1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 *  linux/fs/fat/inode.c
   4 *
   5 *  Written 1992,1993 by Werner Almesberger
   6 *  VFAT extensions by Gordon Chaffee, merged with msdos fs by Henrik Storner
   7 *  Rewritten for the constant inumbers support by Al Viro
   8 *
   9 *  Fixes:
  10 *
  11 *	Max Cohan: Fixed invalid FSINFO offset when info_sector is 0
  12 */
  13
  14#include <linux/module.h>
 
 
 
 
  15#include <linux/pagemap.h>
  16#include <linux/mpage.h>
 
 
 
  17#include <linux/vfs.h>
  18#include <linux/seq_file.h>
  19#include <linux/parser.h>
  20#include <linux/uio.h>
  21#include <linux/blkdev.h>
  22#include <linux/backing-dev.h>
 
  23#include <asm/unaligned.h>
  24#include <linux/random.h>
  25#include <linux/iversion.h>
  26#include "fat.h"
  27
  28#ifndef CONFIG_FAT_DEFAULT_IOCHARSET
  29/* if user don't select VFAT, this is undefined. */
  30#define CONFIG_FAT_DEFAULT_IOCHARSET	""
  31#endif
  32
  33#define KB_IN_SECTORS 2
  34
  35/* DOS dates from 1980/1/1 through 2107/12/31 */
  36#define FAT_DATE_MIN (0<<9 | 1<<5 | 1)
  37#define FAT_DATE_MAX (127<<9 | 12<<5 | 31)
  38#define FAT_TIME_MAX (23<<11 | 59<<5 | 29)
  39
  40/*
  41 * A deserialized copy of the on-disk structure laid out in struct
  42 * fat_boot_sector.
  43 */
  44struct fat_bios_param_block {
  45	u16	fat_sector_size;
  46	u8	fat_sec_per_clus;
  47	u16	fat_reserved;
  48	u8	fat_fats;
  49	u16	fat_dir_entries;
  50	u16	fat_sectors;
  51	u16	fat_fat_length;
  52	u32	fat_total_sect;
  53
  54	u8	fat16_state;
  55	u32	fat16_vol_id;
  56
  57	u32	fat32_length;
  58	u32	fat32_root_cluster;
  59	u16	fat32_info_sector;
  60	u8	fat32_state;
  61	u32	fat32_vol_id;
  62};
  63
  64static int fat_default_codepage = CONFIG_FAT_DEFAULT_CODEPAGE;
  65static char fat_default_iocharset[] = CONFIG_FAT_DEFAULT_IOCHARSET;
  66
  67static struct fat_floppy_defaults {
  68	unsigned nr_sectors;
  69	unsigned sec_per_clus;
  70	unsigned dir_entries;
  71	unsigned media;
  72	unsigned fat_length;
  73} floppy_defaults[] = {
  74{
  75	.nr_sectors = 160 * KB_IN_SECTORS,
  76	.sec_per_clus = 1,
  77	.dir_entries = 64,
  78	.media = 0xFE,
  79	.fat_length = 1,
  80},
  81{
  82	.nr_sectors = 180 * KB_IN_SECTORS,
  83	.sec_per_clus = 1,
  84	.dir_entries = 64,
  85	.media = 0xFC,
  86	.fat_length = 2,
  87},
  88{
  89	.nr_sectors = 320 * KB_IN_SECTORS,
  90	.sec_per_clus = 2,
  91	.dir_entries = 112,
  92	.media = 0xFF,
  93	.fat_length = 1,
  94},
  95{
  96	.nr_sectors = 360 * KB_IN_SECTORS,
  97	.sec_per_clus = 2,
  98	.dir_entries = 112,
  99	.media = 0xFD,
 100	.fat_length = 2,
 101},
 102};
 103
 104int fat_add_cluster(struct inode *inode)
 105{
 106	int err, cluster;
 107
 108	err = fat_alloc_clusters(inode, &cluster, 1);
 109	if (err)
 110		return err;
 111	/* FIXME: this cluster should be added after data of this
 112	 * cluster is writed */
 113	err = fat_chain_add(inode, cluster, 1);
 114	if (err)
 115		fat_free_clusters(inode, cluster);
 116	return err;
 117}
 118
 119static inline int __fat_get_block(struct inode *inode, sector_t iblock,
 120				  unsigned long *max_blocks,
 121				  struct buffer_head *bh_result, int create)
 122{
 123	struct super_block *sb = inode->i_sb;
 124	struct msdos_sb_info *sbi = MSDOS_SB(sb);
 125	unsigned long mapped_blocks;
 126	sector_t phys, last_block;
 127	int err, offset;
 128
 129	err = fat_bmap(inode, iblock, &phys, &mapped_blocks, create, false);
 130	if (err)
 131		return err;
 132	if (phys) {
 133		map_bh(bh_result, sb, phys);
 134		*max_blocks = min(mapped_blocks, *max_blocks);
 135		return 0;
 136	}
 137	if (!create)
 138		return 0;
 139
 140	if (iblock != MSDOS_I(inode)->mmu_private >> sb->s_blocksize_bits) {
 141		fat_fs_error(sb, "corrupted file size (i_pos %lld, %lld)",
 142			MSDOS_I(inode)->i_pos, MSDOS_I(inode)->mmu_private);
 143		return -EIO;
 144	}
 145
 146	last_block = inode->i_blocks >> (sb->s_blocksize_bits - 9);
 147	offset = (unsigned long)iblock & (sbi->sec_per_clus - 1);
 148	/*
 149	 * allocate a cluster according to the following.
 150	 * 1) no more available blocks
 151	 * 2) not part of fallocate region
 152	 */
 153	if (!offset && !(iblock < last_block)) {
 154		/* TODO: multiple cluster allocation would be desirable. */
 155		err = fat_add_cluster(inode);
 156		if (err)
 157			return err;
 158	}
 159	/* available blocks on this cluster */
 160	mapped_blocks = sbi->sec_per_clus - offset;
 161
 162	*max_blocks = min(mapped_blocks, *max_blocks);
 163	MSDOS_I(inode)->mmu_private += *max_blocks << sb->s_blocksize_bits;
 164
 165	err = fat_bmap(inode, iblock, &phys, &mapped_blocks, create, false);
 166	if (err)
 167		return err;
 168	if (!phys) {
 169		fat_fs_error(sb,
 170			     "invalid FAT chain (i_pos %lld, last_block %llu)",
 171			     MSDOS_I(inode)->i_pos,
 172			     (unsigned long long)last_block);
 173		return -EIO;
 174	}
 175
 
 176	BUG_ON(*max_blocks != mapped_blocks);
 177	set_buffer_new(bh_result);
 178	map_bh(bh_result, sb, phys);
 179
 180	return 0;
 181}
 182
 183static int fat_get_block(struct inode *inode, sector_t iblock,
 184			 struct buffer_head *bh_result, int create)
 185{
 186	struct super_block *sb = inode->i_sb;
 187	unsigned long max_blocks = bh_result->b_size >> inode->i_blkbits;
 188	int err;
 189
 190	err = __fat_get_block(inode, iblock, &max_blocks, bh_result, create);
 191	if (err)
 192		return err;
 193	bh_result->b_size = max_blocks << sb->s_blocksize_bits;
 194	return 0;
 195}
 196
 197static int fat_writepage(struct page *page, struct writeback_control *wbc)
 198{
 199	return block_write_full_page(page, fat_get_block, wbc);
 200}
 201
 202static int fat_writepages(struct address_space *mapping,
 203			  struct writeback_control *wbc)
 204{
 205	return mpage_writepages(mapping, wbc, fat_get_block);
 206}
 207
 208static int fat_readpage(struct file *file, struct page *page)
 209{
 210	return mpage_readpage(page, fat_get_block);
 211}
 212
 213static void fat_readahead(struct readahead_control *rac)
 
 214{
 215	mpage_readahead(rac, fat_get_block);
 216}
 217
 218static void fat_write_failed(struct address_space *mapping, loff_t to)
 219{
 220	struct inode *inode = mapping->host;
 221
 222	if (to > inode->i_size) {
 223		truncate_pagecache(inode, inode->i_size);
 224		fat_truncate_blocks(inode, inode->i_size);
 225	}
 226}
 227
 228static int fat_write_begin(struct file *file, struct address_space *mapping,
 229			loff_t pos, unsigned len, unsigned flags,
 230			struct page **pagep, void **fsdata)
 231{
 232	int err;
 233
 234	*pagep = NULL;
 235	err = cont_write_begin(file, mapping, pos, len, flags,
 236				pagep, fsdata, fat_get_block,
 237				&MSDOS_I(mapping->host)->mmu_private);
 238	if (err < 0)
 239		fat_write_failed(mapping, pos + len);
 240	return err;
 241}
 242
 243static int fat_write_end(struct file *file, struct address_space *mapping,
 244			loff_t pos, unsigned len, unsigned copied,
 245			struct page *pagep, void *fsdata)
 246{
 247	struct inode *inode = mapping->host;
 248	int err;
 249	err = generic_write_end(file, mapping, pos, len, copied, pagep, fsdata);
 250	if (err < len)
 251		fat_write_failed(mapping, pos + len);
 252	if (!(err < 0) && !(MSDOS_I(inode)->i_attrs & ATTR_ARCH)) {
 253		fat_truncate_time(inode, NULL, S_CTIME|S_MTIME);
 254		MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
 255		mark_inode_dirty(inode);
 256	}
 257	return err;
 258}
 259
 260static ssize_t fat_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
 
