part_stat_read_accum
curr_events = (int)part_stat_read_accum(disk->part0, sectors) -
(int)part_stat_read_accum(disk->part0, sectors);
rdev->last_events = part_stat_read_accum(rdev->bdev->bd_disk->part0,
part_stat_read_accum(rdev->bdev, sectors);
mddev->normal_io_events = part_stat_read_accum(disk->part0, sectors);