svn commit: r222466 - head/sbin/umount

[Rick Macklem]

> 
> Did you have to change VFS_SYNC() to pass the forced-dismount flag? I
> don't like that, but see the problem: VFS_SYNC(XXX_WAIT) should
> normally
> just try to sync everything, but return an error if this is
> impossible,
> but for an nfs server it would take too long to determine that it is
> impossible.
> 
It just checks MNTK_UNMOUNTF being set in mnt_kern_flag.