overlay.d/05core: support booting ISO completely from RAM

overlay.d/05core/usr/lib/dracut/modules.d/35coreos-live/coreos-liveiso-persist-osmet.service

@@ -1,12 +1,12 @@
 [Unit]
 Description=Persist Osmet Files (ISO)
-DefaultDependencies=false
 ConditionPathExists=/run/ostree-live
 ConditionKernelCommandLine=coreos.liveiso
 RequiresMountsFor=/run/media/iso
-# on el8, the ISO is mounted by our own systemd unit
-After=run-media-iso-mount.service
 Before=initrd-switch-root.target
+# DefaultDependencies=true so this unit gets stopped on switchroot to
+# allow for /run/media/iso to get unmounted.
+DefaultDependencies=true
 
 [Service]
 Type=oneshot

overlay.d/05core/usr/lib/dracut/modules.d/35coreos-live/live-generator

@@ -54,11 +54,6 @@ ExecStartPost=/usr/sbin/ostree-cmdline stop
 EOF
 
 isoroot=$(getarg coreos.liveiso= ||:)
-is_rhcos8() {
-    # Unfortunately we can't rely on /etc/os-release since el8 doesn't seem to
-    # have https://github.com/dracutdevs/dracut/pull/655.
-    [[ "${isoroot}" == rhcos-* ]] && [[ $(uname -r) == *.el8* ]]
-}
 
 if [ -z "${isoroot}" ]; then
     # In this case, the rootfs is already unpacked into the initrd, or we need
@@ -90,32 +85,8 @@ else
 After=${isosrc_escaped}
 Requires=${isosrc_escaped}
 EOF
-    # Temporary hack for rhel8, where our mount unit can race with udev's
-    # cdrom_id using open(O_EXCL). See:
-    # https://github.com/coreos/fedora-coreos-config/pull/1986#pullrequestreview-1120840529
-    # https://issues.redhat.com/browse/OCPBUGS-1505
-    if is_rhcos8; then
-        cat >"${UNIT_DIR}/run-media-iso-mount.service" <<EOF
-# Automatically generated by live-generator
-
-[Unit]
-DefaultDependencies=false
-# Note that bootup(7) implies that initrd-root-device is After=basic.target
-# but that appears to not be the case.  We explicitly order after sysinit.target
-After=sysinit.target
-After=initrd-root-device.target
-Before=initrd-root-fs.target
 
-[Service]
-Type=oneshot
-RemainAfterExit=yes
-# See https://issues.redhat.com/browse/OCPBUGS-1505
-# and https://github.com/coreos/fedora-coreos-config/pull/411
-ExecStart=/bin/sh -c 'for x in {0..60}; do if mount -o ro -t iso9660 /${isosrc} /run/media/iso; then break; fi; sleep 1; done'
-EOF
-        add_requires run-media-iso-mount.service initrd-root-fs.target
-    else
-        cat >"${UNIT_DIR}/run-media-iso.mount" <<EOF
+    cat >"${UNIT_DIR}/run-media-iso.mount" <<EOF
 # Automatically generated by live-generator
 
 [Unit]
@@ -127,13 +98,42 @@ Wants=systemd-udev-settle.service
 After=sysinit.target
 After=initrd-root-device.target
 Before=initrd-root-fs.target
+# This will make /run/media/iso get unmounted when no longer needed,
+# which will aid in the coreos.liveiso.fromram case.
+StopWhenUnneeded=true
 
 [Mount]
 What=/${isosrc}
 Where=/run/media/iso
 Options=ro
 Type=iso9660
 EOF
+
+    # Determine what to mount in sysroot.mount based on if we were asked to run
+    # completely from RAM via coreos.liveiso.fromram karg.
+    if getargbool 0 coreos.liveiso.fromram; then
+        sysrootrequiresmountsfor=""
+        sysrootfsimg=/rootfs.img
+        # Add service to copy the rootfs.img from the ISO to memory
+        cat >"${UNIT_DIR}/coreos-liveiso-run-media-iso-cp-rootfsimg.service" <<EOF
+# Automatically generated by live-generator
+
+[Unit]
+RequiresMountsFor=/run/media/iso
+Before=sysroot.mount
+# DefaultDependencies=true so this unit gets stopped on switchroot to
+# allow for /run/media/iso to get unmounted.
+DefaultDependencies=true
+
+[Service]
+Type=oneshot
+ExecStart=cp -v /run/media/iso/images/pxeboot/rootfs.img /rootfs.img
+RemainAfterExit=yes
+EOF
+        add_requires coreos-liveiso-run-media-iso-cp-rootfsimg.service default.target
+    else
+        sysrootrequiresmountsfor="RequiresMountsFor=/run/media/iso"
+        sysrootfsimg=/run/media/iso/images/pxeboot/rootfs.img
     fi
 
     cat >"${UNIT_DIR}/sysroot.mount" <<EOF
@@ -142,12 +142,11 @@ EOF
 [Unit]
 DefaultDependencies=false
 Before=initrd-root-fs.target
-RequiresMountsFor=/run/media/iso
-# on el8, the ISO is mounted by our own systemd unit
-After=run-media-iso-mount.service
+After=coreos-liveiso-run-media-iso-cp-rootfsimg.service
+${sysrootrequiresmountsfor}
 
 [Mount]
-What=/run/media/iso/images/pxeboot/rootfs.img
+What=${sysrootfsimg}
 Where=/sysroot
 Type=squashfs
 # Offset of the squashfs within the rootfs cpio.  Assumes newc format