[PATCH v2 1/1] io_uring/net: separate notification user_data

[Pavel Begunkov <asml.silence@gmail.com>]

People previously asked for the notification CQE to have a different
user_data value from the main request completion. It's useful to
separate buffer and request handling logic and avoid separately
refcounting the request.

Introduce a new flag IORING_SEND_ZC_NOTIF_USER_DATA. If set, the
notification user_data will contain the value from sqe->addr3 instead of
inheriting it from the original request.

Note, it doesn't change the rules for when the user can expect a
notification CQE, and it should still check the IORING_CQE_F_MORE flag.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 include/uapi/linux/io_uring.h |  6 ++++++
 io_uring/net.c                | 13 +++++++++++--
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index 6750c383a2ab..e3648147b98e 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -425,6 +425,11 @@ enum io_uring_op {
  *
  * IORING_SEND_VECTORIZED	If set, SEND[_ZC] will take a pointer to a io_vec
  *				to allow vectorized send operations.
+ *
+ * IORING_SEND_ZC_NOTIF_USER_DATA
+ *				If set, the notification CQE user_data will be
+ *				set to the value specified in the addr3 field
+ *				of the SQE.
  */
 #define IORING_RECVSEND_POLL_FIRST	(1U << 0)
 #define IORING_RECV_MULTISHOT		(1U << 1)
@@ -432,6 +437,7 @@ enum io_uring_op {
 #define IORING_SEND_ZC_REPORT_USAGE	(1U << 3)
 #define IORING_RECVSEND_BUNDLE		(1U << 4)
 #define IORING_SEND_VECTORIZED		(1U << 5)
+#define IORING_SEND_ZC_NOTIF_USER_DATA	(1U << 6)
 
 /*
  * cqe.res for IORING_CQE_F_NOTIF if
diff --git a/io_uring/net.c b/io_uring/net.c
index 8576c6cb2236..79c424717f9b 100644
--- a/io_uring/net.c
+++ b/io_uring/net.c
@@ -1317,7 +1317,9 @@ void io_send_zc_cleanup(struct io_kiocb *req)
 	}
 }
 
-#define IO_ZC_FLAGS_COMMON (IORING_RECVSEND_POLL_FIRST | IORING_RECVSEND_FIXED_BUF)
+#define IO_ZC_FLAGS_COMMON (IORING_RECVSEND_POLL_FIRST |\
+			    IORING_RECVSEND_FIXED_BUF |\
+			    IORING_SEND_ZC_NOTIF_USER_DATA)
 #define IO_ZC_FLAGS_VALID  (IO_ZC_FLAGS_COMMON | IORING_SEND_ZC_REPORT_USAGE | \
 				IORING_SEND_VECTORIZED)
 
@@ -1331,7 +1333,7 @@ int io_send_zc_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 
 	zc->done_io = 0;
 
-	if (unlikely(READ_ONCE(sqe->__pad2[0]) || READ_ONCE(sqe->addr3)))
+	if (unlikely(READ_ONCE(sqe->__pad2[0])))
 		return -EINVAL;
 	/* we don't support IOSQE_CQE_SKIP_SUCCESS just yet */
 	if (req->flags & REQ_F_CQE_SKIP)
@@ -1358,6 +1360,13 @@ int io_send_zc_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 		}
 	}
 
+	if (zc->flags & IORING_SEND_ZC_NOTIF_USER_DATA) {
+		notif->cqe.user_data = READ_ONCE(sqe->addr3);
+	} else {
+		if (READ_ONCE(sqe->addr3))
+			return -EINVAL;
+	}
+
 	zc->len = READ_ONCE(sqe->len);
 	zc->msg_flags = READ_ONCE(sqe->msg_flags) | MSG_NOSIGNAL | MSG_ZEROCOPY;
 	req->buf_index = READ_ONCE(sqe->buf_index);
-- 
2.52.0