[PATCH v4 5.12 0/8] remove task file notes

[Pavel Begunkov <asml.silence@gmail.com>]

Introduce a mapping from ctx to all tctx, and using that removes
file notes, i.e. taking a io_uring file note previously stored in
task->io_uring->xa. It's needed because we don't free io_uring ctx
until all submitters die/exec, and it became worse after killing
 ->flush(). There are rough corner in a form of not behaving nicely,
I'll address in follow-up patches. Also use it to do cancellations
right.

The torture is as simple as below. It will get OOM in no time. Also,
I plan to use it to fix recently broken cancellations.

while (1) {
	assert(!io_uring_queue_init(8, &ring, 0));
	io_uring_queue_exit(&ring);
}

WARNING: hangs without reverting sq park refactoring

v2: rebase (resolve conflicts)
    drop taken 2 patches
v3: use jiffies in 6/6 (Jens)
v4: 2 patches, 7/8 fix cancellation regressions

Pavel Begunkov (8):
  io_uring: make del_task_file more forgiving
  io_uring: introduce ctx to tctx back map
  io_uring: do ctx initiated file note removal
  io_uring: don't take task ring-file notes
  io_uring: index io_uring->xa by ctx not file
  io_uring: warn when ring exit takes too long
  io_uring: cancel reqs of all iowq's on ring exit
  io-wq: warn on creating manager awhile exiting

 fs/io-wq.c               |   2 +
 fs/io_uring.c            | 173 ++++++++++++++++++++++++++++++++-------
 include/linux/io_uring.h |   2 +-
 3 files changed, 147 insertions(+), 30 deletions(-)

-- 
2.24.0