[dm-devel] [PATCH] block: Improve io_opt limit stacking

[Martin K. Petersen]

>>> +	if (t->io_opt & (t->physical_block_size - 1))
>>> +		t->io_opt = lcm(t->io_opt, t->physical_block_size);
>
>> Any comment on this patch ?  Note: the patch the patch "nvme: Fix
>> io_opt limit setting" is already queued for 5.8.
>
> Setting io_opt to the physical block size is not correct.

Oh, missed the lcm(). But I'm still concerned about twiddling io_opt to
a value different than the one reported by an underlying device.

Setting io_opt to something that's less than a full stripe width in a
RAID, for instance, doesn't produce the expected result. So I think I'd
prefer not to set io_opt at all if it isn't consistent across all the
stacked devices.

Let me chew on it for a bit...

-- 
Martin K. Petersen	Oracle Linux Engineering