fuse: use fuse3 as default.

[YellowOnion]

Describe the bug:

fuse3 has a bunch of updates that whitelist various file systems, exfat, bcachefs, etc.

nix-shell -p '(gocryptfs.override {fuse=fuse3;}).overrideAttrs (attrs: {propagatedBuildInputs = attrs.propagatedBuildInputs ++ [fuse3];})' fuse3

[nix-shell:~]$ gocryptfs ~/danie/Documents/crypt/ ~/crypt
Password: 
Decrypting master key
/run/wrappers/bin/fusermount: mounting over filesystem type 0xca451a4e is forbidden
fs.Mount failed: fusermount exited with code 256

fusermount is hardcoded here: https://github.com/hanwen/go-fuse/blob/3ab5d95a30ae25019bf030a2bab076dba61c27da/fuse/mount_linux.go#L219

but nixos packages fuse3 as fusermount3

Maybe it's time to make fuse3 the "default" as it's 4 years old, and fuse2 should explicitly provide fusermount2

Notify maintainers

@primeos

[colemickens]

+1

[primeos]

It'd be nice if someone could check what other distributions do and if there are compatibility issues. Upstream recommends the 3 suffix. E.g. https://github.com/libfuse/libfuse/blob/d709c24cbd9e1041264c551c2a4445e654eaf429/ChangeLog.rst#libfuse-300-2016-12-08:

NOTE TO PACKAGERS:

libfuse 3 is designed to be co-installable with libfuse 2. However, some files will be installed by both libfuse 2 and libfuse 3 (e.g. /etc/fuse.conf, the udev and init scripts, and the mount.fuse(8) manpage). These files should be taken from libfuse 3. The format/content is guaranteed to remain backwards compatible with libfuse 2.

We recommend to ship libfuse2 and libfuse3 in three separate packages: a libfuse-common package that contains files shared by libfuse 2+3 (taken from the libfuse3 tarball), and libfuse2 and libfuse3 packages that contain the shared library and helper programs for the respective version.

The fusermount and mount.fuse binaries have been renamed to fusermount3 and mount.fuse3 to allow co-installation of libfuse 2.x and 3.x

I quickly looked at Ubuntu 20.04 LTS:

$ fusermount --version
fusermount version: 2.9.9
# But installing fuse3 will remove fuse:
$ apt -qqqs install fuse3
Inst libfuse3-3 (3.9.0-2 Ubuntu:20.04/focal [amd64])
Remv fuse [2.9.9-3] [ntfs-3g:amd64 ]
Inst fuse3 (3.9.0-2 Ubuntu:20.04/focal [amd64])
Conf libfuse3-3 (3.9.0-2 Ubuntu:20.04/focal [amd64])
Conf fuse3 (3.9.0-2 Ubuntu:20.04/focal [amd64])

And Debian 10: Same result (considering the major versions).

Edit: Arch seems to use that suffix for fuse3 as well: https://archlinux.org/packages/extra/x86_64/fuse3/

[oxalica]

Another year passed, fuse 2.9.9, the latest release of fuse2, has been 4 years old. Also from its release note,

Note: This is a maintenance release from the 2.9 branch of libfuse. Users are encouraged to transition to the
actively developed libfuse 3.x.

Is it time for transition now?

[S-NA]

I ran into this recently for something I was working on. It would be nice to see fuse3 become the default, though from my initial impression, a lot of code bases do not work with simply swapping out fuse2 for fuse3. In the meantime, people can work around the forbidden mount issue by creating a tmpfs mount point.

[YellowOnion]

I'm far more familiar with nix that I was when I originally opened this, this can probably be worked around by providing a fuse2 -> fuse wrapper (and a fuse3 -> fuse wrapper too) around specific packages that need fuse2, I think it makes more sense to default to the newer version and fix old packages, than stay on fuse2 indefinitely. One of the benefits of nix is being able to do this over expecting all software to work with the fusemount provided by the OS.

@primeos what are your thoughts?