Added easy /usr overlayfs mount for testing purposes

src/etc/fstab

@@ -19,6 +19,9 @@ overlayfs /etc  overlayfs nodev,lowerdir=/mnt/live/etc,upperdir=/mnt/rwroot/etc,
 overlayfs /var  overlayfs nodev,lowerdir=/mnt/live/var,upperdir=/mnt/rwroot/var,workdir=/mnt/rwroot/var-work    0 0
 overlayfs /home overlayfs nodev,lowerdir=/mnt/live/home,upperdir=/mnt/rwroot/home,workdir=/mnt/rwroot/home-work 0 0
 
+# Overlayed subdirectories -- only for testing purposes
+overlayfs /usr  overlayfs noauto,nodev,lowerdir=/mnt/live/usr,upperdir=/mnt/rwroot/usr,workdir=/mnt/rwroot/usr-work 0 0
+
 # Mounted by init.d services (after localmount):
 # procfs:     /proc/sys/fs/binfmt_misc
 

src/root/initrd/init

@@ -40,8 +40,10 @@ mount -t sysfs sysfs /sys
 #   + nodev:              overlayfs mount option
 # (however, nodev still affects bind mounts)
 mount -t tmpfs -o mode=700,nosuid,nodev,noexec,size=${rwrootsz} tmpfs ${srwroot}
-mkdir -m  755 ${srwroot}/etc      ${srwroot}/var      ${srwroot}/home
-mkdir -m  700 ${srwroot}/etc-work ${srwroot}/var-work ${srwroot}/home-work
+for dir in etc var home usr; do
+    mkdir -m 755 ${srwroot}/${dir}
+    mkdir -m 700 ${srwroot}/${dir}-work
+done
 mkdir -m 1777 ${srwroot}/tmp
 
 # /etc and /home can be allowed to exec new/modified executables: