[PATCH 1/2] nvme: make NVMe freeze API reliably

[Ming Lei]

From: Keith Busch <kbusch at kernel.org>

In some corner cases[1], freeze wait and unfreeze API may be called on
unfrozen queue, add one per-ns flag of NVME_NS_FREEZE to make these
freeze APIs more reliably, then this kind of issues can be avoided.
And similar approach has been applied on stopping/quiescing nvme queues.

[1] https://lore.kernel.org/linux-nvme/20220801125753.1434024-1-ming.lei@redhat.com/

Reported-by: Yi Zhang <yi.zhang at redhat.com>
Link: https://lore.kernel.org/linux-block/CAHj4cs--KPTAGP=jj+7KMe=arDv=HeGeOgs1T8vbusyk=EjXow@mail.gmail.com/#r

Add comment log.
Signed-off-by: Ming Lei <ming.lei at redhat.com>
---
 drivers/nvme/host/core.c | 16 +++++++++++++---
 drivers/nvme/host/nvme.h |  1 +
 2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index af367b22871b..fe4ae3616ed1 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -5028,8 +5028,11 @@ void nvme_unfreeze(struct nvme_ctrl *ctrl)
 	struct nvme_ns *ns;
 
 	down_read(&ctrl->namespaces_rwsem);
-	list_for_each_entry(ns, &ctrl->namespaces, list)
+	list_for_each_entry(ns, &ctrl->namespaces, list) {
+		if (!test_and_clear_bit(NVME_NS_FREEZE, &ns->flags))
+			continue;
 		blk_mq_unfreeze_queue(ns->queue);
+	}
 	up_read(&ctrl->namespaces_rwsem);
 }
 EXPORT_SYMBOL_GPL(nvme_unfreeze);
@@ -5040,6 +5043,8 @@ int nvme_wait_freeze_timeout(struct nvme_ctrl *ctrl, long timeout)
 
 	down_read(&ctrl->namespaces_rwsem);
 	list_for_each_entry(ns, &ctrl->namespaces, list) {
+		if (!test_bit(NVME_NS_FREEZE, &ns->flags))
+			continue;
 		timeout = blk_mq_freeze_queue_wait_timeout(ns->queue, timeout);
 		if (timeout <= 0)
 			break;
@@ -5054,8 +5059,11 @@ void nvme_wait_freeze(struct nvme_ctrl *ctrl)
 	struct nvme_ns *ns;
 
 	down_read(&ctrl->namespaces_rwsem);
-	list_for_each_entry(ns, &ctrl->namespaces, list)
+	list_for_each_entry(ns, &ctrl->namespaces, list) {
+		if (!test_bit(NVME_NS_FREEZE, &ns->flags))
+			continue;
 		blk_mq_freeze_queue_wait(ns->queue);
+	}
 	up_read(&ctrl->namespaces_rwsem);
 }
 EXPORT_SYMBOL_GPL(nvme_wait_freeze);
@@ -5065,8 +5073,10 @@ void nvme_start_freeze(struct nvme_ctrl *ctrl)
 	struct nvme_ns *ns;
 
 	down_read(&ctrl->namespaces_rwsem);
-	list_for_each_entry(ns, &ctrl->namespaces, list)
+	list_for_each_entry(ns, &ctrl->namespaces, list) {
+		set_bit(NVME_NS_FREEZE, &ns->flags);
 		blk_freeze_queue_start(ns->queue);
+	}
 	up_read(&ctrl->namespaces_rwsem);
 }
 EXPORT_SYMBOL_GPL(nvme_start_freeze);
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 1bdf714dcd9e..702ba19b5647 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -484,6 +484,7 @@ struct nvme_ns {
 #define NVME_NS_FORCE_RO	3
 #define NVME_NS_READY		4
 #define NVME_NS_STOPPED		5
+#define NVME_NS_FREEZE		6
 
 	struct cdev		cdev;
 	struct device		cdev_device;
-- 
2.31.1