f2fs: fix to skip shrinking extent nodes

In f2fs_shrink_extent_tree we should stop shrink flow if we have already
shrunk enough nodes in extent cache.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/extent_cache.c b/fs/f2fs/extent_cache.c
index a38ee9b..7ddba81 100644
--- a/fs/f2fs/extent_cache.c
+++ b/fs/f2fs/extent_cache.c
@@ -620,7 +620,7 @@
 			write_unlock(&et->lock);
 
 			if (node_cnt + tree_cnt >= nr_shrink)
-				break;
+				goto unlock_out;
 		}
 	}
 unlock_out: