cfq-iosched: add symmetric reference wrappers

Can you sanity check this before I send it out?

The cfq_group and cfq_queue objects did not have symmetric wrapper functions and many of the reference taking was open coded. For clarity add the following wrappers:

cfq_group:
- cfq_get_group_ref()
- cfq_put_group_ref()

cfq_queue:
- cfq_get_queue_ref()
- cfq_put_queue_ref()

The use of '_ref' was done not to collide with existing function names.

Signed-off-by Justin TerAvest <[email protected]>

---
 block/cfq-iosched.c |   95 +++++++++++++++++++++++++++++---------------------

 1 files changed, 55 insertions(+), 40 deletions(-)

block/cfq-iosched.c +28 -20

index 89e0d1c..e3136d7 100644
@@ -301,6 +301,11 @@ struct cfq_data {
        struct rcu_head rcu;
  };
 
+static void cfq_get_group_ref(struct cfq_group *cfqg);
+static void cfq_put_group_ref(struct cfq_group *cfqg);
+static void cfq_get_queue_ref(struct cfq_queue *cfqq);
+static void cfq_put_queue_ref(struct cfq_queue *cfqq);
+
  static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd);
 
  static struct cfq_rb_root *service_tree_for(struct cfq_group *cfqg,

@@ -1019,7 +1024,7 @@ cfq_find_alloc_cfqg(struct cfq_data *cfqd, struct cgroup *cgroup, int create)
         * elevator which will be dropped by either elevator exit
         * or cgroup deletion path depending on who is exiting first.
         */
-       cfqg->ref = 1;
+       cfq_get_group_ref(cfqg);
 
        /*
         * Add group onto cgroup list. It might happen that bdi->dev is

@@ -1062,24 +1067,12 @@ static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create)
        return cfqg;
  }
 
-static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg)
+static void cfq_get_group_ref(struct cfq_group *cfqg)
  {
        cfqg->ref++;
-       return cfqg;
  }
 
-static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg)
-{
-       /* Currently, all async queues are mapped to root group */
-       if (!cfq_cfqq_sync(cfqq))
-               cfqg = &cfqq->cfqd->root_group;
-
-       cfqq->cfqg = cfqg;
-       /* cfqq reference on cfqg */
-       cfqq->cfqg->ref++;
-}
-
-static void cfq_put_cfqg(struct cfq_group *cfqg)
+static void cfq_put_group_ref(struct cfq_group *cfqg)
  {
        struct cfq_rb_root *st;
        int i, j;

@@ -1093,6 +1086,17 @@ static void cfq_put_cfqg(struct cfq_group *cfqg)
        kfree(cfqg);
  }
 
+static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg)
+{
+       /* Currently, all async queues are mapped to root group */
+       if (!cfq_cfqq_sync(cfqq))
+               cfqg = &cfqq->cfqd->root_group;
+
+       cfqq->cfqg = cfqg;
+       /* cfqq reference on cfqg */
+       cfq_get_group_ref(cfqq->cfqg);
+}
+
  static void cfq_destroy_cfqg(struct cfq_data *cfqd, struct cfq_group *cfqg)
  {
        /* Something wrong if we are trying to remove same group twice */

@@ -1104,7 +1108,7 @@ static void cfq_destroy_cfqg(struct cfq_data *cfqd, struct cfq_group *cfqg)
         * Put the reference taken at the time of creation so that when all
         * queues are gone, group can be destroyed.
         */
-       cfq_put_cfqg(cfqg);
+       cfq_put_group_ref(cfqg);
  }
 
  static void cfq_release_cfq_groups(struct cfq_data *cfqd)

@@ -1148,14 +1152,18 @@ void cfq_unlink_blkio_group(void *key, struct blkio_group *blkg)
  }
 
  #else /* GROUP_IOSCHED */
-static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create)
+
+static void cfq_get_group_ref(struct cfq_group *cfqg)
  {
-       return &cfqd->root_group;
  }
 
-static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg)
+static void cfq_put_group_ref(struct cfq_group *cfqg)
  {
-       return cfqg;
+}
+
+static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create)
+{
+       return &cfqd->root_group;
  }
 

 static inline void

block/cfq-iosched.c +27 -21

@@ -1164,7 +1172,6 @@ cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) {
  }
 
  static void cfq_release_cfq_groups(struct cfq_data *cfqd) {}
-static inline void cfq_put_cfqg(struct cfq_group *cfqg) {}
 
  #endif /* GROUP_IOSCHED */
 

@@ -2524,6 +2531,11 @@ static int cfq_dispatch_requests(struct request_queue *q, int force)
        return 1;
  }
 
+static void cfq_get_queue_ref(struct cfq_queue *cfqq)
+{
+       cfqq->ref++;
+}
+
  /*
  * task holds one reference to the queue, dropped when task exits. each rq
  * in-flight on this queue also holds a reference, dropped when rq is freed.

