[PATCH V2 2/2] blk-mq: make sure elevator callbacks aren't called for passthrough request

[Ming Lei <ming.lei@xxxxxxxxxx>]

In case of q->elevator, passthrought request can still be marked as RQF_ELV,
so some elevator callbacks will be called for passthrough request.

Add helper of blk_mq_bypass_sched(), so that we can bypass elevator
callbacks for both flush and passthrough request.

Suggested-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
---
 block/blk-mq-sched.h | 9 +++++++--
 block/blk-mq.c       | 5 ++---
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/block/blk-mq-sched.h b/block/blk-mq-sched.h
index 7c3cbad17f30..4aa879749843 100644
--- a/block/blk-mq-sched.h
+++ b/block/blk-mq-sched.h
@@ -22,6 +22,11 @@ int blk_mq_init_sched(struct request_queue *q, struct elevator_type *e);
 void blk_mq_exit_sched(struct request_queue *q, struct elevator_queue *e);
 void blk_mq_sched_free_rqs(struct request_queue *q);
 
+static inline bool blk_mq_bypass_sched(blk_opf_t cmd_flags)
+{
+	return op_is_flush(cmd_flags) || blk_op_is_passthrough(cmd_flags);
+}
+
 static inline void blk_mq_sched_restart(struct blk_mq_hw_ctx *hctx)
 {
 	if (test_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state))
@@ -48,7 +53,7 @@ blk_mq_sched_allow_merge(struct request_queue *q, struct request *rq,
 
 static inline void blk_mq_sched_completed_request(struct request *rq, u64 now)
 {
-	if (rq->rq_flags & RQF_ELV) {
+	if ((rq->rq_flags & RQF_ELV) && !blk_mq_bypass_sched(rq->cmd_flags)) {
 		struct elevator_queue *e = rq->q->elevator;
 
 		if (e->type->ops.completed_request)
@@ -58,7 +63,7 @@ static inline void blk_mq_sched_completed_request(struct request *rq, u64 now)
 
 static inline void blk_mq_sched_requeue_request(struct request *rq)
 {
-	if (rq->rq_flags & RQF_ELV) {
+	if ((rq->rq_flags & RQF_ELV) && !blk_mq_bypass_sched(rq->cmd_flags)) {
 		struct request_queue *q = rq->q;
 		struct elevator_queue *e = q->elevator;
 
diff --git a/block/blk-mq.c b/block/blk-mq.c
index b4aaf42f1125..bd80fe3aa0c3 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -392,7 +392,7 @@ static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data,
 		INIT_HLIST_NODE(&rq->hash);
 		RB_CLEAR_NODE(&rq->rb_node);
 
-		if (!op_is_flush(data->cmd_flags) &&
+		if (!blk_mq_bypass_sched(data->cmd_flags) &&
 		    e->type->ops.prepare_request) {
 			e->type->ops.prepare_request(rq);
 			rq->rq_flags |= RQF_ELVPRIV;
@@ -458,8 +458,7 @@ static struct request *__blk_mq_alloc_requests(struct blk_mq_alloc_data *data)
 		 * dispatch list. Don't include reserved tags in the
 		 * limiting, as it isn't useful.
 		 */
-		if (!op_is_flush(data->cmd_flags) &&
-		    !blk_op_is_passthrough(data->cmd_flags) &&
+		if (!blk_mq_bypass_sched(data->cmd_flags) &&
 		    e->type->ops.limit_depth &&
 		    !(data->flags & BLK_MQ_REQ_RESERVED))
 			e->type->ops.limit_depth(data->cmd_flags, data);
-- 
2.40.1