linux/fs/fat/inode.c
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   1/*
   2 *  linux/fs/fat/inode.c
   3 *
   4 *  Written 1992,1993 by Werner Almesberger
   5 *  VFAT extensions by Gordon Chaffee, merged with msdos fs by Henrik Storner
   6 *  Rewritten for the constant inumbers support by Al Viro
   7 *
   8 *  Fixes:
   9 *
  10 *      Max Cohan: Fixed invalid FSINFO offset when info_sector is 0
  11 */
  12
  13#include <linux/module.h>
  14#include <linux/init.h>
  15#include <linux/time.h>
  16#include <linux/slab.h>
  17#include <linux/seq_file.h>
  18#include <linux/pagemap.h>
  19#include <linux/mpage.h>
  20#include <linux/buffer_head.h>
  21#include <linux/exportfs.h>
  22#include <linux/mount.h>
  23#include <linux/vfs.h>
  24#include <linux/parser.h>
  25#include <linux/uio.h>
  26#include <linux/writeback.h>
  27#include <linux/log2.h>
  28#include <linux/hash.h>
  29#include <asm/unaligned.h>
  30#include "fat.h"
  31
  32#ifndef CONFIG_FAT_DEFAULT_IOCHARSET
  33/* if user don't select VFAT, this is undefined. */
  34#define CONFIG_FAT_DEFAULT_IOCHARSET    ""
  35#endif
  36
  37static int fat_default_codepage = CONFIG_FAT_DEFAULT_CODEPAGE;
  38static char fat_default_iocharset[] = CONFIG_FAT_DEFAULT_IOCHARSET;
  39
  40
  41static int fat_add_cluster(struct inode *inode)
  42{
  43        int err, cluster;
  44
  45        err = fat_alloc_clusters(inode, &cluster, 1);
  46        if (err)
  47                return err;
  48        /* FIXME: this cluster should be added after data of this
  49         * cluster is writed */
  50        err = fat_chain_add(inode, cluster, 1);
  51        if (err)
  52                fat_free_clusters(inode, cluster);
  53        return err;
  54}
  55
  56static inline int __fat_get_block(struct inode *inode, sector_t iblock,
  57                                  unsigned long *max_blocks,
  58                                  struct buffer_head *bh_result, int create)
  59{
  60        struct super_block *sb = inode->i_sb;
  61        struct msdos_sb_info *sbi = MSDOS_SB(sb);
  62        unsigned long mapped_blocks;
  63        sector_t phys;
  64        int err, offset;
  65
  66        err = fat_bmap(inode, iblock, &phys, &mapped_blocks, create);
  67        if (err)
  68                return err;
  69        if (phys) {
  70                map_bh(bh_result, sb, phys);
  71                *max_blocks = min(mapped_blocks, *max_blocks);
  72                return 0;
  73        }
  74        if (!create)
  75                return 0;
  76
  77        if (iblock != MSDOS_I(inode)->mmu_private >> sb->s_blocksize_bits) {
  78                fat_fs_error(sb, "corrupted file size (i_pos %lld, %lld)",
  79                        MSDOS_I(inode)->i_pos, MSDOS_I(inode)->mmu_private);
  80                return -EIO;
  81        }
  82
  83        offset = (unsigned long)iblock & (sbi->sec_per_clus - 1);
  84        if (!offset) {
  85                /* TODO: multiple cluster allocation would be desirable. */
  86                err = fat_add_cluster(inode);
  87                if (err)
  88                        return err;
  89        }
  90        /* available blocks on this cluster */
  91        mapped_blocks = sbi->sec_per_clus - offset;
  92
  93        *max_blocks = min(mapped_blocks, *max_blocks);
  94        MSDOS_I(inode)->mmu_private += *max_blocks << sb->s_blocksize_bits;
  95
  96        err = fat_bmap(inode, iblock, &phys, &mapped_blocks, create);
  97        if (err)
  98                return err;
  99
 100        BUG_ON(!phys);
 101        BUG_ON(*max_blocks != mapped_blocks);
 102        set_buffer_new(bh_result);
 103        map_bh(bh_result, sb, phys);
 104
 105        return 0;
 106}
 107
 108static int fat_get_block(struct inode *inode, sector_t iblock,
 109                         struct buffer_head *bh_result, int create)
 110{
 111        struct super_block *sb = inode->i_sb;
 112        unsigned long max_blocks = bh_result->b_size >> inode->i_blkbits;
 113        int err;
 114
 115        err = __fat_get_block(inode, iblock, &max_blocks, bh_result, create);
 116        if (err)
 117                return err;
 118        bh_result->b_size = max_blocks << sb->s_blocksize_bits;
 119        return 0;
 120}
 121
 122static int fat_writepage(struct page *page, struct writeback_control *wbc)
 123{
 124        return block_write_full_page(page, fat_get_block, wbc);
 125}
 126
 127static int fat_writepages(struct address_space *mapping,
 128                          struct writeback_control *wbc)
 129{
 130        return mpage_writepages(mapping, wbc, fat_get_block);
 131}
 132
 133static int fat_readpage(struct file *file, struct page *page)
 134{
 135        return mpage_readpage(page, fat_get_block);
 136}
 137
 138static int fat_readpages(struct file *file, struct address_space *mapping,
 139                         struct list_head *pages, unsigned nr_pages)
 140{
 141        return mpage_readpages(mapping, pages, nr_pages, fat_get_block);
 142}
 143
 144static void fat_write_failed(struct address_space *mapping, loff_t to)
 145{
 146        struct inode *inode = mapping->host;
 147
 148        if (to > inode->i_size) {
 149                truncate_pagecache(inode, to, inode->i_size);
 150                fat_truncate_blocks(inode, inode->i_size);
 151        }
 152}
 153
 154static int fat_write_begin(struct file *file, struct address_space *mapping,
 155                        loff_t pos, unsigned len, unsigned flags,
 156                        struct page **pagep, void **fsdata)
 157{
 158        int err;
 159
 160        *pagep = NULL;
 161        err = cont_write_begin(file, mapping, pos, len, flags,
 162                                pagep, fsdata, fat_get_block,
 163                                &MSDOS_I(mapping->host)->mmu_private);
 164        if (err < 0)
 165                fat_write_failed(mapping, pos + len);
 166        return err;
 167}
 168
 169static int fat_write_end(struct file *file, struct address_space *mapping,
 170                        loff_t pos, unsigned len, unsigned copied,
 171                        struct page *pagep, void *fsdata)
 172{
 173        struct inode *inode = mapping->host;
 174        int err;
 175        err = generic_write_end(file, mapping, pos, len, copied, pagep, fsdata);
 176        if (err < len)
 177                fat_write_failed(mapping, pos + len);
 178        if (!(err < 0) && !(MSDOS_I(inode)->i_attrs & ATTR_ARCH)) {
 179                inode->i_mtime = inode->i_ctime = CURRENT_TIME_SEC;
 180                MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
 181                mark_inode_dirty(inode);
 182        }
 183        return err;
 184}
 185
 186static ssize_t fat_direct_IO(int rw, struct kiocb *iocb,
 187                             const struct iovec *iov,
 188                             loff_t offset, unsigned long nr_segs)
 189{
 190        struct file *file = iocb->ki_filp;
 191        struct address_space *mapping = file->f_mapping;
 192        struct inode *inode = mapping->host;
 193        ssize_t ret;
 194
 195        if (rw == WRITE) {
 196                /*
 197                 * FIXME: blockdev_direct_IO() doesn't use ->write_begin(),
 198                 * so we need to update the ->mmu_private to block boundary.
 199                 *
 200                 * But we must fill the remaining area or hole by nul for
 201                 * updating ->mmu_private.
 202                 *
 203                 * Return 0, and fallback to normal buffered write.
 204                 */
 205                loff_t size = offset + iov_length(iov, nr_segs);
 206                if (MSDOS_I(inode)->mmu_private < size)
 207                        return 0;
 208        }
 209
 210        /*
 211         * FAT need to use the DIO_LOCKING for avoiding the race
 212         * condition of fat_get_block() and ->truncate().
