inode.c

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 *  linux/fs/fat/inode.c
   4 *
   5 *  Written 1992,1993 by Werner Almesberger
   6 *  VFAT extensions by Gordon Chaffee, merged with msdos fs by Henrik Storner
   7 *  Rewritten for the constant inumbers support by Al Viro
   8 *
   9 *  Fixes:
  10 *
  11 *	Max Cohan: Fixed invalid FSINFO offset when info_sector is 0
  12 */
  13
  14#include <linux/module.h>
  15#include <linux/pagemap.h>
  16#include <linux/mpage.h>
  17#include <linux/vfs.h>
  18#include <linux/seq_file.h>
  19#include <linux/uio.h>
  20#include <linux/blkdev.h>
  21#include <linux/backing-dev.h>
  22#include <linux/unaligned.h>
  23#include <linux/random.h>
  24#include <linux/iversion.h>
  25#include <linux/fs_struct.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_writepages(struct address_space *mapping,
 198			  struct writeback_control *wbc)
 199{
 200	return mpage_writepages(mapping, wbc, fat_get_block);
 201}
 202
 203static int fat_read_folio(struct file *file, struct folio *folio)
 204{
 205	return mpage_read_folio(folio, fat_get_block);
 206}
 207
 208static void fat_readahead(struct readahead_control *rac)
 209{
 210	mpage_readahead(rac, fat_get_block);
 211}
 212
 213static void fat_write_failed(struct address_space *mapping, loff_t to)
 214{
 215	struct inode *inode = mapping->host;
 216
 217	if (to > inode->i_size) {
 218		truncate_pagecache(inode, inode->i_size);
 219		fat_truncate_blocks(inode, inode->i_size);
 220	}
 221}
 222
 223static int fat_write_begin(const struct kiocb *iocb,
 224			   struct address_space *mapping,
 225			   loff_t pos, unsigned len,
 226			   struct folio **foliop, void **fsdata)
 227{
 228	int err;
 229
 230	err = cont_write_begin(iocb, mapping, pos, len,
 231				foliop, fsdata, fat_get_block,
 232				&MSDOS_I(mapping->host)->mmu_private);
 233	if (err < 0)
 234		fat_write_failed(mapping, pos + len);
 235	return err;
 236}
 237
 238static int fat_write_end(const struct kiocb *iocb,
 239			 struct address_space *mapping,
 240			 loff_t pos, unsigned len, unsigned copied,
 241			 struct folio *folio, void *fsdata)
 242{
 243	struct inode *inode = mapping->host;
 244	int err;
 245	err = generic_write_end(iocb, mapping, pos, len, copied, folio, fsdata);
 246	if (err < len)
 247		fat_write_failed(mapping, pos + len);
 248	if (!(err < 0) && !(MSDOS_I(inode)->i_attrs & ATTR_ARCH)) {
 249		fat_truncate_time(inode, NULL, S_CTIME|S_MTIME);
 250		MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
 251		mark_inode_dirty(inode);
 252	}
 253	return err;
 254}
 255
 256static ssize_t fat_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
 257{
 258	struct file *file = iocb->ki_filp;
 259	struct address_space *mapping = file->f_mapping;
 260	struct inode *inode = mapping->host;
 261	size_t count = iov_iter_count(iter);
 262	loff_t offset = iocb->ki_pos;
 263	ssize_t ret;
 264
 265	if (iov_iter_rw(iter) == WRITE) {
 266		/*
 267		 * FIXME: blockdev_direct_IO() doesn't use ->write_begin(),
 268		 * so we need to update the ->mmu_private to block boundary.
 269		 *
 270		 * But we must fill the remaining area or hole by nul for
 271		 * updating ->mmu_private.
 272		 *
 273		 * Return 0, and fallback to normal buffered write.
 274		 */
 275		loff_t size = offset + count;
 276		if (MSDOS_I(inode)->mmu_private < size)
 277			return 0;
 278	}
 279
 280	/*
 281	 * FAT need to use the DIO_LOCKING for avoiding the race
 282	 * condition of fat_get_block() and ->truncate().
 283	 */
 284	ret = blockdev_direct_IO(iocb, inode, iter, fat_get_block);
 285	if (ret < 0 && iov_iter_rw(iter) == WRITE)
 286		fat_write_failed(mapping, offset + count);
 287
 288	return ret;
 289}
 290
 291static int fat_get_block_bmap(struct inode *inode, sector_t iblock,
 292		struct buffer_head *bh_result, int create)
 293{
 294	struct super_block *sb = inode->i_sb;
 295	unsigned long max_blocks = bh_result->b_size >> inode->i_blkbits;
 296	int err;
 297	sector_t bmap;
 298	unsigned long mapped_blocks;
 299
 300	BUG_ON(create != 0);
 301
 302	err = fat_bmap(inode, iblock, &bmap, &mapped_blocks, create, true);
 303	if (err)
 304		return err;
 305
 306	if (bmap) {
 307		map_bh(bh_result, sb, bmap);
 308		max_blocks = min(mapped_blocks, max_blocks);
 309	}
 310
 311	bh_result->b_size = max_blocks << sb->s_blocksize_bits;
 312
 313	return 0;
 314}
 315
 316static sector_t _fat_bmap(struct address_space *mapping, sector_t block)
 317{
 318	sector_t blocknr;
 319
 320	/* fat_get_cluster() assumes the requested blocknr isn't truncated. */
 321	down_read(&MSDOS_I(mapping->host)->truncate_lock);
 322	blocknr = generic_block_bmap(mapping, block, fat_get_block_bmap);
 323	up_read(&MSDOS_I(mapping->host)->truncate_lock);
 324
 325	return blocknr;
 326}
 327
 328/*
 329 * fat_block_truncate_page() zeroes out a mapping from file offset `from'
 330 * up to the end of the block which corresponds to `from'.
 331 * This is required during truncate to physically zeroout the tail end
 332 * of that block so it doesn't yield old data if the file is later grown.
 333 * Also, avoid causing failure from fsx for cases of "data past EOF"
 334 */
 335int fat_block_truncate_page(struct inode *inode, loff_t from)
 336{
 337	return block_truncate_page(inode->i_mapping, from, fat_get_block);
 338}
 339
 340static const struct address_space_operations fat_aops = {
 341	.dirty_folio	= block_dirty_folio,
 342	.invalidate_folio = block_invalidate_folio,
 343	.read_folio	= fat_read_folio,
 344	.readahead	= fat_readahead,
 345	.writepages	= fat_writepages,
 346	.write_begin	= fat_write_begin,
 347	.write_end	= fat_write_end,
 348	.direct_IO	= fat_direct_IO,
 349	.bmap		= _fat_bmap,
 350	.migrate_folio	= buffer_migrate_folio,
 351};
 352
 353/*
 354 * New FAT inode stuff. We do the following:
 355 *	a) i_ino is constant and has nothing with on-disk location.
 356 *	b) FAT manages its own cache of directory entries.
 357 *	c) *This* cache is indexed by on-disk location.
 358 *	d) inode has an associated directory entry, all right, but
 359 *		it may be unhashed.
 360 *	e) currently entries are stored within struct inode. That should
 361 *		change.
 362 *	f) we deal with races in the following way:
 363 *		1. readdir() and lookup() do FAT-dir-cache lookup.
 364 *		2. rename() unhashes the F-d-c entry and rehashes it in
 365 *			a new place.
 366 *		3. unlink() and rmdir() unhash F-d-c entry.
 367 *		4. fat_write_inode() checks whether the thing is unhashed.
 368 *			If it is we silently return. If it isn't we do bread(),
 369 *			check if the location is still valid and retry if it
 370 *			isn't. Otherwise we do changes.
 371 *		5. Spinlock is used to protect hash/unhash/location check/lookup
 372 *		6. fat_evict_inode() unhashes the F-d-c entry.
 373 *		7. lookup() and readdir() do igrab() if they find a F-d-c entry
 374 *			and consider negative result as cache miss.
 375 */
 376
 377static void fat_hash_init(struct super_block *sb)
 378{
 379	struct msdos_sb_info *sbi = MSDOS_SB(sb);
 380	int i;
 381
 382	spin_lock_init(&sbi->inode_hash_lock);
 383	for (i = 0; i < FAT_HASH_SIZE; i++)
 384		INIT_HLIST_HEAD(&sbi->inode_hashtable[i]);
 385}
 386
 387static inline unsigned long fat_hash(loff_t i_pos)
 388{
 389	return hash_32(i_pos, FAT_HASH_BITS);
 390}
 391
 392static void dir_hash_init(struct super_block *sb)
 393{
 394	struct msdos_sb_info *sbi = MSDOS_SB(sb);
 395	int i;
 396
 397	spin_lock_init(&sbi->dir_hash_lock);
 398	for (i = 0; i < FAT_HASH_SIZE; i++)
 399		INIT_HLIST_HEAD(&sbi->dir_hashtable[i]);
 400}
 401
 402void fat_attach(struct inode *inode, loff_t i_pos)
 403{
 404	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 405
 406	if (inode->i_ino != MSDOS_ROOT_INO) {
 407		struct hlist_head *head =   sbi->inode_hashtable
 408					  + fat_hash(i_pos);
 409
 410		spin_lock(&sbi->inode_hash_lock);
 411		MSDOS_I(inode)->i_pos = i_pos;
 412		hlist_add_head(&MSDOS_I(inode)->i_fat_hash, head);
 413		spin_unlock(&sbi->inode_hash_lock);
 414	}
 415
 416	/* If NFS support is enabled, cache the mapping of start cluster
 417	 * to directory inode. This is used during reconnection of
 418	 * dentries to the filesystem root.
