26a8f21ab2
as described in the zfs bug https://github.com/openzfs/zfs/issues/10931 the kernel keeps around cached data from mmaps after a rollback, thus having invalid data in files that were allegedly rolled back to workaround this (until a real fix comes along), we unmount the subvol, invalidating the kernel cache anyway the dataset gets mounted on the next 'activate_volume' again Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>