diff --git a/include/linux/bio.h b/include/linux/bio.h
index da3a127..8bfe9ee 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -645,6 +645,17 @@
 }
 
 /*
+ * Increment chain count for the bio. Make sure the CHAIN flag update
+ * is visible before the raised count.
+ */
+static inline void bio_inc_remaining(struct bio *bio)
+{
+	bio->bi_flags |= (1 << BIO_CHAIN);
+	smp_mb__before_atomic();
+	atomic_inc(&bio->__bi_remaining);
+}
+
+/*
  * bio_set is used to allow other portions of the IO system to
  * allocate their own private memory pools for bio and iovec structures.
  * These memory pools in turn all allocate from the bio_slab
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index a1b25e3..8b07e06 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -65,7 +65,7 @@
 	unsigned int		bi_seg_front_size;
 	unsigned int		bi_seg_back_size;
 
-	atomic_t		bi_remaining;
+	atomic_t		__bi_remaining;
 
 	bio_end_io_t		*bi_end_io;
 
@@ -122,6 +122,7 @@
 #define BIO_NULL_MAPPED 8	/* contains invalid user pages */
 #define BIO_QUIET	9	/* Make BIO Quiet */
 #define BIO_SNAP_STABLE	10	/* bio data must be snapshotted during write */
+#define BIO_CHAIN	11	/* chained bio, ->bi_remaining in effect */
 
 /*
  * Flags starting here get preserved by bio_reset() - this includes