[RFC,v7,05/12] blk-mq: Record nr_active_requests per queue for when using shared sbitmap

Message ID 1591810159-240929-6-git-send-email-john.garry@huawei.com
State New
Headers show
Series
  • blk-mq/scsi: Provide hostwide shared tags for SCSI HBAs
Related show

Commit Message

John Garry June 10, 2020, 5:29 p.m.
The per-hctx nr_active value can no longer be used to fairly assign a share
of tag depth per request queue for when using a shared sbitmap, as it does
not consider that the tags are shared tags over all hctx's.

For this case, record the nr_active_requests per request_queue, and make
the judgment based on that value.

Also introduce a debugfs version of per-hctx blk_mq_debugfs_attr, omitting
hctx_active_show() (as blk_mq_hw_ctx.nr_active is no longer maintained for
the case of shared sbitmap) and other entries which we can add which would
be revised specifically for when using a shared sbitmap.

Co-developed-with: Kashyap Desai <kashyap.desai@broadcom.com>
Signed-off-by: John Garry <john.garry@huawei.com>

---
 block/blk-core.c       |  2 ++
 block/blk-mq-debugfs.c | 23 ++++++++++++++++++++++-
 block/blk-mq-tag.c     | 10 ++++++----
 block/blk-mq.c         |  6 +++---
 block/blk-mq.h         | 28 +++++++++++++++++++++++++++-
 include/linux/blkdev.h |  2 ++
 6 files changed, 62 insertions(+), 9 deletions(-)

-- 
2.26.2

Comments

Ming Lei June 11, 2020, 4:04 a.m. | #1
On Thu, Jun 11, 2020 at 01:29:12AM +0800, John Garry wrote:
> The per-hctx nr_active value can no longer be used to fairly assign a share

> of tag depth per request queue for when using a shared sbitmap, as it does

> not consider that the tags are shared tags over all hctx's.

> 

> For this case, record the nr_active_requests per request_queue, and make

> the judgment based on that value.

> 

> Also introduce a debugfs version of per-hctx blk_mq_debugfs_attr, omitting

> hctx_active_show() (as blk_mq_hw_ctx.nr_active is no longer maintained for

> the case of shared sbitmap) and other entries which we can add which would

> be revised specifically for when using a shared sbitmap.

> 

> Co-developed-with: Kashyap Desai <kashyap.desai@broadcom.com>

> Signed-off-by: John Garry <john.garry@huawei.com>

> ---

>  block/blk-core.c       |  2 ++

>  block/blk-mq-debugfs.c | 23 ++++++++++++++++++++++-

>  block/blk-mq-tag.c     | 10 ++++++----

>  block/blk-mq.c         |  6 +++---

>  block/blk-mq.h         | 28 +++++++++++++++++++++++++++-

>  include/linux/blkdev.h |  2 ++

>  6 files changed, 62 insertions(+), 9 deletions(-)

> 

> diff --git a/block/blk-core.c b/block/blk-core.c

> index 03252af8c82c..c622453c1363 100644

> --- a/block/blk-core.c

> +++ b/block/blk-core.c

> @@ -529,6 +529,8 @@ struct request_queue *__blk_alloc_queue(int node_id)

>  	q->backing_dev_info->capabilities = BDI_CAP_CGROUP_WRITEBACK;

>  	q->node = node_id;

>  

> +	atomic_set(&q->nr_active_requests_shared_sbitmap, 0);

> +

>  	timer_setup(&q->backing_dev_info->laptop_mode_wb_timer,

>  		    laptop_mode_timer_fn, 0);

>  	timer_setup(&q->timeout, blk_rq_timed_out_timer, 0);

> diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c

> index a400b6698dff..0fa3af41ab65 100644

> --- a/block/blk-mq-debugfs.c

> +++ b/block/blk-mq-debugfs.c

> @@ -796,6 +796,23 @@ static const struct blk_mq_debugfs_attr blk_mq_debugfs_hctx_attrs[] = {

>  	{},

>  };

>  

> +static const struct blk_mq_debugfs_attr blk_mq_debugfs_hctx_shared_sbitmap_attrs[] = {

