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Message-Id: <20240719071506.158075-2-yukuai1@huaweicloud.com>
Date: Fri, 19 Jul 2024 15:15:04 +0800
From: Yu Kuai <yukuai1@...weicloud.com>
To: hch@...radead.org,
bvanassche@....org,
jack@...e.cz,
tj@...nel.org,
josef@...icpanda.com,
axboe@...nel.dk
Cc: cgroups@...r.kernel.org,
linux-block@...r.kernel.org,
linux-kernel@...r.kernel.org,
yukuai3@...wei.com,
yukuai1@...weicloud.com,
yi.zhang@...wei.com,
yangerkun@...wei.com
Subject: [PATCH v3 1/3] blk-cgroup: check for pd_(alloc|free)_fn in blkcg_activate_policy()
From: Yu Kuai <yukuai3@...wei.com>
Currently all policies implement pd_(alloc|free)_fn, however, this is
not necessary for ioprio that only works for blkcg, not blkg.
There are no functional changes, prepare to cleanup activating ioprio
policy.
Signed-off-by: Yu Kuai <yukuai3@...wei.com>
Reviewed-by: Christoph Hellwig <hch@....de>
---
block/blk-cgroup.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 37e6cc91d576..3fa21b941e89 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -1554,6 +1554,14 @@ int blkcg_activate_policy(struct gendisk *disk, const struct blkcg_policy *pol)
if (blkcg_policy_enabled(q, pol))
return 0;
+ /*
+ * Policy is allowed to be registered without pd_alloc_fn/pd_free_fn,
+ * for example, ioprio. Such policy will work on blkcg level, not disk
+ * level, and don't need to be activated.
+ */
+ if (WARN_ON_ONCE(!pol->pd_alloc_fn || !pol->pd_free_fn))
+ return -EINVAL;
+
if (queue_is_mq(q))
blk_mq_freeze_queue(q);
retry:
@@ -1733,9 +1741,12 @@ int blkcg_policy_register(struct blkcg_policy *pol)
goto err_unlock;
}
- /* Make sure cpd/pd_alloc_fn and cpd/pd_free_fn in pairs */
+ /*
+ * Make sure cpd/pd_alloc_fn and cpd/pd_free_fn in pairs, and policy
+ * without pd_alloc_fn/pd_free_fn can't be activated.
+ */
if ((!pol->cpd_alloc_fn ^ !pol->cpd_free_fn) ||
- (!pol->pd_alloc_fn ^ !pol->pd_free_fn))
+ (!pol->pd_alloc_fn ^ !pol->pd_free_fn))
goto err_unlock;
/* register @pol */
--
2.39.2
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