Btrfs: Fixup last found extent caching

Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 4a7bc4e..518326f 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -54,6 +54,7 @@
 	struct tree_buffer *commit_root;
 	struct ctree_root *extent_root;
 	struct key current_insert;
+	struct key last_insert;
 	int fp;
 	struct radix_tree_root cache_radix;
 	struct radix_tree_root pinned_radix;