Exit when there are no more arrays to manage.

managemon.c

@@ -382,6 +382,8 @@ void wake_me(int sig)
 	woke = 1;
 }
 
+int exit_now = 0;
+int manager_ready = 0;
 void do_manager(struct supertype *container)
 {
 	struct mdstat_ent *mdstat;
@@ -395,6 +397,9 @@ void do_manager(struct supertype *container)
 	do {
 		woke = 0;
 
+		if (exit_now)
+			exit(0);
+
 		mdstat = mdstat_read(1, 0);
 
 		manage(mdstat, container);
@@ -405,6 +410,7 @@ void do_manager(struct supertype *container)
 
 		remove_old();
 
+		manager_ready = 1;
 		sigprocmask(SIG_SETMASK, &block, &orig);
 		if (woke == 0)
 			mdstat_wait_fd(container->sock, &orig);

mdadm.h

@@ -460,6 +460,7 @@ struct supertype {
 			*  external:/md0/12
 			*/
 	int devcnt;
+	char *device_name; /* e.g. /dev/md/whatever */
 
 	struct mdinfo *devs;
 

mdmon.c

@@ -146,6 +146,14 @@ static void try_kill_monitor(char *devname)
 		kill(pid, SIGTERM);
 }
 
+void remove_pidfile(char *devname)
+{
+	char buf[100];
+
+	sprintf(buf, "/var/run/mdadm/%s.pid", devname);
+	unlink(buf);
+}
+
 static int make_control_sock(char *devname)
 {
 	char path[100];
@@ -198,6 +206,7 @@ int main(int argc, char *argv[])
 	container = malloc(sizeof(*container));
 	container->devnum = fd2devnum(mdfd);
 	container->devname = devnum2devname(container->devnum);
+	container->device_name = argv[1];
 
 	/* If this fails, we hope it already exists */
 	mkdir("/var/run/mdadm", 0600);
@@ -267,7 +276,7 @@ int main(int argc, char *argv[])
 			argv[1]);
 		exit(3);
 	}
-
+	close(mdfd);
 	close(mdfd);
 
 	mlockall(MCL_FUTURE);

mdmon.h

@@ -33,6 +33,7 @@ extern struct active_array *pending_discard;
 extern struct md_generic_cmd *active_cmd;
 
 
+void remove_pidfile(char *devname);
 void do_monitor(struct supertype *container);
 void do_manager(struct supertype *container);
 
@@ -41,3 +42,5 @@ int read_dev_state(int fd);
 struct mdstat_ent *mdstat_read(int hold, int start);
 
 extern struct superswitch super_ddf, super_ddf_bvd, super_ddf_svd;
+
+extern int exit_now, manager_ready;

monitor.c

@@ -436,11 +436,12 @@ static int handle_pipe(struct md_generic_cmd *cmd, struct active_array *aa)
 	return -1;
 }
 
-static int wait_and_act(struct active_array **aap, int pfd,
+static int wait_and_act(struct supertype *container, int pfd,
 			int monfd, int nowait)
 {
 	fd_set rfds;
 	int maxfd = 0;
+	struct active_array **aap = &container->arrays;
 	struct active_array *a, **ap;
 	int rv;
 	struct mdinfo *mdi;
@@ -473,6 +474,22 @@ static int wait_and_act(struct active_array **aap, int pfd,
 		ap = &(*ap)->next;
 	}
 
+	if (manager_ready && *aap == NULL) {
+		/* No interesting arrays. Lets see about exiting.
+		 * Note that blocking at this point is not a problem
+		 * as there are no active arrays, there is nothing that
+		 * we need to be ready to do.
+		 */
+		int fd = open(container->device_name, O_RDONLY|O_EXCL);
+		if (fd >= 0 || errno != EBUSY) {
+			/* OK, we are safe to leave */
+			exit_now = 1;
+			signal_manager();
+			remove_pidfile(container->devname);
+			exit(0);
+		}
+	}
+
 	if (!nowait) {
 		rv = select(maxfd+1, &rfds, NULL, NULL, NULL);
 
@@ -521,7 +538,7 @@ void do_monitor(struct supertype *container)
 	int rv;
 	int first = 1;
 	do {
-		rv = wait_and_act(&container->arrays, container->mgr_pipe[0],
+		rv = wait_and_act(container, container->mgr_pipe[0],
 				  container->mon_pipe[1], first);
 		first = 0;
 	} while (rv >= 0);