> +	{"state", 0400, hctx_state_show},

> +	{"flags", 0400, hctx_flags_show},

> +	{"dispatch", 0400, .seq_ops = &hctx_dispatch_seq_ops},

> +	{"busy", 0400, hctx_busy_show},

> +	{"ctx_map", 0400, hctx_ctx_map_show},

> +	{"sched_tags", 0400, hctx_sched_tags_show},

> +	{"sched_tags_bitmap", 0400, hctx_sched_tags_bitmap_show},

> +	{"io_poll", 0600, hctx_io_poll_show, hctx_io_poll_write},

> +	{"dispatched", 0600, hctx_dispatched_show, hctx_dispatched_write},

> +	{"queued", 0600, hctx_queued_show, hctx_queued_write},

> +	{"run", 0600, hctx_run_show, hctx_run_write},

> +	{"active", 0400, hctx_active_show},

> +	{"dispatch_busy", 0400, hctx_dispatch_busy_show},

> +	{}

> +};


You may use macro or whatever to avoid so the duplication.

> +

>  static const struct blk_mq_debugfs_attr blk_mq_debugfs_ctx_attrs[] = {

>  	{"default_rq_list", 0400, .seq_ops = &ctx_default_rq_list_seq_ops},

>  	{"read_rq_list", 0400, .seq_ops = &ctx_read_rq_list_seq_ops},

> @@ -878,13 +895,17 @@ void blk_mq_debugfs_register_hctx(struct request_queue *q,

>  				  struct blk_mq_hw_ctx *hctx)

>  {

>  	struct blk_mq_ctx *ctx;

> +	struct blk_mq_tag_set *set = q->tag_set;

>  	char name[20];

>  	int i;

>  

>  	snprintf(name, sizeof(name), "hctx%u", hctx->queue_num);

>  	hctx->debugfs_dir = debugfs_create_dir(name, q->debugfs_dir);

>  

> -	debugfs_create_files(hctx->debugfs_dir, hctx, blk_mq_debugfs_hctx_attrs);

> +	if (blk_mq_is_sbitmap_shared(set))

> +		debugfs_create_files(hctx->debugfs_dir, hctx, blk_mq_debugfs_hctx_shared_sbitmap_attrs);

> +	else

> +		debugfs_create_files(hctx->debugfs_dir, hctx, blk_mq_debugfs_hctx_attrs);

>  

>  	hctx_for_each_ctx(hctx, ctx, i)

>  		blk_mq_debugfs_register_ctx(hctx, ctx);

> diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c

> index 92843e3e1a2a..7db16e49f6f6 100644

> --- a/block/blk-mq-tag.c

> +++ b/block/blk-mq-tag.c

> @@ -60,9 +60,11 @@ void __blk_mq_tag_idle(struct blk_mq_hw_ctx *hctx)

>   * For shared tag users, we track the number of currently active users

>   * and attempt to provide a fair share of the tag depth for each of them.

>   */

> -static inline bool hctx_may_queue(struct blk_mq_hw_ctx *hctx,

> +static inline bool hctx_may_queue(struct blk_mq_alloc_data *data,

>  				  struct sbitmap_queue *bt)

>  {

> +	struct blk_mq_hw_ctx *hctx = data->hctx;

> +	struct request_queue *q = data->q;

>  	unsigned int depth, users;

>  

>  	if (!hctx || !(hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED))

> @@ -84,15 +86,15 @@ static inline bool hctx_may_queue(struct blk_mq_hw_ctx *hctx,

>  	 * Allow at least some tags

>  	 */

>  	depth = max((bt->sb.depth + users - 1) / users, 4U);

> -	return atomic_read(&hctx->nr_active) < depth;

> +	return __blk_mq_active_requests(hctx, q) < depth;


There is big change on 'users' too:

	users = atomic_read(&hctx->tags->active_queues);

Originally there is single hctx->tags for these HBAs, now there are many
hctx->tags, so 'users' may become much smaller than before.

Maybe '->active_queues' can be moved to tag_set for blk_mq_is_sbitmap_shared().

>  }

>  

>  static int __blk_mq_get_tag(struct blk_mq_alloc_data *data,

>  			    struct sbitmap_queue *bt)

>  {

>  	if (!(data->flags & BLK_MQ_REQ_INTERNAL) &&

> -	    !hctx_may_queue(data->hctx, bt))

> -		return BLK_MQ_NO_TAG;

> +	    !hctx_may_queue(data, bt))

> +		return -1;


BLK_MQ_NO_TAG should have been returned.

