blk-mq: make blk_mq_alloc_request_hctx() allocate a scheduler request

blk_mq_alloc_request_hctx() allocates a driver request directly, unlike
its blk_mq_alloc_request() counterpart. It also crashes because it
doesn't update the tags->rqs map.

Fix it by making it allocate a scheduler request.

Reported-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Tested-by: Sagi Grimberg <sagi@grimberg.me>

1 files changed, 5 insertions, 6 deletions

diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index 46ca965fff5c..5697b23412a1 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -110,15 +110,14 @@ struct request *blk_mq_sched_get_request(struct request_queue *q,
 					 struct blk_mq_alloc_data *data)
 {
 	struct elevator_queue *e = q->elevator;
-	struct blk_mq_hw_ctx *hctx;
-	struct blk_mq_ctx *ctx;
 	struct request *rq;
 
 	blk_queue_enter_live(q);
-	ctx = blk_mq_get_ctx(q);
-	hctx = blk_mq_map_queue(q, ctx->cpu);
-
-	blk_mq_set_alloc_data(data, q, data->flags, ctx, hctx);
+	data->q = q;
+	if (likely(!data->ctx))
+		data->ctx = blk_mq_get_ctx(q);
+	if (likely(!data->hctx))
+		data->hctx = blk_mq_map_queue(q, data->ctx->cpu);
 
 	if (e) {
 		data->flags |= BLK_MQ_REQ_INTERNAL;