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
 284static void dir_hash_init(struct super_block *sb)
 285{
 286        struct msdos_sb_info *sbi = MSDOS_SB(sb);
 287        int i;
 288
 289        spin_lock_init(&sbi->dir_hash_lock);
 290        for (i = 0; i < FAT_HASH_SIZE; i++)
 291                INIT_HLIST_HEAD(&sbi->dir_hashtable[i]);
 292}
 293
 294void fat_attach(struct inode *inode, loff_t i_pos)
 295{
 296        struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 297
 298        if (inode->i_ino != MSDOS_ROOT_INO) {
 299                struct hlist_head *head =   sbi->inode_hashtable
 300                                          + fat_hash(i_pos);
 301
 302                spin_lock(&sbi->inode_hash_lock);
 303                MSDOS_I(inode)->i_pos = i_pos;
 304                hlist_add_head(&MSDOS_I(inode)->i_fat_hash, head);
 305                spin_unlock(&sbi->inode_hash_lock);
 306        }
 307
 308        /* If NFS support is enabled, cache the mapping of start cluster
 309         * to directory inode. This is used during reconnection of
 310         * dentries to the filesystem root.
 311         */
 312        if (S_ISDIR(inode->i_mode) && sbi->options.nfs) {
 313                struct hlist_head *d_head = sbi->dir_hashtable;
 314                d_head += fat_dir_hash(MSDOS_I(inode)->i_logstart);
 315
 316                spin_lock(&sbi->dir_hash_lock);
 317                hlist_add_head(&MSDOS_I(inode)->i_dir_hash, d_head);
 318                spin_unlock(&sbi->dir_hash_lock);
 319        }
 320}
 321EXPORT_SYMBOL_GPL(fat_attach);
 322
 323void fat_detach(struct inode *inode)
 324{
 325        struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 326        spin_lock(&sbi->inode_hash_lock);
 327        MSDOS_I(inode)->i_pos = 0;
 328        hlist_del_init(&MSDOS_I(inode)->i_fat_hash);
 329        spin_unlock(&sbi->inode_hash_lock);
 330
 331        if (S_ISDIR(inode->i_mode) && sbi->options.nfs) {
 332                spin_lock(&sbi->dir_hash_lock);
 333                hlist_del_init(&MSDOS_I(inode)->i_dir_hash);
 334                spin_unlock(&sbi->dir_hash_lock);
 335        }
 336}
 337EXPORT_SYMBOL_GPL(fat_detach);
 338
 339struct inode *fat_iget(struct super_block *sb, loff_t i_pos)
 340{
 341        struct msdos_sb_info *sbi = MSDOS_SB(sb);
 342        struct hlist_head *head = sbi->inode_hashtable + fat_hash(i_pos);
 343        struct hlist_node *_p;
 344        struct msdos_inode_info *i;
 345        struct inode *inode = NULL;
 346
 347        spin_lock(&sbi->inode_hash_lock);
 348        hlist_for_each_entry(i, _p, head, i_fat_hash) {
 349                BUG_ON(i->vfs_inode.i_sb != sb);
 350                if (i->i_pos != i_pos)
 351                        continue;
 352                inode = igrab(&i->vfs_inode);
 353                if (inode)
 354                        break;
 355        }
 356        spin_unlock(&sbi->inode_hash_lock);
 357        return inode;
 358}
 359
 360static int is_exec(unsigned char *extension)
 361{
 362        unsigned char *exe_extensions = "EXECOMBAT", *walk;
 363
 364        for (walk = exe_extensions; *walk; walk += 3)
 365                if (!strncmp(extension, walk, 3))
 366                        return 1;
 367        return 0;
 368}
 369
 370static int fat_calc_dir_size(struct inode *inode)
 371{
 372        struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 373        int ret, fclus, dclus;
 374
 375        inode->i_size = 0;
 376        if (MSDOS_I(inode)->i_start == 0)
 377                return 0;
 378
 379        ret = fat_get_cluster(inode, FAT_ENT_EOF, &fclus, &dclus);
 380        if (ret < 0)
 381                return ret;
 382        inode->i_size = (fclus + 1) << sbi->cluster_bits;
 383
 384        return 0;
 385}
 386
 387/* doesn't deal with root inode */
 388static int fat_fill_inode(struct inode *inode, struct msdos_dir_entry *de)
 389{
 390        struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 391        int error;
 392
 393        MSDOS_I(inode)->i_pos = 0;
 394        inode->i_uid = sbi->options.fs_uid;
 395        inode->i_gid = sbi->options.fs_gid;
 396        inode->i_version++;
 397        inode->i_generation = get_seconds();
 398
 399        if ((de->attr & ATTR_DIR) && !IS_FREE(de->name)) {
 400                inode->i_generation &= ~1;
 401                inode->i_mode = fat_make_mode(sbi, de->attr, S_IRWXUGO);
 402                inode->i_op = sbi->dir_ops;
 403                inode->i_fop = &fat_dir_operations;
 404
 405                MSDOS_I(inode)->i_start = fat_get_start(sbi, de);
 406                MSDOS_I(inode)->i_logstart = MSDOS_I(inode)->i_start;
 407                error = fat_calc_dir_size(inode);
 408                if (error < 0)
 409                        return error;
 410                MSDOS_I(inode)->mmu_private = inode->i_size;
 411
 412                set_nlink(inode, fat_subdirs(inode));
 413        } else { /* not a directory */
 414                inode->i_generation |= 1;
 415                inode->i_mode = fat_make_mode(sbi, de->attr,
