[PATCH 6/7] nvmet: make fused commands be atomic

[Dmitry Bogdanov]

Ensure that the fused commands are executed in atomic manner. One Fused
pair per whole namespace.

Signed-off-by: Dmitry Bogdanov <d.bogdanov at yadro.com>
---
 drivers/nvme/target/core.c  | 6 ++++++
 drivers/nvme/target/nvmet.h | 1 +
 2 files changed, 7 insertions(+)

diff --git a/drivers/nvme/target/core.c b/drivers/nvme/target/core.c
index d5cc760ba2f4..1ab6d8f7a7b1 100644
--- a/drivers/nvme/target/core.c
+++ b/drivers/nvme/target/core.c
@@ -705,6 +705,7 @@ struct nvmet_ns *nvmet_ns_alloc(struct nvmet_subsys *subsys, u32 nsid)
 	uuid_gen(&ns->uuid);
 	ns->buffered_io = false;
 	ns->csi = NVME_CSI_NVM;
+	sema_init(&ns->caw_lock, 1);
 
 	return ns;
 }
@@ -872,6 +873,8 @@ static void __nvmet_fused_req_complete(struct nvmet_req *req,
 		spin_unlock(&second_req->fused_lock);
 		spin_unlock_irqrestore(&first_req->fused_lock, flags);
 
+		up(&req->ns->caw_lock);
+
 		if (first_req->ns)
 			nvmet_put_namespace(first_req->ns);
 		first_req->ops->queue_response(first_req);
@@ -1376,6 +1379,8 @@ void nvmet_req_execute(struct nvmet_req *req)
 			if (req->fused_pair->fused_state == NVMET_FUSED_STATE_EXECUTING) {
 				spin_unlock(&req->fused_pair->fused_lock);
 				spin_unlock(&req->fused_lock);
+
+				down(&req->ns->caw_lock);
 				req->execute(req);
 				return;
 			}
@@ -1411,6 +1416,7 @@ void nvmet_req_execute(struct nvmet_req *req)
 			spin_unlock(&req->fused_lock);
 			spin_unlock(&first_req->fused_lock);
 			/* both fused command are ready to execute */
+			down(&req->ns->caw_lock);
 			first_req->execute(first_req);
 			return;
 		}
diff --git a/drivers/nvme/target/nvmet.h b/drivers/nvme/target/nvmet.h
index 1278b81c85a7..1dc9814c7a8c 100644
--- a/drivers/nvme/target/nvmet.h
+++ b/drivers/nvme/target/nvmet.h
@@ -85,6 +85,7 @@ struct nvmet_ns {
 	int			pi_type;
 	int			metadata_size;
 	u8			csi;
+	struct semaphore	caw_lock;
 };
 
 static inline struct nvmet_ns *to_nvmet_ns(struct config_item *item)
-- 
2.25.1