It opens the blockfile and doesn't close the fd. Leaving the responsibility to go GC to close the fd

opening_block_file.go

package main

import (
	"fmt"
	"os"
	"runtime"
	"sync"
	"time"
)

var wg *sync.WaitGroup

func test() {
	defer wg.Done()
	f, err := os.OpenFile("/dev/sdb1", os.O_EXCL, 0444)
	if err != nil {
		fmt.Printf("Failed to open /dev/sdb1 file %v\n", err)
		return
	}
	// add finalizer which just prints once it was garbage collected
	runtime.SetFinalizer(f, func(f *os.File) { fmt.Printf("Garbage collected the value %+v\n", f) })
	fmt.Printf("Opend /dev/sdb1 file ===> File %+v, fd: %+v\n", f, f.Fd())
	time.Sleep(10 * time.Second)
}

func main() {
	wg = &sync.WaitGroup{}
	wg.Add(1)
	// Nothing to worry about it launched one go routine and used to waitGroup
	// to synchronize it
	go test()
	wg.Wait()
	// run garbage collection to close the fd
	runtime.GC()
	fmt.Println("Successfully ran the garbage collection")
	// sleep to switch to finalizer goroutine
	time.Sleep(1 * time.Hour)
}