Merge pull request #1578 from OSInside/overlay_data_below_tmp

Use custom tmpfs for managing overlays

doc/source/concept_and_workflow/customize_the_boot_process.rst

@@ -189,6 +189,14 @@ the available kernel boot parameters for this modules:
   OS deployment is `/dev/sdj`. With `rd.kiwi.oem.maxdisk=500G` the
   deployment will land on that RAID disk.
 
+``rd.live.overlay.size``
+  Tells a live ISO image the size for the `tmpfs` filesystem that is used
+  for the `overlayfs` mount process. If the write area of the overlayfs
+  mount uses this tmpfs, any new data written during the runtime of
+  the system will fillup this space. The default value used is set
+  to `50%` which means one half of the available RAM space can be used
+  for writing new data.
+
 ``rd.live.overlay.persistent``
   Tells a live ISO image to prepare a persistent
   write partition.

doc/source/image_description/elements.rst

@@ -473,11 +473,31 @@ squashfscompression="uncompressed|gzip|lzo|lz4|xz|zstd":
   Specifies the compression type for mksquashfs
 
 overlayroot="true|false"
-  Specifies to use an overlay root system consisting
-  out of a squashfs compressed read-only root system
-  overlayed using the overlayfs filesystem into an
-  extra read-write partition. Available for the disk
-  image type oem only
+  For the `oem` type only, specifies to use an `overlayfs` based root
+  filesystem consisting out of a squashfs compressed read-only root
+  filesystem combined with a write-partition or tmpfs.
+  The optional kernel boot parameter `rd.root.overlay.readonly` can
+  be used to point the write area into a `tmpfs` instead of
+  the existing persistent write-partition. In this mode all
+  written data is temporary until reboot of the system. The kernel
+  boot parameter `rd.root.overlay.size` can be used to configure
+  the size for the `tmpfs` that is used for the `overlayfs` mount
+  process if `rd.root.overlay.readonly` is requested. That size
+  basically configures the amount of space available for writing
+  new data during the runtime of the system. The default value
+  is set to `50%` which means one half of the available RAM space can
+  be used for writing new data. By default the persistent
+  write-partition is used. The size of that partition can be
+  influenced via the optional `<size>` element in the `<type>`
+  section or via the optional `<oem-resize>` element in the
+  `<oemconfig>` section of the XML description. Setting a fixed
+  `<size>` value will set the size of the image disk to that
+  value and results in an image file of that size. The available
+  space for the write partition is that size reduced by the
+  size the squashfs read-only system needs. If the `<oem-resize>`
+  element is set to `true` an eventually given `<size>` element
+  will not have any effect because the write partition will be
+  resized on first boot to the available disk space.
 
 bootfilesystem="ext2|ext3|ext4|fat32|fat16":
   If an extra boot partition is required this attribute

dracut/modules.d/90kiwi-live/kiwi-generator.sh

@@ -1,6 +1,7 @@
 #!/bin/bash -x
 
 type getarg >/dev/null 2>&1 || . /lib/dracut-lib.sh
+type getOverlayBaseDirectory >/dev/null 2>&1 || . /lib/kiwi-live-lib.sh
 
 [ -z "${root}" ] && root=$(getarg root=)
 
@@ -29,6 +30,7 @@ GENERATOR_DIR="$2"
 [ -z "$GENERATOR_DIR" ] && exit 1
 [ -d "$GENERATOR_DIR" ] || mkdir "$GENERATOR_DIR"
 
+OVERLAY_BASE="$(getOverlayBaseDirectory)"
 ROOTFLAGS="$(getarg rootflags)"
 {
     echo "[Unit]"
@@ -37,7 +39,7 @@ ROOTFLAGS="$(getarg rootflags)"
     echo "[Mount]"
     echo "Where=/sysroot"
     echo "What=LiveOS_rootfs"
-    echo "Options=${ROOTFLAGS},lowerdir=/run/rootfsbase,upperdir=/run/overlayfs/rw,workdir=/run/overlayfs/work"
+    echo "Options=${ROOTFLAGS},lowerdir=${OVERLAY_BASE}/rootfsbase,upperdir=${OVERLAY_BASE}/overlayfs/rw,workdir=${OVERLAY_BASE}/overlayfs/work"
     echo "Type=overlay"
     _dev=LiveOS_rootfs
 } > "$GENERATOR_DIR"/sysroot.mount

dracut/modules.d/90kiwi-live/kiwi-live-lib.sh

@@ -1,6 +1,20 @@
 #!/bin/bash
 type getarg >/dev/null 2>&1 || . /lib/dracut-lib.sh
 
