Merge branch 'for-5.8/block' into for-next

Merge branch 'for-5.8/block' into for-next

* for-5.8/block:
  block: Remove unused flush_queue_delayed in struct blk_flush_queue
  null_blk: Zero-initialize read buffers in non-memory-backed mode
  block: Document the bio_vec properties
  bio.h: Declare the arguments of the bio iteration functions const
  block: Fix type of first compat_put_{,u}long() argument
  block: merge part_{inc,dev}_in_flight into their only callers
  block: don't call part_{inc,dec}_in_flight for blk-mq devices
  block: move the blk-mq calls out of part_in_flight{,_rw}
  block: mark blk_account_io_completion static
  blk-mq: allow blk_mq_make_request to consume the q_usage_counter reference
  blk-mq: remove a pointless queue enter pair in blk_mq_alloc_request_hctx
  blk-mq: remove a pointless queue enter pair in blk_mq_alloc_request
  blk-mq: move the call to blk_queue_enter_live out of blk_mq_get_request