From: Ming Lei <ming.lei@xxxxxxxxxx>
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@xxxxxxxxxxxxxxx
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
---
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;
--
2.15.0
