// SPDX-License-Identifier: GPL-2.0-only

  /*
   *  linux/fs/fat/inode.c
   *
   *  Written 1992,1993 by Werner Almesberger
   *  VFAT extensions by Gordon Chaffee, merged with msdos fs by Henrik Storner
   *  Rewritten for the constant inumbers support by Al Viro
   *
   *  Fixes:
   *
   *	Max Cohan: Fixed invalid FSINFO offset when info_sector is 0
   */
  
  #include <linux/module.h>

  #include <linux/pagemap.h>

  #include <linux/mpage.h>

  #include <linux/vfs.h>

  #include <linux/seq_file.h>

  #include <linux/parser.h>

  #include <linux/uio.h>

  #include <linux/blkdev.h>

  #include <linux/backing-dev.h>

  #include <asm/unaligned.h>

  #include <linux/random.h>

  #include <linux/iversion.h>

  #include "fat.h"

  
  #ifndef CONFIG_FAT_DEFAULT_IOCHARSET
  /* if user don't select VFAT, this is undefined. */
  #define CONFIG_FAT_DEFAULT_IOCHARSET	""
  #endif

  #define KB_IN_SECTORS 2

  /* DOS dates from 1980/1/1 through 2107/12/31 */
  #define FAT_DATE_MIN (0<<9 | 1<<5 | 1)
  #define FAT_DATE_MAX (127<<9 | 12<<5 | 31)
  #define FAT_TIME_MAX (23<<11 | 59<<5 | 29)

  /*
   * A deserialized copy of the on-disk structure laid out in struct
   * fat_boot_sector.
   */
  struct fat_bios_param_block {
  	u16	fat_sector_size;
  	u8	fat_sec_per_clus;
  	u16	fat_reserved;
  	u8	fat_fats;
  	u16	fat_dir_entries;
  	u16	fat_sectors;
  	u16	fat_fat_length;
  	u32	fat_total_sect;
  
  	u8	fat16_state;
  	u32	fat16_vol_id;
  
  	u32	fat32_length;
  	u32	fat32_root_cluster;
  	u16	fat32_info_sector;
  	u8	fat32_state;
  	u32	fat32_vol_id;
  };

  static int fat_default_codepage = CONFIG_FAT_DEFAULT_CODEPAGE;
  static char fat_default_iocharset[] = CONFIG_FAT_DEFAULT_IOCHARSET;

  static struct fat_floppy_defaults {
  	unsigned nr_sectors;
  	unsigned sec_per_clus;
  	unsigned dir_entries;
  	unsigned media;
  	unsigned fat_length;
  } floppy_defaults[] = {
  {
  	.nr_sectors = 160 * KB_IN_SECTORS,
  	.sec_per_clus = 1,
  	.dir_entries = 64,
  	.media = 0xFE,
  	.fat_length = 1,
  },
  {
  	.nr_sectors = 180 * KB_IN_SECTORS,
  	.sec_per_clus = 1,
  	.dir_entries = 64,
  	.media = 0xFC,
  	.fat_length = 2,
  },
  {
  	.nr_sectors = 320 * KB_IN_SECTORS,
  	.sec_per_clus = 2,
  	.dir_entries = 112,
  	.media = 0xFF,
  	.fat_length = 1,
  },
  {
  	.nr_sectors = 360 * KB_IN_SECTORS,
  	.sec_per_clus = 2,
  	.dir_entries = 112,
  	.media = 0xFD,
  	.fat_length = 2,
  },
  };

  int fat_add_cluster(struct inode *inode)

  {
  	int err, cluster;
  
  	err = fat_alloc_clusters(inode, &cluster, 1);
  	if (err)
  		return err;
  	/* FIXME: this cluster should be added after data of this
  	 * cluster is writed */
  	err = fat_chain_add(inode, cluster, 1);
  	if (err)
  		fat_free_clusters(inode, cluster);
  	return err;
  }

  static inline int __fat_get_block(struct inode *inode, sector_t iblock,
  				  unsigned long *max_blocks,
  				  struct buffer_head *bh_result, int create)

  {
  	struct super_block *sb = inode->i_sb;

  	struct msdos_sb_info *sbi = MSDOS_SB(sb);

  	unsigned long mapped_blocks;

  	sector_t phys, last_block;

  	int err, offset;

  	err = fat_bmap(inode, iblock, &phys, &mapped_blocks, create, false);

  	if (err)
  		return err;
  	if (phys) {
  		map_bh(bh_result, sb, phys);

  		*max_blocks = min(mapped_blocks, *max_blocks);

  		return 0;
  	}
  	if (!create)
  		return 0;

  	if (iblock != MSDOS_I(inode)->mmu_private >> sb->s_blocksize_bits) {

  		fat_fs_error(sb, "corrupted file size (i_pos %lld, %lld)",

  			MSDOS_I(inode)->i_pos, MSDOS_I(inode)->mmu_private);

  		return -EIO;
  	}

  	last_block = inode->i_blocks >> (sb->s_blocksize_bits - 9);

  	offset = (unsigned long)iblock & (sbi->sec_per_clus - 1);

  	/*
  	 * allocate a cluster according to the following.
  	 * 1) no more available blocks
  	 * 2) not part of fallocate region
  	 */
  	if (!offset && !(iblock < last_block)) {

  		/* TODO: multiple cluster allocation would be desirable. */

  		err = fat_add_cluster(inode);
  		if (err)
  			return err;
  	}

  	/* available blocks on this cluster */
  	mapped_blocks = sbi->sec_per_clus - offset;
  
  	*max_blocks = min(mapped_blocks, *max_blocks);
  	MSDOS_I(inode)->mmu_private += *max_blocks << sb->s_blocksize_bits;

  	err = fat_bmap(inode, iblock, &phys, &mapped_blocks, create, false);

  	if (err)
  		return err;

  	if (!phys) {
  		fat_fs_error(sb,
  			     "invalid FAT chain (i_pos %lld, last_block %llu)",
  			     MSDOS_I(inode)->i_pos,
  			     (unsigned long long)last_block);
  		return -EIO;
  	}

  	BUG_ON(*max_blocks != mapped_blocks);

  	set_buffer_new(bh_result);
  	map_bh(bh_result, sb, phys);

  	return 0;
  }

  static int fat_get_block(struct inode *inode, sector_t iblock,
  			 struct buffer_head *bh_result, int create)

  {
  	struct super_block *sb = inode->i_sb;

  	unsigned long max_blocks = bh_result->b_size >> inode->i_blkbits;

  	int err;

  	err = __fat_get_block(inode, iblock, &max_blocks, bh_result, create);

  	if (err)
  		return err;
  	bh_result->b_size = max_blocks << sb->s_blocksize_bits;
  	return 0;
  }

  static int fat_writepage(struct page *page, struct writeback_control *wbc)
  {
  	return block_write_full_page(page, fat_get_block, wbc);
  }

  static int fat_writepages(struct address_space *mapping,
  			  struct writeback_control *wbc)
  {
  	return mpage_writepages(mapping, wbc, fat_get_block);
  }

  static int fat_readpage(struct file *file, struct page *page)
  {

  	return mpage_readpage(page, fat_get_block);
  }

  static void fat_readahead(struct readahead_control *rac)

  {

  	mpage_readahead(rac, fat_get_block);

  }

  static void fat_write_failed(struct address_space *mapping, loff_t to)
  {
  	struct inode *inode = mapping->host;
  
  	if (to > inode->i_size) {

  		truncate_pagecache(inode, inode->i_size);

  		fat_truncate_blocks(inode, inode->i_size);
  	}
  }

  static int fat_write_begin(struct file *file, struct address_space *mapping,
  			loff_t pos, unsigned len, unsigned flags,
  			struct page **pagep, void **fsdata)

  {

  	int err;

  	*pagep = NULL;

  	err = cont_write_begin(file, mapping, pos, len, flags,

  				pagep, fsdata, fat_get_block,

  				&MSDOS_I(mapping->host)->mmu_private);

  	if (err < 0)
  		fat_write_failed(mapping, pos + len);
  	return err;

  }

  static int fat_write_end(struct file *file, struct address_space *mapping,
  			loff_t pos, unsigned len, unsigned copied,
  			struct page *pagep, void *fsdata)

  {

  	struct inode *inode = mapping->host;
  	int err;
  	err = generic_write_end(file, mapping, pos, len, copied, pagep, fsdata);

  	if (err < len)
  		fat_write_failed(mapping, pos + len);

  	if (!(err < 0) && !(MSDOS_I(inode)->i_attrs & ATTR_ARCH)) {

  		fat_truncate_time(inode, NULL, S_CTIME|S_MTIME);

  		MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
  		mark_inode_dirty(inode);
  	}
  	return err;
  }

  static ssize_t fat_direct_IO(struct kiocb *iocb, struct iov_iter *iter)

  {
  	struct file *file = iocb->ki_filp;

  	struct address_space *mapping = file->f_mapping;
  	struct inode *inode = mapping->host;

  	size_t count = iov_iter_count(iter);

  	loff_t offset = iocb->ki_pos;

  	ssize_t ret;

  	if (iov_iter_rw(iter) == WRITE) {

  		/*

  		 * FIXME: blockdev_direct_IO() doesn't use ->write_begin(),

  		 * so we need to update the ->mmu_private to block boundary.
  		 *
  		 * But we must fill the remaining area or hole by nul for
  		 * updating ->mmu_private.

