part_stat_add
part_stat_add(bdev, sectors[sgrp], sectors);
part_stat_add(bdev, nsecs[sgrp], jiffies_to_nsecs(duration));
part_stat_add(part, nsecs[STAT_FLUSH],
part_stat_add(req->part, nsecs[sgrp], now - req->start_time_ns);
part_stat_add(req->part, sectors[sgrp], bytes >> 9);
part_stat_add(part, field, -1)
part_stat_add(part, field, 1)
part_stat_add(part, field, -subnd)