[PATCH 2/3] bfq: Track number of allocated requests in bfq_entity

[Jan Kara <jack@suse.cz>]

When we want to limit number of requests used by each bfqq and also
cgroup, we need to track also number of requests used by each cgroup.
So track number of allocated requests for each bfq_entity.

Signed-off-by: Jan Kara <jack@suse.cz>
---
 block/bfq-iosched.c | 28 ++++++++++++++++++++++------
 block/bfq-iosched.h |  5 +++--
 2 files changed, 25 insertions(+), 8 deletions(-)

diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 727955918563..9ef057dc0028 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -1113,7 +1113,8 @@ bfq_bfqq_resume_state(struct bfq_queue *bfqq, struct bfq_data *bfqd,
 
 static int bfqq_process_refs(struct bfq_queue *bfqq)
 {
-	return bfqq->ref - bfqq->allocated - bfqq->entity.on_st_or_in_serv -
+	return bfqq->ref - bfqq->entity.allocated -
+		bfqq->entity.on_st_or_in_serv -
 		(bfqq->weight_counter != NULL) - bfqq->stable_ref;
 }
 
@@ -5875,6 +5876,22 @@ static void bfq_rq_enqueued(struct bfq_data *bfqd, struct bfq_queue *bfqq,
 	}
 }
 
+static void bfqq_request_allocated(struct bfq_queue *bfqq)
+{
+	struct bfq_entity *entity = &bfqq->entity;
+
+	for_each_entity(entity)
+		entity->allocated++;
+}
+
+static void bfqq_request_freed(struct bfq_queue *bfqq)
+{
+	struct bfq_entity *entity = &bfqq->entity;
+
+	for_each_entity(entity)
+		entity->allocated--;
+}
+
 /* returns true if it causes the idle timer to be disabled */
 static bool __bfq_insert_request(struct bfq_data *bfqd, struct request *rq)
 {
@@ -5888,8 +5905,8 @@ static bool __bfq_insert_request(struct bfq_data *bfqd, struct request *rq)
 		 * Release the request's reference to the old bfqq
 		 * and make sure one is taken to the shared queue.
 		 */
-		new_bfqq->allocated++;
-		bfqq->allocated--;
+		bfqq_request_allocated(new_bfqq);
+		bfqq_request_freed(bfqq);
 		new_bfqq->ref++;
 		/*
 		 * If the bic associated with the process
@@ -6248,8 +6265,7 @@ static void bfq_completed_request(struct bfq_queue *bfqq, struct bfq_data *bfqd)
 
 static void bfq_finish_requeue_request_body(struct bfq_queue *bfqq)
 {
-	bfqq->allocated--;
-
+	bfqq_request_freed(bfqq);
 	bfq_put_queue(bfqq);
 }
 
@@ -6669,7 +6685,7 @@ static struct bfq_queue *bfq_init_rq(struct request *rq)
 		}
 	}
 
-	bfqq->allocated++;
+	bfqq_request_allocated(bfqq);
 	bfqq->ref++;
 	bfq_log_bfqq(bfqd, bfqq, "get_request %p: bfqq %p, %d",
 		     rq, bfqq, bfqq->ref);
diff --git a/block/bfq-iosched.h b/block/bfq-iosched.h
index 99c2a3cb081e..70d4a9b54613 100644
--- a/block/bfq-iosched.h
+++ b/block/bfq-iosched.h
@@ -170,6 +170,9 @@ struct bfq_entity {
 	/* budget, used also to calculate F_i: F_i = S_i + @budget / @weight */
 	int budget;
 
+	/* Number of requests allocated in the subtree of this entity */
+	int allocated;
+
 	/* device weight, if non-zero, it overrides the default weight of
 	 * bfq_group_data */
 	int dev_weight;
@@ -266,8 +269,6 @@ struct bfq_queue {
 	struct request *next_rq;
 	/* number of sync and async requests queued */
 	int queued[2];
-	/* number of requests currently allocated */
-	int allocated;
 	/* number of pending metadata requests */
 	int meta_pending;
 	/* fifo list of requests in sort_list */
-- 
2.26.2