On Fri, 13 Oct 2023 20:12:38 +0800
Xiao Ni [off-list ref] wrote:

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So, it forces the calculations made by Neil back but I think that we can
simply compare dev_size and data_offset between members.  

We don't need to consider the compatibility anymore in future?
 

Not sure if I get your question correctly. This property is supported now so
why we should? It is already there so we are safe to set it.  

I asked because you said we can remove the check in future. So I don't
know why we don't need the check in future. The check here should be
the kernel version check, right?

We are not supporting old kernels forever. At some point of time, we would
decide that kernels older than 5.5 are no longer a valid case and then we will
free to remove verification. If we are not supporting something older than the
version where it was added, we can assume that MD_RAID0_LAYOUT is always
available and we don't need to care anymore, right?

Here a recent example:
https://git.kernel.org/pub/scm/utils/mdadm/mdadm.git/commit/?id=f8d2c4286a

Thanks,
Mariusz