 419	 */
 420	if (S_ISDIR(inode->i_mode) && sbi->options.nfs) {
 421		struct hlist_head *d_head = sbi->dir_hashtable;
 422		d_head += fat_dir_hash(MSDOS_I(inode)->i_logstart);
 423
 424		spin_lock(&sbi->dir_hash_lock);
 425		hlist_add_head(&MSDOS_I(inode)->i_dir_hash, d_head);
 426		spin_unlock(&sbi->dir_hash_lock);
 427	}
 428}
 429EXPORT_SYMBOL_GPL(fat_attach);
 430
 431void fat_detach(struct inode *inode)
 432{
 433	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 434	spin_lock(&sbi->inode_hash_lock);
 435	MSDOS_I(inode)->i_pos = 0;
 436	hlist_del_init(&MSDOS_I(inode)->i_fat_hash);
 437	spin_unlock(&sbi->inode_hash_lock);
 438
 439	if (S_ISDIR(inode->i_mode) && sbi->options.nfs) {
 440		spin_lock(&sbi->dir_hash_lock);
 441		hlist_del_init(&MSDOS_I(inode)->i_dir_hash);
 442		spin_unlock(&sbi->dir_hash_lock);
 443	}
 444}
 445EXPORT_SYMBOL_GPL(fat_detach);
 446
 447struct inode *fat_iget(struct super_block *sb, loff_t i_pos)
 448{
 449	struct msdos_sb_info *sbi = MSDOS_SB(sb);
 450	struct hlist_head *head = sbi->inode_hashtable + fat_hash(i_pos);
 451	struct msdos_inode_info *i;
 452	struct inode *inode = NULL;
 453
 454	spin_lock(&sbi->inode_hash_lock);
 455	hlist_for_each_entry(i, head, i_fat_hash) {
 456		BUG_ON(i->vfs_inode.i_sb != sb);
 457		if (i->i_pos != i_pos)
 458			continue;
 459		inode = igrab(&i->vfs_inode);
 460		if (inode)
 461			break;
 462	}
 463	spin_unlock(&sbi->inode_hash_lock);
 464	return inode;
 465}
 466
 467static int is_exec(unsigned char *extension)
 468{
 469	unsigned char exe_extensions[] = "EXECOMBAT", *walk;
 470
 471	for (walk = exe_extensions; *walk; walk += 3)
 472		if (!strncmp(extension, walk, 3))
 473			return 1;
 474	return 0;
 475}
 476
 477static int fat_calc_dir_size(struct inode *inode)
 478{
 479	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 480	int ret, fclus, dclus;
 481
 482	inode->i_size = 0;
 483	if (MSDOS_I(inode)->i_start == 0)
 484		return 0;
 485
 486	ret = fat_get_cluster(inode, FAT_ENT_EOF, &fclus, &dclus);
 487	if (ret < 0)
 488		return ret;
 489	inode->i_size = (fclus + 1) << sbi->cluster_bits;
 490
 491	return 0;
 492}
 493
 494static int fat_validate_dir(struct inode *dir)
 495{
 496	struct super_block *sb = dir->i_sb;
 497
 498	if (dir->i_nlink < 2) {
 499		/* Directory should have "."/".." entries at least. */
 500		fat_fs_error(sb, "corrupted directory (invalid entries)");
 501		return -EIO;
 502	}
 503	if (MSDOS_I(dir)->i_start == 0 ||
 504	    MSDOS_I(dir)->i_start == MSDOS_SB(sb)->root_cluster) {
 505		/* Directory should point valid cluster. */
 506		fat_fs_error(sb, "corrupted directory (invalid i_start)");
 507		return -EIO;
 508	}
 509	return 0;
 510}
 511
 512/* doesn't deal with root inode */
 513int fat_fill_inode(struct inode *inode, struct msdos_dir_entry *de)
 514{
 515	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 516	struct timespec64 mtime;
 517	int error;
 518
 519	MSDOS_I(inode)->i_pos = 0;
 520	inode->i_uid = sbi->options.fs_uid;
 521	inode->i_gid = sbi->options.fs_gid;
 522	inode_inc_iversion(inode);
 523	inode->i_generation = get_random_u32();
 524
 525	if ((de->attr & ATTR_DIR) && !IS_FREE(de->name)) {
 526		inode->i_generation &= ~1;
 527		inode->i_mode = fat_make_mode(sbi, de->attr, S_IRWXUGO);
 528		inode->i_op = sbi->dir_ops;
 529		inode->i_fop = &fat_dir_operations;
 530
 531		MSDOS_I(inode)->i_start = fat_get_start(sbi, de);
 532		MSDOS_I(inode)->i_logstart = MSDOS_I(inode)->i_start;
 533		error = fat_calc_dir_size(inode);
 534		if (error < 0)
 535			return error;
 536		MSDOS_I(inode)->mmu_private = inode->i_size;
 537
 538		set_nlink(inode, fat_subdirs(inode));
 539
 540		error = fat_validate_dir(inode);
 541		if (error < 0)
 542			return error;
 543	} else { /* not a directory */
 544		inode->i_generation |= 1;
 545		inode->i_mode = fat_make_mode(sbi, de->attr,
 546			((sbi->options.showexec && !is_exec(de->name + 8))
 547			 ? S_IRUGO|S_IWUGO : S_IRWXUGO));
 548		MSDOS_I(inode)->i_start = fat_get_start(sbi, de);
 549
 550		MSDOS_I(inode)->i_logstart = MSDOS_I(inode)->i_start;
 551		inode->i_size = le32_to_cpu(de->size);
 552		inode->i_op = &fat_file_inode_operations;
 553		inode->i_fop = &fat_file_operations;
 554		inode->i_mapping->a_ops = &fat_aops;
 555		MSDOS_I(inode)->mmu_private = inode->i_size;
 556	}
 557	if (de->attr & ATTR_SYS) {
 558		if (sbi->options.sys_immutable)
 559			inode->i_flags |= S_IMMUTABLE;
 560	}
 561	fat_save_attrs(inode, de->attr);
 562
 563	inode->i_blocks = ((inode->i_size + (sbi->cluster_size - 1))
 564			   & ~((loff_t)sbi->cluster_size - 1)) >> 9;
 565
 566	fat_time_fat2unix(sbi, &mtime, de->time, de->date, 0);
 567	inode_set_mtime_to_ts(inode, mtime);
 568	inode_set_ctime_to_ts(inode, mtime);
 569	if (sbi->options.isvfat) {
 570		struct timespec64 atime;
 571
 572		fat_time_fat2unix(sbi, &atime, 0, de->adate, 0);
 573		inode_set_atime_to_ts(inode, atime);
 574		fat_time_fat2unix(sbi, &MSDOS_I(inode)->i_crtime, de->ctime,
 575				  de->cdate, de->ctime_cs);
 576	} else
 577		inode_set_atime_to_ts(inode, fat_truncate_atime(sbi, &mtime));
 578
 579	return 0;
 580}
 581
 582static inline void fat_lock_build_inode(struct msdos_sb_info *sbi)
 583{
 584	if (sbi->options.nfs == FAT_NFS_NOSTALE_RO)
 585		mutex_lock(&sbi->nfs_build_inode_lock);
 586}
 587
 588static inline void fat_unlock_build_inode(struct msdos_sb_info *sbi)
 589{
 590	if (sbi->options.nfs == FAT_NFS_NOSTALE_RO)
 591		mutex_unlock(&sbi->nfs_build_inode_lock);
 592}
 593
 594struct inode *fat_build_inode(struct super_block *sb,
 595			struct msdos_dir_entry *de, loff_t i_pos)
 596{
 597	struct inode *inode;
 598	int err;
 599
 600	fat_lock_build_inode(MSDOS_SB(sb));
 601	inode = fat_iget(sb, i_pos);
 602	if (inode)
 603		goto out;
 604	inode = new_inode(sb);
 605	if (!inode) {
 606		inode = ERR_PTR(-ENOMEM);
 607		goto out;
 608	}
 609	inode->i_ino = iunique(sb, MSDOS_ROOT_INO);
 610	inode_set_iversion(inode, 1);
 611	err = fat_fill_inode(inode, de);
 612	if (err) {
 613		iput(inode);
 614		inode = ERR_PTR(err);
 615		goto out;
 616	}
 617	fat_attach(inode, i_pos);
 618	insert_inode_hash(inode);
 619out:
 620	fat_unlock_build_inode(MSDOS_SB(sb));
 621	return inode;
 622}
 623
 624EXPORT_SYMBOL_GPL(fat_build_inode);
 625
 626static int __fat_write_inode(struct inode *inode, int wait);
 627
 628static void fat_free_eofblocks(struct inode *inode)
 629{
 630	/* Release unwritten fallocated blocks on inode eviction. */
 631	if ((inode->i_blocks << 9) >
 632			round_up(MSDOS_I(inode)->mmu_private,
 633				MSDOS_SB(inode->i_sb)->cluster_size)) {
 634		int err;
 635
 636		fat_truncate_blocks(inode, MSDOS_I(inode)->mmu_private);
 637		/* Fallocate results in updating the i_start/iogstart
 638		 * for the zero byte file. So, make it return to
 639		 * original state during evict and commit it to avoid
 640		 * any corruption on the next access to the cluster
 641		 * chain for the file.