 213         */
 214        ret = blockdev_direct_IO(rw, iocb, inode, iov, offset, nr_segs,
 215                                 fat_get_block);
 216        if (ret < 0 && (rw & WRITE))
 217                fat_write_failed(mapping, offset + iov_length(iov, nr_segs));
 218
 219        return ret;
 220}
 221
 222static sector_t _fat_bmap(struct address_space *mapping, sector_t block)
 223{
 224        sector_t blocknr;
 225
 226        /* fat_get_cluster() assumes the requested blocknr isn't truncated. */
 227        down_read(&MSDOS_I(mapping->host)->truncate_lock);
 228        blocknr = generic_block_bmap(mapping, block, fat_get_block);
 229        up_read(&MSDOS_I(mapping->host)->truncate_lock);
 230
 231        return blocknr;
 232}
 233
 234static const struct address_space_operations fat_aops = {
 235        .readpage       = fat_readpage,
 236        .readpages      = fat_readpages,
 237        .writepage      = fat_writepage,
 238        .writepages     = fat_writepages,
 239        .write_begin    = fat_write_begin,
 240        .write_end      = fat_write_end,
 241        .direct_IO      = fat_direct_IO,
 242        .bmap           = _fat_bmap
 243};
 244
 245/*
 246 * New FAT inode stuff. We do the following:
 247 *      a) i_ino is constant and has nothing with on-disk location.
 248 *      b) FAT manages its own cache of directory entries.
 249 *      c) *This* cache is indexed by on-disk location.
 250 *      d) inode has an associated directory entry, all right, but
 251 *              it may be unhashed.
 252 *      e) currently entries are stored within struct inode. That should
 253 *              change.
 254 *      f) we deal with races in the following way:
 255 *              1. readdir() and lookup() do FAT-dir-cache lookup.
 256 *              2. rename() unhashes the F-d-c entry and rehashes it in
 257 *                      a new place.
 258 *              3. unlink() and rmdir() unhash F-d-c entry.
 259 *              4. fat_write_inode() checks whether the thing is unhashed.
 260 *                      If it is we silently return. If it isn't we do bread(),
 261 *                      check if the location is still valid and retry if it
 262 *                      isn't. Otherwise we do changes.
 263 *              5. Spinlock is used to protect hash/unhash/location check/lookup
 264 *              6. fat_evict_inode() unhashes the F-d-c entry.
 265 *              7. lookup() and readdir() do igrab() if they find a F-d-c entry
 266 *                      and consider negative result as cache miss.
 267 */
 268
 269static void fat_hash_init(struct super_block *sb)
 270{
 271        struct msdos_sb_info *sbi = MSDOS_SB(sb);
 272        int i;
 273
 274        spin_lock_init(&sbi->inode_hash_lock);
 275        for (i = 0; i < FAT_HASH_SIZE; i++)
 276                INIT_HLIST_HEAD(&sbi->inode_hashtable[i]);
 277}
 278
 279static inline unsigned long fat_hash(loff_t i_pos)
 280{
 281        return hash_32(i_pos, FAT_HASH_BITS);
 282}
 283
 284void fat_attach(struct inode *inode, loff_t i_pos)
 285{
 286        struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 287        struct hlist_head *head = sbi->inode_hashtable + fat_hash(i_pos);
 288
 289        spin_lock(&sbi->inode_hash_lock);
 290        MSDOS_I(inode)->i_pos = i_pos;
 291        hlist_add_head(&MSDOS_I(inode)->i_fat_hash, head);
 292        spin_unlock(&sbi->inode_hash_lock);
 293}
 294EXPORT_SYMBOL_GPL(fat_attach);
 295
 296void fat_detach(struct inode *inode)
 297{
 298        struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 299        spin_lock(&sbi->inode_hash_lock);
 300        MSDOS_I(inode)->i_pos = 0;
 301        hlist_del_init(&MSDOS_I(inode)->i_fat_hash);
 302        spin_unlock(&sbi->inode_hash_lock);
 303}
 304EXPORT_SYMBOL_GPL(fat_detach);
 305
 306struct inode *fat_iget(struct super_block *sb, loff_t i_pos)
 307{
 308        struct msdos_sb_info *sbi = MSDOS_SB(sb);
 309        struct hlist_head *head = sbi->inode_hashtable + fat_hash(i_pos);
 310        struct hlist_node *_p;
 311        struct msdos_inode_info *i;
 312        struct inode *inode = NULL;
 313
 314        spin_lock(&sbi->inode_hash_lock);
 315        hlist_for_each_entry(i, _p, head, i_fat_hash) {
 316                BUG_ON(i->vfs_inode.i_sb != sb);
 317                if (i->i_pos != i_pos)
 318                        continue;
 319                inode = igrab(&i->vfs_inode);
 320                if (inode)
 321                        break;
 322        }
 323        spin_unlock(&sbi->inode_hash_lock);
 324        return inode;
 325}
 326
 327static int is_exec(unsigned char *extension)
 328{
 329        unsigned char *exe_extensions = "EXECOMBAT", *walk;
 330
 331        for (walk = exe_extensions; *walk; walk += 3)
 332                if (!strncmp(extension, walk, 3))
 333                        return 1;
 334        return 0;
 335}
 336
 337static int fat_calc_dir_size(struct inode *inode)
 338{
 339        struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 340        int ret, fclus, dclus;
 341
 342        inode->i_size = 0;
 343        if (MSDOS_I(inode)->i_start == 0)
 344                return 0;
 345
 346        ret = fat_get_cluster(inode, FAT_ENT_EOF, &fclus, &dclus);
 347        if (ret < 0)
 348                return ret;
 349        inode->i_size = (fclus + 1) << sbi->cluster_bits;
 350
 351        return 0;
 352}
 353
 354/* doesn't deal with root inode */
 355static int fat_fill_inode(struct inode *inode, struct msdos_dir_entry *de)
 356{
 357        struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 358        int error;
 359
 360        MSDOS_I(inode)->i_pos = 0;
 361        inode->i_uid = sbi->options.fs_uid;
 362        inode->i_gid = sbi->options.fs_gid;
 363        inode->i_version++;
 364        inode->i_generation = get_seconds();
 365
 366        if ((de->attr & ATTR_DIR) && !IS_FREE(de->name)) {
 367                inode->i_generation &= ~1;
 368                inode->i_mode = fat_make_mode(sbi, de->attr, S_IRWXUGO);
 369                inode->i_op = sbi->dir_ops;
 370                inode->i_fop = &fat_dir_operations;
 371
 372                MSDOS_I(inode)->i_start = fat_get_start(sbi, de);
 373                MSDOS_I(inode)->i_logstart = MSDOS_I(inode)->i_start;
 374                error = fat_calc_dir_size(inode);
 375                if (error < 0)
 376                        return error;
 377                MSDOS_I(inode)->mmu_private = inode->i_size;
 378
 379                set_nlink(inode, fat_subdirs(inode));
 380        } else { /* not a directory */
 381                inode->i_generation |= 1;
 382                inode->i_mode = fat_make_mode(sbi, de->attr,
 383                        ((sbi->options.showexec && !is_exec(de->name + 8))
 384                         ? S_IRUGO|S_IWUGO : S_IRWXUGO));
 385                MSDOS_I(inode)->i_start = fat_get_start(sbi, de);
 386
 387                MSDOS_I(inode)->i_logstart = MSDOS_I(inode)->i_start;
 388                inode->i_size = le32_to_cpu(de->size);
 389                inode->i_op = &fat_file_inode_operations;
 390                inode->i_fop = &fat_file_operations;
 391                inode->i_mapping->a_ops = &fat_aops;
 392                MSDOS_I(inode)->mmu_private = inode->i_size;
 393        }
 394        if (de->attr & ATTR_SYS) {
 395                if (sbi->options.sys_immutable)
 396                        inode->i_flags |= S_IMMUTABLE;
 397        }
 398        fat_save_attrs(inode, de->attr);
 399
 400        inode->i_blocks = ((inode->i_size + (sbi->cluster_size - 1))
 401                           & ~((loff_t)sbi->cluster_size - 1)) >> 9;
 402
 403        fat_time_fat2unix(sbi, &inode->i_mtime, de->time, de->date, 0);
 404        if (sbi->options.isvfat) {
 405                fat_time_fat2unix(sbi, &inode->i_ctime, de->ctime,
 406                                  de->cdate, de->ctime_cs);
