Pull io_uring fixes from Jens Axboe:
- Make sure the head link cancelation includes async work
- Get rid of kiocb_wait_page_queue_init(), makes no sense to have it as
a separate function since you moved it into io_uring itself
- io_import_iovec cleanups (Pavel, me)
- Use system_unbound_wq for ring exit work, to avoid spawning tons of
these if we have tons of rings exiting at the same time
- Fix req->flags overflow flag manipulation (Pavel)
* tag 'io_uring-5.9-2020-08-21' of git://git.kernel.dk/linux-block:
io_uring: kill extra iovec=NULL in import_iovec()
io_uring: comment on kfree(iovec) checks
io_uring: fix racy req->flags modification
io_uring: use system_unbound_wq for ring exit work
io_uring: cleanup io_import_iovec() of pre-mapped request
io_uring: get rid of kiocb_wait_page_queue_init()
io_uring: find and cancel head link async work on files exit