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=-4.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 BD649C433DF for ; Wed, 12 Aug 2020 14:24:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9278720639 for ; Wed, 12 Aug 2020 14:24:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Zfgarcwe" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726564AbgHLOYJ (ORCPT ); Wed, 12 Aug 2020 10:24:09 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:51407 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726680AbgHLOYE (ORCPT ); Wed, 12 Aug 2020 10:24:04 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1597242242; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=xF1PzXjpzf3p7zUDwOJiId7wF1Lsnzi9qAduhzfHZOs=; b=ZfgarcweGQzfDfwIyh+mNyZ7H3yH5Kyy0MOkkAFrxHdUMbZEEh9OAXBMXYwv6b9+UghmwB srhrmiAPB7549HuFtT6hZbc5NNrrBMSl2wNICckpFElAM64nI5Y/DgQiTBR3driZraA3EW +hX31Md+j/ExfIGVivKG//cX+e4nXB4= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-309-gt8_i8atP8K4P7OsjX-rFQ-1; Wed, 12 Aug 2020 10:23:59 -0400 X-MC-Unique: gt8_i8atP8K4P7OsjX-rFQ-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id B6D6F101C8A5; Wed, 12 Aug 2020 14:23:56 +0000 (UTC) Received: from warthog.procyon.org.uk (ovpn-120-127.rdu2.redhat.com [10.10.120.127]) by smtp.corp.redhat.com (Postfix) with ESMTP id B129F5D6BD; Wed, 12 Aug 2020 14:23:53 +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: References: <1842689.1596468469@warthog.procyon.org.uk> <1845353.1596469795@warthog.procyon.org.uk> <20200811135419.GA1263716@miu.piliscsaba.redhat.com> <135551.1597240486@warthog.procyon.org.uk> To: Miklos Szeredi Cc: dhowells@redhat.com, Linus Torvalds , linux-fsdevel , Al Viro , Karel Zak , Jeff Layton , Miklos Szeredi , Nicolas Dichtel , Christian Brauner , Lennart Poettering , Linux API , Ian Kent , LSM , Linux Kernel Mailing List Subject: Re: file metadata via fs API (was: [GIT PULL] Filesystem Information) MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <137928.1597242232.1@warthog.procyon.org.uk> Date: Wed, 12 Aug 2020 15:23:52 +0100 Message-ID: <137929.1597242232@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: Miklos Szeredi wrote: > The point is that generic operations already exist and no need to add > new, specialized ones to access metadata. open and read already exist, yes, but the metadata isn't currently in convenient inodes and dentries that you can just walk through. So you're going to end up with a specialised filesystem instead, I suspect. Basically, it's the same as your do-everything-through-/proc/self/fds/ approach. And it's going to be heavier. I don't know if you're planning on creating a superblock each time you do an O_ALT open, but you will end up creating some inodes, dentries and a file - even before you get to the reading bit. David