 
 261{
 262	struct file *file = iocb->ki_filp;
 263	struct address_space *mapping = file->f_mapping;
 264	struct inode *inode = mapping->host;
 265	size_t count = iov_iter_count(iter);
 266	loff_t offset = iocb->ki_pos;
 267	ssize_t ret;
 268
 269	if (iov_iter_rw(iter) == WRITE) {
 270		/*
 271		 * FIXME: blockdev_direct_IO() doesn't use ->write_begin(),
 272		 * so we need to update the ->mmu_private to block boundary.
 273		 *
 274		 * But we must fill the remaining area or hole by nul for
 275		 * updating ->mmu_private.
 276		 *
 277		 * Return 0, and fallback to normal buffered write.
 278		 */
 279		loff_t size = offset + count;
 280		if (MSDOS_I(inode)->mmu_private < size)
 281			return 0;
 282	}
 283
 284	/*
 285	 * FAT need to use the DIO_LOCKING for avoiding the race
 286	 * condition of fat_get_block() and ->truncate().
 287	 */
 288	ret = blockdev_direct_IO(iocb, inode, iter, fat_get_block);
 289	if (ret < 0 && iov_iter_rw(iter) == WRITE)
 290		fat_write_failed(mapping, offset + count);
 
 291
 292	return ret;
 293}
 294
 295static int fat_get_block_bmap(struct inode *inode, sector_t iblock,
 296		struct buffer_head *bh_result, int create)
 297{
 298	struct super_block *sb = inode->i_sb;
 299	unsigned long max_blocks = bh_result->b_size >> inode->i_blkbits;
 300	int err;
 301	sector_t bmap;
 302	unsigned long mapped_blocks;
 303
 304	BUG_ON(create != 0);
 305
 306	err = fat_bmap(inode, iblock, &bmap, &mapped_blocks, create, true);
 307	if (err)
 308		return err;
 309
 310	if (bmap) {
 311		map_bh(bh_result, sb, bmap);
 312		max_blocks = min(mapped_blocks, max_blocks);
 313	}
 314
 315	bh_result->b_size = max_blocks << sb->s_blocksize_bits;
 316
 317	return 0;
 318}
 319
 320static sector_t _fat_bmap(struct address_space *mapping, sector_t block)
 321{
 322	sector_t blocknr;
 323
 324	/* fat_get_cluster() assumes the requested blocknr isn't truncated. */
 325	down_read(&MSDOS_I(mapping->host)->truncate_lock);
 326	blocknr = generic_block_bmap(mapping, block, fat_get_block_bmap);
 327	up_read(&MSDOS_I(mapping->host)->truncate_lock);
 328
 329	return blocknr;
 330}
 331
 332/*
 333 * fat_block_truncate_page() zeroes out a mapping from file offset `from'
 334 * up to the end of the block which corresponds to `from'.
 335 * This is required during truncate to physically zeroout the tail end
 336 * of that block so it doesn't yield old data if the file is later grown.
 337 * Also, avoid causing failure from fsx for cases of "data past EOF"
 338 */
 339int fat_block_truncate_page(struct inode *inode, loff_t from)
 340{
 341	return block_truncate_page(inode->i_mapping, from, fat_get_block);
 342}
 343
 344static const struct address_space_operations fat_aops = {
 345	.set_page_dirty	= __set_page_dirty_buffers,
 346	.readpage	= fat_readpage,
 347	.readahead	= fat_readahead,
 348	.writepage	= fat_writepage,
 349	.writepages	= fat_writepages,
 350	.write_begin	= fat_write_begin,
 351	.write_end	= fat_write_end,
 352	.direct_IO	= fat_direct_IO,
 353	.bmap		= _fat_bmap
 354};
 355
 356/*
 357 * New FAT inode stuff. We do the following:
 358 *	a) i_ino is constant and has nothing with on-disk location.
 359 *	b) FAT manages its own cache of directory entries.
 360 *	c) *This* cache is indexed by on-disk location.
 361 *	d) inode has an associated directory entry, all right, but
 362 *		it may be unhashed.
 363 *	e) currently entries are stored within struct inode. That should
 364 *		change.
 365 *	f) we deal with races in the following way:
 366 *		1. readdir() and lookup() do FAT-dir-cache lookup.
 367 *		2. rename() unhashes the F-d-c entry and rehashes it in
 368 *			a new place.
 369 *		3. unlink() and rmdir() unhash F-d-c entry.
 370 *		4. fat_write_inode() checks whether the thing is unhashed.
 371 *			If it is we silently return. If it isn't we do bread(),
 372 *			check if the location is still valid and retry if it
 373 *			isn't. Otherwise we do changes.
 374 *		5. Spinlock is used to protect hash/unhash/location check/lookup
 375 *		6. fat_evict_inode() unhashes the F-d-c entry.
 376 *		7. lookup() and readdir() do igrab() if they find a F-d-c entry
 377 *			and consider negative result as cache miss.
 378 */
 379
 380static void fat_hash_init(struct super_block *sb)
 381{
 382	struct msdos_sb_info *sbi = MSDOS_SB(sb);
 383	int i;
 384
 385	spin_lock_init(&sbi->inode_hash_lock);
 386	for (i = 0; i < FAT_HASH_SIZE; i++)
 387		INIT_HLIST_HEAD(&sbi->inode_hashtable[i]);
 388}
 389
 390static inline unsigned long fat_hash(loff_t i_pos)
 391{
 392	return hash_32(i_pos, FAT_HASH_BITS);
 393}
 394
 395static void dir_hash_init(struct super_block *sb)
 396{
 397	struct msdos_sb_info *sbi = MSDOS_SB(sb);
 398	int i;
 399
 400	spin_lock_init(&sbi->dir_hash_lock);
 401	for (i = 0; i < FAT_HASH_SIZE; i++)
 402		INIT_HLIST_HEAD(&sbi->dir_hashtable[i]);
 403}
 404
 405void fat_attach(struct inode *inode, loff_t i_pos)
 406{
 407	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 
 408
 409	if (inode->i_ino != MSDOS_ROOT_INO) {
 410		struct hlist_head *head =   sbi->inode_hashtable
 411					  + fat_hash(i_pos);
 412
 413		spin_lock(&sbi->inode_hash_lock);
 414		MSDOS_I(inode)->i_pos = i_pos;
 415		hlist_add_head(&MSDOS_I(inode)->i_fat_hash, head);
 416		spin_unlock(&sbi->inode_hash_lock);
 417	}
 418
 419	/* If NFS support is enabled, cache the mapping of start cluster
 420	 * to directory inode. This is used during reconnection of
 421	 * dentries to the filesystem root.
 422	 */
 423	if (S_ISDIR(inode->i_mode) && sbi->options.nfs) {
 424		struct hlist_head *d_head = sbi->dir_hashtable;
 425		d_head += fat_dir_hash(MSDOS_I(inode)->i_logstart);
 426
 427		spin_lock(&sbi->dir_hash_lock);
 428		hlist_add_head(&MSDOS_I(inode)->i_dir_hash, d_head);
 429		spin_unlock(&sbi->dir_hash_lock);
 430	}
 431}
 432EXPORT_SYMBOL_GPL(fat_attach);
 433
 434void fat_detach(struct inode *inode)
 435{
 436	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 437	spin_lock(&sbi->inode_hash_lock);
 438	MSDOS_I(inode)->i_pos = 0;
 439	hlist_del_init(&MSDOS_I(inode)->i_fat_hash);
 440	spin_unlock(&sbi->inode_hash_lock);
 441
 442	if (S_ISDIR(inode->i_mode) && sbi->options.nfs) {
 443		spin_lock(&sbi->dir_hash_lock);
 444		hlist_del_init(&MSDOS_I(inode)->i_dir_hash);
 445		spin_unlock(&sbi->dir_hash_lock);
 446	}
 447}
 448EXPORT_SYMBOL_GPL(fat_detach);
 449
 450struct inode *fat_iget(struct super_block *sb, loff_t i_pos)
 451{
 452	struct msdos_sb_info *sbi = MSDOS_SB(sb);
 453	struct hlist_head *head = sbi->inode_hashtable + fat_hash(i_pos);
 
 454	struct msdos_inode_info *i;
 455	struct inode *inode = NULL;
 456
 457	spin_lock(&sbi->inode_hash_lock);
 458	hlist_for_each_entry(i, head, i_fat_hash) {
 459		BUG_ON(i->vfs_inode.i_sb != sb);
 460		if (i->i_pos != i_pos)
 461			continue;
 462		inode = igrab(&i->vfs_inode);
 463		if (inode)
 464			break;
 465	}
 466	spin_unlock(&sbi->inode_hash_lock);
 467	return inode;
 468}
 469
 470static int is_exec(unsigned char *extension)
 471{
 472	unsigned char exe_extensions[] = "EXECOMBAT", *walk;
 473
 474	for (walk = exe_extensions; *walk; walk += 3)
 475		if (!strncmp(extension, walk, 3))
 476			return 1;
 477	return 0;
 478}
 479
 480static int fat_calc_dir_size(struct inode *inode)
 481{
 482	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 483	int ret, fclus, dclus;
 484
 485	inode->i_size = 0;
 486	if (MSDOS_I(inode)->i_start == 0)
 487		return 0;
 488
 489	ret = fat_get_cluster(inode, FAT_ENT_EOF, &fclus, &dclus);
 490	if (ret < 0)
 491		return ret;
 492	inode->i_size = (fclus + 1) << sbi->cluster_bits;
 493
 494	return 0;
 495}
 496
 497static int fat_validate_dir(struct inode *dir)
 498{
 499	struct super_block *sb = dir->i_sb;
 500
 501	if (dir->i_nlink < 2) {
 502		/* Directory should have "."/".." entries at least. */
 503		fat_fs_error(sb, "corrupted directory (invalid entries)");
 504		return -EIO;
 505	}
 506	if (MSDOS_I(dir)->i_start == 0 ||
 507	    MSDOS_I(dir)->i_start == MSDOS_SB(sb)->root_cluster) {
 508		/* Directory should point valid cluster. */
 509		fat_fs_error(sb, "corrupted directory (invalid i_start)");
 510		return -EIO;
 511	}
 512	return 0;
 513}
 514
 515/* doesn't deal with root inode */
 516int fat_fill_inode(struct inode *inode, struct msdos_dir_entry *de)
 517{
 518	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 519	int error;
 520
 521	MSDOS_I(inode)->i_pos = 0;
 522	inode->i_uid = sbi->options.fs_uid;
 523	inode->i_gid = sbi->options.fs_gid;
 524	inode_inc_iversion(inode);
 525	inode->i_generation = prandom_u32();
 526
 527	if ((de->attr & ATTR_DIR) && !IS_FREE(de->name)) {
 528		inode->i_generation &= ~1;
 529		inode->i_mode = fat_make_mode(sbi, de->attr, S_IRWXUGO);
 530		inode->i_op = sbi->dir_ops;
 531		inode->i_fop = &fat_dir_operations;
 532
 533		MSDOS_I(inode)->i_start = fat_get_start(sbi, de);
 
