On Sat, Jan 26 2019 at 6:17am -0500, John Dorminy <jdorminy@xxxxxxxxxx> wrote: > Hi. I have read a bit of DM code and spent an hour reviewing this... I > didn't get to the point of knowing what the right fix for the problem > is, and I may have a wrong understanding, but I have two thoughts > about the patch: > > I don't think this is the right solution for two reasons: > > In the first place, if it's an LVM-only issue, we should fix it only > for device-mapper devices. If this is the right way to fix it, > possibly the way to do that would be to change DM calls to > blk_queue_max_write_same_sectors() to only set the max sectors to more > than 0 if and only if the logical block sizes match. There is no way this is specific to lvm (or DM). It may _seem_ that way because lvm/dm are in the business of creating stacked devices -- whereby exposing users to blk_stack_limits(). I'll have a closer look at this issue, hopefully tomorrow, but Zhang Xiaoxu's proposed fix looks bogus to me. Not disputing there is an issue, just feels like a different fix is needed. Mike
