[PATCH V6 2/8] blk-mq: add new state of BLK_MQ_S_INACTIVE

[Ming Lei <ming.lei@redhat.com>]

Add a new hw queue state of BLK_MQ_S_INACTIVE, which is set when all
CPUs of this hctx are offline.

Prepares for stopping hw queue when all CPUs of this hctx become offline.

Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Garry <john.garry@huawei.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 block/blk-mq-debugfs.c | 1 +
 block/blk-mq.h         | 3 ++-
 include/linux/blk-mq.h | 3 +++
 3 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index b3f2ba483992..d6de4f7f38cb 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -213,6 +213,7 @@ static const char *const hctx_state_name[] = {
 	HCTX_STATE_NAME(STOPPED),
 	HCTX_STATE_NAME(TAG_ACTIVE),
 	HCTX_STATE_NAME(SCHED_RESTART),
+	HCTX_STATE_NAME(INACTIVE),
 };
 #undef HCTX_STATE_NAME
 
diff --git a/block/blk-mq.h b/block/blk-mq.h
index d25429a4932c..1f4a794ddeb7 100644
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -168,7 +168,8 @@ static inline struct blk_mq_tags *blk_mq_tags_from_data(struct blk_mq_alloc_data
 
 static inline bool blk_mq_hctx_stopped(struct blk_mq_hw_ctx *hctx)
 {
-	return test_bit(BLK_MQ_S_STOPPED, &hctx->state);
+	return test_bit(BLK_MQ_S_STOPPED, &hctx->state) ||
+		test_bit(BLK_MQ_S_INACTIVE, &hctx->state);
 }
 
 static inline bool blk_mq_hw_queue_mapped(struct blk_mq_hw_ctx *hctx)
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index 11cfd6470b1a..b669e776d4cb 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -397,6 +397,9 @@ enum {
 	BLK_MQ_S_TAG_ACTIVE	= 1,
 	BLK_MQ_S_SCHED_RESTART	= 2,
 
+	/* hw queue is inactive after all its CPUs become offline */
+	BLK_MQ_S_INACTIVE	= 3,
+
 	BLK_MQ_MAX_DEPTH	= 10240,
 
 	BLK_MQ_CPU_WORK_BATCH	= 8,
-- 
2.25.2