From LQWiki

JFS (Journaled File System) is a file system developed by IBM. It is based on the JFS file system for IBM's AIX and OS/2 Warp. It was ported to Linux and made open source. It's main aim is for use in server environments by giving high throughput and high reliability. Some of the main features are:

• Journaling (the meta-data)
• B+ tree addressing/directory structure (provides fast file/directory lookup/insert/delete)
• ACL/Extended attributes

JFS has been included in the Linux Kernel since version 2.4.20