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=-3.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 D8467C433E1 for ; Thu, 30 Jul 2020 14:15:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B6FF621744 for ; Thu, 30 Jul 2020 14:15:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="N2Sm8Dqf" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728345AbgG3OP4 (ORCPT ); Thu, 30 Jul 2020 10:15:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53184 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726772AbgG3OP4 (ORCPT ); Thu, 30 Jul 2020 10:15:56 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0B4D8C061574; Thu, 30 Jul 2020 07:15:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=tFNWyA6j56ec9aeIQ1OfZZxIge2UH4uedAgETJaYKbk=; b=N2Sm8DqfAr9tzEPQRhtlTBh2Mx tox4OdA1mARnf8x6r2/doq8NQd/GK/8iZDaje/7XsV8tbwggyoq2W1S2ygXyLajpTKjcJd9QFE7rs SG61EIoHG6EpfY4BgVOz9hO0M1JZQjS1CRYviOqKcNgj8f1nPY4fHN04NSa+ftWDiRksAGdy4Baf4 OBjvH33Y6L478WA5eYEArJ+5CAbHYsIps4st0nzh3UnqJd3UsrO4DVgi94MT4ICnRAUBZVLoepWOa UqNbmygbtOqjvdev2rJApy35V0Pw68ULJKAwZABa5LKAIJ6et1rjNYrF1qv9XSikbQvyvTkKWndGQ OdGEycIg==; Received: from willy by casper.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1k19LN-0002N9-GX; Thu, 30 Jul 2020 14:15:37 +0000 Date: Thu, 30 Jul 2020 15:15:37 +0100 From: Matthew Wilcox To: Kirill Tkhai 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 Subject: Re: [PATCH 09/23] ns: Introduce ns_idr to be able to iterate all allocated namespaces in the system Message-ID: <20200730141537.GF23808@casper.infradead.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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1e41ae9d-9c3d-1c4a-d49e-b7f660ce99f7@virtuozzo.com> Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org 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.