 416                        ((sbi->options.showexec && !is_exec(de->name + 8))
 417                         ? S_IRUGO|S_IWUGO : S_IRWXUGO));
 418                MSDOS_I(inode)->i_start = fat_get_start(sbi, de);
 419
 420                MSDOS_I(inode)->i_logstart = MSDOS_I(inode)->i_start;
 421                inode->i_size = le32_to_cpu(de->size);
 422                inode->i_op = &fat_file_inode_operations;
 423                inode->i_fop = &fat_file_operations;
 424                inode->i_mapping->a_ops = &fat_aops;
 425                MSDOS_I(inode)->mmu_private = inode->i_size;
 426        }
 427        if (de->attr & ATTR_SYS) {
 428                if (sbi->options.sys_immutable)
 429                        inode->i_flags |= S_IMMUTABLE;
 430        }
 431        fat_save_attrs(inode, de->attr);
 432
 433        inode->i_blocks = ((inode->i_size + (sbi->cluster_size - 1))
 434                           & ~((loff_t)sbi->cluster_size - 1)) >> 9;
 435
 436        fat_time_fat2unix(sbi, &inode->i_mtime, de->time, de->date, 0);
 437        if (sbi->options.isvfat) {
 438                fat_time_fat2unix(sbi, &inode->i_ctime, de->ctime,
 439                                  de->cdate, de->ctime_cs);
 440                fat_time_fat2unix(sbi, &inode->i_atime, 0, de->adate, 0);
 441        } else
 442                inode->i_ctime = inode->i_atime = inode->i_mtime;
 443
 444        return 0;
 445}
 446
 447struct inode *fat_build_inode(struct super_block *sb,
 448                        struct msdos_dir_entry *de, loff_t i_pos)
 449{
 450        struct inode *inode;
 451        int err;
 452
 453        inode = fat_iget(sb, i_pos);
 454        if (inode)
 455                goto out;
 456        inode = new_inode(sb);
 457        if (!inode) {
 458                inode = ERR_PTR(-ENOMEM);
 459                goto out;
 460        }
 461        inode->i_ino = iunique(sb, MSDOS_ROOT_INO);
 462        inode->i_version = 1;
 463        err = fat_fill_inode(inode, de);
 464        if (err) {
 465                iput(inode);
 466                inode = ERR_PTR(err);
 467                goto out;
 468        }
 469        fat_attach(inode, i_pos);
 470        insert_inode_hash(inode);
 471out:
 472        return inode;
 473}
 474
 475EXPORT_SYMBOL_GPL(fat_build_inode);
 476
 477static void fat_evict_inode(struct inode *inode)
 478{
 479        truncate_inode_pages(&inode->i_data, 0);
 480        if (!inode->i_nlink) {
 481                inode->i_size = 0;
 482                fat_truncate_blocks(inode, 0);
 483        }
 484        invalidate_inode_buffers(inode);
 485        clear_inode(inode);
 486        fat_cache_inval_inode(inode);
 487        fat_detach(inode);
 488}
 489
 490static void fat_put_super(struct super_block *sb)
 491{
 492        struct msdos_sb_info *sbi = MSDOS_SB(sb);
 493
 494        iput(sbi->fsinfo_inode);
 495        iput(sbi->fat_inode);
 496
 497        unload_nls(sbi->nls_disk);
 498        unload_nls(sbi->nls_io);
 499
 500        if (sbi->options.iocharset != fat_default_iocharset)
 501                kfree(sbi->options.iocharset);
 502
 503        sb->s_fs_info = NULL;
 504        kfree(sbi);
 505}
 506
 507static struct kmem_cache *fat_inode_cachep;
 508
 509static struct inode *fat_alloc_inode(struct super_block *sb)
 510{
 511        struct msdos_inode_info *ei;
 512        ei = kmem_cache_alloc(fat_inode_cachep, GFP_NOFS);
 513        if (!ei)
 514                return NULL;
 515
 516        init_rwsem(&ei->truncate_lock);
 517        return &ei->vfs_inode;
 518}
 519
 520static void fat_i_callback(struct rcu_head *head)
 521{
 522        struct inode *inode = container_of(head, struct inode, i_rcu);
 523        kmem_cache_free(fat_inode_cachep, MSDOS_I(inode));
 524}
 525
 526static void fat_destroy_inode(struct inode *inode)
 527{
 528        call_rcu(&inode->i_rcu, fat_i_callback);
 529}
 530
 531static void init_once(void *foo)
 532{
 533        struct msdos_inode_info *ei = (struct msdos_inode_info *)foo;
 534
 535        spin_lock_init(&ei->cache_lru_lock);
 536        ei->nr_caches = 0;
 537        ei->cache_valid_id = FAT_CACHE_VALID + 1;
 538        INIT_LIST_HEAD(&ei->cache_lru);
 539        INIT_HLIST_NODE(&ei->i_fat_hash);
 540        INIT_HLIST_NODE(&ei->i_dir_hash);
 541        inode_init_once(&ei->vfs_inode);
 542}
 543
 544static int __init fat_init_inodecache(void)
 545{
 546        fat_inode_cachep = kmem_cache_create("fat_inode_cache",
 547                                             sizeof(struct msdos_inode_info),
 548                                             0, (SLAB_RECLAIM_ACCOUNT|
 549                                                SLAB_MEM_SPREAD),
 550                                             init_once);
 551        if (fat_inode_cachep == NULL)
 552                return -ENOMEM;
 553        return 0;
 554}
 555
 556static void __exit fat_destroy_inodecache(void)
 557{
 558        /*
 559         * Make sure all delayed rcu free inodes are flushed before we
 560         * destroy cache.
