UBI: block: Add support for the UBI_VOLUME_UPDATED notification

Static volumes can change its 'used_bytes' when they get updated,
and so the block interface must listen to the UBI_VOLUME_UPDATED
notification to resize the block device accordingly.

Signed-off-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Cc: stable@vger.kernel.org # v3.15+

drivers/mtd/ubi/block.c

@@ -524,8 +524,12 @@ static int ubiblock_resize(struct ubi_volume_info *vi)
 	}
 
 	mutex_lock(&dev->dev_mutex);
-	set_capacity(dev->gd, disk_capacity);
-	ubi_msg("%s resized to %lld bytes", dev->gd->disk_name, vi->used_bytes);
+
+	if (get_capacity(dev->gd) != disk_capacity) {
+		set_capacity(dev->gd, disk_capacity);
+		ubi_msg("%s resized to %lld bytes", dev->gd->disk_name,
+			vi->used_bytes);
+	}
 	mutex_unlock(&dev->dev_mutex);
 	mutex_unlock(&devices_mutex);
 	return 0;
@@ -549,6 +553,14 @@ static int ubiblock_notify(struct notifier_block *nb,
 	case UBI_VOLUME_RESIZED:
 		ubiblock_resize(&nt->vi);
 		break;
+	case UBI_VOLUME_UPDATED:
+		/*
+		 * If the volume is static, a content update might mean the
+		 * size (i.e. used_bytes) was also changed.
+		 */
+		if (nt->vi.vol_type == UBI_STATIC_VOLUME)
+			ubiblock_resize(&nt->vi);
+		break;
 	default:
 		break;
 	}