io_uring: retain top 8bits of uring_cmd flags for kernel internal use

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

Reviewed-by: Gabriel Krisman Bertazi <krisman@suse.de>
Reviewed-by: Anuj Gupta <anuj20.g@samsung.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/include/linux/io_uring.h b/include/linux/io_uring.h
index 106cdc5..ae08d6f 100644 (file)
--- 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 683ac2b..425f64e 100644 (file)
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -249,13 +249,12 @@ 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 2dff477..cb6bd99 100644 (file)
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -4669,6 +4669,9 @@ 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 537795f..a0b0ec5 100644 (file)
--- 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) {