(i) The prototypes for free_vfsmnt(), alloc_vfsmnt(), do_kern_mount()
    so far occurred in several individual c files.  Now they are in
    <linux/mount.h>.

(ii) do_kern_mount() has a third argument name that is typically a
     constant.  It is called with "rootfs", "nfsd", type->name,
     "capifs", "usbdevfs", "binfmt_misc" etc.  So, it should have a
     prototype that expresses this:

	do_kern_mount(const char *fstype, int flags, const char *name, void *data);

This makes the ugly cast

-       return do_kern_mount(type->name, 0, (char *)type->name, NULL);
+       return do_kern_mount(type->name, 0, type->name, NULL);

go away. Now do_kern_mount() calls type->get_sb(), so also get_sb()
must have a const third argument. That is what the patch below does.

If I am not mistaken, precisely two filesystems do not treat this
argument as a constant, namely afs and cifs. A separate patch
gives some cleanup there.