 407                fat_time_fat2unix(sbi, &inode->i_atime, 0, de->adate, 0);
 408        } else
 409                inode->i_ctime = inode->i_atime = inode->i_mtime;
 410
 411        return 0;
 412}
 413
 414struct inode *fat_build_inode(struct super_block *sb,
 415                        struct msdos_dir_entry *de, loff_t i_pos)
 416{
 417        struct inode *inode;
 418        int err;
 419
 420        inode = fat_iget(sb, i_pos);
 421        if (inode)
 422                goto out;
 423        inode = new_inode(sb);
 424        if (!inode) {
 425                inode = ERR_PTR(-ENOMEM);
 426                goto out;
 427        }
 428        inode->i_ino = iunique(sb, MSDOS_ROOT_INO);
 429        inode->i_version = 1;
 430        err = fat_fill_inode(inode, de);
 431        if (err) {
 432                iput(inode);
 433                inode = ERR_PTR(err);
 434                goto out;
 435        }
 436        fat_attach(inode, i_pos);
 437        insert_inode_hash(inode);
 438out:
 439        return inode;
 440}
 441
 442EXPORT_SYMBOL_GPL(fat_build_inode);
 443
 444static void fat_evict_inode(struct inode *inode)
 445{
 446        truncate_inode_pages(&inode->i_data, 0);
 447        if (!inode->i_nlink) {
 448                inode->i_size = 0;
 449                fat_truncate_blocks(inode, 0);
 450        }
 451        invalidate_inode_buffers(inode);
 452        clear_inode(inode);
 453        fat_cache_inval_inode(inode);
 454        fat_detach(inode);
 455}
 456
 457static void fat_put_super(struct super_block *sb)
 458{
 459        struct msdos_sb_info *sbi = MSDOS_SB(sb);
 460
 461        iput(sbi->fsinfo_inode);
 462        iput(sbi->fat_inode);
 463
 464        unload_nls(sbi->nls_disk);
 465        unload_nls(sbi->nls_io);
 466
 467        if (sbi->options.iocharset != fat_default_iocharset)
 468                kfree(sbi->options.iocharset);
 469
 470        sb->s_fs_info = NULL;
 471        kfree(sbi);
 472}
 473
 474static struct kmem_cache *fat_inode_cachep;
 475
 476static struct inode *fat_alloc_inode(struct super_block *sb)
 477{
 478        struct msdos_inode_info *ei;
 479        ei = kmem_cache_alloc(fat_inode_cachep, GFP_NOFS);
 480        if (!ei)
 481                return NULL;
 482
 483        init_rwsem(&ei->truncate_lock);
 484        return &ei->vfs_inode;
 485}
 486
 487static void fat_i_callback(struct rcu_head *head)
 488{
 489        struct inode *inode = container_of(head, struct inode, i_rcu);
 490        kmem_cache_free(fat_inode_cachep, MSDOS_I(inode));
 491}
 492
 493static void fat_destroy_inode(struct inode *inode)
 494{
 495        call_rcu(&inode->i_rcu, fat_i_callback);
 496}
 497
 498static void init_once(void *foo)
 499{
 500        struct msdos_inode_info *ei = (struct msdos_inode_info *)foo;
 501
 502        spin_lock_init(&ei->cache_lru_lock);
 503        ei->nr_caches = 0;
 504        ei->cache_valid_id = FAT_CACHE_VALID + 1;
 505        INIT_LIST_HEAD(&ei->cache_lru);
 506        INIT_HLIST_NODE(&ei->i_fat_hash);
 507        inode_init_once(&ei->vfs_inode);
 508}
 509
 510static int __init fat_init_inodecache(void)
 511{
 512        fat_inode_cachep = kmem_cache_create("fat_inode_cache",
 513                                             sizeof(struct msdos_inode_info),
 514                                             0, (SLAB_RECLAIM_ACCOUNT|
 515                                                SLAB_MEM_SPREAD),
 516                                             init_once);
 517        if (fat_inode_cachep == NULL)
 518                return -ENOMEM;
 519        return 0;
 520}
 521
 522static void __exit fat_destroy_inodecache(void)
 523{
 524        kmem_cache_destroy(fat_inode_cachep);
 525}
 526
 527static int fat_remount(struct super_block *sb, int *flags, char *data)
 528{
 529        struct msdos_sb_info *sbi = MSDOS_SB(sb);
 530        *flags |= MS_NODIRATIME | (sbi->options.isvfat ? 0 : MS_NOATIME);
 531        return 0;
 532}
 533
 534static int fat_statfs(struct dentry *dentry, struct kstatfs *buf)
 535{
 536        struct super_block *sb = dentry->d_sb;
 537        struct msdos_sb_info *sbi = MSDOS_SB(sb);
 538        u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
 539
 540        /* If the count of free cluster is still unknown, counts it here. */
 541        if (sbi->free_clusters == -1 || !sbi->free_clus_valid) {
 542                int err = fat_count_free_clusters(dentry->d_sb);
 543                if (err)
 544                        return err;
 545        }
 546
 547        buf->f_type = dentry->d_sb->s_magic;
 548        buf->f_bsize = sbi->cluster_size;
 549        buf->f_blocks = sbi->max_cluster - FAT_START_ENT;
 550        buf->f_bfree = sbi->free_clusters;
 551        buf->f_bavail = sbi->free_clusters;
 552        buf->f_fsid.val[0] = (u32)id;
 553        buf->f_fsid.val[1] = (u32)(id >> 32);
 554        buf->f_namelen =
 555                (sbi->options.isvfat ? FAT_LFN_LEN : 12) * NLS_MAX_CHARSET_SIZE;
 556
 557        return 0;
 558}
 559
 560static inline loff_t fat_i_pos_read(struct msdos_sb_info *sbi,
 561                                    struct inode *inode)
 562{
 563        loff_t i_pos;
 564#if BITS_PER_LONG == 32
 565        spin_lock(&sbi->inode_hash_lock);
 566#endif
 567        i_pos = MSDOS_I(inode)->i_pos;
 568#if BITS_PER_LONG == 32
 569        spin_unlock(&sbi->inode_hash_lock);
 570#endif
 571        return i_pos;
 572}
 573
 574static int __fat_write_inode(struct inode *inode, int wait)
 575{
 576        struct super_block *sb = inode->i_sb;
 577        struct msdos_sb_info *sbi = MSDOS_SB(sb);
 578        struct buffer_head *bh;
 579        struct msdos_dir_entry *raw_entry;
 580        loff_t i_pos;
 581        int err;
 582
 583        if (inode->i_ino == MSDOS_ROOT_INO)
 584                return 0;
 585
 586retry:
 587        i_pos = fat_i_pos_read(sbi, inode);
 588        if (!i_pos)
 589                return 0;
 590
 591        bh = sb_bread(sb, i_pos >> sbi->dir_per_block_bits);
 592        if (!bh) {
 593                fat_msg(sb, KERN_ERR, "unable to read inode block "
 594                       "for updating (i_pos %lld)", i_pos);
 595                return -EIO;
 596        }
 597        spin_lock(&sbi->inode_hash_lock);
 598        if (i_pos != MSDOS_I(inode)->i_pos) {
 599                spin_unlock(&sbi->inode_hash_lock);
 600                brelse(bh);
 601                goto retry;
 602        }
 603
 604        raw_entry = &((struct msdos_dir_entry *) (bh->b_data))
 605            [i_pos & (sbi->dir_per_block - 1)];
 606        if (S_ISDIR(inode->i_mode))
 607                raw_entry->size = 0;
 608        else
 609                raw_entry->size = cpu_to_le32(inode->i_size);
 610        raw_entry->attr = fat_make_attrs(inode);
 611        fat_set_start(raw_entry, MSDOS_I(inode)->i_logstart);
 612        fat_time_unix2fat(sbi, &inode->i_mtime, &raw_entry->time,
 613                          &raw_entry->date, NULL);
 614        if (sbi->options.isvfat) {
 615                __le16 atime;
 616                fat_time_unix2fat(sbi, &inode->i_ctime, &raw_entry->ctime,
 617                                  &raw_entry->cdate, &raw_entry->ctime_cs);
 618                fat_time_unix2fat(sbi, &inode->i_atime, &atime,
 619                                  &raw_entry->adate, NULL);
 620        }
 621        spin_unlock(&sbi->inode_hash_lock);
 622        mark_buffer_dirty(bh);
 623        err = 0;
 624        if (wait)
 625                err = sync_dirty_buffer(bh);
 626        brelse(bh);
 627        return err;
 628}
 629
 630static int fat_write_inode(struct inode *inode, struct writeback_control *wbc)
 631{
 632        int err;
 633
 634        if (inode->i_ino == MSDOS_FSINFO_INO) {
 635                struct super_block *sb = inode->i_sb;
 636
 637                lock_super(sb);
 638                err = fat_clusters_flush(sb);
 639                unlock_super(sb);
 640        } else
