/*
 *  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/version.h>
#define __NO_VERSION__
#include <linux/module.h>

#include <linux/msdos_fs.h>
#include <linux/nls.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/major.h>
#include <linux/blkdev.h>
#include <linux/fs.h>
#include <linux/stat.h>
#include <linux/locks.h>
#include <linux/fat_cvf.h>
#include <linux/malloc.h>

#include "msbuffer.h"

#include <asm/uaccess.h>
#include <asm/unaligned.h>

/* #define FAT_PARANOIA 1 */
#define DEBUG_LEVEL 0
#ifdef FAT_DEBUG
#  define PRINTK(x) printk x
#else
#  define PRINTK(x)
#endif
#if (DEBUG_LEVEL >= 1)
#  define PRINTK1(x) printk x
#else
#  define PRINTK1(x)
#endif

/*
 * 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_clear_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.
 */

#define FAT_HASH_BITS	8
#define FAT_HASH_SIZE	(1UL << FAT_HASH_BITS)
#define FAT_HASH_MASK	(FAT_HASH_SIZE-1)
static struct list_head fat_inode_hashtable[FAT_HASH_SIZE];
spinlock_t fat_inode_lock = SPIN_LOCK_UNLOCKED;

void fat_hash_init(void) {
	int i;
	for(i=0;i<FAT_HASH_SIZE;i++) {
		INIT_LIST_HEAD(&fat_inode_hashtable[i]);
	}
}

static inline unsigned long fat_hash(struct super_block *sb, int i_pos)
{
	unsigned long tmp = (unsigned long)i_pos | (unsigned long) sb;
	tmp = tmp + (tmp >> FAT_HASH_BITS) + (tmp >> FAT_HASH_BITS*2);
	return tmp & FAT_HASH_MASK;
}

void fat_attach(struct inode *inode, int i_pos) {
	spin_lock(&fat_inode_lock);
	MSDOS_I(inode)->i_location = i_pos;
	list_add(&MSDOS_I(inode)->i_fat_hash,
		fat_inode_hashtable+fat_hash(inode->i_sb, i_pos));
	spin_unlock(&fat_inode_lock);
}

void fat_detach(struct inode *inode) {
	spin_lock(&fat_inode_lock);
	MSDOS_I(inode)->i_location = 0;
	list_del(&MSDOS_I(inode)->i_fat_hash);
	INIT_LIST_HEAD(&MSDOS_I(inode)->i_fat_hash);
	spin_unlock(&fat_inode_lock);
}

struct inode *fat_iget(struct super_block *sb, int i_pos) {
	struct list_head *p = fat_inode_hashtable + fat_hash(sb, i_pos);
	struct list_head *walk;
	struct msdos_inode_info *i;
	struct inode *inode = NULL;
	spin_lock(&fat_inode_lock);
	for(walk=p->next;walk!=p;walk=walk->next) {
		i = list_entry(walk, struct msdos_inode_info, i_fat_hash);
		if (i->i_fat_inode->i_sb != sb)
			continue;
		if (i->i_location != i_pos)
			continue;
		inode = igrab(i->i_fat_inode);
	}
	spin_unlock(&fat_inode_lock);
	return inode;
}

static void fat_fill_inode(struct inode *inode, struct msdos_dir_entry *de);

struct inode *fat_build_inode(struct super_block *sb,
				struct msdos_dir_entry *de, int ino, int *res)
{
	struct inode *inode;
	*res = 0;
	inode = fat_iget(sb, ino);
	if (inode)
		goto out;
	inode = get_empty_inode();
	*res = -ENOMEM;
	if (!inode)
		goto out;
	*res = 0;
	inode->i_sb = sb;
	inode->i_dev = sb->s_dev;
	inode->i_ino = iunique(sb, MSDOS_ROOT_INO);
	fat_fill_inode(inode, de);
	fat_attach(inode, ino);
	insert_inode_hash(inode);
out:
	return inode;
}

void fat_delete_inode(struct inode *inode)
{
	inode->i_size = 0;
	fat_truncate(inode);
	clear_inode(inode);
}

void fat_clear_inode(struct inode *inode)
{
	spin_lock(&fat_inode_lock);
	fat_cache_inval_inode(inode);
	list_del(&MSDOS_I(inode)->i_fat_hash);
	spin_unlock(&fat_inode_lock);
}

