--- loop.c	2006-05-04 18:48:34.000000000 -0700
+++ loop.c	2006-05-04 18:52:42.000000000 -0700
@@ -467,16 +467,53 @@
 	return ret;
 }
 
+/*
+ * This is best effort. We really wouldn't know what to do with a returned
+ * error. This code is taken from the implementation of fsync.
+ */
+static void sync_file(struct file * file)  
+{
+        struct address_space *mapping;
+
+        if (!file->f_op || !file->f_op->fsync)
+		return;
+
+        mapping = file->f_mapping;
+
+        current->flags |= PF_SYNCWRITE;
+        filemap_fdatawrite(mapping);
+
+        /*
+         * We need to protect against concurrent writers,
+         * which could cause livelocks in fsync_buffers_list
+         */
+        mutex_lock(&mapping->host->i_mutex);
+        file->f_op->fsync(file, file->f_dentry, 1);
+        mutex_unlock(&mapping->host->i_mutex);
+
+        filemap_fdatawait(mapping);
+        current->flags &= ~PF_SYNCWRITE;
+}
+
 static int do_bio_filebacked(struct loop_device *lo, struct bio *bio)
 {
 	loff_t pos;
 	int ret;
+	int sync = bio_sync(bio);
+	int barrier = bio_barrier(bio);
+
+	if (barrier)
+		sync_file(lo->lo_backing_file);
 
 	pos = ((loff_t) bio->bi_sector << 9) + lo->lo_offset;
 	if (bio_rw(bio) == WRITE)
 		ret = lo_send(lo, bio, lo->lo_blocksize, pos);
 	else
 		ret = lo_receive(lo, bio, lo->lo_blocksize, pos);
+
+	if (barrier || sync)
+		sync_file(lo->lo_backing_file);
+
 	return ret;
 }