[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>

1 files changed, 2 insertions, 3 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