, int wait)
 848 {
 849         struct super_block *sb = inode->i_sb;
 850         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 851         struct buffer_head *bh;
 852         struct msdos_dir_entry *raw_entry;
 853         loff_t i_pos;
 854         sector_t blocknr;
 855         int err, offset;
 856
 857         if (inode->i_ino == MSDOS_ROOT_INO)
 858                 return 0;
 859
 860 retry:
 861         i_pos = fat_i_pos_read(sbi, inode);
 862         if (!i_pos)
 863                 return 0;
 864
 865         fat_get_blknr_offset(sbi, i_pos, &blocknr, &offset);
 866         bh = sb_bread(sb, blocknr);
 867         if (!bh) {
 868                 fat_msg(sb, KERN_ERR, "unable to read inode block "
 869                        "for updating (i_pos %lld)", i_pos);
 870                 return -EIO;
 871         }
 872         spin_lock(&sbi->inode_hash_lock);
 873         if (i_pos != MSDOS_I(inode)->i_pos) {
 874                 spin_unlock(&sbi->inode_hash_lock);
 875                 brelse(bh);
 876                 goto retry;
 877         }
 878
 879         raw_entry = &((struct msdos_dir_entry *) (bh->b_data))[offset];
 880         if (S_ISDIR(inode->i_mode))
 881                 raw_entry->size = 0;
 882         else
 883                 raw_entry->size = cpu_to_le32(inode->i_size);
 884         raw_entry->attr = fat_make_attrs(inode);
 885         fat_set_start(raw_entry, MSDOS_I(inode)->i_logstart);
 886         fat_time_unix2fat(sbi, &inode->i_mtime, &raw_entry->time,
 887                           &raw_entry->date, NULL);
 888         if (sbi->options.isvfat) {
 889                 __le16 atime;
 890                 fat_time_unix2fat(sbi, &inode->i_ctime, &raw_entry->ctime,
 891                                   &raw_entry->cdate, &raw_entry->ctime_cs);
 892                 fat_time_unix2fat(sbi, &inode->i_atime, &atime,
 893                                   &raw_entry->adate, NULL);
 894         }
 895         spin_unlock(&sbi->inode_hash_lock);
 896         mark_buffer_dirty(bh);
 897         err = 0;
 898         if (wait)
 899                 err = sync_dirty_buffer(bh);
 900         brelse(bh);
 901         return err;
 902 }
 903
 904 static int fat_write_inode(struct inode *inode, struct writeback_control *wbc)
 905 {
 906         int err;
 907
 908         if (inode->i_ino == MSDOS_FSINFO_INO) {
 909                 struct super_block *sb = inode->i_sb;
 910
 911                 mutex_lock(&MSDOS_SB(sb)->s_lock);
 912                 err = fat_clusters_flush(sb);
 913                 mutex_unlock(&MSDOS_SB(sb)->s_lock);
 914         } else
 915                 err = __fat_write_inode(inode, wbc->sync_mode == WB_SYNC_ALL);
 916
 917         return err;
 918 }
 919
 920 int fat_sync_inode(struct inode *inode)
 921 {
 922         return __fat_write_inode(inode, 1);
 923 }
 924
 925 EXPORT_SYMBOL_GPL(fat_sync_inode);
 926
 927 static int fat_show_options(struct seq_file *m, struct dentry *root);
 928 static const struct super_operations fat_sops = {
 929         .alloc_inode    = fat_alloc_inode,
 930         .free_inode     = fat_free_inode,
 931         .write_inode    = fat_write_inode,
 932         .evict_inode    = fat_evict_inode,
 933         .put_super      = fat_put_super,
 934         .statfs         = fat_statfs,
 935         .remount_fs     = fat_remount,
 936
 937         .show_options   = fat_show_options,
 938 };
 939
 940 static int fat_show_options(struct seq_file *m, struct dentry *root)
 941 {
 942         struct msdos_sb_info *sbi = MSDOS_SB(root->d_sb);
 943         struct fat_mount_options *opts = &sbi->options;
 944         int isvfat = opts->isvfat;
 945
 946         if (!uid_eq(opts->fs_uid, GLOBAL_ROOT_UID))
 947                 seq_printf(m, ",uid=%u",
 948                                 from_kuid_munged(&init_user_ns, opts->fs_uid));
 949         if (!gid_eq(opts->fs_gid, GLOBAL_ROOT_GID))
 950                 seq_printf(m, ",gid=%u",
 951                                 from_kgid_munged(&init_user_ns, opts->fs_gid));
 952         seq_printf(m, ",fmask=%04o", opts->fs_fmask);
 953         seq_printf(m, ",dmask=%04o", opts->fs_dmask);
 954         if (opts->allow_utime)
 955                 seq_printf(m, ",allow_utime=%04o", opts->allow_utime);
 956         if (sbi->nls_disk)
 957                 /* strip "cp" prefix from displayed option */
 958                 seq_printf(m, ",codepage=%s", &sbi->nls_disk->charset[2]);
 959         if (isvfat) {
 960                 if (sbi->nls_io)
 961                         seq_printf(m, ",iocharset=%s", sbi->nls_io->charset);
 962
 963                 switch (opts->shortname) {
 964                 case VFAT_SFN_DISPLAY_WIN95 | VFAT_SFN_CREATE_WIN95:
 965                         seq_puts(m, ",shortname=win95");
 966                         break;
 967                 case VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WINNT:
 968                         seq_puts(m, ",shortname=winnt");
 969                         break;
 970                 case VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WIN95:
 971                         seq_puts(m, ",shortname=mixed");
 972                         break;
 973                 case VFAT_SFN_DISPLAY_LOWER | VFAT_SFN_CREATE_WIN95:
 974                         seq_puts(m, ",shortname=lower");
 975                         break;
 976                 default:
 977                         seq_puts(m, ",shortname=unknown");
 978                         break;
 979                 }
 980         }
 981         if (opts->name_check != 'n')
 982                 seq_printf(m, ",check=%c", opts->name_check);
 983         if (opts->usefree)
 984                 seq_puts(m, ",usefree");
 985         if (opts->quiet)
 986                 seq_puts(m, ",quiet");
 987         if (opts->showexec)
 988                 seq_puts(m, ",showexec");
 989         if (opts->sys_immutable)
 990                 seq_puts(m, ",sys_immutable");
 991         if (!isvfat) {
