read_efi_label
int read_efi_label(int, struct efi_info *, struct disk_info *);
status = read_efi_label(cur_file, &efi_info, cur_disk);
status = read_efi_label(search_file, &efi_info, search_disk);
if (read_efi_label(config, &sb, NULL) < 0)
static int read_efi_label(nvlist_t *, diskaddr_t *, boolean_t *);