Commit ce7acfea authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe
Browse files

writeback, blkcg: associate each blkcg_gq with the corresponding bdi_writeback_congested 



A blkg (blkcg_gq) can be congested and decongested independently from
other blkgs on the same request_queue.  Accordingly, for cgroup
writeback support, the congestion status at bdi (backing_dev_info)
should be split and updated separately from matching blkg's.

This patch prepares by adding blkg->wb_congested and associating a
blkg with its matching per-blkcg bdi_writeback_congested on creation.

v2: Updated to associate bdi_writeback_congested instead of
    bdi_writeback.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jan Kara <jack@suse.cz>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 52ebea74

block/blk-cgroup.c

+15 −2
Original line number Diff line number Diff line
@@ -182,6 +182,7 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg, 
				    struct blkcg_gq *new_blkg)

{

	struct blkcg_gq *blkg;

	struct bdi_writeback_congested *wb_congested;

	int i, ret;



	WARN_ON_ONCE(!rcu_read_lock_held());
@@ -193,22 +194,30 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg, 
		goto err_free_blkg;

	}



	wb_congested = wb_congested_get_create(&q->backing_dev_info,

					       blkcg->css.id, GFP_ATOMIC);

	if (!wb_congested) {

		ret = -ENOMEM;

		goto err_put_css;

	}



	/* allocate */

	if (!new_blkg) {

		new_blkg = blkg_alloc(blkcg, q, GFP_ATOMIC);

		if (unlikely(!new_blkg)) {

			ret = -ENOMEM;

			goto err_put_css;

			goto err_put_congested;

		}

	}

	blkg = new_blkg;

	blkg->wb_congested = wb_congested;



	/* link parent */

	if (blkcg_parent(blkcg)) {

		blkg->parent = __blkg_lookup(blkcg_parent(blkcg), q, false);

		if (WARN_ON_ONCE(!blkg->parent)) {

			ret = -EINVAL;

			goto err_put_css;

			goto err_put_congested;

		}

		blkg_get(blkg->parent);

	}
@@ -245,6 +254,8 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg, 
	blkg_put(blkg);

	return ERR_PTR(ret);



err_put_congested:

	wb_congested_put(wb_congested);

err_put_css:

	css_put(&blkcg->css);

err_free_blkg:
@@ -391,6 +402,8 @@ void __blkg_release_rcu(struct rcu_head *rcu_head) 
	if (blkg->parent)

		blkg_put(blkg->parent);



	wb_congested_put(blkg->wb_congested);



	blkg_free(blkg);

}

EXPORT_SYMBOL_GPL(__blkg_release_rcu);

include/linux/blk-cgroup.h

+6 −0
Original line number Diff line number Diff line
@@ -99,6 +99,12 @@ struct blkcg_gq { 
	struct hlist_node		blkcg_node;

	struct blkcg			*blkcg;



	/*

	 * Each blkg gets congested separately and the congestion state is

	 * propagated to the matching bdi_writeback_congested.

	 */

	struct bdi_writeback_congested	*wb_congested;



	/* all non-root blkcg_gq's are guaranteed to have access to parent */

	struct blkcg_gq			*parent;

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