blk-mq: initialize req->q in allocation

The patch basically reverts the patch of(blk-mq:
initialize request on allocation) in Jens's tree(already
in -next), and only initialize req->q in allocation
for two reasons:

	- presumed cache hotness on completion
	- blk_rq_tagged(rq) depends on reset of req->mq_ctx

Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 3a560a4db0b4047f1d5c295208aaeb02fb69b328..c26b3be1893c67748ce4a587a640191b31c08646 100644 (file)
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -82,7 +82,6 @@ static struct request *__blk_mq_alloc_request(struct blk_mq_hw_ctx *hctx,
        tag = blk_mq_get_tag(hctx->tags, gfp, reserved);
        if (tag != BLK_MQ_TAG_FAIL) {
                rq = hctx->tags->rqs[tag];
-               blk_rq_init(hctx->queue, rq);
                rq->tag = tag;
 
                return rq;
@@ -187,6 +186,7 @@ static void blk_mq_rq_ctx_init(struct request_queue *q, struct blk_mq_ctx *ctx,
        if (blk_queue_io_stat(q))
                rw_flags |= REQ_IO_STAT;
 
+       rq->q = q;
        rq->mq_ctx = ctx;
        rq->cmd_flags = rw_flags;
        rq->start_time = jiffies;
@@ -258,6 +258,7 @@ static void __blk_mq_free_request(struct blk_mq_hw_ctx *hctx,
        const int tag = rq->tag;
        struct request_queue *q = rq->q;
 
+       blk_rq_init(hctx->queue, rq);
        blk_mq_put_tag(hctx->tags, tag);
        blk_mq_queue_exit(q);
 }
@@ -1194,6 +1195,7 @@ static struct blk_mq_tags *blk_mq_init_rq_map(struct blk_mq_tag_set *set,
                left -= to_do * rq_size;
                for (j = 0; j < to_do; j++) {
                        tags->rqs[i] = p;
+                       blk_rq_init(NULL, tags->rqs[i]);
                        if (set->ops->init_request) {
                                if (set->ops->init_request(set->driver_data,
                                                tags->rqs[i], hctx_idx, i,