On Fri, Jul 14, 2017 at 10:02:06AM -0400, Mike Snitzer wrote: > On Fri, Jul 14 2017 at 3:12am -0400, > Christoph Hellwig <hch@xxxxxx> wrote: > > > Btw, we might want to expedite this to 4.13, a 4.13 now defaults > > to blk-mq for scsi, and this patch would make sure that dm keeps > > on just working with that switch. > > Don't think we need to rush anything in response to that change in > SCSI's default. old .request_fn DM multipath works happily ontop of > blk-mq devices (so long as all paths are blk-mq). You're right. In that case I think we should just skip this series and I'll dust of the patch to just kill the non-mq support for 3.14 if the switch of scsi to default to mq works out for 3.13. > It is just blk-mq DM multipath ontop of old .request_fn paths that is > disallowed in current upstream code. > > But again, I really don't see why we should even want/need to support > that mode... hence my question raised in this RFC. I think this mode makes sense in the long run - to get rid of the legacy request code in dm. But as long as we keep both modes arounds the use for it seems a big questionable indeed.
