Update recovery_offset even when external metadata is used.

The update of ->recovery_offset in sync_sbs is appropriate even then external
metadata is in use.  However sync_sbs is only called when native
metadata is used.

So move that update in to the top of md_update_sb (which is the only
caller of sync_sbs) before the test on ->external.

This moves the update out of ->write_lock protection, but those fields
only need ->reconfig_mutex protection which they still have.

Also move the test on ->persistent up to where ->external is set as
for metadata update purposes they are the same.

Clear MD_CHANGE_DEVS and MD_CHANGE_CLEAN as they can only be confusing
if ->external is set or ->persistent isn't.

Finally move the update of ->utime down as it is only relevent (like
the ->events update) for native metadata.
Signed-off-by: NNeilBrown <neilb@suse.de>
Reported-by: N"Kwolek, Adam" <adam.kwolek@intel.com>

drivers/md/md.c

@@ -2136,16 +2136,6 @@ static void sync_sbs(mddev_t * mddev, int nospares)
 	 * with the rest of the array)
 	 */
 	mdk_rdev_t *rdev;
-
-	/* First make sure individual recovery_offsets are correct */
-	list_for_each_entry(rdev, &mddev->disks, same_set) {
-		if (rdev->raid_disk >= 0 &&
-		    mddev->delta_disks >= 0 &&
-		    !test_bit(In_sync, &rdev->flags) &&
-		    mddev->curr_resync_completed > rdev->recovery_offset)
-				rdev->recovery_offset = mddev->curr_resync_completed;
-
-	}	
 	list_for_each_entry(rdev, &mddev->disks, same_set) {
 		if (rdev->sb_events == mddev->events ||
 		    (nospares &&
@@ -2167,12 +2157,27 @@ static void md_update_sb(mddev_t * mddev, int force_change)
 	int sync_req;
 	int nospares = 0;
 
-	mddev->utime = get_seconds();
-	if (mddev->external)
-		return;
 repeat:
+	/* First make sure individual recovery_offsets are correct */
+	list_for_each_entry(rdev, &mddev->disks, same_set) {
+		if (rdev->raid_disk >= 0 &&
+		    mddev->delta_disks >= 0 &&
+		    !test_bit(In_sync, &rdev->flags) &&
+		    mddev->curr_resync_completed > rdev->recovery_offset)
+				rdev->recovery_offset = mddev->curr_resync_completed;
+
+	}	
+	if (mddev->external || !mddev->persistent) {
+		clear_bit(MD_CHANGE_DEVS, &mddev->flags);
+		clear_bit(MD_CHANGE_CLEAN, &mddev->flags);
+		wake_up(&mddev->sb_wait);
+		return;
+	}
+
 	spin_lock_irq(&mddev->write_lock);
 
+	mddev->utime = get_seconds();
+
 	set_bit(MD_CHANGE_PENDING, &mddev->flags);
 	if (test_and_clear_bit(MD_CHANGE_DEVS, &mddev->flags))
 		force_change = 1;
@@ -2221,19 +2226,6 @@ static void md_update_sb(mddev_t * mddev, int force_change)
 		MD_BUG();
 		mddev->events --;
 	}
-
-	/*
-	 * do not write anything to disk if using
-	 * nonpersistent superblocks
-	 */
-	if (!mddev->persistent) {
-		if (!mddev->external)
-			clear_bit(MD_CHANGE_PENDING, &mddev->flags);
-
-		spin_unlock_irq(&mddev->write_lock);
-		wake_up(&mddev->sb_wait);
-		return;
-	}
 	sync_sbs(mddev, nospares);
 	spin_unlock_irq(&mddev->write_lock);