From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2020322128D; Thu, 20 Nov 2025 06:59:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.95.11.211 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763621987; cv=none; b=lk1igVyIVf621uKQMY508dM9oWOAU4YSEDssNdRQrnfZnKISSgwZr9fNHdjqImML/Co1cbXKRls6UbCLI1ZHKgByOH0/D2ysp+2GSCXZy8/ze59c/PNnrHvLJlMnc5tDHrXJgK5lo2bRxHTIJBikiUd1hjXeBPA4k30kydJ/yhc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763621987; c=relaxed/simple; bh=Hvp4Y5ZUcU9tlOrdgJ6pcbhEb6PPT9n/dACxtoMXs7E=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=NVahE6jq3H9qFtNVgnZBfpBCn4STcEQhl6Ivx3MQIAdlF7pC3OC0uo9DrkhjKjDC7YkJn5p0C2OUG7iW1QVbrTF74wPb6yw27oASNJOdAbSkeX/kdXOuLdetU+63vHvu96t8xICPUp+LuZgCl9Ba7KRIO7hieNimznPnGmsl3r4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=lst.de; spf=pass smtp.mailfrom=lst.de; arc=none smtp.client-ip=213.95.11.211 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=lst.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=lst.de Received: by verein.lst.de (Postfix, from userid 2407) id C6A5668B05; Thu, 20 Nov 2025 07:59:40 +0100 (CET) Date: Thu, 20 Nov 2025 07:59:40 +0100 From: Christoph Hellwig To: Chuck Lever Cc: Christoph Hellwig , Dai Ngo , jlayton@kernel.org, neilb@ownmail.net, okorniev@redhat.com, tom@talpey.com, alex.aring@gmail.com, viro@zeniv.linux.org.uk, brauner@kernel.org, jack@suse.cz, linux-fsdevel@vger.kernel.org, linux-nfs@vger.kernel.org Subject: Re: [PATCH v4 3/3] FSD: Fix NFS server hang when there are multiple layout conflicts Message-ID: <20251120065940.GA30524@lst.de> References: <20251115191722.3739234-1-dai.ngo@oracle.com> <20251115191722.3739234-4-dai.ngo@oracle.com> <18135047-8695-4190-b7ca-b7575d9e4c6c@oracle.com> <20251119100526.GA25962@lst.de> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) On Wed, Nov 19, 2025 at 09:09:04AM -0500, Chuck Lever wrote: > On 11/19/25 5:05 AM, Christoph Hellwig wrote: > > On Mon, Nov 17, 2025 at 11:40:22AM -0800, Dai Ngo wrote: > >>> If a .fence_client callback is optional for a layout to provide, > >>> timeouts for such layout types won't trigger any fencing action. I'm not > >>> certain yet that's good behavior. > >> > >> Some layout implementation is in experimental state such as block > >> layout and should not be used in production environment. I don't > >> know what should we do for that case. Does adding a trace point to > >> warn the user sufficient? > > > > The block layout isn't really experimental, but really a broken protocol > > because there is no way to even fence a client except when there is > > a side channel mapping between the client identities for NFS and the > > storage protocol. > > Is the protocol broken, or just incomplete, assuming that other > (unspecified) protocols are necessary to be provided? I guess it depends on your definition. There is no shared client identify between NFS and the storage protocol. So you need a side channel communication protocol such as sneakernet to register the client identities on the server. And that even assumes you have a fencing method at that level, which often might not be the case.