 642		 */
 643		err = __fat_write_inode(inode, inode_needs_sync(inode));
 644		if (err) {
 645			fat_msg(inode->i_sb, KERN_WARNING, "Failed to "
 646					"update on disk inode for unused "
 647					"fallocated blocks, inode could be "
 648					"corrupted. Please run fsck");
 649		}
 650
 651	}
 652}
 653
 654static void fat_evict_inode(struct inode *inode)
 655{
 656	truncate_inode_pages_final(&inode->i_data);
 657	if (!inode->i_nlink) {
 658		inode->i_size = 0;
 659		fat_truncate_blocks(inode, 0);
 660	} else
 661		fat_free_eofblocks(inode);
 662
 663	invalidate_inode_buffers(inode);
 664	clear_inode(inode);
 665	fat_cache_inval_inode(inode);
 666	fat_detach(inode);
 667}
 668
 669static void fat_set_state(struct super_block *sb,
 670			unsigned int set, unsigned int force)
 671{
 672	struct buffer_head *bh;
 673	struct fat_boot_sector *b;
 674	struct msdos_sb_info *sbi = MSDOS_SB(sb);
 675
 676	/* do not change any thing if mounted read only */
 677	if (sb_rdonly(sb) && !force)
 678		return;
 679
 680	/* do not change state if fs was dirty */
 681	if (sbi->dirty) {
 682		/* warn only on set (mount). */
 683		if (set)
 684			fat_msg(sb, KERN_WARNING, "Volume was not properly "
 685				"unmounted. Some data may be corrupt. "
 686				"Please run fsck.");
 687		return;
 688	}
 689
 690	bh = sb_bread(sb, 0);
 691	if (bh == NULL) {
 692		fat_msg(sb, KERN_ERR, "unable to read boot sector "
 693			"to mark fs as dirty");
 694		return;
 695	}
 696
 697	b = (struct fat_boot_sector *) bh->b_data;
 698
 699	if (is_fat32(sbi)) {
 700		if (set)
 701			b->fat32.state |= FAT_STATE_DIRTY;
 702		else
 703			b->fat32.state &= ~FAT_STATE_DIRTY;
 704	} else /* fat 16 and 12 */ {
 705		if (set)
 706			b->fat16.state |= FAT_STATE_DIRTY;
 707		else
 708			b->fat16.state &= ~FAT_STATE_DIRTY;
 709	}
 710
 711	mark_buffer_dirty(bh);
 712	sync_dirty_buffer(bh);
 713	brelse(bh);
 714}
 715
 716static void fat_reset_iocharset(struct fat_mount_options *opts)
 717{
 718	if (opts->iocharset != fat_default_iocharset) {
 719		/* Note: opts->iocharset can be NULL here */
 720		kfree(opts->iocharset);
 721		opts->iocharset = fat_default_iocharset;
 722	}
 723}
 724
 725static void delayed_free(struct rcu_head *p)
 726{
 727	struct msdos_sb_info *sbi = container_of(p, struct msdos_sb_info, rcu);
 728	unload_nls(sbi->nls_disk);
 729	unload_nls(sbi->nls_io);
 730	fat_reset_iocharset(&sbi->options);
 731	kfree(sbi);
 732}
 733
 734static void fat_put_super(struct super_block *sb)
 735{
 736	struct msdos_sb_info *sbi = MSDOS_SB(sb);
 737
 738	fat_set_state(sb, 0, 0);
 739
 740	iput(sbi->fsinfo_inode);
 741	iput(sbi->fat_inode);
 742
 743	call_rcu(&sbi->rcu, delayed_free);
 744}
 745
 746static struct kmem_cache *fat_inode_cachep;
 747
 748static struct inode *fat_alloc_inode(struct super_block *sb)
 749{
 750	struct msdos_inode_info *ei;
 751	ei = alloc_inode_sb(sb, fat_inode_cachep, GFP_NOFS);
 752	if (!ei)
 753		return NULL;
 754
 755	init_rwsem(&ei->truncate_lock);
 756	/* Zeroing to allow iput() even if partial initialized inode. */
 757	ei->mmu_private = 0;
 758	ei->i_start = 0;
 759	ei->i_logstart = 0;
 760	ei->i_attrs = 0;
 761	ei->i_pos = 0;
 762	ei->i_crtime.tv_sec = 0;
 763	ei->i_crtime.tv_nsec = 0;
 764
 765	return &ei->vfs_inode;
 766}
 767
 768static void fat_free_inode(struct inode *inode)
 769{
 770	kmem_cache_free(fat_inode_cachep, MSDOS_I(inode));
 771}
 772
 773static void init_once(void *foo)
 774{
 775	struct msdos_inode_info *ei = (struct msdos_inode_info *)foo;
 776
 777	spin_lock_init(&ei->cache_lru_lock);
 778	ei->nr_caches = 0;
 779	ei->cache_valid_id = FAT_CACHE_VALID + 1;
 780	INIT_LIST_HEAD(&ei->cache_lru);
 781	INIT_HLIST_NODE(&ei->i_fat_hash);
 782	INIT_HLIST_NODE(&ei->i_dir_hash);
 783	inode_init_once(&ei->vfs_inode);
 784}
 785
 786static int __init fat_init_inodecache(void)
 787{
 788	fat_inode_cachep = kmem_cache_create("fat_inode_cache",
 789					     sizeof(struct msdos_inode_info),
 790					     0, (SLAB_RECLAIM_ACCOUNT|
 791						SLAB_ACCOUNT),
 792					     init_once);
 793	if (fat_inode_cachep == NULL)
 794		return -ENOMEM;
 795	return 0;
 796}
 797
 798static void __exit fat_destroy_inodecache(void)
 799{
 800	/*
 801	 * Make sure all delayed rcu free inodes are flushed before we
 802	 * destroy cache.
 803	 */
 804	rcu_barrier();
 805	kmem_cache_destroy(fat_inode_cachep);
 806}
 807
 808int fat_reconfigure(struct fs_context *fc)
 809{
 810	bool new_rdonly;
 811	struct super_block *sb = fc->root->d_sb;
 812	struct msdos_sb_info *sbi = MSDOS_SB(sb);
 813	fc->sb_flags |= SB_NODIRATIME | (sbi->options.isvfat ? 0 : SB_NOATIME);
 814
 815	sync_filesystem(sb);
 816
 817	/* make sure we update state on remount. */
 818	new_rdonly = fc->sb_flags & SB_RDONLY;
 819	if (new_rdonly != sb_rdonly(sb)) {
 820		if (new_rdonly)
 821			fat_set_state(sb, 0, 0);
 822		else
 823			fat_set_state(sb, 1, 1);
 824	}
 825	return 0;
 826}
 827EXPORT_SYMBOL_GPL(fat_reconfigure);
 828
 829static int fat_statfs(struct dentry *dentry, struct kstatfs *buf)
 830{
 831	struct super_block *sb = dentry->d_sb;
 832	struct msdos_sb_info *sbi = MSDOS_SB(sb);
 833	u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
 834
 835	/* If the count of free cluster is still unknown, counts it here. */
 836	if (sbi->free_clusters == -1 || !sbi->free_clus_valid) {
 837		int err = fat_count_free_clusters(dentry->d_sb);
 838		if (err)
 839			return err;
 840	}
 841
 842	buf->f_type = dentry->d_sb->s_magic;
 843	buf->f_bsize = sbi->cluster_size;
 844	buf->f_blocks = sbi->max_cluster - FAT_START_ENT;
 845	buf->f_bfree = sbi->free_clusters;
 846	buf->f_bavail = sbi->free_clusters;
 847	buf->f_fsid = u64_to_fsid(id);
 848	buf->f_namelen =
 849		(sbi->options.isvfat ? FAT_LFN_LEN : 12) * NLS_MAX_CHARSET_SIZE;
 850
 851	return 0;
 852}
 853
 854static int __fat_write_inode(struct inode *inode, int wait)
 855{
 856	struct super_block *sb = inode->i_sb;
 857	struct msdos_sb_info *sbi = MSDOS_SB(sb);
 858	struct buffer_head *bh;
 859	struct msdos_dir_entry *raw_entry;
 860	struct timespec64 mtime;
 861	loff_t i_pos;
 862	sector_t blocknr;
 863	int err, offset;
 864
 865	if (inode->i_ino == MSDOS_ROOT_INO)
 866		return 0;
 867
 868retry:
 869	i_pos = fat_i_pos_read(sbi, inode);
 870	if (!i_pos)
 871		return 0;
 872
 873	fat_get_blknr_offset(sbi, i_pos, &blocknr, &offset);
 874	bh = sb_bread(sb, blocknr);
 875	if (!bh) {