void fat_put_super(struct super_block *sb)
{
	if (MSDOS_SB(sb)->cvf_format) {
		dec_cvf_format_use_count_by_version(MSDOS_SB(sb)->cvf_format->cvf_version);
		MSDOS_SB(sb)->cvf_format->unmount_cvf(sb);
	}
	if (MSDOS_SB(sb)->fat_bits == 32) {
		fat_clusters_flush(sb);
	}
	fat_cache_inval_dev(sb->s_dev);
	set_blocksize (sb->s_dev,BLOCK_SIZE);
	if (MSDOS_SB(sb)->nls_disk) {
		unload_nls(MSDOS_SB(sb)->nls_disk);
		MSDOS_SB(sb)->nls_disk = NULL;
		MSDOS_SB(sb)->options.codepage = 0;
	}
	if (MSDOS_SB(sb)->nls_io) {
		unload_nls(MSDOS_SB(sb)->nls_io);
		MSDOS_SB(sb)->nls_io = NULL;
	}
	/*
	 * Note: the iocharset option might have been specified
	 * without enabling nls_io, so check for it here.
	 */
	if (MSDOS_SB(sb)->options.iocharset) {
		kfree(MSDOS_SB(sb)->options.iocharset);
		MSDOS_SB(sb)->options.iocharset = NULL;
	}

	if (MSDOS_SB(sb)->put_super_callback)
		MSDOS_SB(sb)->put_super_callback(sb);
	MOD_DEC_USE_COUNT;
	return;
}


static int parse_options(char *options,int *fat, int *blksize, int *debug,
			 struct fat_mount_options *opts,
			 char *cvf_format, char *cvf_options)
{
	char *this_char,*value,save,*savep;
	char *p;
	int ret = 1, len;

	opts->name_check = 'n';
	opts->conversion = 'b';
	opts->fs_uid = current->uid;
	opts->fs_gid = current->gid;
	opts->fs_umask = current->fs->umask;
	opts->quiet = opts->sys_immutable = opts->dotsOK = opts->showexec = 0;
	opts->codepage = 0;
	opts->utf8 = 0;
	opts->small_letter = 0;
	opts->iocharset = NULL;
	*debug = *fat = 0;

	if (!options)
		goto out;
	save = 0;
	savep = NULL;
	for (this_char = strtok(options,","); this_char;
	     this_char = strtok(NULL,",")) {
		if ((value = strchr(this_char,'=')) != NULL) {
			save = *value;
			savep = value;
			*value++ = 0;
		}
		if (!strcmp(this_char,"check") && value) {
			if (value[0] && !value[1] && strchr("rns",*value))
				opts->name_check = *value;
			else if (!strcmp(value,"relaxed"))
				opts->name_check = 'r';
			else if (!strcmp(value,"normal"))
				opts->name_check = 'n';
			else if (!strcmp(value,"strict"))
				opts->name_check = 's';
			else ret = 0;
		}
		else if (!strcmp(this_char,"conv") && value) {
			if (value[0] && !value[1] && strchr("bta",*value))
				opts->conversion = *value;
			else if (!strcmp(value,"binary"))
				opts->conversion = 'b';
			else if (!strcmp(value,"text"))
				opts->conversion = 't';
			else if (!strcmp(value,"auto"))
				opts->conversion = 'a';
			else ret = 0;
		}
		else if (!strcmp(this_char,"dots")) {
			opts->dotsOK = 1;
		}
		else if (!strcmp(this_char,"nodots")) {
			opts->dotsOK = 0;
		}
		else if (!strcmp(this_char,"showexec")) {
			opts->showexec = 1;
		}
		else if (!strcmp(this_char,"small")) {
			opts->small_letter = 1;
		}
		else if (!strcmp(this_char,"dotsOK") && value) {
			if (!strcmp(value,"yes")) opts->dotsOK = 1;
			else if (!strcmp(value,"no")) opts->dotsOK = 0;
			else ret = 0;
		}
		else if (!strcmp(this_char,"uid")) {
			if (!value || !*value) ret = 0;
			else {
				opts->fs_uid = simple_strtoul(value,&value,0);
				if (*value) ret = 0;
			}
		}
		else if (!strcmp(this_char,"gid")) {
			if (!value || !*value) ret= 0;
			else {
				opts->fs_gid = simple_strtoul(value,&value,0);
				if (*value) ret = 0;
			}
		}
		else if (!strcmp(this_char,"umask")) {
			if (!value || !*value) ret = 0;
			else {
				opts->fs_umask = simple_strtoul(value,&value,8);
				if (*value) ret = 0;
			}
		}
		else if (!strcmp(this_char,"debug")) {
			if (value) ret = 0;
			else *debug = 1;
		}
		else if (!strcmp(this_char,"fat")) {
			if (!value || !*value) ret = 0;
			else {
				*fat = simple_strtoul(value,&value,0);
				if (*value || (*fat != 12 && *fat != 16 &&
					       *fat != 32)) 
					ret = 0;
			}
		}
		else if (!strcmp(this_char,"quiet")) {
			if (value) ret = 0;
			else opts->quiet = 1;
		}
		else if (!strcmp(this_char,"blocksize")) {
			if (!value || !*value) ret = 0;
			else {
				*blksize = simple_strtoul(value,&value,0);
				if (*value || (*blksize != 512 &&
					*blksize != 1024 && *blksize != 2048))
					ret = 0;
			}
		}
		else if (!strcmp(this_char,"sys_immutable")) {
			if (value) ret = 0;
			else opts->sys_immutable = 1;
		}
		else if (!strcmp(this_char,"codepage") && value) {
			opts->codepage = simple_strtoul(value,&value,0);
			if (*value) ret = 0;
			else printk ("MSDOS FS: Using codepage %d\n",
					opts->codepage);
		}
		else if (!strcmp(this_char,"iocharset") && value) {
			p = value;
			while (*value && *value != ',') value++;
			len = value - p;
			if (len) { 
				char * buffer = kmalloc(len+1, GFP_KERNEL);
				if (buffer) {
					opts->iocharset = buffer;
					memcpy(buffer, p, len);
					buffer[len] = 0;
					printk("MSDOS FS: IO charset %s\n",
						buffer);
				} else
					ret = 0;
			}
		}
		else if (!strcmp(this_char,"cvf_format")) {
			if (!value)
				return 0;
			strncpy(cvf_format,value,20);
		}
		else if (!strcmp(this_char,"cvf_options")) {
			if (!value)
				return 0;
			strncpy(cvf_options,value,100);
		}

