[PATCH 2/2] nvme/ioctl: call io_uring_cmd_set_res32() in ->end_io()

[Caleb Sander Mateos]

io_uring_cmd_set_res32() only performs loads and stores to the io_uring
request state, so it's safe to call in interrupt context. Move the call
from the nvme_uring_task_cb() task work to nvme_uring_cmd_end_io(). This
unifies the 2 io_uring_cmd_set_res32() callers and removes the need to
pass result and status through struct nvme_uring_cmd_pdu, saving 16
bytes and a couple memory accesses.

Signed-off-by: Caleb Sander Mateos <csander at purestorage.com>
---
 drivers/nvme/host/ioctl.c | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/drivers/nvme/host/ioctl.c b/drivers/nvme/host/ioctl.c
index 131959c00287..b50bba207818 100644
--- a/drivers/nvme/host/ioctl.c
+++ b/drivers/nvme/host/ioctl.c
@@ -421,12 +421,10 @@ struct nvme_uring_data {
  * Expect build errors if this grows larger than that.
  */
 struct nvme_uring_cmd_pdu {
 	struct request *req;
 	struct bio *bio;
-	u64 result;
-	int status;
 };
 
 static inline struct nvme_uring_cmd_pdu *nvme_uring_cmd_pdu(
 		struct io_uring_cmd *ioucmd)
 {
@@ -438,29 +436,30 @@ static void nvme_uring_task_cb(struct io_tw_req tw_req, io_tw_token_t tw)
 	struct io_uring_cmd *ioucmd = io_uring_cmd_from_tw(tw_req);
 	struct nvme_uring_cmd_pdu *pdu = nvme_uring_cmd_pdu(ioucmd);
 
 	if (pdu->bio)
 		blk_rq_unmap_user(pdu->bio);
-	io_uring_cmd_set_res32(ioucmd, pdu->status, pdu->result);
 	io_uring_cmd_done(ioucmd, IO_URING_CMD_TASK_WORK_ISSUE_FLAGS);
 }
 
 static enum rq_end_io_ret nvme_uring_cmd_end_io(struct request *req,
 						blk_status_t err,
 						const struct io_comp_batch *iob)
 {
 	struct io_uring_cmd *ioucmd = req->end_io_data;
 	struct nvme_uring_cmd_pdu *pdu = nvme_uring_cmd_pdu(ioucmd);
+	u64 result = le64_to_cpu(nvme_req(req)->result.u64);
+	int status;
 
 	if (nvme_req(req)->flags & NVME_REQ_CANCELLED) {
-		pdu->status = -EINTR;
+		status = -EINTR;
 	} else {
-		pdu->status = nvme_req(req)->status;
-		if (!pdu->status)
-			pdu->status = blk_status_to_errno(err);
+		status = nvme_req(req)->status;
+		if (!status)
+			status = blk_status_to_errno(err);
 	}
-	pdu->result = le64_to_cpu(nvme_req(req)->result.u64);
+	io_uring_cmd_set_res32(ioucmd, status, result);
 
 	/*
 	 * For IOPOLL, check if this completion is happening in the context
 	 * of the same io_ring that owns the request (local context). If so,
 	 * we can complete inline without task_work overhead. Otherwise, we
@@ -469,11 +468,10 @@ static enum rq_end_io_ret nvme_uring_cmd_end_io(struct request *req,
 	 */
 	if (blk_rq_is_poll(req) && iob &&
 	    iob->poll_ctx == io_uring_cmd_ctx_handle(ioucmd)) {
 		if (pdu->bio)
 			blk_rq_unmap_user(pdu->bio);
-		io_uring_cmd_set_res32(ioucmd, pdu->status, pdu->result);
 		io_uring_cmd_done(ioucmd, 0);
 	} else {
 		io_uring_cmd_do_in_task_lazy(ioucmd, nvme_uring_task_cb);
 	}
 	return RQ_END_IO_FREE;
-- 
2.55.0