 992                 if (opts->dotsOK)
 993                         seq_puts(m, ",dotsOK=yes");
 994                 if (opts->nocase)
 995                         seq_puts(m, ",nocase");
 996         } else {
 997                 if (opts->utf8)
 998                         seq_puts(m, ",utf8");
 999                 if (opts->unicode_xlate)
1000                         seq_puts(m, ",uni_xlate");
1001                 if (!opts->numtail)
1002                         seq_puts(m, ",nonumtail");
1003                 if (opts->rodir)
1004                         seq_puts(m, ",rodir");
1005         }
1006         if (opts->flush)
1007                 seq_puts(m, ",flush");
1008         if (opts->tz_set) {
1009                 if (opts->time_offset)
1010                         seq_printf(m, ",time_offset=%d", opts->time_offset);
1011                 else
1012                         seq_puts(m, ",tz=UTC");
1013         }
1014         if (opts->errors == FAT_ERRORS_CONT)
1015                 seq_puts(m, ",errors=continue");
1016         else if (opts->errors == FAT_ERRORS_PANIC)
1017                 seq_puts(m, ",errors=panic");
1018         else
1019                 seq_puts(m, ",errors=remount-ro");
1020         if (opts->nfs == FAT_NFS_NOSTALE_RO)
1021                 seq_puts(m, ",nfs=nostale_ro");
1022         else if (opts->nfs)
1023                 seq_puts(m, ",nfs=stale_rw");
1024         if (opts->discard)
1025                 seq_puts(m, ",discard");
1026         if (opts->dos1xfloppy)
1027                 seq_puts(m, ",dos1xfloppy");
1028
1029         return 0;
1030 }
1031
1032 enum {
1033         Opt_check_n, Opt_check_r, Opt_check_s, Opt_uid, Opt_gid,
1034         Opt_umask, Opt_dmask, Opt_fmask, Opt_allow_utime, Opt_codepage,
1035         Opt_usefree, Opt_nocase, Opt_quiet, Opt_showexec, Opt_debug,
1036         Opt_immutable, Opt_dots, Opt_nodots,
1037         Opt_charset, Opt_shortname_lower, Opt_shortname_win95,
1038         Opt_shortname_winnt, Opt_shortname_mixed, Opt_utf8_no, Opt_utf8_yes,
1039         Opt_uni_xl_no, Opt_uni_xl_yes, Opt_nonumtail_no, Opt_nonumtail_yes,
1040         Opt_obsolete, Opt_flush, Opt_tz_utc, Opt_rodir, Opt_err_cont,
1041         Opt_err_panic, Opt_err_ro, Opt_discard, Opt_nfs, Opt_time_offset,
1042         Opt_nfs_stale_rw, Opt_nfs_nostale_ro, Opt_err, Opt_dos1xfloppy,
1043 };
1044
1045 static const match_table_t fat_tokens = {
1046         {Opt_check_r, "check=relaxed"},
1047         {Opt_check_s, "check=strict"},
1048         {Opt_check_n, "check=normal"},
1049         {Opt_check_r, "check=r"},
1050         {Opt_check_s, "check=s"},
1051         {Opt_check_n, "check=n"},
1052         {Opt_uid, "uid=%u"},
1053         {Opt_gid, "gid=%u"},
1054         {Opt_umask, "umask=%o"},
1055         {Opt_dmask, "dmask=%o"},
1056         {Opt_fmask, "fmask=%o"},
1057         {Opt_allow_utime, "allow_utime=%o"},
1058         {Opt_codepage, "codepage=%u"},
1059         {Opt_usefree, "usefree"},
1060         {Opt_nocase, "nocase"},
1061         {Opt_quiet, "quiet"},
1062         {Opt_showexec, "showexec"},
1063         {Opt_debug, "debug"},
1064         {Opt_immutable, "sys_immutable"},
1065         {Opt_flush, "flush"},
1066         {Opt_tz_utc, "tz=UTC"},
1067         {Opt_time_offset, "time_offset=%d"},
1068         {Opt_err_cont, "errors=continue"},
1069         {Opt_err_panic, "errors=panic"},
1070         {Opt_err_ro, "errors=remount-ro"},
1071         {Opt_discard, "discard"},
1072         {Opt_nfs_stale_rw, "nfs"},
1073         {Opt_nfs_stale_rw, "nfs=stale_rw"},
1074         {Opt_nfs_nostale_ro, "nfs=nostale_ro"},
1075         {Opt_dos1xfloppy, "dos1xfloppy"},
1076         {Opt_obsolete, "conv=binary"},
1077         {Opt_obsolete, "conv=text"},
1078         {Opt_obsolete, "conv=auto"},
1079         {Opt_obsolete, "conv=b"},
1080         {Opt_obsolete, "conv=t"},
1081         {Opt_obsolete, "conv=a"},
1082         {Opt_obsolete, "fat=%u"},
1083         {Opt_obsolete, "blocksize=%u"},
1084         {Opt_obsolete, "cvf_format=%20s"},
1085         {Opt_obsolete, "cvf_options=%100s"},
1086         {Opt_obsolete, "posix"},
1087         {Opt_err, NULL},
1088 };
1089 static const match_table_t msdos_tokens = {
1090         {Opt_nodots, "nodots"},
1091         {Opt_nodots, "dotsOK=no"},
1092         {Opt_dots, "dots"},
1093         {Opt_dots, "dotsOK=yes"},
1094         {Opt_err, NULL}
1095 };
1096 static const match_table_t vfat_tokens = {
1097         {Opt_charset, "iocharset=%s"},
1098         {Opt_shortname_lower, "shortname=lower"},
1099         {Opt_shortname_win95, "shortname=win95"},
1100         {Opt_shortname_winnt, "shortname=winnt"},
1101         {Opt_shortname_mixed, "shortname=mixed"},
1102         {Opt_utf8_no, "utf8=0"},                /* 0 or no or false */
1103         {Opt_utf8_no, "utf8=no"},
1104         {Opt_utf8_no, "utf8=false"},
1105         {Opt_utf8_yes, "utf8=1"},               /* empty or 1 or yes or true */
1106         {Opt_utf8_yes, "utf8=yes"},
1107         {Opt_utf8_yes, "utf8=true"},
1108         {Opt_utf8_yes, "utf8"},
1109         {Opt_uni_xl_no, "uni_xlate=0"},         /* 0 or no or false */
1110         {Opt_uni_xl_no, "uni_xlate=no"},
1111         {Opt_uni_xl_no, "uni_xlate=false"},
1112         {Opt_uni_xl_yes, "uni_xlate=1"},        /* empty or 1 or yes or true */
1113         {Opt_uni_xl_yes, "uni_xlate=yes"},
1114         {Opt_uni_xl_yes, "uni_xlate=true"},
1115         {Opt_uni_xl_yes, "uni_xlate"},
1116         {Opt_nonumtail_no, "nonumtail=0"},      /* 0 or no or false */
1117         {Opt_nonumtail_no, "nonumtail=no"},
1118         {Opt_nonumtail_no, "nonumtail=false"},
1119         {Opt_nonumtail_yes, "nonumtail=1"},     /* empty or 1 or yes or true */
1120         {Opt_nonumtail_yes, "nonumtail=yes"},
1121         {Opt_nonumtail_yes, "nonumtail=true"},
1122         {Opt_nonumtail_yes, "nonumtail"},
1123         {Opt_rodir, "rodir"},
1124         {Opt_err, NULL}
1125 };
1126
