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=-2.3 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 1FE20C47F83 for ; Thu, 12 Jul 2018 17:20:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D28F92086E for ; Thu, 12 Jul 2018 17:20:30 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D28F92086E 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 S1732579AbeGLRa5 (ORCPT ); Thu, 12 Jul 2018 13:30:57 -0400 Received: from zeniv.linux.org.uk ([195.92.253.2]:42102 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727136AbeGLRa5 (ORCPT ); Thu, 12 Jul 2018 13:30:57 -0400 Received: from viro by ZenIV.linux.org.uk with local (Exim 4.87 #1 (Red Hat Linux)) id 1fdfGS-0002Qc-Q9; Thu, 12 Jul 2018 17:20:24 +0000 Date: Thu, 12 Jul 2018 18:20:24 +0100 From: Al Viro To: Greg KH Cc: David Howells , linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org, torvalds@linux-foundation.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 24/32] vfs: syscall: Add fsopen() to prepare for superblock creation [ver #9] Message-ID: <20180712172024.GZ30522@ZenIV.linux.org.uk> References: <153126248868.14533.9751473662727327569.stgit@warthog.procyon.org.uk> <153126264966.14533.3388004240803696769.stgit@warthog.procyon.org.uk> <20180712171505.GA23780@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180712171505.GA23780@kroah.com> 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 Thu, Jul 12, 2018 at 07:15:05PM +0200, Greg KH wrote: > On Tue, Jul 10, 2018 at 11:44:09PM +0100, David Howells wrote: > > Provide an fsopen() system call that starts the process of preparing to > > create a superblock that will then be mountable, using an fd as a context > > handle. fsopen() is given the name of the filesystem that will be used: > > > > int mfd = fsopen(const char *fsname, unsigned int flags); > > > > where flags can be 0 or FSOPEN_CLOEXEC. > > > > For example: > > > > sfd = fsopen("ext4", FSOPEN_CLOEXEC); > > write(sfd, "s /dev/sdb1"); // note I'm ignoring write's length arg > > write(sfd, "o noatime"); > > write(sfd, "o acl"); > > write(sfd, "o user_attr"); > > write(sfd, "o iversion"); > > write(sfd, "o "); > > write(sfd, "r /my/container"); // root inside the fs > > write(sfd, "x create"); // create the superblock > > Ugh, creating configfs again in a syscall form? I know people love > file descriptors, but can't you do this with a configfs entry instead if > you really want to do this type of thing from userspace in this type of > "style"? > > Why reinvent the wheel again? The damn thing REALLY, REALLY depends upon the fs type. How would you map it on configfs?