mdmon: use activate spare for re-add

Disks that are not in-sync or failed are not assembled into member
arrays by mdadm.  Teach mdmon to resolve this situation by checking for
spares at start.  imsm_activate_spare() is updated to prefer devices
that can be re-added versus new spares.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 8 insertions, 3 deletions

diff --git a/monitor.c b/monitor.c
index 7cce5a8b..382cad44 100644
--- a/monitor.c
+++ b/monitor.c
@@ -243,10 +243,15 @@ static int read_and_act(struct active_array *a)
 		 * readonly ???
 		 */
 		get_resync_start(a);
-//		printf("Found a readonly array at %llu\n", a->resync_start);
-		if (a->resync_start == ~0ULL)
+		if (a->resync_start == ~0ULL) {
 			a->next_state = read_auto; /* array is clean */
-		else {
+			/* give the metadata a chance to force active if
+			 * we have some recovery to do.  metadata sets
+			 * resync_start to !MaxSector in this case
+			 */
+			a->container->ss->set_array_state(a, 1);
+		}
+		if (a->resync_start != ~0ULL) {
 			a->container->ss->set_array_state(a, 0);
 			a->next_state = active;
 		}