Doubt on FAT file system

    FATFS *fs;/* Pointer to file system object */
    DWORD fre_clust, fre_sect, tot_sect;
    DRESULT Disk;
    FRESULT res1;




    IoInit(); //Timer, UART and LED initialize

    xputs("\nFatFs module test monitor for LPC2388");

    w1 = f_mount(0,fs); // mounting logical drive 0
    xprintf("\r\nmount status %d",w1);

//    res = disk_initialize(0); // physical drive 0. But i dont know why
//      xprintf("\r\n Return value of diak_initilize() is %d",res);

     Disk = disk_status(0); // status if physical drive 0
     xprintf("\r\n Return value of diak_status() is %x",Disk);


    // Get drive information and free clusters
    res1 = f_getfree("/Test.txt", &fre_clust, &fs);
    if (res1)
        put_rc(res1);
    xprintf("\r\n Retuen value of getfree() is %d",res1);

//      xprintf("\r\n Free Clusters %ld",fre_clust);




    // Get total sectors and free sectors
    tot_sect = (fs->max_clust - 2) * fs->csize;
    fre_sect = fre_clust * fs->csize;

    // Print free space in unit of KB (assuming 512B/sector)
    xprintf("%\r\nlu KB total drive space.\n"
           "%lu KB available.\n",
           fre_sect / 2, tot_sect / 2);


    // Open source file
    res1 = f_open(&file1, "Test.txt", FA_OPEN_EXISTING | FA_READ);
    if (res1)
        {
                put_rc(res1);
        }
        xprintf("\r\n status Opening Test1 file %d",res1);

    // Create destination file
    res1 = f_open(&file2, "b.txt", FA_CREATE_ALWAYS | FA_WRITE);
    if (res1)
        {
                put_rc(res1);
        }
        xprintf("\r\n status of opening b file %d",res1);


    // Copy source to destination
    for (;;)
        {
        res1 = f_read(&file1, Buff, sizeof(Buff), &br);
        if (res1 || br == 0)
                {
                        put_rc(res1);
                        xprintf("\r\n Reading status %d",res1);
                        break;   // error or eof
                }
                xprintf("\r\n Read sta %d",w1);
        res1 = f_write(&file2, Buff, br, &bw);
        if (res1 || bw < br)
                {
                        put_rc(res1);
                        xprintf("\r\n write status %d",res1);
                        break;   // error or disk full
                }
        xprintf("\r\n Write Sta %d",w1);
    }

   // Close all files
    f_close(&file1);
    f_close(&file2);

    // Unregister a work area before discard it
    f_mount(0, NULL);