davfs2 malfunction in Proxmox 9.1.5 environment

[ShaMAD]

davfs2 has stopped functioning in both privileged and unprivileged LXC containers with FUSE enabled, as well as on the Proxmox host itself. The issue occurs when mounting WebDAV resources (tested with a cloud storage service), where the mount point appears empty and accessing it returns "Invalid argument" errors. However, the same configuration works correctly on a standard Debian 12.1 virtual machine.

Technical Details:

• Proxmox Version: 9.1.5 (pve-manager 9.1.5/80cf92a64bef6889)
• Kernel: 6.17.9-1-pve
• davfs2 Versions:
  • Host: 1.7.1-1 (from Debian trixie repository)
  • LXC: 1.6.1-1 (from Debian bookworm repository)
• Environment:
  • LXC containers with fuse=1 feature enabled
  • WebDAV server accessible via HTTPS (verified with curl/PROPFIND)
  • Configuration includes use_locks 0 in davfs2.conf
• Symptoms:
  • Mount command completes without errors
  • Directory listing fails with "ls: reading directory '.': Invalid argument"
  • Unmount works correctly
  • Curl/PROPFIND commands to the WebDAV server succeed
  • No relevant errors in journalctl/dmesg

Steps to Reproduce:

1. Install davfs2 on Proxmox host or LXC container
2. Configure davfs2.conf with use_locks 0
3. Mount WebDAV resource: mount.davfs -o no_cache,username=user@domain https://webdav.cloud.mail.ru/ /mount/point/
4. Attempt to list directory contents

Expected Behavior:
Directory should display contents as it does on a standard Debian 12.1 VM.

Actual Behavior:
Mount appears successful but directory access fails with "Invalid argument" error.

Additional Notes:

• The issue appears specific to Proxmox environment (both host and containers)
• Standard Debian VMs on the same Proxmox host work correctly
• FUSE is properly enabled in LXC configuration (features: fuse=1)
• No firewall blocks detected (WebDAV accessible via curl)

Please investigate this regression in davfs2 functionality within the Proxmox environment. The issue affects both container and host-level operations, suggesting a potential compatibility problem between davfs2/FUSE and Proxmox kernel configurations.

 

[jka7]

Hey,
I had the same error using davfs2 1.7.1.
Removing the package and installing version 1.7.2-1 fixed it for me.

apt remove davfs2
apt install davfs2="1.7.2-1"

 

[gfngfn256]

This seems to be a bug with Linux kernel >=6.16 - as documented here.
As indicated above it has been patched/fixed in davfs2 1.7.2-1.

It would seem that for older versions, it can be "fixed" with:

set buf_size to 64 in
/etc/davfs2/davfs2.conf