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=-13.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,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 21745CA9ECB for ; Thu, 31 Oct 2019 18:11:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0432E20650 for ; Thu, 31 Oct 2019 18:11:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729194AbfJaSLe (ORCPT ); Thu, 31 Oct 2019 14:11:34 -0400 Received: from mx2.suse.de ([195.135.220.15]:33062 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729127AbfJaSLd (ORCPT ); Thu, 31 Oct 2019 14:11:33 -0400 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 0E4D6B28C; Thu, 31 Oct 2019 18:11:31 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id A2E791E482D; Thu, 31 Oct 2019 19:11:30 +0100 (CET) Date: Thu, 31 Oct 2019 19:11:30 +0100 From: Jan Kara To: Dmitry Monakhov Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, jack@suse.cz, Dmitry Monakhov Subject: Re: [PATCH 2/2] fs/quota: Check that quota is not dirty before release Message-ID: <20191031181130.GH13321@quack2.suse.cz> References: <20191031103920.3919-1-dmonakhov@openvz.org> <20191031103920.3919-2-dmonakhov@openvz.org> <20191031180033.GF13321@quack2.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191031180033.GF13321@quack2.suse.cz> 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 Thu 31-10-19 19:00:33, Jan Kara wrote: > On Thu 31-10-19 10:39:20, Dmitry Monakhov wrote: > > From: Dmitry Monakhov > > > > There is a race window where quota was redirted once we drop dq_list_lock inside dqput(), > > but before we grab dquot->dq_lock inside dquot_release() > > > > TASK1 TASK2 (chowner) > > ->dqput() > > we_slept: > > spin_lock(&dq_list_lock) > > if (dquot_dirty(dquot)) { > > spin_unlock(&dq_list_lock); > > dquot->dq_sb->dq_op->write_dquot(dquot); > > goto we_slept > > if (test_bit(DQ_ACTIVE_B, &dquot->dq_flags)) { > > spin_unlock(&dq_list_lock); > > dquot->dq_sb->dq_op->release_dquot(dquot); > > dqget() > > mark_dquot_dirty() > > dqput() > > goto we_slept; > > } > > So dquot dirty quota will be released by TASK1, but on next we_sleept loop > > we detect this and call ->write_dquot() for it. > > XFSTEST: https://github.com/dmonakhov/xfstests/commit/440a80d4cbb39e9234df4d7240aee1d551c36107 > > Yeah, good catch. Both patches look good to me. I've added them to my tree. And forgot to add: Thanks for both patches and also the regression tests! I really appreciate it! Honza > > Signed-off-by: Dmitry Monakhov > > --- > > fs/ocfs2/quota_global.c | 2 +- > > fs/quota/dquot.c | 2 +- > > include/linux/quotaops.h | 10 ++++++++++ > > 3 files changed, 12 insertions(+), 2 deletions(-) > > > > diff --git a/fs/ocfs2/quota_global.c b/fs/ocfs2/quota_global.c > > index 7a92219..eda8348 100644 > > --- a/fs/ocfs2/quota_global.c > > +++ b/fs/ocfs2/quota_global.c > > @@ -728,7 +728,7 @@ static int ocfs2_release_dquot(struct dquot *dquot) > > > > mutex_lock(&dquot->dq_lock); > > /* Check whether we are not racing with some other dqget() */ > > - if (atomic_read(&dquot->dq_count) > 1) > > + if (dquot_is_busy(dquot)) > > goto out; > > /* Running from downconvert thread? Postpone quota processing to wq */ > > if (current == osb->dc_task) { > > diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c > > index b492b9e..72d24a5 100644 > > --- a/fs/quota/dquot.c > > +++ b/fs/quota/dquot.c > > @@ -497,7 +497,7 @@ int dquot_release(struct dquot *dquot) > > > > mutex_lock(&dquot->dq_lock); > > /* Check whether we are not racing with some other dqget() */ > > - if (atomic_read(&dquot->dq_count) > 1) > > + if (dquot_is_busy(dquot)) > > goto out_dqlock; > > if (dqopt->ops[dquot->dq_id.type]->release_dqblk) { > > ret = dqopt->ops[dquot->dq_id.type]->release_dqblk(dquot); > > diff --git a/include/linux/quotaops.h b/include/linux/quotaops.h > > index 185d948..91e0b76 100644 > > --- a/include/linux/quotaops.h > > +++ b/include/linux/quotaops.h > > @@ -54,6 +54,16 @@ static inline struct dquot *dqgrab(struct dquot *dquot) > > atomic_inc(&dquot->dq_count); > > return dquot; > > } > > + > > +static inline bool dquot_is_busy(struct dquot *dquot) > > +{ > > + if (test_bit(DQ_MOD_B, &dquot->dq_flags)) > > + return true; > > + if (atomic_read(&dquot->dq_count) > 1) > > + return true; > > + return false; > > +} > > + > > void dqput(struct dquot *dquot); > > int dquot_scan_active(struct super_block *sb, > > int (*fn)(struct dquot *dquot, unsigned long priv), > > -- > > 2.7.4 > > > -- > Jan Kara > SUSE Labs, CR -- Jan Kara SUSE Labs, CR