>  	if (data->shallow_depth)

>  		return __sbitmap_queue_get_shallow(bt, data->shallow_depth);

>  	else

> diff --git a/block/blk-mq.c b/block/blk-mq.c

> index 77120dd4e4d5..0f7e062a1665 100644

> --- a/block/blk-mq.c

> +++ b/block/blk-mq.c

> @@ -283,7 +283,7 @@ static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data,

>  	} else {

>  		if (data->hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED) {

>  			rq_flags = RQF_MQ_INFLIGHT;

> -			atomic_inc(&data->hctx->nr_active);

> +			__blk_mq_inc_active_requests(data->hctx, data->q);

>  		}

>  		rq->tag = tag;

>  		rq->internal_tag = BLK_MQ_NO_TAG;

> @@ -527,7 +527,7 @@ void blk_mq_free_request(struct request *rq)

>  

>  	ctx->rq_completed[rq_is_sync(rq)]++;

>  	if (rq->rq_flags & RQF_MQ_INFLIGHT)

> -		atomic_dec(&hctx->nr_active);

> +		__blk_mq_dec_active_requests(hctx, q);

>  

>  	if (unlikely(laptop_mode && !blk_rq_is_passthrough(rq)))

>  		laptop_io_completion(q->backing_dev_info);

> @@ -1073,7 +1073,7 @@ bool blk_mq_get_driver_tag(struct request *rq)

>  	if (rq->tag >= 0) {

>  		if (shared) {

>  			rq->rq_flags |= RQF_MQ_INFLIGHT;

> -			atomic_inc(&data.hctx->nr_active);

> +			__blk_mq_inc_active_requests(rq->mq_hctx, rq->q);

>  		}

>  		data.hctx->tags->rqs[rq->tag] = rq;

>  	}

> diff --git a/block/blk-mq.h b/block/blk-mq.h

> index 1a283c707215..9c1e612c2298 100644

> --- a/block/blk-mq.h

> +++ b/block/blk-mq.h

> @@ -202,6 +202,32 @@ static inline bool blk_mq_get_dispatch_budget(struct blk_mq_hw_ctx *hctx)

>  	return true;

>  }

>  

> +static inline void __blk_mq_inc_active_requests(struct blk_mq_hw_ctx *hctx,

> +						struct request_queue *q)

> +{

> +	if (blk_mq_is_sbitmap_shared(q->tag_set))

> +		atomic_inc(&q->nr_active_requests_shared_sbitmap);

> +	else

> +		atomic_inc(&hctx->nr_active);

> +}

> +

> +static inline void __blk_mq_dec_active_requests(struct blk_mq_hw_ctx *hctx,

> +						struct request_queue *q)

> +{

> +	if (blk_mq_is_sbitmap_shared(q->tag_set))

> +		atomic_dec(&q->nr_active_requests_shared_sbitmap);

> +	else

> +		atomic_dec(&hctx->nr_active);

> +}

> +

> +static inline int __blk_mq_active_requests(struct blk_mq_hw_ctx *hctx,

> +					   struct request_queue *q)

> +{

> +	if (blk_mq_is_sbitmap_shared(q->tag_set))


I'd suggest to add one hctx version of blk_mq_is_sbitmap_shared() since
q->tag_set is seldom used in fast path, and hctx->flags is more
efficient than tag_set->flags.


Thanks, 
Ming
John Garry June 11, 2020, 10:22 a.m. | #2
>> +static const struct blk_mq_debugfs_attr blk_mq_debugfs_hctx_shared_sbitmap_attrs[] = {

>> +	{"state", 0400, hctx_state_show},

>> +	{"flags", 0400, hctx_flags_show},

>> +	{"dispatch", 0400, .seq_ops = &hctx_dispatch_seq_ops},

>> +	{"busy", 0400, hctx_busy_show},

>> +	{"ctx_map", 0400, hctx_ctx_map_show},

>> +	{"sched_tags", 0400, hctx_sched_tags_show},

>> +	{"sched_tags_bitmap", 0400, hctx_sched_tags_bitmap_show},

>> +	{"io_poll", 0600, hctx_io_poll_show, hctx_io_poll_write},

>> +	{"dispatched", 0600, hctx_dispatched_show, hctx_dispatched_write},

>> +	{"queued", 0600, hctx_queued_show, hctx_queued_write},

>> +	{"run", 0600, hctx_run_show, hctx_run_write},

>> +	{"active", 0400, hctx_active_show},

>> +	{"dispatch_busy", 0400, hctx_dispatch_busy_show},

>> +	{}

>> +};

> 

> You may use macro or whatever to avoid so the duplication.


