From: Ian Kent <raven@themaw.net>

Remove BKL from autofs4 module and add spinlock to serialise access to the
automount daemon communication waitq.

Locking requirements are different in 2.6 and so I'm seeking comments and
suggestions on this.  I have taken a rather heavy handed approach to this in
the patch.  For example, the VFS operations that directly change the
filesystem, such as autofs4_mkdir etc, hold the inode semaphore on entry so
the BKL has been removed.  I can't see why two locking mechanisms are needed.
 Rather than add locking all over the place, I'm looking for justification
it's needed, as I don't see it myself.