On Mon, Aug 18, 2025 at 11:40:54AM +0800, Yu Kuai wrote: > Then code will be much complex insdie md code, and we'll have to > reimplement the stack limits logical with the consideration if each rdev > is already a stacked rdev. I really do not like this ... You don't. You get the stacked value as input and then simply decide if you want to take it or override it. The easiest way to do the latter is to just stash it away in a local variable before calling queue_limits_stack_bdev and then reapplying it afterwards. > And in theroy, we can't handle this case just in md code: > > scsi disk -> mdarray -> device mapper/loop/nbd ... -> mdarray I don't see how the code in this series could handle that either.