  		 *
  		 * Return 0, and fallback to normal buffered write.

  		 */

  		loff_t size = offset + count;

  		if (MSDOS_I(inode)->mmu_private < size)

  			return 0;

  	}
  
  	/*
  	 * FAT need to use the DIO_LOCKING for avoiding the race
  	 * condition of fat_get_block() and ->truncate().
  	 */

  	ret = blockdev_direct_IO(iocb, inode, iter, fat_get_block);

  	if (ret < 0 && iov_iter_rw(iter) == WRITE)

  		fat_write_failed(mapping, offset + count);

  
  	return ret;

  }

  static int fat_get_block_bmap(struct inode *inode, sector_t iblock,
  		struct buffer_head *bh_result, int create)
  {
  	struct super_block *sb = inode->i_sb;
  	unsigned long max_blocks = bh_result->b_size >> inode->i_blkbits;
  	int err;
  	sector_t bmap;
  	unsigned long mapped_blocks;
  
  	BUG_ON(create != 0);
  
  	err = fat_bmap(inode, iblock, &bmap, &mapped_blocks, create, true);
  	if (err)
  		return err;
  
  	if (bmap) {
  		map_bh(bh_result, sb, bmap);
  		max_blocks = min(mapped_blocks, max_blocks);
  	}
  
  	bh_result->b_size = max_blocks << sb->s_blocksize_bits;
  
  	return 0;
  }

  static sector_t _fat_bmap(struct address_space *mapping, sector_t block)
  {

  	sector_t blocknr;
  
  	/* fat_get_cluster() assumes the requested blocknr isn't truncated. */

  	down_read(&MSDOS_I(mapping->host)->truncate_lock);

  	blocknr = generic_block_bmap(mapping, block, fat_get_block_bmap);

  	up_read(&MSDOS_I(mapping->host)->truncate_lock);

  
  	return blocknr;

  }

  /*
   * fat_block_truncate_page() zeroes out a mapping from file offset `from'
   * up to the end of the block which corresponds to `from'.
   * This is required during truncate to physically zeroout the tail end
   * of that block so it doesn't yield old data if the file is later grown.
   * Also, avoid causing failure from fsx for cases of "data past EOF"
   */
  int fat_block_truncate_page(struct inode *inode, loff_t from)
  {
  	return block_truncate_page(inode->i_mapping, from, fat_get_block);
  }

  static const struct address_space_operations fat_aops = {

  	.readpage	= fat_readpage,

  	.readahead	= fat_readahead,

  	.writepage	= fat_writepage,

  	.writepages	= fat_writepages,

  	.write_begin	= fat_write_begin,
  	.write_end	= fat_write_end,

  	.direct_IO	= fat_direct_IO,

  	.bmap		= _fat_bmap
  };
  
  /*
   * New FAT inode stuff. We do the following:
   *	a) i_ino is constant and has nothing with on-disk location.
   *	b) FAT manages its own cache of directory entries.
   *	c) *This* cache is indexed by on-disk location.
   *	d) inode has an associated directory entry, all right, but
   *		it may be unhashed.
   *	e) currently entries are stored within struct inode. That should
   *		change.
   *	f) we deal with races in the following way:
   *		1. readdir() and lookup() do FAT-dir-cache lookup.
   *		2. rename() unhashes the F-d-c entry and rehashes it in
   *			a new place.
   *		3. unlink() and rmdir() unhash F-d-c entry.
   *		4. fat_write_inode() checks whether the thing is unhashed.
   *			If it is we silently return. If it isn't we do bread(),
   *			check if the location is still valid and retry if it
   *			isn't. Otherwise we do changes.
   *		5. Spinlock is used to protect hash/unhash/location check/lookup

   *		6. fat_evict_inode() unhashes the F-d-c entry.

   *		7. lookup() and readdir() do igrab() if they find a F-d-c entry
   *			and consider negative result as cache miss.
   */
  
  static void fat_hash_init(struct super_block *sb)
  {
  	struct msdos_sb_info *sbi = MSDOS_SB(sb);
  	int i;
  
  	spin_lock_init(&sbi->inode_hash_lock);
  	for (i = 0; i < FAT_HASH_SIZE; i++)
  		INIT_HLIST_HEAD(&sbi->inode_hashtable[i]);
  }

  static inline unsigned long fat_hash(loff_t i_pos)

  {

  	return hash_32(i_pos, FAT_HASH_BITS);

  }

  static void dir_hash_init(struct super_block *sb)
  {
  	struct msdos_sb_info *sbi = MSDOS_SB(sb);
  	int i;
  
  	spin_lock_init(&sbi->dir_hash_lock);
  	for (i = 0; i < FAT_HASH_SIZE; i++)
  		INIT_HLIST_HEAD(&sbi->dir_hashtable[i]);
  }

  void fat_attach(struct inode *inode, loff_t i_pos)
  {

  	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);

  	if (inode->i_ino != MSDOS_ROOT_INO) {
  		struct hlist_head *head =   sbi->inode_hashtable
  					  + fat_hash(i_pos);
  
  		spin_lock(&sbi->inode_hash_lock);
  		MSDOS_I(inode)->i_pos = i_pos;
  		hlist_add_head(&MSDOS_I(inode)->i_fat_hash, head);
  		spin_unlock(&sbi->inode_hash_lock);
  	}
  
  	/* If NFS support is enabled, cache the mapping of start cluster
  	 * to directory inode. This is used during reconnection of
  	 * dentries to the filesystem root.
  	 */
  	if (S_ISDIR(inode->i_mode) && sbi->options.nfs) {
  		struct hlist_head *d_head = sbi->dir_hashtable;
  		d_head += fat_dir_hash(MSDOS_I(inode)->i_logstart);
  
  		spin_lock(&sbi->dir_hash_lock);
  		hlist_add_head(&MSDOS_I(inode)->i_dir_hash, d_head);
  		spin_unlock(&sbi->dir_hash_lock);
  	}

  }

  EXPORT_SYMBOL_GPL(fat_attach);

  
  void fat_detach(struct inode *inode)
  {
  	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
  	spin_lock(&sbi->inode_hash_lock);
  	MSDOS_I(inode)->i_pos = 0;
  	hlist_del_init(&MSDOS_I(inode)->i_fat_hash);
  	spin_unlock(&sbi->inode_hash_lock);

  
  	if (S_ISDIR(inode->i_mode) && sbi->options.nfs) {
  		spin_lock(&sbi->dir_hash_lock);
  		hlist_del_init(&MSDOS_I(inode)->i_dir_hash);
  		spin_unlock(&sbi->dir_hash_lock);
  	}

  }

  EXPORT_SYMBOL_GPL(fat_detach);

  
  struct inode *fat_iget(struct super_block *sb, loff_t i_pos)
  {
  	struct msdos_sb_info *sbi = MSDOS_SB(sb);

  	struct hlist_head *head = sbi->inode_hashtable + fat_hash(i_pos);

  	struct msdos_inode_info *i;
  	struct inode *inode = NULL;
  
  	spin_lock(&sbi->inode_hash_lock);

  	hlist_for_each_entry(i, head, i_fat_hash) {

  		BUG_ON(i->vfs_inode.i_sb != sb);
  		if (i->i_pos != i_pos)
  			continue;
  		inode = igrab(&i->vfs_inode);
  		if (inode)
  			break;
  	}
  	spin_unlock(&sbi->inode_hash_lock);
  	return inode;
  }
  
  static int is_exec(unsigned char *extension)
  {

  	unsigned char exe_extensions[] = "EXECOMBAT", *walk;

  
  	for (walk = exe_extensions; *walk; walk += 3)
  		if (!strncmp(extension, walk, 3))
  			return 1;
  	return 0;
  }
  
  static int fat_calc_dir_size(struct inode *inode)
  {
  	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
  	int ret, fclus, dclus;
  
  	inode->i_size = 0;
  	if (MSDOS_I(inode)->i_start == 0)
  		return 0;
  
  	ret = fat_get_cluster(inode, FAT_ENT_EOF, &fclus, &dclus);
  	if (ret < 0)
  		return ret;
  	inode->i_size = (fclus + 1) << sbi->cluster_bits;
  
  	return 0;
  }

  static int fat_validate_dir(struct inode *dir)
  {
  	struct super_block *sb = dir->i_sb;
  
  	if (dir->i_nlink < 2) {
  		/* Directory should have "."/".." entries at least. */
  		fat_fs_error(sb, "corrupted directory (invalid entries)");
  		return -EIO;
  	}
  	if (MSDOS_I(dir)->i_start == 0 ||
  	    MSDOS_I(dir)->i_start == MSDOS_SB(sb)->root_cluster) {
  		/* Directory should point valid cluster. */
  		fat_fs_error(sb, "corrupted directory (invalid i_start)");
  		return -EIO;
  	}
  	return 0;
  }

  /* doesn't deal with root inode */

  int fat_fill_inode(struct inode *inode, struct msdos_dir_entry *de)

  {
  	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
  	int error;
  
  	MSDOS_I(inode)->i_pos = 0;
  	inode->i_uid = sbi->options.fs_uid;
  	inode->i_gid = sbi->options.fs_gid;

  	inode_inc_iversion(inode);

  	inode->i_generation = prandom_u32();

  
  	if ((de->attr & ATTR_DIR) && !IS_FREE(de->name)) {
  		inode->i_generation &= ~1;

  		inode->i_mode = fat_make_mode(sbi, de->attr, S_IRWXUGO);

  		inode->i_op = sbi->dir_ops;
  		inode->i_fop = &fat_dir_operations;

