fix(dmsquash-live-root): check kernel for built-in `overlay` drivers

Do not assume that `overlay` is always a module.  Check first for
`overlay` in `/proc/filesystems`. This is needed in the --no-kernel
use case to avoid the error: modprobe:
  FATAL: Module overlay not found in directory /lib/modules/<kver>

Signed-off-by: Federico Vaga <federico.vaga@cern.ch>

diff --git a/modules.d/90dmsquash-live/dmsquash-live-root.sh b/modules.d/90dmsquash-live/dmsquash-live-root.sh
index abc68407f40c2b36a27a27b14b46f605ce0588e6..cb3fe5d06afa417461126a79dbb1df280929f695 100755 (executable)
--- a/modules.d/90dmsquash-live/dmsquash-live-root.sh
+++ b/modules.d/90dmsquash-live/dmsquash-live-root.sh
@@ -177,7 +177,7 @@ do_live_overlay() {
         fi
     fi
     if [ -n "$overlayfs" ]; then
-        if ! modprobe overlay; then
+        if ! { strstr "$(< /proc/filesystems)" overlay || modprobe overlay; }; then
             if [ "$overlayfs" = required ]; then
                 die "OverlayFS is required but not available."
                 exit 1