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=-0.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 1CED1C2D0C9 for ; Fri, 13 Dec 2019 21:19:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 898BD20663 for ; Fri, 13 Dec 2019 21:19:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726792AbfLMVTt (ORCPT ); Fri, 13 Dec 2019 16:19:49 -0500 Received: from mout.kundenserver.de ([212.227.126.133]:56469 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725554AbfLMVTt (ORCPT ); Fri, 13 Dec 2019 16:19:49 -0500 Received: from mail-qt1-f180.google.com ([209.85.160.180]) by mrelayeu.kundenserver.de (mreue009 [212.227.15.129]) with ESMTPSA (Nemesis) id 1MkpjD-1hzzY438Zj-00mLph; Fri, 13 Dec 2019 22:19:47 +0100 Received: by mail-qt1-f180.google.com with SMTP id 38so202656qtb.13; Fri, 13 Dec 2019 13:19:47 -0800 (PST) X-Gm-Message-State: APjAAAW0NoVylss35sFlxcdskVlkOogJY/m4KO8Xamz3TLcOUPLXB7TS WWJIVDnIrYsmI2IolfUiHHWDG9T4q7b+knC26PQ= X-Google-Smtp-Source: APXvYqzRCmxSJ5M4TsF2GHTgNgs6xrFc14QenaNUrN3AwXjC24FO2Yu4D8N4fTZTe3LQsHdWTiNakaEj9qN7BIHzOuE= X-Received: by 2002:ac8:3a27:: with SMTP id w36mr14136712qte.204.1576271986613; Fri, 13 Dec 2019 13:19:46 -0800 (PST) MIME-Version: 1.0 References: <20191213141046.1770441-1-arnd@arndb.de> <20191213141046.1770441-11-arnd@arndb.de> <20191213211311.GA12391@fieldses.org> In-Reply-To: <20191213211311.GA12391@fieldses.org> From: Arnd Bergmann Date: Fri, 13 Dec 2019 22:19:30 +0100 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v2 10/12] nfsd: use boottime for lease expiry alculation To: Bruce Fields Cc: Chuck Lever , Linux NFS Mailing List , "linux-kernel@vger.kernel.org" , y2038 Mailman List Content-Type: text/plain; charset="UTF-8" X-Provags-ID: V03:K1:JZ7nF3P96OXpKiBUNNwd0xMUJxZuz+Fh2eeyX5X+ZSw+b1gf+ci aW9Q2fPirsgOcs+7gfg8REPBUAH17cYQIsyQ5y3Xgf+WKxQr4Xpn24GeWLRa2Z7tqmMhMEG sbmlus23/ftfiF7DrjZbNugNlP0vQS7JZo4nVjUKzOxn1pF+jJIN0jf3TpcBuuXKyR1ABEr MlPfTB9KQvNr8SDU6F4Lw== X-UI-Out-Filterresults: notjunk:1;V03:K0:Avq3HQGv51I=:KEnA+tswol0qWOKxKkWmyN VeMI8rB2wkA7+Iq4bNazJ1keOZ3uqvewIMW2uMz9rBrg+U6W5R6wE2xDI+z3Mn3gg7a6kfJzp DqPQThUX/PZpe3AOHbdkBriRQ32Y5I6dzhhy2wxW4vS/fUV0VDISd0PWuyArkDldePQfC+Dkv rrh2yjn78y4Bk61lQPW1YGt6mhA5QRsCBwopzSbFtvSWkLd5QDv1fkCccC5iX4DBesRzJvQnT 2TrPm8O1b6Ji6d9CRGoBrlUVj+JAmbod9GspYrigARECxtlph44whcc4U5nU8qaWiVEFsjcNk 9f8GxJkQmbATZZ8oMV8ZCpgLsXepJxkDrVFGOsrZuQ2wBpxUHruJtFj7R3QIGJjixuAJHvvN0 lwx0nqBR8lg8a18LjF2o196l/CR9M3D+4/M9k89eqQsqJJzCSN7fiVUIQbmQYU/w3YYlZqGiz RbCDRZEs38/6tzseVc9/OEnKBRJUUw0YZFTZN3kuNAjcRdRPabB7/YaqBLuIl5vhp8As8T+t/ Qycy0FegbMuk0gKWco/kKcwuHa4ivKuYXLgAWlq6kZtgRYdlaRboh8eDFyZOML3hrcZhAdiNG F/qyFKFXgszfg7URGx0ikO5r+GUT+ztyfCkgZvmJYUwl9X3UA6/EnCoYvbkpPrw56YSU4zOay rne3ieWbg0iZHYC8rpTqGAeBAmBRnOa70RXXXUKZQTzffRGf21zTsYo7+1y4eKZIQ/ApPxq12 oUXtlf5MFhuTZ12EpiVx6kcZEvuIgCrPJ4WqYV8/QveMZv6FCnj4AsdIVgCOJaqfi0CNLCiGH 5yH+LhzblIOXvODUoXcg+anfYl9l/K2Zqul7elRPXSu/GSJ6fZUPjQJKkRt9aLMRT/Cod+6ml VpZSBdIhWCkrct46JUPw== Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Dec 13, 2019 at 10:13 PM Bruce Fields wrote: > On Fri, Dec 13, 2019 at 01:23:08PM -0500, Chuck Lever wrote: > > > On Dec 13, 2019, at 11:40 AM, Arnd Bergmann wrote: > > > On Fri, Dec 13, 2019 at 5:26 PM Chuck Lever wrote: > > >>> + > > >>> + /* nfsd4_lease is set to at most one hour */ > > >>> + if (WARN_ON_ONCE(nn->nfsd4_lease > 3600)) > > >>> + return 360 * HZ; > > >> > > >> Why is the WARN_ON_ONCE added here? Is it really necessary? > > > > > > This is to ensure the kernel doesn't change to a larger limit that > > > requires a 64-bit division on a 32-bit architecture. > > > > > > With the old code, dividing by 10 was always fast as > > > nn->nfsd4_lease was the size of an integer register. Now it > > > is 64 bit wide, and I check that truncating it to 32 bit again > > > is safe. > > > > OK. That comment should state this reason rather than just repeating > > what the code does. ;-) > > Note that __nfsd4_write_time() already limits nfsd4_lease to 3600. > > We could just use a smaller type for nfsd4_lease if that'd help. I think it's generally clearer to have only one type to store the lease time, and time64_t is the most sensible one, even if the range is a bit excessive. I've seen too many time related bugs from mixing integer types incorrectly. Arnd