blkcg: use q and plid instead of opaque void * for blkio_group association

blkgio_group is association between a block cgroup and a queue for a
given policy.  Using opaque void * for association makes things
confusing and hinders factoring of common code.  Use request_queue *
and, if necessary, policy id instead.

This will help block cgroup API cleanup.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 16 insertions, 14 deletions

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 0f7a81fc7c73..37e2da9cbb09 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -1020,7 +1020,8 @@ static inline struct cfq_group *cfqg_of_blkg(struct blkio_group *blkg)
         return NULL;
 }
 
-static void cfq_update_blkio_group_weight(void *key, struct blkio_group *blkg,
+static void cfq_update_blkio_group_weight(struct request_queue *q,
+                                          struct blkio_group *blkg,
                                           unsigned int weight)
 {
         struct cfq_group *cfqg = cfqg_of_blkg(blkg);
@@ -1043,10 +1044,10 @@ static void cfq_init_add_cfqg_lists(struct cfq_data *cfqd,
         if (bdi->dev) {
                 sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
                 cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg,
-                                        (void *)cfqd, MKDEV(major, minor));
+                                        cfqd->queue, MKDEV(major, minor));
         } else
                 cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg,
-                                        (void *)cfqd, 0);
+                                        cfqd->queue, 0);
 
         cfqd->nr_blkcg_linked_grps++;
         cfqg->weight = blkcg_get_weight(blkcg, cfqg->blkg.dev);
@@ -1097,7 +1098,6 @@ static struct cfq_group *
 cfq_find_cfqg(struct cfq_data *cfqd, struct blkio_cgroup *blkcg)
 {
         struct cfq_group *cfqg = NULL;
-        void *key = cfqd;
         struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info;
         unsigned int major, minor;
 
@@ -1108,7 +1108,8 @@ cfq_find_cfqg(struct cfq_data *cfqd, struct blkio_cgroup *blkcg)
         if (blkcg == &blkio_root_cgroup)
                 cfqg = &cfqd->root_group;
         else
-                cfqg = cfqg_of_blkg(blkiocg_lookup_group(blkcg, key));
+                cfqg = cfqg_of_blkg(blkiocg_lookup_group(blkcg, cfqd->queue,
+                                                         BLKIO_POLICY_PROP));
 
         if (cfqg && !cfqg->blkg.dev && bdi->dev && dev_name(bdi->dev)) {
                 sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
@@ -1247,21 +1248,22 @@ static bool cfq_release_cfq_groups(struct cfq_data *cfqd)
  * any pending IO in the group is finished.
  *
  * This function is called under rcu_read_lock(). key is the rcu protected
- * pointer. That means "key" is a valid cfq_data pointer as long as we are rcu
- * read lock.
+ * pointer. That means @q is a valid request_queue pointer as long as we
+ * are rcu read lock.
  *
- * "key" was fetched from blkio_group under blkio_cgroup->lock. That means
+ * @q was fetched from blkio_group under blkio_cgroup->lock. That means
  * it should not be NULL as even if elevator was exiting, cgroup deltion
  * path got to it first.
  */
-static void cfq_unlink_blkio_group(void *key, struct blkio_group *blkg)
+static void cfq_unlink_blkio_group(struct request_queue *q,
+                                   struct blkio_group *blkg)
 {
-        unsigned long  flags;
-        struct cfq_data *cfqd = key;
+        struct cfq_data *cfqd = q->elevator->elevator_data;
+        unsigned long flags;
 
-        spin_lock_irqsave(cfqd->queue->queue_lock, flags);
+        spin_lock_irqsave(q->queue_lock, flags);
         cfq_destroy_cfqg(cfqd, cfqg_of_blkg(blkg));
-        spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
+        spin_unlock_irqrestore(q->queue_lock, flags);
 }
 
 static struct elevator_type iosched_cfq;
@@ -3718,7 +3720,7 @@ static int cfq_init_queue(struct request_queue *q)
         rcu_read_lock();
 
         cfq_blkiocg_add_blkio_group(&blkio_root_cgroup, &cfqg->blkg,
-                                        (void *)cfqd, 0);
+                                    cfqd->queue, 0);
         rcu_read_unlock();
         cfqd->nr_blkcg_linked_grps++;