new DMA API conversion for nvme-pci v3

[Christoph Hellwig]

Hi all,

this series converts the nvme-pci driver to the new IOVA-based DMA API
for the data path.

Chances since v2:
 - fix handling of sgl_threshold=0

Chances since v1:
 - minor cleanups to the block dma mapping helpers
 - fix the metadata SGL supported check for bisectability
 - fix SGL threshold check
 - fix/simplify metadata SGL force checks

Diffstat:
 block/bio-integrity.c      |    3 
 block/bio.c                |   20 -
 block/blk-mq-dma.c         |  161 +++++++++++
 drivers/nvme/host/pci.c    |  615 +++++++++++++++++++++++++--------------------
 include/linux/blk-mq-dma.h |   63 ++++
 include/linux/blk_types.h  |    2 
 6 files changed, 597 insertions(+), 267 deletions(-)