BUF/BIO patch warning - committed

[Matthew Dillon]

    The BUF/BIO patch is being committed to HEAD.  I have synchronized
    the preview tag to just before the commit.

    UFS should be solid but there might be issues with other filesystems
    that will have to be worked out as the bugs are reported.  I will
    continue to test subsystems.

    There is a known issue with umounting an msdosfs filesystem which can
    be worked around by 'sync'ing it first.  I intend to reproduce and fix
    that today, after the commit.

    I must again warn people that HEAD should be considered highly 
    experimental now and probably should not be used on production systems.
    At the same time, it needs as much testing as it can :-)

    There is literally a ton of stuff that will be going into HEAD after
    this.

 					-Matt