The in-kernel NFS server has some idiosyncracies. For example, it never
calls VOP_OPEN. So there are code paths within fusefs that cannot be
hit through regular userspace syscalls alone. To exercise these code
paths, add tests that create VNET jails and run nfsd within the jails,
then mount the exported fuse file systems and access them using the
regular NFS client.
Also, add a regression test for bug 283448: a use-after-free accessible
only via nfsd. Add the test, but don't yet fix the bug.
PR: 283448
Sponsored by: ConnectWise
Also,
fusefs: don't exclusively lock during VFSOP_FHTOVP
I think the only reason why this code used LK_EXCLUSIVE was because it
was copied from ext2.
MFC after: 2 weeks
Sponsored by: ConnectWise