block: move bio io prio to a new field

In the next patch, we move drop the compat code and make
the op a separate value that is hidden in bi_rw. To give
the op and rq bits flags room to grow this moves prio to
its own field.
Signed-off-by: Mike Christie <mchristi@redhat.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

include/linux/bio.h

@@ -47,18 +47,8 @@
 #define bio_op(bio)				(op_from_rq_bits((bio)->bi_rw))
 #define bio_set_op_attrs(bio, op, flags)	((bio)->bi_rw |= (op | flags))
 
-/*
- * upper 16 bits of bi_rw define the io priority of this bio
- */
-#define BIO_PRIO_SHIFT	(8 * sizeof(unsigned long) - IOPRIO_BITS)
-#define bio_prio(bio)	((bio)->bi_rw >> BIO_PRIO_SHIFT)
-#define bio_prio_valid(bio)	ioprio_valid(bio_prio(bio))
-
-#define bio_set_prio(bio, prio)		do {			\
-	WARN_ON(prio >= (1 << IOPRIO_BITS));			\
-	(bio)->bi_rw &= ((1UL << BIO_PRIO_SHIFT) - 1);		\
-	(bio)->bi_rw |= ((unsigned long) (prio) << BIO_PRIO_SHIFT);	\
-} while (0)
+#define bio_prio(bio)			(bio)->bi_ioprio
+#define bio_set_prio(bio, prio)		((bio)->bi_ioprio = prio)
 
 /*
  * various member access, note that bio_data should of course not be used

include/linux/blk_types.h

@@ -48,9 +48,8 @@ struct bio {
 	struct block_device	*bi_bdev;
 	unsigned int		bi_flags;	/* status, command, etc */
 	int			bi_error;
-	unsigned long		bi_rw;		/* bottom bits READ/WRITE,
-						 * top bits priority
-						 */
+	unsigned long		bi_rw;		/* READ/WRITE */
+	unsigned short		bi_ioprio;
 
 	struct bvec_iter	bi_iter;