 641                err = __fat_write_inode(inode, wbc->sync_mode == WB_SYNC_ALL);
 642
 643        return err;
 644}
 645
 646int fat_sync_inode(struct inode *inode)
 647{
 648        return __fat_write_inode(inode, 1);
 649}
 650
 651EXPORT_SYMBOL_GPL(fat_sync_inode);
 652
 653static int fat_show_options(struct seq_file *m, struct dentry *root);
 654static const struct super_operations fat_sops = {
 655        .alloc_inode    = fat_alloc_inode,
 656        .destroy_inode  = fat_destroy_inode,
 657        .write_inode    = fat_write_inode,
 658        .evict_inode    = fat_evict_inode,
 659        .put_super      = fat_put_super,
 660        .statfs         = fat_statfs,
 661        .remount_fs     = fat_remount,
 662
 663        .show_options   = fat_show_options,
 664};
 665
 666/*
 667 * a FAT file handle with fhtype 3 is
 668 *  0/  i_ino - for fast, reliable lookup if still in the cache
 669 *  1/  i_generation - to see if i_ino is still valid
 670 *          bit 0 == 0 iff directory
 671 *  2/  i_pos(8-39) - if ino has changed, but still in cache
 672 *  3/  i_pos(4-7)|i_logstart - to semi-verify inode found at i_pos
 673 *  4/  i_pos(0-3)|parent->i_logstart - maybe used to hunt for the file on disc
 674 *
 675 * Hack for NFSv2: Maximum FAT entry number is 28bits and maximum
 676 * i_pos is 40bits (blocknr(32) + dir offset(8)), so two 4bits
 677 * of i_logstart is used to store the directory entry offset.
 678 */
 679
 680static struct dentry *fat_fh_to_dentry(struct super_block *sb,
 681                struct fid *fid, int fh_len, int fh_type)
 682{
 683        struct inode *inode = NULL;
 684        u32 *fh = fid->raw;
 685
 686        if (fh_len < 5 || fh_type != 3)
 687                return NULL;
 688
 689        inode = ilookup(sb, fh[0]);
 690        if (!inode || inode->i_generation != fh[1]) {
 691                if (inode)
 692                        iput(inode);
 693                inode = NULL;
 694        }
 695        if (!inode) {
 696                loff_t i_pos;
 697                int i_logstart = fh[3] & 0x0fffffff;
 698
 699                i_pos = (loff_t)fh[2] << 8;
 700                i_pos |= ((fh[3] >> 24) & 0xf0) | (fh[4] >> 28);
 701
 702                /* try 2 - see if i_pos is in F-d-c
 703                 * require i_logstart to be the same
 704                 * Will fail if you truncate and then re-write
 705                 */
 706
 707                inode = fat_iget(sb, i_pos);
 708                if (inode && MSDOS_I(inode)->i_logstart != i_logstart) {
 709                        iput(inode);
 710                        inode = NULL;
 711                }
 712        }
 713
 714        /*
 715         * For now, do nothing if the inode is not found.
 716         *
 717         * What we could do is:
 718         *
 719         *      - follow the file starting at fh[4], and record the ".." entry,
 720         *        and the name of the fh[2] entry.
 721         *      - then follow the ".." file finding the next step up.
 722         *
 723         * This way we build a path to the root of the tree. If this works, we
 724         * lookup the path and so get this inode into the cache.  Finally try
 725         * the fat_iget lookup again.  If that fails, then we are totally out
 726         * of luck.  But all that is for another day
 727         */
 728        return d_obtain_alias(inode);
 729}
 730
 731static int
 732fat_encode_fh(struct inode *inode, __u32 *fh, int *lenp, struct inode *parent)
 733{
 734        int len = *lenp;
 735        struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 736        loff_t i_pos;
 737
 738        if (len < 5) {
 739                *lenp = 5;
 740                return 255; /* no room */
 741        }
 742
 743        i_pos = fat_i_pos_read(sbi, inode);
 744        *lenp = 5;
 745        fh[0] = inode->i_ino;
 746        fh[1] = inode->i_generation;
 747        fh[2] = i_pos >> 8;
 748        fh[3] = ((i_pos & 0xf0) << 24) | MSDOS_I(inode)->i_logstart;
 749        fh[4] = (i_pos & 0x0f) << 28;
 750        if (parent)
 751                fh[4] |= MSDOS_I(parent)->i_logstart;
 752        return 3;
 753}
 754
 755static struct dentry *fat_get_parent(struct dentry *child)
 756{
 757        struct super_block *sb = child->d_sb;
 758        struct buffer_head *bh;
 759        struct msdos_dir_entry *de;
 760        loff_t i_pos;
 761        struct dentry *parent;
 762        struct inode *inode;
 763        int err;
 764
 765        lock_super(sb);
 766
 767        err = fat_get_dotdot_entry(child->d_inode, &bh, &de, &i_pos);
 768        if (err) {
 769                parent = ERR_PTR(err);
 770                goto out;
 771        }
 772        inode = fat_build_inode(sb, de, i_pos);
 773        brelse(bh);
 774
 775        parent = d_obtain_alias(inode);
 776out:
 777        unlock_super(sb);
 778
 779        return parent;
 780}
 781
 782static const struct export_operations fat_export_ops = {
 783        .encode_fh      = fat_encode_fh,
 784        .fh_to_dentry   = fat_fh_to_dentry,
 785        .get_parent     = fat_get_parent,
 786};
 787
 788static int fat_show_options(struct seq_file *m, struct dentry *root)
 789{
 790        struct msdos_sb_info *sbi = MSDOS_SB(root->d_sb);
 791        struct fat_mount_options *opts = &sbi->options;
 792        int isvfat = opts->isvfat;
 793
 794        if (opts->fs_uid != 0)
 795                seq_printf(m, ",uid=%u", opts->fs_uid);
 796        if (opts->fs_gid != 0)
 797                seq_printf(m, ",gid=%u", opts->fs_gid);
 798        seq_printf(m, ",fmask=%04o", opts->fs_fmask);
 799        seq_printf(m, ",dmask=%04o", opts->fs_dmask);
 800        if (opts->allow_utime)
 801                seq_printf(m, ",allow_utime=%04o", opts->allow_utime);
 802        if (sbi->nls_disk)
 803                seq_printf(m, ",codepage=%s", sbi->nls_disk->charset);
 804        if (isvfat) {
 805                if (sbi->nls_io)
 806                        seq_printf(m, ",iocharset=%s", sbi->nls_io->charset);
 807
 808                switch (opts->shortname) {
 809                case VFAT_SFN_DISPLAY_WIN95 | VFAT_SFN_CREATE_WIN95:
 810                        seq_puts(m, ",shortname=win95");
 811                        break;
 812                case VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WINNT:
 813                        seq_puts(m, ",shortname=winnt");
 814                        break;
 815                case VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WIN95:
 816                        seq_puts(m, ",shortname=mixed");
 817                        break;
 818                case VFAT_SFN_DISPLAY_LOWER | VFAT_SFN_CREATE_WIN95:
 819                        seq_puts(m, ",shortname=lower");
 820                        break;
 821                default:
 822                        seq_puts(m, ",shortname=unknown");
 823                        break;
 824                }
 825        }
 826        if (opts->name_check != 'n')
 827                seq_printf(m, ",check=%c", opts->name_check);
 828        if (opts->usefree)
 829                seq_puts(m, ",usefree");
 830        if (opts->quiet)
 831                seq_puts(m, ",quiet");
 832        if (opts->showexec)
 833                seq_puts(m, ",showexec");
 834        if (opts->sys_immutable)
 835                seq_puts(m, ",sys_immutable");
 836        if (!isvfat) {
 837                if (opts->dotsOK)
 838                        seq_puts(m, ",dotsOK=yes");
 839                if (opts->nocase)
 840                        seq_puts(m, ",nocase");
 841        } else {
 842                if (opts->utf8)
 843                        seq_puts(m, ",utf8");
 844                if (opts->unicode_xlate)
 845                        seq_puts(m, ",uni_xlate");
 846                if (!opts->numtail)
 847                        seq_puts(m, ",nonumtail");
 848                if (opts->rodir)
 849                        seq_puts(m, ",rodir");
