[pve-devel] [PATCH cluster/guest-common/docs/qemu-server/manager v6 0/11] virtiofs

Fabian Grünbichler f.gruenbichler at proxmox.com
Thu Oct 5 10:57:11 CEST 2023

On August 9, 2023 10:37 am, Markus Frank wrote:
> qemu-server patches require pve-guest-common and pve-cluster patches
> pve-manager patches require the pve-doc patch
> I did not get virtiofsd to run with run_command without creating zombie
> processes after stutdown.
> So I replaced run_command with exec for now. 
> Maybe someone can find out why this happens.

some high-level remarks:
- in general, seems to work as expected within the limitations of the
  current virtiofsd
- log messages by virtiofsd after the initial startup are lost, adding
  `--syslog` or otherwise improving the process startup to capture them
  would be good
- I am not sure whether we want to expose this on the GUI just yet
- checking earlier when doing a snapshot with RAM might be sensible
  (since virtiofsd state is not migrateable, it's also not
  snapshot-saveable and aborts pretty early on, but a nicer error
  message up front would be even better)[1]
- maybe default to ACLs off, or improve detection of support, since
  having them on but no support means no mounting possible (haven't
  tested whether the same applies to XATTRs as well)
- currently virtiofsd crashing means no recovery until VM is fully
  stopped and restarted [2]
- virtiofsd not responding for whatever reason means NFS-like hanging
  access in the VM (this should be noted somewhere)
- virtiofs shares don't seem to work on older Linux VMs with memory
  hotplug enabled (it might be good to have some sort of
  supported/tested-with matrix somewhere so that users don't have to try
  known-to-not-work combinations..)
- bwlimit support once upstream has it would be nice[3]
- reboots seem broken (accessing the mount after the reboot hangs), but
  that might be fixed with a newer upstream version[4] that I'll prepare
  in the meantime :)

noting the build-order/interdependencies would be nice ;)

some more smaller nits noted in individual patches

1: https://gitlab.com/virtio-fs/virtiofsd/-/issues/81
2: https://gitlab.com/virtio-fs/virtiofsd/-/issues/62
3: https://gitlab.com/virtio-fs/virtiofsd/-/merge_requests/147
4: https://gitlab.com/virtio-fs/virtiofsd/-/commit/ee50078626536b8e25389f01e7e4be43897418c9

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