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().

Fixes: 3c94d83cb3526 ("blk-mq: change blk_mq_queue_busy() to blk_mq_queue_inflight()") Cc: stable@vger.kernel.org Signed-off-by: Ming Lei ming.lei@redhat.com Signed-off-by: Mike Snitzer snitzer@redhat.com --- block/blk-mq.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c index 4f57d27bfa73..e6219c27fc65 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -828,10 +828,10 @@ static bool blk_mq_rq_inflight(struct blk_mq_hw_ctx *hctx, struct request *rq, void *priv, bool reserved) { /* - * If we find a request that is inflight and the queue matches, + * If we find a request that isn't idle and the queue matches, * we know the queue is busy. Return false to stop the iteration. */ - if (rq->state == MQ_RQ_IN_FLIGHT && rq->q == hctx->queue) { + if (blk_mq_request_started(rq) && rq->q == hctx->queue) { bool *busy = priv;

*busy = true;