seqdiag {
  app;
  fuse [label="bazil.org/fuse"];
  fusermount;
  kernel;
  mounts;

  app;
  fuse [label="bazil.org/fuse"];
  fusermount;
  kernel;
  mounts;

  app -> fuse [label="Mount"];
  fuse -> fusermount [label="spawn, pass socketpair fd"];
  fusermount -> kernel [label="open /dev/fuse"];
  fusermount -> kernel [label="mount(2)"];
  kernel ->> mounts [label="mount is visible"];
  fusermount <-- kernel [label="mount(2) returns"];
  fuse <<-- fusermount [diagonal, label="exit, receive /dev/fuse fd", leftnote="on Linux, successful exit here\nmeans the mount has happened,\nthough InitRequest might not have yet"];
  app <-- fuse [label="Mount returns\nConn.Ready is already closed"];

  app -> fuse [label="fs.Serve"];
  fuse => kernel [label="read /dev/fuse fd", note="starts with InitRequest"];
  fuse -> app [label="Init"];
  fuse <-- app [color=red];
  fuse -> kernel [label="write /dev/fuse fd", color=red];
  kernel -> kernel [label="set connection\nstate to error", color=red];
  fuse <-- kernel;
  ... conn.MountError == nil, so it is still mounted ...
  ... call conn.Close to clean up ...
}