 876		fat_msg(sb, KERN_ERR, "unable to read inode block "
 877		       "for updating (i_pos %lld)", i_pos);
 878		return -EIO;
 879	}
 880	spin_lock(&sbi->inode_hash_lock);
 881	if (i_pos != MSDOS_I(inode)->i_pos) {
 882		spin_unlock(&sbi->inode_hash_lock);
 883		brelse(bh);
 884		goto retry;
 885	}
 886
 887	raw_entry = &((struct msdos_dir_entry *) (bh->b_data))[offset];
 888	if (S_ISDIR(inode->i_mode))
 889		raw_entry->size = 0;
 890	else
 891		raw_entry->size = cpu_to_le32(inode->i_size);
 892	raw_entry->attr = fat_make_attrs(inode);
 893	fat_set_start(raw_entry, MSDOS_I(inode)->i_logstart);
 894	mtime = inode_get_mtime(inode);
 895	fat_time_unix2fat(sbi, &mtime, &raw_entry->time,
 896			  &raw_entry->date, NULL);
 897	if (sbi->options.isvfat) {
 898		struct timespec64 ts = inode_get_atime(inode);
 899		__le16 atime;
 900
 901		fat_time_unix2fat(sbi, &ts, &atime, &raw_entry->adate, NULL);
 902		fat_time_unix2fat(sbi, &MSDOS_I(inode)->i_crtime, &raw_entry->ctime,
 903				  &raw_entry->cdate, &raw_entry->ctime_cs);
 904	}
 905	spin_unlock(&sbi->inode_hash_lock);
 906	mark_buffer_dirty(bh);
 907	err = 0;
 908	if (wait)
 909		err = sync_dirty_buffer(bh);
 910	brelse(bh);
 911	return err;
 912}
 913
 914static int fat_write_inode(struct inode *inode, struct writeback_control *wbc)
 915{
 916	int err;
 917
 918	if (inode->i_ino == MSDOS_FSINFO_INO) {
 919		struct super_block *sb = inode->i_sb;
 920
 921		mutex_lock(&MSDOS_SB(sb)->s_lock);
 922		err = fat_clusters_flush(sb);
 923		mutex_unlock(&MSDOS_SB(sb)->s_lock);
 924	} else
 925		err = __fat_write_inode(inode, wbc->sync_mode == WB_SYNC_ALL);
 926
 927	return err;
 928}
 929
 930int fat_sync_inode(struct inode *inode)
 931{
 932	return __fat_write_inode(inode, 1);
 933}
 934
 935EXPORT_SYMBOL_GPL(fat_sync_inode);
 936
 937static int fat_show_options(struct seq_file *m, struct dentry *root);
 938static const struct super_operations fat_sops = {
 939	.alloc_inode	= fat_alloc_inode,
 940	.free_inode	= fat_free_inode,
 941	.write_inode	= fat_write_inode,
 942	.evict_inode	= fat_evict_inode,
 943	.put_super	= fat_put_super,
 944	.statfs		= fat_statfs,
 945	.show_options	= fat_show_options,
 946};
 947
 948static int fat_show_options(struct seq_file *m, struct dentry *root)
 949{
 950	struct msdos_sb_info *sbi = MSDOS_SB(root->d_sb);
 951	struct fat_mount_options *opts = &sbi->options;
 952	int isvfat = opts->isvfat;
 953
 954	if (!uid_eq(opts->fs_uid, GLOBAL_ROOT_UID))
 955		seq_printf(m, ",uid=%u",
 956				from_kuid_munged(&init_user_ns, opts->fs_uid));
 957	if (!gid_eq(opts->fs_gid, GLOBAL_ROOT_GID))
 958		seq_printf(m, ",gid=%u",
 959				from_kgid_munged(&init_user_ns, opts->fs_gid));
 960	seq_printf(m, ",fmask=%04o", opts->fs_fmask);
 961	seq_printf(m, ",dmask=%04o", opts->fs_dmask);
 962	if (opts->allow_utime)
 963		seq_printf(m, ",allow_utime=%04o", opts->allow_utime);
 964	if (sbi->nls_disk)
 965		/* strip "cp" prefix from displayed option */
 966		seq_printf(m, ",codepage=%s", &sbi->nls_disk->charset[2]);
 967	if (isvfat) {
 968		if (sbi->nls_io)
 969			seq_printf(m, ",iocharset=%s", sbi->nls_io->charset);
 970
 971		switch (opts->shortname) {
 972		case VFAT_SFN_DISPLAY_WIN95 | VFAT_SFN_CREATE_WIN95:
 973			seq_puts(m, ",shortname=win95");
 974			break;
 975		case VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WINNT:
 976			seq_puts(m, ",shortname=winnt");
 977			break;
 978		case VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WIN95:
 979			seq_puts(m, ",shortname=mixed");
 980			break;
 981		case VFAT_SFN_DISPLAY_LOWER | VFAT_SFN_CREATE_WIN95:
 982			seq_puts(m, ",shortname=lower");
 983			break;
 984		default:
 985			seq_puts(m, ",shortname=unknown");
 986			break;
 987		}
 988	}
 989	if (opts->name_check != 'n')
 990		seq_printf(m, ",check=%c", opts->name_check);
 991	if (opts->usefree)
 992		seq_puts(m, ",usefree");
 993	if (opts->quiet)
 994		seq_puts(m, ",quiet");
 995	if (opts->showexec)
 996		seq_puts(m, ",showexec");
 997	if (opts->sys_immutable)
 998		seq_puts(m, ",sys_immutable");
 999	if (!isvfat) {
1000		if (opts->dotsOK)
1001			seq_puts(m, ",dotsOK=yes");
1002		if (opts->nocase)
1003			seq_puts(m, ",nocase");
1004	} else {
1005		if (opts->utf8)
1006			seq_puts(m, ",utf8");
1007		if (opts->unicode_xlate)
1008			seq_puts(m, ",uni_xlate");
1009		if (!opts->numtail)
1010			seq_puts(m, ",nonumtail");
1011		if (opts->rodir)
1012			seq_puts(m, ",rodir");
1013	}
1014	if (opts->flush)
1015		seq_puts(m, ",flush");
1016	if (opts->tz_set) {
1017		if (opts->time_offset)
1018			seq_printf(m, ",time_offset=%d", opts->time_offset);
1019		else
1020			seq_puts(m, ",tz=UTC");
1021	}
1022	if (opts->errors == FAT_ERRORS_CONT)
1023		seq_puts(m, ",errors=continue");
1024	else if (opts->errors == FAT_ERRORS_PANIC)
1025		seq_puts(m, ",errors=panic");
1026	else
1027		seq_puts(m, ",errors=remount-ro");
1028	if (opts->nfs == FAT_NFS_NOSTALE_RO)
1029		seq_puts(m, ",nfs=nostale_ro");
1030	else if (opts->nfs)
1031		seq_puts(m, ",nfs=stale_rw");
1032	if (opts->discard)
1033		seq_puts(m, ",discard");
1034	if (opts->dos1xfloppy)
1035		seq_puts(m, ",dos1xfloppy");
1036
1037	return 0;
1038}
1039
1040enum {
1041	Opt_check, Opt_uid, Opt_gid, Opt_umask, Opt_dmask, Opt_fmask,
1042	Opt_allow_utime, Opt_codepage, Opt_usefree, Opt_nocase, Opt_quiet,
1043	Opt_showexec, Opt_debug, Opt_immutable, Opt_dots, Opt_dotsOK,
1044	Opt_charset, Opt_shortname, Opt_utf8, Opt_utf8_bool,
1045	Opt_uni_xl, Opt_uni_xl_bool, Opt_nonumtail, Opt_nonumtail_bool,
1046	Opt_obsolete, Opt_flush, Opt_tz, Opt_rodir, Opt_errors, Opt_discard,
1047	Opt_nfs, Opt_nfs_enum, Opt_time_offset, Opt_dos1xfloppy,
1048};
1049
1050static const struct constant_table fat_param_check[] = {
1051	{"relaxed",	'r'},
1052	{"r",		'r'},
1053	{"strict",	's'},
1054	{"s",		's'},
1055	{"normal",	'n'},
1056	{"n",		'n'},
1057	{}
1058};
1059
1060static const struct constant_table fat_param_tz[] = {
1061	{"UTC",		0},
1062	{}
1063};
1064
1065static const struct constant_table fat_param_errors[] = {
1066	{"continue",	FAT_ERRORS_CONT},
1067	{"panic",	FAT_ERRORS_PANIC},
1068	{"remount-ro",	FAT_ERRORS_RO},
1069	{}
1070};
1071
1072
1073static const struct constant_table fat_param_nfs[] = {
1074	{"stale_rw",	FAT_NFS_STALE_RW},
1075	{"nostale_ro",	FAT_NFS_NOSTALE_RO},
1076	{}
1077};
1078
1079/*
1080 * These are all obsolete but we still reject invalid options.
1081 * The corresponding values are therefore meaningless.
