UPSTREAM: io_uring: avoid io-wq -EAGAIN looping for !IOPOLL

[ Upstream commit e0deb6a0 ]

If an opcode handler semi-reliably returns -EAGAIN, io_wq_submit_work()
might continue busily hammer the same handler over and over again, which
is not ideal. The -EAGAIN handling in question was put there only for
IOPOLL, so restrict it to IOPOLL mode only where there is no other
recourse than to retry as we cannot wait.

Fixes: def596e9 ("io_uring: support for IO polling")
Change-Id: Ic0a0a689c28f1693f40a25f10392fb3797eae74a
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/f168b4f24181942f3614dd8ff648221736f572e6.1652433740.git.asml.silence@gmail.com


Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
(cherry picked from commit 51ebf1b6)
Bug: 268174392
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>