 850        }
 851        if (opts->flush)
 852                seq_puts(m, ",flush");
 853        if (opts->tz_utc)
 854                seq_puts(m, ",tz=UTC");
 855        if (opts->errors == FAT_ERRORS_CONT)
 856                seq_puts(m, ",errors=continue");
 857        else if (opts->errors == FAT_ERRORS_PANIC)
 858                seq_puts(m, ",errors=panic");
 859        else
 860                seq_puts(m, ",errors=remount-ro");
 861        if (opts->discard)
 862                seq_puts(m, ",discard");
 863
 864        return 0;
 865}
 866
 867enum {
 868        Opt_check_n, Opt_check_r, Opt_check_s, Opt_uid, Opt_gid,
 869        Opt_umask, Opt_dmask, Opt_fmask, Opt_allow_utime, Opt_codepage,
 870        Opt_usefree, Opt_nocase, Opt_quiet, Opt_showexec, Opt_debug,
 871        Opt_immutable, Opt_dots, Opt_nodots,
 872        Opt_charset, Opt_shortname_lower, Opt_shortname_win95,
 873        Opt_shortname_winnt, Opt_shortname_mixed, Opt_utf8_no, Opt_utf8_yes,
 874        Opt_uni_xl_no, Opt_uni_xl_yes, Opt_nonumtail_no, Opt_nonumtail_yes,
 875        Opt_obsolete, Opt_flush, Opt_tz_utc, Opt_rodir, Opt_err_cont,
 876        Opt_err_panic, Opt_err_ro, Opt_discard, Opt_err,
 877};
 878
 879static const match_table_t fat_tokens = {
 880        {Opt_check_r, "check=relaxed"},
 881        {Opt_check_s, "check=strict"},
 882        {Opt_check_n, "check=normal"},
 883        {Opt_check_r, "check=r"},
 884        {Opt_check_s, "check=s"},
 885        {Opt_check_n, "check=n"},
 886        {Opt_uid, "uid=%u"},
 887        {Opt_gid, "gid=%u"},
 888        {Opt_umask, "umask=%o"},
 889        {Opt_dmask, "dmask=%o"},
 890        {Opt_fmask, "fmask=%o"},
 891        {Opt_allow_utime, "allow_utime=%o"},
 892        {Opt_codepage, "codepage=%u"},
 893        {Opt_usefree, "usefree"},
 894        {Opt_nocase, "nocase"},
 895        {Opt_quiet, "quiet"},
 896        {Opt_showexec, "showexec"},
 897        {Opt_debug, "debug"},
 898        {Opt_immutable, "sys_immutable"},
 899        {Opt_flush, "flush"},
 900        {Opt_tz_utc, "tz=UTC"},
 901        {Opt_err_cont, "errors=continue"},
 902        {Opt_err_panic, "errors=panic"},
 903        {Opt_err_ro, "errors=remount-ro"},
 904        {Opt_discard, "discard"},
 905        {Opt_obsolete, "conv=binary"},
 906        {Opt_obsolete, "conv=text"},
 907        {Opt_obsolete, "conv=auto"},
 908        {Opt_obsolete, "conv=b"},
 909        {Opt_obsolete, "conv=t"},
 910        {Opt_obsolete, "conv=a"},
 911        {Opt_obsolete, "fat=%u"},
 912        {Opt_obsolete, "blocksize=%u"},
 913        {Opt_obsolete, "cvf_format=%20s"},
 914        {Opt_obsolete, "cvf_options=%100s"},
 915        {Opt_obsolete, "posix"},
 916        {Opt_err, NULL},
 917};
 918static const match_table_t msdos_tokens = {
 919        {Opt_nodots, "nodots"},
 920        {Opt_nodots, "dotsOK=no"},
 921        {Opt_dots, "dots"},
 922        {Opt_dots, "dotsOK=yes"},
 923        {Opt_err, NULL}
 924};
 925static const match_table_t vfat_tokens = {
 926        {Opt_charset, "iocharset=%s"},
 927        {Opt_shortname_lower, "shortname=lower"},
 928        {Opt_shortname_win95, "shortname=win95"},
 929        {Opt_shortname_winnt, "shortname=winnt"},
 930        {Opt_shortname_mixed, "shortname=mixed"},
 931        {Opt_utf8_no, "utf8=0"},                /* 0 or no or false */
 932        {Opt_utf8_no, "utf8=no"},
 933        {Opt_utf8_no, "utf8=false"},
 934        {Opt_utf8_yes, "utf8=1"},               /* empty or 1 or yes or true */
 935        {Opt_utf8_yes, "utf8=yes"},
 936        {Opt_utf8_yes, "utf8=true"},
 937        {Opt_utf8_yes, "utf8"},
 938        {Opt_uni_xl_no, "uni_xlate=0"},         /* 0 or no or false */
 939        {Opt_uni_xl_no, "uni_xlate=no"},
 940        {Opt_uni_xl_no, "uni_xlate=false"},
 941        {Opt_uni_xl_yes, "uni_xlate=1"},        /* empty or 1 or yes or true */
 942        {Opt_uni_xl_yes, "uni_xlate=yes"},
 943        {Opt_uni_xl_yes, "uni_xlate=true"},
 944        {Opt_uni_xl_yes, "uni_xlate"},
 945        {Opt_nonumtail_no, "nonumtail=0"},      /* 0 or no or false */
 946        {Opt_nonumtail_no, "nonumtail=no"},
 947        {Opt_nonumtail_no, "nonumtail=false"},
 948        {Opt_nonumtail_yes, "nonumtail=1"},     /* empty or 1 or yes or true */
 949        {Opt_nonumtail_yes, "nonumtail=yes"},
 950        {Opt_nonumtail_yes, "nonumtail=true"},
 951        {Opt_nonumtail_yes, "nonumtail"},
 952        {Opt_rodir, "rodir"},
 953        {Opt_err, NULL}
 954};
 955
 956static int parse_options(struct super_block *sb, char *options, int is_vfat,
 957                         int silent, int *debug, struct fat_mount_options *opts)
 958{
 959        char *p;
 960        substring_t args[MAX_OPT_ARGS];
 961        int option;
 962        char *iocharset;
 963
 964        opts->isvfat = is_vfat;
 965
 966        opts->fs_uid = current_uid();
 967        opts->fs_gid = current_gid();
 968        opts->fs_fmask = opts->fs_dmask = current_umask();
 969        opts->allow_utime = -1;
 970        opts->codepage = fat_default_codepage;
 971        opts->iocharset = fat_default_iocharset;
 972        if (is_vfat) {
 973                opts->shortname = VFAT_SFN_DISPLAY_WINNT|VFAT_SFN_CREATE_WIN95;
 974                opts->rodir = 0;
 975        } else {
 976                opts->shortname = 0;
 977                opts->rodir = 1;
 978        }
 979        opts->name_check = 'n';
 980        opts->quiet = opts->showexec = opts->sys_immutable = opts->dotsOK =  0;
 981        opts->utf8 = opts->unicode_xlate = 0;
 982        opts->numtail = 1;
 983        opts->usefree = opts->nocase = 0;
 984        opts->tz_utc = 0;
 985        opts->errors = FAT_ERRORS_RO;
 986        *debug = 0;
 987
 988        if (!options)
 989                goto out;
 990
 991        while ((p = strsep(&options, ",")) != NULL) {
 992                int token;
 993                if (!*p)
 994                        continue;
 995
 996                token = match_token(p, fat_tokens, args);
 997                if (token == Opt_err) {
 998                        if (is_vfat)
 999                                token = match_token(p, vfat_tokens, args);
1000                        else
1001                                token = match_token(p, msdos_tokens, args);
1002                }
1003                switch (token) {
1004                case Opt_check_s:
1005                        opts->name_check = 's';
1006                        break;
1007                case Opt_check_r:
1008                        opts->name_check = 'r';
1009                        break;
1010                case Opt_check_n:
1011                        opts->name_check = 'n';
1012                        break;
1013                case Opt_usefree:
1014                        opts->usefree = 1;
1015                        break;
1016                case Opt_nocase:
1017                        if (!is_vfat)
1018                                opts->nocase = 1;
1019                        else {
1020                                /* for backward compatibility */
1021                                opts->shortname = VFAT_SFN_DISPLAY_WIN95
1022                                        | VFAT_SFN_CREATE_WIN95;
1023                        }
1024                        break;
1025                case Opt_quiet:
1026                        opts->quiet = 1;
1027                        break;
1028                case Opt_showexec:
1029                        opts->showexec = 1;
1030                        break;
1031                case Opt_debug:
1032                        *debug = 1;
1033                        break;
1034                case Opt_immutable:
1035                        opts->sys_immutable = 1;
1036                        break;
1037                case Opt_uid:
1038                        if (match_int(&args[0], &option))
1039                                return 0;
1040                        opts->fs_uid = option;