		if (this_char != options) *(this_char-1) = ',';
		if (value) *savep = save;
		if (ret == 0)
			break;
	}
out:
	return ret;
}

static void fat_read_root(struct inode *inode)
{
	struct super_block *sb = inode->i_sb;
	int nr;

	MSDOS_I(inode)->i_binary = 1;
	INIT_LIST_HEAD(&MSDOS_I(inode)->i_fat_hash);
	MSDOS_I(inode)->i_location = 0;
	MSDOS_I(inode)->i_fat_inode = inode;
	inode->i_uid = MSDOS_SB(sb)->options.fs_uid;
	inode->i_gid = MSDOS_SB(sb)->options.fs_gid;
	inode->i_version = ++global_event;
	MSDOS_I(inode)->i_last_pos = 0;
	inode->i_mode = (S_IRWXUGO & ~MSDOS_SB(sb)->options.fs_umask) | S_IFDIR;
	inode->i_op = MSDOS_SB(sb)->dir_ops;
	if (MSDOS_SB(sb)->fat_bits == 32) {
		MSDOS_I(inode)->i_start = MSDOS_SB(sb)->root_cluster;
		if ((nr = MSDOS_I(inode)->i_start) != 0) {
			while (nr != -1) {
				inode->i_size += SECTOR_SIZE*MSDOS_SB(sb)->cluster_size;
				if (!(nr = fat_access(sb,nr,-1))) {
					printk("Directory %ld: bad FAT\n",
					       inode->i_ino);
					break;
				}
			}
		}
	} else {
		MSDOS_I(inode)->i_start = 0;
		inode->i_size = MSDOS_SB(sb)->dir_entries*
			sizeof(struct msdos_dir_entry);
	}
	inode->i_blksize = MSDOS_SB(sb)->cluster_size* SECTOR_SIZE;
	inode->i_blocks = (inode->i_size+inode->i_blksize-1)/
		    inode->i_blksize*MSDOS_SB(sb)->cluster_size;
	MSDOS_I(inode)->i_logstart = 0;

	MSDOS_I(inode)->i_attrs = 0;
	inode->i_mtime = inode->i_atime = inode->i_ctime = 0;
	MSDOS_I(inode)->i_ctime_ms = 0;
	inode->i_nlink = fat_subdirs(inode)+2;
}

static struct super_operations fat_sops = { 
	NULL,
	fat_write_inode,
	NULL,
	fat_delete_inode,
	fat_notify_change,
	fat_put_super,
	NULL,		/* write_super */
	fat_statfs,
	NULL,		/* remount */
	fat_clear_inode
};