  		MSDOS_I(inode)->i_start = fat_get_start(sbi, de);

  		MSDOS_I(inode)->i_logstart = MSDOS_I(inode)->i_start;
  		error = fat_calc_dir_size(inode);
  		if (error < 0)
  			return error;
  		MSDOS_I(inode)->mmu_private = inode->i_size;

  		set_nlink(inode, fat_subdirs(inode));

  
  		error = fat_validate_dir(inode);
  		if (error < 0)
  			return error;

  	} else { /* not a directory */
  		inode->i_generation |= 1;

  		inode->i_mode = fat_make_mode(sbi, de->attr,
  			((sbi->options.showexec && !is_exec(de->name + 8))
  			 ? S_IRUGO|S_IWUGO : S_IRWXUGO));

  		MSDOS_I(inode)->i_start = fat_get_start(sbi, de);

  
  		MSDOS_I(inode)->i_logstart = MSDOS_I(inode)->i_start;
  		inode->i_size = le32_to_cpu(de->size);
  		inode->i_op = &fat_file_inode_operations;
  		inode->i_fop = &fat_file_operations;
  		inode->i_mapping->a_ops = &fat_aops;
  		MSDOS_I(inode)->mmu_private = inode->i_size;
  	}
  	if (de->attr & ATTR_SYS) {
  		if (sbi->options.sys_immutable)
  			inode->i_flags |= S_IMMUTABLE;
  	}

  	fat_save_attrs(inode, de->attr);

  	inode->i_blocks = ((inode->i_size + (sbi->cluster_size - 1))
  			   & ~((loff_t)sbi->cluster_size - 1)) >> 9;

  	fat_time_fat2unix(sbi, &inode->i_mtime, de->time, de->date, 0);

  	if (sbi->options.isvfat) {

  		fat_time_fat2unix(sbi, &inode->i_ctime, de->ctime,

  				  de->cdate, de->ctime_cs);

  		fat_time_fat2unix(sbi, &inode->i_atime, 0, de->adate, 0);

  	} else

  		fat_truncate_time(inode, &inode->i_mtime, S_ATIME|S_CTIME);

  
  	return 0;
  }

  static inline void fat_lock_build_inode(struct msdos_sb_info *sbi)
  {
  	if (sbi->options.nfs == FAT_NFS_NOSTALE_RO)
  		mutex_lock(&sbi->nfs_build_inode_lock);
  }
  
  static inline void fat_unlock_build_inode(struct msdos_sb_info *sbi)
  {
  	if (sbi->options.nfs == FAT_NFS_NOSTALE_RO)
  		mutex_unlock(&sbi->nfs_build_inode_lock);
  }

  struct inode *fat_build_inode(struct super_block *sb,
  			struct msdos_dir_entry *de, loff_t i_pos)
  {
  	struct inode *inode;
  	int err;

  	fat_lock_build_inode(MSDOS_SB(sb));

  	inode = fat_iget(sb, i_pos);
  	if (inode)
  		goto out;
  	inode = new_inode(sb);
  	if (!inode) {
  		inode = ERR_PTR(-ENOMEM);
  		goto out;
  	}
  	inode->i_ino = iunique(sb, MSDOS_ROOT_INO);

  	inode_set_iversion(inode, 1);

  	err = fat_fill_inode(inode, de);
  	if (err) {
  		iput(inode);
  		inode = ERR_PTR(err);
  		goto out;
  	}
  	fat_attach(inode, i_pos);
  	insert_inode_hash(inode);
  out:

  	fat_unlock_build_inode(MSDOS_SB(sb));

  	return inode;
  }

  EXPORT_SYMBOL_GPL(fat_build_inode);

  static int __fat_write_inode(struct inode *inode, int wait);
  
  static void fat_free_eofblocks(struct inode *inode)
  {
  	/* Release unwritten fallocated blocks on inode eviction. */
  	if ((inode->i_blocks << 9) >
  			round_up(MSDOS_I(inode)->mmu_private,
  				MSDOS_SB(inode->i_sb)->cluster_size)) {
  		int err;
  
  		fat_truncate_blocks(inode, MSDOS_I(inode)->mmu_private);
  		/* Fallocate results in updating the i_start/iogstart
  		 * for the zero byte file. So, make it return to
  		 * original state during evict and commit it to avoid
  		 * any corruption on the next access to the cluster
  		 * chain for the file.
  		 */
  		err = __fat_write_inode(inode, inode_needs_sync(inode));
  		if (err) {
  			fat_msg(inode->i_sb, KERN_WARNING, "Failed to "
  					"update on disk inode for unused "
  					"fallocated blocks, inode could be "
  					"corrupted. Please run fsck");
  		}
  
  	}
  }

  static void fat_evict_inode(struct inode *inode)

  {

  	truncate_inode_pages_final(&inode->i_data);

  	if (!inode->i_nlink) {
  		inode->i_size = 0;
  		fat_truncate_blocks(inode, 0);

  	} else
  		fat_free_eofblocks(inode);

  	invalidate_inode_buffers(inode);

  	clear_inode(inode);

  	fat_cache_inval_inode(inode);

  	fat_detach(inode);

  }

  static void fat_set_state(struct super_block *sb,
  			unsigned int set, unsigned int force)
  {
  	struct buffer_head *bh;
  	struct fat_boot_sector *b;

  	struct msdos_sb_info *sbi = MSDOS_SB(sb);

  
  	/* do not change any thing if mounted read only */

  	if (sb_rdonly(sb) && !force)

  		return;
  
  	/* do not change state if fs was dirty */
  	if (sbi->dirty) {
  		/* warn only on set (mount). */
  		if (set)
  			fat_msg(sb, KERN_WARNING, "Volume was not properly "
  				"unmounted. Some data may be corrupt. "
  				"Please run fsck.");
  		return;
  	}
  
  	bh = sb_bread(sb, 0);
  	if (bh == NULL) {
  		fat_msg(sb, KERN_ERR, "unable to read boot sector "
  			"to mark fs as dirty");
  		return;
  	}
  
  	b = (struct fat_boot_sector *) bh->b_data;

  	if (is_fat32(sbi)) {

  		if (set)
  			b->fat32.state |= FAT_STATE_DIRTY;
  		else
  			b->fat32.state &= ~FAT_STATE_DIRTY;
  	} else /* fat 16 and 12 */ {
  		if (set)
  			b->fat16.state |= FAT_STATE_DIRTY;
  		else
  			b->fat16.state &= ~FAT_STATE_DIRTY;
  	}
  
  	mark_buffer_dirty(bh);
  	sync_dirty_buffer(bh);
  	brelse(bh);
  }

  static void fat_reset_iocharset(struct fat_mount_options *opts)
  {
  	if (opts->iocharset != fat_default_iocharset) {
  		/* Note: opts->iocharset can be NULL here */
  		kfree(opts->iocharset);
  		opts->iocharset = fat_default_iocharset;
  	}
  }

  static void delayed_free(struct rcu_head *p)
  {
  	struct msdos_sb_info *sbi = container_of(p, struct msdos_sb_info, rcu);
  	unload_nls(sbi->nls_disk);
  	unload_nls(sbi->nls_io);

  	fat_reset_iocharset(&sbi->options);

  	kfree(sbi);
  }

  static void fat_put_super(struct super_block *sb)
  {
  	struct msdos_sb_info *sbi = MSDOS_SB(sb);

  	fat_set_state(sb, 0, 0);

  	iput(sbi->fsinfo_inode);

  	iput(sbi->fat_inode);

  	call_rcu(&sbi->rcu, delayed_free);

  }

  static struct kmem_cache *fat_inode_cachep;

  
  static struct inode *fat_alloc_inode(struct super_block *sb)
  {
  	struct msdos_inode_info *ei;

  	ei = kmem_cache_alloc(fat_inode_cachep, GFP_NOFS);

  	if (!ei)
  		return NULL;

  
  	init_rwsem(&ei->truncate_lock);

  	/* Zeroing to allow iput() even if partial initialized inode. */
  	ei->mmu_private = 0;
  	ei->i_start = 0;
  	ei->i_logstart = 0;
  	ei->i_attrs = 0;
  	ei->i_pos = 0;

  	return &ei->vfs_inode;
  }

  static void fat_free_inode(struct inode *inode)

  {
  	kmem_cache_free(fat_inode_cachep, MSDOS_I(inode));
  }

  static void init_once(void *foo)

  {
  	struct msdos_inode_info *ei = (struct msdos_inode_info *)foo;

  	spin_lock_init(&ei->cache_lru_lock);
  	ei->nr_caches = 0;
  	ei->cache_valid_id = FAT_CACHE_VALID + 1;
  	INIT_LIST_HEAD(&ei->cache_lru);
  	INIT_HLIST_NODE(&ei->i_fat_hash);

  	INIT_HLIST_NODE(&ei->i_dir_hash);

  	inode_init_once(&ei->vfs_inode);

  }
  
  static int __init fat_init_inodecache(void)
  {
  	fat_inode_cachep = kmem_cache_create("fat_inode_cache",
  					     sizeof(struct msdos_inode_info),

