We now wrap sbitmap waitqueues in an active counter, so we can avoid
iterating wakeups unless we have waiters there. This works as long as
everyone that's manipulating the waitqueues use the proper helpers. For
the tag wait case for shared tags, however, we add ourselves to the
waitqueue without incrementing/decrementing the ->ws_active count. This
means that wakeups can take a long time to happen.

Fix this by manually doing the inc/dec as needed for the wait queue
handling.
Reported-by: NMichael Leun <kbug@newton.leun.net>
Tested-by: NMichael Leun <kbug@newton.leun.net>
Cc: stable@vger.kernel.org
Reviewed-by: NOmar Sandoval <osandov@fb.com>
Fixes: 5d2ee712 ("sbitmap: optimize wakeup check")
Signed-off-by: NJens Axboe <axboe@kernel.dk>