Dave Chinner - 25.01.18, 06:51:

The video from my talk at LCA 2018 yesterday about the XFS subvolume and
snapshot support I'm working on has been uploaded and can be found
here:

https://www.youtube.com/watch?v=wG8FUvSGROw

I somehow knew that something about snapshots would be coming for XFS after 
seeing the reflink / COW and online scrub/repair work by Darrick. But I am 
highly surprised on the how. I also did not really expect pNFS file layout of 
Christoph to play a role here.

It totally makes sense to me right now, but on the other hand I found myself 
thinking "It can´t be that easy, can it?" after watching your talk.

Easy not in amount of coding work needed and some complexities you mentioned, 
so I totally get that it is a lot of work needed to pull this off, but easy in 
terms of the concept behind it. Yet, if a concept is easy that is quite a hint 
that it might actually be a good one. And if you really can get away with it… 
then by all means, have a go at it!

I am looking forward to this new "extraordinary way to eat your data" 
(Darrick) or create "blammo" and "kaboom" (Dave). :)

From what I understand it is also way less of a "layering violation" than the 

approach in taken in BTRFS or ZFS. Actually it might not be a "layering 
violation" at all, since the different layers are still there and 
communicating with each other. Which opens a lot of potential on applying this 
to other filesystems and storage subsystems of the kernel.

I see benefit in having more than one concept and learn from each other. Maybe 
even a new dog like BTRFS can learn a trick from an old dog at some point in 
time. It sounds crazy to me to think like this at the moment… but for a long 
time it sounded crazy to try to implement snapshots or subvolumes to 
traditional filesystems.

Kudos to thinking out of the box!

-- 
Martin