+function getOverlayBaseDirectory {
+    # initialize and print overlay base directory below which
+    # the iso and overlayfs based mountpoints are managed
+    local overlay_base=/run/overlay
+    local overlay_size
+    mkdir -p "${overlay_base}"
+    if ! mountpoint -q "${overlay_base}";then
+        overlay_size=$(getarg rd.live.overlay.size)
+        [ -z "${overlay_size}" ] && overlay_size="50%"
+        mount -t tmpfs -o "size=${overlay_size}" tmpfs "${overlay_base}"
+    fi
+    echo "${overlay_base}"
+}
+
 function lookupIsoDiskDevice {
     local root=$1
     local iso_label=${root#/dev/disk/by-label/}
@@ -100,8 +114,10 @@ function initGlobalOptions {
 }
 
 function mountIso {
-    ln -s "${isodev}" /run/initramfs/isodev
-    local iso_mount_point=/run/initramfs/live
+    local overlay_base
+    overlay_base=$(getOverlayBaseDirectory)
+    ln -s "${isodev}" "${overlay_base}/isodev"
+    local iso_mount_point="${overlay_base}/live"
     mkdir -m 0755 -p "${iso_mount_point}"
     if ! mount -o ro -n -t "${isofs_type}" "${isodev}" "${iso_mount_point}"; then
         die "Failed to mount live ISO device"
@@ -111,7 +127,9 @@ function mountIso {
 
 function mountCompressedContainerFromIso {
     local iso_mount_point=$1
-    local container_mount_point=/run/initramfs/squashfs_container
+    local overlay_base
+    overlay_base=$(getOverlayBaseDirectory)
+    local container_mount_point="${overlay_base}/squashfs_container"
     squashfs_container="${iso_mount_point}/${live_dir}/${squash_image}"
     mkdir -m 0755 -p "${container_mount_point}"
     if ! mount -n "${squashfs_container}" "${container_mount_point}";then
@@ -122,8 +140,10 @@ function mountCompressedContainerFromIso {
 
 function mountReadOnlyRootImageFromContainer {
     local container_mount_point=$1
+    local overlay_base
+    overlay_base=$(getOverlayBaseDirectory)
     local rootfs_image="${container_mount_point}/LiveOS/rootfs.img"
-    local root_mount_point=/run/rootfsbase
+    local root_mount_point="${overlay_base}/rootfsbase"
     mkdir -m 0755 -p "${root_mount_point}"
     if ! mount -n "${rootfs_image}" "${root_mount_point}"; then
         die "Failed to mount live ISO root filesystem"
@@ -132,15 +152,19 @@ function mountReadOnlyRootImageFromContainer {
 }
 
 function prepareTemporaryOverlay {
-    mkdir -m 0755 -p /run/overlayfs/rw
-    mkdir -m 0755 -p /run/overlayfs/work
+    local overlay_base
+    overlay_base=$(getOverlayBaseDirectory)
+    mkdir -m 0755 -p "${overlay_base}/overlayfs/rw"
+    mkdir -m 0755 -p "${overlay_base}/overlayfs/work"
 }
 
 function preparePersistentOverlay {
     if [ -z "${isodiskmode}" ] || [ -z "${isodiskdev}" ]; then
         return 1
     fi
-    local overlay_mount_point=/run/overlayfs
+    local overlay_base
+    overlay_base=$(getOverlayBaseDirectory)
+    local overlay_mount_point="${overlay_base}/overlayfs"
     mkdir -m 0755 -p "${overlay_mount_point}"
     if [ "${isodiskmode}" = "disk_boot" ];then
         if ! preparePersistentOverlayDiskBoot "${overlay_mount_point}"; then
@@ -151,8 +175,8 @@ function preparePersistentOverlay {
             return 1
         fi
     fi
-    mkdir -m 0755 -p ${overlay_mount_point}/rw
-    mkdir -m 0755 -p ${overlay_mount_point}/work
+    mkdir -m 0755 -p "${overlay_mount_point}/rw"
+    mkdir -m 0755 -p "${overlay_mount_point}/work"
 }
 
