blkcg: replace blkcg_policy->cpd_size with ->cpd_alloc/free_fn() methods

[linux-2.6-block.git] / include / linux / blk-cgroup.h

diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h
index 7988d4749fffb094032c8a6aaedcdd2c003e433b..15f2382bc723819ad8374516913fb2110d5a9128 100644 (file)
--- a/include/linux/blk-cgroup.h
+++ b/include/linux/blk-cgroup.h
@@ -81,11 +81,11 @@ struct blkg_policy_data {
 };
 
 /*
- * Policies that need to keep per-blkcg data which is independent
- * from any request_queue associated to it must specify its size
- * with the cpd_size field of the blkcg_policy structure and
- * embed a blkcg_policy_data in it.  cpd_init() is invoked to let
- * each policy handle per-blkcg data.
+ * Policies that need to keep per-blkcg data which is independent from any
+ * request_queue associated to it should implement cpd_alloc/free_fn()
+ * methods.  A policy can allocate private data area by allocating larger
+ * data structure which embeds blkcg_policy_data at the beginning.
+ * cpd_init() is invoked to let each policy handle per-blkcg data.
  */
 struct blkcg_policy_data {
        /* the blkcg and policy id this per-policy data belongs to */
@@ -124,7 +124,9 @@ struct blkcg_gq {
        struct rcu_head                 rcu_head;
 };
 
+typedef struct blkcg_policy_data *(blkcg_pol_alloc_cpd_fn)(gfp_t gfp);
 typedef void (blkcg_pol_init_cpd_fn)(struct blkcg_policy_data *cpd);
+typedef void (blkcg_pol_free_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);
@@ -134,13 +136,14 @@ typedef void (blkcg_pol_reset_pd_stats_fn)(struct blkg_policy_data *pd);
 
 struct blkcg_policy {
        int                             plid;
-       /* policy specific per-blkcg data size */
-       size_t                          cpd_size;
        /* cgroup files for the policy */
        struct cftype                   *cftypes;
 
        /* operations */
+       blkcg_pol_alloc_cpd_fn          *cpd_alloc_fn;
        blkcg_pol_init_cpd_fn           *cpd_init_fn;
+       blkcg_pol_free_cpd_fn           *cpd_free_fn;
+
        blkcg_pol_alloc_pd_fn           *pd_alloc_fn;
        blkcg_pol_init_pd_fn            *pd_init_fn;
        blkcg_pol_online_pd_fn          *pd_online_fn;