block: inherit CPU completion on bio->rq and rq->rq merges

Somewhat incomplete, as we do allow merges of requests and bios
that have different completion CPUs given. This is done on the
assumption that a larger IO is still more beneficial than CPU
locality.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/block/blk-merge.c b/block/blk-merge.c
index c77196d55899..908d3e11ac52 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -400,6 +400,8 @@ static int attempt_merge(struct request_queue *q, struct request *req,
         }
 
         req->ioprio = ioprio_best(req->ioprio, next->ioprio);
+        if (blk_rq_cpu_valid(next))
+                req->cpu = next->cpu;
 
         __blk_put_request(q, next);
         return 1;