diff --git a/[refs] b/[refs]
index b57f286666ce..232520cdcbe4 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 905386f82d08f66726912f303f3e6605248c60a3
+refs/heads/master: 600497013687516153cb82637acfe56f7eb9308a
diff --git a/trunk/drivers/md/dm-thin.c b/trunk/drivers/md/dm-thin.c
index 423df92f1c19..7510cb3d571c 100644
--- a/trunk/drivers/md/dm-thin.c
+++ b/trunk/drivers/md/dm-thin.c
@@ -1315,7 +1315,7 @@ static void process_shared_bio(struct thin_c *tc, struct bio *bio,
 	if (bio_detain(pool->prison, &key, bio, &cell))
 		return;
 
-	if (bio_data_dir(bio) == WRITE)
+	if (bio_data_dir(bio) == WRITE && bio->bi_size)
 		break_sharing(tc, bio, block, &key, lookup_result, cell);
 	else {
 		struct dm_thin_endio_hook *h = dm_get_mapinfo(bio)->ptr;