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Date: Mon, 31 Mar 2014 16:46:12 +0200
From: Christoph Hellwig <hch@....de>
To: Jens Axboe <axboe@...com>
Cc: Matias Bjorling <m@...rling.me>, linux-kernel@...r.kernel.org,
linux-scsi@...r.kernel.org
Subject: [PATCH 1/4] blk->mq: stop pre-initializing req->special
We can get at the private data easil using pointer arithmetics. Do so
instead of initializing req->special so that we don't rely on the
request state in various initialization functions and shave off another
few instructions in the fast path.
Signed-off-by: Christoph Hellwig <hch@....de>
---
block/blk-flush.c | 10 ++--------
block/blk-mq.c | 15 ++-------------
block/blk-mq.h | 1 -
drivers/block/null_blk.c | 4 ++--
drivers/block/virtio_blk.c | 6 +++---
5 files changed, 9 insertions(+), 27 deletions(-)
diff --git a/block/blk-flush.c b/block/blk-flush.c
index 43e6b47..9a0c427 100644
--- 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 4274ee0..871acd6 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -248,24 +248,13 @@ 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);
@@ -1139,7 +1128,7 @@ 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 ebbe6ba..238379a 100644
--- 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 091b9ea..71df69d 100644
--- 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 0eace43..11e8f4b 100644
--- 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;
@@ -494,7 +494,7 @@ 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;
--
1.7.10.4
--
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