[PATCH 17/17] nvme: use blk_mq_[un]quiesce_tagset

[Christoph Hellwig]

From: Chao Leng <lengchao at huawei.com>

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.

Currently 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: Chao Leng <lengchao at huawei.com>
[hch: rebased on top of prep patches]
Signed-off-by: Christoph Hellwig <hch at lst.de>
Reviewed-by: Keith Busch <kbusch at kernel.org>
Reviewed-by: Chao Leng <lengchao at huawei.com>
Reviewed-by: Hannes Reinecke <hare at suse.de>
---
 drivers/nvme/host/core.c | 34 ++++++++--------------------------
 drivers/nvme/host/nvme.h |  2 +-
 2 files changed, 9 insertions(+), 27 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 012ef0772f5b3..ff9ed2467fb30 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -4880,6 +4880,8 @@ 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;
@@ -5079,20 +5081,6 @@ int nvme_init_ctrl(struct nvme_ctrl *ctrl, struct device *dev,
 }
 EXPORT_SYMBOL_GPL(nvme_init_ctrl);
 
-static void nvme_start_ns_queue(struct nvme_ns *ns)
-{
-	if (test_and_clear_bit(NVME_NS_STOPPED, &ns->flags))
-		blk_mq_unquiesce_queue(ns->queue);
-}
-
-static void nvme_stop_ns_queue(struct nvme_ns *ns)
-{
-	if (!test_and_set_bit(NVME_NS_STOPPED, &ns->flags))
-		blk_mq_quiesce_queue(ns->queue);
-	else
-		blk_mq_wait_quiesce_done(ns->queue->tag_set);
-}
-
 /* let I/O to all namespaces fail in preparation for surprise removal */
 void nvme_mark_namespaces_dead(struct nvme_ctrl *ctrl)
 {
@@ -5155,23 +5143,17 @@ EXPORT_SYMBOL_GPL(nvme_start_freeze);
 
 void nvme_stop_queues(struct nvme_ctrl *ctrl)
 {
-	struct nvme_ns *ns;
-
-	down_read(&ctrl->namespaces_rwsem);
-	list_for_each_entry(ns, &ctrl->namespaces, list)
-		nvme_stop_ns_queue(ns);
-	up_read(&ctrl->namespaces_rwsem);
+	if (!test_and_set_bit(NVME_CTRL_STOPPED, &ctrl->flags))
+		blk_mq_quiesce_tagset(ctrl->tagset);
+	else
+		blk_mq_wait_quiesce_done(ctrl->tagset);
 }
 EXPORT_SYMBOL_GPL(nvme_stop_queues);
 
 void nvme_start_queues(struct nvme_ctrl *ctrl)
 {
-	struct nvme_ns *ns;
-
-	down_read(&ctrl->namespaces_rwsem);
-	list_for_each_entry(ns, &ctrl->namespaces, list)
-		nvme_start_ns_queue(ns);
-	up_read(&ctrl->namespaces_rwsem);
+	if (test_and_clear_bit(NVME_CTRL_STOPPED, &ctrl->flags))
+		blk_mq_unquiesce_tagset(ctrl->tagset);
 }
 EXPORT_SYMBOL_GPL(nvme_start_queues);
 
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 1cd7168002438..f9df10653f3c5 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -237,6 +237,7 @@ enum nvme_ctrl_flags {
 	NVME_CTRL_FAILFAST_EXPIRED	= 0,
 	NVME_CTRL_ADMIN_Q_STOPPED	= 1,
 	NVME_CTRL_STARTED_ONCE		= 2,
+	NVME_CTRL_STOPPED		= 3,
 };
 
 struct nvme_ctrl {
@@ -486,7 +487,6 @@ struct nvme_ns {
 #define NVME_NS_ANA_PENDING	2
 #define NVME_NS_FORCE_RO	3
 #define NVME_NS_READY		4
-#define NVME_NS_STOPPED		5
 
 	struct cdev		cdev;
 	struct device		cdev_device;
-- 
2.30.2