Btrfs-progs: update rbtree libs
authorJosef Bacik <jbacik@fb.com>
Fri, 10 Oct 2014 20:57:09 +0000 (16:57 -0400)
committerDavid Sterba <dsterba@suse.cz>
Tue, 14 Oct 2014 08:39:40 +0000 (10:39 +0200)
While debugging a broken fs we were seeing hangs in the rb_erase loops.  The
rbtree was simple and wasn't corrupted so it appeared to be a bug in our rbtree
library.  Updating to the kernels latest rbtree code made the infinite loop go
away, so pull it back.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: David Sterba <dsterba@suse.cz>
kerncompat.h
rbtree.c
rbtree.h
rbtree_augmented.h [new file with mode: 0644]

index 520bc9e..8afadc8 100644 (file)
@@ -345,6 +345,11 @@ struct __una_u64 { __le64 x; } __attribute__((__packed__));
 #define put_unaligned_le64(val,p) (((struct __una_u64 *)(p))->x = cpu_to_le64(val))
 #endif
 
+#ifndef true
+#define true 1
+#define false 0
+#endif
+
 #ifndef noinline
 #define noinline
 #endif
index 6ad800f..92590a5 100644 (file)
--- a/rbtree.c
+++ b/rbtree.c
@@ -2,7 +2,8 @@
   Red Black Trees
   (C) 1999  Andrea Arcangeli <andrea@suse.de>
   (C) 2002  David Woodhouse <dwmw2@infradead.org>
-  
+  (C) 2012  Michel Lespinasse <walken@google.com>
+
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   linux/lib/rbtree.c
 */
 
-#include "rbtree.h"
-
-static void __rb_rotate_left(struct rb_node *node, struct rb_root *root)
-{
-       struct rb_node *right = node->rb_right;
-       struct rb_node *parent = rb_parent(node);
+#include "rbtree_augmented.h"
 
-       if ((node->rb_right = right->rb_left))
-               rb_set_parent(right->rb_left, node);
-       right->rb_left = node;
-
-       rb_set_parent(right, parent);
+/*
+ * red-black trees properties:  http://en.wikipedia.org/wiki/Rbtree
+ *
+ *  1) A node is either red or black
+ *  2) The root is black
+ *  3) All leaves (NULL) are black
+ *  4) Both children of every red node are black
+ *  5) Every simple path from root to leaves contains the same number
+ *     of black nodes.
+ *
+ *  4 and 5 give the O(log n) guarantee, since 4 implies you cannot have two
+ *  consecutive red nodes in a path and every red node is therefore followed by
+ *  a black. So if B is the number of black nodes on every simple path (as per
+ *  5), then the longest possible path due to 4 is 2B.
+ *
+ *  We shall indicate color with case, where black nodes are uppercase and red
+ *  nodes will be lowercase. Unknown color nodes shall be drawn as red within
+ *  parentheses and have some accompanying text comment.
+ */
 
-       if (parent)
-       {
-               if (node == parent->rb_left)
-                       parent->rb_left = right;
-               else
-                       parent->rb_right = right;
-       }
-       else
-               root->rb_node = right;
-       rb_set_parent(node, right);
+static inline void rb_set_black(struct rb_node *rb)
+{
+       rb->__rb_parent_color |= RB_BLACK;
 }
 
-static void __rb_rotate_right(struct rb_node *node, struct rb_root *root)
+static inline struct rb_node *rb_red_parent(struct rb_node *red)
 {
-       struct rb_node *left = node->rb_left;
-       struct rb_node *parent = rb_parent(node);
-
-       if ((node->rb_left = left->rb_right))
-               rb_set_parent(left->rb_right, node);
-       left->rb_right = node;
-
-       rb_set_parent(left, parent);
+       return (struct rb_node *)red->__rb_parent_color;
+}
 
-       if (parent)
-       {
-               if (node == parent->rb_right)
-                       parent->rb_right = left;
-               else
-                       parent->rb_left = left;
-       }
-       else
-               root->rb_node = left;
-       rb_set_parent(node, left);
+/*
+ * Helper function for rotations:
+ * - old's parent and color get assigned to new
+ * - old gets assigned new as a parent and 'color' as a color.
+ */
+static inline void
+__rb_rotate_set_parents(struct rb_node *old, struct rb_node *new,
+                       struct rb_root *root, int color)
+{
+       struct rb_node *parent = rb_parent(old);
+       new->__rb_parent_color = old->__rb_parent_color;
+       rb_set_parent_color(old, new, color);
+       __rb_change_child(old, new, parent, root);
 }
 
-void rb_insert_color(struct rb_node *node, struct rb_root *root)
+static __always_inline void
+__rb_insert(struct rb_node *node, struct rb_root *root,
+           void (*augment_rotate)(struct rb_node *old, struct rb_node *new))
 {
-       struct rb_node *parent, *gparent;
-
-       while ((parent = rb_parent(node)) && rb_is_red(parent))
-       {
-               gparent = rb_parent(parent);
-
-               if (parent == gparent->rb_left)
-               {
-                       {
-                               register struct rb_node *uncle = gparent->rb_right;
-                               if (uncle && rb_is_red(uncle))
-                               {
-                                       rb_set_black(uncle);
-                                       rb_set_black(parent);
-                                       rb_set_red(gparent);
-                                       node = gparent;
-                                       continue;
-                               }
+       struct rb_node *parent = rb_red_parent(node), *gparent, *tmp;
+
+       while (true) {
+               /*
+                * Loop invariant: node is red
+                *
+                * If there is a black parent, we are done.
+                * Otherwise, take some corrective action as we don't
+                * want a red root or two consecutive red nodes.
+                */
+               if (!parent) {
+                       rb_set_parent_color(node, NULL, RB_BLACK);
+                       break;
+               } else if (rb_is_black(parent))
+                       break;
+
+               gparent = rb_red_parent(parent);
+
+               tmp = gparent->rb_right;
+               if (parent != tmp) {    /* parent == gparent->rb_left */
+                       if (tmp && rb_is_red(tmp)) {
+                               /*
+                                * Case 1 - color flips
+                                *
+                                *       G            g
+                                *      / \          / \
+                                *     p   u  -->   P   U
+                                *    /            /
+                                *   n            n
+                                *
+                                * However, since g's parent might be red, and
+                                * 4) does not allow this, we need to recurse
+                                * at g.
+                                */
+                               rb_set_parent_color(tmp, gparent, RB_BLACK);
+                               rb_set_parent_color(parent, gparent, RB_BLACK);
+                               node = gparent;
+                               parent = rb_parent(node);
+                               rb_set_parent_color(node, parent, RB_RED);
+                               continue;
                        }
 
-                       if (parent->rb_right == node)
-                       {
-                               register struct rb_node *tmp;
-                               __rb_rotate_left(parent, root);
-                               tmp = parent;
+                       tmp = parent->rb_right;
+                       if (node == tmp) {
+                               /*
+                                * Case 2 - left rotate at parent
+                                *
+                                *      G             G
+                                *     / \           / \
+                                *    p   U  -->    n   U
+                                *     \           /
+                                *      n         p
+                                *
+                                * This still leaves us in violation of 4), the
+                                * continuation into Case 3 will fix that.
+                                */
+                               parent->rb_right = tmp = node->rb_left;
+                               node->rb_left = parent;
+                               if (tmp)
+                                       rb_set_parent_color(tmp, parent,
+                                                           RB_BLACK);
+                               rb_set_parent_color(parent, node, RB_RED);
+                               augment_rotate(parent, node);
                                parent = node;
-                               node = tmp;
+                               tmp = node->rb_right;
                        }
 
-                       rb_set_black(parent);
-                       rb_set_red(gparent);
-                       __rb_rotate_right(gparent, root);
+                       /*
+                        * Case 3 - right rotate at gparent
+                        *
+                        *        G           P
+                        *       / \         / \
+                        *      p   U  -->  n   g
+                        *     /                 \
+                        *    n                   U
+                        */
+                       gparent->rb_left = tmp;  /* == parent->rb_right */
+                       parent->rb_right = gparent;
+                       if (tmp)
+                               rb_set_parent_color(tmp, gparent, RB_BLACK);
+                       __rb_rotate_set_parents(gparent, parent, root, RB_RED);
+                       augment_rotate(gparent, parent);
+                       break;
                } else {
-                       {
-                               register struct rb_node *uncle = gparent->rb_left;
-                               if (uncle && rb_is_red(uncle))
-                               {
-                                       rb_set_black(uncle);
-                                       rb_set_black(parent);
-                                       rb_set_red(gparent);
-                                       node = gparent;
-                                       continue;
-                               }
+                       tmp = gparent->rb_left;
+                       if (tmp && rb_is_red(tmp)) {
+                               /* Case 1 - color flips */
+                               rb_set_parent_color(tmp, gparent, RB_BLACK);
+                               rb_set_parent_color(parent, gparent, RB_BLACK);
+                               node = gparent;
+                               parent = rb_parent(node);
+                               rb_set_parent_color(node, parent, RB_RED);
+                               continue;
                        }
 
-                       if (parent->rb_left == node)
-                       {
-                               register struct rb_node *tmp;
-                               __rb_rotate_right(parent, root);
-                               tmp = parent;
+                       tmp = parent->rb_left;
+                       if (node == tmp) {
+                               /* Case 2 - right rotate at parent */
+                               parent->rb_left = tmp = node->rb_right;
+                               node->rb_right = parent;
+                               if (tmp)
+                                       rb_set_parent_color(tmp, parent,
+                                                           RB_BLACK);
+                               rb_set_parent_color(parent, node, RB_RED);
+                               augment_rotate(parent, node);
                                parent = node;
-                               node = tmp;
+                               tmp = node->rb_left;
                        }
 
-                       rb_set_black(parent);
-                       rb_set_red(gparent);
-                       __rb_rotate_left(gparent, root);
+                       /* Case 3 - left rotate at gparent */
+                       gparent->rb_right = tmp;  /* == parent->rb_left */
+                       parent->rb_left = gparent;
+                       if (tmp)
+                               rb_set_parent_color(tmp, gparent, RB_BLACK);
+                       __rb_rotate_set_parents(gparent, parent, root, RB_RED);
+                       augment_rotate(gparent, parent);
+                       break;
                }
        }
-
-       rb_set_black(root->rb_node);
 }
 
