如何使用Mongodb在Golang中使用批量更新获取更新的文档ID

I am working on a golang project. I am using MongoDB database. I need to get the all documents ids with the bulk update function. I am using mgo golang package with the code below:

package main

import (
   "fmt"
   "gopkg.in/mgo.v2/bson"
   "gopkg.in/mgo.v2"
)
type QueryStruct struct{
   Selector    bson.M
   Query       bson.M   
}

func main(){
   session, err := mgo.Dial("127.0.0.1")
   if err != nil {
      panic(err)
   }

   defer session.Close()

   session.SetMode(mgo.Monotonic, true)
   var queries []QueryStruct
   for i:=1; i<=400; i++{
      var query QueryStruct
      query.Selector = bson.M{"country":"US"}
      query.Query = bson.M{"$set":bson.M{"serial_number":i}}
      queries = append(queries, query)
   }
   c := session.DB("test").C("people")
   bulk := c.Bulk()
   for _, queryVal := range queries{
       bulk.UpdateAll(queryVal.Selector, queryVal.Query)
   }
   data, err := bulk.Run()
   fmt.Println(data)
   fmt.Println(err)
}

I am getting the output like this:

&{117 117 false}
<nil>

I need to get the updated document ids to maintain the logs if any entry is not updated.

Can anybody suggest me how I can achieve this?