Let me check alternatives.

> 

>> +

>>   static const struct blk_mq_debugfs_attr blk_mq_debugfs_ctx_attrs[] = {

>>   	{"default_rq_list", 0400, .seq_ops = &ctx_default_rq_list_seq_ops},

>>   	{"read_rq_list", 0400, .seq_ops = &ctx_read_rq_list_seq_ops},

>> @@ -878,13 +895,17 @@ void blk_mq_debugfs_register_hctx(struct request_queue *q,

>>   				  struct blk_mq_hw_ctx *hctx)

>>   {

>>   	struct blk_mq_ctx *ctx;

>> +	struct blk_mq_tag_set *set = q->tag_set;

>>   	char name[20];

>>   	int i;

>>   

>>   	snprintf(name, sizeof(name), "hctx%u", hctx->queue_num);

>>   	hctx->debugfs_dir = debugfs_create_dir(name, q->debugfs_dir);

>>   

>> -	debugfs_create_files(hctx->debugfs_dir, hctx, blk_mq_debugfs_hctx_attrs);

>> +	if (blk_mq_is_sbitmap_shared(set))

>> +		debugfs_create_files(hctx->debugfs_dir, hctx, blk_mq_debugfs_hctx_shared_sbitmap_attrs);

>> +	else

>> +		debugfs_create_files(hctx->debugfs_dir, hctx, blk_mq_debugfs_hctx_attrs);

>>   

>>   	hctx_for_each_ctx(hctx, ctx, i)

>>   		blk_mq_debugfs_register_ctx(hctx, ctx);

>> diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c

>> index 92843e3e1a2a..7db16e49f6f6 100644

>> --- a/block/blk-mq-tag.c

>> +++ b/block/blk-mq-tag.c

>> @@ -60,9 +60,11 @@ void __blk_mq_tag_idle(struct blk_mq_hw_ctx *hctx)

>>    * For shared tag users, we track the number of currently active users

>>    * and attempt to provide a fair share of the tag depth for each of them.

>>    */

>> -static inline bool hctx_may_queue(struct blk_mq_hw_ctx *hctx,

>> +static inline bool hctx_may_queue(struct blk_mq_alloc_data *data,

>>   				  struct sbitmap_queue *bt)

>>   {

>> +	struct blk_mq_hw_ctx *hctx = data->hctx;

>> +	struct request_queue *q = data->q;

>>   	unsigned int depth, users;

>>   

>>   	if (!hctx || !(hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED))

>> @@ -84,15 +86,15 @@ static inline bool hctx_may_queue(struct blk_mq_hw_ctx *hctx,

>>   	 * Allow at least some tags

>>   	 */

>>   	depth = max((bt->sb.depth + users - 1) / users, 4U);

>> -	return atomic_read(&hctx->nr_active) < depth;

>> +	return __blk_mq_active_requests(hctx, q) < depth;

> 

> There is big change on 'users' too:

> 

> 	users = atomic_read(&hctx->tags->active_queues);

> 

> Originally there is single hctx->tags for these HBAs, now there are many

> hctx->tags, so 'users' may become much smaller than before.


Can you please check how I handled that in the next patch? There we 
record the number of active request queues per set.

(I will note that I could have combined some of these patches, but I 
liked the piecemeal appraoch, and none of these paths are enabled until 
later).

> 

> Maybe '->active_queues' can be moved to tag_set for blk_mq_is_sbitmap_shared().

