Return-Path: Received: from fieldses.org ([173.255.197.46]:54732 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752963AbdJTTTf (ORCPT ); Fri, 20 Oct 2017 15:19:35 -0400 Date: Fri, 20 Oct 2017 15:19:35 -0400 From: "J. Bruce Fields" To: Arnd Bergmann Cc: Jeff Layton , y2038 Mailman List , Deepa Dinamani , Linux FS-devel Mailing List , Trond Myklebust , NeilBrown , Kinglong Mee , linux-nfs@vger.kernel.org, Linux Kernel Mailing List Subject: Re: [PATCH] nfds: avoid gettimeofday for nfssvc_boot time Message-ID: <20171020191935.GE15211@fieldses.org> References: <20171019100435.1170955-1-arnd@arndb.de> <1508410486.4912.11.camel@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: Sender: linux-nfs-owner@vger.kernel.org List-ID: On Thu, Oct 19, 2017 at 01:04:35PM +0200, Arnd Bergmann wrote: > On Thu, Oct 19, 2017 at 12:54 PM, Jeff Layton wrote: > > > > I wonder if we'd be better off just using nfssvc_boot.tv_sec as the > > verifier? I don't see us ever calling that ktime_get_real_ts64 more than > > once per second for this purpose, and that would eliminate wraparound. > > That said, wraparound is not a huge concern here anyway, so this is > > certainly fine for now: It might reduce the chances of a collision if someone is doing extreme boot-time optimization, or if time goes backwards for some reason? > I now have the feeling that we had previously had the same discussion > when someone else submitted a similar patch that ended up never getting > merged. I might also be confusing this with a different subsystem that > had the same requirement. > > If we want this to be as unique as possible and also never (within > a few hundred years) wrap, we could call ktime_get_real_ns(), which > returns a 64-bit nanoseconds number. Anyway, no objection to doing this differently if someone wants, but I'll just take this patch for now. Thanks.--b. > > > Reviewed-by: Jeff Layton > > Thanks. > > Arnd