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