block: blk_mq_rq_ctx_init cache ctx/q/hctx

We should have enough of registers in blk_mq_rq_ctx_init(), store them
in local vars, so we don't keep reloading them.

note: keeping q->elevator may look unnecessary, but it's also used
inside inlined blk_mq_tags_from_data().

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 1d2e2fd..fa4de25 100644 (file)
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -312,10 +312,14 @@ static inline bool blk_mq_need_time_stamp(struct request *rq)
 static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data,
                unsigned int tag, u64 alloc_time_ns)
 {
+       struct blk_mq_ctx *ctx = data->ctx;
+       struct blk_mq_hw_ctx *hctx = data->hctx;
+       struct request_queue *q = data->q;
+       struct elevator_queue *e = q->elevator;
        struct blk_mq_tags *tags = blk_mq_tags_from_data(data);
        struct request *rq = tags->static_rqs[tag];
 
-       if (data->q->elevator) {
+       if (e) {
                rq->rq_flags = RQF_ELV;
                rq->tag = BLK_MQ_NO_TAG;
                rq->internal_tag = tag;
@@ -330,13 +334,13 @@ static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data,
        else
                rq->start_time_ns = 0;
        /* csd/requeue_work/fifo_time is initialized before use */
-       rq->q = data->q;
-       rq->mq_ctx = data->ctx;
-       rq->mq_hctx = data->hctx;
+       rq->q = q;
+       rq->mq_ctx = ctx;
+       rq->mq_hctx = hctx;
        rq->cmd_flags = data->cmd_flags;
        if (data->flags & BLK_MQ_REQ_PM)
                rq->rq_flags |= RQF_PM;
-       if (blk_queue_io_stat(data->q))
+       if (blk_queue_io_stat(q))
                rq->rq_flags |= RQF_IO_STAT;
        rq->rq_disk = NULL;
        rq->part = NULL;