 561         */
 562        rcu_barrier();
 563        kmem_cache_destroy(fat_inode_cachep);
 564}
 565
 566static int fat_remount(struct super_block *sb, int *flags, char *data)
 567{
 568        struct msdos_sb_info *sbi = MSDOS_SB(sb);
 569        *flags |= MS_NODIRATIME | (sbi->options.isvfat ? 0 : MS_NOATIME);
 570        return 0;
 571}
 572
 573static int fat_statfs(struct dentry *dentry, struct kstatfs *buf)
 574{
 575        struct super_block *sb = dentry->d_sb;
 576        struct msdos_sb_info *sbi = MSDOS_SB(sb);
 577        u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
 578
 579        /* If the count of free cluster is still unknown, counts it here. */
 580        if (sbi->free_clusters == -1 || !sbi->free_clus_valid) {
 581                int err = fat_count_free_clusters(dentry->d_sb);
 582                if (err)
 583                        return err;
 584        }
 585
 586        buf->f_type = dentry->d_sb->s_magic;
 587        buf->f_bsize = sbi->cluster_size;
 588        buf->f_blocks = sbi->max_cluster - FAT_START_ENT;
 589        buf->f_bfree = sbi->free_clusters;
 590        buf->f_bavail = sbi->free_clusters;
 591        buf->f_fsid.val[0] = (u32)id;
 592        buf->f_fsid.val[1] = (u32)(id >> 32);
 593        buf->f_namelen =
 594                (sbi->options.isvfat ? FAT_LFN_LEN : 12) * NLS_MAX_CHARSET_SIZE;
 595
 596        return 0;
 597}
 598
 599static inline loff_t fat_i_pos_read(struct msdos_sb_info *sbi,
 600                                    struct inode *inode)
 601{
 602        loff_t i_pos;
 603#if BITS_PER_LONG == 32
 604        spin_lock(&sbi->inode_hash_lock);
 605#endif
 606        i_pos = MSDOS_I(inode)->i_pos;
 607#if BITS_PER_LONG == 32
 608        spin_unlock(&sbi->inode_hash_lock);
 609#endif
 610        return i_pos;
 611}
 612
 613static int __fat_write_inode(struct inode *inode, int wait)
 614{
 615        struct super_block *sb = inode->i_sb;
 616        struct msdos_sb_info *sbi = MSDOS_SB(sb);
 617        struct buffer_head *bh;
 618        struct msdos_dir_entry *raw_entry;
 619        loff_t i_pos;
 620        int err;
 621
 622        if (inode->i_ino == MSDOS_ROOT_INO)
 623                return 0;
 624
 625retry:
 626        i_pos = fat_i_pos_read(sbi, inode);
 627        if (!i_pos)
 628                return 0;
 629
 630        bh = sb_bread(sb, i_pos >> sbi->dir_per_block_bits);
 631        if (!bh) {
 632                fat_msg(sb, KERN_ERR, "unable to read inode block "
 633                       "for updating (i_pos %lld)", i_pos);
 634                return -EIO;
 635        }
 636        spin_lock(&sbi->inode_hash_lock);
 637        if (i_pos != MSDOS_I(inode)->i_pos) {
 638                spin_unlock(&sbi->inode_hash_lock);
 639                brelse(bh);
 640                goto retry;
 641        }
 642
 643        raw_entry = &((struct msdos_dir_entry *) (bh->b_data))
 644            [i_pos & (sbi->dir_per_block - 1)];
 645        if (S_ISDIR(inode->i_mode))
 646                raw_entry->size = 0;
 647        else
 648                raw_entry->size = cpu_to_le32(inode->i_size);
 649        raw_entry->attr = fat_make_attrs(inode);
 650        fat_set_start(raw_entry, MSDOS_I(inode)->i_logstart);
 651        fat_time_unix2fat(sbi, &inode->i_mtime, &raw_entry->time,
 652                          &raw_entry->date, NULL);
 653        if (sbi->options.isvfat) {
 654                __le16 atime;
 655                fat_time_unix2fat(sbi, &inode->i_ctime, &raw_entry->ctime,
 656                                  &raw_entry->cdate, &raw_entry->ctime_cs);
 657                fat_time_unix2fat(sbi, &inode->i_atime, &atime,
 658                                  &raw_entry->adate, NULL);
 659        }
 660        spin_unlock(&sbi->inode_hash_lock);
 661        mark_buffer_dirty(bh);
 662        err = 0;
 663        if (wait)
 664                err = sync_dirty_buffer(bh);
 665        brelse(bh);
 666        return err;
 667}
 668
 669static int fat_write_inode(struct inode *inode, struct writeback_control *wbc)
 670{
 671        int err;
 672
 673        if (inode->i_ino == MSDOS_FSINFO_INO) {
 674                struct super_block *sb = inode->i_sb;
 675
 676                mutex_lock(&MSDOS_SB(sb)->s_lock);
 677                err = fat_clusters_flush(sb);
 678                mutex_unlock(&MSDOS_SB(sb)->s_lock);
 679        } else
 680                err = __fat_write_inode(inode, wbc->sync_mode == WB_SYNC_ALL);
 681
 682        return err;
 683}
 684
 685int fat_sync_inode(struct inode *inode)
 686{
 687        return __fat_write_inode(inode, 1);
 688}
 689
 690EXPORT_SYMBOL_GPL(fat_sync_inode);
 691
 692static int fat_show_options(struct seq_file *m, struct dentry *root);
 693static const struct super_operations fat_sops = {
 694        .alloc_inode    = fat_alloc_inode,
 695        .destroy_inode  = fat_destroy_inode,
 696        .write_inode    = fat_write_inode,
 697        .evict_inode    = fat_evict_inode,
 698        .put_super      = fat_put_super,
 699        .statfs         = fat_statfs,
 700        .remount_fs     = fat_remount,
 701
 702        .show_options   = fat_show_options,
 703};
 704
 705static const struct export_operations fat_export_ops = {
 706        .fh_to_dentry   = fat_fh_to_dentry,
 707        .fh_to_parent   = fat_fh_to_parent,
 708        .get_parent     = fat_get_parent,
 709};
 710
 711static int fat_show_options(struct seq_file *m, struct dentry *root)
 712{
 713        struct msdos_sb_info *sbi = MSDOS_SB(root->d_sb);
 714        struct fat_mount_options *opts = &sbi->options;
 715        int isvfat = opts->isvfat;
 716
 717        if (!uid_eq(opts->fs_uid, GLOBAL_ROOT_UID))
 718                seq_printf(m, ",uid=%u",
 719                                from_kuid_munged(&init_user_ns, opts->fs_uid));
 720        if (!gid_eq(opts->fs_gid, GLOBAL_ROOT_GID))
 721                seq_printf(m, ",gid=%u",
 722                                from_kgid_munged(&init_user_ns, opts->fs_gid));
 723        seq_printf(m, ",fmask=%04o", opts->fs_fmask);
 724        seq_printf(m, ",dmask=%04o", opts->fs_dmask);
 725        if (opts->allow_utime)
 726                seq_printf(m, ",allow_utime=%04o", opts->allow_utime);
 727        if (sbi->nls_disk)
 728                seq_printf(m, ",codepage=%s", sbi->nls_disk->charset);
 729        if (isvfat) {
 730                if (sbi->nls_io)
 731                        seq_printf(m, ",iocharset=%s", sbi->nls_io->charset);
 732
 733                switch (opts->shortname) {
 734                case VFAT_SFN_DISPLAY_WIN95 | VFAT_SFN_CREATE_WIN95:
 735                        seq_puts(m, ",shortname=win95");
 736                        break;
 737                case VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WINNT:
 738                        seq_puts(m, ",shortname=winnt");
