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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 25057C43381 for ; Tue, 12 Mar 2019 07:01:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DB4D7214D8 for ; Tue, 12 Mar 2019 07:01:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727251AbfCLHBv (ORCPT ); Tue, 12 Mar 2019 03:01:51 -0400 Received: from mx1.redhat.com ([209.132.183.28]:51496 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726633AbfCLHBu (ORCPT ); Tue, 12 Mar 2019 03:01:50 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 58D4E30832D8; Tue, 12 Mar 2019 07:01:50 +0000 (UTC) Received: from warthog.procyon.org.uk (ovpn-121-148.rdu2.redhat.com [10.10.121.148]) by smtp.corp.redhat.com (Postfix) with ESMTP id 0F13D5DA62; Tue, 12 Mar 2019 07:01:48 +0000 (UTC) Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: References: <22096.1551878195@warthog.procyon.org.uk> <10106.1551892803@warthog.procyon.org.uk> <17155.1552056554@warthog.procyon.org.uk> <2827.1552315718@warthog.procyon.org.uk> To: Christian Kujau Cc: dhowells@redhat.com, linux-kernel@vger.kernel.org, Anna Schumaker , Steve Dickson Subject: Re: FS-Cache: Duplicate cookie detected MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <8938.1552374108.1@warthog.procyon.org.uk> Date: Tue, 12 Mar 2019 07:01:48 +0000 Message-ID: <8939.1552374108@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.44]); Tue, 12 Mar 2019 07:01:50 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Christian Kujau wrote: > My /usr/local/src mount was mounted with vers=4.2 (default), while > nfstest_cache was mounting its test-mount with vers=4.1! Apart from the > different rsize/wsize values, the version number stood out. And indeed, > when I mount my regular NFS mount /usr/local/src with vers=4.1, the > "duplicate cookie" is no longer printed. Yeah - NFS superblocks are differentiated by a whole host of parameters, including protocol version number, and caches aren't shared between superblocks because this introduces a tricky coherency problem. The issue is that NFS superblocks to the same place do not currently manage coherency (inode attributes, data) between themselves, except via the server. However, if "fsc" isn't given on the mount commandline, the superblock probably shouldn't get a server-level cookie if we can avoid it. David