blkcg: minor updates around blkcg_policy_data

* Rename blkcg->pd[] to blkcg->cpd[] so that cpd is consistently used
  for blkcg_policy_data.

* Make blkcg_policy->cpd_init_fn() take blkcg_policy_data instead of
  blkcg.  This makes it consistent with blkg_policy_data methods and
  to-be-added cpd alloc/free methods.

* blkcg_policy_data->blkcg and cpd_to_blkcg() added so that
  cpd_init_fn() can determine the associated blkcg from
  blkcg_policy_data.

v2: blkcg_policy_data->blkcg initializations were missing.  Added.

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

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 8343450cffe26fcdd8099cda2615f866fc7f193a..247c42c8c83be5650dc1e0662a37597024da0c05 100644 (file)
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -821,7 +821,7 @@ static void blkcg_css_free(struct cgroup_subsys_state *css)
        mutex_unlock(&blkcg_pol_mutex);
 
        for (i = 0; i < BLKCG_MAX_POLS; i++)
-               kfree(blkcg->pd[i]);
+               kfree(blkcg->cpd[i]);
        kfree(blkcg);
 }
 
@@ -857,15 +857,16 @@ blkcg_css_alloc(struct cgroup_subsys_state *parent_css)
                if (!pol || !pol->cpd_size)
                        continue;
 
-               BUG_ON(blkcg->pd[i]);
+               BUG_ON(blkcg->cpd[i]);
                cpd = kzalloc(pol->cpd_size, GFP_KERNEL);
                if (!cpd) {
                        ret = ERR_PTR(-ENOMEM);
                        goto free_pd_blkcg;
                }
-               blkcg->pd[i] = cpd;
+               blkcg->cpd[i] = cpd;
+               cpd->blkcg = blkcg;
                cpd->plid = i;
-               pol->cpd_init_fn(blkcg);
+               pol->cpd_init_fn(cpd);
        }
 
        spin_lock_init(&blkcg->lock);
@@ -881,7 +882,7 @@ blkcg_css_alloc(struct cgroup_subsys_state *parent_css)
 
 free_pd_blkcg:
        for (i--; i >= 0; i--)
-               kfree(blkcg->pd[i]);
+               kfree(blkcg->cpd[i]);
 free_blkcg:
        kfree(blkcg);
        mutex_unlock(&blkcg_pol_mutex);
@@ -1168,9 +1169,10 @@ int blkcg_policy_register(struct blkcg_policy *pol)
                                goto err_free_cpds;
                        }
 
-                       blkcg->pd[pol->plid] = cpd;
+                       blkcg->cpd[pol->plid] = cpd;
+                       cpd->blkcg = blkcg;
                        cpd->plid = pol->plid;
-                       pol->cpd_init_fn(blkcg);
+                       pol->cpd_init_fn(cpd);
                }
        }
 
@@ -1186,8 +1188,8 @@ int blkcg_policy_register(struct blkcg_policy *pol)
 err_free_cpds:
        if (pol->cpd_size) {
                list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) {
-                       kfree(blkcg->pd[pol->plid]);
-                       blkcg->pd[pol->plid] = NULL;
+                       kfree(blkcg->cpd[pol->plid]);
+                       blkcg->cpd[pol->plid] = NULL;
                }
        }
        blkcg_policy[pol->plid] = NULL;
@@ -1222,8 +1224,8 @@ void blkcg_policy_unregister(struct blkcg_policy *pol)
 
        if (pol->cpd_size) {
                list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) {
-                       kfree(blkcg->pd[pol->plid]);
-                       blkcg->pd[pol->plid] = NULL;
+                       kfree(blkcg->cpd[pol->plid]);
+                       blkcg->cpd[pol->plid] = NULL;
                }
        }
        blkcg_policy[pol->plid] = NULL;

