2 files changed, 16 insertions, 63 deletions

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 694595b29b8f..2998e4f095d1 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -310,28 +310,11 @@ struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
         }
 }
 
-static void blkg_pd_offline(struct blkcg_gq *blkg)
-{
-        int i;
-
-        lockdep_assert_held(blkg->q->queue_lock);
-        lockdep_assert_held(&blkg->blkcg->lock);
-
-        for (i = 0; i < BLKCG_MAX_POLS; i++) {
-                struct blkcg_policy *pol = blkcg_policy[i];
-
-                if (blkg->pd[i] && !blkg->pd[i]->offline &&
-                    pol->pd_offline_fn) {
-                        pol->pd_offline_fn(blkg->pd[i]);
-                        blkg->pd[i]->offline = true;
-                }
-        }
-}
-
 static void blkg_destroy(struct blkcg_gq *blkg)
 {
         struct blkcg *blkcg = blkg->blkcg;
         struct blkcg_gq *parent = blkg->parent;
+        int i;
 
         lockdep_assert_held(blkg->q->queue_lock);
         lockdep_assert_held(&blkcg->lock);
@@ -340,6 +323,13 @@ static void blkg_destroy(struct blkcg_gq *blkg)
         WARN_ON_ONCE(list_empty(&blkg->q_node));
         WARN_ON_ONCE(hlist_unhashed(&blkg->blkcg_node));
 
+        for (i = 0; i < BLKCG_MAX_POLS; i++) {
+                struct blkcg_policy *pol = blkcg_policy[i];
+
+                if (blkg->pd[i] && pol->pd_offline_fn)
+                        pol->pd_offline_fn(blkg->pd[i]);
+        }
+
         if (parent) {
                 blkg_rwstat_add_aux(&parent->stat_bytes, &blkg->stat_bytes);
                 blkg_rwstat_add_aux(&parent->stat_ios, &blkg->stat_ios);
@@ -382,7 +372,6 @@ static void blkg_destroy_all(struct request_queue *q)
                 struct blkcg *blkcg = blkg->blkcg;
 
                 spin_lock(&blkcg->lock);
-                blkg_pd_offline(blkg);
                 blkg_destroy(blkg);
                 spin_unlock(&blkcg->lock);
         }
@@ -1058,54 +1047,21 @@ static struct cftype blkcg_legacy_files[] = {
  * @css: css of interest
  *
  * This function is called when @css is about to go away and responsible
- * for offlining all blkgs pd and killing all wbs associated with @css.
- * blkgs pd offline should be done while holding both q and blkcg locks.
- * As blkcg lock is nested inside q lock, this function performs reverse
- * double lock dancing.
+ * for shooting down all blkgs associated with @css.  blkgs should be
+ * removed while holding both q and blkcg locks.  As blkcg lock is nested
+ * inside q lock, this function performs reverse double lock dancing.
  *
  * This is the blkcg counterpart of ioc_release_fn().
  */
 static void blkcg_css_offline(struct cgroup_subsys_state *css)
 {
         struct blkcg *blkcg = css_to_blkcg(css);
-        struct blkcg_gq *blkg;
 
         spin_lock_irq(&blkcg->lock);
 
-        hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) {
-                struct request_queue *q = blkg->q;
-
-                if (spin_trylock(q->queue_lock)) {
-                        blkg_pd_offline(blkg);
-                        spin_unlock(q->queue_lock);
-                } else {
-                        spin_unlock_irq(&blkcg->lock);
-                        cpu_relax();
-                        spin_lock_irq(&blkcg->lock);
-                }
-        }
-
-        spin_unlock_irq(&blkcg->lock);
-
-        wb_blkcg_offline(blkcg);
-}
-
-/**
- * blkcg_destroy_all_blkgs - destroy all blkgs associated with a blkcg
- * @blkcg: blkcg of interest
- *
- * This function is called when blkcg css is about to free and responsible for
- * destroying all blkgs associated with @blkcg.
- * blkgs should be removed while holding both q and blkcg locks. As blkcg lock
- * is nested inside q lock, this function performs reverse double lock dancing.
- */
-static void blkcg_destroy_all_blkgs(struct blkcg *blkcg)
-{
-        spin_lock_irq(&blkcg->lock);
         while (!hlist_empty(&blkcg->blkg_list)) {
                 struct blkcg_gq *blkg = hlist_entry(blkcg->blkg_list.first,
-                                                    struct blkcg_gq,
-                                                    blkcg_node);
+                                                struct blkcg_gq, blkcg_node);
                 struct request_queue *q = blkg->q;
 
                 if (spin_trylock(q->queue_lock)) {
@@ -1117,7 +1073,10 @@ static void blkcg_destroy_all_blkgs(struct blkcg *blkcg)
                         spin_lock_irq(&blkcg->lock);
                 }
         }
+
         spin_unlock_irq(&blkcg->lock);
+
+        wb_blkcg_offline(blkcg);
 }
 
 static void blkcg_css_free(struct cgroup_subsys_state *css)
@@ -1125,8 +1084,6 @@ static void blkcg_css_free(struct cgroup_subsys_state *css)
         struct blkcg *blkcg = css_to_blkcg(css);
         int i;
 
-        blkcg_destroy_all_blkgs(blkcg);
-
         mutex_lock(&blkcg_pol_mutex);
 
         list_del(&blkcg->all_blkcgs_node);
@@ -1480,11 +1437,8 @@ void blkcg_deactivate_policy(struct request_queue *q,
 
         list_for_each_entry(blkg, &q->blkg_list, q_node) {
                 if (blkg->pd[pol->plid]) {
-                        if (!blkg->pd[pol->plid]->offline &&
-                            pol->pd_offline_fn) {
+                        if (pol->pd_offline_fn)
                                 pol->pd_offline_fn(blkg->pd[pol->plid]);
-                                blkg->pd[pol->plid]->offline = true;
-                        }
                         pol->pd_free_fn(blkg->pd[pol->plid]);
                         blkg->pd[pol->plid] = NULL;
                 }
diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h
index 34aec30e06c7..1615cdd4c797 100644
--- a/include/linux/blk-cgroup.h
+++ b/include/linux/blk-cgroup.h
@@ -89,7 +89,6 @@ struct blkg_policy_data {
         /* the blkg and policy id this per-policy data belongs to */
         struct blkcg_gq                 *blkg;
         int                             plid;
-        bool                            offline;
 };
 
 /*