davfs2 often freezes any program that uses it

[R. Diez]

I am running Kubuntu 14.04.3 and I am connecting to a Strato Hidrive WebDAV share with davfs2. In fact, I am still looking for some small, free cloud drive for some private files, I do not care which one. For privacy reasons, I am mounting an encrypted EncFS on top of the cloud drive. My current test drive has only a few files, all well below 1 MiB. The Internet connection is quite OK at 16 Mbps.

I found that applications that use the davfs2 mount randomly freeze. Example applications are Emacs, LibreOffice Writer and KDE's Dolphin. There is no way to unfreeze them, and trying to unmount WebDAV share fails, no matter what unmount flags (like lazy umount) I try.

My freeze symptoms are also described on the following pages:

  https://serverfault.com/questions/590696/forcefully-unmounting-filesystem

  https://serverfault.com/questions/597733/a-mount-of-box-com-as-davfs2-hangs-and-does-not-become-unstuck

  https://bugzilla.redhat.com/show_bug.cgi?id=895118

Is there a way to unfreeze the davfs2 mount, even if it means losing WebDAV files? I do not want to restart the PC every time this happens.

Kubuntu 14.04.3 comes with davfs2 1.4.7, but I noticed that more recent Ubuntu distributions have the newer version 1.5.2.

The upstream web site is at https://savannah.nongnu.org/projects/davfs2 and has no e-mail address or mailing list. There is a bug report system, but I am investigating and have yet no specific bug to report. There is also a support ticket system, but tickets stay there years marked as "in progress". I could not see anything about freezing, even though it seems a rather common problem.

I managed to find a working e-mail address for the lone upstream maintainer, Werner Baumann, and he did answer. He explained that software tends to think that disk accesses cost nothing and very easily overload the WebDAV server. File managers like Dolphin are especially prone to this. The trouble is, a frozen Dolphin normally means that your entire KDE desktop freezes.

However, I am seeing the freezing problem with Emacs opening a single text file. Waiting for half an hour does not help. Emacs becomes then the only frozen software on the computer, everything else still runs fine. When that happens, as soon as other software touches the WebDAV share, it freezes too.

davfs2 has some kind of cache. I tried creating a ~/.davfs2/davfs2.conf with these settings, but they did not help either:

  use_locks 0
  gui_optimize 1

The way it is now, davfs2 is unusable on Ubuntu, and actually damaging for the whole desktop environment.

I am considering compiling the latest 1.5.2, but I do not want to overwrite the system's default version. However, the README says that 'mount.davfs' will be installed with setuid root. Is there a way to install this on my home directory and let it run without root privileges? It is a FUSE thing after all. I would not want to overwrite the system's /etc/davfs2/davfs2.conf, but use other copies instead, and according to the README if you run mount.davfs it will overwrite the system config files.

At first, I thought that maybe the server is not responding quickly. There seems to be no way to adjust server timeouts in davfs2, so I could not try lowering them.

I learnt that there are alternatives like fusedav and gvfs-mount. Do they work any better?

[Armin Schindler (armin-melware)]

I can confirm the same problems on Ubuntu Server 15.10 which comes with davfs2 1.5.2.

A reboot is the only way to resolve that error. And sometimes even the reboot is not correctly finished
and a reset of the machine is needed.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Armin Schindler (armin-melware)]

After some testing with own debug output, I found the cause for the hang and I added a support request for davfs2:

https://savannah.nongnu.org/support/?109009

[David Fraser (davidf)]

Note that davfs2 1.5.4 was released with a fix for this (https://savannah.nongnu.org/forum/forum.php?forum_id=8518). There are packages in yakkety and zesty but not yet xenial

[David Fraser (davidf)]

(Of course, there may be other freezes other than the one that Armin reported that was fixed)

[Mantas Kriaučiūnas (mantas)]

I've backported official davfs2 1.5.4-2 packages from Ubuntu 17.10 to 16.04 (Xenial), you can add official Ubuntu-derivative Baltix-Linux PPA - ppa:baltix-members/ppa and update, see
https://launchpad.net/~baltix-members/+archive/

[Erik (bovedder)]

I have same issue with ubuntu 18.04, I use davfs2 to connect to my OneDrive box, I use following mounting instruction:

sudo mount -t davfs -o uid=xxx, username=xxx https://one/drive/Documents/ /home/mounting_dir/

I was working well until this weekend. I read a thread on redhat:

https://bugzilla.redhat.com/show_bug.cgi?id=895118

And I can confirm that enable gnome extensions are causing the freeze of my machine. By now disable extensions and re-logging with this setup I'm able to mount my OneDrive.

[Woodrow Shen (woodrow-shen)]

Does someone try mounting via nautilus on focal?

[Woodrow Shen (woodrow-shen)]

From my initial test, I don't hit this problem by opening nautilus on focal, and I can remotely navigate directories mounted by davfs.