Alike to r242314 for GRAID make GMIRROR more aggressive in marking vo…

…lumes

as clean on shutdown and move that action from shutdown_pre_sync stage to
shutdown_post_sync to avoid extra flapping.

ZFS tends to not close devices on shutdown, that doesn't allow GEOM RAID
to shutdown gracefully.  To handle that, mark volume as clean just when
shutdown time comes and there are no active writes.

PR:		kern/113957
MFC after:	2 weeks

sys/geom/mirror/g_mirror.c

@@ -81,7 +81,8 @@ SYSCTL_UINT(_kern_geom_mirror, OID_AUTO, sync_requests, CTLFLAG_RDTUN,
 	G_MIRROR_DEBUG(4, "%s: Woken up %p.", __func__, (ident));	\
 } while (0)
 
-static eventhandler_tag g_mirror_pre_sync = NULL;
+static eventhandler_tag g_mirror_post_sync = NULL;
+static int g_mirror_shutdown = 0;
 
 static int g_mirror_destroy_geom(struct gctl_req *req, struct g_class *mp,
     struct g_geom *gp);
@@ -815,7 +816,7 @@ g_mirror_idle(struct g_mirror_softc *sc, int acw)
 		return (0);
 	if (acw > 0 || (acw == -1 && sc->sc_provider->acw > 0)) {
 		timeout = g_mirror_idletime - (time_uptime - sc->sc_last_write);
-		if (timeout > 0)
+		if (!g_mirror_shutdown && timeout > 0)
 			return (timeout);
 	}
 	sc->sc_idle = 1;
@@ -2821,7 +2822,7 @@ g_mirror_access(struct g_provider *pp, int acr, int acw, int ace)
 			error = ENXIO;
 		goto end;
 	}
-	if (dcw == 0 && !sc->sc_idle)
+	if (dcw == 0)
 		g_mirror_idle(sc, dcw);
 	if ((sc->sc_flags & G_MIRROR_DEVICE_FLAG_DESTROYING) != 0) {
 		if (acr > 0 || acw > 0 || ace > 0) {
@@ -3232,7 +3233,7 @@ g_mirror_dumpconf(struct sbuf *sb, const char *indent, struct g_geom *gp,
 }
 
 static void
-g_mirror_shutdown_pre_sync(void *arg, int howto)
+g_mirror_shutdown_post_sync(void *arg, int howto)
 {
 	struct g_class *mp;
 	struct g_geom *gp, *gp2;
@@ -3242,6 +3243,7 @@ g_mirror_shutdown_pre_sync(void *arg, int howto)
 	mp = arg;
 	DROP_GIANT();
 	g_topology_lock();
+	g_mirror_shutdown = 1;
 	LIST_FOREACH_SAFE(gp, &mp->geom, geom, gp2) {
 		if ((sc = gp->softc) == NULL)
 			continue;
@@ -3250,6 +3252,7 @@ g_mirror_shutdown_pre_sync(void *arg, int howto)
 			continue;
 		g_topology_unlock();
 		sx_xlock(&sc->sc_lock);
+		g_mirror_idle(sc, -1);
 		g_cancel_event(sc);
 		error = g_mirror_destroy(sc, G_MIRROR_DESTROY_DELAYED);
 		if (error != 0)
@@ -3264,18 +3267,18 @@ static void
 g_mirror_init(struct g_class *mp)
 {
 
-	g_mirror_pre_sync = EVENTHANDLER_REGISTER(shutdown_pre_sync,
-	    g_mirror_shutdown_pre_sync, mp, SHUTDOWN_PRI_FIRST);
-	if (g_mirror_pre_sync == NULL)
+	g_mirror_post_sync = EVENTHANDLER_REGISTER(shutdown_post_sync,
+	    g_mirror_shutdown_post_sync, mp, SHUTDOWN_PRI_FIRST);
+	if (g_mirror_post_sync == NULL)
 		G_MIRROR_DEBUG(0, "Warning! Cannot register shutdown event.");
 }
 
 static void
 g_mirror_fini(struct g_class *mp)
 {
 
-	if (g_mirror_pre_sync != NULL)
-		EVENTHANDLER_DEREGISTER(shutdown_pre_sync, g_mirror_pre_sync);
+	if (g_mirror_post_sync != NULL)
+		EVENTHANDLER_DEREGISTER(shutdown_post_sync, g_mirror_post_sync);
 }
 
 DECLARE_GEOM_CLASS(g_mirror_class, g_mirror);