If iostats is disabled, disk_stats will not be updated and
part_stat_read_accum() only returns a constant value. In this case,
continuing to count sync_io and to check is_mddev_idle() is no longer
meaningful.
Signed-off-by: Li Nan <linan122@huawei.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20240117031946.2324519-3-linan666@huaweicloud.comSigned-off-by: Song Liu <song@kernel.org>