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=-4.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,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 086E3C433F2 for ; Wed, 22 Jul 2020 19:10:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DB95B20787 for ; Wed, 22 Jul 2020 19:10:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595445025; bh=+t3jY0IpTJCIfsWEdsuY3x3kM796R1C8EohXWaLiw9Y=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=AkTSXTzJU3F0muACgGHJeoR1Wrwg1NEMOZJPsUZ7lcNVQdRJyPHaFH+TbniR7wH/+ 7dSs3BefMQDfkDXP/e342V8zJDjQpEyKzCAwSmlh8K2YJ1UcMpyhmUDMJKjwzVCIHm i278WL/TbFkppaNnIaPjAxYgYXk+i+b+w3xemgyk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732628AbgGVTKY (ORCPT ); Wed, 22 Jul 2020 15:10:24 -0400 Received: from mail.kernel.org ([198.145.29.99]:53920 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732575AbgGVTKV (ORCPT ); Wed, 22 Jul 2020 15:10:21 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 9A34E204EA; Wed, 22 Jul 2020 19:10:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595445021; bh=+t3jY0IpTJCIfsWEdsuY3x3kM796R1C8EohXWaLiw9Y=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ebBukWMp5zxK6NJqb9nkijuy9EKOVU5lqYjUPomAlvOI+/ju8xrtyp6vOWZjcZpDT c3Qz1bSqDg5ljLRcS6+tBZHWGkz/PHcnaOAakmgFGT0PzLBBNPrFLqsBY6kA45UDdL 0yg53bLhy0ZvdZ5lnTPO56hUnUzhVcNbGyDroYiA= Date: Wed, 22 Jul 2020 21:10:26 +0200 From: Greg KH To: Jaegeuk Kim Cc: Daeho Jeong , linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, kernel-team@android.com, Daeho Jeong Subject: Re: [PATCH 1/2] f2fs: add sysfs symbolic link to kobject with volume name Message-ID: <20200722191026.GA583549@kroah.com> References: <20200719054409.3050516-1-daeho43@gmail.com> <20200719151640.GA301791@kroah.com> <20200722164356.GA3912099@google.com> <20200722170602.GA440171@kroah.com> <20200722172437.GH3912099@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20200722172437.GH3912099@google.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 22, 2020 at 10:24:37AM -0700, Jaegeuk Kim wrote: > On 07/22, Greg KH wrote: > > On Wed, Jul 22, 2020 at 09:43:56AM -0700, Jaegeuk Kim wrote: > > > On 07/19, Greg KH wrote: > > > > On Sun, Jul 19, 2020 at 02:44:08PM +0900, Daeho Jeong wrote: > > > > > From: Daeho Jeong > > > > > > > > > > Added a symbolic link directory pointing to its device name > > > > > directory using the volume name of the partition in sysfs. > > > > > (i.e., /sys/fs/f2fs/vol_#x -> /sys/fs/f2fs/sda1) > > > > > > > > No, please no. > > > > > > > > That is already created today for you in /dev/disk/ The kernel does not > > > > need to do this again. > > > > > > > > If your distro/system/whatever does not provide you with /dev/disk/ and > > > > all of the symlinks in there, then work with your distro/system/whatever > > > > to do so. > > > > > > I don't get the point, since /dev/disk points device node, not any sysfs entry. > > > Do you mean we need to create symlink to /sys/fs/f2fs/dm-X in /dev/disk? > > > > Huh, no! It's all done for you today automagically by userspace: > > > > $ tree /dev/disk/by-label/ > > /dev/disk/by-label/ > > ├── boot -> ../../sda1 > > ├── fast_disk -> ../../md0 > > ├── root -> ../../sda2 > > └── stuff -> ../../dm-0 > > > > Look on your laptop/desktop/server today for those, there's lots of > > symlinks in /dev/disk/ > > What I mean is "creating symlink from *userspace*", but the concern is > "/dev/" looks like being used for device nodes only, not sysfs. That is correct, that is what /dev/ is for, not sysfs. > > > > Again, no need to do this on a per-filesystem-basis when we already have > > > > this around for all filesystems, and have had it for 15+ years now. > > > > > > Could you point out where we can get this? And, the label support depends > > > on per-filesystem design. I'm not sure how this can be generic enough. > > > > Userspace knows how to read labels on a per-filesystem-basis and does so > > just fine. That's how it creates those symlinks, no kernel support is > > needed. > > > > This has been implemented for 15+ years now, it's not a new thing... > > > > Now if your embedded system doesn't support it, that's the userspace of > > that system's fault, it's not the kernel's fault at all. Go fix your > > userspace if you want those things. > > I'm not talking about whose fault tho. :) By any chance, could you please > suggest a good location to create a symlink for this sysfs entry? There is no need for such a sysfs entry, that's what I am trying to say. Userspace already has all of the needed information here, do not try to add filesystem-specific stuff like this, unless you somehow are going to do it for all filesystems :) thanks, gregt k-h