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From: Amir G. <ami...@gm...> - 2021-01-08 09:09:12
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> > Miklos, > > > > I would like to point out that this discussion is relevant to any low level > > fuse filesystem, but especially those that are proxying a real filesystem. > > > > I have raised this question before in the FUSE_PASSTHROUGH threads. > > There is a lot of code duplication among various low-level fuse projects and > > as we get to NFS export support and complex issues like this one, is it > > getting unlikely that all projects will handle this correctly. > > > > Do you think there is room for some more generic code in libfuse and if > > so how? Following an example implementation (assuming it gets fixed) > > and hand picking fixes to projects cannot scale for long. > > > > The challenge is that most of the generic code would be in lookup and > > maintaining the internal inode cache, but each filesystem may need > > different representations of the Inode object. > > > > I was thinking of something along the lines of an OO library that > > implements the generic lookup/inode cache for a base FuseInode class > > that implementers can inherit from. > > > > This doesn't need to be in the libfuse project at all. > > Seeing the virtiofsd already has a Rust implementation that is BSD > > licensed, maybe that can be used as a starting point? > > > > David, > > > > How hard do you think it would be to re-factor virtiofsd-rs to > > an implementation that inherits from a base passthroughfsd-rs? > > > > BTW, is virtiofsd-rs the offical virtiofsd or an experimental one? > > Which tree does Miklos' patch apply to? > > > > Anyone has other thoughts about how to reduce fragmentation in > > implementations? > > There's an fuse-backend-rs[1] project hosted on cloud-hypervisor, it is > a library to communicate with the Linux FUSE clients, which includes: > > - ABI layer, which defines all data structures shared between linux Fuse > framework and Fuse daemons. > - API layer, defines the interfaces for Fuse daemons to implement a > userspace file system. > - Transport layer, which supports both the Linux Fuse device and > virtio-fs protocol. > - VFS/pseudo_fs, an abstraction layer to support multiple file systems > by a single virtio-fs device. > - A sample passthrough file system implementation, which passes through > files from daemons to clients. > > I'm wondering if fuse-backend-rs is a proper project to work on, and > maybe virtiofsd-rs could be switched to use it as well in the future. > > Thanks, > Eryu > > [1] https://github.com/cloud-hypervisor/fuse-backend-rs Hi Eryu! This looks very interesting. Can you guys say a few words about the maturity of this project. Does it have any CI? any beta/production workloads that use it? I would be happy to contribute the open_by_handle_at() changes if I know they will get properly tested. As demonstrated in this demo fs [1], with xfs/ext4 as underlying filesystem, full NFS support can be implemented by implementing lookup in filesystem by inode only, before fuse adds support to LOOKUP_HANDLE in the protocol. Thanks, Amir. [1] https://github.com/amir73il/libfuse/commits/cachegwfs |