xfs: updates for 4.9-rc3

Changes in this update:
o iomap page offset masking fix for page faults
o add IOMAP_REPORT to distinguish between read and fiemap map requests
o cleanups to new shared data extent code
o fix mount active status on failed log recovery
o fix broken dquots in a buffer calculation
o fix locking order issues and merge xfs_reflink_remap_range and
  xfs_file_share_range
o rework unmapping of CoW extents and remove now unused functions
o clean state when CoW is done.