You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: bolt_unix_solaris.go
    path of file: ./repos/sealer/vendor/go.etcd.io/bbolt
    
    the code of the file until where you have to start completion: package bbolt

import (
	"fmt"
	"syscall"
	"time"
	"unsafe"

	"golang.org/x/sys/unix"
)

// flock acquires an adv
    
func munmap(db *DB) error {
	// Ignore the unmap if we have no mapped data.
	if db.dataref == nil {
		return nil
	}

	// Unmap using the original byte slice.
	err := unix.Munmap(db.dataref)
	db.dataref = nil
	db.data = nil
	db.datasz = 0
	return err
}