 
 
 534		MSDOS_I(inode)->i_logstart = MSDOS_I(inode)->i_start;
 535		error = fat_calc_dir_size(inode);
 536		if (error < 0)
 537			return error;
 538		MSDOS_I(inode)->mmu_private = inode->i_size;
 539
 540		set_nlink(inode, fat_subdirs(inode));
 541
 542		error = fat_validate_dir(inode);
 543		if (error < 0)
 544			return error;
 545	} else { /* not a directory */
 546		inode->i_generation |= 1;
 547		inode->i_mode = fat_make_mode(sbi, de->attr,
 548			((sbi->options.showexec && !is_exec(de->name + 8))
 549			 ? S_IRUGO|S_IWUGO : S_IRWXUGO));
 550		MSDOS_I(inode)->i_start = fat_get_start(sbi, de);
 
 
 551
 552		MSDOS_I(inode)->i_logstart = MSDOS_I(inode)->i_start;
 553		inode->i_size = le32_to_cpu(de->size);
 554		inode->i_op = &fat_file_inode_operations;
 555		inode->i_fop = &fat_file_operations;
 556		inode->i_mapping->a_ops = &fat_aops;
 557		MSDOS_I(inode)->mmu_private = inode->i_size;
 558	}
 559	if (de->attr & ATTR_SYS) {
 560		if (sbi->options.sys_immutable)
 561			inode->i_flags |= S_IMMUTABLE;
 562	}
 563	fat_save_attrs(inode, de->attr);
 564
 565	inode->i_blocks = ((inode->i_size + (sbi->cluster_size - 1))
 566			   & ~((loff_t)sbi->cluster_size - 1)) >> 9;
 567
 568	fat_time_fat2unix(sbi, &inode->i_mtime, de->time, de->date, 0);
 569	if (sbi->options.isvfat) {
 570		fat_time_fat2unix(sbi, &inode->i_ctime, de->ctime,
 571				  de->cdate, de->ctime_cs);
 572		fat_time_fat2unix(sbi, &inode->i_atime, 0, de->adate, 0);
 573	} else
 574		fat_truncate_time(inode, &inode->i_mtime, S_ATIME|S_CTIME);
 575
 576	return 0;
 577}
 578
 579static inline void fat_lock_build_inode(struct msdos_sb_info *sbi)
 580{
 581	if (sbi->options.nfs == FAT_NFS_NOSTALE_RO)
 582		mutex_lock(&sbi->nfs_build_inode_lock);
 583}
 584
 585static inline void fat_unlock_build_inode(struct msdos_sb_info *sbi)
 586{
 587	if (sbi->options.nfs == FAT_NFS_NOSTALE_RO)
 588		mutex_unlock(&sbi->nfs_build_inode_lock);
 589}
 590
 591struct inode *fat_build_inode(struct super_block *sb,
 592			struct msdos_dir_entry *de, loff_t i_pos)
 593{
 594	struct inode *inode;
 595	int err;
 596
 597	fat_lock_build_inode(MSDOS_SB(sb));
 598	inode = fat_iget(sb, i_pos);
 599	if (inode)
 600		goto out;
 601	inode = new_inode(sb);
 602	if (!inode) {
 603		inode = ERR_PTR(-ENOMEM);
 604		goto out;
 605	}
 606	inode->i_ino = iunique(sb, MSDOS_ROOT_INO);
 607	inode_set_iversion(inode, 1);
 608	err = fat_fill_inode(inode, de);
 609	if (err) {
 610		iput(inode);
 611		inode = ERR_PTR(err);
 612		goto out;
 613	}
 614	fat_attach(inode, i_pos);
 615	insert_inode_hash(inode);
 616out:
 617	fat_unlock_build_inode(MSDOS_SB(sb));
 618	return inode;
 619}
 620
 621EXPORT_SYMBOL_GPL(fat_build_inode);
 622
 623static int __fat_write_inode(struct inode *inode, int wait);
 624
 625static void fat_free_eofblocks(struct inode *inode)
 626{
 627	/* Release unwritten fallocated blocks on inode eviction. */
 628	if ((inode->i_blocks << 9) >
 629			round_up(MSDOS_I(inode)->mmu_private,
 630				MSDOS_SB(inode->i_sb)->cluster_size)) {
 631		int err;
 632
 633		fat_truncate_blocks(inode, MSDOS_I(inode)->mmu_private);
 634		/* Fallocate results in updating the i_start/iogstart
 635		 * for the zero byte file. So, make it return to
 636		 * original state during evict and commit it to avoid
 637		 * any corruption on the next access to the cluster
 638		 * chain for the file.
 639		 */
 640		err = __fat_write_inode(inode, inode_needs_sync(inode));
 641		if (err) {
 642			fat_msg(inode->i_sb, KERN_WARNING, "Failed to "
 643					"update on disk inode for unused "
 644					"fallocated blocks, inode could be "
 645					"corrupted. Please run fsck");
 646		}
 647
 648	}
 649}
 650
 651static void fat_evict_inode(struct inode *inode)
 652{
 653	truncate_inode_pages_final(&inode->i_data);
 654	if (!inode->i_nlink) {
 655		inode->i_size = 0;
 656		fat_truncate_blocks(inode, 0);
 657	} else
 658		fat_free_eofblocks(inode);
 659
 660	invalidate_inode_buffers(inode);
 661	clear_inode(inode);
 662	fat_cache_inval_inode(inode);
 663	fat_detach(inode);
 664}
 665
 666static void fat_set_state(struct super_block *sb,
 667			unsigned int set, unsigned int force)
 668{
 669	struct buffer_head *bh;
 670	struct fat_boot_sector *b;
 671	struct msdos_sb_info *sbi = MSDOS_SB(sb);
 672
 673	/* do not change any thing if mounted read only */
 674	if (sb_rdonly(sb) && !force)
 675		return;
 676
 677	/* do not change state if fs was dirty */
 678	if (sbi->dirty) {
 679		/* warn only on set (mount). */
 680		if (set)
 681			fat_msg(sb, KERN_WARNING, "Volume was not properly "
 682				"unmounted. Some data may be corrupt. "
 683				"Please run fsck.");
 684		return;
 685	}
 686
 687	bh = sb_bread(sb, 0);
 688	if (bh == NULL) {
 689		fat_msg(sb, KERN_ERR, "unable to read boot sector "
 690			"to mark fs as dirty");
 691		return;
 692	}
 693
 694	b = (struct fat_boot_sector *) bh->b_data;
 695
 696	if (is_fat32(sbi)) {
 697		if (set)
 698			b->fat32.state |= FAT_STATE_DIRTY;
 699		else
 700			b->fat32.state &= ~FAT_STATE_DIRTY;
 701	} else /* fat 16 and 12 */ {
 702		if (set)
 703			b->fat16.state |= FAT_STATE_DIRTY;
 704		else
 705			b->fat16.state &= ~FAT_STATE_DIRTY;
 706	}
 707
 708	mark_buffer_dirty(bh);
 709	sync_dirty_buffer(bh);
 710	brelse(bh);
 711}
 712
 713static void fat_reset_iocharset(struct fat_mount_options *opts)
 714{
 715	if (opts->iocharset != fat_default_iocharset) {
 716		/* Note: opts->iocharset can be NULL here */
 717		kfree(opts->iocharset);
 718		opts->iocharset = fat_default_iocharset;
 719	}
 720}
 721
 722static void delayed_free(struct rcu_head *p)
 723{
 724	struct msdos_sb_info *sbi = container_of(p, struct msdos_sb_info, rcu);
 725	unload_nls(sbi->nls_disk);
 726	unload_nls(sbi->nls_io);
 727	fat_reset_iocharset(&sbi->options);
 728	kfree(sbi);
 729}
 730
 731static void fat_put_super(struct super_block *sb)
 732{
 733	struct msdos_sb_info *sbi = MSDOS_SB(sb);
 734
 735	fat_set_state(sb, 0, 0);
 736
 737	iput(sbi->fsinfo_inode);
 738	iput(sbi->fat_inode);
 739
 740	call_rcu(&sbi->rcu, delayed_free);
 
 741}
 742
 743static struct kmem_cache *fat_inode_cachep;
 744
 745static struct inode *fat_alloc_inode(struct super_block *sb)
 746{
 747	struct msdos_inode_info *ei;
 748	ei = kmem_cache_alloc(fat_inode_cachep, GFP_NOFS);
 749	if (!ei)
 750		return NULL;
 751
 752	init_rwsem(&ei->truncate_lock);
 753	/* Zeroing to allow iput() even if partial initialized inode. */
 754	ei->mmu_private = 0;
 755	ei->i_start = 0;
 756	ei->i_logstart = 0;
 757	ei->i_attrs = 0;
 758	ei->i_pos = 0;
 759
 760	return &ei->vfs_inode;
 761}
 762
 763static void fat_free_inode(struct inode *inode)
 764{
 
 765	kmem_cache_free(fat_inode_cachep, MSDOS_I(inode));
 766}
 767
 
 
 
 
 
