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blk-cgroup: check for pd_(alloc|free)_fn in blkcg_activate_policy()

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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@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20240719071506.158075-2-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Yu Kuai 2024-07-19 15:15:04 +08:00 committed by Jens Axboe
parent 8400291e28
commit ae8650b45d
1 changed files with 13 additions and 2 deletions
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15
block/blk-cgroup.c
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@ -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 */