1127 static int parse_options(struct super_block *sb, char *options, int is_vfat,
1128                          int silent, int *debug, struct fat_mount_options *opts)
1129 {
1130         char *p;
1131         substring_t args[MAX_OPT_ARGS];
1132         int option;
1133         char *iocharset;
1134
1135         opts->isvfat = is_vfat;
1136
1137         opts->fs_uid = current_uid();
1138         opts->fs_gid = current_gid();
1139         opts->fs_fmask = opts->fs_dmask = current_umask();
1140         opts->allow_utime = -1;
1141         opts->codepage = fat_default_codepage;
1142         fat_reset_iocharset(opts);
1143         if (is_vfat) {
1144                 opts->shortname = VFAT_SFN_DISPLAY_WINNT|VFAT_SFN_CREATE_WIN95;
1145                 opts->rodir = 0;
1146         } else {
1147                 opts->shortname = 0;
1148                 opts->rodir = 1;
1149         }
1150         opts->name_check = 'n';
1151         opts->quiet = opts->showexec = opts->sys_immutable = opts->dotsOK =  0;
1152         opts->unicode_xlate = 0;
1153         opts->numtail = 1;
1154         opts->usefree = opts->nocase = 0;
1155         opts->tz_set = 0;
1156         opts->nfs = 0;
1157         opts->errors = FAT_ERRORS_RO;
1158         *debug = 0;
1159
1160         opts->utf8 = IS_ENABLED(CONFIG_FAT_DEFAULT_UTF8) && is_vfat;
1161
1162         if (!options)
1163                 goto out;
1164
1165         while ((p = strsep(&options, ",")) != NULL) {
1166                 int token;
1167                 if (!*p)
1168                         continue;
1169
1170                 token = match_token(p, fat_tokens, args);
1171                 if (token == Opt_err) {
1172                         if (is_vfat)
1173                                 token = match_token(p, vfat_tokens, args);
1174                         else
1175                                 token = match_token(p, msdos_tokens, args);
1176                 }
1177                 switch (token) {
1178                 case Opt_check_s:
1179                         opts->name_check = 's';
1180                         break;
1181                 case Opt_check_r:
1182                         opts->name_check = 'r';
1183                         break;
1184                 case Opt_check_n:
1185                         opts->name_check = 'n';
1186                         break;
1187                 case Opt_usefree:
1188                         opts->usefree = 1;
1189                         break;
1190                 case Opt_nocase:
1191                         if (!is_vfat)
1192                                 opts->nocase = 1;
1193                         else {
1194                                 /* for backward compatibility */
1195                                 opts->shortname = VFAT_SFN_DISPLAY_WIN95
1196                                         | VFAT_SFN_CREATE_WIN95;
1197                         }
1198                         break;
1199                 case Opt_quiet:
1200                         opts->quiet = 1;
1201                         break;
1202                 case Opt_showexec:
1203                         opts->showexec = 1;
1204                         break;
1205                 case Opt_debug:
1206                         *debug = 1;
1207                         break;
1208                 case Opt_immutable:
1209                         opts->sys_immutable = 1;
1210                         break;
1211                 case Opt_uid:
1212                         if (match_int(&args[0], &option))
1213                                 return -EINVAL;
1214                         opts->fs_uid = make_kuid(current_user_ns(), option);
1215                         if (!uid_valid(opts->fs_uid))
1216                                 return -EINVAL;
1217                         break;
1218                 case Opt_gid:
1219                         if (match_int(&args[0], &option))
1220                                 return -EINVAL;
1221                         opts->fs_gid = make_kgid(current_user_ns(), option);
1222                         if (!gid_valid(opts->fs_gid))
1223                                 return -EINVAL;
1224                         break;
1225                 case Opt_umask:
1226                         if (match_octal(&args[0], &option))
1227                                 return -EINVAL;
1228                         opts->fs_fmask = opts->fs_dmask = option;
1229                         break;
1230                 case Opt_dmask:
1231                         if (match_octal(&args[0], &option))
1232                                 return -EINVAL;
1233                         opts->fs_dmask = option;
1234                         break;
1235                 case Opt_fmask:
1236                         if (match_octal(&args[0], &option))
1237                                 return -EINVAL;
1238                         opts->fs_fmask = option;
1239                         break;
1240                 case Opt_allow_utime:
1241                         if (match_octal(&args[0], &option))
1242                                 return -EINVAL;
1243                         opts->allow_utime = option & (S_IWGRP | S_IWOTH);
1244                         break;
1245                 case Opt_codepage:
1246                         if (match_int(&args[0], &option))
1247                                 return -EINVAL;
1248                         opts->codepage = option;
1249                         break;
1250                 case Opt_flush:
1251                         opts->flush = 1;
1252                         break;
1253                 case Opt_time_offset:
1254                         if (match_int(&args[0], &option))
1255                                 return -EINVAL;
1256                         /*
1257                          * GMT+-12 zones may have DST corrections so at least
1258                          * 13 hours difference is needed. Make the limit 24
1259                          * just in case someone invents something unusual.
