Re: [PATCH 2/2] NFSv4.1: Ask for no delegation on OPEN if already holding one

From: Trond Myklebust <trond.myklebust@primarydata.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: Linux NFS Mailing List <linux-nfs@vger.kernel.org>,
	"Kornievskaia, Olga" <Olga.Kornievskaia@netapp.com>
Subject: Re: [PATCH 2/2] NFSv4.1: Ask for no delegation on OPEN if already holding one
Date: Thu, 5 Feb 2015 09:49:57 -0500	[thread overview]
Message-ID: <CAHQdGtRtnTEf0UoLjLbwUAPncfEzg1W43oAZu2UyueychvJ0mQ@mail.gmail.com> (raw)
In-Reply-To: <20150205140701.GA3941@infradead.org>

On Thu, Feb 5, 2015 at 9:07 AM, Christoph Hellwig <hch@infradead.org> wrote:
> On Tue, Feb 03, 2015 at 04:59:44PM -0500, Trond Myklebust wrote:
>> If we already hold a delegation, there should be no reason for the
>> server to issue it to us again. Unfortunately, there appear to be
>> servers out there that engage in this practice. While it is often
>> harmless to do so, there is one case where this creates a problem
>> and that is when the client is in the process of returning that
>> delegation.
>> This patch uses the NFSv4.1 NFS4_SHARE_WANT_NO_DELEG flag to inform
>> the server not to return a delegation in these cases.
>
> Shouldn't this be patch 1 as it's the actual bug fix that might need
> backporting?

I'm dropping it instead. It doesn't completely close the race left
open by the lack of clarity in the protocol, and so it is
counterproductive; it will leave sloppy server vendors thinking the
problem is solved when it isn't.

-- 
Trond Myklebust
Linux NFS client maintainer, PrimaryData
trond.myklebust@primarydata.com