Re: [PATCHv2 3/5] nvme: unify nvme request end_io

[Kanchan Joshi <joshi.k@samsung.com>]

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On Fri, Apr 07, 2023 at 12:16:34PM -0700, Keith Busch wrote:
>From: Keith Busch <kbusch@kernel.org>
>
>We can finish the metadata copy inline with the completion. After that,
>there's really nothing else different between the meta and non-meta data
>end_io callbacks, so unify them.
>
>Signed-off-by: Keith Busch <kbusch@kernel.org>
>---
> drivers/nvme/host/ioctl.c | 57 +++++++--------------------------------
> 1 file changed, 9 insertions(+), 48 deletions(-)
>
>diff --git a/drivers/nvme/host/ioctl.c b/drivers/nvme/host/ioctl.c
>index 278c57ee0db91..a1e0a14dadedc 100644
>--- a/drivers/nvme/host/ioctl.c
>+++ b/drivers/nvme/host/ioctl.c
>@@ -465,29 +465,6 @@ static inline struct nvme_uring_cmd_pdu *nvme_uring_cmd_pdu(
> 	return (struct nvme_uring_cmd_pdu *)&ioucmd->pdu;
> }
>
>-static void nvme_uring_task_meta_cb(struct io_uring_cmd *ioucmd,
>-				    unsigned issue_flags)
>-{
>-	struct nvme_uring_cmd_pdu *pdu = nvme_uring_cmd_pdu(ioucmd);
>-	struct request *req = pdu->req;
>-	int status;
>-	u64 result;
>-
>-	if (nvme_req(req)->flags & NVME_REQ_CANCELLED)
>-		status = -EINTR;
>-	else
>-		status = nvme_req(req)->status;
>-
>-	result = le64_to_cpu(nvme_req(req)->result.u64);
>-
>-	if (pdu->meta_len)
>-		status = nvme_finish_user_metadata(req, pdu->u.meta_buffer,
>-					pdu->u.meta, pdu->meta_len, status);
>-	blk_mq_free_request(req);
>-
>-	io_uring_cmd_done(ioucmd, status, result, issue_flags);
>-}
>-
> static void nvme_uring_task_cb(struct io_uring_cmd *ioucmd,
> 			       unsigned issue_flags)
> {
>@@ -502,11 +479,16 @@ static enum rq_end_io_ret nvme_uring_cmd_end_io(struct request *req,
> 	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);
>+	int status = nvme_req(req)->status;
>
> 	if (nvme_req(req)->flags & NVME_REQ_CANCELLED)
>-		pdu->nvme_status = -EINTR;
>-	else
>-		pdu->nvme_status = nvme_req(req)->status;
>+		status = -EINTR;
>+
>+	if (pdu->meta_len)
>+		status = nvme_finish_user_metadata(req, pdu->u.meta_buffer,
>+					pdu->u.meta, pdu->meta_len, status);

nvme_finish_user_metadata does copy_to_user.
Here also the attempt was not to touch that memory in interrupt context.

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