null_blk: fix softirq completions for queue_mode == 1

Only blk-mq completions have payload attached to the request, for
request_fn mode we have stored it in req->special. This fixes an
oops with queue_mode=1 and softirq completions.

Signed-off-by: Jens Axboe <axboe@fb.com>

1 files changed, 4 insertions, 1 deletions

diff --git a/drivers/block/null_blk.c b/drivers/block/null_blk.c
index f87c4c4c1c41..a3b042c4d448 100644
--- a/drivers/block/null_blk.c
+++ b/drivers/block/null_blk.c
@@ -227,7 +227,10 @@ static void null_cmd_end_timer(struct nullb_cmd *cmd)
 
 static void null_softirq_done_fn(struct request *rq)
 {
-        end_cmd(blk_mq_rq_to_pdu(rq));
+        if (queue_mode == NULL_Q_MQ)
+                end_cmd(blk_mq_rq_to_pdu(rq));
+        else
+                end_cmd(rq->special);
 }
 
 static inline void null_handle_cmd(struct nullb_cmd *cmd)