clickfs on Linux

[Eddie Kohler]

Hi,

Repatch your 2.2.{18,19,20} kernel, then run ./configure with the
--enable-clickfs option to play with Click's new purpose-built filesystem.

Controlling Click through /proc had a few bad effects. Among them:

* Wasted memory and time for creating and removing all the /proc/click
  entries for a new configuration (not usually a big deal, but it made
  hotswaps slower).
* A limited number of inode numbers available under /proc meant you could
  run out of /proc/click files (a bigger deal).
* /proc's limited extensibility (no one cares).

So Click now comes with its own filesystem. It behaves pretty much
exactly as the /proc/click filesystem did, only it appears under /click,
and doesn't suffer from /proc's limitations. The idea for this came from
Nickolai Zeldovich's clickfs on FreeBSD; thanks!

With clickfs, "insmod click.o" isn't good enough to install Click any more.
Use "click-install". In particular, the Click kernel module now depends on
another kernel module, 'proclikefs.o', so you can unload the Click module
without unmounting its filesystem. "click-install" installs proclikefs.o,
installs click.o, and mounts the Click filesystem on "/click", if
necessary.

Compile without "--enable-clickfs" to keep the old /proc way of doing
things. However, "--enable-clickfs" will become the default soon.

Clickfs does not yet work under Linux 2.4.

Eddie