In other words, if files are stored with identifying file names, anyone who has access to the physical disk can know which documents are stored on the disk, although not the contents of the documents.
One exception to this is the encryption support being added to the ZFS filesystem.
Filesystem metadata such as filenames, ownership, ACLs, extended attributes are all stored encrypted on disk.
The content of the stored files and directories remain encrypted.
In such cases the cryptographic file system could be 'stacked' on top, to help protect data confidentiality.