1041                        break;
1042                case Opt_gid:
1043                        if (match_int(&args[0], &option))
1044                                return 0;
1045                        opts->fs_gid = option;
1046                        break;
1047                case Opt_umask:
1048                        if (match_octal(&args[0], &option))
1049                                return 0;
1050                        opts->fs_fmask = opts->fs_dmask = option;
1051                        break;
1052                case Opt_dmask:
1053                        if (match_octal(&args[0], &option))
1054                                return 0;
1055                        opts->fs_dmask = option;
1056                        break;
1057                case Opt_fmask:
1058                        if (match_octal(&args[0], &option))
1059                                return 0;
1060                        opts->fs_fmask = option;
1061                        break;
1062                case Opt_allow_utime:
1063                        if (match_octal(&args[0], &option))
1064                                return 0;
1065                        opts->allow_utime = option & (S_IWGRP | S_IWOTH);
1066                        break;
1067                case Opt_codepage:
1068                        if (match_int(&args[0], &option))
1069                                return 0;
1070                        opts->codepage = option;
1071                        break;
1072                case Opt_flush:
1073                        opts->flush = 1;
1074                        break;
1075                case Opt_tz_utc:
1076                        opts->tz_utc = 1;
1077                        break;
1078                case Opt_err_cont:
1079                        opts->errors = FAT_ERRORS_CONT;
1080                        break;
1081                case Opt_err_panic:
1082                        opts->errors = FAT_ERRORS_PANIC;
1083                        break;
1084                case Opt_err_ro:
1085                        opts->errors = FAT_ERRORS_RO;
1086                        break;
1087
1088                /* msdos specific */
1089                case Opt_dots:
1090                        opts->dotsOK = 1;
1091                        break;
1092                case Opt_nodots:
1093                        opts->dotsOK = 0;
1094                        break;
1095
1096                /* vfat specific */
1097                case Opt_charset:
1098                        if (opts->iocharset != fat_default_iocharset)
1099                                kfree(opts->iocharset);
1100                        iocharset = match_strdup(&args[0]);
1101                        if (!iocharset)
1102                                return -ENOMEM;
1103                        opts->iocharset = iocharset;
1104                        break;
1105                case Opt_shortname_lower:
1106                        opts->shortname = VFAT_SFN_DISPLAY_LOWER
1107                                        | VFAT_SFN_CREATE_WIN95;
1108                        break;
1109                case Opt_shortname_win95:
1110                        opts->shortname = VFAT_SFN_DISPLAY_WIN95
1111                                        | VFAT_SFN_CREATE_WIN95;
1112                        break;
1113                case Opt_shortname_winnt:
1114                        opts->shortname = VFAT_SFN_DISPLAY_WINNT
1115                                        | VFAT_SFN_CREATE_WINNT;
1116                        break;
1117                case Opt_shortname_mixed:
1118                        opts->shortname = VFAT_SFN_DISPLAY_WINNT
1119                                        | VFAT_SFN_CREATE_WIN95;
1120                        break;
1121                case Opt_utf8_no:               /* 0 or no or false */
1122                        opts->utf8 = 0;
1123                        break;
1124                case Opt_utf8_yes:              /* empty or 1 or yes or true */
1125                        opts->utf8 = 1;
1126                        break;
1127                case Opt_uni_xl_no:             /* 0 or no or false */
1128                        opts->unicode_xlate = 0;
1129                        break;
1130                case Opt_uni_xl_yes:            /* empty or 1 or yes or true */
1131                        opts->unicode_xlate = 1;
1132                        break;
1133                case Opt_nonumtail_no:          /* 0 or no or false */
1134                        opts->numtail = 1;      /* negated option */
1135                        break;
1136                case Opt_nonumtail_yes:         /* empty or 1 or yes or true */
1137                        opts->numtail = 0;      /* negated option */
1138                        break;
1139                case Opt_rodir:
1140                        opts->rodir = 1;
1141                        break;
1142                case Opt_discard:
1143                        opts->discard = 1;
1144                        break;
1145
1146                /* obsolete mount options */
1147                case Opt_obsolete:
1148                        fat_msg(sb, KERN_INFO, "\"%s\" option is obsolete, "
1149                               "not supported now", p);
1150                        break;
1151                /* unknown option */
1152                default:
1153                        if (!silent) {
1154                                fat_msg(sb, KERN_ERR,
1155                                       "Unrecognized mount option \"%s\" "
1156                                       "or missing value", p);
1157                        }
1158                        return -EINVAL;
1159                }
1160        }
1161
1162out:
1163        /* UTF-8 doesn't provide FAT semantics */
1164        if (!strcmp(opts->iocharset, "utf8")) {
1165                fat_msg(sb, KERN_WARNING, "utf8 is not a recommended IO charset"
1166                       " for FAT filesystems, filesystem will be "
1167                       "case sensitive!");
1168        }
1169
1170        /* If user doesn't specify allow_utime, it's initialized from dmask. */
1171        if (opts->allow_utime == (unsigned short)-1)
1172                opts->allow_utime = ~opts->fs_dmask & (S_IWGRP | S_IWOTH);
1173        if (opts->unicode_xlate)
1174                opts->utf8 = 0;
1175
1176        return 0;
1177}
1178
1179static int fat_read_root(struct inode *inode)
1180{
1181        struct super_block *sb = inode->i_sb;
1182        struct msdos_sb_info *sbi = MSDOS_SB(sb);
1183        int error;
1184
1185        MSDOS_I(inode)->i_pos = 0;
1186        inode->i_uid = sbi->options.fs_uid;
1187        inode->i_gid = sbi->options.fs_gid;
1188        inode->i_version++;
1189        inode->i_generation = 0;
1190        inode->i_mode = fat_make_mode(sbi, ATTR_DIR, S_IRWXUGO);
1191        inode->i_op = sbi->dir_ops;
1192        inode->i_fop = &fat_dir_operations;
1193        if (sbi->fat_bits == 32) {
1194                MSDOS_I(inode)->i_start = sbi->root_cluster;
1195                error = fat_calc_dir_size(inode);
1196                if (error < 0)
1197                        return error;
1198        } else {
1199                MSDOS_I(inode)->i_start = 0;
1200                inode->i_size = sbi->dir_entries * sizeof(struct msdos_dir_entry);
1201        }
1202        inode->i_blocks = ((inode->i_size + (sbi->cluster_size - 1))
1203                           & ~((loff_t)sbi->cluster_size - 1)) >> 9;
1204        MSDOS_I(inode)->i_logstart = 0;
1205        MSDOS_I(inode)->mmu_private = inode->i_size;
1206
1207        fat_save_attrs(inode, ATTR_DIR);
1208        inode->i_mtime.tv_sec = inode->i_atime.tv_sec = inode->i_ctime.tv_sec = 0;
1209        inode->i_mtime.tv_nsec = inode->i_atime.tv_nsec = inode->i_ctime.tv_nsec = 0;
1210        set_nlink(inode, fat_subdirs(inode)+2);
1211
1212        return 0;
1213}
1214
1215/*
1216 * Read the super block of an MS-DOS FS.