1260                          */
1261                         if (option < -24 * 60 || option > 24 * 60)
1262                                 return -EINVAL;
1263                         opts->tz_set = 1;
1264                         opts->time_offset = option;
1265                         break;
1266                 case Opt_tz_utc:
1267                         opts->tz_set = 1;
1268                         opts->time_offset = 0;
1269                         break;
1270                 case Opt_err_cont:
1271                         opts->errors = FAT_ERRORS_CONT;
1272                         break;
1273                 case Opt_err_panic:
1274                         opts->errors = FAT_ERRORS_PANIC;
1275                         break;
1276                 case Opt_err_ro:
1277                         opts->errors = FAT_ERRORS_RO;
1278                         break;
1279                 case Opt_nfs_stale_rw:
1280                         opts->nfs = FAT_NFS_STALE_RW;
1281                         break;
1282                 case Opt_nfs_nostale_ro:
1283                         opts->nfs = FAT_NFS_NOSTALE_RO;
1284                         break;
1285                 case Opt_dos1xfloppy:
1286                         opts->dos1xfloppy = 1;
1287                         break;
1288
1289                 /* msdos specific */
1290                 case Opt_dots:
1291                         opts->dotsOK = 1;
1292                         break;
1293                 case Opt_nodots:
1294                         opts->dotsOK = 0;
1295                         break;
1296
1297                 /* vfat specific */
1298                 case Opt_charset:
1299                         fat_reset_iocharset(opts);
1300                         iocharset = match_strdup(&args[0]);
1301                         if (!iocharset)
1302                                 return -ENOMEM;
1303                         opts->iocharset = iocharset;
1304                         break;
1305                 case Opt_shortname_lower:
1306                         opts->shortname = VFAT_SFN_DISPLAY_LOWER
1307                                         | VFAT_SFN_CREATE_WIN95;
1308                         break;
1309                 case Opt_shortname_win95:
1310                         opts->shortname = VFAT_SFN_DISPLAY_WIN95
1311                                         | VFAT_SFN_CREATE_WIN95;
1312                         break;
1313                 case Opt_shortname_winnt:
1314                         opts->shortname = VFAT_SFN_DISPLAY_WINNT
1315                                         | VFAT_SFN_CREATE_WINNT;
1316                         break;
1317                 case Opt_shortname_mixed:
1318                         opts->shortname = VFAT_SFN_DISPLAY_WINNT
1319                                         | VFAT_SFN_CREATE_WIN95;
1320                         break;
1321                 case Opt_utf8_no:               /* 0 or no or false */
1322                         opts->utf8 = 0;
1323                         break;
1324                 case Opt_utf8_yes:              /* empty or 1 or yes or true */
1325                         opts->utf8 = 1;
1326                         break;
1327                 case Opt_uni_xl_no:             /* 0 or no or false */
1328                         opts->unicode_xlate = 0;
1329                         break;
1330                 case Opt_uni_xl_yes:            /* empty or 1 or yes or true */
1331                         opts->unicode_xlate = 1;
1332                         break;
1333                 case Opt_nonumtail_no:          /* 0 or no or false */
1334                         opts->numtail = 1;      /* negated option */
1335                         break;
1336                 case Opt_nonumtail_yes:         /* empty or 1 or yes or true */
1337                         opts->numtail = 0;      /* negated option */
1338                         break;
1339                 case Opt_rodir:
1340                         opts->rodir = 1;
1341                         break;
1342                 case Opt_discard:
1343                         opts->discard = 1;
1344                         break;
1345
1346                 /* obsolete mount options */
1347                 case Opt_obsolete:
1348                         fat_msg(sb, KERN_INFO, "\"%s\" option is obsolete, "
1349                                "not supported now", p);
1350                         break;
1351                 /* unknown option */
1352                 default:
1353                         if (!silent) {
1354                                 fat_msg(sb, KERN_ERR,
1355                                        "Unrecognized mount option \"%s\" "
1356                                        "or missing value", p);
1357                         }
1358                         return -EINVAL;
1359                 }
1360         }
1361
1362 out:
1363         /* UTF-8 doesn't provide FAT semantics */
1364         if (!strcmp(opts->iocharset, "utf8")) {
1365                 fat_msg(sb, KERN_WARNING, "utf8 is not a recommended IO charset"
1366                        " for FAT filesystems, filesystem will be "
1367                        "case sensitive!");
1368         }
1369
