- * at this point, the device is zero sized and detached from
- * the devices list. All that's left is to zero out the old
- * supers and free the device.
+ * At this point, the device is zero sized and detached from the
+ * devices list. All that's left is to zero out the old supers and
+ * free the device.
+ *
+ * We cannot call btrfs_close_bdev() here because we're holding the sb
+ * write lock, and blkdev_put() will pull in the ->open_mutex on the
+ * block device and it's dependencies. Instead just flush the device
+ * and let the caller do the final blkdev_put.