[PATCH 4/5] nvme: split out metadata vs non metadata end_io uring_cmd completions

[Anuj gupta]

On Tue, Sep 27, 2022 at 7:22 AM Jens Axboe <axboe at kernel.dk> wrote:
>
> By splitting up the metadata and non-metadata end_io handling, we can
> remove any request dependencies on the normal non-metadata IO path. This
> is in preparation for enabling the normal IO passthrough path to pass
> the ownership of the request back to the block layer.
>
> Co-developed-by: Stefan Roesch <shr at fb.com>
> Signed-off-by: Jens Axboe <axboe at kernel.dk>
> ---
>  drivers/nvme/host/ioctl.c | 79 ++++++++++++++++++++++++++++++---------
>  1 file changed, 61 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/nvme/host/ioctl.c b/drivers/nvme/host/ioctl.c
> index c80b3ecca5c8..9e356a6c96c2 100644
> --- a/drivers/nvme/host/ioctl.c
> +++ b/drivers/nvme/host/ioctl.c
> @@ -349,9 +349,15 @@ struct nvme_uring_cmd_pdu {
>                 struct bio *bio;
>                 struct request *req;
>         };
> -       void *meta; /* kernel-resident buffer */
> -       void __user *meta_buffer;
>         u32 meta_len;
> +       u32 nvme_status;
> +       union {
> +               struct {
> +                       void *meta; /* kernel-resident buffer */
> +                       void __user *meta_buffer;
> +               };
> +               u64 result;
> +       } u;
>  };
>
>  static inline struct nvme_uring_cmd_pdu *nvme_uring_cmd_pdu(
> @@ -360,11 +366,10 @@ static inline struct nvme_uring_cmd_pdu *nvme_uring_cmd_pdu(
>         return (struct nvme_uring_cmd_pdu *)&ioucmd->pdu;
>  }
>
> -static void nvme_uring_task_cb(struct io_uring_cmd *ioucmd)
> +static void nvme_uring_task_meta_cb(struct io_uring_cmd *ioucmd)
>  {
>         struct nvme_uring_cmd_pdu *pdu = nvme_uring_cmd_pdu(ioucmd);
>         struct request *req = pdu->req;
> -       struct bio *bio = req->bio;
>         int status;
>         u64 result;
>
> @@ -375,27 +380,39 @@ static void nvme_uring_task_cb(struct io_uring_cmd *ioucmd)
>
>         result = le64_to_cpu(nvme_req(req)->result.u64);
>
> -       if (pdu->meta)
> -               status = nvme_finish_user_metadata(req, pdu->meta_buffer,
> -                                       pdu->meta, pdu->meta_len, status);
> -       if (bio)
> -               blk_rq_unmap_user(bio);
> +       if (pdu->meta_len)
> +               status = nvme_finish_user_metadata(req, pdu->u.meta_buffer,
> +                                       pdu->u.meta, pdu->meta_len, status);
> +       if (req->bio)
> +               blk_rq_unmap_user(req->bio);
>         blk_mq_free_request(req);
>
>         io_uring_cmd_done(ioucmd, status, result);
>  }
>
> +static void nvme_uring_task_cb(struct io_uring_cmd *ioucmd)
> +{
> +       struct nvme_uring_cmd_pdu *pdu = nvme_uring_cmd_pdu(ioucmd);
> +
> +       if (pdu->bio)
> +               blk_rq_unmap_user(pdu->bio);
> +
> +       io_uring_cmd_done(ioucmd, pdu->nvme_status, pdu->u.result);
> +}
> +
>  static enum rq_end_io_ret nvme_uring_cmd_end_io(struct request *req,
>                                                 blk_status_t err)
>  {
>         struct io_uring_cmd *ioucmd = req->end_io_data;
>         struct nvme_uring_cmd_pdu *pdu = nvme_uring_cmd_pdu(ioucmd);
> -       /* extract bio before reusing the same field for request */
> -       struct bio *bio = pdu->bio;
>         void *cookie = READ_ONCE(ioucmd->cookie);
>
> -       pdu->req = req;
> -       req->bio = bio;
> +       req->bio = pdu->bio;
> +       if (nvme_req(req)->flags & NVME_REQ_CANCELLED)
> +               pdu->nvme_status = -EINTR;
> +       else
> +               pdu->nvme_status = nvme_req(req)->status;
> +       pdu->u.result = le64_to_cpu(nvme_req(req)->result.u64);
>
>         /*
>          * For iopoll, complete it directly.
> @@ -406,6 +423,29 @@ static enum rq_end_io_ret nvme_uring_cmd_end_io(struct request *req,
>         else
>                 io_uring_cmd_complete_in_task(ioucmd, nvme_uring_task_cb);
>
> +       blk_mq_free_request(req);
> +       return RQ_END_IO_NONE;
> +}
> +
> +static enum rq_end_io_ret nvme_uring_cmd_end_io_meta(struct request *req,
> +                                                    blk_status_t err)
> +{
> +       struct io_uring_cmd *ioucmd = req->end_io_data;
> +       struct nvme_uring_cmd_pdu *pdu = nvme_uring_cmd_pdu(ioucmd);
> +       void *cookie = READ_ONCE(ioucmd->cookie);
> +
> +       req->bio = pdu->bio;
> +       pdu->req = req;
> +
> +       /*
> +        * For iopoll, complete it directly.
> +        * Otherwise, move the completion to task work.
> +        */
> +       if (cookie != NULL && blk_rq_is_poll(req))
> +               nvme_uring_task_meta_cb(ioucmd);
> +       else
> +               io_uring_cmd_complete_in_task(ioucmd, nvme_uring_task_meta_cb);
> +
>         return RQ_END_IO_NONE;
>  }
>
> @@ -467,8 +507,6 @@ static int nvme_uring_cmd_io(struct nvme_ctrl *ctrl, struct nvme_ns *ns,
>                         blk_flags);
>         if (IS_ERR(req))
>                 return PTR_ERR(req);
> -       req->end_io = nvme_uring_cmd_end_io;
> -       req->end_io_data = ioucmd;
>
>         if (issue_flags & IO_URING_F_IOPOLL && rq_flags & REQ_POLLED) {
>                 if (unlikely(!req->bio)) {
> @@ -483,10 +521,15 @@ static int nvme_uring_cmd_io(struct nvme_ctrl *ctrl, struct nvme_ns *ns,
>         }
>         /* to free bio on completion, as req->bio will be null at that time */
>         pdu->bio = req->bio;
> -       pdu->meta = meta;
> -       pdu->meta_buffer = nvme_to_user_ptr(d.metadata);
>         pdu->meta_len = d.metadata_len;
> -
> +       req->end_io_data = ioucmd;
> +       if (pdu->meta_len) {
> +               pdu->u.meta = meta;
> +               pdu->u.meta_buffer = nvme_to_user_ptr(d.metadata);
> +               req->end_io = nvme_uring_cmd_end_io_meta;
> +       } else {
> +               req->end_io = nvme_uring_cmd_end_io;
> +       }
>         blk_execute_rq_nowait(req, false);
>         return -EIOCBQUEUED;
>  }
> --
> 2.35.1
>
Looks good.
Reviewed-by: Anuj Gupta <anuj20.g at samsung.com>

--
Anuj Gupta