# \[PATCH v5 08/14\] blk-mq: Don't clear driver tags own mapping

- From: John Garry \<hidden\>
- Date: 2021-10-05 10:29:28 
- List: linux-block
- Page: https://ratatoskr.run/linux-block/2021/10/1531240
- Thread: https://ratatoskr.run/linux-block/2021/10/1531231/t.md

```text
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 <redacted>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Ming Lei <redacted>
---
 block/blk-mq.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 1bee153e6b7f..158ee7dbbd76 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2310,6 +2310,10 @@ 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

```