 768static void init_once(void *foo)
 769{
 770	struct msdos_inode_info *ei = (struct msdos_inode_info *)foo;
 771
 772	spin_lock_init(&ei->cache_lru_lock);
 773	ei->nr_caches = 0;
 774	ei->cache_valid_id = FAT_CACHE_VALID + 1;
 775	INIT_LIST_HEAD(&ei->cache_lru);
 776	INIT_HLIST_NODE(&ei->i_fat_hash);
 777	INIT_HLIST_NODE(&ei->i_dir_hash);
 778	inode_init_once(&ei->vfs_inode);
 779}
 780
 781static int __init fat_init_inodecache(void)
 782{
 783	fat_inode_cachep = kmem_cache_create("fat_inode_cache",
 784					     sizeof(struct msdos_inode_info),
 785					     0, (SLAB_RECLAIM_ACCOUNT|
 786						SLAB_MEM_SPREAD|SLAB_ACCOUNT),
 787					     init_once);
 788	if (fat_inode_cachep == NULL)
 789		return -ENOMEM;
 790	return 0;
 791}
 792
 793static void __exit fat_destroy_inodecache(void)
 794{
 795	/*
 796	 * Make sure all delayed rcu free inodes are flushed before we
 797	 * destroy cache.
 798	 */
 799	rcu_barrier();
 800	kmem_cache_destroy(fat_inode_cachep);
 801}
 802
 803static int fat_remount(struct super_block *sb, int *flags, char *data)
 804{
 805	bool new_rdonly;
 806	struct msdos_sb_info *sbi = MSDOS_SB(sb);
 807	*flags |= SB_NODIRATIME | (sbi->options.isvfat ? 0 : SB_NOATIME);
 808
 809	sync_filesystem(sb);
 810
 811	/* make sure we update state on remount. */
 812	new_rdonly = *flags & SB_RDONLY;
 813	if (new_rdonly != sb_rdonly(sb)) {
 814		if (new_rdonly)
 815			fat_set_state(sb, 0, 0);
 816		else
 817			fat_set_state(sb, 1, 1);
 818	}
 819	return 0;
 820}
 821
 822static int fat_statfs(struct dentry *dentry, struct kstatfs *buf)
 823{
 824	struct super_block *sb = dentry->d_sb;
 825	struct msdos_sb_info *sbi = MSDOS_SB(sb);
 826	u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
 827
 828	/* If the count of free cluster is still unknown, counts it here. */
 829	if (sbi->free_clusters == -1 || !sbi->free_clus_valid) {
 830		int err = fat_count_free_clusters(dentry->d_sb);
 831		if (err)
 832			return err;
 833	}
 834
 835	buf->f_type = dentry->d_sb->s_magic;
 836	buf->f_bsize = sbi->cluster_size;
 837	buf->f_blocks = sbi->max_cluster - FAT_START_ENT;
 838	buf->f_bfree = sbi->free_clusters;
 839	buf->f_bavail = sbi->free_clusters;
 840	buf->f_fsid = u64_to_fsid(id);
 
 841	buf->f_namelen =
 842		(sbi->options.isvfat ? FAT_LFN_LEN : 12) * NLS_MAX_CHARSET_SIZE;
 843
 844	return 0;
 845}
 846
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 847static int __fat_write_inode(struct inode *inode, int wait)
 848{
 849	struct super_block *sb = inode->i_sb;
 850	struct msdos_sb_info *sbi = MSDOS_SB(sb);
 851	struct buffer_head *bh;
 852	struct msdos_dir_entry *raw_entry;
 853	loff_t i_pos;
 854	sector_t blocknr;
 855	int err, offset;
 856
 857	if (inode->i_ino == MSDOS_ROOT_INO)
 858		return 0;
 859
 860retry:
 861	i_pos = fat_i_pos_read(sbi, inode);
 862	if (!i_pos)
 863		return 0;
 864
 865	fat_get_blknr_offset(sbi, i_pos, &blocknr, &offset);
 866	bh = sb_bread(sb, blocknr);
 867	if (!bh) {
 868		fat_msg(sb, KERN_ERR, "unable to read inode block "
 869		       "for updating (i_pos %lld)", i_pos);
 870		return -EIO;
 871	}
 872	spin_lock(&sbi->inode_hash_lock);
 873	if (i_pos != MSDOS_I(inode)->i_pos) {
 874		spin_unlock(&sbi->inode_hash_lock);
 875		brelse(bh);
 876		goto retry;
 877	}
 878
 879	raw_entry = &((struct msdos_dir_entry *) (bh->b_data))[offset];
 
 880	if (S_ISDIR(inode->i_mode))
 881		raw_entry->size = 0;
 882	else
 883		raw_entry->size = cpu_to_le32(inode->i_size);
 884	raw_entry->attr = fat_make_attrs(inode);
 885	fat_set_start(raw_entry, MSDOS_I(inode)->i_logstart);
 
