Fix up comments about matching flags between bio and rq

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/include/linux/bio.h b/include/linux/bio.h
index dbeb66f..17f1fbd 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -150,8 +150,8 @@
  * bit 3 -- fail fast, don't want low level driver retries
  * bit 4 -- synchronous I/O hint: the block layer will unplug immediately
  */
-#define BIO_RW		0
-#define BIO_RW_AHEAD	1
+#define BIO_RW		0	/* Must match RW in req flags (blkdev.h) */
+#define BIO_RW_AHEAD	1	/* Must match FAILFAST in req flags */
 #define BIO_RW_BARRIER	2
 #define BIO_RW_FAILFAST	3
 #define BIO_RW_SYNC	4
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 53ea933..e0ba018 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -84,7 +84,7 @@
 };
 
 /*
- * request type modified bits. first three bits match BIO_RW* bits, important
+ * request type modified bits. first two bits match BIO_RW* bits, important
  */
 enum rq_flag_bits {
 	__REQ_RW,		/* not set, read. set, write */