not set, unlock the vnode before calling the device's close routine and
relock it after it returns. tty close routines will sleep waiting for
buffers to drain, which won't happen often times as the other side needs
to grab the vnode lock first.
Make all unmount routines lock the device vnode before calling VOP_CLOSE().
call with F_FSCTL set and F_SETFL calls generate calls to a new
fileop fo_fcntl. Add genfs_fcntl() and soo_fcntl() which return 0
for F_SETFL and EOPNOTSUPP otherwise. Have all leaf filesystems
use genfs_fcntl().
Reviewed by: thorpej
Tested by: wrstuden
Update coda to new struct lock in struct vnode.
make fdescfs, kernfs, portalfs, and procfs actually lock their vnodes.
It's not that hard.
Make unionfs set v_vnlock = NULL so any overlayed fs will call its
VOP_LOCK.
client programs are allowed to finish up (coda_call is
forced to complete) and release their locks. Thus there
is a reasonable chance that the vflush implicit in the
unmount will not get hung on held locks.
