[$] Improving pseudo filesystems

The eventfs filesystem provides an interface to the tracepoints that are available
to be used by various Linux tracing tools (e.g. ftrace, perf, uprobes,
etc.); it is meant to be a version of the tracefs filesystem that
dynamically allocates its entries as needed. The goal is to reduce the memory
required for multiple instances of tracefs, as Steven Rostedt described in
a session at the 2022
Linux Storage,
Filesystem, Memory Management, and BPF Summit. He returned to the 2024
edition of the summit to talk further about how to make pseudo (or virtual)
filesystems, such as tracefs/eventfs, more like regular Linux filesystems,
where the directory entries (dentries) and inodes are only created (and
cached) as needed.