@@ -2531,7 +2543,7 @@ static int cfq_dispatch_requests(struct request_queue *q, int force)
  * Each cfq queue took a reference on the parent group. Drop it now.
  * queue lock must be held here.
  */
-static void cfq_put_queue(struct cfq_queue *cfqq)
+static void cfq_put_queue_ref(struct cfq_queue *cfqq)
  {
        struct cfq_data *cfqd = cfqq->cfqd;
        struct cfq_group *cfqg;

@@ -2554,7 +2566,7 @@ static void cfq_put_queue(struct cfq_queue *cfqq)
 
        BUG_ON(cfq_cfqq_on_rr(cfqq));
        kmem_cache_free(cfq_pool, cfqq);
-       cfq_put_cfqg(cfqg);
+       cfq_put_group_ref(cfqg);
  }
 
  /*

@@ -2659,7 +2671,7 @@ static void cfq_put_cooperator(struct cfq_queue *cfqq)
                        break;
                }
                next = __cfqq->new_cfqq;
-               cfq_put_queue(__cfqq);
+               cfq_put_queue_ref(__cfqq);
                __cfqq = next;
        }
  }

@@ -2673,7 +2685,7 @@ static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 
        cfq_put_cooperator(cfqq);
 
-       cfq_put_queue(cfqq);
+       cfq_put_queue_ref(cfqq);
  }
 
  static void __cfq_exit_single_io_context(struct cfq_data *cfqd,

@@ -2815,7 +2827,7 @@ static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic)
                                                GFP_ATOMIC);
                if (new_cfqq) {
                        cic->cfqq[BLK_RW_ASYNC] = new_cfqq;
-                       cfq_put_queue(cfqq);
+                       cfq_put_queue_ref(cfqq);
                }
        }
 

@@ -2874,7 +2886,7 @@ static void changed_cgroup(struct io_context *ioc, struct cfq_io_context *cic)
                 */
                cfq_log_cfqq(cfqd, sync_cfqq, "changed cgroup");
                cic_set_cfqq(cic, NULL, 1);
-               cfq_put_queue(sync_cfqq);
+               cfq_put_queue_ref(sync_cfqq);
        }
 
        spin_unlock_irqrestore(q->queue_lock, flags);

@@ -2975,11 +2987,11 @@ cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct io_context *ioc,
         * pin the queue now that it's allocated, scheduler exit will prune it
         */
        if (!is_sync && !(*async_cfqq)) {
-               cfqq->ref++;
+               cfq_get_queue_ref(cfqq);
                *async_cfqq = cfqq;
        }
 
-       cfqq->ref++;
+       cfq_get_queue_ref(cfqq);
        return cfqq;
  }
 

@@ -3604,10 +3616,10 @@ static void cfq_put_request(struct request *rq)
                rq->elevator_private[1] = NULL;
 
                /* Put down rq reference on cfqg */
-               cfq_put_cfqg(RQ_CFQG(rq));
+               cfq_put_group_ref(RQ_CFQG(rq));
                rq->elevator_private[2] = NULL;
 
-               cfq_put_queue(cfqq);
+               cfq_put_queue_ref(cfqq);
        }
  }
 

@@ -3618,7 +3630,7 @@ cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_context *cic,
        cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq);
        cic_set_cfqq(cic, cfqq->new_cfqq, 1);
        cfq_mark_cfqq_coop(cfqq->new_cfqq);
-       cfq_put_queue(cfqq);
+       cfq_put_queue_ref(cfqq);
        return cic_to_cfqq(cic, 1);
  }
 

@@ -3640,7 +3652,7 @@ split_cfqq(struct cfq_io_context *cic, struct cfq_queue *cfqq)
 
        cfq_put_cooperator(cfqq);
 
-       cfq_put_queue(cfqq);
+       cfq_put_queue_ref(cfqq);
        return NULL;
  }
  /*

@@ -3693,10 +3705,12 @@ new_queue:
 
        cfqq->allocated[rw]++;
 
-       cfqq->ref++;
+       cfq_get_queue_ref(cfqq);
        rq->elevator_private[0] = cic;
        rq->elevator_private[1] = cfqq;
-       rq->elevator_private[2] = cfq_ref_get_cfqg(cfqq->cfqg);
+
+       cfq_get_group_ref(cfqq->cfqg);
+       rq->elevator_private[2] = cfqq->cfqg;
        spin_unlock_irqrestore(q->queue_lock, flags);
        return 0;
 

@@ -3789,13 +3803,13 @@ static void cfq_put_async_queues(struct cfq_data *cfqd)
 
        for (i = 0; i < IOPRIO_BE_NR; i++) {
                if (cfqd->async_cfqq[0][i])
-                       cfq_put_queue(cfqd->async_cfqq[0][i]);
+                       cfq_put_queue_ref(cfqd->async_cfqq[0][i]);
                if (cfqd->async_cfqq[1][i])
-                       cfq_put_queue(cfqd->async_cfqq[1][i]);
+                       cfq_put_queue_ref(cfqd->async_cfqq[1][i]);
        }
 
        if (cfqd->async_idle_cfqq)
-               cfq_put_queue(cfqd->async_idle_cfqq);
+               cfq_put_queue_ref(cfqd->async_idle_cfqq);
  }
 
  static void cfq_cfqd_free(struct rcu_head *head)

@@ -3893,9 +3907,10 @@ static void *cfq_init_queue(struct request_queue *q)
  #ifdef CONFIG_CFQ_GROUP_IOSCHED
        /*
         * Take a reference to root group which we never drop. This is just
-        * to make sure that cfq_put_cfqg() does not try to kfree root group
+        * to make sure that cfq_put_group_ref() does not try to kfree
+        * root group
         */
-       cfqg->ref = 1;
+       cfq_get_group_ref(cfqg);
        rcu_read_lock();
        cfq_blkiocg_add_blkio_group(&blkio_root_cgroup, &cfqg->blkg,
                                        (void *)cfqd, 0);
--

1.7.3.1