Re: [PATCH 4/5] nvme: Fail dead namespace's entered requests

[Keith Busch <keith.busch@intel.com>]

On Fri, Mar 08, 2019 at 10:15:27AM -0800, Bart Van Assche wrote:
> On Fri, 2019-03-08 at 10:40 -0700, Keith Busch wrote:
> > End the entered requests on a quieced queue directly rather than flush
> > them through the low level driver's queue_rq().
> > 
> > Signed-off-by: Keith Busch <keith.busch@intel.com>
> > ---
> >  drivers/nvme/host/core.c | 10 ++++++++--
> >  1 file changed, 8 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
> > index cc5d9a83d5af..7095406bb293 100644
> > --- a/drivers/nvme/host/core.c
> > +++ b/drivers/nvme/host/core.c
> > @@ -94,6 +94,13 @@ static void nvme_put_subsystem(struct nvme_subsystem *subsys);
> >  static void nvme_remove_invalid_namespaces(struct nvme_ctrl *ctrl,
> >  					   unsigned nsid);
> >  
> > +static bool nvme_fail_request(struct blk_mq_hw_ctx *hctx, struct request *req,
> > +			      void *data, bool reserved)
> > +{
> > +	blk_mq_end_request(req, BLK_STS_IOERR);
> > +	return true;
> > +}
> 
> Calling blk_mq_end_request() from outside the .queue_rq() or .complete()
> callback functions is wrong. Did you perhaps want to call
> blk_mq_complete_request()?

This callback can only see requests in MQ_RQ_IDLE state, and
bkl_mq_end_request() is the correct way to end those that never entered
a driver's queue_rq().