Work around a bug in unionfs

Unionfs cannot delete directories that contain open deleted files.
This broke a Nix test.

http://hydra.nixos.org/build/3843354

1 files changed, 8 insertions, 2 deletions

diff --git a/modules/virtualisation/qemu-vm.nix b/modules/virtualisation/qemu-vm.nix
index 9d9581b96c63..eb800e52ab27 100644
--- a/modules/virtualisation/qemu-vm.nix
+++ b/modules/virtualisation/qemu-vm.nix
@@ -293,7 +293,7 @@ in
 
         mkdir /unionfs-chroot/rw-store
         mount -t tmpfs -o "mode=755" none /unionfs-chroot/rw-store
-        unionfs -o allow_other,cow,nonempty,chroot=/unionfs-chroot,max_files=32768 /rw-store=RW:/ro-store=RO $targetRoot/nix/store
+        unionfs -o allow_other,cow,nonempty,chroot=/unionfs-chroot,max_files=32768,hide_meta_files /rw-store=RW:/ro-store=RO $targetRoot/nix/store
       ''}
     '';
 
@@ -313,7 +313,13 @@ in
       )
     '';
 
-  virtualisation.pathsInNixDB = [ config.system.build.toplevel ];
+  virtualisation.pathsInNixDB =
+    [ config.system.build.toplevel
+      # This path from the initrd must be registered as valid because
+      # unionfs uses it from the target Nix store (?).  FIXME: get
+      # unionfs to use the path from the Nix store instead.
+      config.system.build.extraUtils
+    ];
 
   virtualisation.qemu.options = [ "-vga std" "-usbdevice tablet" ];