Todd Gamblin '02 and Christopher Kelley '03

Title: Alternate Implementation of Extended File Attributes on FreeBSD
Abstract: Extended attributes are a mechanism to persistently associate meta-data with files and directories on a filesystem. Although many applications depend on the capability to store dynamic attribute sets, FreeBSD provides no such mechanism in the stable kernel. The TrustedBSD project implemented an extended attribute to support their research into trusted operating systems, which has been merged into the FreeBSD 5.0-CURRENT development branch. The TrustedBSD developers chose to back extended attributes to a per-filesystem, per-attribute backing file to quickly deploy the service with minimal changes to existing installations. We present Ephs, an alternate implementation which uses the interfaces defined by the TrustedBSD project and stores extended attributes into a per-inode disk block in a manner similar to Linux extended attributes. We show that our implementation performs faster than the TrustedBSD implementation under low load and present suggestions for future research.