-static void __rb_erase_color(struct rb_node *node, struct rb_node *parent,
-                            struct rb_root *root)
+/*
+ * Inline version for rb_erase() use - we want to be able to inline
+ * and eliminate the dummy_rotate callback there
+ */
+static __always_inline void
+____rb_erase_color(struct rb_node *parent, struct rb_root *root,
+       void (*augment_rotate)(struct rb_node *old, struct rb_node *new))
 {
-       struct rb_node *other;
-
-       while ((!node || rb_is_black(node)) && node != root->rb_node)
-       {
-               if (parent->rb_left == node)
-               {
-                       other = parent->rb_right;
-                       if (rb_is_red(other))
-                       {
-                               rb_set_black(other);
-                               rb_set_red(parent);
-                               __rb_rotate_left(parent, root);
-                               other = parent->rb_right;
-                       }
-                       if ((!other->rb_left || rb_is_black(other->rb_left)) &&
-                           (!other->rb_right || rb_is_black(other->rb_right)))
-                       {
-                               rb_set_red(other);
-                               node = parent;
-                               parent = rb_parent(node);
+       struct rb_node *node = NULL, *sibling, *tmp1, *tmp2;
+
+       while (true) {
+               /*
+                * Loop invariants:
+                * - node is black (or NULL on first iteration)
+                * - node is not the root (parent is not NULL)
+                * - All leaf paths going through parent and node have a
+                *   black node count that is 1 lower than other leaf paths.
+                */
+               sibling = parent->rb_right;
+               if (node != sibling) {  /* node == parent->rb_left */
+                       if (rb_is_red(sibling)) {
+                               /*
+                                * Case 1 - left rotate at parent
+                                *
+                                *     P               S
+                                *    / \             / \
+                                *   N   s    -->    p   Sr
+                                *      / \         / \
+                                *     Sl  Sr      N   Sl
+                                */
+                               parent->rb_right = tmp1 = sibling->rb_left;
+                               sibling->rb_left = parent;
+                               rb_set_parent_color(tmp1, parent, RB_BLACK);
+                               __rb_rotate_set_parents(parent, sibling, root,
+                                                       RB_RED);
+                               augment_rotate(parent, sibling);
+                               sibling = tmp1;
                        }
-                       else
-                       {
-                               if (!other->rb_right || rb_is_black(other->rb_right))
-                               {
-                                       struct rb_node *o_left;
-                                       if ((o_left = other->rb_left))
-                                               rb_set_black(o_left);
-                                       rb_set_red(other);
-                                       __rb_rotate_right(other, root);
-                                       other = parent->rb_right;
+                       tmp1 = sibling->rb_right;
+                       if (!tmp1 || rb_is_black(tmp1)) {
+                               tmp2 = sibling->rb_left;
+                               if (!tmp2 || rb_is_black(tmp2)) {
+                                       /*
+                                        * Case 2 - sibling color flip
+                                        * (p could be either color here)
+                                        *
+                                        *    (p)           (p)
+                                        *    / \           / \
+                                        *   N   S    -->  N   s
+                                        *      / \           / \
+                                        *     Sl  Sr        Sl  Sr
+                                        *
+                                        * This leaves us violating 5) which
+                                        * can be fixed by flipping p to black
+                                        * if it was red, or by recursing at p.
+                                        * p is red when coming from Case 1.
+                                        */
+                                       rb_set_parent_color(sibling, parent,
+                                                           RB_RED);
+                                       if (rb_is_red(parent))
+                                               rb_set_black(parent);
+                                       else {
+                                               node = parent;
+                                               parent = rb_parent(node);
+                                               if (parent)
+                                                       continue;
+                                       }
+                                       break;
                                }
-                               rb_set_color(other, rb_color(parent));
-                               rb_set_black(parent);
-                               if (other->rb_right)
-                                       rb_set_black(other->rb_right);
-                               __rb_rotate_left(parent, root);
-                               node = root->rb_node;
-                               break;
+                               /*
+                                * Case 3 - right rotate at sibling
+                                * (p could be either color here)
+                                *
+                                *   (p)           (p)
+                                *   / \           / \
+                                *  N   S    -->  N   Sl
+                                *     / \             \
+                                *    sl  Sr            s
+                                *                       \
+                                *                        Sr
+                                */
+                               sibling->rb_left = tmp1 = tmp2->rb_right;
+                               tmp2->rb_right = sibling;
+                               parent->rb_right = tmp2;
+                               if (tmp1)
+                                       rb_set_parent_color(tmp1, sibling,
+                                                           RB_BLACK);
+                               augment_rotate(sibling, tmp2);
+                               tmp1 = sibling;
+                               sibling = tmp2;
                        }
-               }
-               else
-               {
-                       other = parent->rb_left;
-                       if (rb_is_red(other))
-                       {
-                               rb_set_black(other);
-                               rb_set_red(parent);
-                               __rb_rotate_right(parent, root);
-                               other = parent->rb_left;
-                       }
-                       if ((!other->rb_left || rb_is_black(other->rb_left)) &&
-                           (!other->rb_right || rb_is_black(other->rb_right)))
-                       {
-                               rb_set_red(other);
-                               node = parent;
-                               parent = rb_parent(node);
+                       /*
+                        * Case 4 - left rotate at parent + color flips
+                        * (p and sl could be either color here.
+                        *  After rotation, p becomes black, s acquires
+                        *  p's color, and sl keeps its color)
+                        *
+                        *      (p)             (s)
+                        *      / \             / \
+                        *     N   S     -->   P   Sr
+                        *        / \         / \
+                        *      (sl) sr      N  (sl)
+                        */
+                       parent->rb_right = tmp2 = sibling->rb_left;
+                       sibling->rb_left = parent;
+                       rb_set_parent_color(tmp1, sibling, RB_BLACK);
+                       if (tmp2)
+                               rb_set_parent(tmp2, parent);
+                       __rb_rotate_set_parents(parent, sibling, root,
+                                               RB_BLACK);
+                       augment_rotate(parent, sibling);
+                       break;
+               } else {
+                       sibling = parent->rb_left;
+                       if (rb_is_red(sibling)) {
+                               /* Case 1 - right rotate at parent */
+                               parent->rb_left = tmp1 = sibling->rb_right;
+                               sibling->rb_right = parent;
+                               rb_set_parent_color(tmp1, parent, RB_BLACK);
+                               __rb_rotate_set_parents(parent, sibling, root,
+                                                       RB_RED);
+                               augment_rotate(parent, sibling);
+                               sibling = tmp1;
                        }
-                       else
-                       {
-                               if (!other->rb_left || rb_is_black(other->rb_left))
-                               {
-                                       register struct rb_node *o_right;
-                                       if ((o_right = other->rb_right))
-                                               rb_set_black(o_right);
-                                       rb_set_red(other);
-                                       __rb_rotate_left(other, root);
-                                       other = parent->rb_left;
+                       tmp1 = sibling->rb_left;
+                       if (!tmp1 || rb_is_black(tmp1)) {
+                               tmp2 = sibling->rb_right;
+                               if (!tmp2 || rb_is_black(tmp2)) {
+                                       /* Case 2 - sibling color flip */
+                                       rb_set_parent_color(sibling, parent,
+                                                           RB_RED);
+                                       if (rb_is_red(parent))
+                                               rb_set_black(parent);
+                                       else {
+                                               node = parent;
+                                               parent = rb_parent(node);
+                                               if (parent)
+                                                       continue;
+                                       }
+                                       break;
                                }
-                               rb_set_color(other, rb_color(parent));
-                               rb_set_black(parent);
-                               if (other->rb_left)
-                                       rb_set_black(other->rb_left);
-                               __rb_rotate_right(parent, root);
-                               node = root->rb_node;
-                               break;
+                               /* Case 3 - right rotate at sibling */
+                               sibling->rb_right = tmp1 = tmp2->rb_left;
+                               tmp2->rb_left = sibling;
+                               parent->rb_left = tmp2;
+                               if (tmp1)
+                                       rb_set_parent_color(tmp1, sibling,
+                                                           RB_BLACK);
+                               augment_rotate(sibling, tmp2);
+                               tmp1 = sibling;
+                               sibling = tmp2;
                        }
+                       /* Case 4 - left rotate at parent + color flips */
+                       parent->rb_left = tmp2 = sibling->rb_right;
+                       sibling->rb_right = parent;
+                       rb_set_parent_color(tmp1, sibling, RB_BLACK);
+                       if (tmp2)
+                               rb_set_parent(tmp2, parent);
+                       __rb_rotate_set_parents(parent, sibling, root,
+                                               RB_BLACK);
+                       augment_rotate(parent, sibling);
+                       break;
                }
        }
-       if (node)
-               rb_set_black(node);
+}
+
+/* Non-inline version for rb_erase_augmented() use */
+void __rb_erase_color(struct rb_node *parent, struct rb_root *root,
+       void (*augment_rotate)(struct rb_node *old, struct rb_node *new))
+{
+       ____rb_erase_color(parent, root, augment_rotate);
+}
+
+/*
+ * Non-augmented rbtree manipulation functions.
+ *
+ * We use dummy augmented callbacks here, and have the compiler optimize them
+ * out of the rb_insert_color() and rb_erase() function definitions.
+ */
+
+static inline void dummy_propagate(struct rb_node *node, struct rb_node *stop) {}
+static inline void dummy_copy(struct rb_node *old, struct rb_node *new) {}
+static inline void dummy_rotate(struct rb_node *old, struct rb_node *new) {}
+
+static const struct rb_augment_callbacks dummy_callbacks = {
+       dummy_propagate, dummy_copy, dummy_rotate
+};
+
+void rb_insert_color(struct rb_node *node, struct rb_root *root)
+{
+       __rb_insert(node, root, dummy_rotate);
 }
 
