extern int blk_alloc_devt(struct hd_struct *part, dev_t *devt);
extern void blk_free_devt(dev_t devt);
+extern void blk_invalidate_devt(dev_t devt);
extern dev_t blk_lookup_devt(const char *name, int partno);
extern char *disk_name (struct gendisk *hd, int partno, char *buf);