Support GlusterFS cinder backend

Commit 0971833 added support for multiple cinder backend types.
It initially only contains lvm and nfs. The following patch adds
glusterfs to the backends supported.

Change-Id: I9d5c1dfd4e0d05fcbfe3c35172150c57aa4e6eb2

lib/cinder_backends/glusterfs

@@ -0,0 +1,46 @@
+# lib/cinder_backends/glusterfs
+# Configure the glusterfs backend
+
+# Enable with:
+#
+#   CINDER_ENABLED_BACKENDS+=,glusterfs:<volume-type-name>
+
+# Dependencies:
+#
+# - ``functions`` file
+# - ``cinder`` configurations
+
+# CINDER_CONF
+# CINDER_CONF_DIR
+# CINDER_GLUSTERFS_SHARES - Contents of glusterfs shares config file
+
+# configure_cinder_backend_glusterfs - Configure Cinder for GlusterFS backends
+
+# Save trace setting
+GLUSTERFS_XTRACE=$(set +o | grep xtrace)
+set +o xtrace
+
+
+# Entry Points
+# ------------
+
+# configure_cinder_backend_glusterfs - Set config files, create data dirs, etc
+function configure_cinder_backend_glusterfs {
+    local be_name=$1
+    iniset $CINDER_CONF $be_name volume_backend_name $be_name
+    iniset $CINDER_CONF $be_name volume_driver "cinder.volume.drivers.glusterfs.GlusterfsDriver"
+    iniset $CINDER_CONF $be_name glusterfs_shares_config "$CINDER_CONF_DIR/glusterfs-shares-$be_name.conf"
+
+    if [[ -n "$CINDER_GLUSTERFS_SHARES" ]]; then
+        CINDER_GLUSTERFS_SHARES=$(echo $CINDER_GLUSTERFS_SHARES | tr ";" "\n")
+        echo "$CINDER_GLUSTERFS_SHARES" | tee "$CINDER_CONF_DIR/glusterfs-shares-$be_name.conf"
+    fi
+}
+
+
+# Restore xtrace
+$GLUSTERFS_XTRACE
+
+# Local variables:
+# mode: shell-script
+# End: