[RFC PATCH 0/7] evacuate struct page from the block layer

[Dan Williams <dan.j.williams@intel.com>]

Avoid the impending disaster of requiring struct page coverage for what
is expected to be ever increasing capacities of persistent memory.  In
conversations with Rik van Riel, Mel Gorman, and Jens Axboe at the
recently concluded Linux Storage Summit it became clear that struct page
is not required in many places, it was simply convenient to re-use.

Introduce helpers and infrastructure to remove struct page usage where
it is not necessary.  One use case for these changes is to implement a
write-back-cache in persistent memory for software-RAID.  Another use
case for the scatterlist changes is RDMA to a pfn-range.

This compiles and boots, but 0day-kbuild-robot coverage is needed before
this set exits "RFC".  Obviously, the coccinelle script needs to be
re-run on the block updates for kernel.next.  As is, this only includes
the resulting auto-generated-patch against 4.0-rc3.

---

Dan Williams (6):
      block: add helpers for accessing a bio_vec page
      block: convert bio_vec.bv_page to bv_pfn
      dma-mapping: allow archs to optionally specify a ->map_pfn() operation
      scatterlist: use sg_phys()
      x86: support dma_map_pfn()
      block: base support for pfn i/o

Matthew Wilcox (1):
      scatterlist: support "page-less" (__pfn_t only) entries


 arch/Kconfig                                 |    3 +
 arch/arm/mm/dma-mapping.c                    |    2 -
 arch/microblaze/kernel/dma.c                 |    2 -
 arch/powerpc/sysdev/axonram.c                |    2 -
 arch/x86/Kconfig                             |   12 +++
 arch/x86/kernel/amd_gart_64.c                |   22 ++++--
 arch/x86/kernel/pci-nommu.c                  |   22 ++++--
 arch/x86/kernel/pci-swiotlb.c                |    4 +
 arch/x86/pci/sta2x11-fixup.c                 |    4 +
 arch/x86/xen/pci-swiotlb-xen.c               |    4 +
 block/bio-integrity.c                        |    8 +-
 block/bio.c                                  |   83 +++++++++++++++------
 block/blk-core.c                             |    9 ++
 block/blk-integrity.c                        |    7 +-
 block/blk-lib.c                              |    2 -
 block/blk-merge.c                            |   15 ++--
 block/bounce.c                               |   26 +++----
 drivers/block/aoe/aoecmd.c                   |    8 +-
 drivers/block/brd.c                          |    2 -
 drivers/block/drbd/drbd_bitmap.c             |    5 +
 drivers/block/drbd/drbd_main.c               |    4 +
 drivers/block/drbd/drbd_receiver.c           |    4 +
 drivers/block/drbd/drbd_worker.c             |    3 +
 drivers/block/floppy.c                       |    6 +-
 drivers/block/loop.c                         |    8 +-
 drivers/block/nbd.c                          |    8 +-
 drivers/block/nvme-core.c                    |    2 -
 drivers/block/pktcdvd.c                      |   11 ++-
 drivers/block/ps3disk.c                      |    2 -
 drivers/block/ps3vram.c                      |    2 -
 drivers/block/rbd.c                          |    2 -
 drivers/block/rsxx/dma.c                     |    3 +
 drivers/block/umem.c                         |    2 -
 drivers/block/zram/zram_drv.c                |   10 +--
 drivers/dma/ste_dma40.c                      |    5 -
 drivers/iommu/amd_iommu.c                    |   21 ++++-
 drivers/iommu/intel-iommu.c                  |   26 +++++--
 drivers/iommu/iommu.c                        |    2 -
 drivers/md/bcache/btree.c                    |    4 +
 drivers/md/bcache/debug.c                    |    6 +-
 drivers/md/bcache/movinggc.c                 |    2 -
 drivers/md/bcache/request.c                  |    6 +-
 drivers/md/bcache/super.c                    |   10 +--
 drivers/md/bcache/util.c                     |    5 +
 drivers/md/bcache/writeback.c                |    2 -
 drivers/md/dm-crypt.c                        |   12 ++-
 drivers/md/dm-io.c                           |    2 -
 drivers/md/dm-verity.c                       |    2 -
 drivers/md/raid1.c                           |   50 +++++++------
 drivers/md/raid10.c                          |   38 +++++-----
 drivers/md/raid5.c                           |    6 +-
 drivers/mmc/card/queue.c                     |    4 +
 drivers/s390/block/dasd_diag.c               |    2 -
 drivers/s390/block/dasd_eckd.c               |   14 ++--
 drivers/s390/block/dasd_fba.c                |    6 +-
 drivers/s390/block/dcssblk.c                 |    2 -
 drivers/s390/block/scm_blk.c                 |    2 -
 drivers/s390/block/scm_blk_cluster.c         |    2 -
 drivers/s390/block/xpram.c                   |    2 -
 drivers/scsi/mpt2sas/mpt2sas_transport.c     |    6 +-
 drivers/scsi/mpt3sas/mpt3sas_transport.c     |    6 +-
 drivers/scsi/sd_dif.c                        |    4 +
 drivers/staging/android/ion/ion_chunk_heap.c |    4 +
 drivers/staging/lustre/lustre/llite/lloop.c  |    2 -
 drivers/xen/biomerge.c                       |    4 +
 drivers/xen/swiotlb-xen.c                    |   29 +++++--
 fs/btrfs/check-integrity.c                   |    6 +-
 fs/btrfs/compression.c                       |   12 ++-
 fs/btrfs/disk-io.c                           |    4 +
 fs/btrfs/extent_io.c                         |    8 +-
 fs/btrfs/file-item.c                         |    8 +-
 fs/btrfs/inode.c                             |   18 +++--
 fs/btrfs/raid56.c                            |    4 +
 fs/btrfs/volumes.c                           |    2 -
 fs/buffer.c                                  |    4 +
 fs/direct-io.c                               |    2 -
 fs/exofs/ore.c                               |    4 +
 fs/exofs/ore_raid.c                          |    2 -
 fs/ext4/page-io.c                            |    2 -
 fs/f2fs/data.c                               |    4 +
 fs/f2fs/segment.c                            |    2 -
 fs/gfs2/lops.c                               |    4 +
 fs/jfs/jfs_logmgr.c                          |    4 +
 fs/logfs/dev_bdev.c                          |   10 +--
 fs/mpage.c                                   |    2 -
 fs/splice.c                                  |    2 -
 include/asm-generic/dma-mapping-common.h     |   30 ++++++++
 include/asm-generic/memory_model.h           |    4 +
 include/asm-generic/scatterlist.h            |    6 ++
 include/crypto/scatterwalk.h                 |   10 +++
 include/linux/bio.h                          |   24 +++---
 include/linux/blk_types.h                    |   21 +++++
 include/linux/blkdev.h                       |    2 +
 include/linux/dma-debug.h                    |   23 +++++-
 include/linux/dma-mapping.h                  |    8 ++
 include/linux/scatterlist.h                  |  101 ++++++++++++++++++++++++--
 include/linux/swiotlb.h                      |    5 +
 kernel/power/block_io.c                      |    2 -
 lib/dma-debug.c                              |    4 +
 lib/swiotlb.c                                |   20 ++++-
 mm/iov_iter.c                                |   22 +++---
 mm/page_io.c                                 |    8 +-
 net/ceph/messenger.c                         |    2 -
 103 files changed, 658 insertions(+), 335 deletions(-)