gce-xfstests: include extra debian packages when building GCE image

index becc23d..8985cef 100644
@@ -313,6 +313,14 @@ create-image".  This will create a new GCE image with a name such as
 "xfstests-201608132226" where 201608132226 indicates when the image
 was created (in this case, August 13, 2016 at 22:26).
 
+As with kvm-xfstests, if you want to include any additional Debian
+packages, or you want to override the default Jessie packages with
+newer versions from jessie-backports, place them in the directory
+kvm-xfstests/test-appliance/debs.  See the [documentation for building
+kvm-xfstests appliances](building-rootfs.md) for more information.
+Note that gce-xfstests requires packages for the amd64 architecture;
+packages for other architectures will not be installed.
+
 This image will be created as part of an image family called xfstests.
 By default, when you start a test using gce-xfstests, the most
 recently created image in the xfstests image family will be used.

index a901476..c0dfabe 100755
@@ -104,6 +104,9 @@ then
 fi
 rm -f $t
 
+# Copy extra debian packages to GS bucket
+gsutil -m rsync -d -r debs/ gs://$GS_BUCKET/debs/
+
 gcloud compute --project "$GCE_PROJECT" -q instances delete "$BLD_INST" \
        --zone "$GCE_ZONE" 2> /dev/null
 gcloud compute --project "$GCE_PROJECT" -q disks delete "$BLD_DISK" 2> /dev/null

index c10645f..563e818 100644
@@ -119,7 +119,8 @@ systemctl enable [email protected]
 systemctl enable [email protected]
 systemctl enable [email protected]
 
-if gsutil -m cp gs://$BUCKET/*.deb /run
+# Install extra debian packages if any
+if gsutil -m cp gs://$BUCKET/debs/*.deb /run
 then
     dpkg -i --ignore-depends=e2fsprogs /run/*.deb
     rm -f /run/*.deb