I don't think the performance for btrfs can be considered "close".
And the thing with filesystems is that the format can't really change once stable - and you get locked into an architecture that dictates an awful lot about what features you can provide. So if you want to add zfs-like features to a linux fs that doesn't eat your data/have abysmal performance (btrfs) then you're basically back at square 0 and you have to write a new one.
And the thing with filesystems is that the format can't really change once stable - and you get locked into an architecture that dictates an awful lot about what features you can provide. So if you want to add zfs-like features to a linux fs that doesn't eat your data/have abysmal performance (btrfs) then you're basically back at square 0 and you have to write a new one.