Switch the grenade job to focal

Victoria only supports focal, so the upgrade from victoria
(starting from victoria+1) should use focal.

This patch should not be backported to victoria, because the
upgrades from ussuri still need to use bionic.

In order to make it work on focal:
- do not fail if ebtables does not contain the broute table
  (which happens when it is based on nft);
- when the swift loopback image is remounted on upgrade,
  do not use the nobarrier option, which was removed
  with the 4.19 kernel. See also the corresponding change
  in devstack: I6871a7765e3e04122d8d546f43d36bb8415383fc

Change-Id: If57c54828baf4e250ad08fdd95351490010e1b41

.zuul.yaml

@@ -157,7 +157,7 @@
       Default grenade job
 
       Usually grenade jobs should inherit from this job.
-    nodeset: openstack-single-node-bionic
+    nodeset: openstack-single-node-focal
     required-projects:
       # NOTE(andreaf) The devstack and grenade roles take care of setting up
       # repos on the right branch for this job.
@@ -362,4 +362,4 @@
     description: |
       Basic multinode grenade job
     parent: grenade
-    nodeset: openstack-two-node-bionic
+    nodeset: openstack-two-node-focal

projects/30_swift/upgrade.sh

@@ -69,7 +69,7 @@ sudo chown -R $USER:${USER_GROUP} ${SWIFT_DATA_DIR}
 
 # Mount backing disk
 if ! egrep -q ${SWIFT_DATA_DIR}/drives/sdb1 /proc/mounts; then
-    sudo mount -t xfs -o nouuid,loop,noatime,nodiratime,nobarrier,logbufs=8  \
+    sudo mount -t xfs -o nouuid,loop,noatime,nodiratime,logbufs=8  \
         ${SWIFT_DATA_DIR}/drives/images/swift.img ${SWIFT_DATA_DIR}/drives/sdb1
 fi
 

save-state

@@ -52,7 +52,9 @@ if [[ $(type -P iptables-save) != "" ]]; then
     sudo iptables-save >$SAVE_DIR/iptables.$BASE_RELEASE
 fi
 if [[ $(type -P ebtables) != "" ]]; then
-    sudo ebtables -t broute -L >$SAVE_DIR/ebtables-broute.$BASE_RELEASE
+    # FIXME: ebtables may be available, but based on nft, and broute
+    # is not available -> do not end the script because of this
+    sudo ebtables -t broute -L >$SAVE_DIR/ebtables-broute.$BASE_RELEASE || true
     sudo ebtables -t filter -L >$SAVE_DIR/ebtables-filter.$BASE_RELEASE
     sudo ebtables -t nat -L >$SAVE_DIR/ebtables-nat.$BASE_RELEASE
 fi