commit e1b942b9afa9f3310ea19c57caea896af97b557e
Author: Tomasz Majchrzak <tomasz.majchrzak@intel.com>
Date:   Thu Sep 7 13:01:16 2017 +0200

    Grow: stop previous reshape process first
    
    If array is stopped during reshape and assembled again straight away,
    reshape process in a background might still be running. systemd doesn't
    start a new service if one already exists. If there is a race, previous
    process might terminate and new one is not created. Reshape doesn't
    continue after assemble.
    
    Tell systemd to restart the service rather than just start it. It will
    assure previous service is stopped first. If it's not running, stopping
    has no effect and only new process is started.
    
    Signed-off-by: Tomasz Majchrzak <tomasz.majchrzak@intel.com>
    Signed-off-by: Jes Sorensen <jsorensen@fb.com>

diff --git a/Grow.c b/Grow.c
index 534ba80..267b06f 100644
--- a/Grow.c
+++ b/Grow.c
@@ -3003,9 +3003,9 @@ static int continue_via_systemd(char *devnm)
 		snprintf(pathbuf, sizeof(pathbuf), "mdadm-grow-continue@%s.service",
 			 devnm);
 		status = execl("/usr/bin/systemctl", "systemctl",
-			       "start",
+			       "restart",
 			       pathbuf, NULL);
-		status = execl("/bin/systemctl", "systemctl", "start",
+		status = execl("/bin/systemctl", "systemctl", "restart",
 			       pathbuf, NULL);
 		exit(1);
 	case -1: /* Just do it ourselves. */