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>

diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 252a81a..fa9a900 100644 (file)
--- 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;