 function preparePersistentOverlayLoopBoot {

dracut/modules.d/90kiwi-live/module-setup.sh

@@ -29,7 +29,7 @@ install() {
     inst_multiple \
         umount dmsetup blockdev blkid lsblk dd losetup \
         grep cut partprobe find wc fdisk tail mkfs.ext4 mkfs.xfs \
-        dialog cat
+        dialog cat mountpoint
 
     dmsquashdir=$(find "${dracutbasedir}/modules.d" -name "*dmsquash-live")
     if [ -n "${dmsquashdir}" ] && \

dracut/modules.d/90kiwi-live/parse-kiwi-live.sh

@@ -2,6 +2,7 @@
 # live images are specified with
 # root=live:CDLABEL=label
 # root=live:AOEINTERFACE=name
+type getOverlayBaseDirectory >/dev/null 2>&1 || . /lib/kiwi-live-lib.sh
 
 [ -z "${root}" ] && root=$(getarg root=)
 
@@ -33,8 +34,10 @@ info "root was ${liveroot}, is now ${root}"
 # make sure that init doesn't complain
 [ -z "${root}" ] && root="live"
 
-wait_for_dev -n /run/rootfsbase
-wait_for_dev -n /run/overlayfs/rw
-wait_for_dev -n /run/overlayfs/work
+OVERLAY_BASE="$(getOverlayBaseDirectory)"
+
+wait_for_dev -n "${OVERLAY_BASE}/rootfsbase"
+wait_for_dev -n "${OVERLAY_BASE}/overlayfs/rw"
+wait_for_dev -n "${OVERLAY_BASE}/overlayfs/work"
 
 return 0

dracut/modules.d/90kiwi-overlay/kiwi-generator.sh

@@ -1,6 +1,7 @@
 #!/bin/bash
 
 type getarg >/dev/null 2>&1 || . /lib/dracut-lib.sh
+type getOverlayBaseDirectory >/dev/null 2>&1 || . /lib/kiwi-filesystem-lib.sh
 
 [ -z "${root}" ] && root=$(getarg root=)
 
@@ -24,6 +25,7 @@ GENERATOR_DIR="$2"
 [ -z "$GENERATOR_DIR" ] && exit 1
 [ -d "$GENERATOR_DIR" ] || mkdir "$GENERATOR_DIR"
 
+OVERLAY_BASE="$(getOverlayBaseDirectory)"
 ROOTFLAGS="$(getarg rootflags)"
 {
     echo "[Unit]"
@@ -32,7 +34,7 @@ ROOTFLAGS="$(getarg rootflags)"
     echo "[Mount]"
     echo "Where=/sysroot"
     echo "What=OverlayOS_rootfs"
-    echo "Options=${ROOTFLAGS},lowerdir=/run/rootfsbase,upperdir=/run/overlayfs/rw,workdir=/run/overlayfs/work"
+    echo "Options=${ROOTFLAGS},lowerdir=${OVERLAY_BASE}/rootfsbase,upperdir=${OVERLAY_BASE}/overlayfs/rw,workdir=${OVERLAY_BASE}/overlayfs/work"
     echo "Type=overlay"
     _dev=OverlayOS_rootfs
 } > "$GENERATOR_DIR"/sysroot.mount

dracut/modules.d/90kiwi-overlay/kiwi-overlay-root.sh

@@ -1,6 +1,7 @@
 #!/bin/bash
 # root=overlay:UUID=uuid was converted to
 # root=block:/dev/disk/by-uuid/uuid in cmdline hook
+type getOverlayBaseDirectory >/dev/null 2>&1 || . /lib/kiwi-filesystem-lib.sh
 
