2021-09-13 15:21:02

by John Garry

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

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 <[email protected]>
---
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);
--
2.26.2

2021-09-14 05:48:22

by Hannes Reinecke

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 <[email protected]>
> ---
> 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 <[email protected]>

Cheers,

Hannes
--
Dr. Hannes Reinecke Kernel Storage Architect
[email protected] +49 911 74053 688
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