[PATCH v3 04/13] io_uring/cmd: introduce io_uring_cmd_complete

[Pavel Begunkov <asml.silence@gmail.com>]

io_uring_cmd_complete() does exactly what io_uring_cmd_done() does, that
is completing the request, but doesn't ask for issue_flags argument. We
have a couple of users hardcoding some random issue_flags values in
drivers, which they absolutely should not do. This function will be used
to get rid of them. Also, add comments warning users that they're only
allowed to pass issue_flags that were given from io_uring.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 include/linux/io_uring/cmd.h | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/include/linux/io_uring/cmd.h b/include/linux/io_uring/cmd.h
index e453a997c060..bf94ed4135d8 100644
--- a/include/linux/io_uring/cmd.h
+++ b/include/linux/io_uring/cmd.h
@@ -26,12 +26,25 @@ static inline const void *io_uring_sqe_cmd(const struct io_uring_sqe *sqe)
 #if defined(CONFIG_IO_URING)
 int io_uring_cmd_import_fixed(u64 ubuf, unsigned long len, int rw,
 			      struct iov_iter *iter, void *ioucmd);
+
+/*
+ * Completes the request, i.e. posts an io_uring CQE and deallocates @ioucmd
+ * and the corresponding io_uring request.
+ *
+ * Note: the caller should never hard code @issue_flags and is only allowed
+ * to pass the mask provided by the core io_uring code.
+ */
 void io_uring_cmd_done(struct io_uring_cmd *cmd, ssize_t ret, ssize_t res2,
 			unsigned issue_flags);
+
 void __io_uring_cmd_do_in_task(struct io_uring_cmd *ioucmd,
 			    void (*task_work_cb)(struct io_uring_cmd *, unsigned),
 			    unsigned flags);
 
+/*
+ * Note: the caller should never hard code @issue_flags and only use the
+ * mask provided by the core io_uring code.
+ */
 void io_uring_cmd_mark_cancelable(struct io_uring_cmd *cmd,
 		unsigned int issue_flags);
 
@@ -56,6 +69,21 @@ static inline void io_uring_cmd_mark_cancelable(struct io_uring_cmd *cmd,
 }
 #endif
 
+/*
+ * Completes the request, i.e. posts an io_uring CQE and deallocates @ioucmd
+ * and the corresponding io_uring request. Similar to io_uring_cmd_done() but
+ * doesn't need issue_flags.
+ *
+ * Note, must not be used with cancellable requests.
+ */
+static inline void io_uring_cmd_complete(struct io_uring_cmd *ioucmd,
+					 ssize_t ret, ssize_t res2)
+{
+	if (WARN_ON_ONCE(ioucmd->flags & IORING_URING_CMD_CANCELABLE))
+		return;
+	io_uring_cmd_done(ioucmd, ret, res2, IO_URING_F_UNLOCKED);
+}
+
 /* users must follow the IOU_F_TWQ_LAZY_WAKE semantics */
 static inline void io_uring_cmd_do_in_task_lazy(struct io_uring_cmd *ioucmd,
 			void (*task_work_cb)(struct io_uring_cmd *, unsigned))
-- 
2.44.0