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=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS,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 AC023C433DB for ; Thu, 18 Mar 2021 20:37:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6C3B664F38 for ; Thu, 18 Mar 2021 20:37:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230368AbhCRUgk (ORCPT ); Thu, 18 Mar 2021 16:36:40 -0400 Received: from mx2.suse.de ([195.135.220.15]:47436 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229958AbhCRUgS (ORCPT ); Thu, 18 Mar 2021 16:36:18 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 542C1AD4A; Thu, 18 Mar 2021 20:36:17 +0000 (UTC) Received: by ds.suse.cz (Postfix, from userid 10065) id A9A0CDA6E2; Thu, 18 Mar 2021 21:34:14 +0100 (CET) Date: Thu, 18 Mar 2021 21:34:14 +0100 From: David Sterba To: Sidong Yang Cc: dsterba@suse.cz, linux-btrfs@vger.kernel.org, Qu Wenruo Subject: Re: [PATCH v2] btrfs-progs: common: make sure that qgroup id is in range Message-ID: <20210318203414.GB7604@twin.jikos.cz> Reply-To: dsterba@suse.cz Mail-Followup-To: dsterba@suse.cz, Sidong Yang , linux-btrfs@vger.kernel.org, Qu Wenruo References: <20210316132746.19979-1-realwakka@gmail.com> <20210317183647.GW7604@twin.jikos.cz> <20210318022208.GA34562@realwakka> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210318022208.GA34562@realwakka> User-Agent: Mutt/1.5.23.1-rc1 (2014-03-12) Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Thu, Mar 18, 2021 at 02:22:20AM +0000, Sidong Yang wrote: > On Wed, Mar 17, 2021 at 07:36:47PM +0100, David Sterba wrote: > > On Tue, Mar 16, 2021 at 01:27:46PM +0000, Sidong Yang wrote: > > > When user assign qgroup with qgroup id that is too big to exceeds > > > range and invade level value, and it works without any error. but > > > this action would be make undefined error. this code make sure that > > > qgroup id doesn't exceed range(0 ~ 2^48-1). > > > > Should the level be also validate? The function parse_qgroupid does not > > do full validation, so eg 0//0 would be parsed as a path and not as a > > typo, level larger than 64K will be silently clamped. > > I agree. 0//0 would be parsed as path but it failed in > btrfs_util_is_subvolume() and goes to err. I understand that upper 16 > bits of qgroupid is for level. so, The valid llevel range is [0~2^16-1]. > But I can't get it that level larger than 64K will be clampled. The way the level gets stored into the final qgroup id is level << 48. For example invalid values 70000/281474976710779 would be stored as subvol id 123 and level 4465, where the u64 is 0x117100000000007b > one more question about that, I see that the ioctl calls just store the > qgroupid without any opeartion with level. is the level meaningless in > kernel? The quota groups are hierarchical and the level denotes the level, where 0/subvolid is the lowest always attached to a subvolume and the higher levels are artificial and may contain any qgroups and do the whole accounting on the subtree. The original design doc .pdf can be found in https://git.kernel.org/pub/scm/linux/kernel/git/arne/qgroups-doc.git/tree/