 #======================================
 # functions
@@ -35,22 +36,33 @@ function initGlobalDevices {
 }
 
 function mountReadOnlyRootImage {
-    local root_mount_point=/run/rootfsbase
-    mkdir -m 0755 -p ${root_mount_point}
+    local overlay_base
+    overlay_base=$(getOverlayBaseDirectory)
+    local root_mount_point="${overlay_base}/rootfsbase"
+    mkdir -m 0755 -p "${root_mount_point}"
     if ! mount -n "${read_only_partition}" "${root_mount_point}"; then
         die "Failed to mount overlay(ro) root filesystem"
     fi
     echo "${root_mount_point}"
 }
 
+function prepareTemporaryOverlay {
+    local overlay_base
+    overlay_base=$(getOverlayBaseDirectory)
+    mkdir -m 0755 -p "${overlay_base}/overlayfs/rw"
+    mkdir -m 0755 -p "${overlay_base}/overlayfs/work"
+}
+
 function preparePersistentOverlay {
-    local overlay_mount_point=/run/overlayfs
-    mkdir -m 0755 -p ${overlay_mount_point}
+    local overlay_base
+    overlay_base=$(getOverlayBaseDirectory)
+    local overlay_mount_point="${overlay_base}/overlayfs"
+    mkdir -m 0755 -p "${overlay_mount_point}"
     if ! mount "${write_partition}" "${overlay_mount_point}"; then
         die "Failed to mount overlay(rw) filesystem"
     fi
-    mkdir -m 0755 -p ${overlay_mount_point}/rw
-    mkdir -m 0755 -p ${overlay_mount_point}/work
+    mkdir -m 0755 -p "${overlay_mount_point}/rw"
+    mkdir -m 0755 -p "${overlay_mount_point}/work"
 }
 
 #======================================
@@ -73,7 +85,11 @@ loadKernelModules
 mountReadOnlyRootImage
 
 # prepare overlay for generated systemd OverlayOS_rootfs service
-preparePersistentOverlay
+if getargbool 0 rd.root.overlay.readonly; then
+    prepareTemporaryOverlay
+else
+    preparePersistentOverlay
+fi
 
 need_shutdown
 

dracut/modules.d/90kiwi-overlay/module-setup.sh

@@ -7,7 +7,7 @@ check() {
 
 # called by dracut
 depends() {
-    echo rootfs-block dm
+    echo rootfs-block dm kiwi-lib
     return 0
 }
 

dracut/modules.d/99kiwi-lib/kiwi-filesystem-lib.sh

@@ -1,5 +1,19 @@
 type getarg >/dev/null 2>&1 || . /lib/dracut-lib.sh
 
+function getOverlayBaseDirectory {
+    # initialize and print overlay base directory below which
+    # the overlayfs based mountpoints are managed
+    local overlay_base=/run/overlay
+    local overlay_size
+    mkdir -p "${overlay_base}"
+    if ! mountpoint -q "${overlay_base}";then
+        overlay_size=$(getarg rd.root.overlay.size)
+        [ -z "${overlay_size}" ] && overlay_size="50%"
+        mount -t tmpfs -o "size=${overlay_size}" tmpfs "${overlay_base}"
+    fi
+    echo "${overlay_base}"
+}
+
 function resize_filesystem {
     local device=$1
     test -n "${device}" || return

dracut/modules.d/99kiwi-lib/module-setup.sh

@@ -16,7 +16,7 @@ install() {
     declare moddir=${moddir}
     inst_multiple \
         blkid blockdev dd mkdir rmdir \
-        grep cut tail head tr bc true false \
+        grep cut tail head tr bc true false mountpoint \
         basename partprobe sfdisk sgdisk mkswap readlink lsblk \
         btrfs xfs_growfs resize2fs \
         e2fsck btrfsck xfs_repair \

package/python-kiwi-spec-template

@@ -345,6 +345,7 @@ Summary:        KIWI - Dracut module for vmx(+overlay) image type
 # to set up the build environment...
 BuildRequires:  dracut
 %endif
+Requires:       dracut-kiwi-lib = %{version}-%{release}
 Requires:       util-linux
 Requires:       dracut
 License:        GPL-3.0-or-later