`Errored: Invalid Argument` when downloading to Qemu shared directory

rgri commented 2 months ago

qBittorrent & operating system versions

qBittorrent: 4.6.5 x64 Operating system: NixOS 24.11.20240809.5e0ca22 (Vicuna) Qt: 6.7.2 Libtorrent: 2.0.10.0 Boost: 1.81.0 OpenSSL: 3.0.14 zlib: 1.3.1

What is the problem?

In a qemu VM, qBittorrent will download perhaps .1-.5% of a torrent which targets a directory shared between the host and guest before stopping with Errored: Invalid Argument.

.part files as well as partially completed files and directories are written to the shared directory
being root or normal user in the guest makes no difference
being root or normal user in the host makes no difference
setting temporary files to a directory which isn't shared will work (qBittorrent can move the completed files without issue)
not a duplicate of #17938 since restarting the torrent will cause the same error
security_model of passthrough or none on the shared directory makes no difference
the error does not occur when targeting directories in the guest that are not shared
starting qBittorrent inside of the shared directory makes no difference

Steps to reproduce

On non-NixOS (I don't have a non-NixOS computer to test with)

Start a qemu VM with a flag like: -virtfs local,path=/home/USER/temp,security_model=none,mount_tag=temp
Attempt to download a torrent with the "Save at" field set to a path under /home/USER/temp

On NixOS (easiest if you do not have knowledge of qemu, and how I've tested this)

Import this module into your config and nixos-rebuild build-vm:

{ config, lib, pkgs, ... }:
let USER = "";
in {
virtualisation.vmVariant.virtualisation.sharedDirectories."temp" = {
target = "/home/${USER}/temp";
source = "/home/${USER}/temp";
};
}

Attempt to download a torrent with the "Save at" field set to a path under /home/USER/temp

Additional context

No response

Log(s) & preferences file(s)

preferences_logs.zip

rgri commented 2 months ago

I fixed this by mounting the drive with the option cache=mmap[1], which is not set on NixOS by default when creating virtual machines with nixos-rebuild build-vm. Attached is a screenshot of the working /etc/fstab line. workingfstab

Also, here is the nixos option I used to set this flag:

virtualisation.vmVariant.virtualisation.fileSystems."/home/USER/Videos/Media".options =
      [ "cache=mmap" ];

Joniator commented 2 months ago

Thank you, I've had the same issue in an Unraid VM running in the docker image on ubuntu, with the download dir set to my Unraid Share mount (9p/virtio) for quite some time, and worked around it by downloading to my os and then move it to the share.

This was the tip I needed, adding a cache=mmap to my /etc/fstab fixed it: media /mnt/media 9p [...],cache=mmap 0 0

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