ext4 = started in 2006, stable in 2008, universal on all distros by 2010
btrfs = started in 2007, stable in 2014, mature never?<p>There is no magical point in time where a file system is suddenly &quot;mature&quot;. If anything I&#x27;d argue once OpenSUSE started defaulting to it one should consider it stable. I just wonder why Ubuntu &#x2F; Fedora are not prioritizing making it default since snapshotted upgrades are such a huge usability gain and are trivially easy with btrfs.