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 95e6b0cbaa84ff818323bf144bcc780c79d8c003..dd6ea9ee624565e1036178dcf1b84c5149e6ee6e 100644 (file)
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -220,7 +220,7 @@ struct cfqg_stats {
 /* Per-cgroup data */
 struct cfq_group_data {
        /* must be the first member */
-       struct blkcg_policy_data pd;
+       struct blkcg_policy_data cpd;
 
        unsigned int weight;
        unsigned int leaf_weight;
@@ -612,7 +612,7 @@ static inline struct cfq_group *pd_to_cfqg(struct blkg_policy_data *pd)
 static struct cfq_group_data
 *cpd_to_cfqgd(struct blkcg_policy_data *cpd)
 {
-       return cpd ? container_of(cpd, struct cfq_group_data, pd) : NULL;
+       return cpd ? container_of(cpd, struct cfq_group_data, cpd) : NULL;
 }
 
 static inline struct blkcg_gq *cfqg_to_blkg(struct cfq_group *cfqg)
@@ -1568,12 +1568,11 @@ static void cfqg_stats_init(struct cfqg_stats *stats)
 #endif
 }
 
-static void cfq_cpd_init(const struct blkcg *blkcg)
+static void cfq_cpd_init(struct blkcg_policy_data *cpd)
 {
-       struct cfq_group_data *cgd =
-               cpd_to_cfqgd(blkcg->pd[blkcg_policy_cfq.plid]);
+       struct cfq_group_data *cgd = cpd_to_cfqgd(cpd);
 
-       if (blkcg == &blkcg_root) {
+       if (cpd_to_blkcg(cpd) == &blkcg_root) {
                cgd->weight = 2 * CFQ_WEIGHT_DEFAULT;
                cgd->leaf_weight = 2 * CFQ_WEIGHT_DEFAULT;
        } else {

diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h
index ddd4b8b252c77e790f1f1b3afa1b1f4686fedd46..7988d4749fffb094032c8a6aaedcdd2c003e433b 100644 (file)
--- a/include/linux/blk-cgroup.h
+++ b/include/linux/blk-cgroup.h
@@ -45,7 +45,7 @@ struct blkcg {
        struct blkcg_gq                 *blkg_hint;
        struct hlist_head               blkg_list;
 
-       struct blkcg_policy_data        *pd[BLKCG_MAX_POLS];
+       struct blkcg_policy_data        *cpd[BLKCG_MAX_POLS];
 
        struct list_head                all_blkcgs_node;
 #ifdef CONFIG_CGROUP_WRITEBACK
@@ -88,7 +88,8 @@ struct blkg_policy_data {
  * each policy handle per-blkcg data.
  */
 struct blkcg_policy_data {
-       /* the policy id this per-policy data belongs to */
+       /* the blkcg and policy id this per-policy data belongs to */
+       struct blkcg                    *blkcg;
        int                             plid;
 };
 
@@ -123,7 +124,7 @@ struct blkcg_gq {
        struct rcu_head                 rcu_head;
 };
 
-typedef void (blkcg_pol_init_cpd_fn)(const struct blkcg *blkcg);
+typedef void (blkcg_pol_init_cpd_fn)(struct blkcg_policy_data *cpd);
 typedef struct blkg_policy_data *(blkcg_pol_alloc_pd_fn)(gfp_t gfp, int node);
 typedef void (blkcg_pol_init_pd_fn)(struct blkg_policy_data *pd);
 typedef void (blkcg_pol_online_pd_fn)(struct blkg_policy_data *pd);
@@ -243,7 +244,7 @@ static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
 static inline struct blkcg_policy_data *blkcg_to_cpd(struct blkcg *blkcg,
                                                     struct blkcg_policy *pol)
 {
-       return blkcg ? blkcg->pd[pol->plid] : NULL;
+       return blkcg ? blkcg->cpd[pol->plid] : NULL;
 }
 
 /**
@@ -257,6 +258,11 @@ static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd)
        return pd ? pd->blkg : NULL;
 }
 
+static inline struct blkcg *cpd_to_blkcg(struct blkcg_policy_data *cpd)
+{
+       return cpd ? cpd->blkcg : NULL;
+}
+
 /**
  * blkg_path - format cgroup path of blkg
  * @blkg: blkg of interest