On 10/4/22 09:11, Hannes Reinecke wrote:
On 10/3/22 11:43, Sagi Grimberg wrote:Our mpath stack device is just a shim that selects a bottom namespace and submits the bio to it without any fancy splitting. This also means that we don't clone the bio or have any context to the bio beyond submission. However it really sucks that we don't see the mpath device io stats. Given that the mpath device can't do that without adding some context to it, we let the bottom device do it on its behalf (somewhat similar to the approach taken in nvme_trace_bio_complete). When the IO starts, we account the request for multipath IO stats using REQ_NVME_MPATH_IO_STATS nvme_request flag to avoid queue io stats disable in the middle of the request. Signed-off-by: Sagi Grimberg <sagi@xxxxxxxxxxx> --- drivers/nvme/host/core.c | 4 ++++ drivers/nvme/host/multipath.c | 25 +++++++++++++++++++++++++ drivers/nvme/host/nvme.h | 12 ++++++++++++ 3 files changed, 41 insertions(+) diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c index 64fd772de817..d5a54ddf73f2 100644 --- a/drivers/nvme/host/core.c +++ b/drivers/nvme/host/core.c @@ -384,6 +384,8 @@ static inline void nvme_end_req(struct request *req) nvme_log_error(req); nvme_end_req_zoned(req); nvme_trace_bio_complete(req); + if (req->cmd_flags & REQ_NVME_MPATH) + nvme_mpath_end_request(req); blk_mq_end_request(req, status); } @@ -421,6 +423,8 @@ EXPORT_SYMBOL_GPL(nvme_complete_rq); void nvme_start_request(struct request *rq) { + if (rq->cmd_flags & REQ_NVME_MPATH) + nvme_mpath_start_request(rq); blk_mq_start_request(rq); } EXPORT_SYMBOL_GPL(nvme_start_request);Why don't you move the check for REQ_NVME_MPATH into nvme_mpath_{start,end}_request?
I'm less fond of calling a function that may or may not do anything... But it is a pattern that exists in the code, if people prefer it I can change it.
