VOP_GETATTR() can sleep when accessing a file over NFS, so use FREF()/FRELE() in lseek() so our struct file doesn't disappear in the mean time.
VOP_GETATTR() can sleep when accessing a file over NFS, so use
FREF()/FRELE() in lseek() so our struct file doesn't disappear in the
mean time.

Incorporating suggestions from tedu@ and guenther@; ok guenther@

orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars