UPSTREAM: io_uring: fix races with buffer table unregister

[ Upstream commit d11d31fc ]

Fixed buffer table quiesce might unlock ->uring_lock, potentially
letting new requests to be submitted, don't allow those requests to
use the table as they will race with unregistration.

Reported-and-tested-by: van fantasy <g1042620637@gmail.com>
Fixes: bd54b6fe ("io_uring: implement fixed buffers registration similar to fixed files")
Change-Id: If99dbeed9ac5fe037ac2ee75bb9156e1c2d3857f
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
(cherry picked from commit 91f5a60a)
Bug: 268174392
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>