/*
 * Read the super block of an MS-DOS FS.
 *
 * Note that this may be called from vfat_read_super
 * with some fields already initialized.
 */
struct super_block *
fat_read_super(struct super_block *sb, void *data, int silent,
		struct inode_operations *fs_dir_inode_ops)
{
	struct inode *root_inode;
	struct buffer_head *bh;
	struct fat_boot_sector *b;
	char *p;
	int data_sectors,logical_sector_size,sector_mult,fat_clusters=0;
	int debug,error,fat,cp;
	int blksize = 512;
	int fat32;
	struct fat_mount_options opts;
	char buf[50];
	int i;
	char cvf_format[21];
	char cvf_options[101];

	cvf_format[0] = '\0';
	cvf_options[0] = '\0';
	MSDOS_SB(sb)->cvf_format = NULL;
	MSDOS_SB(sb)->private_data = NULL;

	MOD_INC_USE_COUNT;
	MSDOS_SB(sb)->dir_ops = fs_dir_inode_ops;
	MSDOS_SB(sb)->put_super_callback = NULL;
	sb->s_op = &fat_sops;
	if (hardsect_size[MAJOR(sb->s_dev)] != NULL){
		blksize = hardsect_size[MAJOR(sb->s_dev)][MINOR(sb->s_dev)];
		if (blksize != 512){
			printk ("MSDOS: Hardware sector size is %d\n",blksize);
		}

	}

	opts.isvfat = MSDOS_SB(sb)->options.isvfat;
	if (!parse_options((char *) data, &fat, &blksize, &debug, &opts, 
			   cvf_format, cvf_options)
	    || (blksize != 512 && blksize != 1024 && blksize != 2048))
		goto out_fail;
	/* N.B. we should parse directly into the sb structure */
	memcpy(&(MSDOS_SB(sb)->options), &opts, sizeof(struct fat_mount_options));

	fat_cache_init();
	lock_super(sb);
	if( blksize > 1024 )
	  {
	    /* Force the superblock to a larger size here. */
	    sb->s_blocksize = blksize;
	    set_blocksize(sb->s_dev, blksize);
	  }
	else
	  {
	    /* The first read is always 1024 bytes */
	    sb->s_blocksize = 1024;
	    set_blocksize(sb->s_dev, 1024);
	  }
	bh = fat_bread(sb, 0);
	unlock_super(sb);
	if (bh == NULL || !fat_is_uptodate(sb,bh)) {
		fat_brelse (sb, bh);
		goto out_no_bread;
	}

/*
 * The DOS3 partition size limit is *not* 32M as many people think.  
 * Instead, it is 64K sectors (with the usual sector size being
 * 512 bytes, leading to a 32M limit).
 * 
 * DOS 3 partition managers got around this problem by faking a 
 * larger sector size, ie treating multiple physical sectors as 
 * a single logical sector.
 * 
 * We can accommodate this scheme by adjusting our cluster size,
 * fat_start, and data_start by an appropriate value.
 *
 * (by Drew Eckhardt)
 */

#define ROUND_TO_MULTIPLE(n,m) ((n) && (m) ? (n)+(m)-1-((n)-1)%(m) : 0)
    /* don't divide by zero */

	b = (struct fat_boot_sector *) bh->b_data;
	logical_sector_size =
		CF_LE_W(get_unaligned((unsigned short *) &b->sector_size));
	sector_mult = logical_sector_size >> SECTOR_BITS;
	MSDOS_SB(sb)->cluster_size = b->cluster_size*sector_mult;
	MSDOS_SB(sb)->fats = b->fats;
	MSDOS_SB(sb)->fat_start = CF_LE_W(b->reserved)*sector_mult;
	if (!b->fat_length && b->fat32_length) {
		struct fat_boot_fsinfo *fsinfo;

		/* Must be FAT32 */
		fat32 = 1;
		MSDOS_SB(sb)->fat_length= CF_LE_L(b->fat32_length)*sector_mult;
		MSDOS_SB(sb)->root_cluster = CF_LE_L(b->root_cluster);

