Re: [PATCHv2 4/5] nvme: use return value from blk_execute_rq()

Christoph Hellwig
2021-04-26T14:46:57Z

On Fri, Apr 23, 2021 at 03:05:57PM -0700, Keith Busch wrote:
> We don't have an nvme status to report if the driver's .queue_rq()
> returns an error without dispatching the requested nvme command. Use the
> return value from blk_execute_rq() for all passthrough commands so the
> caller may know their command was not successful.
>
> If the command is from the target passthrough interface and fails to
> dispatch, synthesize the response back to the host as a internal target
> error.
>
> Signed-off-by: Keith Busch <kbusch@kernel.org>
> ---
> drivers/nvme/host/core.c | 16 ++++++++++++----
> drivers/nvme/host/ioctl.c | 6 +-----
> drivers/nvme/host/nvme.h | 2 +-
> drivers/nvme/target/passthru.c | 8 ++++----
> 4 files changed, 18 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
> index 10bb8406e067..62af5fe7a0ce 100644
> --- a/drivers/nvme/host/core.c
> +++ b/drivers/nvme/host/core.c
> @@ -972,12 +972,12 @@ int __nvme_submit_sync_cmd(struct request_queue *q, struct nvme_command *cmd,
> goto out;
> }
>
> - blk_execute_rq(NULL, req, at_head);
> + ret = blk_execute_rq(NULL, req, at_head);
> if (result)
> *result = nvme_req(req)->result;
> if (nvme_req(req)->flags & NVME_REQ_CANCELLED)
> ret = -EINTR;
> - else
> + else if (nvme_req(req)->status)
> ret = nvme_req(req)->status;

Just cosmetic, and already in the existing code, but I'd prefer if we
could keep the ret assignments together, something like:

status = blk_execute_rq(NULL, req, at_head);
if (nvme_req(req)->flags & NVME_REQ_CANCELLED)
ret = -EINTR;
else if (nvme_req(req)->status)
ret = nvme_req(req)->status;
else
ret = blk_status_to_errno(status);

if (result)
*result = nvme_req(req)->result;

> + ret = blk_execute_rq(disk, rq, 0);
> if (effects) /* nothing to be done for zero cmd effects */
> nvme_passthru_end(ctrl, effects);
> +
> + if (nvme_req(rq)->flags & NVME_REQ_CANCELLED)
> + ret = -EINTR;
> + else if (nvme_req(rq)->status)
> + ret = nvme_req(rq)->status;
> +

I think we want a helper for all this return value magic instead of
duplicating it.