 739                        break;
 740                case VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WIN95:
 741                        seq_puts(m, ",shortname=mixed");
 742                        break;
 743                case VFAT_SFN_DISPLAY_LOWER | VFAT_SFN_CREATE_WIN95:
 744                        seq_puts(m, ",shortname=lower");
 745                        break;
 746                default:
 747                        seq_puts(m, ",shortname=unknown");
 748                        break;
 749                }
 750        }
 751        if (opts->name_check != 'n')
 752                seq_printf(m, ",check=%c", opts->name_check);
 753        if (opts->usefree)
 754                seq_puts(m, ",usefree");
 755        if (opts->quiet)
 756                seq_puts(m, ",quiet");
 757        if (opts->nfs)
 758                seq_puts(m, ",nfs");
 759        if (opts->showexec)
 760                seq_puts(m, ",showexec");
 761        if (opts->sys_immutable)
 762                seq_puts(m, ",sys_immutable");
 763        if (!isvfat) {
 764                if (opts->dotsOK)
 765                        seq_puts(m, ",dotsOK=yes");
 766                if (opts->nocase)
 767                        seq_puts(m, ",nocase");
 768        } else {
 769                if (opts->utf8)
 770                        seq_puts(m, ",utf8");
 771                if (opts->unicode_xlate)
 772                        seq_puts(m, ",uni_xlate");
 773                if (!opts->numtail)
 774                        seq_puts(m, ",nonumtail");
 775                if (opts->rodir)
 776                        seq_puts(m, ",rodir");
 777        }
 778        if (opts->flush)
 779                seq_puts(m, ",flush");
 780        if (opts->tz_utc)
 781                seq_puts(m, ",tz=UTC");
 782        if (opts->errors == FAT_ERRORS_CONT)
 783                seq_puts(m, ",errors=continue");
 784        else if (opts->errors == FAT_ERRORS_PANIC)
 785                seq_puts(m, ",errors=panic");
 786        else
 787                seq_puts(m, ",errors=remount-ro");
 788        if (opts->discard)
 789                seq_puts(m, ",discard");
 790
 791        return 0;
 792}
 793
 794enum {
 795        Opt_check_n, Opt_check_r, Opt_check_s, Opt_uid, Opt_gid,
 796        Opt_umask, Opt_dmask, Opt_fmask, Opt_allow_utime, Opt_codepage,
 797        Opt_usefree, Opt_nocase, Opt_quiet, Opt_showexec, Opt_debug,
 798        Opt_immutable, Opt_dots, Opt_nodots,
 799        Opt_charset, Opt_shortname_lower, Opt_shortname_win95,
 800        Opt_shortname_winnt, Opt_shortname_mixed, Opt_utf8_no, Opt_utf8_yes,
 801        Opt_uni_xl_no, Opt_uni_xl_yes, Opt_nonumtail_no, Opt_nonumtail_yes,
 802        Opt_obsolete, Opt_flush, Opt_tz_utc, Opt_rodir, Opt_err_cont,
 803        Opt_err_panic, Opt_err_ro, Opt_discard, Opt_nfs, Opt_err,
 804};
 805
 806static const match_table_t fat_tokens = {
 807        {Opt_check_r, "check=relaxed"},
 808        {Opt_check_s, "check=strict"},
 809        {Opt_check_n, "check=normal"},
 810        {Opt_check_r, "check=r"},
 811        {Opt_check_s, "check=s"},
 812        {Opt_check_n, "check=n"},
 813        {Opt_uid, "uid=%u"},
 814        {Opt_gid, "gid=%u"},
 815        {Opt_umask, "umask=%o"},
 816        {Opt_dmask, "dmask=%o"},
 817        {Opt_fmask, "fmask=%o"},
 818        {Opt_allow_utime, "allow_utime=%o"},
 819        {Opt_codepage, "codepage=%u"},
 820        {Opt_usefree, "usefree"},
 821        {Opt_nocase, "nocase"},
 822        {Opt_quiet, "quiet"},
 823        {Opt_showexec, "showexec"},
 824        {Opt_debug, "debug"},
 825        {Opt_immutable, "sys_immutable"},
 826        {Opt_flush, "flush"},
 827        {Opt_tz_utc, "tz=UTC"},
 828        {Opt_err_cont, "errors=continue"},
 829        {Opt_err_panic, "errors=panic"},
 830        {Opt_err_ro, "errors=remount-ro"},
 831        {Opt_discard, "discard"},
 832        {Opt_nfs, "nfs"},
 833        {Opt_obsolete, "conv=binary"},
 834        {Opt_obsolete, "conv=text"},
 835        {Opt_obsolete, "conv=auto"},
 836        {Opt_obsolete, "conv=b"},
 837        {Opt_obsolete, "conv=t"},
 838        {Opt_obsolete, "conv=a"},
 839        {Opt_obsolete, "fat=%u"},
 840        {Opt_obsolete, "blocksize=%u"},
 841        {Opt_obsolete, "cvf_format=%20s"},
 842        {Opt_obsolete, "cvf_options=%100s"},
 843        {Opt_obsolete, "posix"},
 844        {Opt_err, NULL},
 845};
 846static const match_table_t msdos_tokens = {
 847        {Opt_nodots, "nodots"},
 848        {Opt_nodots, "dotsOK=no"},
 849        {Opt_dots, "dots"},
 850        {Opt_dots, "dotsOK=yes"},
 851        {Opt_err, NULL}
 852};
 853static const match_table_t vfat_tokens = {
 854        {Opt_charset, "iocharset=%s"},
 855        {Opt_shortname_lower, "shortname=lower"},
 856        {Opt_shortname_win95, "shortname=win95"},
 857        {Opt_shortname_winnt, "shortname=winnt"},
 858        {Opt_shortname_mixed, "shortname=mixed"},
 859        {Opt_utf8_no, "utf8=0"},                /* 0 or no or false */
 860        {Opt_utf8_no, "utf8=no"},
 861        {Opt_utf8_no, "utf8=false"},
 862        {Opt_utf8_yes, "utf8=1"},               /* empty or 1 or yes or true */
 863        {Opt_utf8_yes, "utf8=yes"},
 864        {Opt_utf8_yes, "utf8=true"},
 865        {Opt_utf8_yes, "utf8"},
 866        {Opt_uni_xl_no, "uni_xlate=0"},         /* 0 or no or false */
 867        {Opt_uni_xl_no, "uni_xlate=no"},
 868        {Opt_uni_xl_no, "uni_xlate=false"},
 869        {Opt_uni_xl_yes, "uni_xlate=1"},        /* empty or 1 or yes or true */
 870        {Opt_uni_xl_yes, "uni_xlate=yes"},
 871        {Opt_uni_xl_yes, "uni_xlate=true"},
 872        {Opt_uni_xl_yes, "uni_xlate"},
 873        {Opt_nonumtail_no, "nonumtail=0"},      /* 0 or no or false */
 874        {Opt_nonumtail_no, "nonumtail=no"},
 875        {Opt_nonumtail_no, "nonumtail=false"},
 876        {Opt_nonumtail_yes, "nonumtail=1"},     /* empty or 1 or yes or true */
 877        {Opt_nonumtail_yes, "nonumtail=yes"},
 878        {Opt_nonumtail_yes, "nonumtail=true"},
 879        {Opt_nonumtail_yes, "nonumtail"},
 880        {Opt_rodir, "rodir"},
 881        {Opt_err, NULL}
 882};
 883
 884static int parse_options(struct super_block *sb, char *options, int is_vfat,
 885                         int silent, int *debug, struct fat_mount_options *opts)
 886{
 887        char *p;
 888        substring_t args[MAX_OPT_ARGS];
 889        int option;
 890        char *iocharset;
 891
 892        opts->isvfat = is_vfat;
 893
 894        opts->fs_uid = current_uid();
 895        opts->fs_gid = current_gid();
 896        opts->fs_fmask = opts->fs_dmask = current_umask();
 897        opts->allow_utime = -1;
 898        opts->codepage = fat_default_codepage;
 899        opts->iocharset = fat_default_iocharset;
 900        if (is_vfat) {