		/* MC - if info_sector is 0, don't multiply by 0 */
		if(CF_LE_W(b->info_sector) == 0) {
			MSDOS_SB(sb)->fsinfo_offset =
	 			logical_sector_size + 0x1e0;
		} else {
			MSDOS_SB(sb)->fsinfo_offset =
				(CF_LE_W(b->info_sector) * logical_sector_size)
				+ 0x1e0;
		}
		if (MSDOS_SB(sb)->fsinfo_offset + sizeof(struct fat_boot_fsinfo) > sb->s_blocksize) {
			printk("fat_read_super: Bad fsinfo_offset\n");
			fat_brelse(sb, bh);
			goto out_invalid;
		}
		fsinfo = (struct fat_boot_fsinfo *)
			&bh->b_data[MSDOS_SB(sb)->fsinfo_offset];
		if (CF_LE_L(fsinfo->signature) != 0x61417272) {
			printk("fat_read_super: Did not find valid FSINFO "
				"signature. Found 0x%x\n",
				CF_LE_L(fsinfo->signature));
		} else {
			MSDOS_SB(sb)->free_clusters = CF_LE_L(fsinfo->free_clusters);
		}
	} else {
		fat32 = 0;
		MSDOS_SB(sb)->fat_length = CF_LE_W(b->fat_length)*sector_mult;
		MSDOS_SB(sb)->root_cluster = 0;
		MSDOS_SB(sb)->free_clusters = -1; /* Don't know yet */
	}
	MSDOS_SB(sb)->dir_start= CF_LE_W(b->reserved)*sector_mult+
	    b->fats*MSDOS_SB(sb)->fat_length;
	MSDOS_SB(sb)->dir_entries =
		CF_LE_W(get_unaligned((unsigned short *) &b->dir_entries));
	MSDOS_SB(sb)->data_start = MSDOS_SB(sb)->dir_start+ROUND_TO_MULTIPLE((
	    MSDOS_SB(sb)->dir_entries << MSDOS_DIR_BITS) >> SECTOR_BITS,
	    sector_mult);
	data_sectors = CF_LE_W(get_unaligned((unsigned short *) &b->sectors));
	if (!data_sectors) {
		data_sectors = CF_LE_L(b->total_sect);
	}
	data_sectors = data_sectors * sector_mult - MSDOS_SB(sb)->data_start;
	error = !b->cluster_size || !sector_mult;
	if (!error) {
		MSDOS_SB(sb)->clusters = b->cluster_size ? data_sectors/
		    b->cluster_size/sector_mult : 0;
		MSDOS_SB(sb)->fat_bits = fat32 ? 32 :
			(fat ? fat :
			 (MSDOS_SB(sb)->clusters > MSDOS_FAT12 ? 16 : 12));
		fat_clusters = MSDOS_SB(sb)->fat_length*SECTOR_SIZE*8/
		    MSDOS_SB(sb)->fat_bits;
		error = !MSDOS_SB(sb)->fats || (MSDOS_SB(sb)->dir_entries &
		    (MSDOS_DPS-1)) || MSDOS_SB(sb)->clusters+2 > fat_clusters+
		    MSDOS_MAX_EXTRA || (logical_sector_size & (SECTOR_SIZE-1))
		    || !b->secs_track || !b->heads;
	}
	fat_brelse(sb, bh);
	set_blocksize(sb->s_dev, blksize);
	/*
		This must be done after the brelse because the bh is a dummy
		allocated by fat_bread (see buffer.c)
	*/
	sb->s_blocksize = blksize;    /* Using this small block size solves */
				/* the misfit with buffer cache and cluster */
				/* because clusters (DOS) are often aligned */
				/* on odd sectors. */
	sb->s_blocksize_bits = blksize == 512 ? 9 : (blksize == 1024 ? 10 : 11);
	if (!strcmp(cvf_format,"none"))
		i = -1;
	else
		i = detect_cvf(sb,cvf_format);
	if (i >= 0)
		error = cvf_formats[i]->mount_cvf(sb,cvf_options);
	if (error || debug) {
		/* The MSDOS_CAN_BMAP is obsolete, but left just to remember */
		printk("[MS-DOS FS Rel. 12,FAT %d,check=%c,conv=%c,"
		       "uid=%d,gid=%d,umask=%03o%s]\n",
		       MSDOS_SB(sb)->fat_bits,opts.name_check,
		       opts.conversion,opts.fs_uid,opts.fs_gid,opts.fs_umask,
		       MSDOS_CAN_BMAP(MSDOS_SB(sb)) ? ",bmap" : "");
		printk("[me=0x%x,cs=%d,#f=%d,fs=%d,fl=%ld,ds=%ld,de=%d,data=%ld,"
		       "se=%d,ts=%ld,ls=%d,rc=%ld,fc=%u]\n",
			b->media,MSDOS_SB(sb)->cluster_size,
			MSDOS_SB(sb)->fats,MSDOS_SB(sb)->fat_start,
			MSDOS_SB(sb)->fat_length,
		       MSDOS_SB(sb)->dir_start,MSDOS_SB(sb)->dir_entries,
		       MSDOS_SB(sb)->data_start,
		       CF_LE_W(*(unsigned short *) &b->sectors),
		       (unsigned long)b->total_sect,logical_sector_size,
		       MSDOS_SB(sb)->root_cluster,MSDOS_SB(sb)->free_clusters);
		printk ("Transaction block size = %d\n",blksize);
	}
	if (i<0) if (MSDOS_SB(sb)->clusters+2 > fat_clusters)
		MSDOS_SB(sb)->clusters = fat_clusters-2;
	if (error)
		goto out_invalid;

