Re: [Libguestfs] [guestfs-tools PATCH] sysprep: remove lvm2's default "system.devices" file

On Sun, Apr 10, 2022 at 01:38:34PM +0200, Laszlo Ersek wrote: > (Background: lvm2 commit 83fe6e720f42, "device usage based on devices > file", 2021-02-23; first released in v2_03_12.) > > "lvm pvscan" may be -- and in RHEL9, will soon be -- restricted to those > block devices whose WWIDs are listed in "/etc/lvm/devices/system.devices". > This is a problem when cloning a VM, as cloning may change the WWIDs of > the domain's disk devices, and then physical volumes underlying the guest > filesystems may not be found. Example: > <https://bugzilla.redhat.com/show_bug.cgi?id=2059545#c12>;. > > Add the "lvm-system-devices" operation for removing this file, so that > "lvm pvscan" investigate all block devices for PVs. > > (Note that this operation is independent from "lvm-uuids". The libguestfs > appliance creates a pristine LVM_SYSTEM_DIR in "appliance/init" (see > libguestfs commit dd162d2cd56a), thus, when "lvm-uuids" calls "g#pvs" and > "g#vgs", those APIs can never be affected by an > "$LVM_SYSTEM_DIR/devices/system.devices" file.) > > Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2072493 > Signed-off-by: Laszlo Ersek <lersek(a)redhat.com&gt; > --- > sysprep/Makefile.am | 1 + > sysprep/sysprep_operation_lvm_system_devices.ml | 44 ++++++++++++++++++++ > 2 files changed, 45 insertions(+) > > diff --git a/sysprep/Makefile.am b/sysprep/Makefile.am > index 0e3afc8a01c7..7d5e8aadf448 100644 > --- a/sysprep/Makefile.am > +++ b/sysprep/Makefile.am > @@ -46,6 +46,7 @@ operations = \ > ipa_client \ > kerberos_data \ > kerberos_hostkeytab \ > + lvm_system_devices \ > lvm_uuids \ > logfiles \ > machine_id \ > diff --git a/sysprep/sysprep_operation_lvm_system_devices.ml b/sysprep/sysprep_operation_lvm_system_devices.ml > new file mode 100644 > index 000000000000..b41fa5dbc23a > --- /dev/null > +++ b/sysprep/sysprep_operation_lvm_system_devices.ml > @@ -0,0 +1,44 @@ > +(* virt-sysprep > + * Copyright (C) 2012-2022 Red Hat Inc. > + * > + * This program is free software; you can redistribute it and/or modify > + * it under the terms of the GNU General Public License as published by > + * the Free Software Foundation; either version 2 of the License, or > + * (at your option) any later version. > + * > + * This program is distributed in the hope that it will be useful, > + * but WITHOUT ANY WARRANTY; without even the implied warranty of > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the > + * GNU General Public License for more details. > + * > + * You should have received a copy of the GNU General Public License along > + * with this program; if not, write to the Free Software Foundation, Inc., > + * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. > + *) > + > +open Sysprep_operation > +open Common_gettext.Gettext > + > +module G = Guestfs > + > +let system_devices_file = "/etc/lvm/devices/system.devices" > + > +let rec lvm_system_devices_perform g root side_effects = > + let typ = g#inspect_get_type root in > + if typ = "linux" then g#rm_f system_devices_file > + > +let op = { > + defaults with > + name = "lvm-system-devices"; > + enabled_by_default = true; > + heading = s_"Remove LVM2 system.devices file"; > + pod_description = > + Some (s_"On Linux guests, LVM2's scanning for physical volumes (PVs) may \ > + be restricted to those block devices whose WWIDs are listed in \ > + C<" ^ system_devices_file ^ ">. When cloning VMs, WWIDs may \ > + change, breaking C<lvm pvscan>. Remove \ > + C<" ^ system_devices_file ^ ">."); > + perform_on_filesystems = Some lvm_system_devices_perform; > +} > + > +let () = register_operation op It wasn't clear from the bug description if we have to remove only /etc/lvm/devices/system.devices or /etc/lvm/devices/*, but assuming it's the first one then this patch looks fine to me.

Reviewed-by: Richard W.M. Jones <rjones(a)redhat.com&gt;