 901                opts->shortname = VFAT_SFN_DISPLAY_WINNT|VFAT_SFN_CREATE_WIN95;
 902                opts->rodir = 0;
 903        } else {
 904                opts->shortname = 0;
 905                opts->rodir = 1;
 906        }
 907        opts->name_check = 'n';
 908        opts->quiet = opts->showexec = opts->sys_immutable = opts->dotsOK =  0;
 909        opts->utf8 = opts->unicode_xlate = 0;
 910        opts->numtail = 1;
 911        opts->usefree = opts->nocase = 0;
 912        opts->tz_utc = 0;
 913        opts->nfs = 0;
 914        opts->errors = FAT_ERRORS_RO;
 915        *debug = 0;
 916
 917        if (!options)
 918                goto out;
 919
 920        while ((p = strsep(&options, ",")) != NULL) {
 921                int token;
 922                if (!*p)
 923                        continue;
 924
 925                token = match_token(p, fat_tokens, args);
 926                if (token == Opt_err) {
 927                        if (is_vfat)
 928                                token = match_token(p, vfat_tokens, args);
 929                        else
 930                                token = match_token(p, msdos_tokens, args);
 931                }
 932                switch (token) {
 933                case Opt_check_s:
 934                        opts->name_check = 's';
 935                        break;
 936                case Opt_check_r:
 937                        opts->name_check = 'r';
 938                        break;
 939                case Opt_check_n:
 940                        opts->name_check = 'n';
 941                        break;
 942                case Opt_usefree:
 943                        opts->usefree = 1;
 944                        break;
 945                case Opt_nocase:
 946                        if (!is_vfat)
 947                                opts->nocase = 1;
 948                        else {
 949                                /* for backward compatibility */
 950                                opts->shortname = VFAT_SFN_DISPLAY_WIN95
 951                                        | VFAT_SFN_CREATE_WIN95;
 952                        }
 953                        break;
 954                case Opt_quiet:
 955                        opts->quiet = 1;
 956                        break;
 957                case Opt_showexec:
 958                        opts->showexec = 1;
 959                        break;
 960                case Opt_debug:
 961                        *debug = 1;
 962                        break;
 963                case Opt_immutable:
 964                        opts->sys_immutable = 1;
 965                        break;
 966                case Opt_uid:
 967                        if (match_int(&args[0], &option))
 968                                return 0;
 969                        opts->fs_uid = make_kuid(current_user_ns(), option);
 970                        if (!uid_valid(opts->fs_uid))
 971                                return 0;
 972                        break;
 973                case Opt_gid:
 974                        if (match_int(&args[0], &option))
 975                                return 0;
 976                        opts->fs_gid = make_kgid(current_user_ns(), option);
 977                        if (!gid_valid(opts->fs_gid))
 978                                return 0;
 979                        break;
 980                case Opt_umask:
 981                        if (match_octal(&args[0], &option))
 982                                return 0;
 983                        opts->fs_fmask = opts->fs_dmask = option;
 984                        break;
 985                case Opt_dmask:
 986                        if (match_octal(&args[0], &option))
 987                                return 0;
 988                        opts->fs_dmask = option;
 989                        break;
 990                case Opt_fmask:
 991                        if (match_octal(&args[0], &option))
 992                                return 0;
 993                        opts->fs_fmask = option;
 994                        break;
 995                case Opt_allow_utime:
 996                        if (match_octal(&args[0], &option))
 997                                return 0;
 998                        opts->allow_utime = option & (S_IWGRP | S_IWOTH);
 999                        break;
1000                case Opt_codepage:
1001                        if (match_int(&args[0], &option))
1002                                return 0;
1003                        opts->codepage = option;
1004                        break;
1005                case Opt_flush:
1006                        opts->flush = 1;
1007                        break;
1008                case Opt_tz_utc:
1009                        opts->tz_utc = 1;
1010                        break;
1011                case Opt_err_cont:
1012                        opts->errors = FAT_ERRORS_CONT;
1013                        break;
1014                case Opt_err_panic:
1015                        opts->errors = FAT_ERRORS_PANIC;
1016                        break;
1017                case Opt_err_ro:
1018                        opts->errors = FAT_ERRORS_RO;
1019                        break;
1020
1021                /* msdos specific */
1022                case Opt_dots:
1023                        opts->dotsOK = 1;
1024                        break;
1025                case Opt_nodots:
1026                        opts->dotsOK = 0;
1027                        break;
1028
1029                /* vfat specific */
1030                case Opt_charset:
1031                        if (opts->iocharset != fat_default_iocharset)
1032                                kfree(opts->iocharset);
1033                        iocharset = match_strdup(&args[0]);
1034                        if (!iocharset)
1035                                return -ENOMEM;
1036                        opts->iocharset = iocharset;
1037                        break;
1038                case Opt_shortname_lower:
1039                        opts->shortname = VFAT_SFN_DISPLAY_LOWER
1040                                        | VFAT_SFN_CREATE_WIN95;
1041                        break;
1042                case Opt_shortname_win95:
1043                        opts->shortname = VFAT_SFN_DISPLAY_WIN95
1044                                        | VFAT_SFN_CREATE_WIN95;
1045                        break;
1046                case Opt_shortname_winnt:
1047                        opts->shortname = VFAT_SFN_DISPLAY_WINNT
1048                                        | VFAT_SFN_CREATE_WINNT;
1049                        break;
1050                case Opt_shortname_mixed:
1051                        opts->shortname = VFAT_SFN_DISPLAY_WINNT
1052                                        | VFAT_SFN_CREATE_WIN95;
1053                        break;
