FUSE-MT

Documentation

This code is a wrapper on top of the Rust FUSE crate with the following additions:

• Dispatch system calls on multiple threads, so that e.g. I/O doesn't block directory listing.
• Translate inodes into paths, to simplify filesystem implementation.

The fuser crate provides a minimal, low-level access to the FUSE kernel API, whereas this crate is more high-level, like the FUSE C API.

It includes a sample filesystem that uses the crate to pass all system calls through to another filesystem at any arbitrary path.

This is a work-in-progress. Bug reports, pull requests, and other feedback are welcome!

Some random notes on the implementation:

• The trait that filesystems will implement is called FilesystemMT, and instead of the FUSE crate's convention of having methods return void and including a "reply" parameter, the methods return their values. This feels more idiomatic to me. They also take &Path arguments instead of inode numbers.
• Currently, only the following calls are dispatched to other threads:
  • read
  • write
  • flush
  • fsync
• Other calls run synchronously on the main thread because either it is expected that they will complete quickly and/or they require mutating internal state of the InodeTranslator and I want to avoid needing locking in there.
• The inode/path translation is always done on the main thread.
• It might be a good idea to limit the number of concurrent read and write operations in flight. I'm not sure yet how many outstanding read/write requests FUSE will issue though, so it might be a non-issue.