On Mon, Dec 17, 2018 at 09:00:52AM +0800, Ming Lei wrote: > On Sun, Dec 16, 2018 at 05:11:59PM +0100, Christoph Hellwig wrote: > > On Sun, Dec 16, 2018 at 10:25:14AM +0800, Ming Lei wrote: > > > If we don't have poll queue, its mapping should share default type's, > > > instead of setting up one new mapping via blk_mq_map_queues(). > > > > No, if we don't have poll queues nr_maps should be 2. I've already > > posted a patch for that for nvme-pci which got it wrong (my fault..) > > This patch doesn't touch nr_maps. > > The issue is that if poll_queues/write_queues are zero, all three mapping > should be same, however they aren't actually because we still use blk_mq_map_queues() > to build a new mapping for poll queue. In Jens' for-4.21 we only support polling with explicit poll queues, and thus an explicit poll map. Which means nr_maps must be 3 if you support poll maps, and < 3 if you don't. As said, the only user actually got that wrong (my fault), but the fix is already queue up in the nvme tree and on its way to Jens.
