copy file With out unlock file c#

Question

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Copylockedfile
{
   public static class FileHelper
    {
        public static bool CopyFile(string fromPath, string toPath, int eachReadLength)
        {
            if (File.Exists(toPath))
            {
                File.Delete(toPath);
            }           
            FileStream fromFile = new FileStream(fromPath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);            
            FileStream toFile = new FileStream(toPath, FileMode.Append, FileAccess.Write, FileShare.ReadWrite);            
            int toCopyLength = 0;           
            if (eachReadLength < fromFile.Length)
            {
                byte[] buffer = new byte[eachReadLength];
                long copied = 0;
                while (copied <= fromFile.Length - eachReadLength)
                {
                    toCopyLength = fromFile.Read(buffer, 0, eachReadLength);
                    fromFile.Flush();
                    toFile.Write(buffer, 0, eachReadLength);
                    toFile.Flush();                
                    toFile.Position = fromFile.Position;
                    copied += toCopyLength;
                }
                int left = (int)(fromFile.Length - copied);
                toCopyLength = fromFile.Read(buffer, 0, left);
                fromFile.Flush();
                toFile.Write(buffer, 0, left);
                toFile.Flush();

            }
            else
            {               
                byte[] buffer = new byte[fromFile.Length];
                fromFile.Read(buffer, 0, buffer.Length);
                fromFile.Flush();
                toFile.Write(buffer, 0, buffer.Length);
                toFile.Flush();

            }
            fromFile.Close();
            toFile.Close();
          
            return true;
        }
    }
}