blk-mq: Remove blk_mq_queue_data.list

The block layer core sets blk_mq_queue_data.list but no block
drivers read that member. Hence remove it and also the code that
is used to set this member.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Jens Axboe <axboe@fb.com>

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 061fc2c..f7cd320 100644 (file)
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -984,17 +984,9 @@ bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list)
 {
        struct request_queue *q = hctx->queue;
        struct request *rq;
-       LIST_HEAD(driver_list);
-       struct list_head *dptr;
        int errors, queued, ret = BLK_MQ_RQ_QUEUE_OK;
 
        /*
-        * Start off with dptr being NULL, so we start the first request
-        * immediately, even if we have more pending.
-        */
-       dptr = NULL;
-
-       /*
         * Now process all the entries, sending them to the driver.
         */
        errors = queued = 0;
@@ -1026,7 +1018,6 @@ bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list)
                list_del_init(&rq->queuelist);
 
                bd.rq = rq;
-               bd.list = dptr;
 
                /*
                 * Flag last if we have no more requests, or if we have more
@@ -1062,13 +1053,6 @@ bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list)
 
                if (ret == BLK_MQ_RQ_QUEUE_BUSY)
                        break;
-
-               /*
-                * We've done the first request. If we have more than 1
-                * left in the list, set dptr to defer issue.
-                */
-               if (!dptr && list->next != list->prev)
-                       dptr = &driver_list;
        }
 
        hctx->dispatched[queued_to_index(queued)]++;
@@ -1451,7 +1435,6 @@ static void __blk_mq_try_issue_directly(struct request *rq, blk_qc_t *cookie,
        struct request_queue *q = rq->q;
        struct blk_mq_queue_data bd = {
                .rq = rq,
-               .list = NULL,
                .last = 1
        };
        struct blk_mq_hw_ctx *hctx;

diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index ea2e9dc..bdea90d 100644 (file)
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -81,7 +81,6 @@ struct blk_mq_tag_set {
 
 struct blk_mq_queue_data {
        struct request *rq;
-       struct list_head *list;
        bool last;
 };