linux-kernel - Re: [PATCH v7 1/2] blk-throtl: introduce a new flag THROTL_TG

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Message-ID: <6167d87a-bb4a-5323-9918-8ff46126ed13@huawei.com>
Date:   Tue, 8 Feb 2022 11:54:22 +0800
From:   "yukuai (C)" <yukuai3@...wei.com>
To:     Ming Lei <ming.lei@...hat.com>
CC:     <tj@...nel.org>, <axboe@...nel.dk>, <cgroups@...r.kernel.org>,
        <linux-block@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <yi.zhang@...wei.com>
Subject: Re: [PATCH v7 1/2] blk-throtl: introduce a new flag
 THROTL_TG_CANCELING

在 2022/02/07 16:15, Ming Lei 写道:
> On Fri, Jan 28, 2022 at 04:45:21PM +0800, Yu Kuai wrote:
>> If the new flag is set, then the throtl_grp will stop throttling bios.
>> Prepare to canceling all throttled bios if the disk is gone.
>>
>> Signed-off-by: Yu Kuai <yukuai3@...wei.com>
>> ---
>>   block/blk-throttle.c | 17 +++++++++++++----
>>   1 file changed, 13 insertions(+), 4 deletions(-)
>>
>> diff --git a/block/blk-throttle.c b/block/blk-throttle.c
>> index 7c462c006b26..abc5e506c72d 100644
>> --- a/block/blk-throttle.c
>> +++ b/block/blk-throttle.c
>> @@ -43,8 +43,12 @@
>>   static struct workqueue_struct *kthrotld_workqueue;
>>   
>>   enum tg_state_flags {
>> -	THROTL_TG_PENDING	= 1 << 0,	/* on parent's pending tree */
>> -	THROTL_TG_WAS_EMPTY	= 1 << 1,	/* bio_lists[] became non-empty */
>> +	/* on parent's pending tree */
>> +	THROTL_TG_PENDING	= 1 << 0,
>> +	/* bio_lists[] became non-empty */
>> +	THROTL_TG_WAS_EMPTY	= 1 << 1,
>> +	/* starts to cancel all bios, will be set if the disk is deleted */
>> +	THROTL_TG_CANCELING	= 1 << 2,
>>   };
>>   
>>   #define rb_entry_tg(node)	rb_entry((node), struct throtl_grp, rb_node)
>> @@ -871,7 +875,8 @@ static bool tg_may_dispatch(struct throtl_grp *tg, struct bio *bio,
>>   	       bio != throtl_peek_queued(&tg->service_queue.queued[rw]));
>>   
>>   	/* If tg->bps = -1, then BW is unlimited */
>> -	if (bps_limit == U64_MAX && iops_limit == UINT_MAX) {
>> +	if ((bps_limit == U64_MAX && iops_limit == UINT_MAX) ||
>> +	    tg->flags & THROTL_TG_CANCELING) {
>>   		if (wait)
>>   			*wait = 0;
>>   		return true;
>> @@ -974,6 +979,9 @@ static void tg_update_disptime(struct throtl_grp *tg)
>>   	unsigned long read_wait = -1, write_wait = -1, min_wait = -1, disptime;
>>   	struct bio *bio;
>>   
>> +	if (tg->flags & THROTL_TG_CANCELING)
>> +		goto update;
>> +
> 
> The above change and the following one in tg_update_disptime() isn't
> needed actually.
> 
> Also I'd suggest to fold the two into one patch.

Ok, I'll fold the two in next version.

Thanks,
Kuai
> 
> 
> Thanks,
> Ming
> 
> .
>