1370         /* If user doesn't specify allow_utime, it's initialized from dmask. */
1371         if (opts->allow_utime == (unsigned short)-1)
1372                 opts->allow_utime = ~opts->fs_dmask & (S_IWGRP | S_IWOTH);
1373         if (opts->unicode_xlate)
1374                 opts->utf8 = 0;
1375         if (opts->nfs == FAT_NFS_NOSTALE_RO) {
1376                 sb->s_flags |= SB_RDONLY;
1377                 sb->s_export_op = &fat_export_ops_nostale;
1378         }
1379
1380         return 0;
1381 }
1382
1383 static int fat_read_root(struct inode *inode)
1384 {
1385         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
1386         int error;
1387
1388         MSDOS_I(inode)->i_pos = MSDOS_ROOT_INO;
1389         inode->i_uid = sbi->options.fs_uid;
1390         inode->i_gid = sbi->options.fs_gid;
1391         inode_inc_iversion(inode);
1392         inode->i_generation = 0;
1393         inode->i_mode = fat_make_mode(sbi, ATTR_DIR, S_IRWXUGO);
1394         inode->i_op = sbi->dir_ops;
1395         inode->i_fop = &fat_dir_operations;
1396         if (is_fat32(sbi)) {
1397                 MSDOS_I(inode)->i_start = sbi->root_cluster;
1398                 error = fat_calc_dir_size(inode);
1399                 if (error < 0)
1400                         return error;
1401         } else {
1402                 MSDOS_I(inode)->i_start = 0;
1403                 inode->i_size = sbi->dir_entries * sizeof(struct msdos_dir_entry);
1404         }
1405         inode->i_blocks = ((inode->i_size + (sbi->cluster_size - 1))
1406                            & ~((loff_t)sbi->cluster_size - 1)) >> 9;
1407         MSDOS_I(inode)->i_logstart = 0;
1408         MSDOS_I(inode)->mmu_private = inode->i_size;
1409
1410         fat_save_attrs(inode, ATTR_DIR);
1411         inode->i_mtime.tv_sec = inode->i_atime.tv_sec = inode->i_ctime.tv_sec = 0;
1412         inode->i_mtime.tv_nsec = inode->i_atime.tv_nsec = inode->i_ctime.tv_nsec = 0;
1413         set_nlink(inode, fat_subdirs(inode)+2);
1414
1415         return 0;
1416 }
1417
1418 static unsigned long calc_fat_clusters(struct super_block *sb)
1419 {
1420         struct msdos_sb_info *sbi = MSDOS_SB(sb);
1421
1422         /* Divide first to avoid overflow */
1423         if (!is_fat12(sbi)) {
1424                 unsigned long ent_per_sec = sb->s_blocksize * 8 / sbi->fat_bits;
1425                 return ent_per_sec * sbi->fat_length;
1426         }
1427
1428         return sbi->fat_length * sb->s_blocksize * 8 / sbi->fat_bits;
1429 }
1430
1431 static bool fat_bpb_is_zero(struct fat_boot_sector *b)
1432 {
1433         if (get_unaligned_le16(&b->sector_size))
1434                 return false;
1435         if (b->sec_per_clus)
1436                 return false;
1437         if (b->reserved)
1438                 return false;
1439         if (b->fats)
1440                 return false;
1441         if (get_unaligned_le16(&b->dir_entries))
1442                 return false;
1443         if (get_unaligned_le16(&b->sectors))
1444                 return false;
1445         if (b->media)
1446                 return false;
1447         if (b->fat_length)
1448                 return false;
1449         if (b->secs_track)
1450                 return false;
1451         if (b->heads)
1452                 return false;
1453         return true;
1454 }
1455
1456 static int fat_read_bpb(struct super_block *sb, struct fat_boot_sector *b,
1457         int silent, struct fat_bios_param_block *bpb)
1458 {
1459         int error = -EINVAL;
1460
1461         /* Read in BPB ... */
1462         memset(bpb, 0, sizeof(*bpb));
1463         bpb->fat_sector_size = get_unaligned_le16(&b->sector_size);
1464         bpb->fat_sec_per_clus = b->sec_per_clus;
1465         bpb->fat_reserved = le16_to_cpu(b->reserved);
1466         bpb->fat_fats = b->fats;
1467         bpb->fat_dir_entries = get_unaligned_le16(&b->dir_entries);
1468         bpb->fat_sectors = get_unaligned_le16(&b->sectors);
1469         bpb->fat_fat_length = le16_to_cpu(b->fat_length);
1470         bpb->fat_total_sect = le32_to_cpu(b->total_sect);
1471
1472         bpb->fat16_state = b->fat16.state;
1473         bpb->fat16_vol_id = get_unaligned_le32(b->fat16.vol_id);
1474
1475         bpb->fat32_length = le32_to_cpu(b->fat32.length);
1476         bpb->fat32_root_cluster = le32_to_cpu(b->fat32.root_cluster);
1477         bpb->fat32_info_sector = le16_to_cpu(b->fat32.info_sector);
1478         bpb->fat32_state = b->fat32.state;
1479         bpb->fat32_vol_id = get_unaligned_le32(b->fat32.vol_id);
1480
1481         /* Validate this looks like a FAT filesystem BPB */
1482         if (!bpb->fat_reserved) {
1483                 if (!silent)
1484                         fat_msg(sb, KERN_ERR,
1485                                 "bogus number of reserved sectors");
1486                 goto out;
1487         }
1488         if (!bpb->fat_fats) {
1489                 if (!silent)
1490                         fat_msg(sb, KERN_ERR, "bogus number of FAT structure");
1491                 goto out;
1492         }
1493
1494         /*
1495          * Earlier we checked here that b->secs_track and b->head are nonzero,
1496          * but it turns out valid FAT filesystems can have zero there.