 void rb_erase(struct rb_node *node, struct rb_root *root)
 {
-       struct rb_node *child, *parent;
-       int color;
-
-       if (!node->rb_left)
-               child = node->rb_right;
-       else if (!node->rb_right)
-               child = node->rb_left;
-       else
-       {
-               struct rb_node *old = node, *left;
-
-               node = node->rb_right;
-               while ((left = node->rb_left) != NULL)
-                       node = left;
-               child = node->rb_right;
-               parent = rb_parent(node);
-               color = rb_color(node);
-
-               if (child)
-                       rb_set_parent(child, parent);
-               if (parent == old) {
-                       parent->rb_right = child;
-                       parent = node;
-               } else
-                       parent->rb_left = child;
-
-               node->rb_parent_color = old->rb_parent_color;
-               node->rb_right = old->rb_right;
-               node->rb_left = old->rb_left;
-
-               if (rb_parent(old))
-               {
-                       if (rb_parent(old)->rb_left == old)
-                               rb_parent(old)->rb_left = node;
-                       else
-                               rb_parent(old)->rb_right = node;
-               } else
-                       root->rb_node = node;
-
-               rb_set_parent(old->rb_left, node);
-               if (old->rb_right)
-                       rb_set_parent(old->rb_right, node);
-               goto color;
-       }
+       struct rb_node *rebalance;
+       rebalance = __rb_erase_augmented(node, root, &dummy_callbacks);
+       if (rebalance)
+               ____rb_erase_color(rebalance, root, dummy_rotate);
+}
 
