[PATCH v3 2/2] nvme: use blk_mq_[un]quiesce_tagset

[Sagi Grimberg]

On 10/20/22 06:53, Chao Leng wrote:
> All controller namespaces share the same tagset, so we can use this
> interface which does the optimal operation for parallel quiesce based on
> the tagset type(e.g. blocking tagsets and non-blocking tagsets).
> 
> nvme connect_q should not be quiesced when quiesce tagset, so set the
> QUEUE_FLAG_SKIP_TAGSET_QUIESCE to skip it when init connect_q.
> 
> Currntely we use NVME_NS_STOPPED to ensure pairing quiescing and
> unquiescing. If use blk_mq_[un]quiesce_tagset, NVME_NS_STOPPED will be
> invalided, so introduce NVME_CTRL_STOPPED to replace NVME_NS_STOPPED.
> In addition, we never really quiesce a single namespace. It is a better
> choice to move the flag from ns to ctrl.
> 
> Signed-off-by: Sagi Grimberg <sagi at grimberg.me>
> Signed-off-by: Chao Leng <lengchao at huawei.com>
> ---
>   drivers/nvme/host/core.c | 57 +++++++++++++++++++-----------------------------
>   drivers/nvme/host/nvme.h |  3 ++-
>   2 files changed, 25 insertions(+), 35 deletions(-)
> 
> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
> index 059737c1a2c1..c7727d1f228e 100644
> --- a/drivers/nvme/host/core.c
> +++ b/drivers/nvme/host/core.c
> @@ -4890,6 +4890,7 @@ int nvme_alloc_io_tag_set(struct nvme_ctrl *ctrl, struct blk_mq_tag_set *set,
>   			ret = PTR_ERR(ctrl->connect_q);
>   			goto out_free_tag_set;
>   		}
> +		blk_queue_flag_set(QUEUE_FLAG_SKIP_TAGSET_QUIESCE, ctrl->connect_q);
>   	}
>   
>   	ctrl->tagset = set;
> @@ -5013,6 +5014,7 @@ int nvme_init_ctrl(struct nvme_ctrl *ctrl, struct device *dev,
>   	clear_bit(NVME_CTRL_FAILFAST_EXPIRED, &ctrl->flags);
>   	spin_lock_init(&ctrl->lock);
>   	mutex_init(&ctrl->scan_lock);
> +	mutex_init(&ctrl->queue_state_lock);

Why is this lock needed?