On Thu, 24 Sep 2020, Mike Snitzer wrote:
> WAIT... Could it be that raid_io_hints _really_ meant to special case
> raid0 and raid10 -- due to their striping/splitting requirements!?
> So, not raid1 but raid0?
>
> E.g.:
>
> diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c
> index 56b723d012ac..6dca932d6f1d 100644
> --- a/drivers/md/dm-raid.c
> +++ b/drivers/md/dm-raid.c
> @@ -3730,10 +3730,10 @@ static void raid_io_hints(struct dm_target *ti,
> struct queue_limits *limits)
> blk_limits_io_opt(limits, chunk_size_bytes *
> mddev_data_stripes(rs));
>
> /*
> - * RAID1 and RAID10 personalities require bio splitting,
> - * RAID0/4/5/6 don't and process large discard bios properly.
> + * RAID0 and RAID10 personalities require bio splitting,
> + * RAID1/4/5/6 don't and process large discard bios properly.
> */
> - if (rs_is_raid1(rs) || rs_is_raid10(rs)) {
> + if (rs_is_raid0(rs) || rs_is_raid10(rs)) {
> limits->discard_granularity = chunk_size_bytes;
> limits->max_discard_sectors = rs->md.chunk_sectors;
> }
>
> Mike
Yes - that's an interesing point.
Mikulas
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