virtiofsd: Add passthrough_ll
passthrough_ll is one of the examples in the upstream fuse project
and is the main part of our daemon here. It passes through requests
from fuse to the underlying filesystem, using syscalls as directly
as possible.
From libfuse fuse-3.8.0
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Fixed up 'GPL' to 'GPLv2' as per Dan's comments and consistent
with the 'LICENSE' file in libfuse; patch sent to libfuse to fix
it upstream.
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>