any reason for CONFIG_FUSE_FS=y

[Bernd Schubert]

Hi Dimitri,

On 8/9/22 15:54, Dimitri John Ledkov wrote:
> Hi,
> 
> On Tue, 9 Aug 2022 at 14:22, Bernd Schubert <bs_lists at aakef.fastmail.fm> wrote:
>>
>> Hello,
>>
>> I would like to ask if there is a good reason Ubuntu builds fuse as
>> statically into the kernel instead of using a module?
>>
>> Reason I'm asking is that we are currently working on a couple of fuse
>> improvements and
>>
>> a) A static module makes development a bit harder, I cannot take any
>> quickly installed ubuntu system and just load an updated module, but
>> always need to install a non custom kernel package.
>>
>> b) Makes it impossible to provide the updated module as preview to our
>> customers, without extra work like renaming all exported symbols and
>> adding another /dev/something char device to replace /dev/fuse
>>
>> c) Makes it hard for us to support customer issues if a fuse issue
>> should come up (rare case).
>>
> 
> Historically this is due to many bugs with dynamically loaded fuse. It
> is an autoloadable module, thus userspace requesting fuse would
> autoload it. then later one has to mount /sys/fs/fuse/connections
> which is all racy. And in practice fuse is often always in use as
> well..... on my system it is common to mount things in nautilus with
> fuse; lxd/lxc uses fuse; and keybase as well. Also my windows
> partition is mounted with fuse (not sure why it's not using kernel's
> module here).
> 
> you can change ACL methods to not make /dev/fuse accesible; or change
> udev rules not not even create it; then make your loaded module
> provide /dev/fuse possibly under a different character device number.
> You can use linux-backports infrastructure to create a
> non-symbol-clashing fuse module (see how we build and vendor
> backports-iwlwifi module). Or something similar.

hmm ok, I would have added "modprobe fuse" in a initramfs script and so 
only users who manually unloaded the module would get issues?

> 
> But furthermore.... If you have an improved fuse module, can we not
> make it available as part of stock Ubuntu or Ubuntu Pro? If it is
> useful, and your customers are on Ubuntu, let's make it the best out
> of the box experience.
> 

We are in the process to upstream out changes. We got disrupted by other 
work for our main product but will continue to send new patches soon.
However, as expected getting the patches upstream takes time, which is 
replacing the module might be helpful.


Thanks,
Bernd