On Mon Feb 23, 2026 at 4:40 PM CET, Markus Frank wrote:
> There are two migration methods with virtiofsd.
>
> Virtiofsd in the 'find-paths' migration mode, tries to find the path
> inside of the shared directory for every filesystem object that must be
> transferred to the destination.
> Add two extra parameters that verify file handles and confirm paths.
>
> In the 'file-handles' migration mode every filesystem object is
> converted to a file handle. This migration mode requires the
> DAC_READ_SEARCH capability.
>
> Add a parameter so that migration does not abort if an error occurs.
> Aborting on error would result in a stopped VM on the destination node.
>
> Signed-off-by: Markus Frank <[email protected]>
> ---
> v2:
> * fixed broken file-handles migration method by adding
> '--modcaps=+dac_read_search' to the virtiofsd command as stated in the
> virtiofsd documentation
>
> src/PVE/QemuMigrate/Helpers.pm | 14 +++++++++++---
> src/PVE/QemuServer/Virtiofs.pm | 18 ++++++++++++++++++
> 2 files changed, 29 insertions(+), 3 deletions(-)
>
> diff --git a/src/PVE/QemuMigrate/Helpers.pm b/src/PVE/QemuMigrate/Helpers.pm
> index 466517da..9b577704 100644
> --- a/src/PVE/QemuMigrate/Helpers.pm
> +++ b/src/PVE/QemuMigrate/Helpers.pm
> @@ -21,7 +21,6 @@ sub check_non_migratable_resources {
> if ($state) {
> push @blockers, "amd-sev" if $conf->{"amd-sev"};
> push @blockers, "intel-tdx" if $conf->{"intel-tdx"};
> - push @blockers, "virtiofs" if
> PVE::QemuServer::Virtiofs::virtiofs_enabled($conf);
> }
>
> if (scalar(@blockers) && !$noerr) {
> @@ -100,8 +99,17 @@ sub check_local_resources {
> }
> if ($k =~ m/^virtiofs/) {
> my $entry = parse_property_string('pve-qm-virtiofs',
> $conf->{$k});
> - $add_missing_mapping->('dir', $k, $entry->{dirid});
> - $mapped_res->{$k} = { name => $entry->{dirid} };
> + if (my $dirid = $entry->{dirid}) {
Seems like the if (...) is unnecessary here as dirfd is a default key
and not optional?
> + $add_missing_mapping->('dir', $k, $dirid);
> + my $mapped_device = { name => $dirid };
> + $mapped_res->{$k} = $mapped_device;
> +
> + if ($dir_map->{ids}->{$dirid}->{'live-migration-method'}) {
> + $mapped_device->{'live-migration'} = 1;
> + # don't add mapped device with live migration as blocker
> + next;
> + }
> + }
> }
> # sockets are safe: they will recreated be on the target side
> post-migrate
> next if $k =~ m/^serial/ && ($conf->{$k} eq 'socket');
> diff --git a/src/PVE/QemuServer/Virtiofs.pm b/src/PVE/QemuServer/Virtiofs.pm
> index db4b9c78..1a3db50b 100644
> --- a/src/PVE/QemuServer/Virtiofs.pm
> +++ b/src/PVE/QemuServer/Virtiofs.pm
> @@ -177,6 +177,9 @@ sub start_virtiofsd {
>
> my $dir_cfg =
> PVE::Mapping::Dir::find_on_current_node($virtiofs->{dirid});
>
> + my $dirid = $virtiofs->{dirid};
> + my $dir_properties = PVE::Mapping::Dir::config()->{ids}->{$dirid};
> +
> my $virtiofsd_bin = '/usr/libexec/virtiofsd';
> if (!-f $virtiofsd_bin) {
> die "virtiofsd is not installed. To use virtio-fs, install virtiofsd
> via apt.\n";
> @@ -201,6 +204,21 @@ sub start_virtiofsd {
> push @$cmd, '--readonly' if $virtiofs->{readonly};
> push @$cmd, '--cache=' . $virtiofs->{cache} if
> $virtiofs->{cache};
> push @$cmd, '--inode-file-handles=prefer' if $prefer_inode_fh;
> +
> + if (my $method = $dir_properties->{'live-migration-method'}) {
> + # migration-on-error=abort would result in a stopped VM on
> the target node
> + push @$cmd, '--migration-on-error=guest-error';
> + if ($method eq 'find-paths') {
> + push @$cmd, '--migration-mode=find-paths';
> + push @$cmd, '--migration-verify-handles';
> + push @$cmd, '--migration-confirm-paths';
> + }
> + if ($method eq 'file-handles') {
nit: Since $method can only be one value, an elsif would be more
readable here
> + push @$cmd, '--migration-mode=file-handles';
> + push @$cmd, '--modcaps=+dac_read_search';
> + }
> + }
> +
> push @$cmd, '--syslog';
> exec(@$cmd);
> } elsif (!defined($pid2)) {