  					     0, (SLAB_RECLAIM_ACCOUNT|

  						SLAB_MEM_SPREAD|SLAB_ACCOUNT),

  					     init_once);

  	if (fat_inode_cachep == NULL)
  		return -ENOMEM;
  	return 0;
  }
  
  static void __exit fat_destroy_inodecache(void)
  {

  	/*
  	 * Make sure all delayed rcu free inodes are flushed before we
  	 * destroy cache.
  	 */
  	rcu_barrier();

  	kmem_cache_destroy(fat_inode_cachep);

  }
  
  static int fat_remount(struct super_block *sb, int *flags, char *data)
  {

  	bool new_rdonly;

  	struct msdos_sb_info *sbi = MSDOS_SB(sb);

  	*flags |= SB_NODIRATIME | (sbi->options.isvfat ? 0 : SB_NOATIME);

  	sync_filesystem(sb);

  	/* make sure we update state on remount. */

  	new_rdonly = *flags & SB_RDONLY;

  	if (new_rdonly != sb_rdonly(sb)) {

  		if (new_rdonly)
  			fat_set_state(sb, 0, 0);
  		else
  			fat_set_state(sb, 1, 1);
  	}

  	return 0;
  }

  static int fat_statfs(struct dentry *dentry, struct kstatfs *buf)

  {

  	struct super_block *sb = dentry->d_sb;
  	struct msdos_sb_info *sbi = MSDOS_SB(sb);
  	u64 id = huge_encode_dev(sb->s_bdev->bd_dev);

  
  	/* If the count of free cluster is still unknown, counts it here. */

  	if (sbi->free_clusters == -1 || !sbi->free_clus_valid) {

  		int err = fat_count_free_clusters(dentry->d_sb);

  		if (err)
  			return err;
  	}

  	buf->f_type = dentry->d_sb->s_magic;

  	buf->f_bsize = sbi->cluster_size;
  	buf->f_blocks = sbi->max_cluster - FAT_START_ENT;
  	buf->f_bfree = sbi->free_clusters;
  	buf->f_bavail = sbi->free_clusters;

  	buf->f_fsid = u64_to_fsid(id);

  	buf->f_namelen =
  		(sbi->options.isvfat ? FAT_LFN_LEN : 12) * NLS_MAX_CHARSET_SIZE;

  
  	return 0;
  }

  static int __fat_write_inode(struct inode *inode, int wait)

  {
  	struct super_block *sb = inode->i_sb;
  	struct msdos_sb_info *sbi = MSDOS_SB(sb);
  	struct buffer_head *bh;
  	struct msdos_dir_entry *raw_entry;
  	loff_t i_pos;

  	sector_t blocknr;
  	int err, offset;

  	if (inode->i_ino == MSDOS_ROOT_INO)
  		return 0;

  retry:

  	i_pos = fat_i_pos_read(sbi, inode);
  	if (!i_pos)

  		return 0;

  	fat_get_blknr_offset(sbi, i_pos, &blocknr, &offset);
  	bh = sb_bread(sb, blocknr);

  	if (!bh) {

  		fat_msg(sb, KERN_ERR, "unable to read inode block "
  		       "for updating (i_pos %lld)", i_pos);

  		return -EIO;

  	}
  	spin_lock(&sbi->inode_hash_lock);
  	if (i_pos != MSDOS_I(inode)->i_pos) {
  		spin_unlock(&sbi->inode_hash_lock);
  		brelse(bh);

  		goto retry;
  	}

  	raw_entry = &((struct msdos_dir_entry *) (bh->b_data))[offset];

  	if (S_ISDIR(inode->i_mode))
  		raw_entry->size = 0;
  	else
  		raw_entry->size = cpu_to_le32(inode->i_size);

  	raw_entry->attr = fat_make_attrs(inode);

  	fat_set_start(raw_entry, MSDOS_I(inode)->i_logstart);

  	fat_time_unix2fat(sbi, &inode->i_mtime, &raw_entry->time,

  			  &raw_entry->date, NULL);

  	if (sbi->options.isvfat) {

  		__le16 atime;

  		fat_time_unix2fat(sbi, &inode->i_ctime, &raw_entry->ctime,

  				  &raw_entry->cdate, &raw_entry->ctime_cs);

  		fat_time_unix2fat(sbi, &inode->i_atime, &atime,

  				  &raw_entry->adate, NULL);

  	}
  	spin_unlock(&sbi->inode_hash_lock);
  	mark_buffer_dirty(bh);

  	err = 0;

  	if (wait)
  		err = sync_dirty_buffer(bh);
  	brelse(bh);

  	return err;
  }

  static int fat_write_inode(struct inode *inode, struct writeback_control *wbc)
  {

  	int err;
  
  	if (inode->i_ino == MSDOS_FSINFO_INO) {
  		struct super_block *sb = inode->i_sb;

  		mutex_lock(&MSDOS_SB(sb)->s_lock);

  		err = fat_clusters_flush(sb);

  		mutex_unlock(&MSDOS_SB(sb)->s_lock);

  	} else
  		err = __fat_write_inode(inode, wbc->sync_mode == WB_SYNC_ALL);
  
  	return err;

  }

  int fat_sync_inode(struct inode *inode)
  {

  	return __fat_write_inode(inode, 1);

  }

  EXPORT_SYMBOL_GPL(fat_sync_inode);

  static int fat_show_options(struct seq_file *m, struct dentry *root);

  static const struct super_operations fat_sops = {

  	.alloc_inode	= fat_alloc_inode,

  	.free_inode	= fat_free_inode,

  	.write_inode	= fat_write_inode,

  	.evict_inode	= fat_evict_inode,

  	.put_super	= fat_put_super,
  	.statfs		= fat_statfs,

  	.remount_fs	= fat_remount,

  	.show_options	= fat_show_options,
  };

  static int fat_show_options(struct seq_file *m, struct dentry *root)

  {

  	struct msdos_sb_info *sbi = MSDOS_SB(root->d_sb);

  	struct fat_mount_options *opts = &sbi->options;
  	int isvfat = opts->isvfat;

  	if (!uid_eq(opts->fs_uid, GLOBAL_ROOT_UID))
  		seq_printf(m, ",uid=%u",
  				from_kuid_munged(&init_user_ns, opts->fs_uid));
  	if (!gid_eq(opts->fs_gid, GLOBAL_ROOT_GID))
  		seq_printf(m, ",gid=%u",
  				from_kgid_munged(&init_user_ns, opts->fs_gid));

  	seq_printf(m, ",fmask=%04o", opts->fs_fmask);
  	seq_printf(m, ",dmask=%04o", opts->fs_dmask);

  	if (opts->allow_utime)
  		seq_printf(m, ",allow_utime=%04o", opts->allow_utime);

  	if (sbi->nls_disk)

  		/* strip "cp" prefix from displayed option */
  		seq_printf(m, ",codepage=%s", &sbi->nls_disk->charset[2]);

  	if (isvfat) {
  		if (sbi->nls_io)
  			seq_printf(m, ",iocharset=%s", sbi->nls_io->charset);
  
  		switch (opts->shortname) {
  		case VFAT_SFN_DISPLAY_WIN95 | VFAT_SFN_CREATE_WIN95:
  			seq_puts(m, ",shortname=win95");
  			break;
  		case VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WINNT:
  			seq_puts(m, ",shortname=winnt");
  			break;
  		case VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WIN95:
  			seq_puts(m, ",shortname=mixed");
  			break;
  		case VFAT_SFN_DISPLAY_LOWER | VFAT_SFN_CREATE_WIN95:

  			seq_puts(m, ",shortname=lower");

  			break;
  		default:
  			seq_puts(m, ",shortname=unknown");
  			break;
  		}
  	}
  	if (opts->name_check != 'n')
  		seq_printf(m, ",check=%c", opts->name_check);

  	if (opts->usefree)
  		seq_puts(m, ",usefree");

  	if (opts->quiet)
  		seq_puts(m, ",quiet");
  	if (opts->showexec)
  		seq_puts(m, ",showexec");
  	if (opts->sys_immutable)
  		seq_puts(m, ",sys_immutable");
  	if (!isvfat) {
  		if (opts->dotsOK)
  			seq_puts(m, ",dotsOK=yes");
  		if (opts->nocase)
  			seq_puts(m, ",nocase");
  	} else {
  		if (opts->utf8)
  			seq_puts(m, ",utf8");
  		if (opts->unicode_xlate)
  			seq_puts(m, ",uni_xlate");
  		if (!opts->numtail)
  			seq_puts(m, ",nonumtail");

  		if (opts->rodir)
  			seq_puts(m, ",rodir");

  	}

  	if (opts->flush)

  		seq_puts(m, ",flush");

  	if (opts->tz_set) {
  		if (opts->time_offset)
  			seq_printf(m, ",time_offset=%d", opts->time_offset);
  		else
  			seq_puts(m, ",tz=UTC");
  	}

  	if (opts->errors == FAT_ERRORS_CONT)
  		seq_puts(m, ",errors=continue");
  	else if (opts->errors == FAT_ERRORS_PANIC)
  		seq_puts(m, ",errors=panic");
  	else
  		seq_puts(m, ",errors=remount-ro");

  	if (opts->nfs == FAT_NFS_NOSTALE_RO)
  		seq_puts(m, ",nfs=nostale_ro");
  	else if (opts->nfs)
  		seq_puts(m, ",nfs=stale_rw");

  	if (opts->discard)
  		seq_puts(m, ",discard");

  	if (opts->dos1xfloppy)
  		seq_puts(m, ",dos1xfloppy");

  
  	return 0;
  }
  
  enum {
  	Opt_check_n, Opt_check_r, Opt_check_s, Opt_uid, Opt_gid,

  	Opt_umask, Opt_dmask, Opt_fmask, Opt_allow_utime, Opt_codepage,
  	Opt_usefree, Opt_nocase, Opt_quiet, Opt_showexec, Opt_debug,
  	Opt_immutable, Opt_dots, Opt_nodots,

