xref: /openbmc/linux/fs/befs/linuxvfs.c (revision 1a1d92c10dd24bbdc28b3d6e2d03ec199dd3a65b)

/*
 * linux/fs/befs/linuxvfs.c
 *
 * Copyright (C) 2001 Will Dyson <will_dyson@pobox.com
 *
 */

#include <linux/module.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/stat.h>
#include <linux/nls.h>
#include <linux/buffer_head.h>
#include <linux/vfs.h>
#include <linux/parser.h>
#include <linux/namei.h>

#include "befs.h"
#include "btree.h"
#include "inode.h"
#include "datastream.h"
#include "super.h"
#include "io.h"
#include "endian.h"

MODULE_DESCRIPTION("BeOS File System (BeFS) driver");
MODULE_AUTHOR("Will Dyson");
MODULE_LICENSE("GPL");

/* The units the vfs expects inode->i_blocks to be in */
#define VFS_BLOCK_SIZE 512

static int befs_readdir(struct file *, void *, filldir_t);
static int befs_get_block(struct inode *, sector_t, struct buffer_head *, int);
static int befs_readpage(struct file *file, struct page *page);
static sector_t befs_bmap(struct address_space *mapping, sector_t block);
static struct dentry *befs_lookup(struct inode *, struct dentry *, struct nameidata *);
static void befs_read_inode(struct inode *ino);
static struct inode *befs_alloc_inode(struct super_block *sb);
static void befs_destroy_inode(struct inode *inode);
static int befs_init_inodecache(void);
static void befs_destroy_inodecache(void);
static void *befs_follow_link(struct dentry *, struct nameidata *);
static void befs_put_link(struct dentry *, struct nameidata *, void *);
static int befs_utf2nls(struct super_block *sb, const char *in, int in_len,
			char **out, int *out_len);
static int befs_nls2utf(struct super_block *sb, const char *in, int in_len,
			char **out, int *out_len);
static void befs_put_super(struct super_block *);
static int befs_remount(struct super_block *, int *, char *);
static int befs_statfs(struct dentry *, struct kstatfs *);
static int parse_options(char *, befs_mount_options *);

static const struct super_operations befs_sops = {
	.read_inode	= befs_read_inode,	/* initialize & read inode */
	.alloc_inode	= befs_alloc_inode,	/* allocate a new inode */
	.destroy_inode	= befs_destroy_inode, /* deallocate an inode */
	.put_super	= befs_put_super,	/* uninit super */
	.statfs		= befs_statfs,	/* statfs */
	.remount_fs	= befs_remount,
};

/* slab cache for befs_inode_info objects */
static kmem_cache_t *befs_inode_cachep;

static const struct file_operations befs_dir_operations = {
	.read		= generic_read_dir,
	.readdir	= befs_readdir,
};

static struct inode_operations befs_dir_inode_operations = {
	.lookup		= befs_lookup,
};

static const struct address_space_operations befs_aops = {
	.readpage	= befs_readpage,
	.sync_page	= block_sync_page,
	.bmap		= befs_bmap,
};

static struct inode_operations befs_symlink_inode_operations = {
	.readlink	= generic_readlink,
	.follow_link	= befs_follow_link,
	.put_link	= befs_put_link,
};

/*
 * Called by generic_file_read() to read a page of data
 *
 * In turn, simply calls a generic block read function and
 * passes it the address of befs_get_block, for mapping file
 * positions to disk blocks.
 */
static int
befs_readpage(struct file *file, struct page *page)
{
	return block_read_full_page(page, befs_get_block);
}

static sector_t
befs_bmap(struct address_space *mapping, sector_t block)
{
	return generic_block_bmap(mapping, block, befs_get_block);
}

/*
 * Generic function to map a file position (block) to a
 * disk offset (passed back in bh_result).
 *
 * Used by many higher level functions.
 *
 * Calls befs_fblock2brun() in datastream.c to do the real work.
 *
 * -WD 10-26-01
 */

static int
befs_get_block(struct inode *inode, sector_t block,
	       struct buffer_head *bh_result, int create)
{
	struct super_block *sb = inode->i_sb;
	befs_data_stream *ds = &BEFS_I(inode)->i_data.ds;
	befs_block_run run = BAD_IADDR;
	int res = 0;
	ulong disk_off;

	befs_debug(sb, "---> befs_get_block() for inode %lu, block %ld",
		   inode->i_ino, block);

