block-device-efi : expand disk size calculation

As noted in the change, 7fd52ba841
increased the size of the EFI partition considerably.  This has meant
that our padding upwards of the disk size is insufficient and EFI
builds (arm64 in particular) is failing due to out-of-disk errors
during final image operations like installing kernels.

Similar to the discussion we had in
I65fa13a088eecdfe61636678578577ea2cfb3c0c, this feels a bit ugly
because we're mixing logic here with sizes specified in block-device
config files.  But it boils down to the same problem; we are
calculating the disk size here and passing it to the block-layer, so
unless we want to make large changes to the status quo about where
these sizes are calculated, small adjustments here are the most KISS
solution.

Thus we check if we have selected the EFI bootloader element, and thus
assume there will be a large system EFI partition and expand the disk
size accordingly.

Change-Id: Ifa05366c2f2b95259f3312e4dde8c85347075ba1

diskimage_builder/lib/disk-image-create

@@ -446,6 +446,18 @@ if [ "$DIB_ROOT_FSTYPE" = "ext4" ] ; then
   fi
 fi
 
+# EFI system partitions default to be quite large at 512mb for maximum
+# compatability (see notes in
+# 7fd52ba84180b4e749ccf4c9db8c49eafff46ea8) .  We need to increase the
+# total size to account for this, or we run out of space creating the
+# final image.  See if we have included the block-device-efi element,
+# which implies we have a large EFI partition, and then pad the final
+# image size.
+if [[ ${IMAGE_ELEMENT} =~ "block-device-efi" ]]; then
+    echo "Expanding disk for EFI partition"
+    du_size=$(( $du_size + (525 * 1024) ))
+fi
+
 # Rounding down size so that is is a multiple of 64, works around a bug in
 # qemu-img that may occur when compressing raw images that aren't a multiple
 # of 64k. https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1180021

releasenotes/notes/efi-bootloader-disk-size-4c1a9f18967104fb.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    When using the ``block-device-efi`` element to create an EFI based
+    system (most notably, with ARM64), the final disk size is now
+    expanded for the 512MiB system EFI partition introduced with 2.24.0