I was working with this system today, and noticed that ls wasn't returning all the files in a bucket. After I changed the call from:
gcs_file_system.ls(my_bucket)
To
gcs_file_system.ls(my_bucket, refresh=True)
I can appreciate the value of caching as an option, but returning an outdated file listing doesn't match the semantics of a filesystem ls, leading to user confusion.