	if (block < 0) {
		befs_error(sb, "befs_get_block() was asked for a block "
			   "number less than zero: block %ld in inode %lu",
			   block, inode->i_ino);
		return -EIO;
	}

	if (create) {
		befs_error(sb, "befs_get_block() was asked to write to "
			   "block %ld in inode %lu", block, inode->i_ino);
		return -EPERM;
	}

	res = befs_fblock2brun(sb, ds, block, &run);
	if (res != BEFS_OK) {
		befs_error(sb,
			   "<--- befs_get_block() for inode %lu, block "
			   "%ld ERROR", inode->i_ino, block);
		return -EFBIG;
	}

	disk_off = (ulong) iaddr2blockno(sb, &run);

	map_bh(bh_result, inode->i_sb, disk_off);

	befs_debug(sb, "<--- befs_get_block() for inode %lu, block %ld, "
		   "disk address %lu", inode->i_ino, block, disk_off);

	return 0;
}

static struct dentry *
befs_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
{
	struct inode *inode = NULL;
	struct super_block *sb = dir->i_sb;
	befs_data_stream *ds = &BEFS_I(dir)->i_data.ds;
	befs_off_t offset;
	int ret;
	int utfnamelen;
	char *utfname;
	const char *name = dentry->d_name.name;

	befs_debug(sb, "---> befs_lookup() "
		   "name %s inode %ld", dentry->d_name.name, dir->i_ino);

	/* Convert to UTF-8 */
	if (BEFS_SB(sb)->nls) {
		ret =
		    befs_nls2utf(sb, name, strlen(name), &utfname, &utfnamelen);
		if (ret < 0) {
			befs_debug(sb, "<--- befs_lookup() ERROR");
			return ERR_PTR(ret);
		}
		ret = befs_btree_find(sb, ds, utfname, &offset);
		kfree(utfname);

	} else {
		ret = befs_btree_find(sb, ds, dentry->d_name.name, &offset);
	}

	if (ret == BEFS_BT_NOT_FOUND) {
		befs_debug(sb, "<--- befs_lookup() %s not found",
			   dentry->d_name.name);
		return ERR_PTR(-ENOENT);

	} else if (ret != BEFS_OK || offset == 0) {
		befs_warning(sb, "<--- befs_lookup() Error");
		return ERR_PTR(-ENODATA);
	}

	inode = iget(dir->i_sb, (ino_t) offset);
	if (!inode)
		return ERR_PTR(-EACCES);

	d_add(dentry, inode);

	befs_debug(sb, "<--- befs_lookup()");

	return NULL;
}

static int
befs_readdir(struct file *filp, void *dirent, filldir_t filldir)
{
	struct inode *inode = filp->f_dentry->d_inode;
	struct super_block *sb = inode->i_sb;
	befs_data_stream *ds = &BEFS_I(inode)->i_data.ds;
	befs_off_t value;
	int result;
	size_t keysize;
	unsigned char d_type;
	char keybuf[BEFS_NAME_LEN + 1];
	char *nlsname;
	int nlsnamelen;
	const char *dirname = filp->f_dentry->d_name.name;

	befs_debug(sb, "---> befs_readdir() "
		   "name %s, inode %ld, filp->f_pos %Ld",
		   dirname, inode->i_ino, filp->f_pos);

	result = befs_btree_read(sb, ds, filp->f_pos, BEFS_NAME_LEN + 1,
				 keybuf, &keysize, &value);

	if (result == BEFS_ERR) {
		befs_debug(sb, "<--- befs_readdir() ERROR");
		befs_error(sb, "IO error reading %s (inode %lu)",
			   dirname, inode->i_ino);
		return -EIO;

	} else if (result == BEFS_BT_END) {
		befs_debug(sb, "<--- befs_readdir() END");
		return 0;

	} else if (result == BEFS_BT_EMPTY) {
		befs_debug(sb, "<--- befs_readdir() Empty directory");
		return 0;
	}

	d_type = DT_UNKNOWN;

	/* Convert to NLS */
	if (BEFS_SB(sb)->nls) {
		result =
		    befs_utf2nls(sb, keybuf, keysize, &nlsname, &nlsnamelen);
		if (result < 0) {
			befs_debug(sb, "<--- befs_readdir() ERROR");
			return result;
		}
		result = filldir(dirent, nlsname, nlsnamelen, filp->f_pos,
				 (ino_t) value, d_type);
		kfree(nlsname);

