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blk-mq: do not initialize req->special

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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>
This commit is contained in:
Christoph Hellwig 2014-04-14 10:30:07 +02:00 committed by Jens Axboe
parent 742ee69b92
commit 9d74e25737
5 changed files with 9 additions and 27 deletions
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10
block/blk-flush.c
View File

@ -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;

15
block/blk-mq.c
View File

@ -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++;
}

1
block/blk-mq.h
View File

@ -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

4
drivers/block/null_blk.c
View File

@ -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;

6
drivers/block/virtio_blk.c
View File

@ -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;