From d5027d43ea3969426ba64423b3c0bb38491cc880 Mon Sep 17 00:00:00 2001

From: Tao Liu <ltao@redhat.com>

Date: Fri, 10 Jun 2022 16:39:31 +0800

Subject: [PATCH] feat(lvm): add new module lvmthinpool-monitor

Previously dracut didn't support the feature of lvm thinpool autoextend.

The feature is useful to cases such as kdump, when vmcore to be saved to a

lvm thin volume. The thinpool should be able to autoextend, otherwise an

IO error will be caused and leaves an incomplete vmcore.

There is lvm2-monitor.service and dmeventd avaliable, however

considering [1], it is not suitable for kdump and memory limited cases.

This patch achieves the same by parallel looping a shell function in the

background, which calls lvextend periodically. If thredshold reaches,

autoextend it, if not then nothing happens.

[1]: https://lists.fedoraproject.org/archives/list/kexec@lists.fedoraproject.org/message/YF254ZO3PJ3U56P4OKHV3JNYP2PJUMYX/

Signed-off-by: Tao Liu <ltao@redhat.com>

Resolves: #2098502

---

 dracut.spec                                        |  1 +

 modules.d/80lvmthinpool-monitor/module-setup.sh    | 24 +++++++++++++

 .../start-thinpool-monitor.service                 | 14 ++++++++

 .../start-thinpool-monitor.sh                      | 41 ++++++++++++++++++++++

 4 files changed, 80 insertions(+)

diff --git a/dracut.spec b/dracut.spec

index c8783699..e1c22256 100644

--- a/dracut.spec

+++ b/dracut.spec

@@ -350,6 +350,7 @@ echo 'dracut_rescue_image="yes"' > $RPM_BUILD_ROOT%{dracutlibdir}/dracut.conf.d/

 %{dracutlibdir}/modules.d/50drm

 %{dracutlibdir}/modules.d/50plymouth

 %{dracutlibdir}/modules.d/80lvmmerge

+%{dracutlibdir}/modules.d/80lvmthinpool-monitor

 %{dracutlibdir}/modules.d/90btrfs

 %{dracutlibdir}/modules.d/90crypt

 %{dracutlibdir}/modules.d/90dm

diff --git a/modules.d/80lvmthinpool-monitor/module-setup.sh b/modules.d/80lvmthinpool-monitor/module-setup.sh

new file mode 100755

index 00000000..ca015bdc

--- /dev/null

+++ b/modules.d/80lvmthinpool-monitor/module-setup.sh

@@ -0,0 +1,24 @@

+#!/bin/bash

+

+# called by dracut

+check() {

+    # No point trying to support lvm if the binaries are missing

+    require_binaries lvm sort tr awk || return 1

+

+    return 255

+}

+

+# called by dracut

+depends() {

+    echo lvm

+    return 0

+}

+

+# called by dracut

+install() {

+    inst_multiple sort tr awk

+    inst_script "$moddir/start-thinpool-monitor.sh" "/bin/start-thinpool-monitor"

+

+    inst "$moddir/start-thinpool-monitor.service" "$systemdsystemunitdir/start-thinpool-monitor.service"

+    $SYSTEMCTL -q --root "$initdir" add-wants initrd.target start-thinpool-monitor.service

+}

diff --git a/modules.d/80lvmthinpool-monitor/start-thinpool-monitor.service b/modules.d/80lvmthinpool-monitor/start-thinpool-monitor.service

new file mode 100644

index 00000000..97f5f1f4

--- /dev/null

+++ b/modules.d/80lvmthinpool-monitor/start-thinpool-monitor.service

@@ -0,0 +1,14 @@

+[Unit]

+Description=Lvm thinpool monitor service

+Before=initrd.target

+After=initrd-fs.target

+Conflicts=shutdown.target emergency.target

+

+[Service]

+Type=forking

+ExecStart=/bin/start-thinpool-monitor

+PIDFile=/run/thinpool-moni.pid

+StandardInput=null

+StandardOutput=journal+console

+StandardError=journal+console

+KillSignal=SIGHUP

diff --git a/modules.d/80lvmthinpool-monitor/start-thinpool-monitor.sh b/modules.d/80lvmthinpool-monitor/start-thinpool-monitor.sh

new file mode 100755

index 00000000..75d8eada

--- /dev/null

+++ b/modules.d/80lvmthinpool-monitor/start-thinpool-monitor.sh

@@ -0,0 +1,41 @@

+#!/bin/sh

+

+type getarg > /dev/null 2>&1 || . /lib/dracut-lib.sh

+

+LVS=$(getargs rd.lvm.lv -d rd_LVM_LV=)

+

+is_lvm2_thinp_device() {

+    _device_path=$1

+    _lvm2_thin_device=$(lvm lvs -S 'lv_layout=sparse && lv_layout=thin' \

+        --nosuffix --noheadings -o vg_name,lv_name "$_device_path" 2> /dev/null)

+

+    [ -n "$_lvm2_thin_device" ] && return $?

+}

+

+for LV in $LVS; do

+    if is_lvm2_thinp_device "/dev/$LV"; then

+        THIN_POOLS="$(lvm lvs -S 'lv_layout=sparse && lv_layout=thin' \

+            --nosuffix --noheadings -o vg_name,pool_lv "$LV" \

+            | awk '{printf("%s/%s",$1,$2);}') $THIN_POOLS"

+    fi

+done

+

+THIN_POOLS=$(echo "$THIN_POOLS" | tr ' ' '\n' | sort -u | tr '\n' ' ')

+

+if [ -n "$THIN_POOLS" ]; then

+    if [ -e "/etc/lvm/lvm.conf" ]; then

+        # Use 'monitoring=0' to override the value in lvm.conf, in case

+        # dmeventd monitoring been started after the calling.

+        CONFIG="activation {monitoring=0}"

+    else

+        CONFIG="activation {monitoring=0 thin_pool_autoextend_threshold=70 thin_pool_autoextend_percent=20}"

+    fi

+

+    while true; do

+        for THIN_POOL in $THIN_POOLS; do

+            lvm lvextend --use-policies --config "$CONFIG" "$THIN_POOL"

+        done

+        sleep 5

+    done &

+    echo $! > /run/thinpool-moni.pid

+fi