1497          */
1498
1499         if (!fat_valid_media(b->media)) {
1500                 if (!silent)
1501                         fat_msg(sb, KERN_ERR, "invalid media value (0x%02x)",
1502                                 (unsigned)b->media);
1503                 goto out;
1504         }
1505
1506         if (!is_power_of_2(bpb->fat_sector_size)
1507             || (bpb->fat_sector_size < 512)
1508             || (bpb->fat_sector_size > 4096)) {
1509                 if (!silent)
1510                         fat_msg(sb, KERN_ERR, "bogus logical sector size %u",
1511                                (unsigned)bpb->fat_sector_size);
1512                 goto out;
1513         }
1514
1515         if (!is_power_of_2(bpb->fat_sec_per_clus)) {
1516                 if (!silent)
1517                         fat_msg(sb, KERN_ERR, "bogus sectors per cluster %u",
1518                                 (unsigned)bpb->fat_sec_per_clus);
1519                 goto out;
1520         }
1521
1522         if (bpb->fat_fat_length == 0 && bpb->fat32_length == 0) {
1523                 if (!silent)
1524                         fat_msg(sb, KERN_ERR, "bogus number of FAT sectors");
1525                 goto out;
1526         }
1527
1528         error = 0;
1529
1530 out:
1531         return error;
1532 }
1533
1534 static int fat_read_static_bpb(struct super_block *sb,
1535         struct fat_boot_sector *b, int silent,
1536         struct fat_bios_param_block *bpb)
1537 {
1538         static const char *notdos1x = "This doesn't look like a DOS 1.x volume";
1539         sector_t bd_sects = bdev_nr_sectors(sb->s_bdev);
1540         struct fat_floppy_defaults *fdefaults = NULL;
1541         int error = -EINVAL;
1542         unsigned i;
1543
1544         /* 16-bit DOS 1.x reliably wrote bootstrap short-jmp code */
1545         if (b->ignored[0] != 0xeb || b->ignored[2] != 0x90) {
1546                 if (!silent)
1547                         fat_msg(sb, KERN_ERR,
1548                                 "%s; no bootstrapping code", notdos1x);
1549                 goto out;
1550         }
1551
1552         /*
1553          * If any value in this region is non-zero, it isn't archaic
1554          * DOS.
1555          */
1556         if (!fat_bpb_is_zero(b)) {
1557                 if (!silent)
1558                         fat_msg(sb, KERN_ERR,
1559                                 "%s; DOS 2.x BPB is non-zero", notdos1x);
1560                 goto out;
1561         }
1562
1563         for (i = 0; i < ARRAY_SIZE(floppy_defaults); i++) {
1564                 if (floppy_defaults[i].nr_sectors == bd_sects) {
1565                         fdefaults = &floppy_defaults[i];
1566                         break;
1567                 }
1568         }
1569
1570         if (fdefaults == NULL) {
1571                 if (!silent)
1572                         fat_msg(sb, KERN_WARNING,
1573                                 "This looks like a DOS 1.x volume, but isn't a recognized floppy size (%llu sectors)",
1574                                 (u64)bd_sects);
1575                 goto out;
1576         }
1577
1578         if (!silent)
1579                 fat_msg(sb, KERN_INFO,
1580                         "This looks like a DOS 1.x volume; assuming default BPB values");
1581
1582         memset(bpb, 0, sizeof(*bpb));
1583         bpb->fat_sector_size = SECTOR_SIZE;
1584         bpb->fat_sec_per_clus = fdefaults->sec_per_clus;
1585         bpb->fat_reserved = 1;
1586         bpb->fat_fats = 2;
1587         bpb->fat_dir_entries = fdefaults->dir_entries;
1588         bpb->fat_sectors = fdefaults->nr_sectors;
1589         bpb->fat_fat_length = fdefaults->fat_length;
1590
1591         error = 0;
1592
1593 out:
1594         return error;
1595 }
1596
1597 /*
1598  * Read the super block of an MS-DOS FS.
1599  */
1600 int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat,
1601                    void (*setup)(struct super_block *))
1602 {
1603         struct inode *root_inode = NULL, *fat_inode = NULL;
1604         struct inode *fsinfo_inode = NULL;
1605         struct buffer_head *bh;
1606         struct fat_bios_param_block bpb;
1607         struct msdos_sb_info *sbi;
1608         u16 logical_sector_size;
1609         u32 total_sectors, total_clusters, fat_clusters, rootdir_sectors;
1610         int debug;
1611         long error;
1612         char buf[50];
1613         struct timespec64 ts;
1614
1615         /*
1616          * GFP_KERNEL is ok here, because while we do hold the
1617          * superblock lock, memory pressure can't call back into
1618          * the filesystem, since we're only just about to mount
1619          * it and have no inodes etc active!
1620          */
1621         sbi = kzalloc(sizeof(struct msdos_sb_info), GFP_KERNEL);
1622         if (!sbi)
1623                 return -ENOMEM;
1624         sb->s_fs_info = sbi;
1625
1626         sb->s_flags |= SB_NODIRATIME;
1627         sb->s_magic = MSDOS_SUPER_MAGIC;
1628         sb->s_op = &fat_sops;
1629         sb->s_export_op = &fat_export_ops;
1630         /*
1631          * fat timestamps are complex and truncated by fat itself, so
1632          * we set 1 here to be fast
1633          */
1634         sb->s_time_gran = 1;
1635         mutex_init(&sbi->nfs_build_inode_lock);
1636         ratelimit_state_init(&sbi->ratelimit, DEFAULT_RATELIMIT_INTERVAL,
1637                              DEFAULT_RATELIMIT_BURST);
1638
1639         error = parse_options(sb, data, isvfat, silent, &debug, &sbi->options);
1640         if (error)
1641                 goto out_fail;
1642
1643         setup(sb); /* flavour-specific stuff that needs options */
1644
1645         error = -EIO;
1646         sb_min_blocksize(sb, 512);
1647         bh = sb_bread(sb, 0);
1648         if (bh == NULL) {
1649                 fat_msg(sb, KERN_ERR, "unable to read boot sector");
1650                 goto out_fail;
1651         }
1652
1653         error = fat_read_bpb(sb, (struct fat_boot_sector *)bh->b_data, silent,
1654                 &bpb);
1655         if (error == -EINVAL && sbi->options.dos1xfloppy)
1656                 error = fat_read_static_bpb(sb,
1657                         (struct fat_boot_sector *)bh->b_data, silent, &bpb);
1658         brelse(bh);
1659
1660         if (error == -EINVAL)
1661                 goto out_invalid;
1662         else if (error)
1663                 goto out_fail;
1664
1665         logical_sector_size = bpb.fat_sector_size;
1666         sbi->sec_per_clus = bpb.fat_sec_per_clus;
1667
1668         error = -EIO;
1669         if (logical_sector_size < sb->s_blocksize) {
1670                 fat_msg(sb, KERN_ERR, "logical sector size too small for device"
1671                        " (logical sector size = %u)", logical_sector_size);
