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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0FE0FEB64D9 for ; Thu, 29 Jun 2023 11:10:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232177AbjF2LK4 (ORCPT ); Thu, 29 Jun 2023 07:10:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37636 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231842AbjF2LKx (ORCPT ); Thu, 29 Jun 2023 07:10:53 -0400 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4B79C10CF; Thu, 29 Jun 2023 04:10:51 -0700 (PDT) Received: from dggpeml500021.china.huawei.com (unknown [172.30.72.53]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4QsFzl64BgzqVFd; Thu, 29 Jun 2023 19:08:03 +0800 (CST) Received: from [10.174.177.174] (10.174.177.174) by dggpeml500021.china.huawei.com (7.185.36.21) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.27; Thu, 29 Jun 2023 19:10:48 +0800 Message-ID: Date: Thu, 29 Jun 2023 19:10:47 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.1.2 Subject: Re: [PATCH v2 2/7] quota: add new global dquot list releasing_dquots Content-Language: en-US To: Jan Kara CC: , , , , , , , Baokun Li References: <20230628132155.1560425-1-libaokun1@huawei.com> <20230628132155.1560425-3-libaokun1@huawei.com> <20230629102952.ifn3qdoh632ybsb5@quack3> From: Baokun Li In-Reply-To: <20230629102952.ifn3qdoh632ybsb5@quack3> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.177.174] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To dggpeml500021.china.huawei.com (7.185.36.21) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On 2023/6/29 18:29, Jan Kara wrote: > On Wed 28-06-23 21:21:50, Baokun Li wrote: >> Add a new global dquot list that obeys the following rules: >> >> 1). A dquot is added to this list when its last reference count is about >> to be dropped. >> 2). The reference count of the dquot in the list is greater than or equal >> to 1 ( due to possible race with dqget()). >> 3). When a dquot is removed from this list, a reference count is always >> subtracted, and if the reference count is then 0, the dquot is added >> to the free_dquots list. >> >> This list is used to safely perform the final cleanup before releasing >> the last reference count, to avoid various contention issues caused by >> performing cleanup directly in dqput(), and to avoid the performance impact >> caused by calling synchronize_srcu(&dquot_srcu) directly in dqput(). Here >> it is just defining the list and implementing the corresponding operation >> function, which we will use later. >> >> Suggested-by: Jan Kara >> Signed-off-by: Baokun Li > I think you can merge this patch with patch 5. It is not like separating > this bit helps in review or anything... OK, I just don't want to cram a lot of stuff into patch 5, I will merge this patch into patch 5 in the next version. >> diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c >> index 108ba9f1e420..a8b43b5b5623 100644 >> --- a/fs/quota/dquot.c >> +++ b/fs/quota/dquot.c >> @@ -226,12 +226,21 @@ static void put_quota_format(struct quota_format_type *fmt) >> /* >> * Dquot List Management: >> * The quota code uses four lists for dquot management: the inuse_list, > ^^^ five now :) Yes, indeed, I forgot to correct here. > >> - * free_dquots, dqi_dirty_list, and dquot_hash[] array. A single dquot >> - * structure may be on some of those lists, depending on its current state. >> + * releasing_dquots, free_dquots, dqi_dirty_list, and dquot_hash[] array. >> + * A single dquot structure may be on some of those lists, depending on >> + * its current state. >> * >> * All dquots are placed to the end of inuse_list when first created, and this >> * list is used for invalidate operation, which must look at every dquot. >> * >> + * When the last reference of a dquot will be dropped, the dquot will be >> + * added to releasing_dquots. We'd then queue work item which would call >> + * synchronize_srcu() and after that perform the final cleanup of all the >> + * dquots on the list. Both releasing_dquots and free_dquots use the >> + * dq_free list_head in the dquot struct. when a dquot is removed from > ^^^ Capital W please Good catch！Very sorry for the oversight here. >> + * releasing_dquots, a reference count is always subtracted, and if >> + * dq_count == 0 at that point, the dquot will be added to the free_dquots. >> + * > Honza Thank you very much for your careful REVIEW! I will fix those in the next version! -- With Best Regards, Baokun Li .