From 9419ac28c550d0c06959fcc081b92cf05d5686f1 Mon Sep 17 00:00:00 2001
From: Matthias Klumpp <matthias@tenstral.net>
Date: Sat, 19 Mar 2022 02:34:55 +0100
Subject: [PATCH] Add script to send mail in case btrfs issues were detected

This can be very useful for smaller setups where the admin still would
like to receive an email in case a disk in a btrfs RAID array fails.

Partially resolves #88
---
 btrfs-errmail.service      |  7 +++++
 btrfs-errmail.sh           | 53 ++++++++++++++++++++++++++++++++++++++
 btrfs-errmail.timer        | 10 +++++++
 sysconfig.btrfsmaintenance | 10 +++++++
 4 files changed, 80 insertions(+)
 create mode 100644 btrfs-errmail.service
 create mode 100755 btrfs-errmail.sh
 create mode 100644 btrfs-errmail.timer

diff --git a/btrfs-errmail.service b/btrfs-errmail.service
new file mode 100644
index 0000000..89d4d79
--- /dev/null
+++ b/btrfs-errmail.service
@@ -0,0 +1,7 @@
+[Unit]
+Description=Check for btrfs issues and send an email if any were found
+Documentation=man:btrfs
+
+[Service]
+Type=simple
+ExecStart=/usr/share/btrfsmaintenance/btrfs-errmail.sh
diff --git a/btrfs-errmail.sh b/btrfs-errmail.sh
new file mode 100755
index 0000000..546c086
--- /dev/null
+++ b/btrfs-errmail.sh
@@ -0,0 +1,53 @@
+#!/bin/bash
+#
+# Copyright (c) 2022 Matthias Klumpp <matthias@tenstral.net>
+
+umask 022
+PATH=/sbin:/bin:/usr/sbin:/usr/bin
+export PATH
+
+if [ -f /etc/sysconfig/btrfsmaintenance ] ; then
+    . /etc/sysconfig/btrfsmaintenance
+fi
+
+if [ -f /etc/default/btrfsmaintenance ] ; then
+    . /etc/default/btrfsmaintenance
+fi
+
+. $(dirname $(realpath "$0"))/btrfsmaintenance-functions
+
+if [ -z "$BTRFS_MAILADDR" ]
+then
+      # no email set, nothing to do for us
+      exit 0
+fi
+
+BTRFS_STATS_MOUNTPOINTS=$(expand_auto_mountpoint "auto")
+OIFS="$IFS"
+IFS=:
+for MM in $BTRFS_STATS_MOUNTPOINTS; do
+	if ! is_btrfs "$MM"; then
+		echo "Path $MM is not btrfs, skipping"
+		continue
+	fi
+	devstats=$(btrfs device stats --check $MM 2>&1)
+	if [ $? -ne 0 ]; then
+		mail_body="$(sendmail -t <<EOF
+To: $BTRFS_MAILADDR
+Subject: Btrfs device issue on $MM @ $HOSTNAME
+
+This is an automatically generated mail message from btrfs-errmail
+running on $HOSTNAME
+
+An issue has been detected on the btrfs device mounted as $MM.
+
+Faithfully yours, etc.
+
+P.S. The 'btrfs device stats' output is:
+$devstats
+EOF
+)"
+        fi
+done
+
+exit 0
diff --git a/btrfs-errmail.timer b/btrfs-errmail.timer
new file mode 100644
index 0000000..0df31e4
--- /dev/null
+++ b/btrfs-errmail.timer
@@ -0,0 +1,10 @@
+[Unit]
+Description=Check for btrfs issues and send mail if any were found
+Documentation=man:btrfs
+
+[Timer]
+OnCalendar=hourly
+Persistent=true
+
+[Install]
+WantedBy=timers.target
diff --git a/sysconfig.btrfsmaintenance b/sysconfig.btrfsmaintenance
index cfaa81e..6444685 100644
--- a/sysconfig.btrfsmaintenance
+++ b/sysconfig.btrfsmaintenance
@@ -152,3 +152,13 @@ BTRFS_TRIM_MOUNTPOINTS="/"
 # the timer for these tasks(s) elapsed while the system was suspended
 # or powered off.
 BTRFS_ALLOW_CONCURRENCY="false"
+
+## Path:	System/File systems/btrfs
+## Description:	Mail address to send issue reports to
+## Type: 	string
+## Default:	""
+#
+# If this is set to an email address or an username like "root", btrfs device stats
+# data will be checked every hour and an email will be sent to the given address
+# if any issues(like data corruption or read issues) were found.
+BTRFS_MAILADDR=""