1672                 goto out_fail;
1673         }
1674
1675         if (logical_sector_size > sb->s_blocksize) {
1676                 struct buffer_head *bh_resize;
1677
1678                 if (!sb_set_blocksize(sb, logical_sector_size)) {
1679                         fat_msg(sb, KERN_ERR, "unable to set blocksize %u",
1680                                logical_sector_size);
1681                         goto out_fail;
1682                 }
1683
1684                 /* Verify that the larger boot sector is fully readable */
1685                 bh_resize = sb_bread(sb, 0);
1686                 if (bh_resize == NULL) {
1687                         fat_msg(sb, KERN_ERR, "unable to read boot sector"
1688                                " (logical sector size = %lu)",
1689                                sb->s_blocksize);
1690                         goto out_fail;
1691                 }
1692                 brelse(bh_resize);
1693         }
1694
1695         mutex_init(&sbi->s_lock);
1696         sbi->cluster_size = sb->s_blocksize * sbi->sec_per_clus;
1697         sbi->cluster_bits = ffs(sbi->cluster_size) - 1;
1698         sbi->fats = bpb.fat_fats;
1699         sbi->fat_bits = 0;              /* Don't know yet */
1700         sbi->fat_start = bpb.fat_reserved;
1701         sbi->fat_length = bpb.fat_fat_length;
1702         sbi->root_cluster = 0;
1703         sbi->free_clusters = -1;        /* Don't know yet */
1704         sbi->free_clus_valid = 0;
1705         sbi->prev_free = FAT_START_ENT;
1706         sb->s_maxbytes = 0xffffffff;
1707         fat_time_fat2unix(sbi, &ts, 0, cpu_to_le16(FAT_DATE_MIN), 0);
1708         sb->s_time_min = ts.tv_sec;
1709
1710         fat_time_fat2unix(sbi, &ts, cpu_to_le16(FAT_TIME_MAX),
1711                           cpu_to_le16(FAT_DATE_MAX), 0);
1712         sb->s_time_max = ts.tv_sec;
1713
1714         if (!sbi->fat_length && bpb.fat32_length) {
1715                 struct fat_boot_fsinfo *fsinfo;
1716                 struct buffer_head *fsinfo_bh;
1717
1718                 /* Must be FAT32 */
1719                 sbi->fat_bits = 32;
1720                 sbi->fat_length = bpb.fat32_length;
1721                 sbi->root_cluster = bpb.fat32_root_cluster;
1722
1723                 /* MC - if info_sector is 0, don't multiply by 0 */
1724                 sbi->fsinfo_sector = bpb.fat32_info_sector;
1725                 if (sbi->fsinfo_sector == 0)
1726                         sbi->fsinfo_sector = 1;
1727
1728                 fsinfo_bh = sb_bread(sb, sbi->fsinfo_sector);
1729                 if (fsinfo_bh == NULL) {
1730                         fat_msg(sb, KERN_ERR, "bread failed, FSINFO block"
1731                                " (sector = %lu)", sbi->fsinfo_sector);
1732                         goto out_fail;
1733                 }
1734
1735                 fsinfo = (struct fat_boot_fsinfo *)fsinfo_bh->b_data;
1736                 if (!IS_FSINFO(fsinfo)) {
1737                         fat_msg(sb, KERN_WARNING, "Invalid FSINFO signature: "
1738                                "0x%08x, 0x%08x (sector = %lu)",
1739                                le32_to_cpu(fsinfo->signature1),
1740                                le32_to_cpu(fsinfo->signature2),
1741                                sbi->fsinfo_sector);
1742                 } else {
1743                         if (sbi->options.usefree)
1744                                 sbi->free_clus_valid = 1;
1745                         sbi->free_clusters = le32_to_cpu(fsinfo->free_clusters);
1746                         sbi->prev_free = le32_to_cpu(fsinfo->next_cluster);
1747                 }
1748
1749                 brelse(fsinfo_bh);
1750         }
1751
1752         /* interpret volume ID as a little endian 32 bit integer */
1753         if (is_fat32(sbi))
1754                 sbi->vol_id = bpb.fat32_vol_id;
1755         else /* fat 16 or 12 */
1756                 sbi->vol_id = bpb.fat16_vol_id;
1757
1758         sbi->dir_per_block = sb->s_blocksize / sizeof(struct msdos_dir_entry);
1759         sbi->dir_per_block_bits = ffs(sbi->dir_per_block) - 1;
1760
1761         sbi->dir_start = sbi->fat_start + sbi->fats * sbi->fat_length;
1762         sbi->dir_entries = bpb.fat_dir_entries;
1763         if (sbi->dir_entries & (sbi->dir_per_block - 1)) {
1764                 if (!silent)
1765                         fat_msg(sb, KERN_ERR, "bogus number of directory entries"
1766                                " (%u)", sbi->dir_entries);
1767                 goto out_invalid;
1768         }
1769
1770         rootdir_sectors = sbi->dir_entries
1771                 * sizeof(struct msdos_dir_entry) / sb->s_blocksize;
1772         sbi->data_start = sbi->dir_start + rootdir_sectors;
1773         total_sectors = bpb.fat_sectors;
1774         if (total_sectors == 0)
1775                 total_sectors = bpb.fat_total_sect;
1776
1777         total_clusters = (total_sectors - sbi->data_start) / sbi->sec_per_clus;
1778
1779         if (!is_fat32(sbi))
1780                 sbi->fat_bits = (total_clusters > MAX_FAT12) ? 16 : 12;
1781
1782         /* some OSes set FAT_STATE_DIRTY and clean it on unmount. */
1783         if (is_fat32(sbi))
1784                 sbi->dirty = bpb.fat32_state & FAT_STATE_DIRTY;
1785         else /* fat 16 or 12 */
1786                 sbi->dirty = bpb.fat16_state & FAT_STATE_DIRTY;
1787
1788         /* check that FAT table does not overflow */
1789         fat_clusters = calc_fat_clusters(sb);
1790         total_clusters = min(total_clusters, fat_clusters - FAT_START_ENT);
1791         if (total_clusters > max_fat(sb)) {
1792                 if (!silent)
1793                         fat_msg(sb, KERN_ERR, "count of clusters too big (%u)",
1794                                total_clusters);
1795                 goto out_invalid;
1796         }
1797
1798         sbi->max_cluster = total_clusters + FAT_START_ENT;
1799         /* check the free_clusters, it's not necessarily correct */
1800         if (sbi->free_clusters != -1 && sbi->free_clusters > total_clusters)
1801                 sbi->free_clusters = -1;
1802         /* check the prev_free, it's not necessarily correct */
1803         sbi->prev_free %= sbi->max_cluster;
1804         if (sbi->prev_free < FAT_START_ENT)
1805                 sbi->prev_free = FAT_START_ENT;
1806
1807         /* set up enough so that it can read an inode */
1808         fat_hash_init(sb);
1809         dir_hash_init(sb);
1810         fat_ent_access_init(sb);
1811
1812         /*
1813          * The low byte of the first FAT entry must have the same value as
1814          * the media field of the boot sector. But in real world, too many
1815          * devices are writing wrong values. So, removed that validity check.
