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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 0AF0FC35247 for ; Tue, 4 Feb 2020 16:07:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CCE8B20730 for ; Tue, 4 Feb 2020 16:07:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727378AbgBDQHL (ORCPT ); Tue, 4 Feb 2020 11:07:11 -0500 Received: from mx2.suse.de ([195.135.220.15]:49532 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727308AbgBDQHL (ORCPT ); Tue, 4 Feb 2020 11:07:11 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id B4A04AC65; Tue, 4 Feb 2020 16:07:09 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id A66E31E0BAA; Tue, 4 Feb 2020 17:07:03 +0100 (CET) Date: Tue, 4 Feb 2020 17:07:03 +0100 From: Jan Kara To: "Mainz, Roland" Cc: Sascha Hauer , Jan Kara , "linux-fsdevel@vger.kernel.org" , Richard Weinberger , "linux-mtd@lists.infradead.org" , "kernel@pengutronix.de" , Jan Kara Subject: Re: Implementing quota support on Linux without block device as backing store ? / was: RE: [PATCH 1/8] quota: Allow to pass mount path to quotactl Message-ID: <20200204160703.GG2388@quack2.suse.cz> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Tue 04-02-20 15:07:31, Mainz, Roland wrote: > Sascha Hauer wrote: > > This patch introduces the Q_PATH flag to the quotactl cmd argument. > > When given, the path given in the special argument to quotactl will be the > > mount path where the filesystem is mounted, instead of a path to the block > > device. > > This is necessary for filesystems which do not have a block device as backing > > store. Particularly this is done for upcoming UBIFS support. > > Just curious: Did you check how NFSv4 (also a filesystem without block > device as backing store...) implemented quota support ? Maybe there is > already a solution... Well, NFS does not really implement quota support. It relies on the server (i.e., a local filesystem on the server) for quota tracking and enforcement and the NFS client just gets the EDQUOT error the server got from the filesystem. And for quota querrying (e.g. quota(1) command) there is a special sideband rpc protocol handled by the quota tools. With NFSv4 there is some support in the protocol itself for quota reporting but in Linux this is not really supported because it does not map well to how Linux does quotas. Honza -- Jan Kara SUSE Labs, CR