[PATCH 11/14] blk-mq: introduce helpers for operating ->dispatch list

Ming Lei
2017-07-31T16:53:16Z

Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
block/blk-mq-sched.c | 19 +++----------------
block/blk-mq.c | 18 +++++++++++-------
block/blk-mq.h | 44 ++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 58 insertions(+), 23 deletions(-)

diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index 112270961af0..8ff74efe4172 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -131,19 +131,8 @@ void blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx)
* If we have previous entries on our dispatch list, grab them first for
* more fair dispatch.
*/
- if (!list_empty_careful(&hctx->dispatch)) {
- spin_lock(&hctx->lock);
- if (!list_empty(&hctx->dispatch)) {
- list_splice_init(&hctx->dispatch, &rq_list);
-
- /*
- * BUSY won't be cleared until all requests
- * in hctx->dispatch are dispatched successfully
- */
- blk_mq_hctx_set_busy(hctx);
- }
- spin_unlock(&hctx->lock);
- }
+ if (blk_mq_has_dispatch_rqs(hctx))
+ blk_mq_take_list_from_dispatch(hctx, &rq_list);

/*
* Only ask the scheduler for requests, if we didn't have residual
@@ -296,9 +285,7 @@ static bool blk_mq_sched_bypass_insert(struct blk_mq_hw_ctx *hctx,
* If we already have a real request tag, send directly to
* the dispatch list.
*/
- spin_lock(&hctx->lock);
- list_add(&rq->queuelist, &hctx->dispatch);
- spin_unlock(&hctx->lock);
+ blk_mq_add_rq_to_dispatch(hctx, rq);
return true;
}

diff --git a/block/blk-mq.c b/block/blk-mq.c
index db635ef06a72..785145f60c1d 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -63,7 +63,7 @@ static int blk_mq_poll_stats_bkt(const struct request *rq)
bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx *hctx)
{
return sbitmap_any_bit_set(&hctx->ctx_map) ||
- !list_empty_careful(&hctx->dispatch) ||
+ blk_mq_has_dispatch_rqs(hctx) ||
blk_mq_sched_has_work(hctx);
}

@@ -1097,9 +1097,7 @@ bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list)
rq = list_first_entry(list, struct request, queuelist);
blk_mq_put_driver_tag(rq);

- spin_lock(&hctx->lock);
- list_splice_init(list, &hctx->dispatch);
- spin_unlock(&hctx->lock);
+ blk_mq_add_list_to_dispatch(hctx, list);

/*
* If SCHED_RESTART was set by the caller of this function and
@@ -1874,9 +1872,7 @@ static int blk_mq_hctx_notify_dead(unsigned int cpu, struct hlist_node *node)
if (list_empty(&tmp))
return 0;

- spin_lock(&hctx->lock);
- list_splice_tail_init(&tmp, &hctx->dispatch);
- spin_unlock(&hctx->lock);
+ blk_mq_add_list_to_dispatch_tail(hctx, &tmp);

blk_mq_run_hw_queue(hctx, true);
return 0;
@@ -1926,6 +1922,13 @@ 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);
+}
+
static int blk_mq_init_hctx(struct request_queue *q,
struct blk_mq_tag_set *set,
struct blk_mq_hw_ctx *hctx, unsigned hctx_idx)
@@ -1939,6 +1942,7 @@ static int blk_mq_init_hctx(struct request_queue *q,
INIT_DELAYED_WORK(&hctx->run_work, blk_mq_run_work_fn);
spin_lock_init(&hctx->lock);
INIT_LIST_HEAD(&hctx->dispatch);
+ blk_mq_init_dispatch(q, hctx);
hctx->queue = q;
hctx->flags = set->flags & ~BLK_MQ_F_TAG_SHARED;

diff --git a/block/blk-mq.h b/block/blk-mq.h
index d9f875093613..2ed355881996 100644
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -150,4 +150,48 @@ static inline void blk_mq_hctx_clear_busy(struct blk_mq_hw_ctx *hctx)
clear_bit(BLK_MQ_S_BUSY, &hctx->state);
}

+static inline bool blk_mq_has_dispatch_rqs(struct blk_mq_hw_ctx *hctx)
+{
+ return !list_empty_careful(&hctx->dispatch);
+}
+
+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);
+}
+
+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);
+}
+
+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);
+}
+
+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);
+
+ /*
+ * BUSY won't be cleared until all requests
+ * in hctx->dispatch are dispatched successfully
+ */
+ if (!list_empty(list))
+ blk_mq_hctx_set_busy(hctx);
+ spin_unlock(&hctx->lock);
+}
+
#endif
--
2.9.4