block: Expose kblock_schedule_delayed_work()

This function is exported in blk-core.c to be used in other modules
but it's definition in h file is missing.

Signed-off-by: Tatyana Brokhman <tlinder@codeaurora.org>
block: Adding ROW scheduling algorithm

This patch adds the implementation of a new scheduling algorithm - ROW.
The policy of this algorithm is to prioritize READ requests over WRITE
as much as possible without starving the WRITE requests.
The requests are kept in queues according to their priority. The dispatch
is done in a Round Robin manner with a different slice for each queue.
READ request queues get bigger dispatch quantum than the write requests.

Signed-off-by: Tatyana Brokhman <tlinder@xxxxxxxxxxxxxx>
---
v4:
  - Fix bug in idling mechanism:
    -- Fix the delay passed to scedule_delayed_work
    -- Change the idle delay and idling-trigger frequency to be HZ dependent
  - Destroy idle_workqueue on queue exit
  - Update the documentation

v3:
  - Fix bug in forced dispatch: Don't idle if forced dispatch

v2:
  No changes. Resend.

v1: Initial version
block:minor edits to completely enable row i/o scheduling algorithm

Signed-off-by: sarcastillo <sar.castillo@gmail.com>