blk-mq: check on cpu id when there is only one ctx mapping

commit f168420 ("blk-mq: don't redirect completion for hctx withs
only one ctx mapping") When nvme applies a 1:1 mapping of hctx and ctx,
there will be no remote request.

But for ufs, the submission and completion queues could be asymmetric.
(e.g. Multiple SQs share one CQ) Therefore, 1:1 mapping of hctx and
ctx won't complete request on the submission cpu. In this situation,
this nr_ctx check could violate the QUEUE_FLAG_SAME_FORCE, as a result,
check on cpu id when there is only one ctx mapping.

Signed-off-by: Ed Tsai <[email protected]>
Signed-off-by: Po-Wen Kao <[email protected]>
Suggested-by: Keith Busch <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
[axboe: fixed up indentation]
Signed-off-by: Jens Axboe <[email protected]>

Author: Ed Tsai

block/blk-mq.c

@@ -1185,8 +1185,9 @@ bool blk_mq_complete_request_remote(struct request *rq)
 	 * or a polled request, always complete locally,
 	 * it's pointless to redirect the completion.
 	 */
-	if (rq->mq_hctx->nr_ctx == 1 ||
-		rq->cmd_flags & REQ_POLLED)
+	if ((rq->mq_hctx->nr_ctx == 1 &&
+	     rq->mq_ctx->cpu == raw_smp_processor_id()) ||
+	     rq->cmd_flags & REQ_POLLED)
 		return false;
 
 	if (blk_mq_complete_need_ipi(rq)) {