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 3F1EEC433DF for ; Wed, 12 Aug 2020 14:24:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0302A20639 for ; Wed, 12 Aug 2020 14:24:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="jWXDnfjE" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726685AbgHLOYD (ORCPT ); Wed, 12 Aug 2020 10:24:03 -0400 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:40682 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726485AbgHLOYB (ORCPT ); Wed, 12 Aug 2020 10:24:01 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1597242240; 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=jWXDnfjE4wqOn4bEEvXdXlupZOFftiU128aNgDaIGXvYs8AGEnxjvDzJJLigFcQcP4NKyr D1GSoAcVrVywDEfUi4M4dXj9fzoegBgHEEyY6xstDjCofxkEyFwjcHNSH4XRq1DPNe5veq /rTpwZDzUsmR0mLZ/Wr6XT2Z1WsjQQU= 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: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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