[pve-devel] [PATCH installer v2] zfs: create dataset var-lib-vz for /var/lib/vz

[Stoiko Ivanov <s.ivanov@proxmox.com>]

Creating rpool/var/lib/vz and all intermediate datasets causes a
service-failure of `var.mount` upon shutdown.

creating the dataset for /var/lib/vz directly at the rpool and setting
its mountpoint property seems the most robust way to address this.

The alternative approach of setting `canmount=off` on the `var`
dataset seems a bit dangerous (users setting a zfs property and
suddenly hiding their /var contents).

The only small downside to this approach is that the setting of the
mountpoint happens quite a bit after extracting the data - but this
would probably be better addressed with a refactoring of the
lowlevel-installer code (setting the zfs-pool up under /target and
getting rid of a few special cases)

Fixes: dd19d40ceac179ba18652f1d6c3e4c23f246af00
Suggested-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
Signed-off-by: Stoiko Ivanov <s.ivanov@proxmox.com>
---
huge Thanks to Fabian - for the feedback and patiently walking me through
the potential pitfalls!

 Proxmox/Install.pm | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/Proxmox/Install.pm b/Proxmox/Install.pm
index 811db8c..1ed38c1 100644
--- a/Proxmox/Install.pm
+++ b/Proxmox/Install.pm
@@ -187,8 +187,8 @@ sub zfs_create_rpool {
 
     if ($iso_env->{product} eq 'pve') {
 	syscmd("zfs create $pool_name/data")  == 0 || die "unable to create zfs $pool_name/data volume\n";
-	syscmd("zfs create -p $pool_name/ROOT/$root_volume_name/var/lib/vz")  == 0 ||
-	    die "unable to create zfs $pool_name/ROOT/$root_volume_name/var/lib/vz volume\n";
+	syscmd("zfs create -o mountpoint=/$pool_name/ROOT/$root_volume_name/var/lib/vz $pool_name/var-lib-vz")  == 0 ||
+	    die "unable to create zfs $pool_name/var-lib-vz volume\n";
     }
 
     # default to `relatime` on, fast enough for the installer and production
@@ -1335,6 +1335,11 @@ _EOD
 	syscmd("zfs set mountpoint=/ $zfs_pool_name/ROOT/$zfs_root_volume_name") == 0 ||
 	    die "zfs set mountpoint failed\n";
 
+	if ($iso_env->{product} eq 'pve') {
+	    syscmd("zfs set mountpoint=/var/lib/vz $zfs_pool_name/var-lib-vz") == 0 ||
+		die "zfs set mountpoint for var-lib-vz failed\n";
+	}
+
 	syscmd("zpool set bootfs=$zfs_pool_name/ROOT/$zfs_root_volume_name $zfs_pool_name") == 0 ||
 	    die "zpool set bootfs failed\n";
 	syscmd("zpool export $zfs_pool_name");
-- 
2.39.2