1816          *
1817          * The removed check compared the first FAT entry to a value dependent
1818          * on the media field like this:
1819          * == (0x0F00 | media), for FAT12
1820          * == (0XFF00 | media), for FAT16
1821          * == (0x0FFFFF | media), for FAT32
1822          */
1823
1824         error = -EINVAL;
1825         sprintf(buf, "cp%d", sbi->options.codepage);
1826         sbi->nls_disk = load_nls(buf);
1827         if (!sbi->nls_disk) {
1828                 fat_msg(sb, KERN_ERR, "codepage %s not found", buf);
1829                 goto out_fail;
1830         }
1831
1832         /* FIXME: utf8 is using iocharset for upper/lower conversion */
1833         if (sbi->options.isvfat) {
1834                 sbi->nls_io = load_nls(sbi->options.iocharset);
1835                 if (!sbi->nls_io) {
1836                         fat_msg(sb, KERN_ERR, "IO charset %s not found",
1837                                sbi->options.iocharset);
1838                         goto out_fail;
1839                 }
1840         }
1841
1842         error = -ENOMEM;
1843         fat_inode = new_inode(sb);
1844         if (!fat_inode)
1845                 goto out_fail;
1846         sbi->fat_inode = fat_inode;
1847
1848         fsinfo_inode = new_inode(sb);
1849         if (!fsinfo_inode)
1850                 goto out_fail;
1851         fsinfo_inode->i_ino = MSDOS_FSINFO_INO;
1852         sbi->fsinfo_inode = fsinfo_inode;
1853         insert_inode_hash(fsinfo_inode);
1854
1855         root_inode = new_inode(sb);
1856         if (!root_inode)
1857                 goto out_fail;
1858         root_inode->i_ino = MSDOS_ROOT_INO;
1859         inode_set_iversion(root_inode, 1);
1860         error = fat_read_root(root_inode);
1861         if (error < 0) {
1862                 iput(root_inode);
1863                 goto out_fail;
1864         }
1865         error = -ENOMEM;
1866         insert_inode_hash(root_inode);
1867         fat_attach(root_inode, 0);
1868         sb->s_root = d_make_root(root_inode);
1869         if (!sb->s_root) {
1870                 fat_msg(sb, KERN_ERR, "get root inode failed");
1871                 goto out_fail;
1872         }
1873
1874         if (sbi->options.discard) {
1875                 struct request_queue *q = bdev_get_queue(sb->s_bdev);
1876                 if (!blk_queue_discard(q))
1877                         fat_msg(sb, KERN_WARNING,
1878                                         "mounting with \"discard\" option, but "
1879                                         "the device does not support discard");
1880         }
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         if (fsinfo_inode)
1892                 iput(fsinfo_inode);
1893         if (fat_inode)
1894                 iput(fat_inode);
1895         unload_nls(sbi->nls_io);
1896         unload_nls(sbi->nls_disk);
1897         fat_reset_iocharset(&sbi->options);
1898         sb->s_fs_info = NULL;
1899         kfree(sbi);
1900         return error;
1901 }
1902
1903 EXPORT_SYMBOL_GPL(fat_fill_super);
1904
1905 /*
1906  * helper function for fat_flush_inodes.  This writes both the inode
1907  * and the file data blocks, waiting for in flight data blocks before
1908  * the start of the call.  It does not wait for any io started
1909  * during the call
1910  */
1911 static int writeback_inode(struct inode *inode)
1912 {
1913
1914         int ret;
1915
1916         /* if we used wait=1, sync_inode_metadata waits for the io for the
1917         * inode to finish.  So wait=0 is sent down to sync_inode_metadata
1918         * and filemap_fdatawrite is used for the data blocks
1919         */
1920         ret = sync_inode_metadata(inode, 0);
1921         if (!ret)
1922                 ret = filemap_fdatawrite(inode->i_mapping);
1923         return ret;
1924 }
1925
1926 /*
1927  * write data and metadata corresponding to i1 and i2.  The io is
1928  * started but we do not wait for any of it to finish.
1929  *
1930  * filemap_flush is used for the block device, so if there is a dirty
1931  * page for a block already in flight, we will not wait and start the
1932  * io over again
1933  */
1934 int fat_flush_inodes(struct super_block *sb, struct inode *i1, struct inode *i2)
1935 {
1936         int ret = 0;
1937         if (!MSDOS_SB(sb)->options.flush)
1938                 return 0;
1939         if (i1)
1940                 ret = writeback_inode(i1);
1941         if (!ret && i2)
1942                 ret = writeback_inode(i2);
1943         if (!ret)
1944                 ret = sync_blockdev_nowait(sb->s_bdev);
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");