virtiofs File::metadata support

[m-mueller678]

Currently, getting the metadata for a handle to a virtiofs file fails with an InvalidInput error:

fn main(){
    let file = File::open("/root/example.csv").unwrap();
    file.metadata().unwrap();
}

This, however, works fine.

fs::metadata("/root/example.csv")

I did not test other filesystems, they may or may not have the same issue

[n0toose]

To the best of my knowledge, I discovered yesterday that this issue also affects Uhyve.

[m-mueller678]

I started work on this yesterday. It seems straight forward, though I am not super confident about my understanding of virtiofs.

[n0toose]

though I am not super confident about my understanding of virtiofs

Is anyone really confident about their understanding of virtio-fs? Been having some troubles myself as of the past two days - mind if I ask you for the precise QEMU command that you used?

I'm facing another issue and I'm currently trying to reproduce it - I'd be interested in reproducing this issue locally as well, and your attempt seems to be fairing way better than mine.

[m-mueller678]

This is what I am using right now to run my application:

virtiofsd --shared-dir=./test_dir --socket-path=/tmp/vhostqemu &

qemu-system-x86_64\
  -cpu host\
  -enable-kvm\
  -display none\
  -smp 1\
  -m 8G\
  -serial stdio\
  -kernel ~/Downloads/hermit-loader-x86_64\
  -initrd target/x86_64-unknown-hermit/debug/hermit-rs-template\
  -chardev socket,id=char0,path=/tmp/vhostqemu\
  -device vhost-user-fs-pci,queue-size=1024,chardev=char0,tag=root\
  -object memory-backend-file,id=mem,size=8G,mem-path=/dev/shm,share=on\
  -numa node,memdev=mem