	} else {
		result = filldir(dirent, keybuf, keysize, filp->f_pos,
				 (ino_t) value, d_type);
	}

	filp->f_pos++;

	befs_debug(sb, "<--- befs_readdir() filp->f_pos %Ld", filp->f_pos);

	return 0;
}

static struct inode *
befs_alloc_inode(struct super_block *sb)
{
        struct befs_inode_info *bi;
        bi = (struct befs_inode_info *)kmem_cache_alloc(befs_inode_cachep,
							SLAB_KERNEL);
        if (!bi)
                return NULL;
        return &bi->vfs_inode;
}

static void
befs_destroy_inode(struct inode *inode)
{
        kmem_cache_free(befs_inode_cachep, BEFS_I(inode));
}

static void init_once(void * foo, kmem_cache_t * cachep, unsigned long flags)
{
        struct befs_inode_info *bi = (struct befs_inode_info *) foo;

	        if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
		            SLAB_CTOR_CONSTRUCTOR) {
			inode_init_once(&bi->vfs_inode);
		}
}

static void
befs_read_inode(struct inode *inode)
{
	struct buffer_head *bh = NULL;
	befs_inode *raw_inode = NULL;

	struct super_block *sb = inode->i_sb;
	befs_sb_info *befs_sb = BEFS_SB(sb);
	befs_inode_info *befs_ino = NULL;

	befs_debug(sb, "---> befs_read_inode() " "inode = %lu", inode->i_ino);

	befs_ino = BEFS_I(inode);

	/* convert from vfs's inode number to befs's inode number */
	befs_ino->i_inode_num = blockno2iaddr(sb, inode->i_ino);

	befs_debug(sb, "  real inode number [%u, %hu, %hu]",
		   befs_ino->i_inode_num.allocation_group,
		   befs_ino->i_inode_num.start, befs_ino->i_inode_num.len);

	bh = befs_bread(sb, inode->i_ino);
	if (!bh) {
		befs_error(sb, "unable to read inode block - "
			   "inode = %lu", inode->i_ino);
		goto unacquire_none;
	}

	raw_inode = (befs_inode *) bh->b_data;

	befs_dump_inode(sb, raw_inode);

	if (befs_check_inode(sb, raw_inode, inode->i_ino) != BEFS_OK) {
		befs_error(sb, "Bad inode: %lu", inode->i_ino);
		goto unacquire_bh;
	}

	inode->i_mode = (umode_t) fs32_to_cpu(sb, raw_inode->mode);

	/*
	 * set uid and gid.  But since current BeOS is single user OS, so
	 * you can change by "uid" or "gid" options.
	 */

	inode->i_uid = befs_sb->mount_opts.use_uid ?
	    befs_sb->mount_opts.uid : (uid_t) fs32_to_cpu(sb, raw_inode->uid);
	inode->i_gid = befs_sb->mount_opts.use_gid ?
	    befs_sb->mount_opts.gid : (gid_t) fs32_to_cpu(sb, raw_inode->gid);

	inode->i_nlink = 1;

	/*
	 * BEFS's time is 64 bits, but current VFS is 32 bits...
	 * BEFS don't have access time. Nor inode change time. VFS
	 * doesn't have creation time.
	 * Also, the lower 16 bits of the last_modified_time and
	 * create_time are just a counter to help ensure uniqueness
	 * for indexing purposes. (PFD, page 54)
	 */

	inode->i_mtime.tv_sec =
	    fs64_to_cpu(sb, raw_inode->last_modified_time) >> 16;
	inode->i_mtime.tv_nsec = 0;   /* lower 16 bits are not a time */
	inode->i_ctime = inode->i_mtime;
	inode->i_atime = inode->i_mtime;
	inode->i_blksize = befs_sb->block_size;

	befs_ino->i_inode_num = fsrun_to_cpu(sb, raw_inode->inode_num);
	befs_ino->i_parent = fsrun_to_cpu(sb, raw_inode->parent);
	befs_ino->i_attribute = fsrun_to_cpu(sb, raw_inode->attributes);
	befs_ino->i_flags = fs32_to_cpu(sb, raw_inode->flags);

	if (S_ISLNK(inode->i_mode) && !(befs_ino->i_flags & BEFS_LONG_SYMLINK)){
		inode->i_size = 0;
		inode->i_blocks = befs_sb->block_size / VFS_BLOCK_SIZE;
		strncpy(befs_ino->i_data.symlink, raw_inode->data.symlink,
			BEFS_SYMLINK_LEN);
	} else {
		int num_blks;

