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[dm-devel] [PATCH 13/13] multipathd: no_map_shutdown option



This patchs implements the 'no_map_shutdown' configuration option.
Idea is that the daemon will exit if no maps are found, as then
there's nothing to be done for the daemon anyway.
The daemon will be restarted via socket activation for any CLI
command.
This this option the multipathd.socket unit can be activated always
and won't add to the overall system load.

Signed-off-by: Hannes Reinecke <hare suse de>
---
 libmultipath/config.h         |  1 +
 libmultipath/dict.c           | 32 ++++++++++++++++++++++++++++++++
 multipath.conf.annotated      |  9 +++++++++
 multipath/multipath.conf.5    |  7 +++++++
 multipathd/main.c             | 20 +++++++++++++++-----
 multipathd/multipathd.8       |  4 ++++
 multipathd/multipathd.service |  2 +-
 7 files changed, 69 insertions(+), 6 deletions(-)

diff --git a/libmultipath/config.h b/libmultipath/config.h
index 9c467e8..590fb32 100644
--- a/libmultipath/config.h
+++ b/libmultipath/config.h
@@ -103,6 +103,7 @@ struct config {
 	int fast_io_fail;
 	unsigned int dev_loss;
 	int log_checker_err;
+	int no_map_shutdown;
 	int allow_queueing;
 	uid_t uid;
 	gid_t gid;
diff --git a/libmultipath/dict.c b/libmultipath/dict.c
index 0bf9587..da706f7 100644
--- a/libmultipath/dict.c
+++ b/libmultipath/dict.c
@@ -545,6 +545,25 @@ def_log_checker_err_handler(vector strvec)
 }
 
 static int
+def_no_map_shutdown_handler(vector strvec)
+{
+	char * buff;
+
+	buff = set_value(strvec);
+	if (!buff)
+		return 1;
+
+	if (!strncmp(buff, "on", 2) || !strncmp(buff, "yes", 3) ||
+		 !strncmp(buff, "1", 1))
+		conf->no_map_shutdown = 1;
+	else
+		conf->no_map_shutdown = 0;
+
+	free(buff);
+	return 0;
+}
+
+static int
 def_reservation_key_handler(vector strvec)
 {
 	char *buff;
@@ -2714,6 +2733,18 @@ snprint_def_log_checker_err (char * buff, int len, void * data)
 }
 
 static int
+snprint_def_no_map_shutdown (char * buff, int len, void * data)
+{
+	switch (conf->no_map_shutdown) {
+	case 0:
+		return snprintf(buff, len, "\"no\"");
+	case 1:
+		return snprintf(buff, len, "\"yes\"");
+	}
+	return 0;
+}
+
+static int
 snprint_def_user_friendly_names (char * buff, int len, void * data)
 {
 	if (conf->user_friendly_names  == USER_FRIENDLY_NAMES_ON)
@@ -2850,6 +2881,7 @@ init_keywords(void)
 	install_keyword("reservation_key", &def_reservation_key_handler, &snprint_def_reservation_key);
 	install_keyword("retain_attached_hw_handler", &def_retain_hwhandler_handler, &snprint_def_retain_hwhandler_handler);
 	install_keyword("detect_prio", &def_detect_prio_handler, &snprint_def_detect_prio);
+	install_keyword("no_map_shutdown", &def_no_map_shutdown_handler, &snprint_def_no_map_shutdown);
 	__deprecated install_keyword("default_selector", &def_selector_handler, NULL);
 	__deprecated install_keyword("default_path_grouping_policy", &def_pgpolicy_handler, NULL);
 	__deprecated install_keyword("default_uid_attribute", &def_uid_attribute_handler, NULL);
diff --git a/multipath.conf.annotated b/multipath.conf.annotated
index a20302c..4b56bc8 100644
--- a/multipath.conf.annotated
+++ b/multipath.conf.annotated
@@ -215,6 +215,15 @@
 #	user_friendly_names no
 #
 #	#
+#	# name    : no_map_shutdown
+#	# scope   : multipathd
+#	# desc    : If set to "yes" the multipath daemon will terminate
+#	#           if no multipath devices have been found.
+#	# values  : yes|no
+#	# default : no
+#	no_map_shutdown no
+#
+#	#
 #	# name    : mode
 #	# scope   : multipath & multipathd
 #	# desc    : The mode to use for the multipath device nodes, in octal.
diff --git a/multipath/multipath.conf.5 b/multipath/multipath.conf.5
index cf5bec0..dba0027 100644
--- a/multipath/multipath.conf.5
+++ b/multipath/multipath.conf.5
@@ -409,6 +409,13 @@ will automatically use the
 .I alua
 prioritizer. If not, the prioritizer will be selected as usual. Default is
 .I no
+.TP
+.B no_map_shutdown
+If set to
+.I yes
+, the multipath daemon will terminate if no multipath devices are found.
+Default is
+.I no
 .
 .SH "blacklist section"
 The
diff --git a/multipathd/main.c b/multipathd/main.c
index d386e0a..d4a5809 100644
--- a/multipathd/main.c
+++ b/multipathd/main.c
@@ -1026,11 +1026,11 @@ followover_should_failback(struct path * pp)
 	return 1;
 }
 
