GO-FUSE

native bindings for the FUSE kernel module.

Highlights

• High speed: as fast as libfuse using the gc compiler for single threaded loads.

• Supports in-process mounting of different FileSystems onto subdirectories of the FUSE mount.

• Supports 3 interfaces for writing filesystems:

  • PathFileSystem: define filesystems in terms path names.
  • NodeFileSystem: define filesystems in terms of inodes.
  • RawFileSystem: define filesystems in terms of FUSE's raw wire protocol.

• Both NodeFileSystem and PathFileSystem support manipulation of true hardlinks.

• Includes two fleshed out examples, zipfs and unionfs.

Examples

• example/hello/main.go contains a 60-line "hello world" filesystem

• zipfs/zipfs.go contains a small and simple read-only filesystem for zip and tar files. The corresponding command is in example/zipfs/ For example,

  mkdir /tmp/mountpoint
  example/zipfs/zipfs /tmp/mountpoint file.zip &
  ls /tmp/mountpoint
  fusermount -u /tmp/mountpoint

• zipfs/multizipfs.go shows how to use in-process mounts to combine multiple Go-FUSE filesystems into a larger filesystem.

• fuse/loopback.go mounts another piece of the filesystem. Functionally, it is similar to a symlink. A binary to run is in example/loopback/ . For example

  mkdir /tmp/mountpoint
  example/loopback/loopback -debug /tmp/mountpoint /some/other/directory &
  ls /tmp/mountpoint
  fusermount -u /tmp/mountpoint

• unionfs/unionfs.go: implements a union mount using 1 R/W branch, and multiple R/O branches.

  mkdir -p  /tmp/mountpoint /tmp/writable
  example/unionfs/unionfs /tmp/mountpoint /tmp/writable /usr &
  ls /tmp/mountpoint
  ls -l /tmp/mountpoint/bin/vi
  rm /tmp/mountpoint/bin/vi
  ls -l /tmp/mountpoint/bin/vi
  cat /tmp/writable/DELETION/*

• union/autounionfs.go: creates UnionFs mounts automatically based on existence of READONLY symlinks.

Tested on:

• x86 32bits (Fedora 14).
• x86 64bits (Ubuntu Lucid).

Benchmarks

We use threaded stats over a read-only filesystem for benchmarking. Automated code is under benchmark/ directory. A simple C version of the same FS gives a FUSE baseline

Data points (Go-FUSE version May 2012), 1000 files, high level interface, all kernel caching turned off, median stat time:

platform libfuse Go-FUSE difference (%)

Lenovo T60/Fedora16 (1cpu) 349us 355us 2% slower Lenovo T400/Lucid (1cpu) 138us 140us 5% slower Dell T3500/Lucid (1cpu) 72us 76us 5% slower

On T60, for each file we have

• Client side latency is 360us
• 106us of this is server side latency (4.5x lookup 23us, 1x getattr 4us)
• 16.5us is due to latency measurements.
• 3us is due to garbage collection.

macOS Support

go-fuse works somewhat on OSX. Known limitations:

• All of the limitations of OSXFUSE, including lack of support for NOTIFY.

• OSX issues STATFS calls continuously (leading to performance concerns).

• OSX has trouble with concurrent reads from the FUSE device, leading to performance concerns.

• Tests are expected to pass; report any failure as a bug!

Credits

• Inspired by Taru Karttunen's package, https://bitbucket.org/taruti/go-extra.

• Originally based on Ivan Krasin's https://github.com/krasin/go-fuse-zip

Bugs

Yes, probably. Report them through https://github.com/hanwen/go-fuse/issues

Disclaimer

This is not an official Google product.

Known Problems

Grep source code for TODO. Major topics:

• Missing support for network FS file locking: FUSE_GETLK, FUSE_SETLK, FUSE_SETLKW

• Missing support for FUSE_INTERRUPT, CUSE, BMAP, IOCTL

• In the path API, renames are racy; See also:

  http://sourceforge.net/mailarchive/message.php?msg_id=27550667

  Don't use the path API if you care about correctness.

License

Like Go, this library is distributed under the new BSD license. See accompanying LICENSE file.