raid1: Add a field array_frozen to indicate whether raid in freeze state.

Because the following patch will rewrite the content between normal IO
and resync IO. So we used a parameter to indicate whether raid is in freeze
array.
Signed-off-by: Jianpeng Ma <majianpeng@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>

drivers/md/raid1.c

@@ -829,6 +829,7 @@ static void raise_barrier(struct r1conf *conf)
 
 	/* Now wait for all pending IO to complete */
 	wait_event_lock_irq(conf->wait_barrier,
+			    !conf->array_frozen &&
 			    !conf->nr_pending && conf->barrier < RESYNC_DEPTH,
 			    conf->resync_lock);
 
@@ -860,10 +861,11 @@ static void wait_barrier(struct r1conf *conf)
 		 * count down.
 		 */
 		wait_event_lock_irq(conf->wait_barrier,
-				    !conf->barrier ||
+				    !conf->array_frozen &&
+				    (!conf->barrier ||
 				    (conf->nr_pending &&
 				     current->bio_list &&
-				     !bio_list_empty(current->bio_list)),
+				     !bio_list_empty(current->bio_list))),
 				    conf->resync_lock);
 		conf->nr_waiting--;
 	}
@@ -884,8 +886,7 @@ static void freeze_array(struct r1conf *conf, int extra)
 {
 	/* stop syncio and normal IO and wait for everything to
 	 * go quite.
-	 * We increment barrier and nr_waiting, and then
-	 * wait until nr_pending match nr_queued+extra
+	 * We wait until nr_pending match nr_queued+extra
 	 * This is called in the context of one normal IO request
 	 * that has failed. Thus any sync request that might be pending
 	 * will be blocked by nr_pending, and we need to wait for
@@ -895,8 +896,7 @@ static void freeze_array(struct r1conf *conf, int extra)
 	 * we continue.
 	 */
 	spin_lock_irq(&conf->resync_lock);
-	conf->barrier++;
-	conf->nr_waiting++;
+	conf->array_frozen = 1;
 	wait_event_lock_irq_cmd(conf->wait_barrier,
 				conf->nr_pending == conf->nr_queued+extra,
 				conf->resync_lock,
@@ -907,8 +907,7 @@ static void unfreeze_array(struct r1conf *conf)
 {
 	/* reverse the effect of the freeze */
 	spin_lock_irq(&conf->resync_lock);
-	conf->barrier--;
-	conf->nr_waiting--;
+	conf->array_frozen = 0;
 	wake_up(&conf->wait_barrier);
 	spin_unlock_irq(&conf->resync_lock);
 }

drivers/md/raid1.h

@@ -65,6 +65,7 @@ struct r1conf {
 	int			nr_waiting;
 	int			nr_queued;
 	int			barrier;
+	int			array_frozen;
 
 	/* Set to 1 if a full sync is needed, (fresh device added).
 	 * Cleared when a sync completes.