What attribuites are included in filesystem metadata for docker COPY instruction?

From the documentation:

COPY obeys the following rules:

The <src> path must be inside the context of the build; you cannot COPY ../something /something, because the first step of a docker build is to send the context directory (and subdirectories) to the docker daemon.

If <src> is a directory, the entire contents of the directory are copied, including filesystem metadata.

Does anyone know what attributes are included in the filesystem metadata?

note: this is causing intermediate layer cache invalidation for me and I want to figure out what exactly is the root cause of it. Thanks.