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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 C5399C5DF62 for ; Wed, 6 Nov 2019 12:06:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 991B92084C for ; Wed, 6 Nov 2019 12:06:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731608AbfKFMGt (ORCPT ); Wed, 6 Nov 2019 07:06:49 -0500 Received: from mx2.suse.de ([195.135.220.15]:42784 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729164AbfKFMGs (ORCPT ); Wed, 6 Nov 2019 07:06:48 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 5D96DB20E; Wed, 6 Nov 2019 12:06:46 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id 433A01E4862; Wed, 6 Nov 2019 13:06:45 +0100 (CET) Date: Wed, 6 Nov 2019 13:06:45 +0100 From: Jan Kara To: Chengguang Xu Cc: Jan Kara , "adilger.kernel" , tytso , Jan Kara , linux-ext4 Subject: Re: [PATCH v2] ext4: choose hardlimit when softlimit is larger than hardlimit in ext4_statfs_project() Message-ID: <20191106120645.GH16085@quack2.suse.cz> References: <20191015102327.5333-1-cgxu519@mykernel.net> <20191015112523.GB29554@quack2.suse.cz> <16e3f00ed3d.da5d5acd1285.2289879597060795256@mykernel.net> <20191106094924.GA16085@quack2.suse.cz> <16e404d465e.ddfd6f53546.5756417115406096069@mykernel.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <16e404d465e.ddfd6f53546.5756417115406096069@mykernel.net> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-ext4-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On Wed 06-11-19 18:40:36, Chengguang Xu wrote: > ---- 在 星期三, 2019-11-06 17:49:24 Jan Kara 撰写 ---- > > On Wed 06-11-19 12:37:35, Chengguang Xu wrote: > > > ---- 在 星期二, 2019-10-15 19:25:23 Jan Kara 撰写 ---- > > > > On Tue 15-10-19 18:23:27, Chengguang Xu wrote: > > > > > Setting softlimit larger than hardlimit seems meaningless > > > > > for disk quota but currently it is allowed. In this case, > > > > > there may be a bit of comfusion for users when they run > > > > > df comamnd to directory which has project quota. > > > > > > > > > > For example, we set 20M softlimit and 10M hardlimit of > > > > > block usage limit for project quota of test_dir(project id 123). > > > > > > > > > > [root@hades mnt_ext4]# repquota -P -a > > > > > *** Report for project quotas on device /dev/loop0 > > > > > Block grace time: 7days; Inode grace time: 7days > > > > > Block limits File limits > > > > > Project used soft hard grace used soft hard grace > > > > > ---------------------------------------------------------------------- > > > > > 0 -- 13 0 0 2 0 0 > > > > > 123 -- 10237 20480 10240 5 200 100 > > > > > > > > > > The result of df command as below: > > > > > > > > > > [root@hades mnt_ext4]# df -h test_dir > > > > > Filesystem Size Used Avail Use% Mounted on > > > > > /dev/loop0 20M 10M 10M 50% /home/cgxu/test/mnt_ext4 > > > > > > > > > > Even though it looks like there is another 10M free space to use, > > > > > if we write new data to diretory test_dir(inherit project id), > > > > > the write will fail with errno(-EDQUOT). > > > > > > > > > > After this patch, the df result looks like below. > > > > > > > > > > [root@hades mnt_ext4]# df -h test_dir > > > > > Filesystem Size Used Avail Use% Mounted on > > > > > /dev/loop0 10M 10M 3.0K 100% /home/cgxu/test/mnt_ext4 > > > > > > > > > > Signed-off-by: Chengguang Xu > > > > > --- > > > > > - Fix a bug in the limit setting logic. > > > > > > > > Thanks for the patch! It looks good to me. You can add: > > > > > > > > Reviewed-by: Jan Kara > > > > > > > > > > Hi Jan, > > > > > > I have a proposal for another direction. > > > Could we add a check for soft limit in quota layer when setting the value? > > > So that we could not bother with specific file systems on statfs(). > > > > What do you mean exactly? To not allow softlimit to be larger than > > hardlimit? That would make some sense but I don't think the risk of > > breaking some user that accidentally depends on current behavior is worth > > the few checks we can save... > > > > Actually, I thought exactly same as you when I wrote my patch for > statfs() of ext4. However, even though softlimit > hardlimit, we cannot > allow user to use blocks or inode more than hardlimit. IOW, the limit is > always there and fixed in this situation. So how about set softlimit > to hardlimit when softlimit > hardlimit and return with success? Well, the softlimit > hardlimit won't have any effect but if the hardlimit is then raised (e.g. with a tool like edquota(8)), it may suddently start having effect. That's why I'm reluctant to just ignore or trim too large softlimit. Honza -- Jan Kara SUSE Labs, CR