> 

>>   }

>>   

>>   static int __blk_mq_get_tag(struct blk_mq_alloc_data *data,

>>   			    struct sbitmap_queue *bt)

>>   {

>>   	if (!(data->flags & BLK_MQ_REQ_INTERNAL) &&

>> -	    !hctx_may_queue(data->hctx, bt))

>> -		return BLK_MQ_NO_TAG;

>> +	    !hctx_may_queue(data, bt))

>> +		return -1;

> 

> BLK_MQ_NO_TAG should have been returned.


OK, I missed that in the rebase.

> 

>>   	if (data->shallow_depth)

>>   		return __sbitmap_queue_get_shallow(bt, data->shallow_depth);

>>   	else

>> diff --git a/block/blk-mq.c b/block/blk-mq.c

>> index 77120dd4e4d5..0f7e062a1665 100644

>> --- a/block/blk-mq.c

>> +++ b/block/blk-mq.c

>> @@ -283,7 +283,7 @@ static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data,

>>   	} else {

>>   		if (data->hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED) {

>>   			rq_flags = RQF_MQ_INFLIGHT;

>> -			atomic_inc(&data->hctx->nr_active);

>> +			__blk_mq_inc_active_requests(data->hctx, data->q);

>>   		}

>>   		rq->tag = tag;

>>   		rq->internal_tag = BLK_MQ_NO_TAG;

>> @@ -527,7 +527,7 @@ void blk_mq_free_request(struct request *rq)

>>   

>>   	ctx->rq_completed[rq_is_sync(rq)]++;

>>   	if (rq->rq_flags & RQF_MQ_INFLIGHT)

>> -		atomic_dec(&hctx->nr_active);

>> +		__blk_mq_dec_active_requests(hctx, q);

>>   

>>   	if (unlikely(laptop_mode && !blk_rq_is_passthrough(rq)))

>>   		laptop_io_completion(q->backing_dev_info);

>> @@ -1073,7 +1073,7 @@ bool blk_mq_get_driver_tag(struct request *rq)

>>   	if (rq->tag >= 0) {

>>   		if (shared) {

>>   			rq->rq_flags |= RQF_MQ_INFLIGHT;

>> -			atomic_inc(&data.hctx->nr_active);

>> +			__blk_mq_inc_active_requests(rq->mq_hctx, rq->q);

>>   		}

>>   		data.hctx->tags->rqs[rq->tag] = rq;

>>   	}

>> diff --git a/block/blk-mq.h b/block/blk-mq.h

>> index 1a283c707215..9c1e612c2298 100644

>> --- a/block/blk-mq.h

>> +++ b/block/blk-mq.h

>> @@ -202,6 +202,32 @@ static inline bool blk_mq_get_dispatch_budget(struct blk_mq_hw_ctx *hctx)

>>   	return true;

>>   }

>>   

>> +static inline void __blk_mq_inc_active_requests(struct blk_mq_hw_ctx *hctx,

>> +						struct request_queue *q)

>> +{

>> +	if (blk_mq_is_sbitmap_shared(q->tag_set))

>> +		atomic_inc(&q->nr_active_requests_shared_sbitmap);

>> +	else

>> +		atomic_inc(&hctx->nr_active);

>> +}

>> +

>> +static inline void __blk_mq_dec_active_requests(struct blk_mq_hw_ctx *hctx,

>> +						struct request_queue *q)

>> +{

>> +	if (blk_mq_is_sbitmap_shared(q->tag_set))

>> +		atomic_dec(&q->nr_active_requests_shared_sbitmap);

>> +	else

>> +		atomic_dec(&hctx->nr_active);

>> +}

>> +

>> +static inline int __blk_mq_active_requests(struct blk_mq_hw_ctx *hctx,

>> +					   struct request_queue *q)

>> +{

>> +	if (blk_mq_is_sbitmap_shared(q->tag_set))

> 

> I'd suggest to add one hctx version of blk_mq_is_sbitmap_shared() since

> q->tag_set is seldom used in fast path, and hctx->flags is more

> efficient than tag_set->flags.


