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>
(cherry picked from commit 6976a6f2)
Signed-off-by: Willy Tarreau <w@1wt.eu>

fs/ext4/namei.c

@@ -1457,6 +1457,10 @@ static int make_indexed_dir(handle_t *handle, struct dentry *dentry,
 	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) {
 		/*
@@ -1465,8 +1469,6 @@ static int make_indexed_dir(handle_t *handle, struct dentry *dentry,
 		 * 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;
 	}