 886	fat_time_unix2fat(sbi, &inode->i_mtime, &raw_entry->time,
 887			  &raw_entry->date, NULL);
 888	if (sbi->options.isvfat) {
 889		__le16 atime;
 890		fat_time_unix2fat(sbi, &inode->i_ctime, &raw_entry->ctime,
 891				  &raw_entry->cdate, &raw_entry->ctime_cs);
 892		fat_time_unix2fat(sbi, &inode->i_atime, &atime,
 893				  &raw_entry->adate, NULL);
 894	}
 895	spin_unlock(&sbi->inode_hash_lock);
 896	mark_buffer_dirty(bh);
 897	err = 0;
 898	if (wait)
 899		err = sync_dirty_buffer(bh);
 900	brelse(bh);
 901	return err;
 902}
 903
 904static int fat_write_inode(struct inode *inode, struct writeback_control *wbc)
 905{
 906	int err;
 907
 908	if (inode->i_ino == MSDOS_FSINFO_INO) {
 909		struct super_block *sb = inode->i_sb;
 910
 911		mutex_lock(&MSDOS_SB(sb)->s_lock);
 912		err = fat_clusters_flush(sb);
 913		mutex_unlock(&MSDOS_SB(sb)->s_lock);
 914	} else
 915		err = __fat_write_inode(inode, wbc->sync_mode == WB_SYNC_ALL);
 916
 917	return err;
 918}
 919
 920int fat_sync_inode(struct inode *inode)
 921{
 922	return __fat_write_inode(inode, 1);
 923}
 924
 925EXPORT_SYMBOL_GPL(fat_sync_inode);
 926
 927static int fat_show_options(struct seq_file *m, struct dentry *root);
 928static const struct super_operations fat_sops = {
 929	.alloc_inode	= fat_alloc_inode,
 930	.free_inode	= fat_free_inode,
 931	.write_inode	= fat_write_inode,
 932	.evict_inode	= fat_evict_inode,
 933	.put_super	= fat_put_super,
 934	.statfs		= fat_statfs,
 935	.remount_fs	= fat_remount,
 936
 937	.show_options	= fat_show_options,
 938};
 939
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 940static int fat_show_options(struct seq_file *m, struct dentry *root)
 941{
 942	struct msdos_sb_info *sbi = MSDOS_SB(root->d_sb);
 943	struct fat_mount_options *opts = &sbi->options;
 944	int isvfat = opts->isvfat;
 945
 946	if (!uid_eq(opts->fs_uid, GLOBAL_ROOT_UID))
 947		seq_printf(m, ",uid=%u",
 948				from_kuid_munged(&init_user_ns, opts->fs_uid));
 949	if (!gid_eq(opts->fs_gid, GLOBAL_ROOT_GID))
 950		seq_printf(m, ",gid=%u",
 951				from_kgid_munged(&init_user_ns, opts->fs_gid));
 952	seq_printf(m, ",fmask=%04o", opts->fs_fmask);
 953	seq_printf(m, ",dmask=%04o", opts->fs_dmask);
 954	if (opts->allow_utime)
 955		seq_printf(m, ",allow_utime=%04o", opts->allow_utime);
 956	if (sbi->nls_disk)
 957		/* strip "cp" prefix from displayed option */
 958		seq_printf(m, ",codepage=%s", &sbi->nls_disk->charset[2]);
 959	if (isvfat) {
 960		if (sbi->nls_io)
 961			seq_printf(m, ",iocharset=%s", sbi->nls_io->charset);
 962
 963		switch (opts->shortname) {
 964		case VFAT_SFN_DISPLAY_WIN95 | VFAT_SFN_CREATE_WIN95:
 965			seq_puts(m, ",shortname=win95");
 966			break;
 967		case VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WINNT:
 968			seq_puts(m, ",shortname=winnt");
 969			break;
 970		case VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WIN95:
 971			seq_puts(m, ",shortname=mixed");
 972			break;
 973		case VFAT_SFN_DISPLAY_LOWER | VFAT_SFN_CREATE_WIN95:
 974			seq_puts(m, ",shortname=lower");
 975			break;
 976		default:
 977			seq_puts(m, ",shortname=unknown");
 978			break;
 979		}
 980	}
 981	if (opts->name_check != 'n')
 982		seq_printf(m, ",check=%c", opts->name_check);
 983	if (opts->usefree)
 984		seq_puts(m, ",usefree");
 985	if (opts->quiet)
 986		seq_puts(m, ",quiet");
 987	if (opts->showexec)
 988		seq_puts(m, ",showexec");
 989	if (opts->sys_immutable)
 990		seq_puts(m, ",sys_immutable");
 991	if (!isvfat) {
 992		if (opts->dotsOK)
 993			seq_puts(m, ",dotsOK=yes");
 994		if (opts->nocase)
 995			seq_puts(m, ",nocase");
 996	} else {
 997		if (opts->utf8)
 998			seq_puts(m, ",utf8");
 999		if (opts->unicode_xlate)
1000			seq_puts(m, ",uni_xlate");
1001		if (!opts->numtail)
1002			seq_puts(m, ",nonumtail");
1003		if (opts->rodir)
1004			seq_puts(m, ",rodir");
1005	}
1006	if (opts->flush)
1007		seq_puts(m, ",flush");
1008	if (opts->tz_set) {
1009		if (opts->time_offset)
1010			seq_printf(m, ",time_offset=%d", opts->time_offset);
1011		else
1012			seq_puts(m, ",tz=UTC");
1013	}
1014	if (opts->errors == FAT_ERRORS_CONT)
1015		seq_puts(m, ",errors=continue");
1016	else if (opts->errors == FAT_ERRORS_PANIC)
1017		seq_puts(m, ",errors=panic");
1018	else
1019		seq_puts(m, ",errors=remount-ro");
1020	if (opts->nfs == FAT_NFS_NOSTALE_RO)
1021		seq_puts(m, ",nfs=nostale_ro");
1022	else if (opts->nfs)
1023		seq_puts(m, ",nfs=stale_rw");
1024	if (opts->discard)
1025		seq_puts(m, ",discard");
1026	if (opts->dos1xfloppy)
1027		seq_puts(m, ",dos1xfloppy");
1028
1029	return 0;
1030}
1031
1032enum {
1033	Opt_check_n, Opt_check_r, Opt_check_s, Opt_uid, Opt_gid,
1034	Opt_umask, Opt_dmask, Opt_fmask, Opt_allow_utime, Opt_codepage,
1035	Opt_usefree, Opt_nocase, Opt_quiet, Opt_showexec, Opt_debug,
1036	Opt_immutable, Opt_dots, Opt_nodots,
1037	Opt_charset, Opt_shortname_lower, Opt_shortname_win95,
1038	Opt_shortname_winnt, Opt_shortname_mixed, Opt_utf8_no, Opt_utf8_yes,
1039	Opt_uni_xl_no, Opt_uni_xl_yes, Opt_nonumtail_no, Opt_nonumtail_yes,
1040	Opt_obsolete, Opt_flush, Opt_tz_utc, Opt_rodir, Opt_err_cont,
1041	Opt_err_panic, Opt_err_ro, Opt_discard, Opt_nfs, Opt_time_offset,
1042	Opt_nfs_stale_rw, Opt_nfs_nostale_ro, Opt_err, Opt_dos1xfloppy,
1043};
1044
1045static const match_table_t fat_tokens = {
1046	{Opt_check_r, "check=relaxed"},
1047	{Opt_check_s, "check=strict"},
1048	{Opt_check_n, "check=normal"},
1049	{Opt_check_r, "check=r"},
1050	{Opt_check_s, "check=s"},
1051	{Opt_check_n, "check=n"},
1052	{Opt_uid, "uid=%u"},
1053	{Opt_gid, "gid=%u"},
1054	{Opt_umask, "umask=%o"},
1055	{Opt_dmask, "dmask=%o"},
1056	{Opt_fmask, "fmask=%o"},
1057	{Opt_allow_utime, "allow_utime=%o"},
1058	{Opt_codepage, "codepage=%u"},
1059	{Opt_usefree, "usefree"},
1060	{Opt_nocase, "nocase"},
1061	{Opt_quiet, "quiet"},
1062	{Opt_showexec, "showexec"},
1063	{Opt_debug, "debug"},
1064	{Opt_immutable, "sys_immutable"},
1065	{Opt_flush, "flush"},
1066	{Opt_tz_utc, "tz=UTC"},
1067	{Opt_time_offset, "time_offset=%d"},
1068	{Opt_err_cont, "errors=continue"},
1069	{Opt_err_panic, "errors=panic"},
1070	{Opt_err_ro, "errors=remount-ro"},
1071	{Opt_discard, "discard"},
1072	{Opt_nfs_stale_rw, "nfs"},
1073	{Opt_nfs_stale_rw, "nfs=stale_rw"},
1074	{Opt_nfs_nostale_ro, "nfs=nostale_ro"},
1075	{Opt_dos1xfloppy, "dos1xfloppy"},
1076	{Opt_obsolete, "conv=binary"},
1077	{Opt_obsolete, "conv=text"},
1078	{Opt_obsolete, "conv=auto"},
1079	{Opt_obsolete, "conv=b"},
1080	{Opt_obsolete, "conv=t"},
1081	{Opt_obsolete, "conv=a"},
1082	{Opt_obsolete, "fat=%u"},
1083	{Opt_obsolete, "blocksize=%u"},
1084	{Opt_obsolete, "cvf_format=%20s"},
1085	{Opt_obsolete, "cvf_options=%100s"},
1086	{Opt_obsolete, "posix"},
1087	{Opt_err, NULL},
1088};
1089static const match_table_t msdos_tokens = {
1090	{Opt_nodots, "nodots"},
1091	{Opt_nodots, "dotsOK=no"},
1092	{Opt_dots, "dots"},
1093	{Opt_dots, "dotsOK=yes"},
1094	{Opt_err, NULL}
1095};
1096static const match_table_t vfat_tokens = {
1097	{Opt_charset, "iocharset=%s"},
1098	{Opt_shortname_lower, "shortname=lower"},
1099	{Opt_shortname_win95, "shortname=win95"},
1100	{Opt_shortname_winnt, "shortname=winnt"},
1101	{Opt_shortname_mixed, "shortname=mixed"},
1102	{Opt_utf8_no, "utf8=0"},		/* 0 or no or false */
1103	{Opt_utf8_no, "utf8=no"},
1104	{Opt_utf8_no, "utf8=false"},
1105	{Opt_utf8_yes, "utf8=1"},		/* empty or 1 or yes or true */
1106	{Opt_utf8_yes, "utf8=yes"},
1107	{Opt_utf8_yes, "utf8=true"},
1108	{Opt_utf8_yes, "utf8"},
1109	{Opt_uni_xl_no, "uni_xlate=0"},		/* 0 or no or false */
1110	{Opt_uni_xl_no, "uni_xlate=no"},
1111	{Opt_uni_xl_no, "uni_xlate=false"},
1112	{Opt_uni_xl_yes, "uni_xlate=1"},	/* empty or 1 or yes or true */
1113	{Opt_uni_xl_yes, "uni_xlate=yes"},
1114	{Opt_uni_xl_yes, "uni_xlate=true"},
1115	{Opt_uni_xl_yes, "uni_xlate"},
1116	{Opt_nonumtail_no, "nonumtail=0"},	/* 0 or no or false */
1117	{Opt_nonumtail_no, "nonumtail=no"},
1118	{Opt_nonumtail_no, "nonumtail=false"},
1119	{Opt_nonumtail_yes, "nonumtail=1"},	/* empty or 1 or yes or true */
1120	{Opt_nonumtail_yes, "nonumtail=yes"},
1121	{Opt_nonumtail_yes, "nonumtail=true"},
1122	{Opt_nonumtail_yes, "nonumtail"},
1123	{Opt_rodir, "rodir"},
1124	{Opt_err, NULL}
1125};
1126
1127static int parse_options(struct super_block *sb, char *options, int is_vfat,
1128			 int silent, int *debug, struct fat_mount_options *opts)
1129{
1130	char *p;
1131	substring_t args[MAX_OPT_ARGS];
1132	int option;
1133	char *iocharset;
1134
1135	opts->isvfat = is_vfat;
1136
1137	opts->fs_uid = current_uid();
1138	opts->fs_gid = current_gid();
1139	opts->fs_fmask = opts->fs_dmask = current_umask();
1140	opts->allow_utime = -1;
1141	opts->codepage = fat_default_codepage;
1142	fat_reset_iocharset(opts);
1143	if (is_vfat) {
1144		opts->shortname = VFAT_SFN_DISPLAY_WINNT|VFAT_SFN_CREATE_WIN95;
1145		opts->rodir = 0;
1146	} else {
1147		opts->shortname = 0;
1148		opts->rodir = 1;
1149	}
1150	opts->name_check = 'n';
1151	opts->quiet = opts->showexec = opts->sys_immutable = opts->dotsOK =  0;
1152	opts->unicode_xlate = 0;
1153	opts->numtail = 1;
1154	opts->usefree = opts->nocase = 0;
1155	opts->tz_set = 0;
1156	opts->nfs = 0;
1157	opts->errors = FAT_ERRORS_RO;
1158	*debug = 0;
1159
1160	opts->utf8 = IS_ENABLED(CONFIG_FAT_DEFAULT_UTF8) && is_vfat;
1161
1162	if (!options)
1163		goto out;
1164
1165	while ((p = strsep(&options, ",")) != NULL) {
1166		int token;
1167		if (!*p)
1168			continue;
1169
1170		token = match_token(p, fat_tokens, args);
1171		if (token == Opt_err) {
1172			if (is_vfat)
1173				token = match_token(p, vfat_tokens, args);
1174			else
1175				token = match_token(p, msdos_tokens, args);
1176		}
1177		switch (token) {
1178		case Opt_check_s:
1179			opts->name_check = 's';
1180			break;
1181		case Opt_check_r:
1182			opts->name_check = 'r';
1183			break;
1184		case Opt_check_n:
1185			opts->name_check = 'n';
1186			break;
1187		case Opt_usefree:
1188			opts->usefree = 1;
1189			break;
1190		case Opt_nocase:
1191			if (!is_vfat)
1192				opts->nocase = 1;
1193			else {
1194				/* for backward compatibility */
1195				opts->shortname = VFAT_SFN_DISPLAY_WIN95
1196					| VFAT_SFN_CREATE_WIN95;
1197			}
1198			break;
1199		case Opt_quiet:
1200			opts->quiet = 1;
1201			break;
1202		case Opt_showexec:
1203			opts->showexec = 1;
1204			break;
1205		case Opt_debug:
1206			*debug = 1;
1207			break;
1208		case Opt_immutable:
1209			opts->sys_immutable = 1;
1210			break;
1211		case Opt_uid:
1212			if (match_int(&args[0], &option))
1213				return -EINVAL;
1214			opts->fs_uid = make_kuid(current_user_ns(), option);
1215			if (!uid_valid(opts->fs_uid))
1216				return -EINVAL;
1217			break;
1218		case Opt_gid:
1219			if (match_int(&args[0], &option))
1220				return -EINVAL;
1221			opts->fs_gid = make_kgid(current_user_ns(), option);
1222			if (!gid_valid(opts->fs_gid))
1223				return -EINVAL;
1224			break;
1225		case Opt_umask:
1226			if (match_octal(&args[0], &option))
1227				return -EINVAL;
1228			opts->fs_fmask = opts->fs_dmask = option;
1229			break;
1230		case Opt_dmask:
1231			if (match_octal(&args[0], &option))
1232				return -EINVAL;
1233			opts->fs_dmask = option;
1234			break;
1235		case Opt_fmask:
1236			if (match_octal(&args[0], &option))
1237				return -EINVAL;
1238			opts->fs_fmask = option;
1239			break;
1240		case Opt_allow_utime:
1241			if (match_octal(&args[0], &option))
1242				return -EINVAL;
1243			opts->allow_utime = option & (S_IWGRP | S_IWOTH);
1244			break;
1245		case Opt_codepage:
1246			if (match_int(&args[0], &option))
1247				return -EINVAL;
1248			opts->codepage = option;
1249			break;
1250		case Opt_flush:
1251			opts->flush = 1;
1252			break;
1253		case Opt_time_offset:
1254			if (match_int(&args[0], &option))
1255				return -EINVAL;
1256			/*
1257			 * GMT+-12 zones may have DST corrections so at least
1258			 * 13 hours difference is needed. Make the limit 24
1259			 * just in case someone invents something unusual.
1260			 */
1261			if (option < -24 * 60 || option > 24 * 60)
1262				return -EINVAL;
1263			opts->tz_set = 1;
1264			opts->time_offset = option;
1265			break;
1266		case Opt_tz_utc:
1267			opts->tz_set = 1;
1268			opts->time_offset = 0;
1269			break;
1270		case Opt_err_cont:
1271			opts->errors = FAT_ERRORS_CONT;
1272			break;
1273		case Opt_err_panic:
1274			opts->errors = FAT_ERRORS_PANIC;
1275			break;
1276		case Opt_err_ro:
1277			opts->errors = FAT_ERRORS_RO;
1278			break;
1279		case Opt_nfs_stale_rw:
1280			opts->nfs = FAT_NFS_STALE_RW;
1281			break;
1282		case Opt_nfs_nostale_ro:
1283			opts->nfs = FAT_NFS_NOSTALE_RO;
1284			break;
1285		case Opt_dos1xfloppy:
1286			opts->dos1xfloppy = 1;
1287			break;
1288
1289		/* msdos specific */
1290		case Opt_dots:
1291			opts->dotsOK = 1;
1292			break;
1293		case Opt_nodots:
1294			opts->dotsOK = 0;
1295			break;
1296
1297		/* vfat specific */
1298		case Opt_charset:
1299			fat_reset_iocharset(opts);
 
1300			iocharset = match_strdup(&args[0]);
1301			if (!iocharset)
1302				return -ENOMEM;
1303			opts->iocharset = iocharset;
1304			break;
1305		case Opt_shortname_lower:
1306			opts->shortname = VFAT_SFN_DISPLAY_LOWER
1307					| VFAT_SFN_CREATE_WIN95;
1308			break;
1309		case Opt_shortname_win95:
1310			opts->shortname = VFAT_SFN_DISPLAY_WIN95
1311					| VFAT_SFN_CREATE_WIN95;
1312			break;
1313		case Opt_shortname_winnt:
1314			opts->shortname = VFAT_SFN_DISPLAY_WINNT
1315					| VFAT_SFN_CREATE_WINNT;
1316			break;
1317		case Opt_shortname_mixed:
1318			opts->shortname = VFAT_SFN_DISPLAY_WINNT
1319					| VFAT_SFN_CREATE_WIN95;
1320			break;
1321		case Opt_utf8_no:		/* 0 or no or false */
1322			opts->utf8 = 0;
1323			break;
1324		case Opt_utf8_yes:		/* empty or 1 or yes or true */
1325			opts->utf8 = 1;
1326			break;
1327		case Opt_uni_xl_no:		/* 0 or no or false */
1328			opts->unicode_xlate = 0;
1329			break;
1330		case Opt_uni_xl_yes:		/* empty or 1 or yes or true */
1331			opts->unicode_xlate = 1;
1332			break;
1333		case Opt_nonumtail_no:		/* 0 or no or false */
1334			opts->numtail = 1;	/* negated option */
1335			break;
1336		case Opt_nonumtail_yes:		/* empty or 1 or yes or true */
1337			opts->numtail = 0;	/* negated option */
1338			break;
1339		case Opt_rodir:
1340			opts->rodir = 1;
1341			break;
1342		case Opt_discard:
1343			opts->discard = 1;
1344			break;
1345
1346		/* obsolete mount options */
1347		case Opt_obsolete:
1348			fat_msg(sb, KERN_INFO, "\"%s\" option is obsolete, "
1349			       "not supported now", p);
1350			break;
1351		/* unknown option */
1352		default:
1353			if (!silent) {
1354				fat_msg(sb, KERN_ERR,
1355				       "Unrecognized mount option \"%s\" "
1356				       "or missing value", p);
1357			}
1358			return -EINVAL;
1359		}
1360	}
1361
1362out:
1363	/* UTF-8 doesn't provide FAT semantics */
1364	if (!strcmp(opts->iocharset, "utf8")) {
1365		fat_msg(sb, KERN_WARNING, "utf8 is not a recommended IO charset"
1366		       " for FAT filesystems, filesystem will be "
1367		       "case sensitive!");
1368	}
1369
1370	/* If user doesn't specify allow_utime, it's initialized from dmask. */
1371	if (opts->allow_utime == (unsigned short)-1)
1372		opts->allow_utime = ~opts->fs_dmask & (S_IWGRP | S_IWOTH);
1373	if (opts->unicode_xlate)
1374		opts->utf8 = 0;
1375	if (opts->nfs == FAT_NFS_NOSTALE_RO) {
1376		sb->s_flags |= SB_RDONLY;
1377		sb->s_export_op = &fat_export_ops_nostale;
1378	}
1379
1380	return 0;
1381}
1382
1383static int fat_read_root(struct inode *inode)
1384{
1385	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 
1386	int error;
1387
1388	MSDOS_I(inode)->i_pos = MSDOS_ROOT_INO;
1389	inode->i_uid = sbi->options.fs_uid;
1390	inode->i_gid = sbi->options.fs_gid;
1391	inode_inc_iversion(inode);
1392	inode->i_generation = 0;
1393	inode->i_mode = fat_make_mode(sbi, ATTR_DIR, S_IRWXUGO);
1394	inode->i_op = sbi->dir_ops;
1395	inode->i_fop = &fat_dir_operations;
1396	if (is_fat32(sbi)) {
1397		MSDOS_I(inode)->i_start = sbi->root_cluster;
1398		error = fat_calc_dir_size(inode);
1399		if (error < 0)
1400			return error;
1401	} else {
1402		MSDOS_I(inode)->i_start = 0;
1403		inode->i_size = sbi->dir_entries * sizeof(struct msdos_dir_entry);
1404	}
1405	inode->i_blocks = ((inode->i_size + (sbi->cluster_size - 1))
1406			   & ~((loff_t)sbi->cluster_size - 1)) >> 9;
1407	MSDOS_I(inode)->i_logstart = 0;
1408	MSDOS_I(inode)->mmu_private = inode->i_size;
1409
1410	fat_save_attrs(inode, ATTR_DIR);
1411	inode->i_mtime.tv_sec = inode->i_atime.tv_sec = inode->i_ctime.tv_sec = 0;
1412	inode->i_mtime.tv_nsec = inode->i_atime.tv_nsec = inode->i_ctime.tv_nsec = 0;
1413	set_nlink(inode, fat_subdirs(inode)+2);
1414
1415	return 0;
1416}
1417
1418static unsigned long calc_fat_clusters(struct super_block *sb)
1419{
1420	struct msdos_sb_info *sbi = MSDOS_SB(sb);
1421
1422	/* Divide first to avoid overflow */
1423	if (!is_fat12(sbi)) {
1424		unsigned long ent_per_sec = sb->s_blocksize * 8 / sbi->fat_bits;
1425		return ent_per_sec * sbi->fat_length;
1426	}
1427
1428	return sbi->fat_length * sb->s_blocksize * 8 / sbi->fat_bits;
1429}
1430
1431static bool fat_bpb_is_zero(struct fat_boot_sector *b)
1432{
1433	if (get_unaligned_le16(&b->sector_size))
1434		return false;
1435	if (b->sec_per_clus)
1436		return false;
1437	if (b->reserved)
1438		return false;
1439	if (b->fats)
1440		return false;
1441	if (get_unaligned_le16(&b->dir_entries))
1442		return false;
1443	if (get_unaligned_le16(&b->sectors))
1444		return false;
1445	if (b->media)
1446		return false;
1447	if (b->fat_length)
1448		return false;
1449	if (b->secs_track)
1450		return false;
1451	if (b->heads)
1452		return false;
1453	return true;
1454}
1455
1456static int fat_read_bpb(struct super_block *sb, struct fat_boot_sector *b,
1457	int silent, struct fat_bios_param_block *bpb)
1458{
1459	int error = -EINVAL;
1460
1461	/* Read in BPB ... */
1462	memset(bpb, 0, sizeof(*bpb));
1463	bpb->fat_sector_size = get_unaligned_le16(&b->sector_size);
1464	bpb->fat_sec_per_clus = b->sec_per_clus;
1465	bpb->fat_reserved = le16_to_cpu(b->reserved);
1466	bpb->fat_fats = b->fats;
1467	bpb->fat_dir_entries = get_unaligned_le16(&b->dir_entries);
1468	bpb->fat_sectors = get_unaligned_le16(&b->sectors);
1469	bpb->fat_fat_length = le16_to_cpu(b->fat_length);
1470	bpb->fat_total_sect = le32_to_cpu(b->total_sect);
1471
1472	bpb->fat16_state = b->fat16.state;
1473	bpb->fat16_vol_id = get_unaligned_le32(b->fat16.vol_id);
1474
1475	bpb->fat32_length = le32_to_cpu(b->fat32.length);
1476	bpb->fat32_root_cluster = le32_to_cpu(b->fat32.root_cluster);
1477	bpb->fat32_info_sector = le16_to_cpu(b->fat32.info_sector);
1478	bpb->fat32_state = b->fat32.state;
1479	bpb->fat32_vol_id = get_unaligned_le32(b->fat32.vol_id);
1480
1481	/* Validate this looks like a FAT filesystem BPB */
1482	if (!bpb->fat_reserved) {
1483		if (!silent)
1484			fat_msg(sb, KERN_ERR,
1485				"bogus number of reserved sectors");
1486		goto out;
1487	}
1488	if (!bpb->fat_fats) {
1489		if (!silent)
1490			fat_msg(sb, KERN_ERR, "bogus number of FAT structure");
1491		goto out;
1492	}
1493
1494	/*
1495	 * Earlier we checked here that b->secs_track and b->head are nonzero,
1496	 * but it turns out valid FAT filesystems can have zero there.
1497	 */
1498
1499	if (!fat_valid_media(b->media)) {
1500		if (!silent)
1501			fat_msg(sb, KERN_ERR, "invalid media value (0x%02x)",
1502				(unsigned)b->media);
1503		goto out;
1504	}
1505
1506	if (!is_power_of_2(bpb->fat_sector_size)
1507	    || (bpb->fat_sector_size < 512)
1508	    || (bpb->fat_sector_size > 4096)) {
1509		if (!silent)
1510			fat_msg(sb, KERN_ERR, "bogus logical sector size %u",
1511			       (unsigned)bpb->fat_sector_size);
1512		goto out;
1513	}
1514
1515	if (!is_power_of_2(bpb->fat_sec_per_clus)) {
1516		if (!silent)
1517			fat_msg(sb, KERN_ERR, "bogus sectors per cluster %u",
1518				(unsigned)bpb->fat_sec_per_clus);
1519		goto out;
1520	}
1521
1522	if (bpb->fat_fat_length == 0 && bpb->fat32_length == 0) {
1523		if (!silent)
1524			fat_msg(sb, KERN_ERR, "bogus number of FAT sectors");
1525		goto out;
1526	}
1527
1528	error = 0;
1529
1530out:
1531	return error;
1532}
1533
1534static int fat_read_static_bpb(struct super_block *sb,
1535	struct fat_boot_sector *b, int silent,
1536	struct fat_bios_param_block *bpb)
1537{
1538	static const char *notdos1x = "This doesn't look like a DOS 1.x volume";
1539
1540	struct fat_floppy_defaults *fdefaults = NULL;
1541	int error = -EINVAL;
1542	sector_t bd_sects;
1543	unsigned i;
1544
1545	bd_sects = i_size_read(sb->s_bdev->bd_inode) / SECTOR_SIZE;
1546
1547	/* 16-bit DOS 1.x reliably wrote bootstrap short-jmp code */
1548	if (b->ignored[0] != 0xeb || b->ignored[2] != 0x90) {
1549		if (!silent)
1550			fat_msg(sb, KERN_ERR,
1551				"%s; no bootstrapping code", notdos1x);
1552		goto out;
1553	}
1554
1555	/*
1556	 * If any value in this region is non-zero, it isn't archaic
1557	 * DOS.
1558	 */
1559	if (!fat_bpb_is_zero(b)) {
1560		if (!silent)
1561			fat_msg(sb, KERN_ERR,
1562				"%s; DOS 2.x BPB is non-zero", notdos1x);
1563		goto out;
1564	}
1565
1566	for (i = 0; i < ARRAY_SIZE(floppy_defaults); i++) {
1567		if (floppy_defaults[i].nr_sectors == bd_sects) {
1568			fdefaults = &floppy_defaults[i];
1569			break;
1570		}
1571	}
1572
1573	if (fdefaults == NULL) {
1574		if (!silent)
1575			fat_msg(sb, KERN_WARNING,
1576				"This looks like a DOS 1.x volume, but isn't a recognized floppy size (%llu sectors)",
1577				(u64)bd_sects);
1578		goto out;
1579	}
1580
1581	if (!silent)
1582		fat_msg(sb, KERN_INFO,
1583			"This looks like a DOS 1.x volume; assuming default BPB values");
1584
1585	memset(bpb, 0, sizeof(*bpb));
1586	bpb->fat_sector_size = SECTOR_SIZE;
1587	bpb->fat_sec_per_clus = fdefaults->sec_per_clus;
1588	bpb->fat_reserved = 1;
1589	bpb->fat_fats = 2;
1590	bpb->fat_dir_entries = fdefaults->dir_entries;
1591	bpb->fat_sectors = fdefaults->nr_sectors;
1592	bpb->fat_fat_length = fdefaults->fat_length;
1593
1594	error = 0;
1595
1596out:
1597	return error;
1598}
1599
1600/*
1601 * Read the super block of an MS-DOS FS.
1602 */
1603int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat,
1604		   void (*setup)(struct super_block *))
1605{
1606	struct inode *root_inode = NULL, *fat_inode = NULL;
1607	struct inode *fsinfo_inode = NULL;
1608	struct buffer_head *bh;
1609	struct fat_bios_param_block bpb;
1610	struct msdos_sb_info *sbi;
1611	u16 logical_sector_size;
1612	u32 total_sectors, total_clusters, fat_clusters, rootdir_sectors;
1613	int debug;
 
