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Fix overlay mount: use separate mount points for squashfs and overlay

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The overlay mount was failing because it tried to mount overlay onto /root
while also using /root as the lowerdir source. This is invalid - you cannot
overlay-mount a directory onto itself.

Fix: Mount squashfs to /mnt/squashfs, tmpfs to /mnt/overlay, then mount
overlay onto /root using the squashfs mount as lowerdir.
This commit is contained in:
Torbjørn Lindahl
2026-02-01 15:59:58 +01:00
parent b7a52c0c37
commit eaaacc2f68
1 changed files with 31 additions and 22 deletions
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53
initramfs/scripts/netboot
View File

@@ -3,7 +3,8 @@
export PATH=/usr/bin:/usr/sbin:/bin:/sbin
MOUNTPOINT=/root
TMPFS_MOUNT=/mnt
SQUASHFS_MOUNT=/mnt/squashfs
OVERLAY_TMPFS=/mnt/overlay
# Hook functions for initramfs-tools boot script integration
netboot_top()
@@ -125,51 +126,59 @@ mountroot() {
if echo "${FILE_NAME}" | grep -q squashfs; then
log_begin_msg "Setting up SquashFS with overlay"
# Mount read-only SquashFS
if ! mount -t squashfs "${FILE_PATH}" "${MOUNTPOINT}" -o ro; then
log_failure_msg "Failed to mount SquashFS at ${MOUNTPOINT}"
rm -f "${FILE_PATH}"
return ${rc}
fi
log_begin_msg "SquashFS mounted at ${MOUNTPOINT}"
log_end_msg
# Setup overlay if requested
# Setup overlay if requested - need separate mount points
if [ -n "${OVERLAYROOT}" ]; then
log_begin_msg "Mounting ${OVERLAYROOT} for overlay"
# Create mount points
mkdir -p "${SQUASHFS_MOUNT}" "${OVERLAY_TMPFS}"
# Mount read-only SquashFS to separate location
if ! mount -t squashfs "${FILE_PATH}" "${SQUASHFS_MOUNT}" -o ro; then
log_failure_msg "Failed to mount SquashFS at ${SQUASHFS_MOUNT}"
rm -f "${FILE_PATH}"
return ${rc}
fi
log_begin_msg "SquashFS mounted at ${SQUASHFS_MOUNT}"
log_end_msg
log_begin_msg "Mounting tmpfs for overlay upper/work"
# Create tmpfs for upper and work directories
if ! mount -o size=2G -t "${OVERLAYROOT}" tmpfs_overlay "${TMPFS_MOUNT}"; then
if ! mount -t tmpfs -o size=2G tmpfs_overlay "${OVERLAY_TMPFS}"; then
log_failure_msg "Failed to mount tmpfs for overlay"
umount "${MOUNTPOINT}"
umount "${SQUASHFS_MOUNT}"
rm -f "${FILE_PATH}"
return ${rc}
fi
# Create overlay structure
mkdir -p "${TMPFS_MOUNT}/upper" "${TMPFS_MOUNT}/work"
mkdir -p "${OVERLAY_TMPFS}/upper" "${OVERLAY_TMPFS}/work"
# Mount overlay combining read-only lower + writable upper
# Mount overlay combining read-only lower + writable upper onto /root
if ! mount -t overlay \
-o "lowerdir=${MOUNTPOINT},upperdir=${TMPFS_MOUNT}/upper,workdir=${TMPFS_MOUNT}/work" \
-o "lowerdir=${SQUASHFS_MOUNT},upperdir=${OVERLAY_TMPFS}/upper,workdir=${OVERLAY_TMPFS}/work" \
overlay_root "${MOUNTPOINT}"; then
log_failure_msg "Failed to mount overlay filesystem"
umount "${TMPFS_MOUNT}"
umount "${MOUNTPOINT}"
umount "${OVERLAY_TMPFS}"
umount "${SQUASHFS_MOUNT}"
rm -f "${FILE_PATH}"
return ${rc}
fi
log_end_msg
log_begin_msg "Overlay mounted successfully"
log_begin_msg "Overlay mounted at ${MOUNTPOINT} (lower=${SQUASHFS_MOUNT})"
log_end_msg
# Clean up downloaded image as it's now mounted
rm -f "${FILE_PATH}"
rc=0
else
# Direct SquashFS mount without overlay
log_begin_msg "Mounted SquashFS without overlay"
# Direct SquashFS mount without overlay - mount directly to /root
if ! mount -t squashfs "${FILE_PATH}" "${MOUNTPOINT}" -o ro; then
log_failure_msg "Failed to mount SquashFS at ${MOUNTPOINT}"
rm -f "${FILE_PATH}"
return ${rc}
fi
log_begin_msg "Mounted SquashFS without overlay at ${MOUNTPOINT}"
log_end_msg
rc=0
fi