1 files changed, 20 insertions, 14 deletions

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index b0b754a6882b..a55a9bd75bd1 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -154,6 +154,8 @@ struct cfq_queue {
         unsigned long rb_key;
         /* prio tree member */
         struct rb_node p_node;
+        /* prio tree root we belong to, if any */
+        struct rb_root *p_root;
         /* sorted list of pending requests */
         struct rb_root sort_list;
         /* if fifo isn't expired, next request to serve */
@@ -558,10 +560,10 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
 }
 
 static struct cfq_queue *
-cfq_prio_tree_lookup(struct cfq_data *cfqd, int ioprio, sector_t sector,
-                     struct rb_node **ret_parent, struct rb_node ***rb_link)
+cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root,
+                     sector_t sector, struct rb_node **ret_parent,
+                     struct rb_node ***rb_link)
 {
-        struct rb_root *root = &cfqd->prio_trees[ioprio];
         struct rb_node **p, *parent;
         struct cfq_queue *cfqq = NULL;
 
@@ -595,24 +597,27 @@ cfq_prio_tree_lookup(struct cfq_data *cfqd, int ioprio, sector_t sector,
 
 static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 {
-        struct rb_root *root = &cfqd->prio_trees[cfqq->ioprio];
         struct rb_node **p, *parent;
         struct cfq_queue *__cfqq;
 
-        if (!RB_EMPTY_NODE(&cfqq->p_node))
-                rb_erase_init(&cfqq->p_node, root);
+        if (cfqq->p_root) {
+                rb_erase(&cfqq->p_node, cfqq->p_root);
+                cfqq->p_root = NULL;
+        }
 
         if (cfq_class_idle(cfqq))
                 return;
         if (!cfqq->next_rq)
                 return;
 
-        __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->ioprio, cfqq->next_rq->sector,
+        cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
+        __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root, cfqq->next_rq->sector,
                                          &parent, &p);
         if (!__cfqq) {
                 rb_link_node(&cfqq->p_node, parent, p);
-                rb_insert_color(&cfqq->p_node, root);
-        }
+                rb_insert_color(&cfqq->p_node, cfqq->p_root);
+        } else
+                cfqq->p_root = NULL;
 }
 
 /*
@@ -657,8 +662,10 @@ static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 
         if (!RB_EMPTY_NODE(&cfqq->rb_node))
                 cfq_rb_erase(&cfqq->rb_node, &cfqd->service_tree);
-        if (!RB_EMPTY_NODE(&cfqq->p_node))
-                rb_erase_init(&cfqq->p_node, &cfqd->prio_trees[cfqq->ioprio]);
+        if (cfqq->p_root) {
+                rb_erase(&cfqq->p_node, cfqq->p_root);
+                cfqq->p_root = NULL;
+        }
 
         BUG_ON(!cfqd->busy_queues);
         cfqd->busy_queues--;
@@ -965,7 +972,7 @@ static inline int cfq_rq_close(struct cfq_data *cfqd, struct request *rq)
 static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
                                     struct cfq_queue *cur_cfqq)
 {
-        struct rb_root *root = &cfqd->prio_trees[cur_cfqq->ioprio];
+        struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
         struct rb_node *parent, *node;
         struct cfq_queue *__cfqq;
         sector_t sector = cfqd->last_position;
@@ -977,8 +984,7 @@ static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
          * First, if we find a request starting at the end of the last
          * request, choose it.
          */
-        __cfqq = cfq_prio_tree_lookup(cfqd, cur_cfqq->ioprio,
-                                      sector, &parent, NULL);
+        __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
         if (__cfqq)
                 return __cfqq;