From 0f7bdf8946316548500858303549e396655450c5 Mon Sep 17 00:00:00 2001
From: Jes Sorensen <Jes.Sorensen@redhat.com>
Date: Fri, 1 Feb 2013 16:15:18 +0100
Subject: [PATCH] Add support for launching mdmon via systemctl instead of
 fork/exec

If launching mdmon via systemctl fails, we fall back to the old method
of fork/exec. This allows for having mdmon launched via systemctl
which avoids problems with it getting killed by systemd due to it
ending up in the parent's cgroup (udev).

Signed-off-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.de>
---
 Makefile               |  4 ++++
 systemd/mdmon@.service | 18 ++++++++++++++++++
 util.c                 | 28 ++++++++++++++++++++++++++++
 3 files changed, 50 insertions(+)
 create mode 100644 systemd/mdmon@.service

diff --git a/Makefile b/Makefile
index b9787d64..b6edb23d 100644
--- a/Makefile
+++ b/Makefile
@@ -73,6 +73,7 @@ MAP_PATH = $(MAP_DIR)/$(MAP_FILE)
 MDMON_DIR = $(MAP_DIR)
 # place for autoreplace cookies
 FAILED_SLOTS_DIR = /run/mdadm/failed-slots
+SYSTEMD_DIR=/lib/systemd/system
 DIRFLAGS = -DMAP_DIR=\"$(MAP_DIR)\" -DMAP_FILE=\"$(MAP_FILE)\"
 DIRFLAGS += -DMDMON_DIR=\"$(MDMON_DIR)\"
 DIRFLAGS += -DFAILED_SLOTS_DIR=\"$(FAILED_SLOTS_DIR)\"
@@ -264,6 +265,9 @@ install-man: mdadm.8 md.4 mdadm.conf.5 mdmon.8
 install-udev: udev-md-raid.rules
 	$(INSTALL) -D -m 644 udev-md-raid.rules $(DESTDIR)$(UDEVDIR)/rules.d/64-md-raid.rules
 
+install-systemd: systemd/mdmon@.service
+	$(INSTALL) -D -m 644 systemd/mdmon@.service $(DESTDIR)$(SYSTEMD_DIR)/mdmon@.service
+
 uninstall:
 	rm -f $(DESTDIR)$(MAN8DIR)/mdadm.8 $(DESTDIR)$(MAN8DIR)/mdmon.8 $(DESTDIR)$(MAN4DIR)/md.4 $(DESTDIR)$(MAN5DIR)/mdadm.conf.5 $(DESTDIR)$(BINDIR)/mdadm
 
diff --git a/systemd/mdmon@.service b/systemd/mdmon@.service
new file mode 100644
index 00000000..ddb475f2
--- /dev/null
+++ b/systemd/mdmon@.service
@@ -0,0 +1,18 @@
+#  This file is part of mdadm.
+#
+#  mdadm 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.
+
+[Unit]
+Description=MD Metadata Monitor on /dev/%I
+DefaultDependencies=no
+Before=initrd-switch-root.target
+
+[Service]
+ExecStart=/sbin/mdmon %I
+StandardInput=null
+StandardOutput=null
+StandardError=null
+KillMode=none
diff --git a/util.c b/util.c
index e75b7549..01af0b5e 100644
--- a/util.c
+++ b/util.c
@@ -1660,6 +1660,34 @@ int start_mdmon(int devnum)
 	} else
 		pathbuf[0] = '\0';
 
+	/* First try to run systemctl */
+	switch(fork()) {
+	case 0:
+		/* FIXME yuk. CLOSE_EXEC?? */
+		skipped = 0;
+		for (i = 3; skipped < 20; i++)
+			if (close(i) < 0)
+				skipped++;
+			else
+				skipped = 0;
+
+		snprintf(pathbuf, sizeof(pathbuf), "mdmon@%s.service",
+			 devnum2devname(devnum));
+		status = execl("/usr/bin/systemctl", "systemctl", "start",
+			       pathbuf, NULL);
+		status = execl("/bin/systemctl", "systemctl", "start",
+			       pathbuf, NULL);
+		exit(1);
+	case -1: pr_err("cannot run mdmon. "
+			 "Array remains readonly\n");
+		return -1;
+	default: /* parent - good */
+		pid = wait(&status);
+		if (pid >= 0 && status == 0)
+			return 0;
+	}
+
+	/* That failed, try running mdmon directly */
 	switch(fork()) {
 	case 0:
 		/* FIXME yuk. CLOSE_EXEC?? */
-- 
2.39.2