[$] A filesystem for namespaces

It is natural, when looking at the kernel development process, to focus onpatches that find their way to acceptance and become a part of futurekernels. But there can be value in looking at work that doesn't clear thebar; in failing, these patches often reveal things about the kernel and thecommunity that creates it. Such is the case with the proof-of-conceptnamespacefspatch series recently posted by Yordan Karadzhov. One should notexpect to see namespacefs in a future kernel but, in failing, this workshowed a real use case and why it is hard to satisfy that use case in thekernel.