	sb->s_magic = MSDOS_SUPER_MAGIC;
	/* set up enough so that it can read an inode */
	MSDOS_SB(sb)->fat_wait = NULL;
	MSDOS_SB(sb)->fat_lock = 0;
	MSDOS_SB(sb)->prev_free = 0;

	cp = opts.codepage ? opts.codepage : 437;
	sprintf(buf, "cp%d", cp);
	MSDOS_SB(sb)->nls_disk = load_nls(buf);
	if (! MSDOS_SB(sb)->nls_disk) {
		/* Fail only if explicit charset specified */
		if (opts.codepage != 0)
			goto out_fail;
		MSDOS_SB(sb)->options.codepage = 0; /* already 0?? */
		MSDOS_SB(sb)->nls_disk = load_nls_default();
	}

	MSDOS_SB(sb)->nls_io = NULL;
	if (MSDOS_SB(sb)->options.isvfat && !opts.utf8) {
		p = opts.iocharset ? opts.iocharset : CONFIG_NLS_DEFAULT;
		MSDOS_SB(sb)->nls_io = load_nls(p);
		if (! MSDOS_SB(sb)->nls_io) {
			/* Fail only if explicit charset specified */
			if (opts.iocharset)
				goto out_unload_nls;
			MSDOS_SB(sb)->nls_io = load_nls_default();
		}
	}

	root_inode=get_empty_inode();
	if (!root_inode)
		goto out_unload_nls;
	root_inode->i_sb = sb;
	root_inode->i_dev = sb->s_dev;
	root_inode->i_ino = MSDOS_ROOT_INO;
	fat_read_root(root_inode);
	insert_inode_hash(root_inode);
	sb->s_root = d_alloc_root(root_inode, NULL);
	if (!sb->s_root)
		goto out_no_root;
	if(i>=0) {
		MSDOS_SB(sb)->cvf_format = cvf_formats[i];
		++cvf_format_use_count[i];
	}
	return sb;

out_no_root:
	printk("get root inode failed\n");
	iput(root_inode);
	if (MSDOS_SB(sb)->nls_io)
		unload_nls(MSDOS_SB(sb)->nls_io);
out_unload_nls:
	unload_nls(MSDOS_SB(sb)->nls_disk);
	goto out_fail;
out_invalid:
	if (!silent)
		printk("VFS: Can't find a valid MSDOS filesystem on dev %s.\n",
			kdevname(sb->s_dev));
	goto out_fail;
out_no_bread:
	printk("FAT bread failed\n");
out_fail:
	if (opts.iocharset) {
		printk("VFS: freeing iocharset=%s\n", opts.iocharset);
		kfree(opts.iocharset);
	}
	sb->s_dev = 0;
	if(MSDOS_SB(sb)->private_data)kfree(MSDOS_SB(sb)->private_data);
	MSDOS_SB(sb)->private_data=NULL;
 
	MOD_DEC_USE_COUNT;
	return NULL;
}

int fat_statfs(struct super_block *sb,struct statfs *buf, int bufsiz)
{
	int free,nr;
	struct statfs tmp;
       
	if (MSDOS_SB(sb)->cvf_format &&
	    MSDOS_SB(sb)->cvf_format->cvf_statfs)
		return MSDOS_SB(sb)->cvf_format->cvf_statfs(sb,buf,bufsiz);
	  
	lock_fat(sb);
	if (MSDOS_SB(sb)->free_clusters != -1)
		free = MSDOS_SB(sb)->free_clusters;
	else {
		free = 0;
		for (nr = 2; nr < MSDOS_SB(sb)->clusters+2; nr++)
			if (!fat_access(sb,nr,-1)) free++;
		MSDOS_SB(sb)->free_clusters = free;
	}
	unlock_fat(sb);
	tmp.f_type = sb->s_magic;
	tmp.f_bsize = MSDOS_SB(sb)->cluster_size*SECTOR_SIZE;
	tmp.f_blocks = MSDOS_SB(sb)->clusters;
	tmp.f_bfree = free;
	tmp.f_bavail = free;
	tmp.f_files = 0;
	tmp.f_ffree = 0;
	tmp.f_namelen = MSDOS_SB(sb)->options.isvfat ? 260 : 12;
	return copy_to_user(buf, &tmp, bufsiz) ? -EFAULT : 0;
}


int fat_bmap(struct inode *inode,int block)
{
	struct msdos_sb_info *sb;
	int cluster,offset;

	sb = MSDOS_SB(inode->i_sb);
	if (sb->cvf_format &&
	    sb->cvf_format->cvf_bmap)
		return sb->cvf_format->cvf_bmap(inode,block);
	if ((inode->i_ino == MSDOS_ROOT_INO) && (sb->fat_bits != 32)) {
		return sb->dir_start + block;
	}
	cluster = block/sb->cluster_size;
	offset = block % sb->cluster_size;
	if (!(cluster = fat_get_cluster(inode,cluster))) return 0;
	return (cluster-2)*sb->cluster_size+sb->data_start+offset;
}

static int is_exec(char *extension)
{
	char *exe_extensions = "EXECOMBAT", *walk;

	for (walk = exe_extensions; *walk; walk += 3)
		if (!strncmp(extension, walk, 3))
			return 1;
	return 0;
}

