Is there some file in Linux that enumerates and describes mount options for file systems like /etc/services describes ports?
If you're asking for "Which filesystems are mounted, and how are they mounted?", the answer can be found by either reading /proc/mounts or running 'mount'.
If you're asking which mount options you have available for the different file systems, you need to check the man page for mount (mount(8)) - it has one section titled "FILESYSTEM SPECIFIC MOUNT OPTIONS", and one titled "FILESYSTEM INDEPENDENT MOUNT OPTIONS" which should give you a pretty good idea of what mount options are available and what they do.
There is no machine-parsable file like
/etc/services, as far as I know.
The most accessible human-readable documentation is the man page for the
Sometimes though the
mount command is not completely up-to-date, there can be options that the kernel supports but not
mount. The options supported by the kernel are documented in its documentation under
Documentation/filesystems/. Options not supported by the
mount command are typically experimental and best left alone in any case; but they sometimes appear in
/proc/mounts when they are the names of options that are enabled by default and best not turned off.