io_uring: support to inject result for NOP

Support to inject result for NOP so that we can inject failure from
userspace. It is very helpful for covering failure handling code in
io_uring core change.

With nop flags, it becomes possible to add more test features on NOP in
future.

Suggested-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20240510035031.78874-3-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index 6dbac55f86861b6ec0683bd97bb6634fc4fcd077..994bf7af0efe20afbfc4888413ad5a6d261a0e6e 100644 (file)
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -72,6 +72,7 @@ struct io_uring_sqe {
                __u32           waitid_flags;
                __u32           futex_flags;
                __u32           install_fd_flags;
+               __u32           nop_flags;
        };
        __u64   user_data;      /* data to be passed back at completion time */
        /* pack this to avoid bogus arm OABI complaints */
@@ -407,6 +408,13 @@ enum io_uring_msg_ring_flags {
  */
 #define IORING_FIXED_FD_NO_CLOEXEC     (1U << 0)
 
+/*
+ * IORING_OP_NOP flags (sqe->nop_flags)
+ *
+ * IORING_NOP_INJECT_RESULT    Inject result from sqe->result
+ */
+#define IORING_NOP_INJECT_RESULT       (1U << 0)
+
 /*
  * IO completion data structure (Completion Queue Entry)
  */

diff --git a/io_uring/nop.c b/io_uring/nop.c
index 1a4e312dfe510af0c54f8d5243ef4a01926dbb53..a5bcf3d6984f7be6e5d4d9ac0adb5f34fdfe8276 100644 (file)
--- a/io_uring/nop.c
+++ b/io_uring/nop.c
@@ -10,18 +10,34 @@
 #include "io_uring.h"
 #include "nop.h"
 
+struct io_nop {
+       /* NOTE: kiocb has the file as the first member, so don't do it here */
+       struct file     *file;
+       int             result;
+};
+
 int io_nop_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 {
-       if (READ_ONCE(sqe->rw_flags))
+       unsigned int flags;
+       struct io_nop *nop = io_kiocb_to_cmd(req, struct io_nop);
+
+       flags = READ_ONCE(sqe->nop_flags);
+       if (flags & ~IORING_NOP_INJECT_RESULT)
                return -EINVAL;
+
+       if (flags & IORING_NOP_INJECT_RESULT)
+               nop->result = READ_ONCE(sqe->len);
+       else
+               nop->result = 0;
        return 0;
 }
 
-/*
- * IORING_OP_NOP just posts a completion event, nothing else.
- */
 int io_nop(struct io_kiocb *req, unsigned int issue_flags)
 {
-       io_req_set_res(req, 0, 0);
+       struct io_nop *nop = io_kiocb_to_cmd(req, struct io_nop);
+
+       if (nop->result < 0)
+               req_set_fail(req);
+       io_req_set_res(req, nop->result, 0);
        return IOU_OK;
 }