nvme: flush reset_work before safely continuing with delete operation

Prevent racing controller reset and delete flows. reset_work must not
ever self-requeue so flushing it suffices.

Reported-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>
diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 4fa748c..003314e 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -102,6 +102,7 @@ static void nvme_delete_ctrl_work(struct work_struct *work)
 	struct nvme_ctrl *ctrl =
 		container_of(work, struct nvme_ctrl, delete_work);
 
+	flush_work(&ctrl->reset_work);
 	nvme_stop_ctrl(ctrl);
 	nvme_remove_namespaces(ctrl);
 	ctrl->ops->delete_ctrl(ctrl);