raid5: handle io error of batch list

If io error happens in any stripe of a batch list, the batch list will be
split, then normal process will run for the stripes in the list.

Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>
diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
index c8d0004..cf3562e 100644
--- a/drivers/md/raid5.h
+++ b/drivers/md/raid5.h
@@ -336,6 +336,7 @@
 	STRIPE_DISCARD,
 	STRIPE_ON_RELEASE_LIST,
 	STRIPE_BATCH_READY,
+	STRIPE_BATCH_ERR,
 };
 
 /*