Full SysFS path of a device

def _syspath(dev):
    '''
    Full SysFS path of a device
    '''
    dev = _devbase(dev)
    dev = re.sub(r'^([vhs][a-z]+)([0-9]+)', r'\1/\1\2', dev)

    # name = re.sub(r'^([a-z]+)(?<!(bcache|md|dm))([0-9]+)', r'\1/\1\2', name)
    return os.path.join('/sys/block/', dev)