diff --git a/fs/bio.c b/fs/bio.c
index 9d68ddb..3553029 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -547,11 +547,11 @@
 int bio_uncopy_user(struct bio *bio)
 {
 	struct bio_map_data *bmd = bio->bi_private;
-	int ret;
+	int ret = 0;
 
-	ret = __bio_copy_iov(bio, bmd->iovecs, bmd->sgvecs, bmd->nr_sgvecs, 1,
-			     bmd->is_our_pages);
-
+	if (!bio_flagged(bio, BIO_NULL_MAPPED))
+		ret = __bio_copy_iov(bio, bmd->iovecs, bmd->sgvecs,
+				     bmd->nr_sgvecs, 1, bmd->is_our_pages);
 	bio_free_map_data(bmd);
 	bio_put(bio);
 	return ret;