1614	long error;
1615	char buf[50];
1616	struct timespec64 ts;
1617
1618	/*
1619	 * GFP_KERNEL is ok here, because while we do hold the
1620	 * superblock lock, memory pressure can't call back into
1621	 * the filesystem, since we're only just about to mount
1622	 * it and have no inodes etc active!
1623	 */
1624	sbi = kzalloc(sizeof(struct msdos_sb_info), GFP_KERNEL);
1625	if (!sbi)
1626		return -ENOMEM;
1627	sb->s_fs_info = sbi;
1628
1629	sb->s_flags |= SB_NODIRATIME;
1630	sb->s_magic = MSDOS_SUPER_MAGIC;
1631	sb->s_op = &fat_sops;
1632	sb->s_export_op = &fat_export_ops;
1633	/*
1634	 * fat timestamps are complex and truncated by fat itself, so
1635	 * we set 1 here to be fast
1636	 */
1637	sb->s_time_gran = 1;
1638	mutex_init(&sbi->nfs_build_inode_lock);
1639	ratelimit_state_init(&sbi->ratelimit, DEFAULT_RATELIMIT_INTERVAL,
1640			     DEFAULT_RATELIMIT_BURST);
1641
1642	error = parse_options(sb, data, isvfat, silent, &debug, &sbi->options);
1643	if (error)
1644		goto out_fail;
1645
1646	setup(sb); /* flavour-specific stuff that needs options */
1647
1648	error = -EIO;
1649	sb_min_blocksize(sb, 512);
1650	bh = sb_bread(sb, 0);
1651	if (bh == NULL) {
1652		fat_msg(sb, KERN_ERR, "unable to read boot sector");
1653		goto out_fail;
1654	}
1655
1656	error = fat_read_bpb(sb, (struct fat_boot_sector *)bh->b_data, silent,
1657		&bpb);
1658	if (error == -EINVAL && sbi->options.dos1xfloppy)
1659		error = fat_read_static_bpb(sb,
1660			(struct fat_boot_sector *)bh->b_data, silent, &bpb);
1661	brelse(bh);
1662
1663	if (error == -EINVAL)
1664		goto out_invalid;
1665	else if (error)
1666		goto out_fail;
 
 
 
 
 
1667
1668	logical_sector_size = bpb.fat_sector_size;
1669	sbi->sec_per_clus = bpb.fat_sec_per_clus;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1670
1671	error = -EIO;
1672	if (logical_sector_size < sb->s_blocksize) {
1673		fat_msg(sb, KERN_ERR, "logical sector size too small for device"
1674		       " (logical sector size = %u)", logical_sector_size);
 
1675		goto out_fail;
1676	}
1677
1678	if (logical_sector_size > sb->s_blocksize) {
1679		struct buffer_head *bh_resize;
1680
1681		if (!sb_set_blocksize(sb, logical_sector_size)) {
1682			fat_msg(sb, KERN_ERR, "unable to set blocksize %u",
1683			       logical_sector_size);
1684			goto out_fail;
1685		}
1686
1687		/* Verify that the larger boot sector is fully readable */
1688		bh_resize = sb_bread(sb, 0);
1689		if (bh_resize == NULL) {
1690			fat_msg(sb, KERN_ERR, "unable to read boot sector"
1691			       " (logical sector size = %lu)",
1692			       sb->s_blocksize);
1693			goto out_fail;
1694		}
1695		brelse(bh_resize);
1696	}
1697
1698	mutex_init(&sbi->s_lock);
1699	sbi->cluster_size = sb->s_blocksize * sbi->sec_per_clus;
1700	sbi->cluster_bits = ffs(sbi->cluster_size) - 1;
1701	sbi->fats = bpb.fat_fats;
1702	sbi->fat_bits = 0;		/* Don't know yet */
1703	sbi->fat_start = bpb.fat_reserved;
1704	sbi->fat_length = bpb.fat_fat_length;
1705	sbi->root_cluster = 0;
1706	sbi->free_clusters = -1;	/* Don't know yet */
1707	sbi->free_clus_valid = 0;
1708	sbi->prev_free = FAT_START_ENT;
1709	sb->s_maxbytes = 0xffffffff;
1710	fat_time_fat2unix(sbi, &ts, 0, cpu_to_le16(FAT_DATE_MIN), 0);
1711	sb->s_time_min = ts.tv_sec;
1712
1713	fat_time_fat2unix(sbi, &ts, cpu_to_le16(FAT_TIME_MAX),
1714			  cpu_to_le16(FAT_DATE_MAX), 0);
1715	sb->s_time_max = ts.tv_sec;
1716
1717	if (!sbi->fat_length && bpb.fat32_length) {
1718		struct fat_boot_fsinfo *fsinfo;
1719		struct buffer_head *fsinfo_bh;
1720
1721		/* Must be FAT32 */
1722		sbi->fat_bits = 32;
1723		sbi->fat_length = bpb.fat32_length;
1724		sbi->root_cluster = bpb.fat32_root_cluster;
1725
1726		/* MC - if info_sector is 0, don't multiply by 0 */
1727		sbi->fsinfo_sector = bpb.fat32_info_sector;
1728		if (sbi->fsinfo_sector == 0)
1729			sbi->fsinfo_sector = 1;
1730
1731		fsinfo_bh = sb_bread(sb, sbi->fsinfo_sector);
1732		if (fsinfo_bh == NULL) {
1733			fat_msg(sb, KERN_ERR, "bread failed, FSINFO block"
1734			       " (sector = %lu)", sbi->fsinfo_sector);
 
1735			goto out_fail;
1736		}
1737
1738		fsinfo = (struct fat_boot_fsinfo *)fsinfo_bh->b_data;
1739		if (!IS_FSINFO(fsinfo)) {
1740			fat_msg(sb, KERN_WARNING, "Invalid FSINFO signature: "
1741			       "0x%08x, 0x%08x (sector = %lu)",
1742			       le32_to_cpu(fsinfo->signature1),
1743			       le32_to_cpu(fsinfo->signature2),
1744			       sbi->fsinfo_sector);
1745		} else {
1746			if (sbi->options.usefree)
1747				sbi->free_clus_valid = 1;
1748			sbi->free_clusters = le32_to_cpu(fsinfo->free_clusters);
1749			sbi->prev_free = le32_to_cpu(fsinfo->next_cluster);
1750		}
1751
1752		brelse(fsinfo_bh);
1753	}
1754
1755	/* interpret volume ID as a little endian 32 bit integer */
1756	if (is_fat32(sbi))
1757		sbi->vol_id = bpb.fat32_vol_id;
1758	else /* fat 16 or 12 */
1759		sbi->vol_id = bpb.fat16_vol_id;
1760
1761	sbi->dir_per_block = sb->s_blocksize / sizeof(struct msdos_dir_entry);
1762	sbi->dir_per_block_bits = ffs(sbi->dir_per_block) - 1;
1763
1764	sbi->dir_start = sbi->fat_start + sbi->fats * sbi->fat_length;
1765	sbi->dir_entries = bpb.fat_dir_entries;
1766	if (sbi->dir_entries & (sbi->dir_per_block - 1)) {
1767		if (!silent)
1768			fat_msg(sb, KERN_ERR, "bogus number of directory entries"
1769			       " (%u)", sbi->dir_entries);
 
1770		goto out_invalid;
1771	}
1772
1773	rootdir_sectors = sbi->dir_entries
1774		* sizeof(struct msdos_dir_entry) / sb->s_blocksize;
1775	sbi->data_start = sbi->dir_start + rootdir_sectors;
1776	total_sectors = bpb.fat_sectors;
1777	if (total_sectors == 0)
1778		total_sectors = bpb.fat_total_sect;
1779
1780	total_clusters = (total_sectors - sbi->data_start) / sbi->sec_per_clus;
1781
1782	if (!is_fat32(sbi))
1783		sbi->fat_bits = (total_clusters > MAX_FAT12) ? 16 : 12;
1784
1785	/* some OSes set FAT_STATE_DIRTY and clean it on unmount. */
1786	if (is_fat32(sbi))
1787		sbi->dirty = bpb.fat32_state & FAT_STATE_DIRTY;
1788	else /* fat 16 or 12 */
1789		sbi->dirty = bpb.fat16_state & FAT_STATE_DIRTY;
1790
1791	/* check that FAT table does not overflow */
1792	fat_clusters = calc_fat_clusters(sb);
1793	total_clusters = min(total_clusters, fat_clusters - FAT_START_ENT);
1794	if (total_clusters > max_fat(sb)) {
1795		if (!silent)
1796			fat_msg(sb, KERN_ERR, "count of clusters too big (%u)",
1797			       total_clusters);
 
1798		goto out_invalid;
1799	}
1800
1801	sbi->max_cluster = total_clusters + FAT_START_ENT;
1802	/* check the free_clusters, it's not necessarily correct */
1803	if (sbi->free_clusters != -1 && sbi->free_clusters > total_clusters)
1804		sbi->free_clusters = -1;
1805	/* check the prev_free, it's not necessarily correct */
1806	sbi->prev_free %= sbi->max_cluster;
1807	if (sbi->prev_free < FAT_START_ENT)
1808		sbi->prev_free = FAT_START_ENT;
1809
 
 
1810	/* set up enough so that it can read an inode */
1811	fat_hash_init(sb);
1812	dir_hash_init(sb);
1813	fat_ent_access_init(sb);
1814
1815	/*
1816	 * The low byte of the first FAT entry must have the same value as
1817	 * the media field of the boot sector. But in real world, too many
1818	 * devices are writing wrong values. So, removed that validity check.
1819	 *
1820	 * The removed check compared the first FAT entry to a value dependent
1821	 * on the media field like this:
1822	 * == (0x0F00 | media), for FAT12
1823	 * == (0XFF00 | media), for FAT16
1824	 * == (0x0FFFFF | media), for FAT32
1825	 */
1826
1827	error = -EINVAL;
1828	sprintf(buf, "cp%d", sbi->options.codepage);
1829	sbi->nls_disk = load_nls(buf);
1830	if (!sbi->nls_disk) {
1831		fat_msg(sb, KERN_ERR, "codepage %s not found", buf);
1832		goto out_fail;
1833	}
1834
1835	/* FIXME: utf8 is using iocharset for upper/lower conversion */
1836	if (sbi->options.isvfat) {
1837		sbi->nls_io = load_nls(sbi->options.iocharset);
1838		if (!sbi->nls_io) {
1839			fat_msg(sb, KERN_ERR, "IO charset %s not found",
1840			       sbi->options.iocharset);
1841			goto out_fail;
1842		}
1843	}
1844
1845	error = -ENOMEM;
1846	fat_inode = new_inode(sb);
1847	if (!fat_inode)
1848		goto out_fail;
 
1849	sbi->fat_inode = fat_inode;
1850
1851	fsinfo_inode = new_inode(sb);
1852	if (!fsinfo_inode)
1853		goto out_fail;
1854	fsinfo_inode->i_ino = MSDOS_FSINFO_INO;
1855	sbi->fsinfo_inode = fsinfo_inode;
1856	insert_inode_hash(fsinfo_inode);
1857
1858	root_inode = new_inode(sb);
1859	if (!root_inode)
1860		goto out_fail;
1861	root_inode->i_ino = MSDOS_ROOT_INO;
1862	inode_set_iversion(root_inode, 1);
1863	error = fat_read_root(root_inode);
1864	if (error < 0) {
1865		iput(root_inode);
1866		goto out_fail;
1867	}
1868	error = -ENOMEM;
1869	insert_inode_hash(root_inode);
1870	fat_attach(root_inode, 0);
1871	sb->s_root = d_make_root(root_inode);
1872	if (!sb->s_root) {
1873		fat_msg(sb, KERN_ERR, "get root inode failed");
1874		goto out_fail;
1875	}
1876
1877	if (sbi->options.discard) {
1878		struct request_queue *q = bdev_get_queue(sb->s_bdev);
1879		if (!blk_queue_discard(q))
1880			fat_msg(sb, KERN_WARNING,
1881					"mounting with \"discard\" option, but "
1882					"the device does not support discard");
1883	}
1884
1885	fat_set_state(sb, 1, 0);
1886	return 0;
1887
1888out_invalid:
1889	error = -EINVAL;
1890	if (!silent)
1891		fat_msg(sb, KERN_INFO, "Can't find a valid FAT filesystem");
1892
1893out_fail:
1894	if (fsinfo_inode)
1895		iput(fsinfo_inode);
1896	if (fat_inode)
1897		iput(fat_inode);
1898	unload_nls(sbi->nls_io);
1899	unload_nls(sbi->nls_disk);
1900	fat_reset_iocharset(&sbi->options);
 
1901	sb->s_fs_info = NULL;
1902	kfree(sbi);
1903	return error;
1904}
1905
1906EXPORT_SYMBOL_GPL(fat_fill_super);
1907
1908/*
1909 * helper function for fat_flush_inodes.  This writes both the inode
1910 * and the file data blocks, waiting for in flight data blocks before
1911 * the start of the call.  It does not wait for any io started
1912 * during the call
1913 */
1914static int writeback_inode(struct inode *inode)
1915{
1916
1917	int ret;
1918
1919	/* if we used wait=1, sync_inode_metadata waits for the io for the
1920	* inode to finish.  So wait=0 is sent down to sync_inode_metadata
 
 
 
 
1921	* and filemap_fdatawrite is used for the data blocks
1922	*/
1923	ret = sync_inode_metadata(inode, 0);
1924	if (!ret)
1925		ret = filemap_fdatawrite(inode->i_mapping);
1926	return ret;
1927}
1928
1929/*
1930 * write data and metadata corresponding to i1 and i2.  The io is
1931 * started but we do not wait for any of it to finish.
1932 *
1933 * filemap_flush is used for the block device, so if there is a dirty
1934 * page for a block already in flight, we will not wait and start the
1935 * io over again
1936 */
1937int fat_flush_inodes(struct super_block *sb, struct inode *i1, struct inode *i2)
1938{
1939	int ret = 0;
1940	if (!MSDOS_SB(sb)->options.flush)
1941		return 0;
1942	if (i1)
1943		ret = writeback_inode(i1);
1944	if (!ret && i2)
1945		ret = writeback_inode(i2);
1946	if (!ret) {
1947		struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping;
1948		ret = filemap_flush(mapping);
1949	}
1950	return ret;
1951}
1952EXPORT_SYMBOL_GPL(fat_flush_inodes);
1953
1954static int __init init_fat_fs(void)
1955{
1956	int err;
1957
1958	err = fat_cache_init();
1959	if (err)
1960		return err;
1961
1962	err = fat_init_inodecache();
1963	if (err)
1964		goto failed;
1965
1966	return 0;
1967
1968failed:
1969	fat_cache_destroy();
1970	return err;
1971}
1972
1973static void __exit exit_fat_fs(void)
1974{
1975	fat_cache_destroy();
1976	fat_destroy_inodecache();
1977}
1978
1979module_init(init_fat_fs)
1980module_exit(exit_fat_fs)
1981
1982MODULE_LICENSE("GPL");