JFS (Journaled File System) is a 64-bit journaling filesystem created by IBM. An implementation for the Linux kernel is available as free software under the terms of the GNU General Public License. It is low on resource usage and comparatively fast doing all kinds of filesystem operations (as opposed to being specialized in some, e.g. XFS is fast with big files, but slower with small ones). As such JFS is especially good for usage with battery-powered devices such as laptops.
JFS is supported in the standard Linux kernel:
File systems ---> <*> JFS filesystem support
Optional JFS features:
File systems ---> <*> JFS filesystem support [*] JFS POSIX Access Control Lists [*] JFS Security Labels [ ] JFS debugging [*] JFS statistics
Filesystem utilities are available in the sys-fs/jfsutils package:
emerge --ask sys-fs/jfsutils