  	Opt_charset, Opt_shortname_lower, Opt_shortname_win95,
  	Opt_shortname_winnt, Opt_shortname_mixed, Opt_utf8_no, Opt_utf8_yes,
  	Opt_uni_xl_no, Opt_uni_xl_yes, Opt_nonumtail_no, Opt_nonumtail_yes,

  	Opt_obsolete, Opt_flush, Opt_tz_utc, Opt_rodir, Opt_err_cont,

  	Opt_err_panic, Opt_err_ro, Opt_discard, Opt_nfs, Opt_time_offset,

  	Opt_nfs_stale_rw, Opt_nfs_nostale_ro, Opt_err, Opt_dos1xfloppy,

  };

  static const match_table_t fat_tokens = {

  	{Opt_check_r, "check=relaxed"},
  	{Opt_check_s, "check=strict"},
  	{Opt_check_n, "check=normal"},
  	{Opt_check_r, "check=r"},
  	{Opt_check_s, "check=s"},
  	{Opt_check_n, "check=n"},
  	{Opt_uid, "uid=%u"},
  	{Opt_gid, "gid=%u"},
  	{Opt_umask, "umask=%o"},
  	{Opt_dmask, "dmask=%o"},
  	{Opt_fmask, "fmask=%o"},

  	{Opt_allow_utime, "allow_utime=%o"},

  	{Opt_codepage, "codepage=%u"},

  	{Opt_usefree, "usefree"},

  	{Opt_nocase, "nocase"},
  	{Opt_quiet, "quiet"},
  	{Opt_showexec, "showexec"},
  	{Opt_debug, "debug"},
  	{Opt_immutable, "sys_immutable"},

  	{Opt_flush, "flush"},
  	{Opt_tz_utc, "tz=UTC"},

  	{Opt_time_offset, "time_offset=%d"},

  	{Opt_err_cont, "errors=continue"},
  	{Opt_err_panic, "errors=panic"},
  	{Opt_err_ro, "errors=remount-ro"},

  	{Opt_discard, "discard"},

  	{Opt_nfs_stale_rw, "nfs"},
  	{Opt_nfs_stale_rw, "nfs=stale_rw"},
  	{Opt_nfs_nostale_ro, "nfs=nostale_ro"},

  	{Opt_dos1xfloppy, "dos1xfloppy"},

  	{Opt_obsolete, "conv=binary"},
  	{Opt_obsolete, "conv=text"},
  	{Opt_obsolete, "conv=auto"},
  	{Opt_obsolete, "conv=b"},
  	{Opt_obsolete, "conv=t"},
  	{Opt_obsolete, "conv=a"},
  	{Opt_obsolete, "fat=%u"},
  	{Opt_obsolete, "blocksize=%u"},
  	{Opt_obsolete, "cvf_format=%20s"},
  	{Opt_obsolete, "cvf_options=%100s"},
  	{Opt_obsolete, "posix"},

  	{Opt_err, NULL},

  };

  static const match_table_t msdos_tokens = {

  	{Opt_nodots, "nodots"},
  	{Opt_nodots, "dotsOK=no"},
  	{Opt_dots, "dots"},
  	{Opt_dots, "dotsOK=yes"},
  	{Opt_err, NULL}
  };

  static const match_table_t vfat_tokens = {

  	{Opt_charset, "iocharset=%s"},
  	{Opt_shortname_lower, "shortname=lower"},
  	{Opt_shortname_win95, "shortname=win95"},
  	{Opt_shortname_winnt, "shortname=winnt"},
  	{Opt_shortname_mixed, "shortname=mixed"},
  	{Opt_utf8_no, "utf8=0"},		/* 0 or no or false */
  	{Opt_utf8_no, "utf8=no"},
  	{Opt_utf8_no, "utf8=false"},
  	{Opt_utf8_yes, "utf8=1"},		/* empty or 1 or yes or true */
  	{Opt_utf8_yes, "utf8=yes"},
  	{Opt_utf8_yes, "utf8=true"},
  	{Opt_utf8_yes, "utf8"},
  	{Opt_uni_xl_no, "uni_xlate=0"},		/* 0 or no or false */
  	{Opt_uni_xl_no, "uni_xlate=no"},
  	{Opt_uni_xl_no, "uni_xlate=false"},
  	{Opt_uni_xl_yes, "uni_xlate=1"},	/* empty or 1 or yes or true */
  	{Opt_uni_xl_yes, "uni_xlate=yes"},
  	{Opt_uni_xl_yes, "uni_xlate=true"},
  	{Opt_uni_xl_yes, "uni_xlate"},
  	{Opt_nonumtail_no, "nonumtail=0"},	/* 0 or no or false */
  	{Opt_nonumtail_no, "nonumtail=no"},
  	{Opt_nonumtail_no, "nonumtail=false"},
  	{Opt_nonumtail_yes, "nonumtail=1"},	/* empty or 1 or yes or true */
  	{Opt_nonumtail_yes, "nonumtail=yes"},
  	{Opt_nonumtail_yes, "nonumtail=true"},
  	{Opt_nonumtail_yes, "nonumtail"},

  	{Opt_rodir, "rodir"},

  	{Opt_err, NULL}
  };

  static int parse_options(struct super_block *sb, char *options, int is_vfat,
  			 int silent, int *debug, struct fat_mount_options *opts)

  {
  	char *p;
  	substring_t args[MAX_OPT_ARGS];
  	int option;
  	char *iocharset;
  
  	opts->isvfat = is_vfat;

  	opts->fs_uid = current_uid();
  	opts->fs_gid = current_gid();

  	opts->fs_fmask = opts->fs_dmask = current_umask();

  	opts->allow_utime = -1;

  	opts->codepage = fat_default_codepage;

  	fat_reset_iocharset(opts);

  	if (is_vfat) {

  		opts->shortname = VFAT_SFN_DISPLAY_WINNT|VFAT_SFN_CREATE_WIN95;

  		opts->rodir = 0;
  	} else {

  		opts->shortname = 0;

  		opts->rodir = 1;
  	}

  	opts->name_check = 'n';
  	opts->quiet = opts->showexec = opts->sys_immutable = opts->dotsOK =  0;

  	opts->unicode_xlate = 0;

  	opts->numtail = 1;

  	opts->usefree = opts->nocase = 0;

  	opts->tz_set = 0;

  	opts->nfs = 0;

  	opts->errors = FAT_ERRORS_RO;

  	*debug = 0;

  	opts->utf8 = IS_ENABLED(CONFIG_FAT_DEFAULT_UTF8) && is_vfat;

  	if (!options)

  		goto out;

  
  	while ((p = strsep(&options, ",")) != NULL) {
  		int token;
  		if (!*p)
  			continue;
  
  		token = match_token(p, fat_tokens, args);
  		if (token == Opt_err) {
  			if (is_vfat)
  				token = match_token(p, vfat_tokens, args);
  			else
  				token = match_token(p, msdos_tokens, args);
  		}
  		switch (token) {
  		case Opt_check_s:
  			opts->name_check = 's';
  			break;
  		case Opt_check_r:
  			opts->name_check = 'r';
  			break;
  		case Opt_check_n:
  			opts->name_check = 'n';
  			break;

  		case Opt_usefree:
  			opts->usefree = 1;
  			break;

  		case Opt_nocase:
  			if (!is_vfat)
  				opts->nocase = 1;
  			else {
  				/* for backward compatibility */
  				opts->shortname = VFAT_SFN_DISPLAY_WIN95
  					| VFAT_SFN_CREATE_WIN95;
  			}
  			break;
  		case Opt_quiet:
  			opts->quiet = 1;
  			break;
  		case Opt_showexec:
  			opts->showexec = 1;
  			break;
  		case Opt_debug:
  			*debug = 1;
  			break;
  		case Opt_immutable:
  			opts->sys_immutable = 1;
  			break;
  		case Opt_uid:
  			if (match_int(&args[0], &option))

  				return -EINVAL;

  			opts->fs_uid = make_kuid(current_user_ns(), option);
  			if (!uid_valid(opts->fs_uid))

  				return -EINVAL;

  			break;
  		case Opt_gid:
  			if (match_int(&args[0], &option))

  				return -EINVAL;

  			opts->fs_gid = make_kgid(current_user_ns(), option);
  			if (!gid_valid(opts->fs_gid))

  				return -EINVAL;

  			break;
  		case Opt_umask:
  			if (match_octal(&args[0], &option))

  				return -EINVAL;

  			opts->fs_fmask = opts->fs_dmask = option;
  			break;
  		case Opt_dmask:
  			if (match_octal(&args[0], &option))

  				return -EINVAL;

  			opts->fs_dmask = option;
  			break;
  		case Opt_fmask:
  			if (match_octal(&args[0], &option))

  				return -EINVAL;

  			opts->fs_fmask = option;
  			break;

  		case Opt_allow_utime:
  			if (match_octal(&args[0], &option))

  				return -EINVAL;

  			opts->allow_utime = option & (S_IWGRP | S_IWOTH);
  			break;

  		case Opt_codepage:
  			if (match_int(&args[0], &option))

  				return -EINVAL;

  			opts->codepage = option;
  			break;

  		case Opt_flush:
  			opts->flush = 1;
  			break;

  		case Opt_time_offset:
  			if (match_int(&args[0], &option))

  				return -EINVAL;

