io_uring: merge defer_prep() and prep_async()

Merge two function and do renaming in favour of the second one, it
relays the meaning better.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs/io_uring.c

@@ -5868,6 +5868,13 @@ static int io_req_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 
 static int io_req_prep_async(struct io_kiocb *req)
 {
+	if (!io_op_defs[req->opcode].needs_async_setup)
+		return 0;
+	if (WARN_ON_ONCE(req->async_data))
+		return -EFAULT;
+	if (io_alloc_async_data(req))
+		return -EAGAIN;
+
 	switch (req->opcode) {
 	case IORING_OP_READV:
 		return io_rw_prep_async(req, READ);
@@ -5880,18 +5887,9 @@ static int io_req_prep_async(struct io_kiocb *req)
 	case IORING_OP_CONNECT:
 		return io_connect_prep_async(req);
 	}
-	return 0;
-}
-
-static int io_req_defer_prep(struct io_kiocb *req)
-{
-	if (!io_op_defs[req->opcode].needs_async_setup)
-		return 0;
-	if (WARN_ON_ONCE(req->async_data))
+	printk_once(KERN_WARNING "io_uring: prep_async() bad opcode %d\n",
+		    req->opcode);
 	return -EFAULT;
-	if (io_alloc_async_data(req))
-		return -EAGAIN;
-	return io_req_prep_async(req);
 }
 
 static u32 io_get_sequence(struct io_kiocb *req)
@@ -5924,7 +5922,7 @@ static int io_req_defer(struct io_kiocb *req)
 	if (!req_need_defer(req, seq) && list_empty_careful(&ctx->defer_list))
 		return 0;
 
-	ret = io_req_defer_prep(req);
+	ret = io_req_prep_async(req);
 	if (ret)
 		return ret;
 	io_prep_async_link(req);
@@ -6339,7 +6337,7 @@ static void io_queue_sqe(struct io_kiocb *req)
 			io_req_complete_failed(req, ret);
 		}
 	} else if (req->flags & REQ_F_FORCE_ASYNC) {
-		ret = io_req_defer_prep(req);
+		ret = io_req_prep_async(req);
 		if (unlikely(ret))
 			goto fail_req;
 		io_queue_async_work(req);
@@ -6492,7 +6490,7 @@ static int io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
 			head->flags |= REQ_F_IO_DRAIN;
 			ctx->drain_next = 1;
 		}
-		ret = io_req_defer_prep(req);
+		ret = io_req_prep_async(req);
 		if (unlikely(ret))
 			goto fail_req;
 		trace_io_uring_link(ctx, req, head);