[PATCH 12/14] blk-mq: introduce pointers to dispatch lock & list

Ming Lei
2017-07-31T16:53:23Z

Prepare to support per-request-queue dispatch list,
so introduce dispatch lock and list for avoiding to
do runtime check.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
block/blk-mq-debugfs.c | 10 +++++-----
block/blk-mq.c | 7 +++++--
block/blk-mq.h | 26 +++++++++++++-------------
include/linux/blk-mq.h | 3 +++
4 files changed, 26 insertions(+), 20 deletions(-)

diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index c4f70b453c76..4f8cddb8505f 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -370,23 +370,23 @@ static void *hctx_dispatch_start(struct seq_file *m, loff_t *pos)
{
struct blk_mq_hw_ctx *hctx = m->private;

- spin_lock(&hctx->lock);
- return seq_list_start(&hctx->dispatch, *pos);
+ spin_lock(hctx->dispatch_lock);
+ return seq_list_start(hctx->dispatch_list, *pos);
}

static void *hctx_dispatch_next(struct seq_file *m, void *v, loff_t *pos)
{
struct blk_mq_hw_ctx *hctx = m->private;

- return seq_list_next(v, &hctx->dispatch, pos);
+ return seq_list_next(v, hctx->dispatch_list, pos);
}

static void hctx_dispatch_stop(struct seq_file *m, void *v)
- __releases(&hctx->lock)
+ __releases(hctx->dispatch_lock)
{
struct blk_mq_hw_ctx *hctx = m->private;

- spin_unlock(&hctx->lock);
+ spin_unlock(hctx->dispatch_lock);
}

static const struct seq_operations hctx_dispatch_seq_ops = {
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 785145f60c1d..9b8b3a740d18 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1925,8 +1925,11 @@ static void blk_mq_exit_hw_queues(struct request_queue *q,
static void blk_mq_init_dispatch(struct request_queue *q,
struct blk_mq_hw_ctx *hctx)
{
- spin_lock_init(&hctx->lock);
- INIT_LIST_HEAD(&hctx->dispatch);
+ hctx->dispatch_lock = &hctx->lock;
+ hctx->dispatch_list = &hctx->dispatch;
+
+ spin_lock_init(hctx->dispatch_lock);
+ INIT_LIST_HEAD(hctx->dispatch_list);
}

static int blk_mq_init_hctx(struct request_queue *q,
diff --git a/block/blk-mq.h b/block/blk-mq.h
index 2ed355881996..d9795cbba1bb 100644
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -152,38 +152,38 @@ static inline void blk_mq_hctx_clear_busy(struct blk_mq_hw_ctx *hctx)

static inline bool blk_mq_has_dispatch_rqs(struct blk_mq_hw_ctx *hctx)
{
- return !list_empty_careful(&hctx->dispatch);
+ return !list_empty_careful(hctx->dispatch_list);
}

static inline void blk_mq_add_rq_to_dispatch(struct blk_mq_hw_ctx *hctx,
struct request *rq)
{
- spin_lock(&hctx->lock);
- list_add(&rq->queuelist, &hctx->dispatch);
- spin_unlock(&hctx->lock);
+ spin_lock(hctx->dispatch_lock);
+ list_add(&rq->queuelist, hctx->dispatch_list);
+ spin_unlock(hctx->dispatch_lock);
}

static inline void blk_mq_add_list_to_dispatch(struct blk_mq_hw_ctx *hctx,
struct list_head *list)
{
- spin_lock(&hctx->lock);
- list_splice_init(list, &hctx->dispatch);
- spin_unlock(&hctx->lock);
+ spin_lock(hctx->dispatch_lock);
+ list_splice_init(list, hctx->dispatch_list);
+ spin_unlock(hctx->dispatch_lock);
}

static inline void blk_mq_add_list_to_dispatch_tail(struct blk_mq_hw_ctx *hctx,
struct list_head *list)
{
- spin_lock(&hctx->lock);
- list_splice_tail_init(list, &hctx->dispatch);
- spin_unlock(&hctx->lock);
+ spin_lock(hctx->dispatch_lock);
+ list_splice_tail_init(list, hctx->dispatch_list);
+ spin_unlock(hctx->dispatch_lock);
}

static inline void blk_mq_take_list_from_dispatch(struct blk_mq_hw_ctx *hctx,
struct list_head *list)
{
- spin_lock(&hctx->lock);
- list_splice_init(&hctx->dispatch, list);
+ spin_lock(hctx->dispatch_lock);
+ list_splice_init(hctx->dispatch_list, list);

/*
* BUSY won't be cleared until all requests
@@ -191,7 +191,7 @@ static inline void blk_mq_take_list_from_dispatch(struct blk_mq_hw_ctx *hctx,
*/
if (!list_empty(list))
blk_mq_hctx_set_busy(hctx);
- spin_unlock(&hctx->lock);
+ spin_unlock(hctx->dispatch_lock);
}

#endif
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index 14f2ad3af31f..016f16c48f72 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -22,6 +22,9 @@ struct blk_mq_hw_ctx {

unsigned long flags; /* BLK_MQ_F_* flags */

+ spinlock_t *dispatch_lock;
+ struct list_head *dispatch_list;
+
void *sched_data;
struct request_queue *queue;
struct blk_flush_queue *fq;
--
2.9.4