On Mon, Sep 08, 2014 at 08:15:20AM +0900, Tejun Heo wrote:
> blkcg->id is a unique id given to each blkcg; however, the
> cgroup_subsys_state which each blkcg embeds already has ->serial_nr
> which can be used for the same purpose. Drop blkcg->id and replace
> its uses with blkcg->css.serial_nr. Rename cfq_cgroup->blkcg_id to
> ->blkcg_serial_nr and @id in check_blkcg_changed() to @serial_nr for
> consistency.
>
> Signed-off-by: Tejun Heo <t...@kernel.org>
> Cc: Vivek Goyal <vgo...@redhat.com>
Looks good to me.
Acked-by: Vivek Goyal <vgo...@redhat.com>
Vivek
> ---
> block/blk-cgroup.c | 2 --
> block/blk-cgroup.h | 3 ---
> block/cfq-iosched.c | 10 +++++-----
> 3 files changed, 5 insertions(+), 10 deletions(-)
>
> --- a/block/blk-cgroup.c
> +++ b/block/blk-cgroup.c
> @@ -822,7 +822,6 @@ static void blkcg_css_free(struct cgroup
> static struct cgroup_subsys_state *
> blkcg_css_alloc(struct cgroup_subsys_state *parent_css)
> {
> - static atomic64_t id_seq = ATOMIC64_INIT(0);
> struct blkcg *blkcg;
>
> if (!parent_css) {
> @@ -836,7 +835,6 @@ blkcg_css_alloc(struct cgroup_subsys_sta
>
> blkcg->cfq_weight = CFQ_WEIGHT_DEFAULT;
> blkcg->cfq_leaf_weight = CFQ_WEIGHT_DEFAULT;
> - blkcg->id = atomic64_inc_return(&id_seq); /* root is 0, start from 1 */
> done:
> spin_lock_init(&blkcg->lock);
> INIT_RADIX_TREE(&blkcg->blkg_tree, GFP_ATOMIC);
> --- a/block/blk-cgroup.h
> +++ b/block/blk-cgroup.h
> @@ -50,9 +50,6 @@ struct blkcg {
> struct blkcg_gq *blkg_hint;
> struct hlist_head blkg_list;
>
> - /* for policies to test whether associated blkcg has changed */
> - uint64_t id;
> -
> /* TODO: per-policy storage in blkcg */
> unsigned int cfq_weight; /* belongs to cfq */
> unsigned int cfq_leaf_weight;
> --- a/block/cfq-iosched.c
> +++ b/block/cfq-iosched.c
> @@ -299,7 +299,7 @@ struct cfq_io_cq {
> struct cfq_ttime ttime;
> int ioprio; /* the current ioprio */
> #ifdef CONFIG_CFQ_GROUP_IOSCHED
> - uint64_t blkcg_id; /* the current blkcg ID */
> + uint64_t blkcg_serial_nr; /* the current blkcg serial */
> #endif
> };
>
> @@ -3534,17 +3534,17 @@ static void check_blkcg_changed(struct c
> {
> struct cfq_data *cfqd = cic_to_cfqd(cic);
> struct cfq_queue *sync_cfqq;
> - uint64_t id;
> + uint64_t serial_nr;
>
> rcu_read_lock();
> - id = bio_blkcg(bio)->id;
> + serial_nr = bio_blkcg(bio)->css.serial_nr;
> rcu_read_unlock();
>
> /*
> * Check whether blkcg has changed. The condition may trigger
> * spuriously on a newly created cic but there's no harm.
> */
> - if (unlikely(!cfqd) || likely(cic->blkcg_id == id))
> + if (unlikely(!cfqd) || likely(cic->blkcg_serial_nr == serial_nr))
> return;
>
> sync_cfqq = cic_to_cfqq(cic, 1);
> @@ -3558,7 +3558,7 @@ static void check_blkcg_changed(struct c
> cfq_put_queue(sync_cfqq);
> }
>
> - cic->blkcg_id = id;
> + cic->blkcg_serial_nr = serial_nr;
> }
> #else
> static inline void check_blkcg_changed(struct cfq_io_cq *cic, struct bio
> *bio) { }
--
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