1217 */
1218int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat,
1219                   void (*setup)(struct super_block *))
1220{
1221        struct inode *root_inode = NULL, *fat_inode = NULL;
1222        struct inode *fsinfo_inode = NULL;
1223        struct buffer_head *bh;
1224        struct fat_boot_sector *b;
1225        struct msdos_sb_info *sbi;
1226        u16 logical_sector_size;
1227        u32 total_sectors, total_clusters, fat_clusters, rootdir_sectors;
1228        int debug;
1229        unsigned int media;
1230        long error;
1231        char buf[50];
1232
1233        /*
1234         * GFP_KERNEL is ok here, because while we do hold the
1235         * supeblock lock, memory pressure can't call back into
1236         * the filesystem, since we're only just about to mount
1237         * it and have no inodes etc active!
1238         */
1239        sbi = kzalloc(sizeof(struct msdos_sb_info), GFP_KERNEL);
1240        if (!sbi)
1241                return -ENOMEM;
1242        sb->s_fs_info = sbi;
1243
1244        sb->s_flags |= MS_NODIRATIME;
1245        sb->s_magic = MSDOS_SUPER_MAGIC;
1246        sb->s_op = &fat_sops;
1247        sb->s_export_op = &fat_export_ops;
1248        ratelimit_state_init(&sbi->ratelimit, DEFAULT_RATELIMIT_INTERVAL,
1249                             DEFAULT_RATELIMIT_BURST);
1250
1251        error = parse_options(sb, data, isvfat, silent, &debug, &sbi->options);
1252        if (error)
1253                goto out_fail;
1254
1255        setup(sb); /* flavour-specific stuff that needs options */
1256
1257        error = -EIO;
1258        sb_min_blocksize(sb, 512);
1259        bh = sb_bread(sb, 0);
1260        if (bh == NULL) {
1261                fat_msg(sb, KERN_ERR, "unable to read boot sector");
1262                goto out_fail;
1263        }
1264
1265        b = (struct fat_boot_sector *) bh->b_data;
1266        if (!b->reserved) {
1267                if (!silent)
1268                        fat_msg(sb, KERN_ERR, "bogus number of reserved sectors");
1269                brelse(bh);
1270                goto out_invalid;
1271        }
1272        if (!b->fats) {
1273                if (!silent)
1274                        fat_msg(sb, KERN_ERR, "bogus number of FAT structure");
1275                brelse(bh);
1276                goto out_invalid;
1277        }
1278
1279        /*
1280         * Earlier we checked here that b->secs_track and b->head are nonzero,
1281         * but it turns out valid FAT filesystems can have zero there.
1282         */
1283
1284        media = b->media;
1285        if (!fat_valid_media(media)) {
1286                if (!silent)
1287                        fat_msg(sb, KERN_ERR, "invalid media value (0x%02x)",
1288                               media);
1289                brelse(bh);
1290                goto out_invalid;
1291        }
1292        logical_sector_size = get_unaligned_le16(&b->sector_size);
1293        if (!is_power_of_2(logical_sector_size)
1294            || (logical_sector_size < 512)
1295            || (logical_sector_size > 4096)) {
1296                if (!silent)
1297                        fat_msg(sb, KERN_ERR, "bogus logical sector size %u",
1298                               logical_sector_size);
1299                brelse(bh);
1300                goto out_invalid;
1301        }
1302        sbi->sec_per_clus = b->sec_per_clus;
1303        if (!is_power_of_2(sbi->sec_per_clus)) {
1304                if (!silent)
1305                        fat_msg(sb, KERN_ERR, "bogus sectors per cluster %u",
1306                               sbi->sec_per_clus);
1307                brelse(bh);
1308                goto out_invalid;
1309        }
1310
1311        if (logical_sector_size < sb->s_blocksize) {
1312                fat_msg(sb, KERN_ERR, "logical sector size too small for device"
1313                       " (logical sector size = %u)", logical_sector_size);
1314                brelse(bh);
1315                goto out_fail;
1316        }
1317        if (logical_sector_size > sb->s_blocksize) {
1318                brelse(bh);
1319
1320                if (!sb_set_blocksize(sb, logical_sector_size)) {
1321                        fat_msg(sb, KERN_ERR, "unable to set blocksize %u",
1322                               logical_sector_size);
1323                        goto out_fail;
1324                }
1325                bh = sb_bread(sb, 0);
1326                if (bh == NULL) {
1327                        fat_msg(sb, KERN_ERR, "unable to read boot sector"
1328                               " (logical sector size = %lu)",
1329                               sb->s_blocksize);
1330                        goto out_fail;
1331                }
1332                b = (struct fat_boot_sector *) bh->b_data;
1333        }
1334
1335        sbi->cluster_size = sb->s_blocksize * sbi->sec_per_clus;
1336        sbi->cluster_bits = ffs(sbi->cluster_size) - 1;
1337        sbi->fats = b->fats;
1338        sbi->fat_bits = 0;              /* Don't know yet */
1339        sbi->fat_start = le16_to_cpu(b->reserved);
1340        sbi->fat_length = le16_to_cpu(b->fat_length);
1341        sbi->root_cluster = 0;
1342        sbi->free_clusters = -1;        /* Don't know yet */
1343        sbi->free_clus_valid = 0;
1344        sbi->prev_free = FAT_START_ENT;
1345        sb->s_maxbytes = 0xffffffff;
1346
1347        if (!sbi->fat_length && b->fat32_length) {
1348                struct fat_boot_fsinfo *fsinfo;
1349                struct buffer_head *fsinfo_bh;
1350
1351                /* Must be FAT32 */
1352                sbi->fat_bits = 32;
1353                sbi->fat_length = le32_to_cpu(b->fat32_length);
1354                sbi->root_cluster = le32_to_cpu(b->root_cluster);
1355
1356                /* MC - if info_sector is 0, don't multiply by 0 */
1357                sbi->fsinfo_sector = le16_to_cpu(b->info_sector);
1358                if (sbi->fsinfo_sector == 0)
1359                        sbi->fsinfo_sector = 1;
1360
1361                fsinfo_bh = sb_bread(sb, sbi->fsinfo_sector);
1362                if (fsinfo_bh == NULL) {
1363                        fat_msg(sb, KERN_ERR, "bread failed, FSINFO block"
1364                               " (sector = %lu)", sbi->fsinfo_sector);
1365                        brelse(bh);
1366                        goto out_fail;
1367                }
1368
1369                fsinfo = (struct fat_boot_fsinfo *)fsinfo_bh->b_data;
1370                if (!IS_FSINFO(fsinfo)) {
1371                        fat_msg(sb, KERN_WARNING, "Invalid FSINFO signature: "
1372                               "0x%08x, 0x%08x (sector = %lu)",
1373                               le32_to_cpu(fsinfo->signature1),
1374                               le32_to_cpu(fsinfo->signature2),
1375                               sbi->fsinfo_sector);
1376                } else {
1377                        if (sbi->options.usefree)
1378                                sbi->free_clus_valid = 1;
1379                        sbi->free_clusters = le32_to_cpu(fsinfo->free_clusters);
1380                        sbi->prev_free = le32_to_cpu(fsinfo->next_cluster);
1381                }
1382
1383                brelse(fsinfo_bh);
1384        }
1385
1386        sbi->dir_per_block = sb->s_blocksize / sizeof(struct msdos_dir_entry);
1387        sbi->dir_per_block_bits = ffs(sbi->dir_per_block) - 1;
1388
1389        sbi->dir_start = sbi->fat_start + sbi->fats * sbi->fat_length;
