[PATCH V2 1/4] blk-mq: check rq->state explicitly in blk_mq_tagset_count_completed_rqs

[Ming Lei]

blk_mq_tagset_count_completed_rqs() is called from
blk_mq_tagset_wait_completed_request() for draining requests being
completed remotely. What we need to do is to make sure that request->state
is switched to non-MQ_RQ_COMPLETE.

So check MQ_RQ_COMPLETE explicitly in blk_mq_tagset_count_completed_rqs().

Meantime mark flush request as IDLE in its .end_io() for aligning to
end normal request because flush request may stay in inflight tags in case
of !elevator, so we need to change its state into IDLE.

Cc: Chao Leng <lengchao at huawei.com>
Cc: Sagi Grimberg <sagi at grimberg.me>
Reported-by: Yi Zhang <yi.zhang at redhat.com>
Tested-by: Yi Zhang <yi.zhang at redhat.com>
Signed-off-by: Ming Lei <ming.lei at redhat.com>
---
 block/blk-flush.c  | 2 ++
 block/blk-mq-tag.c | 2 +-
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/block/blk-flush.c b/block/blk-flush.c
index 53abb5c73d99..f6a07ae533c9 100644
--- a/block/blk-flush.c
+++ b/block/blk-flush.c
@@ -231,6 +231,8 @@ static void flush_end_io(struct request *flush_rq, blk_status_t error)
 		return;
 	}
 
+	WRITE_ONCE(flush_rq->state, MQ_RQ_IDLE);
+
 	if (fq->rq_status != BLK_STS_OK)
 		error = fq->rq_status;
 
diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c
index 9c92053e704d..10ff8968b93b 100644
--- a/block/blk-mq-tag.c
+++ b/block/blk-mq-tag.c
@@ -367,7 +367,7 @@ static bool blk_mq_tagset_count_completed_rqs(struct request *rq,
 {
 	unsigned *count = data;
 
-	if (blk_mq_request_completed(rq))
+	if (blk_mq_rq_state(rq) == MQ_RQ_COMPLETE)
 		(*count)++;
 	return true;
 }
-- 
2.25.2