1054                case Opt_utf8_no:               /* 0 or no or false */
1055                        opts->utf8 = 0;
1056                        break;
1057                case Opt_utf8_yes:              /* empty or 1 or yes or true */
1058                        opts->utf8 = 1;
1059                        break;
1060                case Opt_uni_xl_no:             /* 0 or no or false */
1061                        opts->unicode_xlate = 0;
1062                        break;
1063                case Opt_uni_xl_yes:            /* empty or 1 or yes or true */
1064                        opts->unicode_xlate = 1;
1065                        break;
1066                case Opt_nonumtail_no:          /* 0 or no or false */
1067                        opts->numtail = 1;      /* negated option */
1068                        break;
1069                case Opt_nonumtail_yes:         /* empty or 1 or yes or true */
1070                        opts->numtail = 0;      /* negated option */
1071                        break;
1072                case Opt_rodir:
1073                        opts->rodir = 1;
1074                        break;
1075                case Opt_discard:
1076                        opts->discard = 1;
1077                        break;
1078                case Opt_nfs:
1079                        opts->nfs = 1;
1080                        break;
1081
1082                /* obsolete mount options */
1083                case Opt_obsolete:
1084                        fat_msg(sb, KERN_INFO, "\"%s\" option is obsolete, "
1085                               "not supported now", p);
1086                        break;
1087                /* unknown option */
1088                default:
1089                        if (!silent) {
1090                                fat_msg(sb, KERN_ERR,
1091                                       "Unrecognized mount option \"%s\" "
1092                                       "or missing value", p);
1093                        }
1094                        return -EINVAL;
1095                }
1096        }
1097
1098out:
1099        /* UTF-8 doesn't provide FAT semantics */
1100        if (!strcmp(opts->iocharset, "utf8")) {
1101                fat_msg(sb, KERN_WARNING, "utf8 is not a recommended IO charset"
1102                       " for FAT filesystems, filesystem will be "
1103                       "case sensitive!");
1104        }
1105
1106        /* If user doesn't specify allow_utime, it's initialized from dmask. */
1107        if (opts->allow_utime == (unsigned short)-1)
1108                opts->allow_utime = ~opts->fs_dmask & (S_IWGRP | S_IWOTH);
1109        if (opts->unicode_xlate)
1110                opts->utf8 = 0;
1111
1112        return 0;
1113}
1114
1115static int fat_read_root(struct inode *inode)
1116{
1117        struct super_block *sb = inode->i_sb;
1118        struct msdos_sb_info *sbi = MSDOS_SB(sb);
1119        int error;
1120
1121        MSDOS_I(inode)->i_pos = 0;
1122        inode->i_uid = sbi->options.fs_uid;
1123        inode->i_gid = sbi->options.fs_gid;
1124        inode->i_version++;
1125        inode->i_generation = 0;
1126        inode->i_mode = fat_make_mode(sbi, ATTR_DIR, S_IRWXUGO);
1127        inode->i_op = sbi->dir_ops;
1128        inode->i_fop = &fat_dir_operations;
1129        if (sbi->fat_bits == 32) {
1130                MSDOS_I(inode)->i_start = sbi->root_cluster;
1131                error = fat_calc_dir_size(inode);
1132                if (error < 0)
1133                        return error;
1134        } else {
1135                MSDOS_I(inode)->i_start = 0;
1136                inode->i_size = sbi->dir_entries * sizeof(struct msdos_dir_entry);
1137        }
1138        inode->i_blocks = ((inode->i_size + (sbi->cluster_size - 1))
1139                           & ~((loff_t)sbi->cluster_size - 1)) >> 9;
1140        MSDOS_I(inode)->i_logstart = 0;
1141        MSDOS_I(inode)->mmu_private = inode->i_size;
1142
1143        fat_save_attrs(inode, ATTR_DIR);
1144        inode->i_mtime.tv_sec = inode->i_atime.tv_sec = inode->i_ctime.tv_sec = 0;
1145        inode->i_mtime.tv_nsec = inode->i_atime.tv_nsec = inode->i_ctime.tv_nsec = 0;
1146        set_nlink(inode, fat_subdirs(inode)+2);
1147
1148        return 0;
1149}
1150
1151/*
1152 * Read the super block of an MS-DOS FS.
1153 */
1154int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat,
1155                   void (*setup)(struct super_block *))
1156{
1157        struct inode *root_inode = NULL, *fat_inode = NULL;
1158        struct inode *fsinfo_inode = NULL;
1159        struct buffer_head *bh;
1160        struct fat_boot_sector *b;
1161        struct msdos_sb_info *sbi;
1162        u16 logical_sector_size;
1163        u32 total_sectors, total_clusters, fat_clusters, rootdir_sectors;
1164        int debug;
1165        unsigned int media;
1166        long error;
1167        char buf[50];
1168
1169        /*
1170         * GFP_KERNEL is ok here, because while we do hold the
1171         * supeblock lock, memory pressure can't call back into
1172         * the filesystem, since we're only just about to mount
1173         * it and have no inodes etc active!
1174         */
1175        sbi = kzalloc(sizeof(struct msdos_sb_info), GFP_KERNEL);
1176        if (!sbi)
1177                return -ENOMEM;
1178        sb->s_fs_info = sbi;
1179
1180        sb->s_flags |= MS_NODIRATIME;
1181        sb->s_magic = MSDOS_SUPER_MAGIC;
1182        sb->s_op = &fat_sops;
1183        sb->s_export_op = &fat_export_ops;
1184        ratelimit_state_init(&sbi->ratelimit, DEFAULT_RATELIMIT_INTERVAL,
1185                             DEFAULT_RATELIMIT_BURST);
1186
1187        error = parse_options(sb, data, isvfat, silent, &debug, &sbi->options);
1188        if (error)
1189                goto out_fail;
1190
1191        setup(sb); /* flavour-specific stuff that needs options */
1192
1193        error = -EIO;
1194        sb_min_blocksize(sb, 512);
1195        bh = sb_bread(sb, 0);
1196        if (bh == NULL) {
1197                fat_msg(sb, KERN_ERR, "unable to read boot sector");
1198                goto out_fail;
1199        }
1200
1201        b = (struct fat_boot_sector *) bh->b_data;
1202        if (!b->reserved) {
1203                if (!silent)
1204                        fat_msg(sb, KERN_ERR, "bogus number of reserved sectors");
1205                brelse(bh);
1206                goto out_invalid;
1207        }
1208        if (!b->fats) {
1209                if (!silent)
1210                        fat_msg(sb, KERN_ERR, "bogus number of FAT structure");
1211                brelse(bh);
1212                goto out_invalid;
1213        }
1214
1215        /*
1216         * Earlier we checked here that b->secs_track and b->head are nonzero,
1217         * but it turns out valid FAT filesystems can have zero there.
