freebsd系统下如何使用系统调用mount, 高手帮个忙啊！

xfming

freebsd系统下如何使用系统调用mount, 高手帮个忙啊！
manual page函数原型是这样
int mount(const char *type, const char *dir, int flags, void *data);
关键是第四个参数data该如何指定，说明的比较含糊：
The data argument is a pointer to a structure that contains the type specific arguments to mount. The format for these argument structures is described in the manual page for each file system. By convention file system manual pages are named by prefixing ``mount_'' to the name of the file system as returned by lsvfs(1). Thus the NFS file system is described by the mount_nfs( manual page.

但是mount(我看了，也不明白data的结构。
望高手指点一下，救急阿！