-       parent = rb_parent(node);
-       color = rb_color(node);
-
-       if (child)
-               rb_set_parent(child, parent);
-       if (parent)
-       {
-               if (parent->rb_left == node)
-                       parent->rb_left = child;
-               else
-                       parent->rb_right = child;
-       }
-       else
-               root->rb_node = child;
+/*
+ * Augmented rbtree manipulation functions.
+ *
+ * This instantiates the same __always_inline functions as in the non-augmented
+ * case, but this time with user-defined callbacks.
+ */
 
- color:
-       if (color == RB_BLACK)
-               __rb_erase_color(child, parent, root);
+void __rb_insert_augmented(struct rb_node *node, struct rb_root *root,
+       void (*augment_rotate)(struct rb_node *old, struct rb_node *new))
+{
+       __rb_insert(node, root, augment_rotate);
 }
 
 /*
  * This function returns the first node (in sort order) of the tree.
  */
-struct rb_node *rb_first(struct rb_root *root)
+struct rb_node *rb_first(const struct rb_root *root)
 {
        struct rb_node  *n;
 
@@ -301,7 +422,7 @@ struct rb_node *rb_first(struct rb_root *root)
        return n;
 }
 
-struct rb_node *rb_last(struct rb_root *root)
+struct rb_node *rb_last(const struct rb_root *root)
 {
        struct rb_node  *n;
 
@@ -313,52 +434,59 @@ struct rb_node *rb_last(struct rb_root *root)
        return n;
 }
 
-struct rb_node *rb_next(struct rb_node *node)
+struct rb_node *rb_next(const struct rb_node *node)
 {
        struct rb_node *parent;
 
-       if (rb_parent(node) == node)
+       if (RB_EMPTY_NODE(node))
                return NULL;
 
-       /* If we have a right-hand child, go down and then left as far
-          as we can. */
+       /*
+        * If we have a right-hand child, go down and then left as far
+        * as we can.
+        */
        if (node->rb_right) {
                node = node->rb_right; 
                while (node->rb_left)
                        node=node->rb_left;
-               return node;
+               return (struct rb_node *)node;
        }
 
-       /* No right-hand children.  Everything down and left is
-          smaller than us, so any 'next' node must be in the general
-          direction of our parent. Go up the tree; any time the
-          ancestor is a right-hand child of its parent, keep going
-          up. First time it's a left-hand child of its parent, said
-          parent is our 'next' node. */
+       /*
+        * No right-hand children. Everything down and left is smaller than us,
+        * so any 'next' node must be in the general direction of our parent.
+        * Go up the tree; any time the ancestor is a right-hand child of its
+        * parent, keep going up. First time it's a left-hand child of its
+        * parent, said parent is our 'next' node.
+        */
        while ((parent = rb_parent(node)) && node == parent->rb_right)
                node = parent;
 
        return parent;
 }
 
-struct rb_node *rb_prev(struct rb_node *node)
+struct rb_node *rb_prev(const struct rb_node *node)
 {
        struct rb_node *parent;
 
-       if (rb_parent(node) == node)
+       if (RB_EMPTY_NODE(node))
                return NULL;
 
-       /* If we have a left-hand child, go down and then right as far
-          as we can. */
+       /*
+        * If we have a left-hand child, go down and then right as far
+        * as we can.
+        */
        if (node->rb_left) {
                node = node->rb_left; 
                while (node->rb_right)
                        node=node->rb_right;
-               return node;
+               return (struct rb_node *)node;
        }
 
-       /* No left-hand children. Go up till we find an ancestor which
-          is a right-hand child of its parent */
+       /*
+        * No left-hand children. Go up till we find an ancestor which
+        * is a right-hand child of its parent.
+        */
        while ((parent = rb_parent(node)) && node == parent->rb_left)
                node = parent;
 