1218         */
1219
1220        media = b->media;
1221        if (!fat_valid_media(media)) {
1222                if (!silent)
1223                        fat_msg(sb, KERN_ERR, "invalid media value (0x%02x)",
1224                               media);
1225                brelse(bh);
1226                goto out_invalid;
1227        }
1228        logical_sector_size = get_unaligned_le16(&b->sector_size);
1229        if (!is_power_of_2(logical_sector_size)
1230            || (logical_sector_size < 512)
1231            || (logical_sector_size > 4096)) {
1232                if (!silent)
1233                        fat_msg(sb, KERN_ERR, "bogus logical sector size %u",
1234                               logical_sector_size);
1235                brelse(bh);
1236                goto out_invalid;
1237        }
1238        sbi->sec_per_clus = b->sec_per_clus;
1239        if (!is_power_of_2(sbi->sec_per_clus)) {
1240                if (!silent)
1241                        fat_msg(sb, KERN_ERR, "bogus sectors per cluster %u",
1242                               sbi->sec_per_clus);
1243                brelse(bh);
1244                goto out_invalid;
1245        }
1246
1247        if (logical_sector_size < sb->s_blocksize) {
1248                fat_msg(sb, KERN_ERR, "logical sector size too small for device"
1249                       " (logical sector size = %u)", logical_sector_size);
1250                brelse(bh);
1251                goto out_fail;
1252        }
1253        if (logical_sector_size > sb->s_blocksize) {
1254                brelse(bh);
1255
1256                if (!sb_set_blocksize(sb, logical_sector_size)) {
1257                        fat_msg(sb, KERN_ERR, "unable to set blocksize %u",
1258                               logical_sector_size);
1259                        goto out_fail;
1260                }
1261                bh = sb_bread(sb, 0);
1262                if (bh == NULL) {
1263                        fat_msg(sb, KERN_ERR, "unable to read boot sector"
1264                               " (logical sector size = %lu)",
1265                               sb->s_blocksize);
1266                        goto out_fail;
1267                }
1268                b = (struct fat_boot_sector *) bh->b_data;
1269        }
1270
1271        mutex_init(&sbi->s_lock);
1272        sbi->cluster_size = sb->s_blocksize * sbi->sec_per_clus;
1273        sbi->cluster_bits = ffs(sbi->cluster_size) - 1;
1274        sbi->fats = b->fats;
1275        sbi->fat_bits = 0;              /* Don't know yet */
1276        sbi->fat_start = le16_to_cpu(b->reserved);
1277        sbi->fat_length = le16_to_cpu(b->fat_length);
1278        sbi->root_cluster = 0;
1279        sbi->free_clusters = -1;        /* Don't know yet */
1280        sbi->free_clus_valid = 0;
1281        sbi->prev_free = FAT_START_ENT;
1282        sb->s_maxbytes = 0xffffffff;
1283
1284        if (!sbi->fat_length && b->fat32_length) {
1285                struct fat_boot_fsinfo *fsinfo;
1286                struct buffer_head *fsinfo_bh;
1287
1288                /* Must be FAT32 */
1289                sbi->fat_bits = 32;
1290                sbi->fat_length = le32_to_cpu(b->fat32_length);
1291                sbi->root_cluster = le32_to_cpu(b->root_cluster);
1292
1293                /* MC - if info_sector is 0, don't multiply by 0 */
1294                sbi->fsinfo_sector = le16_to_cpu(b->info_sector);
1295                if (sbi->fsinfo_sector == 0)
1296                        sbi->fsinfo_sector = 1;
1297
1298                fsinfo_bh = sb_bread(sb, sbi->fsinfo_sector);
1299                if (fsinfo_bh == NULL) {
1300                        fat_msg(sb, KERN_ERR, "bread failed, FSINFO block"
1301                               " (sector = %lu)", sbi->fsinfo_sector);
1302                        brelse(bh);
1303                        goto out_fail;
1304                }
1305
1306                fsinfo = (struct fat_boot_fsinfo *)fsinfo_bh->b_data;
1307                if (!IS_FSINFO(fsinfo)) {
1308                        fat_msg(sb, KERN_WARNING, "Invalid FSINFO signature: "
1309                               "0x%08x, 0x%08x (sector = %lu)",
1310                               le32_to_cpu(fsinfo->signature1),
1311                               le32_to_cpu(fsinfo->signature2),
1312                               sbi->fsinfo_sector);
1313                } else {
1314                        if (sbi->options.usefree)
1315                                sbi->free_clus_valid = 1;
1316                        sbi->free_clusters = le32_to_cpu(fsinfo->free_clusters);
1317                        sbi->prev_free = le32_to_cpu(fsinfo->next_cluster);
1318                }
1319
1320                brelse(fsinfo_bh);
1321        }
1322
1323        sbi->dir_per_block = sb->s_blocksize / sizeof(struct msdos_dir_entry);
1324        sbi->dir_per_block_bits = ffs(sbi->dir_per_block) - 1;
1325
1326        sbi->dir_start = sbi->fat_start + sbi->fats * sbi->fat_length;
1327        sbi->dir_entries = get_unaligned_le16(&b->dir_entries);
1328        if (sbi->dir_entries & (sbi->dir_per_block - 1)) {
1329                if (!silent)
1330                        fat_msg(sb, KERN_ERR, "bogus directroy-entries per block"
1331                               " (%u)", sbi->dir_entries);
1332                brelse(bh);
1333                goto out_invalid;
1334        }
1335
1336        rootdir_sectors = sbi->dir_entries
1337                * sizeof(struct msdos_dir_entry) / sb->s_blocksize;
1338        sbi->data_start = sbi->dir_start + rootdir_sectors;
1339        total_sectors = get_unaligned_le16(&b->sectors);
1340        if (total_sectors == 0)
1341                total_sectors = le32_to_cpu(b->total_sect);
1342
1343        total_clusters = (total_sectors - sbi->data_start) / sbi->sec_per_clus;
1344
1345        if (sbi->fat_bits != 32)
1346                sbi->fat_bits = (total_clusters > MAX_FAT12) ? 16 : 12;
1347
1348        /* check that FAT table does not overflow */
1349        fat_clusters = sbi->fat_length * sb->s_blocksize * 8 / sbi->fat_bits;
1350        total_clusters = min(total_clusters, fat_clusters - FAT_START_ENT);
1351        if (total_clusters > MAX_FAT(sb)) {
1352                if (!silent)
1353                        fat_msg(sb, KERN_ERR, "count of clusters too big (%u)",
1354                               total_clusters);
1355                brelse(bh);
1356                goto out_invalid;
1357        }
1358
1359        sbi->max_cluster = total_clusters + FAT_START_ENT;
1360        /* check the free_clusters, it's not necessarily correct */
1361        if (sbi->free_clusters != -1 && sbi->free_clusters > total_clusters)
1362                sbi->free_clusters = -1;
1363        /* check the prev_free, it's not necessarily correct */
1364        sbi->prev_free %= sbi->max_cluster;
1365        if (sbi->prev_free < FAT_START_ENT)
1366                sbi->prev_free = FAT_START_ENT;
1367
1368        brelse(bh);
1369
1370        /* set up enough so that it can read an inode */
1371        fat_hash_init(sb);
1372        dir_hash_init(sb);
1373        fat_ent_access_init(sb);
1374
1375        /*
1376         * The low byte of FAT's first entry must have same value with
1377         * media-field.  But in real world, too many devices is
1378         * writing wrong value.  So, removed that validity check.