1082 */
1083static const struct constant_table fat_param_conv[] = {
1084	{"binary",	0},
1085	{"text",	0},
1086	{"auto",	0},
1087	{"b",		0},
1088	{"t",		0},
1089	{"a",		0},
1090	{}
1091};
1092
1093/* Core options. See below for vfat and msdos extras */
1094const struct fs_parameter_spec fat_param_spec[] = {
1095	fsparam_enum	("check",	Opt_check, fat_param_check),
1096	fsparam_uid	("uid",		Opt_uid),
1097	fsparam_gid	("gid",		Opt_gid),
1098	fsparam_u32oct	("umask",	Opt_umask),
1099	fsparam_u32oct	("dmask",	Opt_dmask),
1100	fsparam_u32oct	("fmask",	Opt_fmask),
1101	fsparam_u32oct	("allow_utime",	Opt_allow_utime),
1102	fsparam_u32	("codepage",	Opt_codepage),
1103	fsparam_flag	("usefree",	Opt_usefree),
1104	fsparam_flag	("nocase",	Opt_nocase),
1105	fsparam_flag	("quiet",	Opt_quiet),
1106	fsparam_flag	("showexec",	Opt_showexec),
1107	fsparam_flag	("debug",	Opt_debug),
1108	fsparam_flag	("sys_immutable", Opt_immutable),
1109	fsparam_flag	("flush",	Opt_flush),
1110	fsparam_enum	("tz",		Opt_tz, fat_param_tz),
1111	fsparam_s32	("time_offset",	Opt_time_offset),
1112	fsparam_enum	("errors",	Opt_errors, fat_param_errors),
1113	fsparam_flag	("discard",	Opt_discard),
1114	fsparam_flag	("nfs",		Opt_nfs),
1115	fsparam_enum	("nfs",		Opt_nfs_enum, fat_param_nfs),
1116	fsparam_flag	("dos1xfloppy",	Opt_dos1xfloppy),
1117	__fsparam(fs_param_is_enum,	"conv",
1118		  Opt_obsolete, fs_param_deprecated, fat_param_conv),
1119	__fsparam(fs_param_is_u32,	"fat",
1120		  Opt_obsolete, fs_param_deprecated, NULL),
1121	__fsparam(fs_param_is_u32,	"blocksize",
1122		  Opt_obsolete, fs_param_deprecated, NULL),
1123	__fsparam(fs_param_is_string,	"cvf_format",
1124		  Opt_obsolete, fs_param_deprecated, NULL),
1125	__fsparam(fs_param_is_string,	"cvf_options",
1126		  Opt_obsolete, fs_param_deprecated, NULL),
1127	__fsparam(NULL,			"posix",
1128		  Opt_obsolete, fs_param_deprecated, NULL),
1129	{}
1130};
1131EXPORT_SYMBOL_GPL(fat_param_spec);
1132
1133static const struct fs_parameter_spec msdos_param_spec[] = {
1134	fsparam_flag_no	("dots",	Opt_dots),
1135	fsparam_bool	("dotsOK",	Opt_dotsOK),
1136	{}
1137};
1138
1139static const struct constant_table fat_param_shortname[] = {
1140	{"lower",	VFAT_SFN_DISPLAY_LOWER | VFAT_SFN_CREATE_WIN95},
1141	{"win95",	VFAT_SFN_DISPLAY_WIN95 | VFAT_SFN_CREATE_WIN95},
1142	{"winnt",	VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WINNT},
1143	{"mixed",	VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WIN95},
1144	{}
1145};
1146
1147static const struct fs_parameter_spec vfat_param_spec[] = {
1148	fsparam_string	("iocharset",	Opt_charset),
1149	fsparam_enum	("shortname",	Opt_shortname, fat_param_shortname),
1150	fsparam_flag	("utf8",	Opt_utf8),
1151	fsparam_bool	("utf8",	Opt_utf8_bool),
1152	fsparam_flag	("uni_xlate",	Opt_uni_xl),
1153	fsparam_bool	("uni_xlate",	Opt_uni_xl_bool),
1154	fsparam_flag	("nonumtail",	Opt_nonumtail),
1155	fsparam_bool	("nonumtail",	Opt_nonumtail_bool),
1156	fsparam_flag	("rodir",	Opt_rodir),
1157	{}
1158};
1159
1160int fat_parse_param(struct fs_context *fc, struct fs_parameter *param,
1161			   bool is_vfat)
1162{
1163	struct fat_mount_options *opts = fc->fs_private;
1164	struct fs_parse_result result;
1165	int opt;
1166
1167	/* remount options have traditionally been ignored */
1168	if (fc->purpose == FS_CONTEXT_FOR_RECONFIGURE)
1169		return 0;
1170
1171	opt = fs_parse(fc, fat_param_spec, param, &result);
1172	/* If option not found in fat_param_spec, try vfat/msdos options */
1173	if (opt == -ENOPARAM) {
1174		if (is_vfat)
1175			opt = fs_parse(fc, vfat_param_spec, param, &result);
1176		else
1177			opt = fs_parse(fc, msdos_param_spec, param, &result);
1178	}
1179
1180	if (opt < 0)
1181		return opt;
1182
1183	switch (opt) {
1184	case Opt_check:
1185		opts->name_check = result.uint_32;
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		opts->debug = 1;
1207		break;
1208	case Opt_immutable:
1209		opts->sys_immutable = 1;
1210		break;
1211	case Opt_uid:
1212		opts->fs_uid = result.uid;
1213		break;
1214	case Opt_gid:
1215		opts->fs_gid = result.gid;
1216		break;
1217	case Opt_umask:
1218		opts->fs_fmask = opts->fs_dmask = result.uint_32;
1219		break;
1220	case Opt_dmask:
1221		opts->fs_dmask = result.uint_32;
1222		break;
1223	case Opt_fmask:
1224		opts->fs_fmask = result.uint_32;
1225		break;
1226	case Opt_allow_utime:
1227		opts->allow_utime = result.uint_32 & (S_IWGRP | S_IWOTH);
1228		break;
1229	case Opt_codepage:
1230		opts->codepage = result.uint_32;
1231		break;
1232	case Opt_flush:
1233		opts->flush = 1;
1234		break;
1235	case Opt_time_offset:
1236		/*
1237		 * GMT+-12 zones may have DST corrections so at least
1238		 * 13 hours difference is needed. Make the limit 24
1239		 * just in case someone invents something unusual.
1240		 */
1241		if (result.int_32 < -24 * 60 || result.int_32 > 24 * 60)
1242			return -EINVAL;
1243		opts->tz_set = 1;
1244		opts->time_offset = result.int_32;
1245		break;
1246	case Opt_tz:
1247		opts->tz_set = 1;
1248		opts->time_offset = result.uint_32;
1249		break;
1250	case Opt_errors:
1251		opts->errors = result.uint_32;
1252		break;
1253	case Opt_nfs:
1254		opts->nfs = FAT_NFS_STALE_RW;
1255		break;
1256	case Opt_nfs_enum:
1257		opts->nfs = result.uint_32;
1258		break;
1259	case Opt_dos1xfloppy:
1260		opts->dos1xfloppy = 1;
1261		break;
1262
1263	/* msdos specific */
1264	case Opt_dots:	/* dots / nodots */
1265		opts->dotsOK = !result.negated;
1266		break;
1267	case Opt_dotsOK:	/* dotsOK = yes/no */
1268		opts->dotsOK = result.boolean;
1269		break;
1270
1271	/* vfat specific */
1272	case Opt_charset:
1273		fat_reset_iocharset(opts);
1274		opts->iocharset = param->string;
1275		param->string = NULL;	/* Steal string */
1276		break;
1277	case Opt_shortname:
1278		opts->shortname = result.uint_32;
1279		break;
1280	case Opt_utf8:
1281		opts->utf8 = 1;
1282		break;
1283	case Opt_utf8_bool:
1284		opts->utf8 = result.boolean;
1285		break;
1286	case Opt_uni_xl:
1287		opts->unicode_xlate = 1;
1288		break;
1289	case Opt_uni_xl_bool:
1290		opts->unicode_xlate = result.boolean;
1291		break;
1292	case Opt_nonumtail:
1293		opts->numtail = 0;	/* negated option */
1294		break;
1295	case Opt_nonumtail_bool:
1296		opts->numtail = !result.boolean; /* negated option */
1297		break;
1298	case Opt_rodir:
1299		opts->rodir = 1;
1300		break;
1301	case Opt_discard:
1302		opts->discard = 1;
1303		break;
1304
1305	/* obsolete mount options */
1306	case Opt_obsolete:
1307		printk(KERN_INFO "FAT-fs: \"%s\" option is obsolete, "
1308			"not supported now", param->key);
1309		break;
1310	default:
1311		return -EINVAL;
1312	}
1313
1314	return 0;
1315}
1316EXPORT_SYMBOL_GPL(fat_parse_param);
1317
1318static int fat_read_root(struct inode *inode)
1319{
1320	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
1321	int error;
1322
1323	MSDOS_I(inode)->i_pos = MSDOS_ROOT_INO;
1324	inode->i_uid = sbi->options.fs_uid;
1325	inode->i_gid = sbi->options.fs_gid;
1326	inode_inc_iversion(inode);
1327	inode->i_generation = 0;
