nvme: requeue namespace scan on missed AENs

Scanning for namespaces can take some time, so if the target is
reconfigured while the scan is running we may miss a Attached Namespace
Attribute Changed AEN.

Check if the NVME_AER_NOTICE_NS_CHANGED bit is set once the scan has
finished, and requeue scanning to pick up any missed change.

Signed-off-by: Hannes Reinecke <hare@kernel.org>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>

drivers/nvme/host/core.c

@@ -4295,6 +4295,10 @@ static void nvme_scan_work(struct work_struct *work)
 			nvme_scan_ns_sequential(ctrl);
 	}
 	mutex_unlock(&ctrl->scan_lock);
+
+	/* Requeue if we have missed AENs */
+	if (test_bit(NVME_AER_NOTICE_NS_CHANGED, &ctrl->events))
+		nvme_queue_scan(ctrl);
 }
 
 /*