-static void
+static int
 defered_failback_tick (vector mpvec)
 {
 	struct multipath * mpp;
-	unsigned int i;
+	unsigned int i, mpp_count = 0;
 
 	vector_foreach_slot (mpvec, mpp, i) {
 		/*
@@ -1042,7 +1042,9 @@ defered_failback_tick (vector mpvec)
 			if (!mpp->failback_tick && need_switch_pathgroup(mpp, 1))
 				switch_pathgroup(mpp);
 		}
+		mpp_count++;
 	}
+	return mpp_count;
 }
 
 static void
@@ -1284,7 +1286,7 @@ checkerloop (void *ap)
 
 	while (1) {
 		struct timeval diff_time, start_time, end_time;
-		int num_paths = 0;
+		int num_paths = 0, num_maps = 0;
 
 		if (gettimeofday(&start_time, NULL) != 0)
 			start_time.tv_sec = 0;
@@ -1300,7 +1302,7 @@ checkerloop (void *ap)
 			}
 		}
 		if (vecs->mpvec) {
-			defered_failback_tick(vecs->mpvec);
+			num_maps = defered_failback_tick(vecs->mpvec);
 			retry_count_tick(vecs->mpvec);
 		}
 		if (count)
@@ -1320,6 +1322,11 @@ checkerloop (void *ap)
 				num_paths, num_paths > 1 ? "s" : "",
 				diff_time.tv_sec, diff_time.tv_usec);
 		}
+		if (!num_maps && conf->no_map_shutdown) {
+			condlog(3, "terminating, no multipath devices");
+			exit_daemon();
+			break;
+		}
 		sleep(1);
 	}
 	return NULL;
@@ -1891,7 +1898,7 @@ main (int argc, char *argv[])
 	if (!conf)
 		exit(1);
 
-	while ((arg = getopt(argc, argv, ":dsv:k::")) != EOF ) {
+	while ((arg = getopt(argc, argv, ":dnsv:k::")) != EOF ) {
 	switch(arg) {
 		case 'd':
 			logsink = 0;
@@ -1904,6 +1911,9 @@ main (int argc, char *argv[])
 
 			conf->verbosity = atoi(optarg);
 			break;
+		case 'n':
+			conf->no_map_shutdown = 1;
+			break;
 		case 's':
 			logsink = -1;
 			break;
diff --git a/multipathd/multipathd.8 b/multipathd/multipathd.8
index 2aea150..eb39c9c 100644
--- a/multipathd/multipathd.8
+++ b/multipathd/multipathd.8
@@ -22,6 +22,10 @@ devmap reconfiguration, so that it can refresh its failed path list.
 .B \-d
 Foreground Mode. Don't daemonize, and print all messages to stdout and stderr.
 .TP
+.B \-n
+Oneshot Mode; daemon will terminate if no multipath devices are found.
+Equivalent to set 'no_map_shutdown' to '1' in the configuration file.
+.TP
 .B \-s
 Suppress timestamps. Do not prefix logging messages with a timestamp.
 .TP
diff --git a/multipathd/multipathd.service b/multipathd/multipathd.service
index 6472dd5..b34667d 100644
--- a/multipathd/multipathd.service
+++ b/multipathd/multipathd.service
@@ -8,7 +8,7 @@ Conflicts=shutdown.target
 [Service]
 Type=notify
 NotifyAccess=main
-ExecStart=/sbin/multipathd -d -s
+ExecStart=/sbin/multipathd -d -s -n
 ExecReload=/sbin/multipathd reconfigure
 WatchdogSec=5s
 LimitCORE=infinity
-- 
1.8.1.4


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