OK

Thanks,
John

Patch

diff --git a/block/blk-core.c b/block/blk-core.c
index 03252af8c82c..c622453c1363 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -529,6 +529,8 @@  struct request_queue *__blk_alloc_queue(int node_id)
 	q->backing_dev_info->capabilities = BDI_CAP_CGROUP_WRITEBACK;
 	q->node = node_id;
 
+	atomic_set(&q->nr_active_requests_shared_sbitmap, 0);
+
 	timer_setup(&q->backing_dev_info->laptop_mode_wb_timer,
 		    laptop_mode_timer_fn, 0);
 	timer_setup(&q->timeout, blk_rq_timed_out_timer, 0);
diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index a400b6698dff..0fa3af41ab65 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -796,6 +796,23 @@  static const struct blk_mq_debugfs_attr blk_mq_debugfs_hctx_attrs[] = {
 	{},
 };
 
+static const struct blk_mq_debugfs_attr blk_mq_debugfs_hctx_shared_sbitmap_attrs[] = {
+	{"state", 0400, hctx_state_show},
+	{"flags", 0400, hctx_flags_show},
+	{"dispatch", 0400, .seq_ops = &hctx_dispatch_seq_ops},
+	{"busy", 0400, hctx_busy_show},
+	{"ctx_map", 0400, hctx_ctx_map_show},
+	{"sched_tags", 0400, hctx_sched_tags_show},
+	{"sched_tags_bitmap", 0400, hctx_sched_tags_bitmap_show},
+	{"io_poll", 0600, hctx_io_poll_show, hctx_io_poll_write},
+	{"dispatched", 0600, hctx_dispatched_show, hctx_dispatched_write},
+	{"queued", 0600, hctx_queued_show, hctx_queued_write},
+	{"run", 0600, hctx_run_show, hctx_run_write},
+	{"active", 0400, hctx_active_show},
+	{"dispatch_busy", 0400, hctx_dispatch_busy_show},
+	{}
+};
+
 static const struct blk_mq_debugfs_attr blk_mq_debugfs_ctx_attrs[] = {
 	{"default_rq_list", 0400, .seq_ops = &ctx_default_rq_list_seq_ops},
 	{"read_rq_list", 0400, .seq_ops = &ctx_read_rq_list_seq_ops},
@@ -878,13 +895,17 @@  void blk_mq_debugfs_register_hctx(struct request_queue *q,
 				  struct blk_mq_hw_ctx *hctx)
 {
 	struct blk_mq_ctx *ctx;
+	struct blk_mq_tag_set *set = q->tag_set;
 	char name[20];
 	int i;
 
 	snprintf(name, sizeof(name), "hctx%u", hctx->queue_num);
 	hctx->debugfs_dir = debugfs_create_dir(name, q->debugfs_dir);
 
-	debugfs_create_files(hctx->debugfs_dir, hctx, blk_mq_debugfs_hctx_attrs);
+	if (blk_mq_is_sbitmap_shared(set))
+		debugfs_create_files(hctx->debugfs_dir, hctx, blk_mq_debugfs_hctx_shared_sbitmap_attrs);
+	else
+		debugfs_create_files(hctx->debugfs_dir, hctx, blk_mq_debugfs_hctx_attrs);
 
 	hctx_for_each_ctx(hctx, ctx, i)
 		blk_mq_debugfs_register_ctx(hctx, ctx);
diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c
index 92843e3e1a2a..7db16e49f6f6 100644
--- a/block/blk-mq-tag.c
+++ b/block/blk-mq-tag.c
@@ -60,9 +60,11 @@  void __blk_mq_tag_idle(struct blk_mq_hw_ctx *hctx)
  * For shared tag users, we track the number of currently active users
  * and attempt to provide a fair share of the tag depth for each of them.
  */
-static inline bool hctx_may_queue(struct blk_mq_hw_ctx *hctx,
+static inline bool hctx_may_queue(struct blk_mq_alloc_data *data,
 				  struct sbitmap_queue *bt)
 {
+	struct blk_mq_hw_ctx *hctx = data->hctx;
+	struct request_queue *q = data->q;
 	unsigned int depth, users;
 
 	if (!hctx || !(hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED))
@@ -84,15 +86,15 @@  static inline bool hctx_may_queue(struct blk_mq_hw_ctx *hctx,
 	 * Allow at least some tags
 	 */
 	depth = max((bt->sb.depth + users - 1) / users, 4U);
-	return atomic_read(&hctx->nr_active) < depth;
+	return __blk_mq_active_requests(hctx, q) < depth;
 }
 
