Adding support for urgent requests handling

This patch set adds support in block & elevator layers for handling urgent requests.
Urgent request notification passed to underlying driver (eMMC for example) and causes interruption of low priority current request in order to execute the urgent one.
The interrupted request is inserted back to the scheduler's internal data structures.

Tatyana Brokhman (2):
block: Add support for reinsert a dispatched req
block: Add API for urgent request handling

 block/blk-core.c         |   68 ++++++++++++++++++++++++++++++++++++++++++++-
 block/blk-settings.c     |   12 ++++++++
 block/blk.h              |   11 +++++++
 block/elevator.c         |   35 +++++++++++++++++++++++
 include/linux/blkdev.h   |    6 ++++
 include/linux/elevator.h |    8 +++++
 6 files changed, 138 insertions(+), 2 deletions(-)

1.7.6
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