Does this allow you to shrink it or just grow it? If it allows online shrinking then that's bloody fantastic. I doubt it somehow though. I don't know of any other filesystem that can do that off the top of my head.
I'm guessing this is about growing, not shrinking, especially with those stellar results (shrinking normally involves compacting data, so it will take a while).
Nevertheless, very useful, especially on virtualized environments, where you can just "ask" for a bigger disk from a SAN, and online-grow the fs to use it.
How come a 100GB resize is so much faster than a 20GB one?
By the magic of Michael only understanding half of the source before rephrasing everything and passing it off as an article. It's unfortunate, but often reading phoronix news is more productive if you find the external link and read that instead :/
The first resize is from 20GB to 360GB (+340GB), the second from 100GB to 360GB (+260GB). And suddenly the numbers make sense!