Yes, if the discussion has some fascinating relevance for the general HN readership, I can't figure it out. Linus doesn't come off very well, trying to settle a discussion with common sense and sarcasm while the other people on the thread use facts and examples to paint a more complicated picture.
People who think that userspace filesystems are realistic for anything but toys are just misguided.
I use sshfs all the time. Much of the software I use every day only needs to meet "toy" standards to be useful to me. What is Linus on about here?
Yes, but would you rely on it as the filesystem for a public server?
His point isn't that userspace filesystems are useless, but they are much slower, so the existence of a Fuse filesystem is not an argument for not including a kernel space filesystem in the kernel.
Linus wasn't very clear, but the issue has more to do with the cost of context switches between the kernel and a userland process to support a userland filesystem. These switches are relatively expensive; a good example is the relative throughput of a LUKS/DM-CRYPT encrypted volume compared to a Truecrypt volume with equivalent cipher selections.
LUKS' throughput is much higher, simply because it does not add at least two more kernel<->userspace transitions on every read and write.
Linus insults someone on a forum -> first page on HN !!
Just a thought.