Why Reiser4 Is Not in the Kernel
The question of if and when Reiser4 will be merged into the mainline Linux kernel has been an on-going debate for a couple of years. The filesystem was described as being "fairly stable for average users" by Hans Reiser [interview] over two years ago, in March of 2004 . It has been merged into Andrew Morton [interview]'s -mm kernel , though issues such as Reiser4 plugins and coding style caused lengthy discussions last year. Two recent threads on the lkml raised the question again, asking at a non-technical level why Reiser 4 has not been included in the Linux kernel.
Hans Reiser posted a "short term task list for Reiser4" to address the remaining technical issues.