--- linux-2.6.16/drivers/block/loop.c~	2006-06-29 13:22:37.000000000 +0200
+++ linux-2.6.16/drivers/block/loop.c	2006-06-29 13:28:17.000000000 +0200
@@ -467,16 +467,58 @@
 	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 int sync_file(struct file * file)  
+{
+	struct address_space *mapping;
+	int ret;
+
+	if (!file->f_op || !file->f_op->fsync)
+		return -EOPNOTSUPP;
+
+	mapping = file->f_mapping;
+
+	ret = filemap_fdatawrite(mapping);
+	if (!ret) {
+		/*
+		 * We need to protect against concurrent writers,
+		 * which could cause livelocks in fsync_buffers_list
+		 */
+		mutex_lock(&mapping->host->i_mutex);
+		ret = file->f_op->fsync(file, file->f_dentry, 1);
+		mutex_unlock(&mapping->host->i_mutex);
+
+		filemap_fdatawait(mapping);
+	}
+
+	return ret;
+}
+
 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) {
+		ret = sync_file(lo->lo_backing_file);
+		if (unlikely(ret))
+			return ret;
+	}
 
 	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) && !ret)
+		ret = sync_file(lo->lo_backing_file);
+
 	return ret;
 }