fatfs问题

菜鸟鸡哥

主要代码如下              

res=f_mkdir("0:loada");
  if(!res)
  {
   res=f_mkdir("0:loada/num");
  }
  res=f_opendir(&dir,"loada/num");
  if(res==FR_OK)
  {
   while(f_readdir(&dir,&fno))
   {
    if(!fno.fname[0])break;//if fil name is free
    
       
   }printf("0:file name:%s\r\n",fno.fname);
  }
  res=f_open(&file,"0:loada/num/infomationaa.txt",FA_OPEN_ALWAYS|FA_READ|FA_WRITE);
  if(res==FR_OK)
  {
 res=f_write(&file,buffer,sizeof(buffer),&bw);//第一次向空的infomationaa.txt里面写入buffer【11】="i love you!"
   if(res==FR_OK)
   {
           res=f_read(&file,buff,sizeof(buff),&br);
       if(res==FR_OK)
       {
        printf("%s\r\n",buff);
       }
     res=f_lseek(&file,(&file)->fsize);//移到文件夹末尾
    {
     if(!res){
      res=f_write(&file,bufferr,sizeof(bufferr),&bw);//第二次向infomationaa.txt里面写入bufferr【11】="fffddddddd!"

      if(res==FR_OK)
      {
       res=f_read(&file,buff,sizeof(buff),&br);
       if(res==FR_OK)
       {
        printf("%s\r\n",buff);
       }
       
       f_printf(&file,"%d",19891025);
       f_printf(&file,"%s","fuck!");
       res=f_read(&file,buff,sizeof(buff),&br);
       if(res==FR_OK)
       {
        printf("%s\r\n",buff);
       }
      }
     }
    }
   }
  }
  f_close(&file);
如红字表示，在串口助手里面调试，发现第二次写入把第一次的数据覆盖了，这是怎么回事？