Use SD_ACTIVATION env. var. in systemd units to better detect systemd in use.

LISTEN_PID and LISTEN_FDS environment variables are defined only during systemd
"start" action. But we still need to know whether we're activated during
"reload" action as well - we use the reload action to call "dmeventd -R"/"lvmetad -R"
for statefull daemon restart. We can't use normal "restart" as that is simply
composed of "stop" and "start" and we would lose any state the daemon has.

5 files changed, 15 insertions, 0 deletions

diff --git a/WHATS_NEW_DM b/WHATS_NEW_DM
index afa69445..ef3f2105 100644
--- a/WHATS_NEW_DM
+++ b/WHATS_NEW_DM
@@ -1,5 +1,6 @@
 Version 1.02.75 - 
 ================================
+  Use SD_ACTIVATION env. var. in systemd units to better detect systemd in use.
   Do not run a new dmeventd instance on restart if there's no existing one.
   Make the time window for reading fifo longer 5sec (1.02.73).
 
diff --git a/daemons/dmeventd/dmeventd.c b/daemons/dmeventd/dmeventd.c
index b61fb8b8..0b3da1e4 100644
--- a/daemons/dmeventd/dmeventd.c
+++ b/daemons/dmeventd/dmeventd.c
@@ -56,6 +56,7 @@
 #  define OOM_SCORE_ADJ_MIN (-1000)
 
 /* Systemd on-demand activation support */
+#  define SD_ACTIVATION_ENV_VAR_NAME "SD_ACTIVATION"
 #  define SD_LISTEN_PID_ENV_VAR_NAME "LISTEN_PID"
 #  define SD_LISTEN_FDS_ENV_VAR_NAME "LISTEN_FDS"
 #  define SD_LISTEN_FDS_START 3
@@ -1698,6 +1699,10 @@ static int _systemd_handover(struct dm_event_fifos *fifos)
 
 	memset(fifos, 0, sizeof(*fifos));
 
+	/* SD_ACTIVATION must be set! */
+	if (!(e = getenv(SD_ACTIVATION_ENV_VAR_NAME)) || strcmp(e, "1"))
+		goto out;
+
 	/* LISTEN_PID must be equal to our PID! */
 	if (!(e = getenv(SD_LISTEN_PID_ENV_VAR_NAME)))
 		goto out;
@@ -1729,6 +1734,7 @@ static int _systemd_handover(struct dm_event_fifos *fifos)
 	}
 
 out:
+	unsetenv(SD_ACTIVATION_ENV_VAR_NAME);
 	unsetenv(SD_LISTEN_PID_ENV_VAR_NAME);
 	unsetenv(SD_LISTEN_FDS_ENV_VAR_NAME);
 	return r;
diff --git a/libdaemon/server/daemon-server.c b/libdaemon/server/daemon-server.c
index 3cdec348..3e72cd11 100644
--- a/libdaemon/server/daemon-server.c
+++ b/libdaemon/server/daemon-server.c
@@ -69,6 +69,7 @@ static void _exit_handler(int sig __attribute__((unused)))
 #  define OOM_SCORE_ADJ_MIN (-1000)
 
 /* Systemd on-demand activation support */
+#  define SD_ACTIVATION_ENV_VAR_NAME "SD_ACTIVATION"
 #  define SD_LISTEN_PID_ENV_VAR_NAME "LISTEN_PID"
 #  define SD_LISTEN_FDS_ENV_VAR_NAME "LISTEN_FDS"
 #  define SD_LISTEN_FDS_START 3
@@ -164,6 +165,10 @@ static int _systemd_handover(struct daemon_state *ds)
 	unsigned long env_pid, env_listen_fds;
 	int r = 0;
 
+	/* SD_ACTIVATION must be set! */
+	if (!(e = getenv(SD_ACTIVATION_ENV_VAR_NAME)) || strcmp(e, "1"))
+		goto out;
+
 	/* LISTEN_PID must be equal to our PID! */
 	if (!(e = getenv(SD_LISTEN_PID_ENV_VAR_NAME)))
 		goto out;
@@ -188,6 +193,7 @@ static int _systemd_handover(struct daemon_state *ds)
 		ds->socket_fd = SD_FD_SOCKET_SERVER;
 
 out:
+	unsetenv(SD_ACTIVATION_ENV_VAR_NAME);
 	unsetenv(SD_LISTEN_PID_ENV_VAR_NAME);
 	unsetenv(SD_LISTEN_FDS_ENV_VAR_NAME);
 	return r;
diff --git a/scripts/dm_event_systemd_red_hat.service.in b/scripts/dm_event_systemd_red_hat.service.in
index dc83c6d8..02a24c6f 100644
--- a/scripts/dm_event_systemd_red_hat.service.in
+++ b/scripts/dm_event_systemd_red_hat.service.in
@@ -9,6 +9,7 @@ DefaultDependencies=no
 Type=forking
 ExecStart=@sbindir@/dmeventd
 ExecReload=@sbindir@/dmeventd -R
+Environment=SD_ACTIVATION=1
 PIDFile=@DMEVENTD_PIDFILE@
 OOMScoreAdjust=-1000
 
diff --git a/scripts/lvm2_lvmetad_systemd_red_hat.service.in b/scripts/lvm2_lvmetad_systemd_red_hat.service.in
index afb46c22..44827fde 100644
--- a/scripts/lvm2_lvmetad_systemd_red_hat.service.in
+++ b/scripts/lvm2_lvmetad_systemd_red_hat.service.in
@@ -11,6 +11,7 @@ NonBlocking=true
 ExecStart=@sbindir@/lvmetad
 ExecStartPost=@sbindir@/vgscan
 ExecReload=@sbindir@/lvmetad -R
+Environment=SD_ACTIVATION=1
 Restart=on-abort
 PIDFile=@DEFAULT_RUN_DIR@/lvmetad.pid