blkcg: move blkio_group_conf->weight to cfq

blkio_group_conf->weight is owned by cfq and has no reason to be
defined in blkcg core.  Replace it with cfq_group->dev_weight and let
conf setting functions directly set it.  If dev_weight is zero, the
cfqg doesn't have device specific weight configured.

Also, rename BLKIO_WEIGHT_* constants to CFQ_WEIGHT_* and rename
blkio_cgroup->weight to blkio_cgroup->cfq_weight.  We eventually want
per-policy storage in blkio_cgroup but just mark the ownership of the
field for now.

Signed-off-by: Tejun Heo <tj@kernel.org>
diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
index e368dd00..386db29 100644
--- a/block/blk-cgroup.h
+++ b/block/blk-cgroup.h
@@ -29,6 +29,11 @@
 
 #ifdef CONFIG_BLK_CGROUP
 
+/* CFQ specific, out here for blkcg->cfq_weight */
+#define CFQ_WEIGHT_MIN		10
+#define CFQ_WEIGHT_MAX		1000
+#define CFQ_WEIGHT_DEFAULT	500
+
 /* cft->private [un]packing for stat printing */
 #define BLKCG_STAT_PRIV(pol, off)	(((unsigned)(pol) << 16) | (off))
 #define BLKCG_STAT_POL(prv)		((unsigned)(prv) >> 16)
@@ -46,12 +51,14 @@
 
 struct blkio_cgroup {
 	struct cgroup_subsys_state css;
-	unsigned int weight;
 	spinlock_t lock;
 	struct hlist_head blkg_list;
 
 	/* for policies to test whether associated blkcg has changed */
 	uint64_t id;
+
+	/* TODO: per-policy storage in blkio_cgroup */
+	unsigned int cfq_weight;	/* belongs to cfq */
 };
 
 struct blkg_stat {
@@ -65,7 +72,6 @@
 };
 
 struct blkio_group_conf {
-	unsigned int weight;
 	u64 iops[2];
 	u64 bps[2];
 };
@@ -355,10 +361,6 @@
 
 #endif
 
-#define BLKIO_WEIGHT_MIN	10
-#define BLKIO_WEIGHT_MAX	1000
-#define BLKIO_WEIGHT_DEFAULT	500
-
 #ifdef CONFIG_BLK_CGROUP
 extern struct blkio_cgroup blkio_root_cgroup;
 extern struct blkio_cgroup *cgroup_to_blkio_cgroup(struct cgroup *cgroup);