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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 33646C43142 for ; Tue, 31 Jul 2018 04:16:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DEFC320840 for ; Tue, 31 Jul 2018 04:16:46 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DEFC320840 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ZenIV.linux.org.uk 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 S1727454AbeGaFzA (ORCPT ); Tue, 31 Jul 2018 01:55:00 -0400 Received: from zeniv.linux.org.uk ([195.92.253.2]:60806 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726071AbeGaFzA (ORCPT ); Tue, 31 Jul 2018 01:55:00 -0400 Received: from viro by ZenIV.linux.org.uk with local (Exim 4.87 #1 (Red Hat Linux)) id 1fkM5S-00015w-Ou; Tue, 31 Jul 2018 04:16:42 +0000 Date: Tue, 31 Jul 2018 05:16:42 +0100 From: Al Viro To: David Howells Cc: linux-api@vger.kernel.org, torvalds@linux-foundation.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 34/38] vfs: syscall: Add fsinfo() to query filesystem information [ver #10] Message-ID: <20180731041642.GH30522@ZenIV.linux.org.uk> References: <153271267980.9458.7640156373438016898.stgit@warthog.procyon.org.uk> <153271291017.9458.7827028432894772673.stgit@warthog.procyon.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <153271291017.9458.7827028432894772673.stgit@warthog.procyon.org.uk> User-Agent: Mutt/1.9.1 (2017-09-22) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jul 27, 2018 at 06:35:10PM +0100, David Howells wrote: > params->request indicates the attribute/attributes to be queried. This can > be one of: > > fsinfo_attr_statfs - statfs-style info > fsinfo_attr_fsinfo - Information about fsinfo() > fsinfo_attr_ids - Filesystem IDs > fsinfo_attr_limits - Filesystem limits > fsinfo_attr_supports - What's supported in statx(), IOC flags > fsinfo_attr_capabilities - Filesystem capabilities > fsinfo_attr_timestamp_info - Inode timestamp info > fsinfo_attr_volume_id - Volume ID (string) > fsinfo_attr_volume_uuid - Volume UUID > fsinfo_attr_volume_name - Volume name (string) > fsinfo_attr_cell_name - Cell name (string) > fsinfo_attr_domain_name - Domain name (string) > fsinfo_attr_realm_name - Realm name (string) > fsinfo_attr_server_name - Name of the Nth server (string) > fsinfo_attr_server_address - Mth address of the Nth server > fsinfo_attr_parameter - Nth mount parameter (string) > fsinfo_attr_source - Nth mount source name (string) > fsinfo_attr_name_encoding - Filename encoding (string) > fsinfo_attr_name_codepage - Filename codepage (string) > fsinfo_attr_io_size - I/O size hints Umm... What's so special about cell/volume/domain/realm? And what do we do when a random filesystem gets added - should its parameters go into catch-all pile (attr_parameter), or should they get classes of their own? For Cthulhu sake, who's going to maintain that enum in face of random out-of-tree filesystems, each wanting a class or two its own? We'd tried that with device numbers; ask hpa how well has that worked and how much did he love the whole experience...