Signed-off-by: Ming Lei <redacted>
---
include/linux/io_uring.h      | 3 +++
include/uapi/linux/io_uring.h | 5 ++---
io_uring/io_uring.c           | 3 +++
io_uring/uring_cmd.c          | 2 +-
4 files changed, 9 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..de77ad08b123 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	IORING_URING_CMD_FIXED


/*

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 783ed0fff71b..9aedb7202403 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c

@@ -4666,6 +4666,9 @@ static int __init io_uring_init(void)

	BUILD_BUG_ON(sizeof(atomic_t) != sizeof(u32));

+	/* top 8bits are for internal use */
+	BUILD_BUG_ON((IORING_URING_CMD_MASK & 0xff000000) != 0);
+
	io_uring_optable_init();

	/*

diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c
index 537795fddc87..a0b0ec5473bf 100644
--- a/io_uring/uring_cmd.c
+++ b/io_uring/uring_cmd.c

@@ -91,7 +91,7 @@ int io_uring_cmd_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)

		return -EINVAL;

	ioucmd->flags = READ_ONCE(sqe->uring_cmd_flags);
-	if (ioucmd->flags & ~IORING_URING_CMD_FIXED)
+	if (ioucmd->flags & ~IORING_URING_CMD_MASK)
		return -EINVAL;

	if (ioucmd->flags & IORING_URING_CMD_FIXED) {
-- 
2.41.0