From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 DA7BC17E904 for ; Wed, 3 Jul 2024 15:28:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720020536; cv=none; b=rlZfQ+fdMQg/ZVGob6x91t0w37Br0DXs4bNVfCje7g8bTezcbDOQEqteqJZEdAB/TBPgBxTyHxzUrisop2Njtklki4Ur9F5Lby9zrmW0ahlmCKHBenI6lBWPUTpxypcj/uNTA151rAV6sOf+QdeiO/ls2vQyupP7bWPfLI5gPT8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720020536; c=relaxed/simple; bh=uamJg7AE2nLUeZhQd/dGJD0WXtKbpqECp8TS2b/eHYs=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=LN8vxV6eZK8gUqeki9JXoIWWaVQxHfCrwSDeDdtZ5Xf2X6jJgQ8uv5x11MSFnRIWEiVZ6C9WwFU1pESQLQ9fk9prqUR+jgn46T4UnjjIEzGMFfwadQ06zcPrkqUzLMhzaZRkRqmqeK0jZSxHm2VERKEYGJ6CjO2W4hRZZi+C9iA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=WcD587DP; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="WcD587DP" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 34312C2BD10; Wed, 3 Jul 2024 15:28:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1720020536; bh=uamJg7AE2nLUeZhQd/dGJD0WXtKbpqECp8TS2b/eHYs=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=WcD587DPqBPSVdKZY9Sb1+oi4a1Jm6tf4BcB3VAkHXfnIE1gA8gU7cg2Xlw2TfrwA IaUHD7K1hmAcgj2ScAD4GqVJpyWlhQ6cAi9XQduCPiGqTgDB5bhfukG+5kmfDhaGJ3 USy6H5PLDOCzLW1kywFwEXhKjZsCxOIt3r0LtF8zdiOffBCy362iZXfEqDkQ98mCgF 2NbUio3sog80p+/NfrU5uK3yr1FyjznOoOcI4ErvMmnZXzH4S/HqV0ki4ZCCx+vOx5 1b4+TZBt3gRtMcb0wZ3uyUxI/UMNUfA2lG93bpY7YbdfDwWU51EuhVE+tPM9HYYcNY ot6S/g0JdnayA== Date: Wed, 3 Jul 2024 11:28:55 -0400 From: Mike Snitzer To: Christoph Hellwig Cc: linux-nfs@vger.kernel.org, Jeff Layton , Chuck Lever , Anna Schumaker , Trond Myklebust , NeilBrown , snitzer@hammerspace.com Subject: Re: [PATCH v11 00/20] nfs/nfsd: add support for localio Message-ID: References: <20240702162831.91604-1-snitzer@kernel.org> Precedence: bulk X-Mailing-List: linux-nfs@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: On Wed, Jul 03, 2024 at 08:16:00AM -0700, Christoph Hellwig wrote: > I've stated looking a bit at the code, and the architectural model > confuses me more than a bit. > > A first thing that would be very helpful is an actual problem statement. > The only mention of a concrete use case is about containers, implying > that this about a client in one container/namespace with the server > or the servers in another containers/namespace. Is that the main use > case, are there others? Containers is a significant usecase, but also any client that might need to access local storage efficiently (e.g. GPU service running NFS client that needs to access NVMe on same host). > I kinda deduct from that that the client and server probably do not > have the same view and access permissions to the underlying file > systems? As this would defeat the use of NFS I suspect that is the > case, but it should probably be stated clearly somewhere. I can tighten that up in the Documentation. > Going from there I don't understand why we need multiple layers of > server bypass. The normal way to do this in NFSv4 is to use pNFS > layout. > > I.e. you add a pnfs localio layout that just does local reads > and writes for the I/O path. We'd still need a way to find a good > in-kernel way to get the file structure, but compared to the two > separate layers of bypasses in the current code it should be > significantly simpler. Using pNFS layout isn't viable because NFSv3 is very much in the mix (flexfiles layout) for Hammerspace.