libvirt has built in support for glusterfs (with libgfapi provided by sys-cluster/glusterfs instead of FUSE mount), which is enabled by --with-storage-gluster. A quick patch against the current ebuild is attatched. btw: same for sheepdog, but that's apperantly not packaged yet
Created attachment 391758 [details, diff] ebuild patch for glusterfs support
I've named the new use flag "glusterfs". Introduced in 1.2.11-r1 and 9999. Further, a minimal dependency on glusterfs-3.4.2* is necessary. *libvirt-1.2.11-r1 (18 Dec 2014) 18 Dec 2014; Matthias Maier <tamiko@gentoo.org> +libvirt-1.2.11-r1.ebuild, -libvirt-1.2.11.ebuild, libvirt-9999.ebuild, metadata.xml: add support for glusterfs, bug #532632