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: Tejun 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: Jens Axboe <axboe@fb.com>
This commit is contained in:
@@ -182,6 +182,7 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg,
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struct blkcg_gq *new_blkg)
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{
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struct blkcg_gq *blkg;
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struct bdi_writeback_congested *wb_congested;
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int i, ret;
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WARN_ON_ONCE(!rcu_read_lock_held());
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@@ -193,22 +194,30 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg,
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goto err_free_blkg;
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}
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wb_congested = wb_congested_get_create(&q->backing_dev_info,
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blkcg->css.id, GFP_ATOMIC);
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if (!wb_congested) {
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ret = -ENOMEM;
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goto err_put_css;
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}
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/* allocate */
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if (!new_blkg) {
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new_blkg = blkg_alloc(blkcg, q, GFP_ATOMIC);
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if (unlikely(!new_blkg)) {
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ret = -ENOMEM;
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goto err_put_css;
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goto err_put_congested;
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}
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}
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blkg = new_blkg;
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blkg->wb_congested = wb_congested;
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/* link parent */
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if (blkcg_parent(blkcg)) {
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blkg->parent = __blkg_lookup(blkcg_parent(blkcg), q, false);
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if (WARN_ON_ONCE(!blkg->parent)) {
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ret = -EINVAL;
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goto err_put_css;
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goto err_put_congested;
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}
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blkg_get(blkg->parent);
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}
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@@ -245,6 +254,8 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg,
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blkg_put(blkg);
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return ERR_PTR(ret);
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err_put_congested:
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wb_congested_put(wb_congested);
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err_put_css:
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css_put(&blkcg->css);
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err_free_blkg:
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@@ -391,6 +402,8 @@ void __blkg_release_rcu(struct rcu_head *rcu_head)
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if (blkg->parent)
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blkg_put(blkg->parent);
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wb_congested_put(blkg->wb_congested);
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blkg_free(blkg);
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}
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EXPORT_SYMBOL_GPL(__blkg_release_rcu);
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