1328	inode->i_mode = fat_make_mode(sbi, ATTR_DIR, S_IRWXUGO);
1329	inode->i_op = sbi->dir_ops;
1330	inode->i_fop = &fat_dir_operations;
1331	if (is_fat32(sbi)) {
1332		MSDOS_I(inode)->i_start = sbi->root_cluster;
1333		error = fat_calc_dir_size(inode);
1334		if (error < 0)
1335			return error;
1336	} else {
1337		MSDOS_I(inode)->i_start = 0;
1338		inode->i_size = sbi->dir_entries * sizeof(struct msdos_dir_entry);
1339	}
1340	inode->i_blocks = ((inode->i_size + (sbi->cluster_size - 1))
1341			   & ~((loff_t)sbi->cluster_size - 1)) >> 9;
1342	MSDOS_I(inode)->i_logstart = 0;
1343	MSDOS_I(inode)->mmu_private = inode->i_size;
1344
1345	fat_save_attrs(inode, ATTR_DIR);
1346	inode_set_mtime_to_ts(inode,
1347			      inode_set_atime_to_ts(inode, inode_set_ctime(inode, 0, 0)));
1348	set_nlink(inode, fat_subdirs(inode)+2);
1349
1350	return 0;
1351}
1352
1353static unsigned long calc_fat_clusters(struct super_block *sb)
1354{
1355	struct msdos_sb_info *sbi = MSDOS_SB(sb);
1356
1357	/* Divide first to avoid overflow */
1358	if (!is_fat12(sbi)) {
1359		unsigned long ent_per_sec = sb->s_blocksize * 8 / sbi->fat_bits;
1360		return ent_per_sec * sbi->fat_length;
1361	}
1362
1363	return sbi->fat_length * sb->s_blocksize * 8 / sbi->fat_bits;
1364}
1365
1366static bool fat_bpb_is_zero(struct fat_boot_sector *b)
1367{
1368	if (get_unaligned_le16(&b->sector_size))
1369		return false;
1370	if (b->sec_per_clus)
1371		return false;
1372	if (b->reserved)
1373		return false;
1374	if (b->fats)
1375		return false;
1376	if (get_unaligned_le16(&b->dir_entries))
1377		return false;
1378	if (get_unaligned_le16(&b->sectors))
1379		return false;
1380	if (b->media)
1381		return false;
1382	if (b->fat_length)
1383		return false;
1384	if (b->secs_track)
1385		return false;
1386	if (b->heads)
1387		return false;
1388	return true;
1389}
1390
1391static int fat_read_bpb(struct super_block *sb, struct fat_boot_sector *b,
1392	int silent, struct fat_bios_param_block *bpb)
1393{
1394	int error = -EINVAL;
1395
1396	/* Read in BPB ... */
1397	memset(bpb, 0, sizeof(*bpb));
1398	bpb->fat_sector_size = get_unaligned_le16(&b->sector_size);
1399	bpb->fat_sec_per_clus = b->sec_per_clus;
1400	bpb->fat_reserved = le16_to_cpu(b->reserved);
1401	bpb->fat_fats = b->fats;
1402	bpb->fat_dir_entries = get_unaligned_le16(&b->dir_entries);
1403	bpb->fat_sectors = get_unaligned_le16(&b->sectors);
1404	bpb->fat_fat_length = le16_to_cpu(b->fat_length);
1405	bpb->fat_total_sect = le32_to_cpu(b->total_sect);
1406
1407	bpb->fat16_state = b->fat16.state;
1408	bpb->fat16_vol_id = get_unaligned_le32(b->fat16.vol_id);
1409
1410	bpb->fat32_length = le32_to_cpu(b->fat32.length);
1411	bpb->fat32_root_cluster = le32_to_cpu(b->fat32.root_cluster);
1412	bpb->fat32_info_sector = le16_to_cpu(b->fat32.info_sector);
1413	bpb->fat32_state = b->fat32.state;
1414	bpb->fat32_vol_id = get_unaligned_le32(b->fat32.vol_id);
1415
1416	/* Validate this looks like a FAT filesystem BPB */
1417	if (!bpb->fat_reserved) {
1418		if (!silent)
1419			fat_msg(sb, KERN_ERR,
1420				"bogus number of reserved sectors");
1421		goto out;
1422	}
1423	if (!bpb->fat_fats) {
1424		if (!silent)
1425			fat_msg(sb, KERN_ERR, "bogus number of FAT structure");
1426		goto out;
1427	}
1428
1429	/*
1430	 * Earlier we checked here that b->secs_track and b->head are nonzero,
1431	 * but it turns out valid FAT filesystems can have zero there.
1432	 */
1433
1434	if (!fat_valid_media(b->media)) {
1435		if (!silent)
1436			fat_msg(sb, KERN_ERR, "invalid media value (0x%02x)",
1437				(unsigned)b->media);
1438		goto out;
1439	}
1440
1441	if (!is_power_of_2(bpb->fat_sector_size)
1442	    || (bpb->fat_sector_size < 512)
1443	    || (bpb->fat_sector_size > 4096)) {
1444		if (!silent)
1445			fat_msg(sb, KERN_ERR, "bogus logical sector size %u",
1446			       (unsigned)bpb->fat_sector_size);
1447		goto out;
1448	}
1449
1450	if (!is_power_of_2(bpb->fat_sec_per_clus)) {
1451		if (!silent)
1452			fat_msg(sb, KERN_ERR, "bogus sectors per cluster %u",
1453				(unsigned)bpb->fat_sec_per_clus);
1454		goto out;
1455	}
1456
1457	if (bpb->fat_fat_length == 0 && bpb->fat32_length == 0) {
1458		if (!silent)
1459			fat_msg(sb, KERN_ERR, "bogus number of FAT sectors");
1460		goto out;
1461	}
1462
1463	error = 0;
1464
1465out:
1466	return error;
1467}
1468
1469static int fat_read_static_bpb(struct super_block *sb,
1470	struct fat_boot_sector *b, int silent,
1471	struct fat_bios_param_block *bpb)
1472{
1473	static const char *notdos1x = "This doesn't look like a DOS 1.x volume";
1474	sector_t bd_sects = bdev_nr_sectors(sb->s_bdev);
1475	struct fat_floppy_defaults *fdefaults = NULL;
1476	int error = -EINVAL;
1477	unsigned i;
1478
1479	/* 16-bit DOS 1.x reliably wrote bootstrap short-jmp code */
1480	if (b->ignored[0] != 0xeb || b->ignored[2] != 0x90) {
1481		if (!silent)
1482			fat_msg(sb, KERN_ERR,
1483				"%s; no bootstrapping code", notdos1x);
1484		goto out;
1485	}
1486
1487	/*
1488	 * If any value in this region is non-zero, it isn't archaic
1489	 * DOS.
1490	 */
1491	if (!fat_bpb_is_zero(b)) {
1492		if (!silent)
1493			fat_msg(sb, KERN_ERR,
1494				"%s; DOS 2.x BPB is non-zero", notdos1x);
1495		goto out;
1496	}
1497
1498	for (i = 0; i < ARRAY_SIZE(floppy_defaults); i++) {
1499		if (floppy_defaults[i].nr_sectors == bd_sects) {
1500			fdefaults = &floppy_defaults[i];
1501			break;
1502		}
1503	}
1504
1505	if (fdefaults == NULL) {
1506		if (!silent)
1507			fat_msg(sb, KERN_WARNING,
1508				"This looks like a DOS 1.x volume, but isn't a recognized floppy size (%llu sectors)",
1509				(u64)bd_sects);
1510		goto out;
1511	}
1512
1513	if (!silent)
1514		fat_msg(sb, KERN_INFO,
1515			"This looks like a DOS 1.x volume; assuming default BPB values");
1516
1517	memset(bpb, 0, sizeof(*bpb));
1518	bpb->fat_sector_size = SECTOR_SIZE;
1519	bpb->fat_sec_per_clus = fdefaults->sec_per_clus;
1520	bpb->fat_reserved = 1;
1521	bpb->fat_fats = 2;
1522	bpb->fat_dir_entries = fdefaults->dir_entries;
1523	bpb->fat_sectors = fdefaults->nr_sectors;
1524	bpb->fat_fat_length = fdefaults->fat_length;
1525
1526	error = 0;
1527
1528out:
1529	return error;
1530}
1531
1532/*
1533 * Read the super block of an MS-DOS FS.
1534 */
1535int fat_fill_super(struct super_block *sb, struct fs_context *fc,
1536		   void (*setup)(struct super_block *))
1537{
1538	struct fat_mount_options *opts = fc->fs_private;
1539	int silent = fc->sb_flags & SB_SILENT;
1540	struct inode *root_inode = NULL, *fat_inode = NULL;
1541	struct inode *fsinfo_inode = NULL;
1542	struct buffer_head *bh;
1543	struct fat_bios_param_block bpb;
1544	struct msdos_sb_info *sbi;
1545	u16 logical_sector_size;
1546	u32 total_sectors, total_clusters, fat_clusters, rootdir_sectors;
1547	long error;
1548	char buf[50];
1549	struct timespec64 ts;
1550
1551	/*
1552	 * GFP_KERNEL is ok here, because while we do hold the
1553	 * superblock lock, memory pressure can't call back into
1554	 * the filesystem, since we're only just about to mount
1555	 * it and have no inodes etc active!