@@ -371,14 +499,7 @@ void rb_replace_node(struct rb_node *victim, struct rb_node *new,
        struct rb_node *parent = rb_parent(victim);
 
        /* Set the surrounding nodes to point to the replacement */
-       if (parent) {
-               if (victim == parent->rb_left)
-                       parent->rb_left = new;
-               else
-                       parent->rb_right = new;
-       } else {
-               root->rb_node = new;
-       }
+       __rb_change_child(victim, new, parent, root);
        if (victim->rb_left)
                rb_set_parent(victim->rb_left, new);
        if (victim->rb_right)
@@ -387,3 +508,41 @@ void rb_replace_node(struct rb_node *victim, struct rb_node *new,
        /* Copy the pointers/colour from the victim to the replacement */
        *new = *victim;
 }
+
+static struct rb_node *rb_left_deepest_node(const struct rb_node *node)
+{
+       for (;;) {
+               if (node->rb_left)
+                       node = node->rb_left;
+               else if (node->rb_right)
+                       node = node->rb_right;
+               else
+                       return (struct rb_node *)node;
+       }
+}
+
+struct rb_node *rb_next_postorder(const struct rb_node *node)
+{
+       const struct rb_node *parent;
+       if (!node)
+               return NULL;
+       parent = rb_parent(node);
+
+       /* If we're sitting on node, we've already seen our children */
+       if (parent && node == parent->rb_left && parent->rb_right) {
+               /* If we are the parent's left node, go to the parent's right
+                * node then all the way down to the left */
+               return rb_left_deepest_node(parent->rb_right);
+       } else
+               /* Otherwise we are the parent's right node, and the parent
+                * should be next */
+               return (struct rb_node *)parent;
+}
+
+struct rb_node *rb_first_postorder(const struct rb_root *root)
+{
+       if (!root->rb_node)
+               return NULL;
+
+       return rb_left_deepest_node(root->rb_node);
+}
index 3add424..03c06d8 100644 (file)
--- a/rbtree.h
+++ b/rbtree.h
   I know it's not the cleaner way,  but in C (not in C++) to get
   performances and genericity...
 
-  Some example of insert and search follows here. The search is a plain
-  normal search over an ordered tree. The insert instead must be implemented
-  int two steps: as first thing the code must insert the element in
-  order as a red leaf in the tree, then the support library function
-  rb_insert_color() must be called. Such function will do the
-  not trivial work to rebalance the rbtree if necessary.
-
------------------------------------------------------------------------
-static inline struct page * rb_search_page_cache(struct inode * inode,
-                                                unsigned long offset)
-{
-       struct rb_node * n = inode->i_rb_page_cache.rb_node;
-       struct page * page;
-
-       while (n)
-       {
-               page = rb_entry(n, struct page, rb_page_cache);
-
-               if (offset < page->offset)
-                       n = n->rb_left;
-               else if (offset > page->offset)
-                       n = n->rb_right;
-               else
-                       return page;
-       }
-       return NULL;
-}
-
-static inline struct page * __rb_insert_page_cache(struct inode * inode,
-                                                  unsigned long offset,
-                                                  struct rb_node * node)
-{
-       struct rb_node ** p = &inode->i_rb_page_cache.rb_node;
-       struct rb_node * parent = NULL;
-       struct page * page;
-
-       while (*p)
-       {
-               parent = *p;
-               page = rb_entry(parent, struct page, rb_page_cache);
-
-               if (offset < page->offset)
-                       p = &(*p)->rb_left;
-               else if (offset > page->offset)
-                       p = &(*p)->rb_right;
-               else
-                       return page;
-       }
-
-       rb_link_node(node, parent, p);
-
-       return NULL;
-}
-
-static inline struct page * rb_insert_page_cache(struct inode * inode,
-                                                unsigned long offset,
-                                                struct rb_node * node)
-{
-       struct page * ret;
-       if ((ret = __rb_insert_page_cache(inode, offset, node)))
-               goto out;
-       rb_insert_color(node, &inode->i_rb_page_cache);
- out:
-       return ret;
-}
------------------------------------------------------------------------
+  See Documentation/rbtree.txt for documentation and samples.
 */
 
 #ifndef        _LINUX_RBTREE_H
@@ -98,63 +33,78 @@ static inline struct page * rb_insert_page_cache(struct inode * inode,
 #else
 #include <btrfs/kerncompat.h>
 #endif /* BTRFS_FLAT_INCLUDES */
-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)
 
-#define RB_EMPTY_ROOT(root)    ((root)->rb_node == NULL)
-#define RB_EMPTY_NODE(node)    (rb_parent(node) == node)
-#define RB_CLEAR_NODE(node)    (rb_set_parent(node, node))
+#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))
+
 
 extern void rb_insert_color(struct rb_node *, struct rb_root *);
 extern void rb_erase(struct rb_node *, struct rb_root *);
 
