Re: [PATCH v2] nvme: fix multipath crash caused by flush request when blktrace is enabled

[Christoph Hellwig <hch@xxxxxx>]

Just checking for ->bio seems to be:

 - simpler
 - faster

and does not require block layer internals.  So why not just this:


diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 6bbb73ef8b2548..424c8a467a0c2a 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -893,7 +893,7 @@ static inline void nvme_trace_bio_complete(struct request *req)
 {
 	struct nvme_ns *ns = req->q->queuedata;
 
-	if (req->cmd_flags & REQ_NVME_MPATH)
+	if ((req->cmd_flags & REQ_NVME_MPATH) && req->bio)
 		trace_block_bio_complete(ns->head->disk->queue, req->bio);
 }