linuxvfs.c

linux 内核源代码

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)