Bryan Gurney reported I/O errors when using dm-zoned with a host-managed SMR device. It turns out he was using CFQ, which is the default. Unfortunately, as of v4.16, only the deadline schedulers work well with host-managed SMR devices. This series aatempts to switch the elevator to deadline for those devices. NOTE: I'm not super happy with setting up one iosched and then immediately tearing it down. I'm open to suggestions on better ways to accomplish this goal. [PATCH 1/2] block: __elevator_change: add try_loading parameter [PATCH 2/2] block: default to deadline for host-managed SMR devices
