io_u: check non-fatal error with IO_U_F_DEVICE_ERROR

IO_U_F_DEVICE_ERROR has been introduced in Commit ebe67b6
("io_uring: Add IO_U_F_DEVICE_ERROR to identify error types") to parse
two different types of errors can happen: (1) device error(e.g.,
NVMe-specific error status code) and (2) system error(e.g., EINVAL).

`--ignore_error=` option let user mask expected situation, but if user
wants to mask system error rather than device error, no way to represent
the system error except for such as -EINVAL.  Even if user put -EINVAL
to the option, it will be checked as a positive value since @io_u->error
will be set with abs() in io_uring_cmd ioengine.

This patch flips the given @io_u->error positive value to a negative
value if the given @io_u->flags represents system error by
IO_U_F_DEVICE_ERROR.

Signed-off-by: Minwoo Im <[email protected]>

Author: minwooim

io_u.c

@@ -2196,7 +2196,16 @@ static void io_completed(struct thread_data *td, struct io_u **io_u_ptr,
 		}
 	} else if (io_u->error) {
 error:
-		icd->error = io_u->error;
+		if (io_u->flags & IO_U_F_DEVICE_ERROR)
+			icd->error = io_u->error;
+		else {
+			/*
+			 * If @io_u has system error(non-device erorr), it must
+			 * have been negative value.
+			 */
+			icd->error = -io_u->error;
+		}
+
 		io_u_log_error(td, io_u);
 	}
 	if (icd->error) {