Blk-throttle: update to use rbtree with leftmost node cached
As rbtree has native support of caching leftmost node,
i.e. rb_root_cached, no need to do the caching by ourselves.
Signed-off-by: Liu Bo <bo.liu@linux.alibaba.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 01d0620..db1a3a2 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -84,8 +84,7 @@
* RB tree of active children throtl_grp's, which are sorted by
* their ->disptime.
*/
- struct rb_root pending_tree; /* RB tree of active tgs */
- struct rb_node *first_pending; /* first node in the tree */
+ struct rb_root_cached pending_tree; /* RB tree of active tgs */
unsigned int nr_pending; /* # queued in the tree */
unsigned long first_pending_disptime; /* disptime of the first tg */
struct timer_list pending_timer; /* fires on first_pending_disptime */
@@ -475,7 +474,7 @@
{
INIT_LIST_HEAD(&sq->queued[0]);
INIT_LIST_HEAD(&sq->queued[1]);
- sq->pending_tree = RB_ROOT;
+ sq->pending_tree = RB_ROOT_CACHED;
timer_setup(&sq->pending_timer, throtl_pending_timer_fn, 0);
}
@@ -616,31 +615,23 @@
static struct throtl_grp *
throtl_rb_first(struct throtl_service_queue *parent_sq)
{
+ struct rb_node *n;
/* Service tree is empty */
if (!parent_sq->nr_pending)
return NULL;
- if (!parent_sq->first_pending)
- parent_sq->first_pending = rb_first(&parent_sq->pending_tree);
-
- if (parent_sq->first_pending)
- return rb_entry_tg(parent_sq->first_pending);
-
- return NULL;
-}
-
-static void rb_erase_init(struct rb_node *n, struct rb_root *root)
-{
- rb_erase(n, root);
- RB_CLEAR_NODE(n);
+ n = rb_first_cached(&parent_sq->pending_tree);
+ WARN_ON_ONCE(!n);
+ if (!n)
+ return NULL;
+ return rb_entry_tg(n);
}
static void throtl_rb_erase(struct rb_node *n,
struct throtl_service_queue *parent_sq)
{
- if (parent_sq->first_pending == n)
- parent_sq->first_pending = NULL;
- rb_erase_init(n, &parent_sq->pending_tree);
+ rb_erase_cached(n, &parent_sq->pending_tree);
+ RB_CLEAR_NODE(n);
--parent_sq->nr_pending;
}
@@ -658,11 +649,11 @@
static void tg_service_queue_add(struct throtl_grp *tg)
{
struct throtl_service_queue *parent_sq = tg->service_queue.parent_sq;
- struct rb_node **node = &parent_sq->pending_tree.rb_node;
+ struct rb_node **node = &parent_sq->pending_tree.rb_root.rb_node;
struct rb_node *parent = NULL;
struct throtl_grp *__tg;
unsigned long key = tg->disptime;
- int left = 1;
+ bool leftmost = true;
while (*node != NULL) {
parent = *node;
@@ -672,15 +663,13 @@
node = &parent->rb_left;
else {
node = &parent->rb_right;
- left = 0;
+ leftmost = false;
}
}
- if (left)
- parent_sq->first_pending = &tg->rb_node;
-
rb_link_node(&tg->rb_node, parent, node);
- rb_insert_color(&tg->rb_node, &parent_sq->pending_tree);
+ rb_insert_color_cached(&tg->rb_node, &parent_sq->pending_tree,
+ leftmost);
}
static void __throtl_enqueue_tg(struct throtl_grp *tg)