[PATCH V3 1/2] io_uring: retain top 8bits of uring_cmd flags for kernel internal use

[Ming Lei <ming.lei@redhat.com>]

Retain top 8bits of uring_cmd flags for kernel internal use, so that we
can move IORING_URING_CMD_POLLED out of uapi header.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 include/linux/io_uring.h      | 3 +++
 include/uapi/linux/io_uring.h | 5 ++---
 io_uring/uring_cmd.c          | 2 +-
 3 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/include/linux/io_uring.h b/include/linux/io_uring.h
index 106cdc55ff3b..ae08d6f66e62 100644
--- a/include/linux/io_uring.h
+++ b/include/linux/io_uring.h
@@ -22,6 +22,9 @@ enum io_uring_cmd_flags {
 	IO_URING_F_IOPOLL		= (1 << 10),
 };
 
+/* only top 8 bits of sqe->uring_cmd_flags for kernel internal use */
+#define IORING_URING_CMD_POLLED		(1U << 31)
+
 struct io_uring_cmd {
 	struct file	*file;
 	const struct io_uring_sqe *sqe;
diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index 8e61f8b7c2ce..4df2f11f264f 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -246,13 +246,12 @@ enum io_uring_op {
 };
 
 /*
- * sqe->uring_cmd_flags
+ * sqe->uring_cmd_flags		top 8bits aren't available for userspace
  * IORING_URING_CMD_FIXED	use registered buffer; pass this flag
  *				along with setting sqe->buf_index.
- * IORING_URING_CMD_POLLED	driver use only
  */
 #define IORING_URING_CMD_FIXED	(1U << 0)
-#define IORING_URING_CMD_POLLED	(1U << 31)
+#define IORING_URING_CMD_MASK	0x00ffffffU
 
 
 /*
diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c
index 537795fddc87..52a455b67163 100644
--- a/io_uring/uring_cmd.c
+++ b/io_uring/uring_cmd.c
@@ -90,7 +90,7 @@ int io_uring_cmd_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 	if (sqe->__pad1)
 		return -EINVAL;
 
-	ioucmd->flags = READ_ONCE(sqe->uring_cmd_flags);
+	ioucmd->flags = READ_ONCE(sqe->uring_cmd_flags) & IORING_URING_CMD_MASK;
 	if (ioucmd->flags & ~IORING_URING_CMD_FIXED)
 		return -EINVAL;
 
-- 
2.41.0