given block device sdX, find its dm parent

gistfile1.txt

package main

import (
	"fmt"
	"io/ioutil"
	"os"
	"strings"
)

func main() {
	if len(os.Args) < 2 {
		fmt.Fprintf(os.Stdout, "missing device name(e.g. sda)\n")
		os.Exit(1)
	}

	sys_path := "/sys/block/"
	if dirs, err := ioutil.ReadDir(sys_path); err == nil {
		for _, f := range dirs {
			name := f.Name()
			if strings.HasPrefix(name, "dm-") {
				if _, err1 := os.Lstat(sys_path + name + "/slaves/" + os.Args[1]); err1 == nil {
					fmt.Fprintf(os.Stderr, "found %s, dm is %s\n", os.Args[1], name)
					return
				}
			}
		}
		fmt.Fprintf(os.Stderr, "cannot find %s\n", os.Args[1])
	} else {
		fmt.Fprintf(os.Stderr, "failed to open /sys/block: %v\n", err)
	}
}