1556	 */
1557	sbi = kzalloc(sizeof(struct msdos_sb_info), GFP_KERNEL);
1558	if (!sbi)
1559		return -ENOMEM;
1560	sb->s_fs_info = sbi;
1561
1562	sb->s_flags |= SB_NODIRATIME;
1563	sb->s_magic = MSDOS_SUPER_MAGIC;
1564	sb->s_op = &fat_sops;
1565	sb->s_export_op = &fat_export_ops;
1566	/*
1567	 * fat timestamps are complex and truncated by fat itself, so
1568	 * we set 1 here to be fast
1569	 */
1570	sb->s_time_gran = 1;
1571	mutex_init(&sbi->nfs_build_inode_lock);
1572	ratelimit_state_init(&sbi->ratelimit, DEFAULT_RATELIMIT_INTERVAL,
1573			     DEFAULT_RATELIMIT_BURST);
1574
1575	/* UTF-8 doesn't provide FAT semantics */
1576	if (!strcmp(opts->iocharset, "utf8")) {
1577		fat_msg(sb, KERN_WARNING, "utf8 is not a recommended IO charset"
1578		       " for FAT filesystems, filesystem will be"
1579		       " case sensitive!");
1580	}
1581
1582	/* If user doesn't specify allow_utime, it's initialized from dmask. */
1583	if (opts->allow_utime == (unsigned short)-1)
1584		opts->allow_utime = ~opts->fs_dmask & (S_IWGRP | S_IWOTH);
1585	if (opts->unicode_xlate)
1586		opts->utf8 = 0;
1587	if (opts->nfs == FAT_NFS_NOSTALE_RO) {
1588		sb->s_flags |= SB_RDONLY;
1589		sb->s_export_op = &fat_export_ops_nostale;
1590	}
1591
1592	/* Apply parsed options to sbi (structure copy) */
1593	sbi->options = *opts;
1594	/* Transfer ownership of iocharset to sbi->options */
1595	opts->iocharset = NULL;
1596
1597	setup(sb); /* flavour-specific stuff that needs options */
1598
1599	error = -EINVAL;
1600	if (!sb_min_blocksize(sb, 512)) {
1601		fat_msg(sb, KERN_ERR, "unable to set blocksize");
1602		goto out_fail;
1603	}
1604	error = -EIO;
1605	bh = sb_bread(sb, 0);
1606	if (bh == NULL) {
1607		fat_msg(sb, KERN_ERR, "unable to read boot sector");
1608		goto out_fail;
1609	}
1610
1611	error = fat_read_bpb(sb, (struct fat_boot_sector *)bh->b_data, silent,
1612		&bpb);
1613	if (error == -EINVAL && sbi->options.dos1xfloppy)
1614		error = fat_read_static_bpb(sb,
1615			(struct fat_boot_sector *)bh->b_data, silent, &bpb);
1616	brelse(bh);
1617
1618	if (error == -EINVAL)
1619		goto out_invalid;
1620	else if (error)
1621		goto out_fail;
1622
1623	logical_sector_size = bpb.fat_sector_size;
1624	sbi->sec_per_clus = bpb.fat_sec_per_clus;
1625
1626	error = -EIO;
1627	if (logical_sector_size < sb->s_blocksize) {
1628		fat_msg(sb, KERN_ERR, "logical sector size too small for device"
1629		       " (logical sector size = %u)", logical_sector_size);
1630		goto out_fail;
1631	}
1632
1633	if (logical_sector_size > sb->s_blocksize) {
1634		struct buffer_head *bh_resize;
1635
1636		if (!sb_set_blocksize(sb, logical_sector_size)) {
1637			fat_msg(sb, KERN_ERR, "unable to set blocksize %u",
1638			       logical_sector_size);
1639			goto out_fail;
1640		}
1641
1642		/* Verify that the larger boot sector is fully readable */
1643		bh_resize = sb_bread(sb, 0);
1644		if (bh_resize == NULL) {
1645			fat_msg(sb, KERN_ERR, "unable to read boot sector"
1646			       " (logical sector size = %lu)",
1647			       sb->s_blocksize);
1648			goto out_fail;
1649		}
1650		brelse(bh_resize);
1651	}
1652
1653	mutex_init(&sbi->s_lock);
1654	sbi->cluster_size = sb->s_blocksize * sbi->sec_per_clus;
1655	sbi->cluster_bits = ffs(sbi->cluster_size) - 1;
1656	sbi->fats = bpb.fat_fats;
1657	sbi->fat_bits = 0;		/* Don't know yet */
1658	sbi->fat_start = bpb.fat_reserved;
1659	sbi->fat_length = bpb.fat_fat_length;
1660	sbi->root_cluster = 0;
1661	sbi->free_clusters = -1;	/* Don't know yet */
1662	sbi->free_clus_valid = 0;
1663	sbi->prev_free = FAT_START_ENT;
1664	sb->s_maxbytes = 0xffffffff;
1665	fat_time_fat2unix(sbi, &ts, 0, cpu_to_le16(FAT_DATE_MIN), 0);
1666	sb->s_time_min = ts.tv_sec;
1667
1668	fat_time_fat2unix(sbi, &ts, cpu_to_le16(FAT_TIME_MAX),
1669			  cpu_to_le16(FAT_DATE_MAX), 0);
1670	sb->s_time_max = ts.tv_sec;
1671
1672	if (!sbi->fat_length && bpb.fat32_length) {
1673		struct fat_boot_fsinfo *fsinfo;
1674		struct buffer_head *fsinfo_bh;
1675
1676		/* Must be FAT32 */
1677		sbi->fat_bits = 32;
1678		sbi->fat_length = bpb.fat32_length;
1679		sbi->root_cluster = bpb.fat32_root_cluster;
1680
1681		/* MC - if info_sector is 0, don't multiply by 0 */
1682		sbi->fsinfo_sector = bpb.fat32_info_sector;
1683		if (sbi->fsinfo_sector == 0)
1684			sbi->fsinfo_sector = 1;
1685
1686		fsinfo_bh = sb_bread(sb, sbi->fsinfo_sector);
1687		if (fsinfo_bh == NULL) {
1688			fat_msg(sb, KERN_ERR, "bread failed, FSINFO block"
1689			       " (sector = %lu)", sbi->fsinfo_sector);
1690			goto out_fail;
1691		}
1692
1693		fsinfo = (struct fat_boot_fsinfo *)fsinfo_bh->b_data;
1694		if (!IS_FSINFO(fsinfo)) {
1695			fat_msg(sb, KERN_WARNING, "Invalid FSINFO signature: "
1696			       "0x%08x, 0x%08x (sector = %lu)",
1697			       le32_to_cpu(fsinfo->signature1),
1698			       le32_to_cpu(fsinfo->signature2),
1699			       sbi->fsinfo_sector);
1700		} else {
1701			if (sbi->options.usefree)
1702				sbi->free_clus_valid = 1;
1703			sbi->free_clusters = le32_to_cpu(fsinfo->free_clusters);
1704			sbi->prev_free = le32_to_cpu(fsinfo->next_cluster);
1705		}
1706
1707		brelse(fsinfo_bh);
1708	}
1709
1710	/* interpret volume ID as a little endian 32 bit integer */
1711	if (is_fat32(sbi))
1712		sbi->vol_id = bpb.fat32_vol_id;
1713	else /* fat 16 or 12 */
1714		sbi->vol_id = bpb.fat16_vol_id;
1715
1716	__le32 vol_id_le = cpu_to_le32(sbi->vol_id);
1717	super_set_uuid(sb, (void *) &vol_id_le, sizeof(vol_id_le));
1718
1719	sbi->dir_per_block = sb->s_blocksize / sizeof(struct msdos_dir_entry);
1720	sbi->dir_per_block_bits = ffs(sbi->dir_per_block) - 1;
1721
1722	sbi->dir_start = sbi->fat_start + sbi->fats * sbi->fat_length;
1723	sbi->dir_entries = bpb.fat_dir_entries;
1724	if (sbi->dir_entries & (sbi->dir_per_block - 1)) {
1725		if (!silent)
1726			fat_msg(sb, KERN_ERR, "bogus number of directory entries"
1727			       " (%u)", sbi->dir_entries);
1728		goto out_invalid;
1729	}
1730
1731	rootdir_sectors = sbi->dir_entries
1732		* sizeof(struct msdos_dir_entry) / sb->s_blocksize;
1733	sbi->data_start = sbi->dir_start + rootdir_sectors;
1734	total_sectors = bpb.fat_sectors;
1735	if (total_sectors == 0)
1736		total_sectors = bpb.fat_total_sect;
1737
1738	total_clusters = (total_sectors - sbi->data_start) / sbi->sec_per_clus;
1739
1740	if (!is_fat32(sbi))
1741		sbi->fat_bits = (total_clusters > MAX_FAT12) ? 16 : 12;
1742
1743	/* some OSes set FAT_STATE_DIRTY and clean it on unmount. */
1744	if (is_fat32(sbi))
1745		sbi->dirty = bpb.fat32_state & FAT_STATE_DIRTY;
1746	else /* fat 16 or 12 */
1747		sbi->dirty = bpb.fat16_state & FAT_STATE_DIRTY;
1748
1749	/* check that FAT table does not overflow */
1750	fat_clusters = calc_fat_clusters(sb);
1751	total_clusters = min(total_clusters, fat_clusters - FAT_START_ENT);
1752	if (total_clusters > max_fat(sb)) {
1753		if (!silent)
1754			fat_msg(sb, KERN_ERR, "count of clusters too big (%u)",
1755			       total_clusters);
1756		goto out_invalid;
1757	}
1758
1759	sbi->max_cluster = total_clusters + FAT_START_ENT;
1760	/* check the free_clusters, it's not necessarily correct */
1761	if (sbi->free_clusters != -1 && sbi->free_clusters > total_clusters)
1762		sbi->free_clusters = -1;
1763	/* check the prev_free, it's not necessarily correct */
1764	sbi->prev_free %= sbi->max_cluster;
1765	if (sbi->prev_free < FAT_START_ENT)
1766		sbi->prev_free = FAT_START_ENT;
1767
1768	/* set up enough so that it can read an inode */
1769	fat_hash_init(sb);
1770	dir_hash_init(sb);
1771	fat_ent_access_init(sb);
1772
1773	/*
1774	 * The low byte of the first FAT entry must have the same value as
1775	 * the media field of the boot sector. But in real world, too many
1776	 * devices are writing wrong values. So, removed that validity check.
