cross-device copying / USB improvements

[Matthew Dillon]

:If the disk layer ack'ed the block, it should be on stable storage, 
:right?  Otherwise it isn't.  To me that would mean that we just have to 
:write out all blocks in flight (those with errors) and the ones we 
:didn't even write yet.  Of course that's only true for non-caching 
:media, but what can you do.
:
:cheers
:   simon

    Nope.  The device is virtually guaranteed to ack the block before
    it reaches stable storage, particularly if it is a flash device.

					-Matt
					Matthew Dillon 
					<dillon at backplane.com>