None of the other blk-mq elevator hooks are called with this lock held.
Additionally, it can lead to circular locking dependencies between
queue_lock and the private scheduler lock.
Reported-by: NPaolo Valente <paolo.valente@linaro.org>
Signed-off-by: NOmar Sandoval <osandov@fb.com>
Signed-off-by: NJens Axboe <axboe@fb.com>