Pull io_uring fixes from Jens Axboe:
 "As sometimes happens, two reports came in around the merge window open
  that led to some fixes. Hence this one is a bit bigger than usual
  followup fixes, but most of it will be going towards stable, outside
  of the fixes that are addressing regressions from this merge window.

  In detail:

   - postgres is a heavy user of signals between tasks, and if we're
     unlucky this can interfere with io-wq worker creation. Make sure
     we're resilient against unrelated signal handling. This set of
     changes also includes hardening against allocation failures, which
     could previously had led to stalls.

   - Some use cases that end up having a mix of bounded and unbounded
     work would have starvation issues related to that. Split the
     pending work lists to handle that better.

   - Completion trace int -> unsigned -> long fix

   - Fix issue with REGISTER_IOWQ_MAX_WORKERS and SQPOLL

   - Fix regression with hash wait lock in this merge window

   - Fix retry issued on block devices (Ming)

   - Fix regression with links in this merge window (Pavel)

   - Fix race with multi-shot poll and completions (Xiaoguang)

   - Ensure regular file IO doesn't inadvertently skip completion
     batching (Pavel)

   - Ensure submissions are flushed after running task_work (Pavel)"

* tag 'for-5.15/io_uring-2021-09-04' of git://git.kernel.dk/linux-block:
  io_uring: io_uring_complete() trace should take an integer
  io_uring: fix possible poll event lost in multi shot mode
  io_uring: prolong tctx_task_work() with flushing
  io_uring: don't disable kiocb_done() CQE batching
  io_uring: ensure IORING_REGISTER_IOWQ_MAX_WORKERS works with SQPOLL
  io-wq: make worker creation resilient against signals
  io-wq: get rid of FIXED worker flag
  io-wq: only exit on fatal signals
  io-wq: split bounded and unbounded work into separate lists
  io-wq: fix queue stalling race
  io_uring: don't submit half-prepared drain request
  io_uring: fix queueing half-created requests
  io-wq: ensure that hash wait lock is IRQ disabling
  io_uring: retry in case of short read on block device
  io_uring: IORING_OP_WRITE needs hash_reg_file set
  io-wq: fix race between adding work and activating a free worker