		befs_ino->i_data.ds =
		    fsds_to_cpu(sb, raw_inode->data.datastream);

		num_blks = befs_count_blocks(sb, &befs_ino->i_data.ds);
		inode->i_blocks =
		    num_blks * (befs_sb->block_size / VFS_BLOCK_SIZE);
		inode->i_size = befs_ino->i_data.ds.size;
	}

	inode->i_mapping->a_ops = &befs_aops;

	if (S_ISREG(inode->i_mode)) {
		inode->i_fop = &generic_ro_fops;
	} else if (S_ISDIR(inode->i_mode)) {
		inode->i_op = &befs_dir_inode_operations;
		inode->i_fop = &befs_dir_operations;
	} else if (S_ISLNK(inode->i_mode)) {
		inode->i_op = &befs_symlink_inode_operations;
	} else {
		befs_error(sb, "Inode %lu is not a regular file, "
			   "directory or symlink. THAT IS WRONG! BeFS has no "
			   "on disk special files", inode->i_ino);
		goto unacquire_bh;
	}

	brelse(bh);
	befs_debug(sb, "<--- befs_read_inode()");
	return;

      unacquire_bh:
	brelse(bh);

      unacquire_none:
	make_bad_inode(inode);
	befs_debug(sb, "<--- befs_read_inode() - Bad inode");
	return;
}

/* Initialize the inode cache. Called at fs setup.
 *
 * Taken from NFS implementation by Al Viro.
 */
static int
befs_init_inodecache(void)
{
	befs_inode_cachep = kmem_cache_create("befs_inode_cache",
					      sizeof (struct befs_inode_info),
					      0, (SLAB_RECLAIM_ACCOUNT|
						SLAB_MEM_SPREAD),
					      init_once, NULL);
	if (befs_inode_cachep == NULL) {
		printk(KERN_ERR "befs_init_inodecache: "
		       "Couldn't initalize inode slabcache\n");
		return -ENOMEM;
	}

	return 0;
}

/* Called at fs teardown.
 *
 * Taken from NFS implementation by Al Viro.
 */
static void
befs_destroy_inodecache(void)
{
	kmem_cache_destroy(befs_inode_cachep);
}

/*
 * The inode of symbolic link is different to data stream.
 * The data stream become link name. Unless the LONG_SYMLINK
 * flag is set.
 */
static void *
befs_follow_link(struct dentry *dentry, struct nameidata *nd)
{
	befs_inode_info *befs_ino = BEFS_I(dentry->d_inode);
	char *link;

	if (befs_ino->i_flags & BEFS_LONG_SYMLINK) {
		struct super_block *sb = dentry->d_sb;
		befs_data_stream *data = &befs_ino->i_data.ds;
		befs_off_t len = data->size;

		befs_debug(sb, "Follow long symlink");

		link = kmalloc(len, GFP_NOFS);
		if (!link) {
			link = ERR_PTR(-ENOMEM);
		} else if (befs_read_lsymlink(sb, data, link, len) != len) {
			kfree(link);
			befs_error(sb, "Failed to read entire long symlink");
			link = ERR_PTR(-EIO);
		}
	} else {
		link = befs_ino->i_data.symlink;
	}

	nd_set_link(nd, link);
	return NULL;
}

static void befs_put_link(struct dentry *dentry, struct nameidata *nd, void *p)
{
	befs_inode_info *befs_ino = BEFS_I(dentry->d_inode);
	if (befs_ino->i_flags & BEFS_LONG_SYMLINK) {
		char *p = nd_get_link(nd);
		if (!IS_ERR(p))
			kfree(p);
	}
}

/*
 * UTF-8 to NLS charset  convert routine
 *
 *
 * Changed 8/10/01 by Will Dyson. Now use uni2char() / char2uni() rather than
 * the nls tables directly
 */

static int
befs_utf2nls(struct super_block *sb, const char *in,
	     int in_len, char **out, int *out_len)
{
	struct nls_table *nls = BEFS_SB(sb)->nls;
	int i, o;
	wchar_t uni;
	int unilen, utflen;
	char *result;
	/* The utf8->nls conversion won't make the final nls string bigger
	 * than the utf one, but if the string is pure ascii they'll have the
	 * same width and an extra char is needed to save the additional \0
	 */
	int maxlen = in_len + 1;

	befs_debug(sb, "---> utf2nls()");

	if (!nls) {
		befs_error(sb, "befs_utf2nls called with no NLS table loaded");
		return -EINVAL;
	}

