[PATCH 5/6] blk-mq: add struct blk_mq_ctx_type

[Jens Axboe <axboe@kernel.dk>]

This only holds the dispatch list for now, and there should be no
functional changes in this patch. This is in preparation for adding more
items to the per-ctx type structure.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 block/blk-mq-debugfs.c |  6 +++---
 block/blk-mq-sched.c   |  4 ++--
 block/blk-mq.c         | 22 +++++++++++-----------
 block/blk-mq.h         |  6 +++++-
 4 files changed, 21 insertions(+), 17 deletions(-)

diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index b3f2ba483992..e789f830ff59 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -622,14 +622,14 @@ static int hctx_dispatch_busy_show(void *data, struct seq_file *m)
 	return 0;
 }
 
-#define CTX_RQ_SEQ_OPS(name, type)					\
+#define CTX_RQ_SEQ_OPS(name, __type)					\
 static void *ctx_##name##_rq_list_start(struct seq_file *m, loff_t *pos) \
 	__acquires(&ctx->lock)						\
 {									\
 	struct blk_mq_ctx *ctx = m->private;				\
 									\
 	spin_lock(&ctx->lock);						\
-	return seq_list_start(&ctx->rq_lists[type], *pos);		\
+	return seq_list_start(&ctx->type[__type].rq_list, *pos);		\
 }									\
 									\
 static void *ctx_##name##_rq_list_next(struct seq_file *m, void *v,	\
@@ -637,7 +637,7 @@ static void *ctx_##name##_rq_list_next(struct seq_file *m, void *v,	\
 {									\
 	struct blk_mq_ctx *ctx = m->private;				\
 									\
-	return seq_list_next(v, &ctx->rq_lists[type], pos);		\
+	return seq_list_next(v, &ctx->type[__type].rq_list, pos);	\
 }									\
 									\
 static void ctx_##name##_rq_list_stop(struct seq_file *m, void *v)	\
diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index ca22afd47b3d..52368c9005e5 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -313,7 +313,7 @@ static bool blk_mq_attempt_merge(struct request_queue *q,
 
 	lockdep_assert_held(&ctx->lock);
 
-	if (blk_mq_bio_list_merge(q, &ctx->rq_lists[type], bio, nr_segs)) {
+	if (blk_mq_bio_list_merge(q, &ctx->type[type].rq_list, bio, nr_segs)) {
 		ctx->rq_merged++;
 		return true;
 	}
@@ -335,7 +335,7 @@ bool __blk_mq_sched_bio_merge(struct request_queue *q, struct bio *bio,
 
 	type = hctx->type;
 	if ((hctx->flags & BLK_MQ_F_SHOULD_MERGE) &&
-			!list_empty_careful(&ctx->rq_lists[type])) {
+			!list_empty_careful(&ctx->type[type].rq_list)) {
 		/* default per sw-queue merge */
 		spin_lock(&ctx->lock);
 		ret = blk_mq_attempt_merge(q, hctx, ctx, bio, nr_segs);
diff --git a/block/blk-mq.c b/block/blk-mq.c
index a36764c38bfb..cc48a0ffa5ec 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -953,7 +953,7 @@ static bool flush_busy_ctx(struct sbitmap *sb, unsigned int bitnr, void *data)
 	enum hctx_type type = hctx->type;
 
 	spin_lock(&ctx->lock);
-	list_splice_tail_init(&ctx->rq_lists[type], flush_data->list);
+	list_splice_tail_init(&ctx->type[type].rq_list, flush_data->list);
 	sbitmap_clear_bit(sb, bitnr);
 	spin_unlock(&ctx->lock);
 	return true;
@@ -985,13 +985,13 @@ static bool dispatch_rq_from_ctx(struct sbitmap *sb, unsigned int bitnr,
 	struct dispatch_rq_data *dispatch_data = data;
 	struct blk_mq_hw_ctx *hctx = dispatch_data->hctx;
 	struct blk_mq_ctx *ctx = hctx->ctxs[bitnr];
-	enum hctx_type type = hctx->type;
+	struct blk_mq_ctx_type *type = &ctx->type[hctx->type];
 
 	spin_lock(&ctx->lock);
-	if (!list_empty(&ctx->rq_lists[type])) {
-		dispatch_data->rq = list_entry_rq(ctx->rq_lists[type].next);
+	if (!list_empty(&type->rq_list)) {
+		dispatch_data->rq = list_entry_rq(type->rq_list.next);
 		list_del_init(&dispatch_data->rq->queuelist);
-		if (list_empty(&ctx->rq_lists[type]))
+		if (list_empty(&type->rq_list))
 			sbitmap_clear_bit(sb, bitnr);
 	}
 	spin_unlock(&ctx->lock);
@@ -1648,9 +1648,9 @@ static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx *hctx,
 	trace_block_rq_insert(hctx->queue, rq);
 
 	if (at_head)
-		list_add(&rq->queuelist, &ctx->rq_lists[type]);
+		list_add(&rq->queuelist, &ctx->type[type].rq_list);
 	else
-		list_add_tail(&rq->queuelist, &ctx->rq_lists[type]);
+		list_add_tail(&rq->queuelist, &ctx->type[type].rq_list);
 }
 
 void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
@@ -1701,7 +1701,7 @@ void blk_mq_insert_requests(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
 	}
 
 	spin_lock(&ctx->lock);
-	list_splice_tail_init(list, &ctx->rq_lists[type]);
+	list_splice_tail_init(list, &ctx->type[type].rq_list);
 	blk_mq_hctx_mark_pending(hctx, ctx);
 	spin_unlock(&ctx->lock);
 }
@@ -2256,8 +2256,8 @@ static int blk_mq_hctx_notify_dead(unsigned int cpu, struct hlist_node *node)
 	type = hctx->type;
 
 	spin_lock(&ctx->lock);
-	if (!list_empty(&ctx->rq_lists[type])) {
-		list_splice_init(&ctx->rq_lists[type], &tmp);
+	if (!list_empty(&ctx->type[type].rq_list)) {
+		list_splice_init(&ctx->type[type].rq_list, &tmp);
 		blk_mq_hctx_clear_pending(hctx, ctx);
 	}
 	spin_unlock(&ctx->lock);
@@ -2437,7 +2437,7 @@ static void blk_mq_init_cpu_queues(struct request_queue *q,
 		__ctx->cpu = i;
 		spin_lock_init(&__ctx->lock);
 		for (k = HCTX_TYPE_DEFAULT; k < HCTX_MAX_TYPES; k++)
-			INIT_LIST_HEAD(&__ctx->rq_lists[k]);
+			INIT_LIST_HEAD(&__ctx->type[k].rq_list);
 
 		/*
 		 * Set local node, IFF we have more than one hw queue. If
diff --git a/block/blk-mq.h b/block/blk-mq.h
index d15ef0bafe29..271f16771499 100644
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -12,13 +12,17 @@ struct blk_mq_ctxs {
 	struct blk_mq_ctx __percpu	*queue_ctx;
 };
 
+struct blk_mq_ctx_type {
+	struct list_head		rq_list;
+};
+
 /**
  * struct blk_mq_ctx - State for a software queue facing the submitting CPUs
  */
 struct blk_mq_ctx {
 	struct {
 		spinlock_t		lock;
-		struct list_head	rq_lists[HCTX_MAX_TYPES];
+		struct blk_mq_ctx_type	type[HCTX_MAX_TYPES];
 	} ____cacheline_aligned_in_smp;
 
 	unsigned int		cpu;
-- 
2.24.1