linux-kernel - Re: [PATCH RESEND v3 08/13] blk-mq: Don't clear driver tags own mapping

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Message-ID: <e489b220-b01d-4408-c166-e23c9d96d43a@suse.de>
Date:   Tue, 14 Sep 2021 07:45:50 +0200
From:   Hannes Reinecke <hare@...e.de>
To:     John Garry <john.garry@...wei.com>, axboe@...nel.dk
Cc:     linux-kernel@...r.kernel.org, linux-block@...r.kernel.org,
        ming.lei@...hat.com, linux-scsi@...r.kernel.org
Subject: Re: [PATCH RESEND v3 08/13] blk-mq: Don't clear driver tags own
 mapping

On 9/13/21 5:12 PM, John Garry wrote:
> Function blk_mq_clear_rq_mapping() is required to clear the sched tags
> mappings in driver tags rqs[].
> 
> But there is no need for a driver tags to clear its own mapping, so skip
> clearing the mapping in this scenario.
> 
> Signed-off-by: John Garry <john.garry@...wei.com>
> ---
>   block/blk-mq.c | 4 ++++
>   1 file changed, 4 insertions(+)
> 
> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index 4bae8afdfbe1..5229c5420b85 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -2308,6 +2308,10 @@ static void blk_mq_clear_rq_mapping(struct blk_mq_tags *drv_tags,
>   	struct page *page;
>   	unsigned long flags;
>   
> +	/* There is no need to clear a driver tags own mapping */
> +	if (drv_tags == tags)
> +		return;
> +
>   	list_for_each_entry(page, &tags->page_list, lru) {
>   		unsigned long start = (unsigned long)page_address(page);
>   		unsigned long end = start + order_to_size(page->private);
> 
Reviewed-by: Hannes Reinecke <hare@...e.de>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                Kernel Storage Architect
hare@...e.de                              +49 911 74053 688
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