  			/*
  			 * GMT+-12 zones may have DST corrections so at least
  			 * 13 hours difference is needed. Make the limit 24
  			 * just in case someone invents something unusual.
  			 */
  			if (option < -24 * 60 || option > 24 * 60)

  				return -EINVAL;

  			opts->tz_set = 1;
  			opts->time_offset = option;
  			break;

  		case Opt_tz_utc:

  			opts->tz_set = 1;
  			opts->time_offset = 0;

  			break;

  		case Opt_err_cont:
  			opts->errors = FAT_ERRORS_CONT;
  			break;
  		case Opt_err_panic:
  			opts->errors = FAT_ERRORS_PANIC;
  			break;
  		case Opt_err_ro:
  			opts->errors = FAT_ERRORS_RO;
  			break;

  		case Opt_nfs_stale_rw:
  			opts->nfs = FAT_NFS_STALE_RW;
  			break;
  		case Opt_nfs_nostale_ro:
  			opts->nfs = FAT_NFS_NOSTALE_RO;
  			break;

  		case Opt_dos1xfloppy:
  			opts->dos1xfloppy = 1;
  			break;

  
  		/* msdos specific */
  		case Opt_dots:
  			opts->dotsOK = 1;
  			break;
  		case Opt_nodots:
  			opts->dotsOK = 0;
  			break;
  
  		/* vfat specific */
  		case Opt_charset:

  			fat_reset_iocharset(opts);

  			iocharset = match_strdup(&args[0]);
  			if (!iocharset)
  				return -ENOMEM;
  			opts->iocharset = iocharset;
  			break;
  		case Opt_shortname_lower:
  			opts->shortname = VFAT_SFN_DISPLAY_LOWER
  					| VFAT_SFN_CREATE_WIN95;
  			break;
  		case Opt_shortname_win95:
  			opts->shortname = VFAT_SFN_DISPLAY_WIN95
  					| VFAT_SFN_CREATE_WIN95;
  			break;
  		case Opt_shortname_winnt:
  			opts->shortname = VFAT_SFN_DISPLAY_WINNT
  					| VFAT_SFN_CREATE_WINNT;
  			break;
  		case Opt_shortname_mixed:
  			opts->shortname = VFAT_SFN_DISPLAY_WINNT
  					| VFAT_SFN_CREATE_WIN95;
  			break;
  		case Opt_utf8_no:		/* 0 or no or false */
  			opts->utf8 = 0;
  			break;
  		case Opt_utf8_yes:		/* empty or 1 or yes or true */
  			opts->utf8 = 1;
  			break;
  		case Opt_uni_xl_no:		/* 0 or no or false */
  			opts->unicode_xlate = 0;
  			break;
  		case Opt_uni_xl_yes:		/* empty or 1 or yes or true */
  			opts->unicode_xlate = 1;
  			break;
  		case Opt_nonumtail_no:		/* 0 or no or false */
  			opts->numtail = 1;	/* negated option */
  			break;
  		case Opt_nonumtail_yes:		/* empty or 1 or yes or true */
  			opts->numtail = 0;	/* negated option */
  			break;

  		case Opt_rodir:
  			opts->rodir = 1;
  			break;

  		case Opt_discard:
  			opts->discard = 1;
  			break;

  
  		/* obsolete mount options */

  		case Opt_obsolete:

  			fat_msg(sb, KERN_INFO, "\"%s\" option is obsolete, "
  			       "not supported now", p);

  			break;
  		/* unknown option */
  		default:

  			if (!silent) {

  				fat_msg(sb, KERN_ERR,
  				       "Unrecognized mount option \"%s\" "
  				       "or missing value", p);

  			}

  			return -EINVAL;
  		}
  	}

  
  out:

  	/* UTF-8 doesn't provide FAT semantics */

  	if (!strcmp(opts->iocharset, "utf8")) {

  		fat_msg(sb, KERN_WARNING, "utf8 is not a recommended IO charset"

  		       " for FAT filesystems, filesystem will be "

  		       "case sensitive!");

  	}

  	/* If user doesn't specify allow_utime, it's initialized from dmask. */
  	if (opts->allow_utime == (unsigned short)-1)
  		opts->allow_utime = ~opts->fs_dmask & (S_IWGRP | S_IWOTH);

  	if (opts->unicode_xlate)
  		opts->utf8 = 0;

  	if (opts->nfs == FAT_NFS_NOSTALE_RO) {

  		sb->s_flags |= SB_RDONLY;

  		sb->s_export_op = &fat_export_ops_nostale;
  	}

  
  	return 0;
  }
  
  static int fat_read_root(struct inode *inode)
  {

  	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);

  	int error;

  	MSDOS_I(inode)->i_pos = MSDOS_ROOT_INO;

  	inode->i_uid = sbi->options.fs_uid;
  	inode->i_gid = sbi->options.fs_gid;

  	inode_inc_iversion(inode);

  	inode->i_generation = 0;

  	inode->i_mode = fat_make_mode(sbi, ATTR_DIR, S_IRWXUGO);

  	inode->i_op = sbi->dir_ops;
  	inode->i_fop = &fat_dir_operations;

  	if (is_fat32(sbi)) {

  		MSDOS_I(inode)->i_start = sbi->root_cluster;
  		error = fat_calc_dir_size(inode);
  		if (error < 0)
  			return error;
  	} else {
  		MSDOS_I(inode)->i_start = 0;
  		inode->i_size = sbi->dir_entries * sizeof(struct msdos_dir_entry);
  	}

  	inode->i_blocks = ((inode->i_size + (sbi->cluster_size - 1))
  			   & ~((loff_t)sbi->cluster_size - 1)) >> 9;
  	MSDOS_I(inode)->i_logstart = 0;
  	MSDOS_I(inode)->mmu_private = inode->i_size;

  	fat_save_attrs(inode, ATTR_DIR);

  	inode->i_mtime.tv_sec = inode->i_atime.tv_sec = inode->i_ctime.tv_sec = 0;
  	inode->i_mtime.tv_nsec = inode->i_atime.tv_nsec = inode->i_ctime.tv_nsec = 0;

  	set_nlink(inode, fat_subdirs(inode)+2);

  
  	return 0;
  }

  static unsigned long calc_fat_clusters(struct super_block *sb)
  {
  	struct msdos_sb_info *sbi = MSDOS_SB(sb);
  
  	/* Divide first to avoid overflow */

  	if (!is_fat12(sbi)) {

  		unsigned long ent_per_sec = sb->s_blocksize * 8 / sbi->fat_bits;
  		return ent_per_sec * sbi->fat_length;
  	}
  
  	return sbi->fat_length * sb->s_blocksize * 8 / sbi->fat_bits;
  }

  static bool fat_bpb_is_zero(struct fat_boot_sector *b)
  {
  	if (get_unaligned_le16(&b->sector_size))
  		return false;
  	if (b->sec_per_clus)
  		return false;
  	if (b->reserved)
  		return false;
  	if (b->fats)
  		return false;
  	if (get_unaligned_le16(&b->dir_entries))
  		return false;
  	if (get_unaligned_le16(&b->sectors))
  		return false;
  	if (b->media)
  		return false;
  	if (b->fat_length)
  		return false;
  	if (b->secs_track)
  		return false;
  	if (b->heads)
  		return false;
  	return true;
  }
  
  static int fat_read_bpb(struct super_block *sb, struct fat_boot_sector *b,
  	int silent, struct fat_bios_param_block *bpb)
  {
  	int error = -EINVAL;
  
  	/* Read in BPB ... */
  	memset(bpb, 0, sizeof(*bpb));
  	bpb->fat_sector_size = get_unaligned_le16(&b->sector_size);
  	bpb->fat_sec_per_clus = b->sec_per_clus;
  	bpb->fat_reserved = le16_to_cpu(b->reserved);
  	bpb->fat_fats = b->fats;
  	bpb->fat_dir_entries = get_unaligned_le16(&b->dir_entries);
  	bpb->fat_sectors = get_unaligned_le16(&b->sectors);
  	bpb->fat_fat_length = le16_to_cpu(b->fat_length);
  	bpb->fat_total_sect = le32_to_cpu(b->total_sect);
  
  	bpb->fat16_state = b->fat16.state;
  	bpb->fat16_vol_id = get_unaligned_le32(b->fat16.vol_id);
  
  	bpb->fat32_length = le32_to_cpu(b->fat32.length);
  	bpb->fat32_root_cluster = le32_to_cpu(b->fat32.root_cluster);
  	bpb->fat32_info_sector = le16_to_cpu(b->fat32.info_sector);
  	bpb->fat32_state = b->fat32.state;
  	bpb->fat32_vol_id = get_unaligned_le32(b->fat32.vol_id);
  
