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-rw-r--r--debian/90overlay-root/overlay-mount.sh39
1 files changed, 39 insertions, 0 deletions
diff --git a/debian/90overlay-root/overlay-mount.sh b/debian/90overlay-root/overlay-mount.sh
new file mode 100644
index 0000000..27d0312
--- /dev/null
+++ b/debian/90overlay-root/overlay-mount.sh
@@ -0,0 +1,39 @@
+#!/bin/sh
+
+# make a read-only nfsroot writeable by using overlayfs
+# the nfsroot is already mounted to $NEWROOT
+# add the parameter rootovl to the kernel, to activate this feature
+
+. /lib/dracut-lib.sh
+
+if ! getargbool 0 rootovl ; then
+ return
+fi
+
+modprobe overlay
+
+# a little bit tuning
+mount -o remount,nolock,noatime $NEWROOT
+
+# Move root
+# --move does not always work. Google >mount move "wrong fs"< for
+# details
+mkdir -p /live/image
+mount --bind $NEWROOT /live/image
+umount $NEWROOT
+
+# Create tmpfs
+mkdir /cow
+mount -n -t tmpfs -o mode=0755 tmpfs /cow
+mkdir /cow/work /cow/rw
+
+# Merge both to new Filesystem
+mount -t overlay -o noatime,lowerdir=/live/image,upperdir=/cow/rw,workdir=/cow/work,default_permissions overlay $NEWROOT
+
+# Let filesystems survive pivot
+mkdir -p $NEWROOT/live/cow
+mkdir -p $NEWROOT/live/image
+mount --bind /cow/rw $NEWROOT/live/cow
+umount /cow
+mount --bind /live/image $NEWROOT/live/image
+umount /live/image