161e9a9736
The advlock VOP takes the vnode unlocked, which makes the normal bypass function racy. Same as null_pgcache_read(), nullfs implementation needs to take interlock and reference lower vnode under it. Reported and tested by: pho Reviewed by: markj Sponsored by: The FreeBSD Foundation MFC after: 1 week Differential revision: https://reviews.freebsd.org/D31310