From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B591CECDE5F for ; Thu, 19 Jul 2018 08:09:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6AFCC20693 for ; Thu, 19 Jul 2018 08:09:23 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6AFCC20693 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731581AbeGSIvR (ORCPT ); Thu, 19 Jul 2018 04:51:17 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:38442 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1731391AbeGSIvQ (ORCPT ); Thu, 19 Jul 2018 04:51:16 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 4F13440201CA; Thu, 19 Jul 2018 08:09:20 +0000 (UTC) Received: from warthog.procyon.org.uk (ovpn-120-116.rdu2.redhat.com [10.10.120.116]) by smtp.corp.redhat.com (Postfix) with ESMTP id 7A2D72026D6B; Thu, 19 Jul 2018 08:09:19 +0000 (UTC) Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <20180718154637.31878-1-mszeredi@redhat.com> References: <20180718154637.31878-1-mszeredi@redhat.com> To: Miklos Szeredi Cc: dhowells@redhat.com, Al Viro , linux-unionfs@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH] vfs: make open_with_fake_path() not contribute to nr_files MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <18288.1531987758.1@warthog.procyon.org.uk> Date: Thu, 19 Jul 2018 09:09:18 +0100 Message-ID: <18289.1531987758@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 2.78 on 10.11.54.4 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.6]); Thu, 19 Jul 2018 08:09:20 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.6]); Thu, 19 Jul 2018 08:09:20 +0000 (UTC) for IP:'10.11.54.4' DOMAIN:'int-mx04.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'dhowells@redhat.com' RCPT:'' Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Miklos Szeredi wrote: > Stacking file operations in overlay will store an extra open file for each > overlay file opened. > > The overhead is just that of "struct file" which is about 256bytes, because > overlay already pins an extra dentry and inode when the file is open, which > add up to a much larger overhead. > > For fear of breaking working setups, don't start accounting the extra file. Sounds useful for cachefiles too, though Christoph Hellwig objected strongly last time I tried this, so you might want to check with him directly. David