scsi-mq: make the scsi-mq work.

Hi nab:
Test http://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending.git/scsi-mq, it can't work for my machine(using ahci driver).
From this branch, i know it support ahci with scsi-mq/block-mq.So i modify some place to make it can work.
For this patchset, i only test read/write and on oops/hung_task occur.

Jianpeng Ma (6):
block: support blk-mq on blk_run_queue/blk_run_queue_async.
scsi-mq: add operations about device_busy/target_busy/host_busy in

     scsi_mq_queue_rq().
  scsi-mq: Don't set QUEUE_FLAG_NONROT in scsi_mq_alloc_queue().
  scsi-mq: init sg in scsi_init_io.
  scsi-mq: fix 'BUG_ON(count > sdb->table.nents)' in
    scsi_init_sgtable().
  scsi-mq: Pre-allocation of sg tables base on
    min(host->hostt->sg_tablesize, SCSI_MQ_MAX_SG_SEGMENTS).

 block/blk-core.c        |   21 ++++++++++++++-------
 drivers/scsi/scsi-mq.c  |   33 ++++++++++++++++++++++++++++-----
 drivers/scsi/scsi_lib.c |    4 +++-
 3 files changed, 45 insertions(+), 13 deletions(-)

1.7.10.4