  	/* Validate this looks like a FAT filesystem BPB */
  	if (!bpb->fat_reserved) {
  		if (!silent)
  			fat_msg(sb, KERN_ERR,
  				"bogus number of reserved sectors");
  		goto out;
  	}
  	if (!bpb->fat_fats) {
  		if (!silent)
  			fat_msg(sb, KERN_ERR, "bogus number of FAT structure");
  		goto out;
  	}
  
  	/*
  	 * Earlier we checked here that b->secs_track and b->head are nonzero,
  	 * but it turns out valid FAT filesystems can have zero there.
  	 */
  
  	if (!fat_valid_media(b->media)) {
  		if (!silent)
  			fat_msg(sb, KERN_ERR, "invalid media value (0x%02x)",
  				(unsigned)b->media);
  		goto out;
  	}
  
  	if (!is_power_of_2(bpb->fat_sector_size)
  	    || (bpb->fat_sector_size < 512)
  	    || (bpb->fat_sector_size > 4096)) {
  		if (!silent)
  			fat_msg(sb, KERN_ERR, "bogus logical sector size %u",
  			       (unsigned)bpb->fat_sector_size);
  		goto out;
  	}
  
  	if (!is_power_of_2(bpb->fat_sec_per_clus)) {
  		if (!silent)
  			fat_msg(sb, KERN_ERR, "bogus sectors per cluster %u",
  				(unsigned)bpb->fat_sec_per_clus);
  		goto out;
  	}

  	if (bpb->fat_fat_length == 0 && bpb->fat32_length == 0) {
  		if (!silent)
  			fat_msg(sb, KERN_ERR, "bogus number of FAT sectors");
  		goto out;
  	}

  	error = 0;
  
  out:
  	return error;
  }
  
  static int fat_read_static_bpb(struct super_block *sb,
  	struct fat_boot_sector *b, int silent,
  	struct fat_bios_param_block *bpb)
  {
  	static const char *notdos1x = "This doesn't look like a DOS 1.x volume";
  
  	struct fat_floppy_defaults *fdefaults = NULL;
  	int error = -EINVAL;
  	sector_t bd_sects;
  	unsigned i;
  
  	bd_sects = i_size_read(sb->s_bdev->bd_inode) / SECTOR_SIZE;
  
  	/* 16-bit DOS 1.x reliably wrote bootstrap short-jmp code */
  	if (b->ignored[0] != 0xeb || b->ignored[2] != 0x90) {
  		if (!silent)
  			fat_msg(sb, KERN_ERR,
  				"%s; no bootstrapping code", notdos1x);
  		goto out;
  	}
  
  	/*
  	 * If any value in this region is non-zero, it isn't archaic
  	 * DOS.
  	 */
  	if (!fat_bpb_is_zero(b)) {
  		if (!silent)
  			fat_msg(sb, KERN_ERR,
  				"%s; DOS 2.x BPB is non-zero", notdos1x);
  		goto out;
  	}
  
  	for (i = 0; i < ARRAY_SIZE(floppy_defaults); i++) {
  		if (floppy_defaults[i].nr_sectors == bd_sects) {
  			fdefaults = &floppy_defaults[i];
  			break;
  		}
  	}
  
  	if (fdefaults == NULL) {
  		if (!silent)
  			fat_msg(sb, KERN_WARNING,
  				"This looks like a DOS 1.x volume, but isn't a recognized floppy size (%llu sectors)",
  				(u64)bd_sects);
  		goto out;
  	}
  
  	if (!silent)
  		fat_msg(sb, KERN_INFO,
  			"This looks like a DOS 1.x volume; assuming default BPB values");
  
  	memset(bpb, 0, sizeof(*bpb));
  	bpb->fat_sector_size = SECTOR_SIZE;
  	bpb->fat_sec_per_clus = fdefaults->sec_per_clus;
  	bpb->fat_reserved = 1;
  	bpb->fat_fats = 2;
  	bpb->fat_dir_entries = fdefaults->dir_entries;
  	bpb->fat_sectors = fdefaults->nr_sectors;
  	bpb->fat_fat_length = fdefaults->fat_length;
  
  	error = 0;
  
  out:
  	return error;
  }

  /*
   * Read the super block of an MS-DOS FS.
   */

  int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat,

  		   void (*setup)(struct super_block *))

  {

  	struct inode *root_inode = NULL, *fat_inode = NULL;

  	struct inode *fsinfo_inode = NULL;

  	struct buffer_head *bh;

  	struct fat_bios_param_block bpb;

  	struct msdos_sb_info *sbi;
  	u16 logical_sector_size;
  	u32 total_sectors, total_clusters, fat_clusters, rootdir_sectors;
  	int debug;

  	long error;
  	char buf[50];

  	struct timespec64 ts;

  	/*
  	 * GFP_KERNEL is ok here, because while we do hold the

  	 * superblock lock, memory pressure can't call back into

  	 * the filesystem, since we're only just about to mount
  	 * it and have no inodes etc active!
  	 */

  	sbi = kzalloc(sizeof(struct msdos_sb_info), GFP_KERNEL);

  	if (!sbi)
  		return -ENOMEM;
  	sb->s_fs_info = sbi;

  	sb->s_flags |= SB_NODIRATIME;

  	sb->s_magic = MSDOS_SUPER_MAGIC;
  	sb->s_op = &fat_sops;
  	sb->s_export_op = &fat_export_ops;

  	/*
  	 * fat timestamps are complex and truncated by fat itself, so
  	 * we set 1 here to be fast
  	 */
  	sb->s_time_gran = 1;

  	mutex_init(&sbi->nfs_build_inode_lock);

  	ratelimit_state_init(&sbi->ratelimit, DEFAULT_RATELIMIT_INTERVAL,
  			     DEFAULT_RATELIMIT_BURST);

  	error = parse_options(sb, data, isvfat, silent, &debug, &sbi->options);

  	if (error)
  		goto out_fail;

  	setup(sb); /* flavour-specific stuff that needs options */

  	error = -EIO;
  	sb_min_blocksize(sb, 512);
  	bh = sb_bread(sb, 0);
  	if (bh == NULL) {

  		fat_msg(sb, KERN_ERR, "unable to read boot sector");

  		goto out_fail;
  	}

  	error = fat_read_bpb(sb, (struct fat_boot_sector *)bh->b_data, silent,
  		&bpb);
  	if (error == -EINVAL && sbi->options.dos1xfloppy)
  		error = fat_read_static_bpb(sb,
  			(struct fat_boot_sector *)bh->b_data, silent, &bpb);
  	brelse(bh);

  	if (error == -EINVAL)

  		goto out_invalid;

  	else if (error)
  		goto out_fail;

  	logical_sector_size = bpb.fat_sector_size;
  	sbi->sec_per_clus = bpb.fat_sec_per_clus;
  
  	error = -EIO;

  	if (logical_sector_size < sb->s_blocksize) {

  		fat_msg(sb, KERN_ERR, "logical sector size too small for device"
  		       " (logical sector size = %u)", logical_sector_size);

  		goto out_fail;
  	}

  	if (logical_sector_size > sb->s_blocksize) {

  		struct buffer_head *bh_resize;

  
  		if (!sb_set_blocksize(sb, logical_sector_size)) {

  			fat_msg(sb, KERN_ERR, "unable to set blocksize %u",

  			       logical_sector_size);
  			goto out_fail;
  		}

  
  		/* Verify that the larger boot sector is fully readable */
  		bh_resize = sb_bread(sb, 0);
  		if (bh_resize == NULL) {

  			fat_msg(sb, KERN_ERR, "unable to read boot sector"
  			       " (logical sector size = %lu)",

  			       sb->s_blocksize);
  			goto out_fail;
  		}

  		brelse(bh_resize);

  	}

  	mutex_init(&sbi->s_lock);

  	sbi->cluster_size = sb->s_blocksize * sbi->sec_per_clus;
  	sbi->cluster_bits = ffs(sbi->cluster_size) - 1;

  	sbi->fats = bpb.fat_fats;

  	sbi->fat_bits = 0;		/* Don't know yet */

  	sbi->fat_start = bpb.fat_reserved;
  	sbi->fat_length = bpb.fat_fat_length;

  	sbi->root_cluster = 0;
  	sbi->free_clusters = -1;	/* Don't know yet */

  	sbi->free_clus_valid = 0;

  	sbi->prev_free = FAT_START_ENT;

  	sb->s_maxbytes = 0xffffffff;

  	fat_time_fat2unix(sbi, &ts, 0, cpu_to_le16(FAT_DATE_MIN), 0);
  	sb->s_time_min = ts.tv_sec;
  
  	fat_time_fat2unix(sbi, &ts, cpu_to_le16(FAT_TIME_MAX),
  			  cpu_to_le16(FAT_DATE_MAX), 0);
  	sb->s_time_max = ts.tv_sec;

  	if (!sbi->fat_length && bpb.fat32_length) {

  		struct fat_boot_fsinfo *fsinfo;
  		struct buffer_head *fsinfo_bh;
  
  		/* Must be FAT32 */
  		sbi->fat_bits = 32;

  		sbi->fat_length = bpb.fat32_length;
  		sbi->root_cluster = bpb.fat32_root_cluster;

