2 files changed, 12 insertions, 20 deletions

diff --git a/drivers/md/md.c b/drivers/md/md.c
index fec4abcb9bb4..9ef21d9b8e27 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -2088,7 +2088,6 @@ static void sync_sbs(mddev_t * mddev, int nospares)
                 if (rdev->sb_events == mddev->events ||
                     (nospares &&
                      rdev->raid_disk < 0 &&
-                     (rdev->sb_events&1)==0 &&
                      rdev->sb_events+1 == mddev->events)) {
                         /* Don't update this superblock */
                         rdev->sb_loaded = 2;
@@ -2141,28 +2140,14 @@ repeat:
          * and 'events' is odd, we can roll back to the previous clean state */
         if (nospares
             && (mddev->in_sync && mddev->recovery_cp == MaxSector)
-            && (mddev->events & 1)
-            && mddev->events != 1)
+            && mddev->can_decrease_events
+            && mddev->events != 1) {
                 mddev->events--;
-        else {
+                mddev->can_decrease_events = 0;
+        } else {
                 /* otherwise we have to go forward and ... */
                 mddev->events ++;
-                if (!mddev->in_sync || mddev->recovery_cp != MaxSector) { /* not clean */
-                        /* .. if the array isn't clean, an 'even' event must also go
-                         * to spares. */
-                        if ((mddev->events&1)==0) {
-                                nospares = 0;
-                                sync_req = 2; /* force a second update to get the
-                                               * even/odd in sync */
-                        }
-                } else {
-                        /* otherwise an 'odd' event must go to spares */
-                        if ((mddev->events&1)) {
-                                nospares = 0;
-                                sync_req = 2; /* force a second update to get the
-                                               * even/odd in sync */
-                        }
-                }
+                mddev->can_decrease_events = nospares;
         }
 
         if (!mddev->events) {
@@ -4606,6 +4591,7 @@ static void md_clean(mddev_t *mddev)
         mddev->layout = 0;
         mddev->max_disks = 0;
         mddev->events = 0;
+        mddev->can_decrease_events = 0;
         mddev->delta_disks = 0;
         mddev->new_level = LEVEL_NONE;
         mddev->new_layout = 0;
diff --git a/drivers/md/md.h b/drivers/md/md.h
index a536f5458097..7ab5ea155452 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -150,6 +150,12 @@ struct mddev_s
         int                             external_size; /* size managed
                                                         * externally */
         __u64                           events;
+        /* If the last 'event' was simply a clean->dirty transition, and
+         * we didn't write it to the spares, then it is safe and simple
+         * to just decrement the event count on a dirty->clean transition.
+         * So we record that possibility here.
+         */
+        int                             can_decrease_events;
 
         char                            uuid[16];