io_uring: cleanup io_alloc_async_ctx()

to #28170604

commit 3d9932a8b240c9019f48358e8a6928c53c2c7f6b upstream

Cleanup io_alloc_async_ctx() a bit, add a new __io_alloc_async_ctx(),
so io_setup_async_rw() won't need to check whether async_ctx is true
or false again.
Reviewed-by: NStefano Garzarella <sgarzare@redhat.com>
Signed-off-by: NXiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
Acked-by: NJoseph Qi <joseph.qi@linux.alibaba.com>

fs/io_uring.c

@@ -2472,12 +2472,18 @@ static void io_req_map_rw(struct io_kiocb *req, ssize_t io_size,
 	}
 }
 
+static inline int __io_alloc_async_ctx(struct io_kiocb *req)
+{
+	req->io = kmalloc(sizeof(*req->io), GFP_KERNEL);
+	return req->io == NULL;
+}
+
 static int io_alloc_async_ctx(struct io_kiocb *req)
 {
 	if (!io_op_defs[req->opcode].async_ctx)
 		return 0;
-	req->io = kmalloc(sizeof(*req->io), GFP_KERNEL);
-	return req->io == NULL;
+
+	return  __io_alloc_async_ctx(req);
 }
 
 static int io_setup_async_rw(struct io_kiocb *req, ssize_t io_size,
@@ -2487,7 +2493,7 @@ static int io_setup_async_rw(struct io_kiocb *req, ssize_t io_size,
 	if (!io_op_defs[req->opcode].async_ctx)
 		return 0;
 	if (!req->io) {
-		if (io_alloc_async_ctx(req))
+		if (__io_alloc_async_ctx(req))
 			return -ENOMEM;
 
 		io_req_map_rw(req, io_size, iovec, fast_iov, iter);