blk-throttle: Do the new group initialization with the help of a function

Group initialization code seems to be at two places. root group
initialization in blk_throtl_init() and dynamically allocated group
in throtl_find_alloc_tg(). Create a common function and use at both
the places.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

1 files changed, 35 insertions, 29 deletions

diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 252a81a306f7..fa9a900c1254 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -159,6 +159,35 @@ static void throtl_put_tg(struct throtl_grp *tg)
         kfree(tg);
 }
 
+static void throtl_init_group(struct throtl_grp *tg)
+{
+        INIT_HLIST_NODE(&tg->tg_node);
+        RB_CLEAR_NODE(&tg->rb_node);
+        bio_list_init(&tg->bio_lists[0]);
+        bio_list_init(&tg->bio_lists[1]);
+        tg->limits_changed = false;
+
+        /* Practically unlimited BW */
+        tg->bps[0] = tg->bps[1] = -1;
+        tg->iops[0] = tg->iops[1] = -1;
+
+        /*
+         * Take the initial reference that will be released on destroy
+         * This can be thought of a joint reference by cgroup and
+         * request queue which will be dropped by either request queue
+         * exit or cgroup deletion path depending on who is exiting first.
+         */
+        atomic_set(&tg->ref, 1);
+}
+
+/* Should be called with rcu read lock held (needed for blkcg) */
+static void
+throtl_add_group_to_td_list(struct throtl_data *td, struct throtl_grp *tg)
+{
+        hlist_add_head(&tg->tg_node, &td->tg_list);
+        td->nr_undestroyed_grps++;
+}
+
 static struct throtl_grp * throtl_find_alloc_tg(struct throtl_data *td,
                         struct blkio_cgroup *blkcg)
 {
@@ -196,19 +225,7 @@ static struct throtl_grp * throtl_find_alloc_tg(struct throtl_data *td,
         if (!tg)
                 goto done;
 
-        INIT_HLIST_NODE(&tg->tg_node);
-        RB_CLEAR_NODE(&tg->rb_node);
-        bio_list_init(&tg->bio_lists[0]);
-        bio_list_init(&tg->bio_lists[1]);
-        td->limits_changed = false;
-
-        /*
-         * Take the initial reference that will be released on destroy
-         * This can be thought of a joint reference by cgroup and
-         * request queue which will be dropped by either request queue
-         * exit or cgroup deletion path depending on who is exiting first.
-         */
-        atomic_set(&tg->ref, 1);
+        throtl_init_group(tg);
 
         /* Add group onto cgroup list */
         sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
@@ -220,8 +237,7 @@ static struct throtl_grp * throtl_find_alloc_tg(struct throtl_data *td,
         tg->iops[READ] = blkcg_get_read_iops(blkcg, tg->blkg.dev);
         tg->iops[WRITE] = blkcg_get_write_iops(blkcg, tg->blkg.dev);
 
-        hlist_add_head(&tg->tg_node, &td->tg_list);
-        td->nr_undestroyed_grps++;
+        throtl_add_group_to_td_list(td, tg);
 done:
         return tg;
 }
@@ -1060,18 +1076,11 @@ int blk_throtl_init(struct request_queue *q)
         INIT_HLIST_HEAD(&td->tg_list);
         td->tg_service_tree = THROTL_RB_ROOT;
         td->limits_changed = false;
+        INIT_DELAYED_WORK(&td->throtl_work, blk_throtl_work);
 
         /* Init root group */
         tg = &td->root_tg;
-        INIT_HLIST_NODE(&tg->tg_node);
-        RB_CLEAR_NODE(&tg->rb_node);
-        bio_list_init(&tg->bio_lists[0]);
-        bio_list_init(&tg->bio_lists[1]);
-
-        /* Practically unlimited BW */
-        tg->bps[0] = tg->bps[1] = -1;
-        tg->iops[0] = tg->iops[1] = -1;
-        td->limits_changed = false;
+        throtl_init_group(tg);
 
         /*
          * Set root group reference to 2. One reference will be dropped when
@@ -1080,16 +1089,13 @@ int blk_throtl_init(struct request_queue *q)
          * as it is statically allocated and gets destroyed when throtl_data
          * goes away.
          */
-        atomic_set(&tg->ref, 2);
-        hlist_add_head(&tg->tg_node, &td->tg_list);
-        td->nr_undestroyed_grps++;
-
-        INIT_DELAYED_WORK(&td->throtl_work, blk_throtl_work);
+        atomic_inc(&tg->ref);
 
         rcu_read_lock();
         blkiocg_add_blkio_group(&blkio_root_cgroup, &tg->blkg, (void *)td,
                                         0, BLKIO_POLICY_THROTL);
         rcu_read_unlock();
+        throtl_add_group_to_td_list(td, tg);
 
         /* Attach throtl data to request queue */
         td->queue = q;