+
 /* Find logical next and previous nodes in a tree */
-extern struct rb_node *rb_next(struct rb_node *);
-extern struct rb_node *rb_prev(struct rb_node *);
-extern struct rb_node *rb_first(struct rb_root *);
-extern struct rb_node *rb_last(struct rb_root *);
+extern struct rb_node *rb_next(const struct rb_node *);
+extern struct rb_node *rb_prev(const struct rb_node *);
+extern struct rb_node *rb_first(const struct rb_root *);
+extern struct rb_node *rb_last(const struct rb_root *);
+
+/* Postorder iteration - always visit the parent after its children */
+extern struct rb_node *rb_first_postorder(const struct rb_root *);
+extern struct rb_node *rb_next_postorder(const struct rb_node *);
 
 /* Fast replacement of a single node without remove/rebalance/add/rebalance */
-extern void rb_replace_node(struct rb_node *victim, struct rb_node *xnew,
+extern void rb_replace_node(struct rb_node *victim, struct rb_node *new, 
                            struct rb_root *root);
 
 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;
 }
+
+#define rb_entry_safe(ptr, type, member) \
+       ({ typeof(ptr) ____ptr = (ptr); \
+          ____ptr ? rb_entry(____ptr, type, member) : NULL; \
+       })
+
+/**
+ * rbtree_postorder_for_each_entry_safe - iterate over rb_root in post order of
+ * given type safe against removal of rb_node entry
+ *
+ * @pos:       the 'type *' to use as a loop cursor.
+ * @n:         another 'type *' to use as temporary storage
+ * @root:      'rb_root *' of the rbtree.
+ * @field:     the name of the rb_node field within 'type'.
+ */
+#define rbtree_postorder_for_each_entry_safe(pos, n, root, field) \
+       for (pos = rb_entry_safe(rb_first_postorder(root), typeof(*pos), field); \
+            pos && ({ n = rb_entry_safe(rb_next_postorder(&pos->field), \
+                       typeof(*pos), field); 1; }); \
+            pos = n)
+
 #endif /* _LINUX_RBTREE_H */
diff --git a/rbtree_augmented.h b/rbtree_augmented.h
new file mode 100644 (file)
index 0000000..079eb97
--- /dev/null
@@ -0,0 +1,231 @@
+/*
+  Red Black Trees
+  (C) 1999  Andrea Arcangeli <andrea@suse.de>
+  (C) 2002  David Woodhouse <dwmw2@infradead.org>
+  (C) 2012  Michel Lespinasse <walken@google.com>
+
+  This program is free software; you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation; either version 2 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program; if not, write to the Free Software
+  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+
+  linux/include/linux/rbtree_augmented.h
+*/
+
+#ifndef _LINUX_RBTREE_AUGMENTED_H
+#define _LINUX_RBTREE_AUGMENTED_H
+
+#include "rbtree.h"
+
+/*
+ * Please note - only struct rb_augment_callbacks and the prototypes for
+ * rb_insert_augmented() and rb_erase_augmented() are intended to be public.
+ * The rest are implementation details you are not expected to depend on.
+ *
+ * See Documentation/rbtree.txt for documentation and samples.
+ */
+
+struct rb_augment_callbacks {
+       void (*propagate)(struct rb_node *node, struct rb_node *stop);
+       void (*copy)(struct rb_node *old, struct rb_node *new);
+       void (*rotate)(struct rb_node *old, struct rb_node *new);
+};
+
+extern void __rb_insert_augmented(struct rb_node *node, struct rb_root *root,
+       void (*augment_rotate)(struct rb_node *old, struct rb_node *new));
+static inline void
+rb_insert_augmented(struct rb_node *node, struct rb_root *root,
+                   const struct rb_augment_callbacks *augment)
+{
+       __rb_insert_augmented(node, root, augment->rotate);
+}
+
+#define RB_DECLARE_CALLBACKS(rbstatic, rbname, rbstruct, rbfield,      \
+                            rbtype, rbaugmented, rbcompute)            \
+static inline void                                                     \
+rbname ## _propagate(struct rb_node *rb, struct rb_node *stop)         \
+{                                                                      \
+       while (rb != stop) {                                            \
+               rbstruct *node = rb_entry(rb, rbstruct, rbfield);       \
+               rbtype augmented = rbcompute(node);                     \
+               if (node->rbaugmented == augmented)                     \
+                       break;                                          \
+               node->rbaugmented = augmented;                          \
+               rb = rb_parent(&node->rbfield);                         \
+       }                                                               \
+}                                                                      \
+static inline void                                                     \
+rbname ## _copy(struct rb_node *rb_old, struct rb_node *rb_new)                \
+{                                                                      \
+       rbstruct *old = rb_entry(rb_old, rbstruct, rbfield);            \
+       rbstruct *new = rb_entry(rb_new, rbstruct, rbfield);            \
+       new->rbaugmented = old->rbaugmented;                            \
+}                                                                      \
+static void                                                            \
+rbname ## _rotate(struct rb_node *rb_old, struct rb_node *rb_new)      \
+{                                                                      \
+       rbstruct *old = rb_entry(rb_old, rbstruct, rbfield);            \
+       rbstruct *new = rb_entry(rb_new, rbstruct, rbfield);            \
+       new->rbaugmented = old->rbaugmented;                            \
+       old->rbaugmented = rbcompute(old);                              \
+}                                                                      \
+rbstatic const struct rb_augment_callbacks rbname = {                  \
