burrow-pi-img/scripts/qcow2_handling
2019-11-19 15:40:10 +01:00

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# QCOW2 Routines
export CURRENT_IMAGE
export CURRENT_MOUNTPOINT
export NBD_DEV
export MAP_DEV
# set in build.sh
# should be fairly enough for the beginning
# overwrite here by uncommenting following lines
# BASE_QCOW2_SIZE=12G
init_nbd() {
modprobe nbd max_part=16
if [ -z "${NBD_DEV}" ]; then
for x in /sys/class/block/nbd* ; do
S=`cat $x/size`
if [ "$S" == "0" ] ; then
NBD_DEV=/dev/$(basename $x)
MAP_DEV=/dev/mapper/$(basename $x)p1
break
fi
done
fi
}
# mount qcow2 image: mount_image <image file> <mountpoint>
mount_qimage() {
init_nbd
qemu-nbd --discard=unmap -c $NBD_DEV "$1"
kpartx -a $NBD_DEV
mount $MAP_DEV "$2"
CURRENT_IMAGE="$1"
CURRENT_MOUNTPOINT="$2"
}
export -f mount_qimage
# umount qcow2 image: umount_image <current mountpoint>
umount_qimage() {
while mount | grep -q "$1"; do
local LOCS
LOCS=$(mount | grep "$1" | cut -f 3 -d ' ' | sort -r)
for loc in $LOCS; do
echo "$loc"
umount "$loc"
done
done
qemu-nbd -d $NBD_DEV
kpartx -d $NBD_DEV
}
export -f umount_qimage
# create base image / backing image / mount image
load_qimage() {
if [ -z "${CURRENT_MOUNTPOINT}" ]; then
if [ ! -d "${ROOTFS_DIR}" ]; then mkdir -p "${ROOTFS_DIR}"; fi
if [ "${CLEAN}" = "1" ] && [ -f "${WORK_DIR}/image-${STAGE}.qcow2" ]; then rm -f "${WORK_DIR}/image-${STAGE}.qcow2"; fi
if [ ! -f "${WORK_DIR}/image-${STAGE}.qcow2" ]; then
pushd ${WORK_DIR} > /dev/null
init_nbd
if [ -z "${PREV_STAGE}" ]; then
qemu-img create -f qcow2 image-${STAGE}.qcow2 $BASE_QCOW2_SIZE
qemu-nbd --discard=unmap -c $NBD_DEV image-${STAGE}.qcow2
echo 'type=83' | sfdisk $NBD_DEV
kpartx -a $NBD_DEV
mkfs.ext4 $MAP_DEV
else
if [ ! -f "${WORK_DIR}/image-${PREV_STAGE}.qcow2" ]; then exit 1; fi
qemu-img create -f qcow2 \
-o backing_file=${WORK_DIR}/image-${PREV_STAGE}.qcow2 \
${WORK_DIR}/image-${STAGE}.qcow2
qemu-nbd --discard=unmap -c $NBD_DEV image-${STAGE}.qcow2
kpartx -a $NBD_DEV
fi
mount $MAP_DEV "${ROOTFS_DIR}"
CURRENT_IMAGE=${WORK_DIR}/image-${STAGE}.qcow2
CURRENT_MOUNTPOINT=${ROOTFS_DIR}
popd > /dev/null
else
mount_qimage "${WORK_DIR}/image-${STAGE}.qcow2" "${ROOTFS_DIR}"
fi
echo "Current image in use: ${CURRENT_IMAGE} (MP: ${CURRENT_MOUNTPOINT})"
fi
}
export -f load_qimage
# umount current image and refresh mount point env var
unload_qimage() {
if [ ! -z "${CURRENT_MOUNTPOINT}" ]; then
fstrim -v "${CURRENT_MOUNTPOINT}" || true
umount_qimage "${CURRENT_MOUNTPOINT}"
CURRENT_IMAGE=""
CURRENT_MOUNTPOINT=""
fi
}
export -f unload_qimage