1379         *
1380         * if (FAT_FIRST_ENT(sb, media) != first)
1381         */
1382
1383        error = -EINVAL;
1384        sprintf(buf, "cp%d", sbi->options.codepage);
1385        sbi->nls_disk = load_nls(buf);
1386        if (!sbi->nls_disk) {
1387                fat_msg(sb, KERN_ERR, "codepage %s not found", buf);
1388                goto out_fail;
1389        }
1390
1391        /* FIXME: utf8 is using iocharset for upper/lower conversion */
1392        if (sbi->options.isvfat) {
1393                sbi->nls_io = load_nls(sbi->options.iocharset);
1394                if (!sbi->nls_io) {
1395                        fat_msg(sb, KERN_ERR, "IO charset %s not found",
1396                               sbi->options.iocharset);
1397                        goto out_fail;
1398                }
1399        }
1400
1401        error = -ENOMEM;
1402        fat_inode = new_inode(sb);
1403        if (!fat_inode)
1404                goto out_fail;
1405        MSDOS_I(fat_inode)->i_pos = 0;
1406        sbi->fat_inode = fat_inode;
1407
1408        fsinfo_inode = new_inode(sb);
1409        if (!fsinfo_inode)
1410                goto out_fail;
1411        fsinfo_inode->i_ino = MSDOS_FSINFO_INO;
1412        sbi->fsinfo_inode = fsinfo_inode;
1413        insert_inode_hash(fsinfo_inode);
1414
1415        root_inode = new_inode(sb);
1416        if (!root_inode)
1417                goto out_fail;
1418        root_inode->i_ino = MSDOS_ROOT_INO;
1419        root_inode->i_version = 1;
1420        error = fat_read_root(root_inode);
1421        if (error < 0) {
1422                iput(root_inode);
1423                goto out_fail;
1424        }
1425        error = -ENOMEM;
1426        insert_inode_hash(root_inode);
1427        fat_attach(root_inode, 0);
1428        sb->s_root = d_make_root(root_inode);
1429        if (!sb->s_root) {
1430                fat_msg(sb, KERN_ERR, "get root inode failed");
1431                goto out_fail;
1432        }
1433
1434        return 0;
1435
1436out_invalid:
1437        error = -EINVAL;
1438        if (!silent)
1439                fat_msg(sb, KERN_INFO, "Can't find a valid FAT filesystem");
1440
1441out_fail:
1442        if (fsinfo_inode)
1443                iput(fsinfo_inode);
1444        if (fat_inode)
1445                iput(fat_inode);
1446        unload_nls(sbi->nls_io);
1447        unload_nls(sbi->nls_disk);
1448        if (sbi->options.iocharset != fat_default_iocharset)
1449                kfree(sbi->options.iocharset);
1450        sb->s_fs_info = NULL;
1451        kfree(sbi);
1452        return error;
1453}
1454
1455EXPORT_SYMBOL_GPL(fat_fill_super);
1456
1457/*
1458 * helper function for fat_flush_inodes.  This writes both the inode
1459 * and the file data blocks, waiting for in flight data blocks before
1460 * the start of the call.  It does not wait for any io started
1461 * during the call
1462 */
1463static int writeback_inode(struct inode *inode)
1464{
1465
1466        int ret;
1467
1468        /* if we used wait=1, sync_inode_metadata waits for the io for the
1469        * inode to finish.  So wait=0 is sent down to sync_inode_metadata
1470        * and filemap_fdatawrite is used for the data blocks
1471        */
1472        ret = sync_inode_metadata(inode, 0);
1473        if (!ret)
1474                ret = filemap_fdatawrite(inode->i_mapping);
1475        return ret;
1476}
1477
1478/*
1479 * write data and metadata corresponding to i1 and i2.  The io is
1480 * started but we do not wait for any of it to finish.
1481 *
1482 * filemap_flush is used for the block device, so if there is a dirty
1483 * page for a block already in flight, we will not wait and start the
1484 * io over again
1485 */
1486int fat_flush_inodes(struct super_block *sb, struct inode *i1, struct inode *i2)
1487{
1488        int ret = 0;
1489        if (!MSDOS_SB(sb)->options.flush)
1490                return 0;
1491        if (i1)
1492                ret = writeback_inode(i1);
1493        if (!ret && i2)
1494                ret = writeback_inode(i2);
1495        if (!ret) {
1496                struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping;
1497                ret = filemap_flush(mapping);
1498        }
1499        return ret;
1500}
1501EXPORT_SYMBOL_GPL(fat_flush_inodes);
1502
1503static int __init init_fat_fs(void)
1504{
1505        int err;
1506
1507        err = fat_cache_init();
1508        if (err)
1509                return err;
1510
1511        err = fat_init_inodecache();
1512        if (err)
1513                goto failed;
1514
1515        return 0;
1516
1517failed:
1518        fat_cache_destroy();
1519        return err;
1520}
1521
1522static void __exit exit_fat_fs(void)
1523{
1524        fat_cache_destroy();
1525        fat_destroy_inodecache();
1526}
1527
1528module_init(init_fat_fs)
1529module_exit(exit_fat_fs)
1530
1531MODULE_LICENSE("GPL");
1532
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