	*out = result = kmalloc(maxlen, GFP_NOFS);
	if (!*out) {
		befs_error(sb, "befs_utf2nls() cannot allocate memory");
		*out_len = 0;
		return -ENOMEM;
	}

	for (i = o = 0; i < in_len; i += utflen, o += unilen) {

		/* convert from UTF-8 to Unicode */
		utflen = utf8_mbtowc(&uni, &in[i], in_len - i);
		if (utflen < 0) {
			goto conv_err;
		}

		/* convert from Unicode to nls */
		unilen = nls->uni2char(uni, &result[o], in_len - o);
		if (unilen < 0) {
			goto conv_err;
		}
	}
	result[o] = '\0';
	*out_len = o;

	befs_debug(sb, "<--- utf2nls()");

	return o;

      conv_err:
	befs_error(sb, "Name using character set %s contains a character that "
		   "cannot be converted to unicode.", nls->charset);
	befs_debug(sb, "<--- utf2nls()");
	kfree(result);
	return -EILSEQ;
}

/**
 * befs_nls2utf - Convert NLS string to utf8 encodeing
 * @sb: Superblock
 * @src: Input string buffer in NLS format
 * @srclen: Length of input string in bytes
 * @dest: The output string in UTF-8 format
 * @destlen: Length of the output buffer
 *
 * Converts input string @src, which is in the format of the loaded NLS map,
 * into a utf8 string.
 *
 * The destination string @dest is allocated by this function and the caller is
 * responsible for freeing it with kfree()
 *
 * On return, *@destlen is the length of @dest in bytes.
 *
 * On success, the return value is the number of utf8 characters written to
 * the output buffer @dest.
 *
 * On Failure, a negative number coresponding to the error code is returned.
 */

static int
befs_nls2utf(struct super_block *sb, const char *in,
	     int in_len, char **out, int *out_len)
{
	struct nls_table *nls = BEFS_SB(sb)->nls;
	int i, o;
	wchar_t uni;
	int unilen, utflen;
	char *result;
	/* There're nls characters that will translate to 3-chars-wide UTF-8
	 * characters, a additional byte is needed to save the final \0
	 * in special cases */
	int maxlen = (3 * in_len) + 1;

	befs_debug(sb, "---> nls2utf()\n");

	if (!nls) {
		befs_error(sb, "befs_nls2utf called with no NLS table loaded.");
		return -EINVAL;
	}

	*out = result = kmalloc(maxlen, GFP_NOFS);
	if (!*out) {
		befs_error(sb, "befs_nls2utf() cannot allocate memory");
		*out_len = 0;
		return -ENOMEM;
	}

	for (i = o = 0; i < in_len; i += unilen, o += utflen) {

		/* convert from nls to unicode */
		unilen = nls->char2uni(&in[i], in_len - i, &uni);
		if (unilen < 0) {
			goto conv_err;
		}

		/* convert from unicode to UTF-8 */
		utflen = utf8_wctomb(&result[o], uni, 3);
		if (utflen <= 0) {
			goto conv_err;
		}
	}

	result[o] = '\0';
	*out_len = o;

	befs_debug(sb, "<--- nls2utf()");

	return i;

      conv_err:
	befs_error(sb, "Name using charecter set %s contains a charecter that "
		   "cannot be converted to unicode.", nls->charset);
	befs_debug(sb, "<--- nls2utf()");
	kfree(result);
	return -EILSEQ;
}

/**
 * Use the
 *
 */
enum {
	Opt_uid, Opt_gid, Opt_charset, Opt_debug, Opt_err,
};

static match_table_t befs_tokens = {
	{Opt_uid, "uid=%d"},
	{Opt_gid, "gid=%d"},
	{Opt_charset, "iocharset=%s"},
	{Opt_debug, "debug"},
	{Opt_err, NULL}
};

static int
parse_options(char *options, befs_mount_options * opts)
{
	char *p;
	substring_t args[MAX_OPT_ARGS];
	int option;

