Return-Path: Received: from mail-it0-f68.google.com ([209.85.214.68]:33679 "EHLO mail-it0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751201AbcFAUbX (ORCPT ); Wed, 1 Jun 2016 16:31:23 -0400 Received: by mail-it0-f68.google.com with SMTP id v125so226700itc.0 for ; Wed, 01 Jun 2016 13:31:23 -0700 (PDT) MIME-Version: 1.0 Date: Wed, 1 Jun 2016 16:31:22 -0400 Message-ID: Subject: open_downgrade use From: Olga Kornievskaia To: linux-nfs Content-Type: text/plain; charset=UTF-8 Sender: linux-nfs-owner@vger.kernel.org List-ID: I'm failing to think of what can trigger an open_downgrade? I thought the following example should trigger an open downgrade: fd0 = open(foo, RDRW) -- should be open on the wire for "both" fd1 = open(foo, RDONLY) -- should be open on the wire for "read" close(fd0) -- should trigger an open_downgrade read(fd1) close(fd1) However this commit says that it's not allowed by the spec. commit cd9288ffaea4359d5cfe2b8d264911506aed26a4 Author: Trond Myklebust Date: Thu Sep 18 11:51:32 2014 -0400 NFSv4: Fix another bug in the close/open_downgrade code James Drew reports another bug whereby the NFS client is now sending an OPEN_DOWNGRADE in a situation where it should really have sent a CLOSE: the client is opening the file for O_RDWR, but then trying to do a downgrade to O_RDONLY, which is not allowed by the NFSv4 spec. Reported-by: James Drews Link: http://lkml.kernel.org/r/541AD7E5.8020409@engr.wisc.edu Fixes: aee7af356e15 (NFSv4: Fix problems with close in the presence...) Cc: stable@vger.kernel.org # 2.6.33+ Signed-off-by: Trond Myklebust If RDWR to RDONLY isn't allowed then why do we have OPEN_DOWNGRADE at all?