/* doesn't deal with root inode */
static void fat_fill_inode(struct inode *inode, struct msdos_dir_entry *de)
{
	struct super_block *sb = inode->i_sb;
	int nr;

	MSDOS_I(inode)->i_binary = 1;
	INIT_LIST_HEAD(&MSDOS_I(inode)->i_fat_hash);
	MSDOS_I(inode)->i_location = 0;
	MSDOS_I(inode)->i_fat_inode = inode;
	inode->i_uid = MSDOS_SB(sb)->options.fs_uid;
	inode->i_gid = MSDOS_SB(sb)->options.fs_gid;
	inode->i_version = ++global_event;
	if ((de->attr & ATTR_DIR) && !IS_FREE(de->name)) {
		MSDOS_I(inode)->i_last_pos = 0;
		inode->i_mode = MSDOS_MKMODE(de->attr,S_IRWXUGO &
		    ~MSDOS_SB(sb)->options.fs_umask) | S_IFDIR;
		inode->i_op = MSDOS_SB(inode->i_sb)->dir_ops;

		MSDOS_I(inode)->i_start = CF_LE_W(de->start);
		if (MSDOS_SB(sb)->fat_bits == 32) {
			MSDOS_I(inode)->i_start |=
				(CF_LE_W(de->starthi) << 16);
		}
		MSDOS_I(inode)->i_logstart = MSDOS_I(inode)->i_start;
		inode->i_nlink = fat_subdirs(inode);
		    /* includes .., compensating for "self" */
#ifdef DEBUG
		if (!inode->i_nlink) {
			printk("directory %d: i_nlink == 0\n",inode->i_ino);
			inode->i_nlink = 1;
		}
#endif
		inode->i_size = 0;
		if ((nr = MSDOS_I(inode)->i_start) != 0)
			while (nr != -1) {
				inode->i_size += SECTOR_SIZE*MSDOS_SB(inode->
				    i_sb)->cluster_size;
				if (!(nr = fat_access(sb,nr,-1))) {
					printk("Directory %ld: bad FAT\n",
					    inode->i_ino);
					break;
				}
			}
	} else { /* not a directory */
		inode->i_mode = MSDOS_MKMODE(de->attr,
		    ((IS_NOEXEC(inode) || 
		      (MSDOS_SB(sb)->options.showexec &&
		       !is_exec(de->ext)))
		    	? S_IRUGO|S_IWUGO : S_IRWXUGO)
		    & ~MSDOS_SB(sb)->options.fs_umask) | S_IFREG;
		if (MSDOS_SB(sb)->cvf_format)
			inode->i_op = (MSDOS_SB(sb)->cvf_format->flags & CVF_USE_READPAGE)
				? &fat_file_inode_operations_readpage
				: &fat_file_inode_operations_1024;
		else
		  inode->i_op = (sb->s_blocksize == 1024 || sb->s_blocksize == 2048)
			? &fat_file_inode_operations_1024
			: &fat_file_inode_operations;
		MSDOS_I(inode)->i_start = CF_LE_W(de->start);
		if (MSDOS_SB(sb)->fat_bits == 32) {
			MSDOS_I(inode)->i_start |=
				(CF_LE_W(de->starthi) << 16);
		}
		MSDOS_I(inode)->i_logstart = MSDOS_I(inode)->i_start;
		inode->i_nlink = 1;
		inode->i_size = CF_LE_L(de->size);
	}
	if(de->attr & ATTR_SYS)
		if (MSDOS_SB(sb)->options.sys_immutable)
			inode->i_flags |= S_IMMUTABLE;
	MSDOS_I(inode)->i_binary =
	    fat_is_binary(MSDOS_SB(sb)->options.conversion, de->ext);
	MSDOS_I(inode)->i_attrs = de->attr & ATTR_UNUSED;
	/* this is as close to the truth as we can get ... */
	inode->i_blksize = MSDOS_SB(sb)->cluster_size*SECTOR_SIZE;
	inode->i_blocks = (inode->i_size+inode->i_blksize-1)/
	    inode->i_blksize*MSDOS_SB(sb)->cluster_size;
	inode->i_mtime = inode->i_atime =
	    date_dos2unix(CF_LE_W(de->time),CF_LE_W(de->date));
	inode->i_ctime =
		MSDOS_SB(sb)->options.isvfat
		? date_dos2unix(CF_LE_W(de->ctime),CF_LE_W(de->cdate))
		: inode->i_mtime;
	MSDOS_I(inode)->i_ctime_ms = de->ctime_ms;
}

