[PATCH v3 0/9] Add support for segments smaller than one page

[Bart Van Assche <bvanassche@acm.org>]

Hi Jens,

Several embedded storage controllers need support for DMA segments that are
smaller than the size of one virtual memory page. Hence this patch series.
Please consider this patch series for the next merge window.

Thanks,

Bart.

Changes compared to v2:
- For SCSI drivers, only set flag QUEUE_FLAG_SUB_PAGE_SEGMENTS if necessary.
- In the scsi_debug patch, sorted kernel module parameters alphabetically.
  Only set flag QUEUE_FLAG_SUB_PAGE_SEGMENTS if necessary.
- Added a patch for the UFS Exynos driver that enables
  CONFIG_BLK_SUB_PAGE_SEGMENTS if the page size exceeds 4 KiB.

Changes compared to v1:
- Added a CONFIG variable that controls whether or not small segment support
  is enabled.
- Improved patch descriptions.

Bart Van Assche (9):
  block: Introduce QUEUE_FLAG_SUB_PAGE_SEGMENTS and
    CONFIG_BLK_SUB_PAGE_SEGMENTS
  block: Support configuring limits below the page size
  block: Support submitting passthrough requests with small segments
  block: Add support for filesystem requests and small segments
  block: Add support for small segments in blk_rq_map_user_iov()
  scsi_debug: Support configuring the maximum segment size
  null_blk: Support configuring the maximum segment size
  scsi: core: Set BLK_SUB_PAGE_SEGMENTS for small max_segment_size
    values
  scsi: ufs: exynos: Select CONFIG_BLK_SUB_PAGE_SEGMENTS for lage page
    sizes

 block/Kconfig                     |  9 +++++++
 block/blk-map.c                   | 43 ++++++++++++++++++++++++++-----
 block/blk-merge.c                 |  6 +++--
 block/blk-mq.c                    |  2 ++
 block/blk-settings.c              | 20 ++++++++------
 block/blk.h                       | 22 +++++++++++-----
 drivers/block/null_blk/main.c     | 21 ++++++++++++---
 drivers/block/null_blk/null_blk.h |  1 +
 drivers/scsi/scsi_debug.c         | 15 +++++++++++
 drivers/scsi/scsi_lib.c           |  3 +++
 drivers/ufs/host/Kconfig          |  1 +
 include/linux/blkdev.h            |  7 +++++
 12 files changed, 125 insertions(+), 25 deletions(-)