On 7/7/20 9:04 AM, Mike Snitzer wrote:
From: Ming Lei ming.lei@redhat.com
dm-multipath is the only user of blk_mq_queue_inflight(). When dm-multipath calls blk_mq_queue_inflight() to check if it has outstanding IO it can get a false negative. The reason for this is blk_mq_rq_inflight() doesn't consider requests that are no longer MQ_RQ_IN_FLIGHT but that are now MQ_RQ_COMPLETE (->complete isn't called or finished yet) as "inflight".
This causes request-based dm-multipath's dm_wait_for_completion() to return before all outstanding dm-multipath requests have actually completed. This breaks DM multipath's suspend functionality because blk-mq requests complete after DM's suspend has finished -- which shouldn't happen.
Fix this by considering any request not in the MQ_RQ_IDLE state (so either MQ_RQ_COMPLETE or MQ_RQ_IN_FLIGHT) as "inflight" in blk_mq_rq_inflight().
Applied, thanks.