Unmount nixos-install's leftover chroot bind mounts before zpool export

nixos-install bind-mounts /dev, /proc, /sys (and usually /run) into /mnt to run the target's activation script in a chroot, and doesn't unmount them again afterward. Left in place, those nested mounts made ZFS refuse to unmount its own root dataset at /mnt: zpool export failed with "cannot unmount '/mnt': pool or dataset busy", and because of this script's set -e, that killed the script before it ever reached reboot -- silently defeating the export-before-reboot fix from #40 on every real run, which is why the ZFS-import stall kept recurring.
2026-07-22 04:07:32 +00:00
parent 5d7a6327b7
commit 9bb626327f
1 changed files with 15 additions and 0 deletions
@@ -179,6 +179,21 @@ nixos-install \
    # makes boot stall waiting on the ZFS import. Exporting here (a no-op
    # if the chosen host has no ZFS root, e.g. proxmox-*/linode-*) clears
    # that in-use state so the next import, from any hostid, succeeds.
+    #
+    # nixos-install bind-mounts /dev, /proc, /sys (and usually /run) into
+    # /mnt to run the target's activation script (switch-to-configuration
+    # boot) in a chroot, and doesn't unmount them again once it's done.
+    # Left in place, those nested mounts make ZFS refuse to unmount its own
+    # root dataset at /mnt -- confirmed live: zpool export failed with
+    # "cannot unmount '/mnt': pool or dataset busy", and because of this
+    # script's `set -e`, that killed the script before it ever reached
+    # reboot, silently defeating the whole point of exporting first.
+    for chroot_mount in dev proc sys run; do
+        if mountpoint -q "/mnt/${chroot_mount}"; then
+            umount -R "/mnt/${chroot_mount}"
+        fi
+    done
+
    if [[ -n "$(zpool list -H -o name 2>/dev/null)" ]]; then
        echo "Exporting ZFS pool(s) before reboot..."
        zpool export -a