[PATCH 5/8] blk-mq: add tagset quiesce interface

[Chao Leng]

Reviewed-by: Chao Leng <lengchao at huawei.com>

On 2022/10/20 18:56, Christoph Hellwig wrote:
> From: Chao Leng <lengchao at huawei.com>
> 
> Drivers that have shared tagsets may need to quiesce potentially a lot
> of request queues that all share a single tagset (e.g. nvme). Add an
> interface to quiesce all the queues on a given tagset. This interface is
> useful because it can speedup the quiesce by doing it in parallel.
> 
> Because some queues should not need to be quiesced(e.g. nvme connect_q)
> when quiesce the tagset. So introduce QUEUE_FLAG_SKIP_TAGSET_QUIESCE to
> tagset quiesce interface to skip the queue.
> 
> Signed-off-by: Chao Leng <lengchao at huawei.com>
> [hch: simplify for the per-tag_set srcu_struct]
> Signed-off-by: Christoph Hellwig <hch at lst.de>
> ---
>   block/blk-mq.c         | 25 +++++++++++++++++++++++++
>   include/linux/blk-mq.h |  2 ++
>   include/linux/blkdev.h |  3 +++
>   3 files changed, 30 insertions(+)
> 
> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index cf8f9f9a96c35..b0d2dd56bfdf2 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -313,6 +313,31 @@ void blk_mq_unquiesce_queue(struct request_queue *q)
>   }
>   EXPORT_SYMBOL_GPL(blk_mq_unquiesce_queue);
>   
> +void blk_mq_quiesce_tagset(struct blk_mq_tag_set *set)
> +{
> +	struct request_queue *q;
> +
> +	mutex_lock(&set->tag_list_lock);
> +	list_for_each_entry(q, &set->tag_list, tag_set_list) {
> +		if (!blk_queue_skip_tagset_quiesce(q))
> +			blk_mq_quiesce_queue_nowait(q);
> +	}
> +	blk_mq_wait_quiesce_done(set);
> +	mutex_unlock(&set->tag_list_lock);
> +}
> +EXPORT_SYMBOL_GPL(blk_mq_quiesce_tagset);
> +
> +void blk_mq_unquiesce_tagset(struct blk_mq_tag_set *set)
> +{
> +	struct request_queue *q;
> +
> +	mutex_lock(&set->tag_list_lock);
> +	list_for_each_entry(q, &set->tag_list, tag_set_list)
> +		blk_mq_unquiesce_queue(q);
> +	mutex_unlock(&set->tag_list_lock);
> +}
> +EXPORT_SYMBOL_GPL(blk_mq_unquiesce_tagset);
> +
>   void blk_mq_wake_waiters(struct request_queue *q)
>   {
>   	struct blk_mq_hw_ctx *hctx;
> diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
> index dfd565c4fb84e..35747949f7739 100644
> --- a/include/linux/blk-mq.h
> +++ b/include/linux/blk-mq.h
> @@ -882,6 +882,8 @@ void blk_mq_start_stopped_hw_queue(struct blk_mq_hw_ctx *hctx, bool async);
>   void blk_mq_start_stopped_hw_queues(struct request_queue *q, bool async);
>   void blk_mq_quiesce_queue(struct request_queue *q);
>   void blk_mq_wait_quiesce_done(struct blk_mq_tag_set *set);
> +void blk_mq_quiesce_tagset(struct blk_mq_tag_set *set);
> +void blk_mq_unquiesce_tagset(struct blk_mq_tag_set *set);
>   void blk_mq_unquiesce_queue(struct request_queue *q);
>   void blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs);
>   void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async);
> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
> index b15b6a011c028..854b4745cdd1f 100644
> --- a/include/linux/blkdev.h
> +++ b/include/linux/blkdev.h
> @@ -571,6 +571,7 @@ struct request_queue {
>   #define QUEUE_FLAG_HCTX_ACTIVE	28	/* at least one blk-mq hctx is active */
>   #define QUEUE_FLAG_NOWAIT       29	/* device supports NOWAIT */
>   #define QUEUE_FLAG_SQ_SCHED     30	/* single queue style io dispatch */
> +#define QUEUE_FLAG_SKIP_TAGSET_QUIESCE	31 /* quiesce_tagset skip the queue*/
>   
>   #define QUEUE_FLAG_MQ_DEFAULT	((1UL << QUEUE_FLAG_IO_STAT) |		\
>   				 (1UL << QUEUE_FLAG_SAME_COMP) |	\
> @@ -610,6 +611,8 @@ bool blk_queue_flag_test_and_set(unsigned int flag, struct request_queue *q);
>   #define blk_queue_pm_only(q)	atomic_read(&(q)->pm_only)
>   #define blk_queue_registered(q)	test_bit(QUEUE_FLAG_REGISTERED, &(q)->queue_flags)
>   #define blk_queue_sq_sched(q)	test_bit(QUEUE_FLAG_SQ_SCHED, &(q)->queue_flags)
> +#define blk_queue_skip_tagset_quiesce(q) \
> +	test_bit(QUEUE_FLAG_SKIP_TAGSET_QUIESCE, &(q)->queue_flags)
>   
>   extern void blk_set_pm_only(struct request_queue *q);
>   extern void blk_clear_pm_only(struct request_queue *q);
>