Extra features
What else do they have to offer?
This is the section where some of our selection have the chance to outperform the recognised favourites. In fact, disabling journaling for ext4 with the $ tune4fs -O ^has_ journal /dev/sdXX is the only extra feature it offers, so ext4 offers nothing more than being a good filesystem.
XFS could be called the same, but it does support multi-threaded writing, while ext4 does only sequential queued writing with one thread, and the difference is clearly visible in the Tiobench results.
Reiser4 has a bounty of extra features, including different transaction models (journaling, copy-on-write and hybrid), transparent compression, plugin infrastructure, delayed space allocation etc. Not everything from that list works stably or works at all, so Reiser4 only gets a few extra points rather than a whole bagful.
There are features aplenty in btrfs, which adds ZFS-like pooling, snapshots and checksums to a general-purpose Linux filesystem. Snapshots mean that you can back up your data right on the filesystem level without using any extra software. With btrfs this is done via mounting subvolumes on top of a root partition with something like $ sudo btrfs subvolume create /dir1/sub1 and listing them with $ btrfs subvolume list and re-mounting a snapshot with a given ID as a top-level FS with subvolid=<ID_number> in /etc/fstab.
ZFS is the most complicated filesystem here and has the highest number of features and, frankly, covering them all goes beyond this Roundup. ZFS is a combined file system and logical volume manager with continuous integrity checking and automatic repair, RAID-Z, deduplication, encryption, snapshot management and almost endless (up to a Zettabyte) expandability. Its power makes it an advanced choice for those who run home servers or build custom-tailored NAS pools.