bug: mmap write bug

[sjcsjc123]

When I execute http/http_server_test.go TestPost method under test.go has caused a bug. I found that it comes from the write method under mmap. Please ask personnel related to http and mmap to fix it. This happened after I replaced some of the code, and the replaced code is as follows

func NewIOManager(filename string) (IOManager, error) {
	return NewMMapIOManager(filename)
}