[PATCH 3/6] liburing.h: add api to support multishot accept direct

[Hao Xu <haoxu.linux@gmail.com>]

From: Hao Xu <howeyxu@tencent.com>

This is to support the multishot accept directly to the fixed table, the
file_Index should be set to IORING_FILE_INDEX_ALLOC in this case.

Signed-off-by: Hao Xu <howeyxu@tencent.com>
---
 src/include/liburing.h          | 11 +++++++++++
 src/include/liburing/io_uring.h |  9 +++++++++
 2 files changed, 20 insertions(+)

diff --git a/src/include/liburing.h b/src/include/liburing.h
index cf50383c8e63..9065555d39f4 100644
--- a/src/include/liburing.h
+++ b/src/include/liburing.h
@@ -512,6 +512,17 @@ static inline void io_uring_prep_multishot_accept(struct io_uring_sqe *sqe,
 	sqe->ioprio |= IORING_ACCEPT_MULTISHOT;
 }
 
+/* multishot accept directly into the fixed file table */
+static inline void io_uring_prep_multishot_accept_direct(struct io_uring_sqe *sqe,
+							 int fd,
+							 struct sockaddr *addr,
+							 socklen_t *addrlen,
+							 int flags)
+{
+	io_uring_prep_multishot_accept(sqe, fd, addr, addrlen, flags);
+	__io_uring_set_target_fixed_file(sqe, IORING_FILE_INDEX_ALLOC - 1);
+}
+
 static inline void io_uring_prep_cancel(struct io_uring_sqe *sqe,
 					__u64 user_data, int flags)
 {
diff --git a/src/include/liburing/io_uring.h b/src/include/liburing/io_uring.h
index 46765d2697ba..6260e0d1f4ef 100644
--- a/src/include/liburing/io_uring.h
+++ b/src/include/liburing/io_uring.h
@@ -67,6 +67,15 @@ struct io_uring_sqe {
 	__u64	__pad2[2];
 };
 
+/*
+ * If sqe->file_index is set to this for opcodes that instantiate a new
+ * direct descriptor (like openat/openat2/accept), then io_uring will allocate
+ * an available direct descriptor instead of having the application pass one
+ * in. The picked direct descriptor will be returned in cqe->res, or -ENFILE
+ * if the space is full.
+ */
+#define IORING_FILE_INDEX_ALLOC         (~0U)
+
 enum {
 	IOSQE_FIXED_FILE_BIT,
 	IOSQE_IO_DRAIN_BIT,
-- 
2.36.0