1390        sbi->dir_entries = get_unaligned_le16(&b->dir_entries);
1391        if (sbi->dir_entries & (sbi->dir_per_block - 1)) {
1392                if (!silent)
1393                        fat_msg(sb, KERN_ERR, "bogus directroy-entries per block"
1394                               " (%u)", sbi->dir_entries);
1395                brelse(bh);
1396                goto out_invalid;
1397        }
1398
1399        rootdir_sectors = sbi->dir_entries
1400                * sizeof(struct msdos_dir_entry) / sb->s_blocksize;
1401        sbi->data_start = sbi->dir_start + rootdir_sectors;
1402        total_sectors = get_unaligned_le16(&b->sectors);
1403        if (total_sectors == 0)
1404                total_sectors = le32_to_cpu(b->total_sect);
1405
1406        total_clusters = (total_sectors - sbi->data_start) / sbi->sec_per_clus;
1407
1408        if (sbi->fat_bits != 32)
1409                sbi->fat_bits = (total_clusters > MAX_FAT12) ? 16 : 12;
1410
1411        /* check that FAT table does not overflow */
1412        fat_clusters = sbi->fat_length * sb->s_blocksize * 8 / sbi->fat_bits;
1413        total_clusters = min(total_clusters, fat_clusters - FAT_START_ENT);
1414        if (total_clusters > MAX_FAT(sb)) {
1415                if (!silent)
1416                        fat_msg(sb, KERN_ERR, "count of clusters too big (%u)",
1417                               total_clusters);
1418                brelse(bh);
1419                goto out_invalid;
1420        }
1421
1422        sbi->max_cluster = total_clusters + FAT_START_ENT;
1423        /* check the free_clusters, it's not necessarily correct */
1424        if (sbi->free_clusters != -1 && sbi->free_clusters > total_clusters)
1425                sbi->free_clusters = -1;
1426        /* check the prev_free, it's not necessarily correct */
1427        sbi->prev_free %= sbi->max_cluster;
1428        if (sbi->prev_free < FAT_START_ENT)
1429                sbi->prev_free = FAT_START_ENT;
1430
1431        brelse(bh);
1432
1433        /* set up enough so that it can read an inode */
1434        fat_hash_init(sb);
1435        fat_ent_access_init(sb);
1436
1437        /*
1438         * The low byte of FAT's first entry must have same value with
1439         * media-field.  But in real world, too many devices is
1440         * writing wrong value.  So, removed that validity check.
1441         *
1442         * if (FAT_FIRST_ENT(sb, media) != first)
1443         */
1444
1445        error = -EINVAL;
1446        sprintf(buf, "cp%d", sbi->options.codepage);
1447        sbi->nls_disk = load_nls(buf);
1448        if (!sbi->nls_disk) {
1449                fat_msg(sb, KERN_ERR, "codepage %s not found", buf);
1450                goto out_fail;
1451        }
1452
1453        /* FIXME: utf8 is using iocharset for upper/lower conversion */
1454        if (sbi->options.isvfat) {
1455                sbi->nls_io = load_nls(sbi->options.iocharset);
1456                if (!sbi->nls_io) {
1457                        fat_msg(sb, KERN_ERR, "IO charset %s not found",
1458                               sbi->options.iocharset);
1459                        goto out_fail;
1460                }
1461        }
1462
1463        error = -ENOMEM;
1464        fat_inode = new_inode(sb);
1465        if (!fat_inode)
1466                goto out_fail;
1467        MSDOS_I(fat_inode)->i_pos = 0;
1468        sbi->fat_inode = fat_inode;
1469
1470        fsinfo_inode = new_inode(sb);
1471        if (!fsinfo_inode)
1472                goto out_fail;
1473        fsinfo_inode->i_ino = MSDOS_FSINFO_INO;
1474        sbi->fsinfo_inode = fsinfo_inode;
1475        insert_inode_hash(fsinfo_inode);
1476
1477        root_inode = new_inode(sb);
1478        if (!root_inode)
1479                goto out_fail;
1480        root_inode->i_ino = MSDOS_ROOT_INO;
1481        root_inode->i_version = 1;
1482        error = fat_read_root(root_inode);
1483        if (error < 0) {
1484                iput(root_inode);
1485                goto out_fail;
1486        }
1487        error = -ENOMEM;
1488        insert_inode_hash(root_inode);
1489        sb->s_root = d_make_root(root_inode);
1490        if (!sb->s_root) {
1491                fat_msg(sb, KERN_ERR, "get root inode failed");
1492                goto out_fail;
1493        }
1494
1495        return 0;
1496
1497out_invalid:
1498        error = -EINVAL;
1499        if (!silent)
1500                fat_msg(sb, KERN_INFO, "Can't find a valid FAT filesystem");
1501
1502out_fail:
1503        if (fsinfo_inode)
1504                iput(fsinfo_inode);
1505        if (fat_inode)
1506                iput(fat_inode);
1507        unload_nls(sbi->nls_io);
1508        unload_nls(sbi->nls_disk);
1509        if (sbi->options.iocharset != fat_default_iocharset)
1510                kfree(sbi->options.iocharset);
1511        sb->s_fs_info = NULL;
1512        kfree(sbi);
1513        return error;
1514}
1515
1516EXPORT_SYMBOL_GPL(fat_fill_super);
1517
1518/*
1519 * helper function for fat_flush_inodes.  This writes both the inode
1520 * and the file data blocks, waiting for in flight data blocks before
1521 * the start of the call.  It does not wait for any io started
1522 * during the call
1523 */
1524static int writeback_inode(struct inode *inode)
1525{
1526
1527        int ret;
1528        struct address_space *mapping = inode->i_mapping;
1529        struct writeback_control wbc = {
1530               .sync_mode = WB_SYNC_NONE,
1531              .nr_to_write = 0,
1532        };
1533        /* if we used WB_SYNC_ALL, sync_inode waits for the io for the
1534        * inode to finish.  So WB_SYNC_NONE is sent down to sync_inode
1535        * and filemap_fdatawrite is used for the data blocks
1536        */
1537        ret = sync_inode(inode, &wbc);
1538        if (!ret)
1539               ret = filemap_fdatawrite(mapping);
1540        return ret;
1541}
1542
1543/*
1544 * write data and metadata corresponding to i1 and i2.  The io is
1545 * started but we do not wait for any of it to finish.
1546 *
1547 * filemap_flush is used for the block device, so if there is a dirty
1548 * page for a block already in flight, we will not wait and start the
1549 * io over again
1550 */
1551int fat_flush_inodes(struct super_block *sb, struct inode *i1, struct inode *i2)
1552{
1553        int ret = 0;
1554        if (!MSDOS_SB(sb)->options.flush)
1555                return 0;
1556        if (i1)
1557                ret = writeback_inode(i1);
1558        if (!ret && i2)
1559                ret = writeback_inode(i2);
1560        if (!ret) {
1561                struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping;
1562                ret = filemap_flush(mapping);
1563        }
1564        return ret;
1565}
1566EXPORT_SYMBOL_GPL(fat_flush_inodes);
1567
1568static int __init init_fat_fs(void)
1569{
1570        int err;
1571
1572        err = fat_cache_init();
1573        if (err)
1574                return err;
1575
1576        err = fat_init_inodecache();
1577        if (err)
1578                goto failed;
1579
1580        return 0;
1581
1582failed:
1583        fat_cache_destroy();
1584        return err;
1585}
1586
1587static void __exit exit_fat_fs(void)
1588{
1589        fat_cache_destroy();
1590        fat_destroy_inodecache();
1591}
1592
1593module_init(init_fat_fs)
1594module_exit(exit_fat_fs)
1595
1596MODULE_LICENSE("GPL");
1597
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