[PATCH 6/8] io_uring/nop: add support for IORING_SETUP_CQE_MIXED

[Jens Axboe <axboe@kernel.dk>]

This adds support for setting IORING_NOP_CQE32 as a flag for a NOP
command, in which case a 32b CQE will be posted rather than a regular
one. This is the default if the ring has been setup with
IORING_SETUP_CQE32. If the ring has been setup with
IORING_SETUP_CQE_MIXED, then 16b CQEs will be posted without this flag
set, and 32b CQEs if this flag is set. For the latter case, sqe->off is
what will be posted as cqe->big_cqe[0] and sqe->addr is what will be
posted as cqe->big_cqe[1].

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 include/uapi/linux/io_uring.h |  1 +
 io_uring/nop.c                | 17 +++++++++++++++--
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index 9396afb01dc8..33b386f43d47 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -460,6 +460,7 @@ enum io_uring_msg_ring_flags {
 #define IORING_NOP_FIXED_FILE		(1U << 2)
 #define IORING_NOP_FIXED_BUFFER		(1U << 3)
 #define IORING_NOP_TW			(1U << 4)
+#define IORING_NOP_CQE32		(1U << 5)
 
 /*
  * IO completion data structure (Completion Queue Entry)
diff --git a/io_uring/nop.c b/io_uring/nop.c
index 20ed0f85b1c2..3caf07878f8a 100644
--- a/io_uring/nop.c
+++ b/io_uring/nop.c
@@ -17,11 +17,13 @@ struct io_nop {
 	int             result;
 	int		fd;
 	unsigned int	flags;
+	__u64		extra1;
+	__u64		extra2;
 };
 
 #define NOP_FLAGS	(IORING_NOP_INJECT_RESULT | IORING_NOP_FIXED_FILE | \
 			 IORING_NOP_FIXED_BUFFER | IORING_NOP_FILE | \
-			 IORING_NOP_TW)
+			 IORING_NOP_TW | IORING_NOP_CQE32)
 
 int io_nop_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 {
@@ -41,6 +43,14 @@ int io_nop_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 		nop->fd = -1;
 	if (nop->flags & IORING_NOP_FIXED_BUFFER)
 		req->buf_index = READ_ONCE(sqe->buf_index);
+	if (nop->flags & IORING_NOP_CQE32) {
+		struct io_ring_ctx *ctx = req->ctx;
+
+		if (!(ctx->flags & (IORING_SETUP_CQE32|IORING_SETUP_CQE_MIXED)))
+			return -EINVAL;
+		nop->extra1 = READ_ONCE(sqe->off);
+		nop->extra2 = READ_ONCE(sqe->addr);
+	}
 	return 0;
 }
 
@@ -68,7 +78,10 @@ int io_nop(struct io_kiocb *req, unsigned int issue_flags)
 done:
 	if (ret < 0)
 		req_set_fail(req);
-	io_req_set_res(req, nop->result, 0);
+	if (nop->flags & IORING_NOP_CQE32)
+		io_req_set_res32(req, nop->result, 0, nop->extra1, nop->extra2);
+	else
+		io_req_set_res(req, nop->result, 0);
 	if (nop->flags & IORING_NOP_TW) {
 		req->io_task_work.func = io_req_task_complete;
 		io_req_task_work_add(req);
-- 
2.50.1