  		/* MC - if info_sector is 0, don't multiply by 0 */

  		sbi->fsinfo_sector = bpb.fat32_info_sector;

  		if (sbi->fsinfo_sector == 0)
  			sbi->fsinfo_sector = 1;
  
  		fsinfo_bh = sb_bread(sb, sbi->fsinfo_sector);
  		if (fsinfo_bh == NULL) {

  			fat_msg(sb, KERN_ERR, "bread failed, FSINFO block"
  			       " (sector = %lu)", sbi->fsinfo_sector);

  			goto out_fail;
  		}
  
  		fsinfo = (struct fat_boot_fsinfo *)fsinfo_bh->b_data;
  		if (!IS_FSINFO(fsinfo)) {

  			fat_msg(sb, KERN_WARNING, "Invalid FSINFO signature: "
  			       "0x%08x, 0x%08x (sector = %lu)",

  			       le32_to_cpu(fsinfo->signature1),
  			       le32_to_cpu(fsinfo->signature2),
  			       sbi->fsinfo_sector);
  		} else {

  			if (sbi->options.usefree)

  				sbi->free_clus_valid = 1;
  			sbi->free_clusters = le32_to_cpu(fsinfo->free_clusters);

  			sbi->prev_free = le32_to_cpu(fsinfo->next_cluster);
  		}
  
  		brelse(fsinfo_bh);
  	}

  	/* interpret volume ID as a little endian 32 bit integer */

  	if (is_fat32(sbi))

  		sbi->vol_id = bpb.fat32_vol_id;

  	else /* fat 16 or 12 */

  		sbi->vol_id = bpb.fat16_vol_id;

  	sbi->dir_per_block = sb->s_blocksize / sizeof(struct msdos_dir_entry);
  	sbi->dir_per_block_bits = ffs(sbi->dir_per_block) - 1;
  
  	sbi->dir_start = sbi->fat_start + sbi->fats * sbi->fat_length;

  	sbi->dir_entries = bpb.fat_dir_entries;

  	if (sbi->dir_entries & (sbi->dir_per_block - 1)) {
  		if (!silent)

  			fat_msg(sb, KERN_ERR, "bogus number of directory entries"

  			       " (%u)", sbi->dir_entries);

  		goto out_invalid;
  	}
  
  	rootdir_sectors = sbi->dir_entries
  		* sizeof(struct msdos_dir_entry) / sb->s_blocksize;
  	sbi->data_start = sbi->dir_start + rootdir_sectors;

  	total_sectors = bpb.fat_sectors;

  	if (total_sectors == 0)

  		total_sectors = bpb.fat_total_sect;

  
  	total_clusters = (total_sectors - sbi->data_start) / sbi->sec_per_clus;

  	if (!is_fat32(sbi))

  		sbi->fat_bits = (total_clusters > MAX_FAT12) ? 16 : 12;

  	/* some OSes set FAT_STATE_DIRTY and clean it on unmount. */

  	if (is_fat32(sbi))

  		sbi->dirty = bpb.fat32_state & FAT_STATE_DIRTY;

  	else /* fat 16 or 12 */

  		sbi->dirty = bpb.fat16_state & FAT_STATE_DIRTY;

  	/* check that FAT table does not overflow */

  	fat_clusters = calc_fat_clusters(sb);

  	total_clusters = min(total_clusters, fat_clusters - FAT_START_ENT);

  	if (total_clusters > max_fat(sb)) {

  		if (!silent)

  			fat_msg(sb, KERN_ERR, "count of clusters too big (%u)",

  			       total_clusters);

  		goto out_invalid;
  	}
  
  	sbi->max_cluster = total_clusters + FAT_START_ENT;
  	/* check the free_clusters, it's not necessarily correct */
  	if (sbi->free_clusters != -1 && sbi->free_clusters > total_clusters)
  		sbi->free_clusters = -1;
  	/* check the prev_free, it's not necessarily correct */
  	sbi->prev_free %= sbi->max_cluster;
  	if (sbi->prev_free < FAT_START_ENT)
  		sbi->prev_free = FAT_START_ENT;

  	/* set up enough so that it can read an inode */
  	fat_hash_init(sb);

  	dir_hash_init(sb);

  	fat_ent_access_init(sb);
  
  	/*

  	 * The low byte of the first FAT entry must have the same value as
  	 * the media field of the boot sector. But in real world, too many
  	 * devices are writing wrong values. So, removed that validity check.

  	 *

  	 * The removed check compared the first FAT entry to a value dependent
  	 * on the media field like this:
  	 * == (0x0F00 | media), for FAT12
  	 * == (0XFF00 | media), for FAT16
  	 * == (0x0FFFFF | media), for FAT32

  	 */
  
  	error = -EINVAL;
  	sprintf(buf, "cp%d", sbi->options.codepage);
  	sbi->nls_disk = load_nls(buf);
  	if (!sbi->nls_disk) {

  		fat_msg(sb, KERN_ERR, "codepage %s not found", buf);

  		goto out_fail;
  	}
  
  	/* FIXME: utf8 is using iocharset for upper/lower conversion */
  	if (sbi->options.isvfat) {
  		sbi->nls_io = load_nls(sbi->options.iocharset);
  		if (!sbi->nls_io) {

  			fat_msg(sb, KERN_ERR, "IO charset %s not found",

  			       sbi->options.iocharset);
  			goto out_fail;
  		}
  	}
  
  	error = -ENOMEM;

  	fat_inode = new_inode(sb);
  	if (!fat_inode)
  		goto out_fail;

  	sbi->fat_inode = fat_inode;

  
  	fsinfo_inode = new_inode(sb);
  	if (!fsinfo_inode)
  		goto out_fail;
  	fsinfo_inode->i_ino = MSDOS_FSINFO_INO;
  	sbi->fsinfo_inode = fsinfo_inode;
  	insert_inode_hash(fsinfo_inode);

  	root_inode = new_inode(sb);
  	if (!root_inode)
  		goto out_fail;
  	root_inode->i_ino = MSDOS_ROOT_INO;

  	inode_set_iversion(root_inode, 1);

  	error = fat_read_root(root_inode);

  	if (error < 0) {
  		iput(root_inode);

  		goto out_fail;

  	}

  	error = -ENOMEM;
  	insert_inode_hash(root_inode);

  	fat_attach(root_inode, 0);

  	sb->s_root = d_make_root(root_inode);

  	if (!sb->s_root) {

  		fat_msg(sb, KERN_ERR, "get root inode failed");

  		goto out_fail;
  	}

  	if (sbi->options.discard) {
  		struct request_queue *q = bdev_get_queue(sb->s_bdev);
  		if (!blk_queue_discard(q))
  			fat_msg(sb, KERN_WARNING,
  					"mounting with \"discard\" option, but "
  					"the device does not support discard");
  	}

  	fat_set_state(sb, 1, 0);

  	return 0;
  
  out_invalid:
  	error = -EINVAL;
  	if (!silent)

  		fat_msg(sb, KERN_INFO, "Can't find a valid FAT filesystem");

  
  out_fail:

  	if (fsinfo_inode)
  		iput(fsinfo_inode);

  	if (fat_inode)
  		iput(fat_inode);

  	unload_nls(sbi->nls_io);
  	unload_nls(sbi->nls_disk);

  	fat_reset_iocharset(&sbi->options);

  	sb->s_fs_info = NULL;
  	kfree(sbi);
  	return error;
  }

  EXPORT_SYMBOL_GPL(fat_fill_super);

  /*
   * helper function for fat_flush_inodes.  This writes both the inode
   * and the file data blocks, waiting for in flight data blocks before
   * the start of the call.  It does not wait for any io started
   * during the call
   */
  static int writeback_inode(struct inode *inode)
  {
  
  	int ret;

  
  	/* if we used wait=1, sync_inode_metadata waits for the io for the
  	* inode to finish.  So wait=0 is sent down to sync_inode_metadata

  	* and filemap_fdatawrite is used for the data blocks
  	*/

  	ret = sync_inode_metadata(inode, 0);

  	if (!ret)

  		ret = filemap_fdatawrite(inode->i_mapping);

  	return ret;
  }
  
  /*
   * write data and metadata corresponding to i1 and i2.  The io is
   * started but we do not wait for any of it to finish.
   *
   * filemap_flush is used for the block device, so if there is a dirty
   * page for a block already in flight, we will not wait and start the
   * io over again
   */
  int fat_flush_inodes(struct super_block *sb, struct inode *i1, struct inode *i2)
  {
  	int ret = 0;
  	if (!MSDOS_SB(sb)->options.flush)
  		return 0;
  	if (i1)
  		ret = writeback_inode(i1);
  	if (!ret && i2)
  		ret = writeback_inode(i2);

  	if (!ret) {

  		struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping;
  		ret = filemap_flush(mapping);
  	}
  	return ret;
  }
  EXPORT_SYMBOL_GPL(fat_flush_inodes);

  static int __init init_fat_fs(void)
  {

  	int err;

  	err = fat_cache_init();
  	if (err)
  		return err;
  
  	err = fat_init_inodecache();
  	if (err)
  		goto failed;
  
  	return 0;
  
  failed:
  	fat_cache_destroy();
  	return err;

  }
  
  static void __exit exit_fat_fs(void)
  {
  	fat_cache_destroy();
  	fat_destroy_inodecache();
  }
  
  module_init(init_fat_fs)
  module_exit(exit_fat_fs)
  
  MODULE_LICENSE("GPL");