+       rbname ## _propagate, rbname ## _copy, rbname ## _rotate        \
+};
+
+
+#define        RB_RED          0
+#define        RB_BLACK        1
+
+#define __rb_parent(pc)    ((struct rb_node *)(pc & ~3))
+
+#define __rb_color(pc)     ((pc) & 1)
+#define __rb_is_black(pc)  __rb_color(pc)
+#define __rb_is_red(pc)    (!__rb_color(pc))
+#define rb_color(rb)       __rb_color((rb)->__rb_parent_color)
+#define rb_is_red(rb)      __rb_is_red((rb)->__rb_parent_color)
+#define rb_is_black(rb)    __rb_is_black((rb)->__rb_parent_color)
+
+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_parent_color(struct rb_node *rb,
+                                      struct rb_node *p, int color)
+{
+       rb->__rb_parent_color = (unsigned long)p | color;
+}
+
+static inline void
+__rb_change_child(struct rb_node *old, struct rb_node *new,
+                 struct rb_node *parent, struct rb_root *root)
+{
+       if (parent) {
+               if (parent->rb_left == old)
+                       parent->rb_left = new;
+               else
+                       parent->rb_right = new;
+       } else
+               root->rb_node = new;
+}
+
+extern void __rb_erase_color(struct rb_node *parent, struct rb_root *root,
+       void (*augment_rotate)(struct rb_node *old, struct rb_node *new));
+
+static __always_inline struct rb_node *
+__rb_erase_augmented(struct rb_node *node, struct rb_root *root,
+                    const struct rb_augment_callbacks *augment)
+{
+       struct rb_node *child = node->rb_right, *tmp = node->rb_left;
+       struct rb_node *parent, *rebalance;
+       unsigned long pc;
+
+       if (!tmp) {
+               /*
+                * Case 1: node to erase has no more than 1 child (easy!)
+                *
+                * Note that if there is one child it must be red due to 5)
+                * and node must be black due to 4). We adjust colors locally
+                * so as to bypass __rb_erase_color() later on.
+                */
+               pc = node->__rb_parent_color;
+               parent = __rb_parent(pc);
+               __rb_change_child(node, child, parent, root);
+               if (child) {
+                       child->__rb_parent_color = pc;
+                       rebalance = NULL;
+               } else
+                       rebalance = __rb_is_black(pc) ? parent : NULL;
+               tmp = parent;
+       } else if (!child) {
+               /* Still case 1, but this time the child is node->rb_left */
+               tmp->__rb_parent_color = pc = node->__rb_parent_color;
+               parent = __rb_parent(pc);
+               __rb_change_child(node, tmp, parent, root);
+               rebalance = NULL;
+               tmp = parent;
+       } else {
+               struct rb_node *successor = child, *child2;
+               tmp = child->rb_left;
+               if (!tmp) {
+                       /*
+                        * Case 2: node's successor is its right child
+                        *
+                        *    (n)          (s)
+                        *    / \          / \
+                        *  (x) (s)  ->  (x) (c)
+                        *        \
+                        *        (c)
+                        */
+                       parent = successor;
+                       child2 = successor->rb_right;
+                       augment->copy(node, successor);
+               } else {
+                       /*
+                        * Case 3: node's successor is leftmost under
+                        * node's right child subtree
+                        *
+                        *    (n)          (s)
+                        *    / \          / \
+                        *  (x) (y)  ->  (x) (y)
+                        *      /            /
+                        *    (p)          (p)
+                        *    /            /
+                        *  (s)          (c)
+                        *    \
+                        *    (c)
+                        */
+                       do {
+                               parent = successor;
+                               successor = tmp;
+                               tmp = tmp->rb_left;
+                       } while (tmp);
+                       parent->rb_left = child2 = successor->rb_right;
+                       successor->rb_right = child;
+                       rb_set_parent(child, successor);
+                       augment->copy(node, successor);
+                       augment->propagate(parent, successor);
+               }
+
+               successor->rb_left = tmp = node->rb_left;
+               rb_set_parent(tmp, successor);
+
+               pc = node->__rb_parent_color;
+               tmp = __rb_parent(pc);
+               __rb_change_child(node, successor, tmp, root);
+               if (child2) {
+                       successor->__rb_parent_color = pc;
+                       rb_set_parent_color(child2, parent, RB_BLACK);
+                       rebalance = NULL;
+               } else {
+                       unsigned long pc2 = successor->__rb_parent_color;
+                       successor->__rb_parent_color = pc;
+                       rebalance = __rb_is_black(pc2) ? parent : NULL;
+               }
+               tmp = successor;
+       }
+
+       augment->propagate(tmp, NULL);
+       return rebalance;
+}
+
+static __always_inline void
+rb_erase_augmented(struct rb_node *node, struct rb_root *root,
+                  const struct rb_augment_callbacks *augment)
+{
+       struct rb_node *rebalance = __rb_erase_augmented(node, root, augment);
+       if (rebalance)
+               __rb_erase_color(rebalance, root, augment->rotate);
+}
+
+#endif /* _LINUX_RBTREE_AUGMENTED_H */