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=-13.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,FSL_HELO_FAKE,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 6E55AC2D0E4 for ; Tue, 17 Nov 2020 16:40:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 046BF221F1 for ; Tue, 17 Nov 2020 16:40:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="AplUYdKV" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727457AbgKQQkY (ORCPT ); Tue, 17 Nov 2020 11:40:24 -0500 Received: from mail.kernel.org ([198.145.29.99]:33278 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725808AbgKQQkY (ORCPT ); Tue, 17 Nov 2020 11:40:24 -0500 Received: from google.com (unknown [104.132.1.66]) (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 AE6CA21D7E; Tue, 17 Nov 2020 16:40:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1605631224; bh=dVxDFAXp6FT9+XWoqU4EDdf3Oe33FE/vSylhfLqTJVk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=AplUYdKVw+5q2guEA+7SSOzhDI0mbCO+QtVbEflBbv070cX030TV4iVc6rUOziYdB 27J3C+KSf4VJoMOGT0Nk5yUbx4D4xdvGG/KAwfqz3OZScMP4MBGXPAllELo+2XtJhJ kMzl/pywyeWOgjdAhxxyB8m69EHSLWVV/GlQjQRo= Date: Tue, 17 Nov 2020 08:40:21 -0800 From: Jaegeuk Kim To: Chao Yu Cc: linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, kernel-team@android.com, Light Hsieh Subject: Re: [f2fs-dev] [PATCH v3] f2fs: avoid race condition for shinker count Message-ID: <20201117164021.GA1636127@google.com> References: <20201109170012.2129411-1-jaegeuk@kernel.org> <20201112053414.GB3826485@google.com> <20201112054051.GA4092972@google.com> <4aae85c2-1829-06c0-8fd1-4148100dc0b9@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4aae85c2-1829-06c0-8fd1-4148100dc0b9@huawei.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/12, Chao Yu wrote: > On 2020/11/12 13:40, Jaegeuk Kim wrote: > > Light reported sometimes shinker gets nat_cnt < dirty_nat_cnt resulting in > > wrong do_shinker work. Let's avoid to get stale data by using nat_tree_lock. > > > > Reported-by: Light Hsieh > > Signed-off-by: Jaegeuk Kim > > --- > > v3: > > - fix to use NM_I(sbi) > > > > fs/f2fs/shrinker.c | 6 +++++- > > 1 file changed, 5 insertions(+), 1 deletion(-) > > > > diff --git a/fs/f2fs/shrinker.c b/fs/f2fs/shrinker.c > > index d66de5999a26..555712ba06d8 100644 > > --- a/fs/f2fs/shrinker.c > > +++ b/fs/f2fs/shrinker.c > > @@ -18,7 +18,11 @@ static unsigned int shrinker_run_no; > > static unsigned long __count_nat_entries(struct f2fs_sb_info *sbi) > > { > > - long count = NM_I(sbi)->nat_cnt - NM_I(sbi)->dirty_nat_cnt; > > + long count; > > + > > + down_read(&NM_I(sbi)->nat_tree_lock); > > + count = NM_I(sbi)->nat_cnt - NM_I(sbi)->dirty_nat_cnt; > > + up_read(&NM_I(sbi)->nat_tree_lock); > > return count > 0 ? count : 0; > > Minor thing, > > Just return count is enough? since count should never be smaller than 0. Yeah, but let me keep this just in case. > > Anyway, > > Reviewed-by: Chao Yu > > Thanks, > > Thanks, > > > } > >