	/* Initialize options */
	opts->uid = 0;
	opts->gid = 0;
	opts->use_uid = 0;
	opts->use_gid = 0;
	opts->iocharset = NULL;
	opts->debug = 0;

	if (!options)
		return 1;

	while ((p = strsep(&options, ",")) != NULL) {
		int token;
		if (!*p)
			continue;

		token = match_token(p, befs_tokens, args);
		switch (token) {
		case Opt_uid:
			if (match_int(&args[0], &option))
				return 0;
			if (option < 0) {
				printk(KERN_ERR "BeFS: Invalid uid %d, "
						"using default\n", option);
				break;
			}
			opts->uid = option;
			opts->use_uid = 1;
			break;
		case Opt_gid:
			if (match_int(&args[0], &option))
				return 0;
			if (option < 0) {
				printk(KERN_ERR "BeFS: Invalid gid %d, "
						"using default\n", option);
				break;
			}
			opts->gid = option;
			opts->use_gid = 1;
			break;
		case Opt_charset:
			kfree(opts->iocharset);
			opts->iocharset = match_strdup(&args[0]);
			if (!opts->iocharset) {
				printk(KERN_ERR "BeFS: allocation failure for "
						"iocharset string\n");
				return 0;
			}
			break;
		case Opt_debug:
			opts->debug = 1;
			break;
		default:
			printk(KERN_ERR "BeFS: Unrecognized mount option \"%s\" "
					"or missing value\n", p);
			return 0;
		}
	}
	return 1;
}

/* This function has the responsibiltiy of getting the
 * filesystem ready for unmounting.
 * Basicly, we free everything that we allocated in
 * befs_read_inode
 */
static void
befs_put_super(struct super_block *sb)
{
	kfree(BEFS_SB(sb)->mount_opts.iocharset);
	BEFS_SB(sb)->mount_opts.iocharset = NULL;

	if (BEFS_SB(sb)->nls) {
		unload_nls(BEFS_SB(sb)->nls);
		BEFS_SB(sb)->nls = NULL;
	}

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

/* Allocate private field of the superblock, fill it.
 *
 * Finish filling the public superblock fields
 * Make the root directory
 * Load a set of NLS translations if needed.
 */
static int
befs_fill_super(struct super_block *sb, void *data, int silent)
{
	struct buffer_head *bh;
	befs_sb_info *befs_sb;
	befs_super_block *disk_sb;
	struct inode *root;

	const unsigned long sb_block = 0;
	const off_t x86_sb_off = 512;

	sb->s_fs_info = kmalloc(sizeof (*befs_sb), GFP_KERNEL);
	if (sb->s_fs_info == NULL) {
		printk(KERN_ERR
		       "BeFS(%s): Unable to allocate memory for private "
		       "portion of superblock. Bailing.\n", sb->s_id);
		goto unacquire_none;
	}
	befs_sb = BEFS_SB(sb);
	memset(befs_sb, 0, sizeof(befs_sb_info));

	if (!parse_options((char *) data, &befs_sb->mount_opts)) {
		befs_error(sb, "cannot parse mount options");
		goto unacquire_priv_sbp;
	}

	befs_debug(sb, "---> befs_fill_super()");

#ifndef CONFIG_BEFS_RW
	if (!(sb->s_flags & MS_RDONLY)) {
		befs_warning(sb,
			     "No write support. Marking filesystem read-only");
		sb->s_flags |= MS_RDONLY;
	}
#endif				/* CONFIG_BEFS_RW */

	/*
	 * Set dummy blocksize to read super block.
	 * Will be set to real fs blocksize later.
	 *
	 * Linux 2.4.10 and later refuse to read blocks smaller than
	 * the hardsect size for the device. But we also need to read at
	 * least 1k to get the second 512 bytes of the volume.
	 * -WD 10-26-01
	 */
	sb_min_blocksize(sb, 1024);

	if (!(bh = sb_bread(sb, sb_block))) {
		befs_error(sb, "unable to read superblock");
		goto unacquire_priv_sbp;
	}

