blk-mq: do not initialize req->special

Drivers can reach their private data easily using the blk_mq_rq_to_pdu
helper and don't need req->special.  By not initializing it code can
be simplified nicely, and we also shave off a few more instructions from
the I/O path.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>

diff --git a/block/blk-flush.c b/block/blk-flush.c
index 77f20458910c219f322a9f5ad3d4492a7bd99f2d..0e42adcfb55e26ea9a669a5ed6924cc5661123f8 100644 (file)
--- a/block/blk-flush.c
+++ b/block/blk-flush.c
@@ -306,22 +306,16 @@ static bool blk_kick_flush(struct request_queue *q)
         */
        q->flush_pending_idx ^= 1;
 
+       blk_rq_init(q, q->flush_rq);
        if (q->mq_ops) {
-               struct blk_mq_ctx *ctx = first_rq->mq_ctx;
-               struct blk_mq_hw_ctx *hctx = q->mq_ops->map_queue(q, ctx->cpu);
-
-               blk_mq_rq_init(hctx, q->flush_rq);
-               q->flush_rq->mq_ctx = ctx;
-
                /*
                 * Reuse the tag value from the fist waiting request,
                 * with blk-mq the tag is generated during request
                 * allocation and drivers can rely on it being inside
                 * the range they asked for.
                 */
+               q->flush_rq->mq_ctx = first_rq->mq_ctx;
                q->flush_rq->tag = first_rq->tag;
-       } else {
-               blk_rq_init(q, q->flush_rq);
        }
 
        q->flush_rq->cmd_type = REQ_TYPE_FS;

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 658428a28fafb47e3644c100f320addaf1d62e26..d9d0984d2f01095977f824540a1686ee36f8fc77 100644 (file)
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -251,24 +251,13 @@ struct request *blk_mq_alloc_reserved_request(struct request_queue *q, int rw,
 }
 EXPORT_SYMBOL(blk_mq_alloc_reserved_request);
 
-/*
- * Re-init and set pdu, if we have it
- */
-void blk_mq_rq_init(struct blk_mq_hw_ctx *hctx, struct request *rq)
-{
-       blk_rq_init(hctx->queue, rq);
-
-       if (hctx->cmd_size)
-               rq->special = blk_mq_rq_to_pdu(rq);
-}
-
 static void __blk_mq_free_request(struct blk_mq_hw_ctx *hctx,
                                  struct blk_mq_ctx *ctx, struct request *rq)
 {
        const int tag = rq->tag;
        struct request_queue *q = rq->q;
 
-       blk_mq_rq_init(hctx, rq);
+       blk_rq_init(hctx->queue, rq);
        blk_mq_put_tag(hctx->tags, tag);
 
        blk_mq_queue_exit(q);
@@ -1165,7 +1154,7 @@ static int blk_mq_init_rq_map(struct blk_mq_hw_ctx *hctx,
                left -= to_do * rq_size;
                for (j = 0; j < to_do; j++) {
                        hctx->rqs[i] = p;
-                       blk_mq_rq_init(hctx, hctx->rqs[i]);
+                       blk_rq_init(hctx->queue, hctx->rqs[i]);
                        p += rq_size;
                        i++;
                }

diff --git a/block/blk-mq.h b/block/blk-mq.h
index ebbe6bac9d616d4a47a815870dc9d3682403c9d1..238379a612e420ebd8af08abf93bfee10df1f33e 100644 (file)
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -27,7 +27,6 @@ void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async);
 void blk_mq_init_flush(struct request_queue *q);
 void blk_mq_drain_queue(struct request_queue *q);
 void blk_mq_free_queue(struct request_queue *q);
-void blk_mq_rq_init(struct blk_mq_hw_ctx *hctx, struct request *rq);
 
 /*
  * CPU hotplug helpers

diff --git a/drivers/block/null_blk.c b/drivers/block/null_blk.c
index 091b9ea14feb5856ceada49671197dfac567376c..71df69d90900623586bd0962e5ad5df3a7ccd310 100644 (file)
--- a/drivers/block/null_blk.c
+++ b/drivers/block/null_blk.c
@@ -226,7 +226,7 @@ static void null_cmd_end_timer(struct nullb_cmd *cmd)
 
 static void null_softirq_done_fn(struct request *rq)
 {
-       end_cmd(rq->special);
+       end_cmd(blk_mq_rq_to_pdu(rq));
 }
 
 static inline void null_handle_cmd(struct nullb_cmd *cmd)
@@ -311,7 +311,7 @@ static void null_request_fn(struct request_queue *q)
 
 static int null_queue_rq(struct blk_mq_hw_ctx *hctx, struct request *rq)
 {
-       struct nullb_cmd *cmd = rq->special;
+       struct nullb_cmd *cmd = blk_mq_rq_to_pdu(rq);
 
        cmd->rq = rq;
        cmd->nq = hctx->driver_data;

diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 6d8a87f252de563f1251872e5bccbd25e2e64cf7..c7d02bc9d945cf590931d479ff552b65a75fc3b3 100644 (file)
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -112,7 +112,7 @@ static int __virtblk_add_req(struct virtqueue *vq,
 
 static inline void virtblk_request_done(struct request *req)
 {
-       struct virtblk_req *vbr = req->special;
+       struct virtblk_req *vbr = blk_mq_rq_to_pdu(req);
        int error = virtblk_result(vbr);
 
        if (req->cmd_type == REQ_TYPE_BLOCK_PC) {
@@ -154,7 +154,7 @@ static void virtblk_done(struct virtqueue *vq)
 static int virtio_queue_rq(struct blk_mq_hw_ctx *hctx, struct request *req)
 {
        struct virtio_blk *vblk = hctx->queue->queuedata;
-       struct virtblk_req *vbr = req->special;
+       struct virtblk_req *vbr = blk_mq_rq_to_pdu(req);
        unsigned long flags;
        unsigned int num;
        const bool last = (req->cmd_flags & REQ_END) != 0;
@@ -501,7 +501,7 @@ static int virtblk_init_vbr(void *data, struct blk_mq_hw_ctx *hctx,
                             struct request *rq, unsigned int nr)
 {
        struct virtio_blk *vblk = data;
-       struct virtblk_req *vbr = rq->special;
+       struct virtblk_req *vbr = blk_mq_rq_to_pdu(rq);
 
        sg_init_table(vbr->sg, vblk->sg_elems);
        return 0;