Fix btrfs_wait_ordered_extent_range to properly wait

Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c
index d9c69e1..45127e4 100644
--- a/fs/btrfs/file-item.c
+++ b/fs/btrfs/file-item.c
@@ -161,7 +161,8 @@
 
 	while(bio_index < bio->bi_vcnt) {
 		offset = page_offset(bvec->bv_page) + bvec->bv_offset;
-		if (offset >= ordered->file_offset + ordered->len) {
+		if (offset >= ordered->file_offset + ordered->len ||
+		    offset < ordered->file_offset) {
 			unsigned long bytes_left;
 			sums->len = this_sum_bytes;
 			this_sum_bytes = 0;