[-next,1/4] blk-iocost: track whether iocg is still online
Commit Message
From: Yu Kuai <yukuai3@huawei.com>
blkcg_gq->online can't be used in iocost because it gets cleared only after
all policies are offlined. This patch add a new field 'online' in iocg.
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
---
block/blk-iocost.c | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
Comments
On Sat, Dec 17, 2022 at 11:05:24AM +0800, Yu Kuai wrote:
> @@ -459,6 +459,8 @@ struct ioc_gq {
> struct blkg_policy_data pd;
> struct ioc *ioc;
>
> + bool online;
Nit: maybe tab align this field like the fields above it.
> +static void ioc_pd_offline(struct blkg_policy_data *pd)
> +{
> + struct ioc_gq *iocg = pd_to_iocg(pd);
> + struct ioc *ioc = iocg->ioc;
> + unsigned long flags;
> +
> + if (ioc) {
How could ioc be NULL here?
Hi, Christoph
在 2022/12/21 18:33, Christoph Hellwig 写道:
> On Sat, Dec 17, 2022 at 11:05:24AM +0800, Yu Kuai wrote:
>> @@ -459,6 +459,8 @@ struct ioc_gq {
>> struct blkg_policy_data pd;
>> struct ioc *ioc;
>>
>> + bool online;
>
> Nit: maybe tab align this field like the fields above it.
>
>> +static void ioc_pd_offline(struct blkg_policy_data *pd)
>> +{
>> + struct ioc_gq *iocg = pd_to_iocg(pd);
>> + struct ioc *ioc = iocg->ioc;
>> + unsigned long flags;
>> +
>> + if (ioc) {
>
> How could ioc be NULL here?
>
As I explained in another thread.. pd_offline_fn() can be called without
pd_init_fn(), which is a bug from upper layer...
blkcg_activate_policy
spin_lock_irq(&q->queue_lock);
list_for_each_entry_reverse(blkg, &q->blkg_list
pd_alloc_fn(GFP_NOWAIT | __GFP_NOWARN,...) -> failed
spin_unlock_irq(&q->queue_lock);
// release queue_lock here is problematic, this will cause
pd_offline_fn called without pd_init_fn.
pd_alloc_fn(__GFP_NOWARN,...)
Thanks,
Kuai
> .
>
@@ -459,6 +459,8 @@ struct ioc_gq {
struct blkg_policy_data pd;
struct ioc *ioc;
+ bool online;
+
/*
* A iocg can get its weight from two sources - an explicit
* per-device-cgroup configuration or the default weight of the
@@ -2952,6 +2954,7 @@ static void ioc_pd_init(struct blkg_policy_data *pd)
ioc_now(ioc, &now);
iocg->ioc = ioc;
+ iocg->online = true;
atomic64_set(&iocg->vtime, now.vnow);
atomic64_set(&iocg->done_vtime, now.vnow);
atomic64_set(&iocg->active_period, atomic64_read(&ioc->cur_period));
@@ -2977,6 +2980,19 @@ static void ioc_pd_init(struct blkg_policy_data *pd)
spin_unlock_irqrestore(&ioc->lock, flags);
}
+static void ioc_pd_offline(struct blkg_policy_data *pd)
+{
+ struct ioc_gq *iocg = pd_to_iocg(pd);
+ struct ioc *ioc = iocg->ioc;
+ unsigned long flags;
+
+ if (ioc) {
+ spin_lock_irqsave(&ioc->lock, flags);
+ iocg->online = false;
+ spin_unlock_irqrestore(&ioc->lock, flags);
+ }
+}
+
static void ioc_pd_free(struct blkg_policy_data *pd)
{
struct ioc_gq *iocg = pd_to_iocg(pd);
@@ -3467,6 +3483,7 @@ static struct blkcg_policy blkcg_policy_iocost = {
.cpd_free_fn = ioc_cpd_free,
.pd_alloc_fn = ioc_pd_alloc,
.pd_init_fn = ioc_pd_init,
+ .pd_offline_fn = ioc_pd_offline,
.pd_free_fn = ioc_pd_free,
.pd_stat_fn = ioc_pd_stat,
};