[pve-devel] [PATCH v2 manager] postinst: set custom LVM settings

[Fabian Grünbichler]

now that we no longer ship our own LVM packages, set the relevant
filtering options here if they are missing.

for an upgrade from PVE 6.x, the following two scenarios are likely:

A: user edited config provided by our old lvm2 package. it likely
contains our (or a modified) global_filter, but the old scan_lvs
default. in this case we ignore global_filter as long as it contains our
'don't scan zvols' entry, and set scan_lvs to false.

B: config provided by our old lvm2 package was taken over by default
config from stock lvm2 package. scan_lvs defaults to false already, but
global_filter is unset (scan everything), so we need to set our own
global_filter excluding zvols.

other combinations should be handled fine as well.

for new installs (installer, install on top of Debian Bullseye) we are
always in scenario B.

Signed-off-by: Fabian Grünbichler <f.gruenbichler at proxmox.com>
---

Notes:
    once other difference between our old config and the stock one is that we had
    'issue_discards' enabled. we could either put this in the release notes, or
    also enable it here automatically - but it is less straight-forward since the
    default is not "almost certainly wrong" like for the filtering options..
    
    we could drop the "check for marker" and just do this once on initial install
    and upgrades from 6.x, but since the fallout from not having these in place can
    be data corruption (activating multiple VGs with same name, using one from a
    guest on the host!) I'd rather play it safe..
    
    v2:
    - move more variables into if branch
    - export env variable to suppress LVM warnings (thanks Thomas)
    - fix grep for marker ("any lines that don't match" vs "no lines that match")

 debian/postinst | 56 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 56 insertions(+)

diff --git a/debian/postinst b/debian/postinst
index 85f2a70a..0f6296c3 100755
--- a/debian/postinst
+++ b/debian/postinst
@@ -8,6 +8,60 @@ set -e
 # done its automatic conffile handling, and all the packages we depend
 # of are already fully installed and configured.
 
+set_lvm_conf() {
+    LVM_CONF_MARKER="# added by pve-manager to avoid scanning"
+
+    # only do these changes once
+    # keep user changes afterwards provided marker is still there..
+    if ! grep -qLF "$LVM_CONF_MARKER" /etc/lvm/lvm.conf; then
+	OLD_VALUE="$(lvmconfig --typeconfig full devices/global_filter)"
+	NEW_VALUE='global_filter=["r|/dev/zd.*|"]'
+
+	export LVM_SUPPRESS_FD_WARNINGS=1
+
+	# check global_filter
+	# keep previous setting from our custom packaging if it is still there
+	if echo "$OLD_VALUE" | grep -qvF 'r|/dev/zd.*|'; then
+	    SET_FILTER=1
+	    BACKUP=1
+	fi
+	# should be the default since bullseye
+	if lvmconfig --typeconfig full devices/scan_lvs | grep -qv 'scan_lvs=0'; then
+	    SET_SCAN_LVS=1
+	    BACKUP=1
+	fi
+	if test -n "$BACKUP"; then
+	    echo "Backing up lvm.conf before setting pve-manager specific settings.."
+	    cp -vb /etc/lvm/lvm.conf /etc/lvm/lvm.conf.bak
+	fi
+	if test -n "$SET_FILTER"; then
+	    echo "Setting 'global_filter' in /etc/lvm/lvm.conf to prevent zvols from being scanned:"
+	    echo "$OLD_VALUE => $NEW_VALUE"
+	    # comment out existing setting
+	    sed -i -e 's/^\([[:space:]]*global_filter[[:space:]]*=\)/#\1/' /etc/lvm/lvm.conf
+	    # add new section with our setting
+	    cat >> /etc/lvm/lvm.conf <<EOF
+devices {
+	 $LVM_CONF_MARKER ZFS zvols
+	 $NEW_VALUE
+}
+EOF
+	fi
+	if test -n "$SET_SCAN_LVS"; then
+	    echo "Adding scan_lvs=0 setting to /etc/lvm/lvm.conf to prevent LVs from being scanned."
+	    # comment out existing setting
+	    sed -i -e 's/^\([[:space:]]*scan_lvs[[:space:]]*=\)/#\1/' /etc/lvm/lvm.conf
+	    # add new section with our setting
+	    cat >> /etc/lvm/lvm.conf <<EOF
+devices {
+	 $LVM_CONF_MARKER LVM volumes
+	 scan_lvs=0
+}
+EOF
+	fi
+    fi
+}
+
 case "$1" in
   triggered)
     # We don't print a status message here, as dpkg already said
@@ -109,6 +163,8 @@ case "$1" in
 	fi
     fi
 
+    set_lvm_conf
+
     if test ! -e /proxmox_install_mode; then
 	# modeled after code generated by dh_start
 	for unit in ${UNITS}; do
-- 
2.30.2