libnvdimm, pmem: flush posted-write queues on shutdown

Commit writes to media on system shutdown or pmem driver unload.
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

drivers/nvdimm/bus.c

@@ -136,6 +136,21 @@ static int nvdimm_bus_remove(struct device *dev)
 	return rc;
 }
 
+static void nvdimm_bus_shutdown(struct device *dev)
+{
+	struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(dev);
+	struct nd_device_driver *nd_drv = NULL;
+
+	if (dev->driver)
+		nd_drv = to_nd_device_driver(dev->driver);
+
+	if (nd_drv && nd_drv->shutdown) {
+		nd_drv->shutdown(dev);
+		dev_dbg(&nvdimm_bus->dev, "%s.shutdown(%s)\n",
+				dev->driver->name, dev_name(dev));
+	}
+}
+
 void nd_device_notify(struct device *dev, enum nvdimm_event event)
 {
 	device_lock(dev);
@@ -214,6 +229,7 @@ static struct bus_type nvdimm_bus_type = {
 	.match = nvdimm_bus_match,
 	.probe = nvdimm_bus_probe,
 	.remove = nvdimm_bus_remove,
+	.shutdown = nvdimm_bus_shutdown,
 };
 
 static ASYNC_DOMAIN_EXCLUSIVE(nd_async_domain);

drivers/nvdimm/pmem.c

@@ -349,9 +349,16 @@ static int nd_pmem_remove(struct device *dev)
 {
 	if (is_nd_btt(dev))
 		nvdimm_namespace_detach_btt(to_nd_btt(dev));
+	nvdimm_flush(to_nd_region(dev->parent));
+
 	return 0;
 }
 
+static void nd_pmem_shutdown(struct device *dev)
+{
+	nvdimm_flush(to_nd_region(dev->parent));
+}
+
 static void nd_pmem_notify(struct device *dev, enum nvdimm_event event)
 {
 	struct pmem_device *pmem = dev_get_drvdata(dev);
@@ -391,6 +398,7 @@ static struct nd_device_driver nd_pmem_driver = {
 	.probe = nd_pmem_probe,
 	.remove = nd_pmem_remove,
 	.notify = nd_pmem_notify,
+	.shutdown = nd_pmem_shutdown,
 	.drv = {
 		.name = "nd_pmem",
 	},

include/linux/nd.h

@@ -26,6 +26,7 @@ struct nd_device_driver {
 	unsigned long type;
 	int (*probe)(struct device *dev);
 	int (*remove)(struct device *dev);
+	void (*shutdown)(struct device *dev);
 	void (*notify)(struct device *dev, enum nvdimm_event event);
 };