Reiser4 Is Now Available For The Linux 3.12 Kernel
Uploaded yesterday was the large Reiser4 file-system patch that can be applied against the Linux 3.12.6 stable kernel point release. This is the first Reiser4 patch for the Linux 3.12 kernel and with re-basing it to the new kernel series it was adjusted to use the new shrinker API, has a module alias for the Reiser4 file-system, supports user name-spaces, and has other small changes.
The Reiser4 file-system changes for the Linux 3.12 kernel were done by Mathieu Belanger, Ivan Shapovalov, and Edward Shishkin. The Reiser4 kernel patches for Linux 3.12.6 and other recent kernel releases can be found via its SourceForge hosting.
It still doesn't look like Reiser4 will be mainlined within the Linux kernel anytime soon. There still doesn't appear to be any tier-one distribution or other ISV/IHV willing to back the file-system. Red Hat Enterprise Linux 7 switched to XFS by default over EXT4 in RHEL 6, Ubuntu 14.04 LTS is still sticking to EXT4, and SUSE is shipping EXT4 right now but may switch to Btrfs in their next release and they say Btrfs is already safe for users.
Btrfs hasn't been adopted as quickly as most would have anticipated by now, but there's renewed hope for a more concentrated Btrfs push as the lead Btrfs developers are now working at Facebook. ZFS On Linux is also still advancing but its mainline prospects are also dim due to licensing issues with the Oracle/Sun file-system. F2FS has also been exhibiting much progress and promise. So at the end of the day, do you hold out any hope for Reiser4?
My most recent Reiser4 benchmarks were from a file-system comparison on Linux 3.10 but a new file-system comparison is being published on Phoronix in January.