kernelnewbies.org
http://kernelnewbies.org/Linux_3.12#head-f0e125622a83f47d0b80e08e807e0252cefc9805
Summary of the changes and new features merged in the Linux kernel during the 3.12 development cycle
his release has also added XFS support for namespaces, and has reincorporated defragmentation support for the new CRC filesystem format.
man 7 namespace の記述
http://man7.org/linux/man-pages/man7/user_namespaces.7.html
Linux 3.11 added support the last of the unsupported major filesystems, XFS.
あと http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=d6970d4b726cea6d7a9bc4120814f95c09571fc3 だとそもそもどのファイルシステム使っていても CONFIG_XFS_FS=n でないならuser namespace使えないんじゃないか、という話になった。実際にカーネルビルドしてみないとなんともいえないけれど。
