ext4: don't dereference null pointer when make_indexed_dir() fails

Fix for a null pointer bug found while running punch hole tests

Signed-off-by: Allison Henderson <achender@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 3c7a06e..b754b77 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -1413,6 +1413,10 @@
 	frame->at = entries;
 	frame->bh = bh;
 	bh = bh2;
+
+	ext4_handle_dirty_metadata(handle, dir, frame->bh);
+	ext4_handle_dirty_metadata(handle, dir, bh);
+
 	de = do_split(handle,dir, &bh, frame, &hinfo, &retval);
 	if (!de) {
 		/*
@@ -1421,8 +1425,6 @@
 		 * with corrupted filesystem.
 		 */
 		ext4_mark_inode_dirty(handle, dir);
-		ext4_handle_dirty_metadata(handle, dir, frame->bh);
-		ext4_handle_dirty_metadata(handle, dir, bh);
 		dx_release(frames);
 		return retval;
 	}