1777	 *
1778	 * The removed check compared the first FAT entry to a value dependent
1779	 * on the media field like this:
1780	 * == (0x0F00 | media), for FAT12
1781	 * == (0XFF00 | media), for FAT16
1782	 * == (0x0FFFFF | media), for FAT32
1783	 */
1784
1785	error = -EINVAL;
1786	sprintf(buf, "cp%d", sbi->options.codepage);
1787	sbi->nls_disk = load_nls(buf);
1788	if (!sbi->nls_disk) {
1789		fat_msg(sb, KERN_ERR, "codepage %s not found", buf);
1790		goto out_fail;
1791	}
1792
1793	/* FIXME: utf8 is using iocharset for upper/lower conversion */
1794	if (sbi->options.isvfat) {
1795		sbi->nls_io = load_nls(sbi->options.iocharset);
1796		if (!sbi->nls_io) {
1797			fat_msg(sb, KERN_ERR, "IO charset %s not found",
1798			       sbi->options.iocharset);
1799			goto out_fail;
1800		}
1801	}
1802
1803	error = -ENOMEM;
1804	fat_inode = new_inode(sb);
1805	if (!fat_inode)
1806		goto out_fail;
1807	sbi->fat_inode = fat_inode;
1808
1809	fsinfo_inode = new_inode(sb);
1810	if (!fsinfo_inode)
1811		goto out_fail;
1812	fsinfo_inode->i_ino = MSDOS_FSINFO_INO;
1813	sbi->fsinfo_inode = fsinfo_inode;
1814	insert_inode_hash(fsinfo_inode);
1815
1816	root_inode = new_inode(sb);
1817	if (!root_inode)
1818		goto out_fail;
1819	root_inode->i_ino = MSDOS_ROOT_INO;
1820	inode_set_iversion(root_inode, 1);
1821	error = fat_read_root(root_inode);
1822	if (error < 0) {
1823		iput(root_inode);
1824		goto out_fail;
1825	}
1826	error = -ENOMEM;
1827	insert_inode_hash(root_inode);
1828	fat_attach(root_inode, 0);
1829	sb->s_root = d_make_root(root_inode);
1830	if (!sb->s_root) {
1831		fat_msg(sb, KERN_ERR, "get root inode failed");
1832		goto out_fail;
1833	}
1834
1835	if (sbi->options.discard && !bdev_max_discard_sectors(sb->s_bdev))
1836		fat_msg(sb, KERN_WARNING,
1837			"mounting with \"discard\" option, but the device does not support discard");
1838
1839	fat_set_state(sb, 1, 0);
1840	return 0;
1841
1842out_invalid:
1843	error = -EINVAL;
1844	if (!silent)
1845		fat_msg(sb, KERN_INFO, "Can't find a valid FAT filesystem");
1846
1847out_fail:
1848	iput(fsinfo_inode);
1849	iput(fat_inode);
1850	unload_nls(sbi->nls_io);
1851	unload_nls(sbi->nls_disk);
1852	fat_reset_iocharset(&sbi->options);
1853	sb->s_fs_info = NULL;
1854	kfree(sbi);
1855	return error;
1856}
1857
1858EXPORT_SYMBOL_GPL(fat_fill_super);
1859
1860/*
1861 * helper function for fat_flush_inodes.  This writes both the inode
1862 * and the file data blocks, waiting for in flight data blocks before
1863 * the start of the call.  It does not wait for any io started
1864 * during the call
1865 */
1866static int writeback_inode(struct inode *inode)
1867{
1868
1869	int ret;
1870
1871	/* if we used wait=1, sync_inode_metadata waits for the io for the
1872	* inode to finish.  So wait=0 is sent down to sync_inode_metadata
1873	* and filemap_fdatawrite is used for the data blocks
1874	*/
1875	ret = sync_inode_metadata(inode, 0);
1876	if (!ret)
1877		ret = filemap_fdatawrite(inode->i_mapping);
1878	return ret;
1879}
1880
1881/*
1882 * write data and metadata corresponding to i1 and i2.  The io is
1883 * started but we do not wait for any of it to finish.
1884 *
1885 * filemap_flush is used for the block device, so if there is a dirty
1886 * page for a block already in flight, we will not wait and start the
1887 * io over again
1888 */
1889int fat_flush_inodes(struct super_block *sb, struct inode *i1, struct inode *i2)
1890{
1891	int ret = 0;
1892	if (!MSDOS_SB(sb)->options.flush)
1893		return 0;
1894	if (i1)
1895		ret = writeback_inode(i1);
1896	if (!ret && i2)
1897		ret = writeback_inode(i2);
1898	if (!ret)
1899		ret = sync_blockdev_nowait(sb->s_bdev);
1900	return ret;
1901}
1902EXPORT_SYMBOL_GPL(fat_flush_inodes);
1903
1904int fat_init_fs_context(struct fs_context *fc, bool is_vfat)
1905{
1906	struct fat_mount_options *opts;
1907
1908	opts = kzalloc(sizeof(*opts), GFP_KERNEL);
1909	if (!opts)
1910		return -ENOMEM;
1911
1912	opts->isvfat = is_vfat;
1913	opts->fs_uid = current_uid();
1914	opts->fs_gid = current_gid();
1915	opts->fs_fmask = opts->fs_dmask = current_umask();
1916	opts->allow_utime = -1;
1917	opts->codepage = fat_default_codepage;
1918	fat_reset_iocharset(opts);
1919	if (is_vfat) {
1920		opts->shortname = VFAT_SFN_DISPLAY_WINNT|VFAT_SFN_CREATE_WIN95;
1921		opts->rodir = 0;
1922	} else {
1923		opts->shortname = 0;
1924		opts->rodir = 1;
1925	}
1926	opts->name_check = 'n';
1927	opts->quiet = opts->showexec = opts->sys_immutable = opts->dotsOK =  0;
1928	opts->unicode_xlate = 0;
1929	opts->numtail = 1;
1930	opts->usefree = opts->nocase = 0;
1931	opts->tz_set = 0;
1932	opts->nfs = 0;
1933	opts->errors = FAT_ERRORS_RO;
1934	opts->debug = 0;
1935
1936	opts->utf8 = IS_ENABLED(CONFIG_FAT_DEFAULT_UTF8) && is_vfat;
1937
1938	fc->fs_private = opts;
1939	/* fc->ops assigned by caller */
1940
1941	return 0;
1942}
1943EXPORT_SYMBOL_GPL(fat_init_fs_context);
1944
1945void fat_free_fc(struct fs_context *fc)
1946{
1947	struct fat_mount_options *opts = fc->fs_private;
1948
1949	if (opts->iocharset != fat_default_iocharset)
1950		kfree(opts->iocharset);
1951	kfree(fc->fs_private);
1952}
1953EXPORT_SYMBOL_GPL(fat_free_fc);
1954
1955static int __init init_fat_fs(void)
1956{
1957	int err;
1958
1959	err = fat_cache_init();
1960	if (err)
1961		return err;
1962
1963	err = fat_init_inodecache();
1964	if (err)
1965		goto failed;
1966
1967	return 0;
1968
1969failed:
1970	fat_cache_destroy();
1971	return err;
1972}
1973
1974static void __exit exit_fat_fs(void)
1975{
1976	fat_cache_destroy();
1977	fat_destroy_inodecache();
1978}
1979
1980module_init(init_fat_fs)
1981module_exit(exit_fat_fs)
1982
1983MODULE_DESCRIPTION("Core FAT filesystem support");
1984MODULE_LICENSE("GPL");