int dm_create(struct mapped_device **md);
int dm_create_with_minor(unsigned int minor, struct mapped_device **md);
void dm_set_mdptr(struct mapped_device *md, void *ptr);
int dm_create(struct mapped_device **md);
int dm_create_with_minor(unsigned int minor, struct mapped_device **md);
void dm_set_mdptr(struct mapped_device *md, void *ptr);