golang json无法正确解析带有嵌入式结构标签的字段[关闭]

package main

import (
    "encoding/json"
    "fmt"
)

type InnerData struct {
    M int64 `josn:"m"`
    N int64 `json:"n"`
}

//JSONData is a json data example
type JSONData struct {
    Hello string    `json:"hello"`
    Data  InnerData `json:"data"`
}

func main() {
    v := JSONData{Hello: "world", Data: InnerData{N: 100000, M: 123456}}
    mashaled, err := json.Marshal(&v)
    if err != nil {
        fmt.Println(err)
        return
    }
    fmt.Println(string(mashaled))
}

Noted the field M in InnerData has a tag m, so the expected result is :{"hello":"world","data":{"m":123456,"n":100000}}. While I have

{"hello":"world","data":{"M":123456,"n":100000}}

Does anyone know how to fix the problem, or where am I wrong?