	/* account for offset of super block on x86 */
	disk_sb = (befs_super_block *) bh->b_data;
	if ((le32_to_cpu(disk_sb->magic1) == BEFS_SUPER_MAGIC1) ||
	    (be32_to_cpu(disk_sb->magic1) == BEFS_SUPER_MAGIC1)) {
		befs_debug(sb, "Using PPC superblock location");
	} else {
		befs_debug(sb, "Using x86 superblock location");
		disk_sb =
		    (befs_super_block *) ((void *) bh->b_data + x86_sb_off);
	}

	if (befs_load_sb(sb, disk_sb) != BEFS_OK)
		goto unacquire_bh;

	befs_dump_super_block(sb, disk_sb);

	brelse(bh);

	if (befs_check_sb(sb) != BEFS_OK)
		goto unacquire_priv_sbp;

	if( befs_sb->num_blocks > ~((sector_t)0) ) {
		befs_error(sb, "blocks count: %Lu "
			"is larger than the host can use",
			befs_sb->num_blocks);
		goto unacquire_priv_sbp;
	}

	/*
	 * set up enough so that it can read an inode
	 * Fill in kernel superblock fields from private sb
	 */
	sb->s_magic = BEFS_SUPER_MAGIC;
	/* Set real blocksize of fs */
	sb_set_blocksize(sb, (ulong) befs_sb->block_size);
	sb->s_op = (struct super_operations *) &befs_sops;
	root = iget(sb, iaddr2blockno(sb, &(befs_sb->root_dir)));
	sb->s_root = d_alloc_root(root);
	if (!sb->s_root) {
		iput(root);
		befs_error(sb, "get root inode failed");
		goto unacquire_priv_sbp;
	}

	/* load nls library */
	if (befs_sb->mount_opts.iocharset) {
		befs_debug(sb, "Loading nls: %s",
			   befs_sb->mount_opts.iocharset);
		befs_sb->nls = load_nls(befs_sb->mount_opts.iocharset);
		if (!befs_sb->nls) {
			befs_warning(sb, "Cannot load nls %s"
					" loading default nls",
					befs_sb->mount_opts.iocharset);
			befs_sb->nls = load_nls_default();
		}
	/* load default nls if none is specified  in mount options */
	} else {
		befs_debug(sb, "Loading default nls");
		befs_sb->nls = load_nls_default();
	}

	return 0;
/*****************/
      unacquire_bh:
	brelse(bh);

      unacquire_priv_sbp:
	kfree(sb->s_fs_info);

      unacquire_none:
	sb->s_fs_info = NULL;
	return -EINVAL;
}

static int
befs_remount(struct super_block *sb, int *flags, char *data)
{
	if (!(*flags & MS_RDONLY))
		return -EINVAL;
	return 0;
}

static int
befs_statfs(struct dentry *dentry, struct kstatfs *buf)
{
	struct super_block *sb = dentry->d_sb;

	befs_debug(sb, "---> befs_statfs()");

	buf->f_type = BEFS_SUPER_MAGIC;
	buf->f_bsize = sb->s_blocksize;
	buf->f_blocks = BEFS_SB(sb)->num_blocks;
	buf->f_bfree = BEFS_SB(sb)->num_blocks - BEFS_SB(sb)->used_blocks;
	buf->f_bavail = buf->f_bfree;
	buf->f_files = 0;	/* UNKNOWN */
	buf->f_ffree = 0;	/* UNKNOWN */
	buf->f_namelen = BEFS_NAME_LEN;

	befs_debug(sb, "<--- befs_statfs()");

	return 0;
}

static int
befs_get_sb(struct file_system_type *fs_type, int flags, const char *dev_name,
	    void *data, struct vfsmount *mnt)
{
	return get_sb_bdev(fs_type, flags, dev_name, data, befs_fill_super,
			   mnt);
}

static struct file_system_type befs_fs_type = {
	.owner		= THIS_MODULE,
	.name		= "befs",
	.get_sb		= befs_get_sb,
	.kill_sb	= kill_block_super,
	.fs_flags	= FS_REQUIRES_DEV,
};

static int __init
init_befs_fs(void)
{
	int err;

	printk(KERN_INFO "BeFS version: %s\n", BEFS_VERSION);

	err = befs_init_inodecache();
	if (err)
		goto unacquire_none;

	err = register_filesystem(&befs_fs_type);
	if (err)
		goto unacquire_inodecache;

	return 0;

unacquire_inodecache:
	befs_destroy_inodecache();

unacquire_none:
	return err;
}

static void __exit
exit_befs_fs(void)
{
	befs_destroy_inodecache();

	unregister_filesystem(&befs_fs_type);
}

/*
Macros that typecheck the init and exit functions,
ensures that they are called at init and cleanup,
and eliminates warnings about unused functions.
*/
module_init(init_befs_fs)
module_exit(exit_befs_fs)