Re: [PATCH v5 01/12] blk-mq: pass correct hctx to blk_mq_try_issue_directly

[Bart Van Assche]

On Tue, 2017-06-06 at 23:21 +0800, Ming Lei wrote:
> When direct issue is done on request picked up from plug list,
> the hctx need to be updated with the actual hw queue, otherwise
> wrong hctx is used and may hurt performance, especially when
> wrong SRCU readlock is acquired/released

Reviewed-by: Bart Van Assche 

[PATCH v5 01/12] blk-mq: pass correct hctx to blk_mq_try_issue_directly

[Ming Lei]

When direct issue is done on request picked up from plug list,
the hctx need to be updated with the actual hw queue, otherwise
wrong hctx is used and may hurt performance, especially when
wrong SRCU readlock is acquired/released

Reported-by: Bart Van Assche 
Signed-off-by: Ming Lei 
---
 block/blk-mq.c | 5 -
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 58688205c8f4..c13888922e18 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1558,9 +1558,12 @@ static blk_qc_t blk_mq_make_request(struct request_queue 
*q, struct bio *bio)
 
blk_mq_put_ctx(data.ctx);
 
-   if (same_queue_rq)
+   if (same_queue_rq) {
+   data.hctx = blk_mq_map_queue(q,
+   same_queue_rq->mq_ctx->cpu);
blk_mq_try_issue_directly(data.hctx, same_queue_rq,
);
+   }
} else if (q->nr_hw_queues > 1 && is_sync) {
blk_mq_put_ctx(data.ctx);
blk_mq_bio_to_request(rq, bio);
-- 
2.9.4