block: avoid to use q->flush_rq directly

This patch trys to use local variable to access flush request,
so that we can convert to per-queue flush machinery a bit easier.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

diff --git a/block/blk-flush.c b/block/blk-flush.c
index a49ffbd..caf4475 100644 (file)
--- a/block/blk-flush.c
+++ b/block/blk-flush.c
@@ -223,7 +223,7 @@ static void flush_end_io(struct request *flush_rq, int error)
 
        if (q->mq_ops) {
                spin_lock_irqsave(&q->mq_flush_lock, flags);
-               q->flush_rq->tag = -1;
+               flush_rq->tag = -1;
        }
 
        running = &q->flush_queue[q->flush_running_idx];
@@ -281,6 +281,7 @@ static bool blk_kick_flush(struct request_queue *q)
        struct list_head *pending = &q->flush_queue[q->flush_pending_idx];
        struct request *first_rq =
                list_first_entry(pending, struct request, flush.list);
+       struct request *flush_rq = q->flush_rq;
 
        /* C1 described at the top of this file */
        if (q->flush_pending_idx != q->flush_running_idx || list_empty(pending))
@@ -298,16 +299,16 @@ static bool blk_kick_flush(struct request_queue *q)
         */
        q->flush_pending_idx ^= 1;
 
-       blk_rq_init(q, q->flush_rq);
+       blk_rq_init(q, flush_rq);
        if (q->mq_ops)
-               blk_mq_clone_flush_request(q->flush_rq, first_rq);
+               blk_mq_clone_flush_request(flush_rq, first_rq);
 
-       q->flush_rq->cmd_type = REQ_TYPE_FS;
-       q->flush_rq->cmd_flags = WRITE_FLUSH | REQ_FLUSH_SEQ;
-       q->flush_rq->rq_disk = first_rq->rq_disk;
-       q->flush_rq->end_io = flush_end_io;
+       flush_rq->cmd_type = REQ_TYPE_FS;
+       flush_rq->cmd_flags = WRITE_FLUSH | REQ_FLUSH_SEQ;
+       flush_rq->rq_disk = first_rq->rq_disk;
+       flush_rq->end_io = flush_end_io;
 
-       return blk_flush_queue_rq(q->flush_rq, false);
+       return blk_flush_queue_rq(flush_rq, false);
 }
 
 static void flush_data_end_io(struct request *rq, int error)