[PATCH V3 6/6] blk-mq: support concurrent queue quiesce/unquiesce

[Christoph Hellwig]

On Sat, Oct 09, 2021 at 11:47:13AM +0800, Ming Lei wrote:
> +	spin_lock_irqsave(&q->queue_lock, flags);
> +	if (!q->quiesce_depth++)
> +		blk_queue_flag_set(QUEUE_FLAG_QUIESCED, q);

We can get rid of the QUEUE_FLAG_QUIESCED flag now and just look
at ->quiesce_depth directly.

> +	spin_lock_irqsave(&q->queue_lock, flags);
> +	WARN_ON_ONCE(q->quiesce_depth <= 0);
> +	if (q->quiesce_depth > 0 && !--q->quiesce_depth) {

	if (WARN_ON_ONCE(q->quiesce_depth <= 0))
		; /* oops */
	else if (!--q->quiesce_depth)
		run_queue = true;

Otherwise this looks sensible.