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=-6.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 C7203C433E0 for ; Thu, 30 Jul 2020 14:20:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B1BDF20829 for ; Thu, 30 Jul 2020 14:20:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729297AbgG3OU3 (ORCPT ); Thu, 30 Jul 2020 10:20:29 -0400 Received: from relay.sw.ru ([185.231.240.75]:36104 "EHLO relay3.sw.ru" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729278AbgG3OU2 (ORCPT ); Thu, 30 Jul 2020 10:20:28 -0400 Received: from [192.168.15.64] by relay3.sw.ru with esmtp (Exim 4.93) (envelope-from ) id 1k19Pl-0004HY-BC; Thu, 30 Jul 2020 17:20:09 +0300 Subject: Re: [PATCH 09/23] ns: Introduce ns_idr to be able to iterate all allocated namespaces in the system To: Matthew Wilcox Cc: viro@zeniv.linux.org.uk, adobriyan@gmail.com, davem@davemloft.net, ebiederm@xmission.com, akpm@linux-foundation.org, christian.brauner@ubuntu.com, areber@redhat.com, serge@hallyn.com, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org References: <159611007271.535980.15362304262237658692.stgit@localhost.localdomain> <159611040870.535980.13460189038999722608.stgit@localhost.localdomain> <20200730122319.GC23808@casper.infradead.org> <485c01e6-a4ee-5076-878e-6303e6d8d5f3@virtuozzo.com> <20200730135640.GE23808@casper.infradead.org> <1e41ae9d-9c3d-1c4a-d49e-b7f660ce99f7@virtuozzo.com> <20200730141537.GF23808@casper.infradead.org> From: Kirill Tkhai Message-ID: <544847e2-4771-9344-e840-5f394fa3df8a@virtuozzo.com> Date: Thu, 30 Jul 2020 17:20:23 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20200730141537.GF23808@casper.infradead.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On 30.07.2020 17:15, Matthew Wilcox wrote: > On Thu, Jul 30, 2020 at 05:12:09PM +0300, Kirill Tkhai wrote: >> On 30.07.2020 16:56, Matthew Wilcox wrote: >>> On Thu, Jul 30, 2020 at 04:32:22PM +0300, Kirill Tkhai wrote: >>>> On 30.07.2020 15:23, Matthew Wilcox wrote: >>>>> xa_erase_irqsave(); >>>> >>>> static inline void *xa_erase_irqsave(struct xarray *xa, unsigned long index) >>>> { >>>> unsigned long flags; >>>> void *entry; >>>> >>>> xa_lock_irqsave(xa, flags); >>>> entry = __xa_erase(xa, index); >>>> xa_unlock_irqrestore(xa, flags); >>>> >>>> return entry; >>>> } >>> >>> was there a question here? >> >> No, I just I will add this in separate patch. > > Ah, yes. Thanks! > >>>>>> +struct ns_common *ns_get_next(unsigned int *id) >>>>>> +{ >>>>>> + struct ns_common *ns; >>>>>> + >>>>>> + if (*id < PROC_NS_MIN_INO - 1) >>>>>> + *id = PROC_NS_MIN_INO - 1; >>>>>> + >>>>>> + *id += 1; >>>>>> + *id -= PROC_NS_MIN_INO; >>>>>> + >>>>>> + rcu_read_lock(); >>>>>> + do { >>>>>> + ns = idr_get_next(&ns_idr, id); >>>>>> + if (!ns) >>>>>> + break; >>>>> >>>>> xa_find_after(); >>>>> >>>>> You'll want a temporary unsigned long to work with ... >>>>> >>>>>> + if (!refcount_inc_not_zero(&ns->count)) { >>>>>> + ns = NULL; >>>>>> + *id += 1; >>>>> >>>>> you won't need this increment. >>>> >>>> Why? I don't see a way xarray allows to avoid this. >>> >>> It's embedded in xa_find_after(). >> >> How is it embedded to check ns->count that it knows nothing? > > I meant you won't need to increment '*id'. The refcount is, of course, > your business. Ok, this brings comfort to me, because first time I thought xarray is a big brother, which knows everything about my counters :)