From 001bea73e70efdf48a9e00188cf302f6b6aed2bf Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Tue, 18 Aug 2015 14:55:11 -0700 Subject: blkcg: replace blkcg_policy->pd_size with ->pd_alloc/free_fn() methods A blkg (blkcg_gq) represents the relationship between a cgroup and request_queue. Each active policy has a pd (blkg_policy_data) on each blkg. The pd's were allocated by blkcg core and each policy could request to allocate extra space at the end by setting blkcg_policy->pd_size larger than the size of pd. This is a bit unusual but was done this way mostly to simplify error handling and all the existing use cases could be handled this way; however, this is becoming too restrictive now that percpu memory can be allocated without blocking. This introduces two new mandatory blkcg_policy methods - pd_alloc_fn() and pd_free_fn() - which are used to allocate and release pd for a given policy. As pd allocation is now done from policy side, it can simply allocate a larger area which embeds pd at the beginning. This change makes ->pd_size pointless. Removed. Signed-off-by: Tejun Heo Cc: Vivek Goyal Signed-off-by: Jens Axboe --- include/linux/blk-cgroup.h | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) (limited to 'include/linux/blk-cgroup.h') diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h index db822880242a..bd173ea360ce 100644 --- a/include/linux/blk-cgroup.h +++ b/include/linux/blk-cgroup.h @@ -68,13 +68,11 @@ struct blkg_rwstat { * request_queue (q). This is used by blkcg policies which need to track * information per blkcg - q pair. * - * There can be multiple active blkcg policies and each has its private - * data on each blkg, the size of which is determined by - * blkcg_policy->pd_size. blkcg core allocates and frees such areas - * together with blkg and invokes pd_init/exit_fn() methods. - * - * Such private data must embed struct blkg_policy_data (pd) at the - * beginning and pd_size can't be smaller than pd. + * There can be multiple active blkcg policies and each blkg:policy pair is + * represented by a blkg_policy_data which is allocated and freed by each + * policy's pd_alloc/free_fn() methods. A policy can allocate private data + * area by allocating larger data structure which embeds blkg_policy_data + * at the beginning. */ struct blkg_policy_data { /* the blkg and policy id this per-policy data belongs to */ @@ -126,16 +124,16 @@ struct blkcg_gq { }; typedef void (blkcg_pol_init_cpd_fn)(const struct blkcg *blkcg); +typedef struct blkg_policy_data *(blkcg_pol_alloc_pd_fn)(gfp_t gfp, int node); typedef void (blkcg_pol_init_pd_fn)(struct blkcg_gq *blkg); typedef void (blkcg_pol_online_pd_fn)(struct blkcg_gq *blkg); typedef void (blkcg_pol_offline_pd_fn)(struct blkcg_gq *blkg); typedef void (blkcg_pol_exit_pd_fn)(struct blkcg_gq *blkg); +typedef void (blkcg_pol_free_pd_fn)(struct blkg_policy_data *pd); typedef void (blkcg_pol_reset_pd_stats_fn)(struct blkcg_gq *blkg); struct blkcg_policy { int plid; - /* policy specific private data size */ - size_t pd_size; /* policy specific per-blkcg data size */ size_t cpd_size; /* cgroup files for the policy */ @@ -143,10 +141,12 @@ struct blkcg_policy { /* operations */ blkcg_pol_init_cpd_fn *cpd_init_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; blkcg_pol_offline_pd_fn *pd_offline_fn; blkcg_pol_exit_pd_fn *pd_exit_fn; + blkcg_pol_free_pd_fn *pd_free_fn; blkcg_pol_reset_pd_stats_fn *pd_reset_stats_fn; }; -- cgit v1.2.1