rem: get_mount(mount_id id)
add: get_mount(mount_id id, struct fs_mount **_mount)
context: get_mount(mount_id id){	struct fs_mount *mount;	mutex_lock(&sMountMutex);	mount = find_mount(id);	if (mount) {		// ToDo: the volume is locked (against removal) by locking		//	its root node - investigate if that's a good idea		if (mount->root_vnode)			inc_vnode_ref_count(mount->root_vnode);		else			mount = NULL;	}	mutex_unlock(&sMountMutex);	return mount;}