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Date: Wed, 19 Nov 2025 11:05:26 +0100
From: Christoph Hellwig <hch@lst.de>
To: Dai Ngo <dai.ngo@oracle.com>
Cc: Chuck Lever <chuck.lever@oracle.com>, jlayton@kernel.org,
	neilb@ownmail.net, okorniev@redhat.com, tom@talpey.com, hch@lst.de,
	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: <20251119100526.GA25962@lst.de>
References: <20251115191722.3739234-1-dai.ngo@oracle.com> <20251115191722.3739234-4-dai.ngo@oracle.com> <d7888dd6-c238-45e0-94c0-ac82fb90d6b6@oracle.com> <18135047-8695-4190-b7ca-b7575d9e4c6c@oracle.com>
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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.

I'd be all in favour of deprecating the support ASAP and then removing
it aggressively.