[PATCH 1/8] block: Provide icq in request allocation data

[Jan Kara <jack@suse.cz>]

Currently we lookup ICQ only after the request is allocated. However BFQ
will want to decide how many scheduler tags it allows a given bfq queue
(effectively a process) to consume based on cgroup weight. So lookup ICQ
earlier and provide it in struct blk_mq_alloc_data so that BFQ can use
it.

Acked-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jan Kara <jack@suse.cz>
---
 block/blk-mq-sched.c | 18 ++++++++++--------
 block/blk-mq-sched.h |  3 ++-
 block/blk-mq.c       |  8 ++++----
 block/blk-mq.h       |  1 +
 4 files changed, 17 insertions(+), 13 deletions(-)

diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index ba21449439cc..c4015b82a003 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -18,9 +18,8 @@
 #include "blk-mq-tag.h"
 #include "blk-wbt.h"
 
-void blk_mq_sched_assign_ioc(struct request *rq)
+struct io_cq *blk_mq_sched_lookup_icq(struct request_queue *q)
 {
-	struct request_queue *q = rq->q;
 	struct io_context *ioc;
 	struct io_cq *icq;
 
@@ -29,17 +28,20 @@ void blk_mq_sched_assign_ioc(struct request *rq)
 	 */
 	ioc = current->io_context;
 	if (!ioc)
-		return;
+		return NULL;
 
 	spin_lock_irq(&q->queue_lock);
 	icq = ioc_lookup_icq(ioc, q);
 	spin_unlock_irq(&q->queue_lock);
+	if (icq)
+		return icq;
+	return ioc_create_icq(ioc, q, GFP_ATOMIC);
+}
 
-	if (!icq) {
-		icq = ioc_create_icq(ioc, q, GFP_ATOMIC);
-		if (!icq)
-			return;
-	}
+void blk_mq_sched_assign_ioc(struct request *rq, struct io_cq *icq)
+{
+	if (!icq)
+		return;
 	get_io_context(icq->ioc);
 	rq->elv.icq = icq;
 }
diff --git a/block/blk-mq-sched.h b/block/blk-mq-sched.h
index 25d1034952b6..40be707f69d7 100644
--- a/block/blk-mq-sched.h
+++ b/block/blk-mq-sched.h
@@ -8,7 +8,8 @@
 
 #define MAX_SCHED_RQ (16 * BLKDEV_DEFAULT_RQ)
 
-void blk_mq_sched_assign_ioc(struct request *rq);
+struct io_cq *blk_mq_sched_lookup_icq(struct request_queue *q);
+void blk_mq_sched_assign_ioc(struct request *rq, struct io_cq *icq);
 
 bool blk_mq_sched_try_merge(struct request_queue *q, struct bio *bio,
 		unsigned int nr_segs, struct request **merged_request);
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 8799fa73ef34..69b224c76d7c 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -388,9 +388,7 @@ static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data,
 
 		if (!op_is_flush(data->cmd_flags) &&
 		    e->type->ops.prepare_request) {
-			if (e->type->icq_cache)
-				blk_mq_sched_assign_ioc(rq);
-
+			blk_mq_sched_assign_ioc(rq, data->icq);
 			e->type->ops.prepare_request(rq);
 			rq->rq_flags |= RQF_ELVPRIV;
 		}
@@ -449,7 +447,9 @@ static struct request *__blk_mq_alloc_requests(struct blk_mq_alloc_data *data)
 		struct elevator_queue *e = q->elevator;
 
 		data->rq_flags |= RQF_ELV;
-
+		if (!op_is_flush(data->cmd_flags) && e->type->icq_cache &&
+		    e->type->ops.prepare_request)
+			data->icq = blk_mq_sched_lookup_icq(q);
 		/*
 		 * Flush/passthrough requests are special and go directly to the
 		 * dispatch list. Don't include reserved tags in the
diff --git a/block/blk-mq.h b/block/blk-mq.h
index afcf9931a489..4e9cf92ca587 100644
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -152,6 +152,7 @@ static inline struct blk_mq_ctx *blk_mq_get_ctx(struct request_queue *q)
 struct blk_mq_alloc_data {
 	/* input parameter */
 	struct request_queue *q;
+	struct io_cq *icq;
 	blk_mq_req_flags_t flags;
 	unsigned int shallow_depth;
 	unsigned int cmd_flags;
-- 
2.26.2