[RBTREE] Change rbtree off-tree marking in I/O schedulers.

They were abusing the rb_color field to mark nodes which weren't currently
on the tree. Fix that to use the same method as eventpoll did -- setting
the parent pointer to point back to itself. And use the appropriate
accessor macros for setting and reading the parent.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>

3 files changed, 5 insertions, 13 deletions

diff --git a/block/as-iosched.c b/block/as-iosched.c
index e25a5d79ab27..ed336ab453ba 100644
--- a/block/as-iosched.c
+++ b/block/as-iosched.c
@@ -353,10 +353,9 @@ static struct request *as_find_arq_hash(struct as_data *ad, sector_t offset)
 /*
  * rb tree support functions
  */
-#define RB_NONE         (2)
 #define RB_EMPTY(root)  ((root)->rb_node == NULL)
-#define ON_RB(node)     ((node)->rb_color != RB_NONE)
-#define RB_CLEAR(node)  ((node)->rb_color = RB_NONE)
+#define ON_RB(node)     (rb_parent(node) != node)
+#define RB_CLEAR(node)  (rb_set_parent(node, node))
 #define rb_entry_arq(node)      rb_entry((node), struct as_rq, rb_node)
 #define ARQ_RB_ROOT(ad, arq)    (&(ad)->sort_list[(arq)->is_sync])
 #define rq_rb_key(rq)           (rq)->sector
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 2540dfaa3e38..01c416ba8437 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -60,14 +60,9 @@ static DEFINE_RWLOCK(cfq_exit_lock);
 /*
  * rb-tree defines
  */
-#define RB_NONE                 (2)
 #define RB_EMPTY(node)          ((node)->rb_node == NULL)
-#define RB_CLEAR_COLOR(node)    (node)->rb_color = RB_NONE
 #define RB_CLEAR(node)          do {    \
-        (node)->rb_parent = NULL;       \
-        RB_CLEAR_COLOR((node));         \
-        (node)->rb_right = NULL;        \
-        (node)->rb_left = NULL;         \
+                memset(node, 0, sizeof(*node)); \
 } while (0)
 #define RB_CLEAR_ROOT(root)     ((root)->rb_node = NULL)
 #define rb_entry_crq(node)      rb_entry((node), struct cfq_rq, rb_node)
@@ -563,7 +558,6 @@ static inline void cfq_del_crq_rb(struct cfq_rq *crq)
         cfq_update_next_crq(crq);
 
         rb_erase(&crq->rb_node, &cfqq->sort_list);
-        RB_CLEAR_COLOR(&crq->rb_node);
 
         if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY(&cfqq->sort_list))
                 cfq_del_cfqq_rr(cfqd, cfqq);
diff --git a/block/deadline-iosched.c b/block/deadline-iosched.c
index 399fa1e60e1f..06962d8402a3 100644
--- a/block/deadline-iosched.c
+++ b/block/deadline-iosched.c
@@ -165,10 +165,9 @@ deadline_find_drq_hash(struct deadline_data *dd, sector_t offset)
 /*
  * rb tree support functions
  */
-#define RB_NONE         (2)
 #define RB_EMPTY(root)  ((root)->rb_node == NULL)
-#define ON_RB(node)     ((node)->rb_color != RB_NONE)
-#define RB_CLEAR(node)  ((node)->rb_color = RB_NONE)
+#define ON_RB(node)     (rb_parent(node) != node)
+#define RB_CLEAR(node)  (rb_set_parent(node, node))
 #define rb_entry_drq(node)      rb_entry((node), struct deadline_rq, rb_node)
 #define DRQ_RB_ROOT(dd, drq)    (&(dd)->sort_list[rq_data_dir((drq)->request)])
 #define rq_rb_key(rq)           (rq)->sector