I/O Scheduler Framework

[Matthew Dillon]

    I'm slapping this part of the IRC conversation into email so we
    don't lose it:

Step #1:  Replace all calls to dev_dstrategy() with calls to io_schedule()
	  ins tead.  And write an io_schedule() function which then
	  (for now) just calls dev_dstrategy().

Step #2:  Implement the process-based policy structure and system calls.

Step #3:  Associate policy information with each BIO

Step #4:  Build the dynamic instancing for the (policies x cdev_t) matrix.

Step #5:  Start implementing the actual I/O scheduler algorithm

						-Matt