 static int __blk_mq_get_tag(struct blk_mq_alloc_data *data,
 			    struct sbitmap_queue *bt)
 {
 	if (!(data->flags & BLK_MQ_REQ_INTERNAL) &&
-	    !hctx_may_queue(data->hctx, bt))
-		return BLK_MQ_NO_TAG;
+	    !hctx_may_queue(data, bt))
+		return -1;
 	if (data->shallow_depth)
 		return __sbitmap_queue_get_shallow(bt, data->shallow_depth);
 	else
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 77120dd4e4d5..0f7e062a1665 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -283,7 +283,7 @@  static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data,
 	} else {
 		if (data->hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED) {
 			rq_flags = RQF_MQ_INFLIGHT;
-			atomic_inc(&data->hctx->nr_active);
+			__blk_mq_inc_active_requests(data->hctx, data->q);
 		}
 		rq->tag = tag;
 		rq->internal_tag = BLK_MQ_NO_TAG;
@@ -527,7 +527,7 @@  void blk_mq_free_request(struct request *rq)
 
 	ctx->rq_completed[rq_is_sync(rq)]++;
 	if (rq->rq_flags & RQF_MQ_INFLIGHT)
-		atomic_dec(&hctx->nr_active);
+		__blk_mq_dec_active_requests(hctx, q);
 
 	if (unlikely(laptop_mode && !blk_rq_is_passthrough(rq)))
 		laptop_io_completion(q->backing_dev_info);
@@ -1073,7 +1073,7 @@  bool blk_mq_get_driver_tag(struct request *rq)
 	if (rq->tag >= 0) {
 		if (shared) {
 			rq->rq_flags |= RQF_MQ_INFLIGHT;
-			atomic_inc(&data.hctx->nr_active);
+			__blk_mq_inc_active_requests(rq->mq_hctx, rq->q);
 		}
 		data.hctx->tags->rqs[rq->tag] = rq;
 	}
diff --git a/block/blk-mq.h b/block/blk-mq.h
index 1a283c707215..9c1e612c2298 100644
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -202,6 +202,32 @@  static inline bool blk_mq_get_dispatch_budget(struct blk_mq_hw_ctx *hctx)
 	return true;
 }
 
+static inline void __blk_mq_inc_active_requests(struct blk_mq_hw_ctx *hctx,
+						struct request_queue *q)
+{
+	if (blk_mq_is_sbitmap_shared(q->tag_set))
+		atomic_inc(&q->nr_active_requests_shared_sbitmap);
+	else
+		atomic_inc(&hctx->nr_active);
+}
+
+static inline void __blk_mq_dec_active_requests(struct blk_mq_hw_ctx *hctx,
+						struct request_queue *q)
+{
+	if (blk_mq_is_sbitmap_shared(q->tag_set))
+		atomic_dec(&q->nr_active_requests_shared_sbitmap);
+	else
+		atomic_dec(&hctx->nr_active);
+}
+
+static inline int __blk_mq_active_requests(struct blk_mq_hw_ctx *hctx,
+					   struct request_queue *q)
+{
+	if (blk_mq_is_sbitmap_shared(q->tag_set))
+		return atomic_read(&q->nr_active_requests_shared_sbitmap);
+	return atomic_read(&hctx->nr_active);
+}
+
 static inline void __blk_mq_put_driver_tag(struct blk_mq_hw_ctx *hctx,
 					   struct request *rq)
 {
@@ -210,7 +236,7 @@  static inline void __blk_mq_put_driver_tag(struct blk_mq_hw_ctx *hctx,
 
 	if (rq->rq_flags & RQF_MQ_INFLIGHT) {
 		rq->rq_flags &= ~RQF_MQ_INFLIGHT;
-		atomic_dec(&hctx->nr_active);
+		__blk_mq_dec_active_requests(hctx, rq->q);
 	}
 }
 
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 8fd900998b4e..c536278bec9e 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -488,6 +488,8 @@  struct request_queue {
 	struct timer_list	timeout;
 	struct work_struct	timeout_work;
 
+	atomic_t		nr_active_requests_shared_sbitmap;
+
 	struct list_head	icq_list;
 #ifdef CONFIG_BLK_CGROUP
 	DECLARE_BITMAP		(blkcg_pols, BLKCG_MAX_POLS);