fs — virtio-fs

github.com/go-virtio/fs is a pure-Go virtio-fs (FUSE-over-virtio) guest driver for the standard PCI-bound device (VID 0x1AF4, DID 0x105A — device type 26). It implements the modern-transport (Virtio 1.0+) init sequence, the request virtqueue, and the FUSE-over-virtio wire framing. CGO=0, no architecture-specific assembly, 100% statement test coverage.

Scope

Like blk, this package owns device bring-up, a request virtqueue, and the on-the-wire request format. For virtio-fs the request is a FUSE message carried as a descriptor chain (Virtio 1.2 §5.11.6):

readable descriptors : [ struct fuse_in_header  | op-specific in-args  ]
writable descriptors : [ struct fuse_out_header | op-specific out-args ]

The driver exposes a read-write mount closure, each op cited from Linux include/uapi/linux/fuse.h.

Side	Ops
Read	Init, Lookup, GetAttr, Open, Read, Release, Forget, Destroy
Write	OpenRW, Write, Create, Mkdir, Mknod, Symlink, Link, SetAttr, Unlink, Rmdir, Rename, Fsync, Flush

SetAttr covers truncate (FattrSize), chmod (FattrMode), chown (FattrUID/FattrGID) and utimes (FattrAtime/FattrMtime) via the fuse_setattr_in.valid mask. FUSE_WRITE is the only op whose request is a three-region descriptor chain (readable header + data, writable reply).

Validated against a real virtiofsd

v0.2.1 fixes a fuse_attr struct-size bug found by real-virtiofsd validation — the kind of bug a fake-device unit test cannot catch.

License

BSD-3-Clause.