rbtree: move some implementation details from rbtree.h to rbtree.c

rbtree users must use the documented APIs to manipulate the tree
structure.  Low-level helpers to manipulate node colors and parenthood are
not part of that API, so move them to lib/rbtree.c

[dwmw2@infradead.org: fix jffs2 build issue due to renamed __rb_parent_color field]
Signed-off-by: Michel Lespinasse <walken@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: David Woodhouse <David.Woodhouse@intel.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Daniel Santos <daniel.santos@pobox.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 36 insertions, 31 deletions

diff --git a/fs/jffs2/readinode.c b/fs/jffs2/readinode.c
index 1ea349fff68..ae81b01e6fd 100644
--- a/fs/jffs2/readinode.c
+++ b/fs/jffs2/readinode.c
@@ -394,8 +394,11 @@ static int jffs2_add_tn_to_tree(struct jffs2_sb_info *c,
 }
 
 /* Trivial function to remove the last node in the tree. Which by definition
-   has no right-hand -- so can be removed just by making its only child (if
-   any) take its place under its parent. */
+   has no right-hand child — so can be removed just by making its left-hand
+   child (if any) take its place under its parent. Since this is only done
+   when we're consuming the whole tree, there's no need to use rb_erase()
+   and let it worry about adjusting colours and balancing the tree. That
+   would just be a waste of time. */
 static void eat_last(struct rb_root *root, struct rb_node *node)
 {
         struct rb_node *parent = rb_parent(node);
@@ -412,12 +415,12 @@ static void eat_last(struct rb_root *root, struct rb_node *node)
                 link = &parent->rb_right;
 
         *link = node->rb_left;
-        /* Colour doesn't matter now. Only the parent pointer. */
         if (node->rb_left)
-                node->rb_left->rb_parent_color = node->rb_parent_color;
+                node->rb_left->__rb_parent_color = node->__rb_parent_color;
 }
 
-/* We put this in reverse order, so we can just use eat_last */
+/* We put the version tree in reverse order, so we can use the same eat_last()
+   function that we use to consume the tmpnode tree (tn_root). */
 static void ver_insert(struct rb_root *ver_root, struct jffs2_tmp_dnode_info *tn)
 {
         struct rb_node **link = &ver_root->rb_node;
diff --git a/include/linux/rbtree.h b/include/linux/rbtree.h
index 2049087c43b..bf836a2c6a3 100644
--- a/include/linux/rbtree.h
+++ b/include/linux/rbtree.h
@@ -32,37 +32,19 @@
 #include <linux/kernel.h>
 #include <linux/stddef.h>
 
-struct rb_node
-{
-        unsigned long  rb_parent_color;
-#define RB_RED          0
-#define RB_BLACK        1
+struct rb_node {
+        unsigned long  __rb_parent_color;
         struct rb_node *rb_right;
         struct rb_node *rb_left;
 } __attribute__((aligned(sizeof(long))));
     /* The alignment might seem pointless, but allegedly CRIS needs it */
 
-struct rb_root
-{
+struct rb_root {
         struct rb_node *rb_node;
 };
 
 
-#define rb_parent(r)   ((struct rb_node *)((r)->rb_parent_color & ~3))
-#define rb_color(r)   ((r)->rb_parent_color & 1)
-#define rb_is_red(r)   (!rb_color(r))
-#define rb_is_black(r) rb_color(r)
-#define rb_set_red(r)  do { (r)->rb_parent_color &= ~1; } while (0)
-#define rb_set_black(r)  do { (r)->rb_parent_color |= 1; } while (0)
-
-static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p)
-{
-        rb->rb_parent_color = (rb->rb_parent_color & 3) | (unsigned long)p;
-}
-static inline void rb_set_color(struct rb_node *rb, int color)
-{
-        rb->rb_parent_color = (rb->rb_parent_color & ~1) | color;
-}
+#define rb_parent(r)   ((struct rb_node *)((r)->__rb_parent_color & ~3))
 
 #define RB_ROOT (struct rb_root) { NULL, }
 #define rb_entry(ptr, type, member) container_of(ptr, type, member)
@@ -70,8 +52,10 @@ static inline void rb_set_color(struct rb_node *rb, int color)
 #define RB_EMPTY_ROOT(root)  ((root)->rb_node == NULL)
 
 /* 'empty' nodes are nodes that are known not to be inserted in an rbree */
-#define RB_EMPTY_NODE(node)  ((node)->rb_parent_color == (unsigned long)(node))
-#define RB_CLEAR_NODE(node)  ((node)->rb_parent_color = (unsigned long)(node))
+#define RB_EMPTY_NODE(node)  \
+        ((node)->__rb_parent_color == (unsigned long)(node))
+#define RB_CLEAR_NODE(node)  \
+        ((node)->__rb_parent_color = (unsigned long)(node))
 
 
 extern void rb_insert_color(struct rb_node *, struct rb_root *);
@@ -98,7 +82,7 @@ extern void rb_replace_node(struct rb_node *victim, struct rb_node *new,
 static inline void rb_link_node(struct rb_node * node, struct rb_node * parent,
                                 struct rb_node ** rb_link)
 {
-        node->rb_parent_color = (unsigned long )parent;
+        node->__rb_parent_color = (unsigned long)parent;
         node->rb_left = node->rb_right = NULL;
 
         *rb_link = node;
diff --git a/lib/rbtree.c b/lib/rbtree.c
index fe43c8c5f52..ccada9abe6f 100644
--- a/lib/rbtree.c
+++ b/lib/rbtree.c
@@ -23,6 +23,24 @@
 #include <linux/rbtree.h>
 #include <linux/export.h>
 
+#define RB_RED          0
+#define RB_BLACK        1
+
+#define rb_color(r)   ((r)->__rb_parent_color & 1)
+#define rb_is_red(r)   (!rb_color(r))
+#define rb_is_black(r) rb_color(r)
+#define rb_set_red(r)  do { (r)->__rb_parent_color &= ~1; } while (0)
+#define rb_set_black(r)  do { (r)->__rb_parent_color |= 1; } while (0)
+
+static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p)
+{
+        rb->__rb_parent_color = rb_color(rb) | (unsigned long)p;
+}
+static inline void rb_set_color(struct rb_node *rb, int color)
+{
+        rb->__rb_parent_color = (rb->__rb_parent_color & ~1) | color;
+}
+
 static void __rb_rotate_left(struct rb_node *node, struct rb_root *root)
 {
         struct rb_node *right = node->rb_right;
@@ -255,7 +273,7 @@ void rb_erase(struct rb_node *node, struct rb_root *root)
                         rb_set_parent(old->rb_right, node);
                 }
 
-                node->rb_parent_color = old->rb_parent_color;
+                node->__rb_parent_color = old->__rb_parent_color;
                 node->rb_left = old->rb_left;
                 rb_set_parent(old->rb_left, node);