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.