void fat_write_inode(struct inode *inode)
{
	struct super_block *sb = inode->i_sb;
	struct buffer_head *bh;
	struct msdos_dir_entry *raw_entry;
	int i_pos;

retry:
	i_pos = MSDOS_I(inode)->i_location;
	if (inode->i_ino == MSDOS_ROOT_INO || !i_pos) return;
	if (!(bh = fat_bread(sb, i_pos >> MSDOS_DPB_BITS))) {
		printk("dev = %s, ino = %d\n", kdevname(inode->i_dev), i_pos);
		fat_fs_panic(sb, "msdos_write_inode: unable to read i-node block");
		return;
	}
	spin_lock(&fat_inode_lock);
	if (i_pos != MSDOS_I(inode)->i_location) {
		spin_unlock(&fat_inode_lock);
		fat_brelse(sb, bh);
		goto retry;
	}

	raw_entry = &((struct msdos_dir_entry *) (bh->b_data))
	    [i_pos & (MSDOS_DPB-1)];
	if (S_ISDIR(inode->i_mode)) {
		raw_entry->attr = ATTR_DIR;
		raw_entry->size = 0;
	}
	else {
		raw_entry->attr = ATTR_NONE;
		raw_entry->size = CT_LE_L(inode->i_size);
	}
	raw_entry->attr |= MSDOS_MKATTR(inode->i_mode) |
	    MSDOS_I(inode)->i_attrs;
	raw_entry->start = CT_LE_W(MSDOS_I(inode)->i_logstart);
	raw_entry->starthi = CT_LE_W(MSDOS_I(inode)->i_logstart >> 16);
	fat_date_unix2dos(inode->i_mtime,&raw_entry->time,&raw_entry->date);
	raw_entry->time = CT_LE_W(raw_entry->time);
	raw_entry->date = CT_LE_W(raw_entry->date);
	if (MSDOS_SB(sb)->options.isvfat) {
		fat_date_unix2dos(inode->i_ctime,&raw_entry->ctime,&raw_entry->cdate);
		raw_entry->ctime_ms = MSDOS_I(inode)->i_ctime_ms;
		raw_entry->ctime = CT_LE_W(raw_entry->ctime);
		raw_entry->cdate = CT_LE_W(raw_entry->cdate);
	}
	spin_unlock(&fat_inode_lock);
	fat_mark_buffer_dirty(sb, bh, 1);
	fat_brelse(sb, bh);
}


int fat_notify_change(struct dentry * dentry, struct iattr * attr)
{
	struct super_block *sb = dentry->d_sb;
	struct inode *inode = dentry->d_inode;
	int error;

	error = inode_change_ok(inode, attr);
	if (error)
		return MSDOS_SB(sb)->options.quiet ? 0 : error;

	if (((attr->ia_valid & ATTR_UID) && 
	     (attr->ia_uid != MSDOS_SB(sb)->options.fs_uid)) ||
	    ((attr->ia_valid & ATTR_GID) && 
	     (attr->ia_gid != MSDOS_SB(sb)->options.fs_gid)) ||
	    ((attr->ia_valid & ATTR_MODE) &&
	     (attr->ia_mode & ~MSDOS_VALID_MODE)))
		error = -EPERM;

	if (error)
		return MSDOS_SB(sb)->options.quiet ? 0 : error;

	inode_setattr(inode, attr);

	if (IS_NOEXEC(inode) && !S_ISDIR(inode->i_mode))
		inode->i_mode &= S_IFMT | S_IRUGO | S_IWUGO;
	else
		inode->i_mode |= S_IXUGO;

	inode->i_mode = ((inode->i_mode & S_IFMT) | ((((inode->i_mode & S_IRWXU
	    & ~MSDOS_SB(sb)->options.fs_umask) | S_IRUSR) >> 6)*S_IXUGO)) &
	    ~MSDOS_SB(sb)->options.fs_umask;
	return 0;
}


#ifdef MODULE
int init_module(void)
{
	return init_fat_fs();
}


void cleanup_module(void)
{
	/* Nothing to be done, really! */
	return;
}
#endif