Merge tag 'io_uring-worker.v3-2021-02-25' of git://git.kernel.dk/linux-block

Pull io_uring thread rewrite from Jens Axboe:
 "This converts the io-wq workers to be forked off the tasks in question
  instead of being kernel threads that assume various bits of the
  original task identity.

  This kills > 400 lines of code from io_uring/io-wq, and it's the worst
  part of the code. We've had several bugs in this area, and the worry
  is always that we could be missing some pieces for file types doing
  unusual things (recent /dev/tty example comes to mind, userfaultfd
  reads installing file descriptors is another fun one... - both of
  which need special handling, and I bet it's not the last weird oddity
  we'll find).

  With these identical workers, we can have full confidence that we're
  never missing anything. That, in itself, is a huge win. Outside of
  that, it's also more efficient since we're not wasting space and code
  on tracking state, or switching between different states.

  I'm sure we're go...