Pull more io_uring fixes from Jens Axboe:
 "Two followup fixes. One is fixing a regression from this merge window,
  the other is two commits fixing cancelation of deferred requests.

  Both have gone through full testing, and both spawned a few new
  regression test additions to liburing.

   - Don't play games with const, properly store the output iovec and
     assign it as needed.

   - Deferred request cancelation fix (Pavel)"

* tag 'io_uring-5.9-2020-09-06' of git://git.kernel.dk/linux-block:
  io_uring: fix linked deferred ->files cancellation
  io_uring: fix cancel of deferred reqs with ->files
  io_uring: fix explicit async read/write mapping for large segments