Commit f4da8072 authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe
Browse files

blkcg: remove blkcg->id 



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: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 55872c5a

block/blk-cgroup.c

+0 −2
Original line number Diff line number Diff line
@@ -822,7 +822,6 @@ static void blkcg_css_free(struct cgroup_subsys_state *css) 
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_state *parent_css) 


	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);

block/blk-cgroup.h

+0 −3
Original line number Diff line number Diff line
@@ -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;

block/cfq-iosched.c

+5 −5
Original line number Diff line number Diff line
@@ -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 cfq_io_cq *cic, struct bio *bio) 
{

	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 cfq_io_cq *cic, struct bio *bio) 
		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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