blkcg: make blkcg_policy methods take a pointer to blkcg_policy_data

The newly added ->pd_alloc_fn() and ->pd_free_fn() deal with pd
(blkg_policy_data) while the older ones use blkg (blkcg_gq).  As using
blkg doesn't make sense for ->pd_alloc_fn() and after allocation pd
can always be mapped to blkg and given that these are policy-specific
methods, it makes sense to converge on pd.

This patch makes all methods deal with pd instead of blkg.  Most
conversions are trivial.  In blk-cgroup.c, a couple method invocation
sites now test whether pd exists instead of policy state for
consistency.  This shouldn't cause any behavioral differences.

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

1 files changed, 7 insertions, 6 deletions

diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index c3a235b8ec7e..c2c75477a6b2 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -377,9 +377,10 @@ static struct blkg_policy_data *throtl_pd_alloc(gfp_t gfp, int node)
         return &tg->pd;
 }
 
-static void throtl_pd_init(struct blkcg_gq *blkg)
+static void throtl_pd_init(struct blkg_policy_data *pd)
 {
-        struct throtl_grp *tg = blkg_to_tg(blkg);
+        struct throtl_grp *tg = pd_to_tg(pd);
+        struct blkcg_gq *blkg = tg_to_blkg(tg);
         struct throtl_data *td = blkg->q->td;
         struct throtl_service_queue *sq = &tg->service_queue;
 
@@ -417,13 +418,13 @@ static void tg_update_has_rules(struct throtl_grp *tg)
                                     (tg->bps[rw] != -1 || tg->iops[rw] != -1);
 }
 
-static void throtl_pd_online(struct blkcg_gq *blkg)
+static void throtl_pd_online(struct blkg_policy_data *pd)
 {
         /*
          * We don't want new groups to escape the limits of its ancestors.
          * Update has_rules[] after a new group is brought online.
          */
-        tg_update_has_rules(blkg_to_tg(blkg));
+        tg_update_has_rules(pd_to_tg(pd));
 }
 
 static void throtl_pd_free(struct blkg_policy_data *pd)
@@ -435,9 +436,9 @@ static void throtl_pd_free(struct blkg_policy_data *pd)
         kfree(tg);
 }
 
-static void throtl_pd_reset_stats(struct blkcg_gq *blkg)
+static void throtl_pd_reset_stats(struct blkg_policy_data *pd)
 {
-        struct throtl_grp *tg = blkg_to_tg(blkg);
+        struct throtl_grp *tg = pd_to_tg(pd);
         int cpu;
 
         for_each_possible_cpu(cpu) {