On Mon, Jan 25 2021 at  7:13am -0500,
Jeffle Xu [off-list ref] wrote:

->poll_fn was introduced in commit ea435e1b9392 ("block: add a poll_fn
callback to struct request_queue") to support bio-based queues such as
nvme multipath, but was later removed in commit 529262d56dbe ("block:
remove ->poll_fn").

Given commit c62b37d96b6e ("block: move ->make_request_fn to struct
block_device_operations") restore the possibility of bio-based IO
polling support by adding an ->iopoll method to gendisk->fops.
Elevate bulk of blk_mq_poll() implementation to blk_poll() and reduce
blk_mq_poll() to blk-mq specific code that is called from blk_poll().

Signed-off-by: Jeffle Xu <jefflexu@linux.alibaba.com>
Suggested-by: Mike Snitzer <redacted>

Reviewed-by: Mike Snitzer <redacted>