}
}
-int for_dentry_tree_in_rbtree(struct rb_node *root,
- int (*visitor)(struct dentry*, void*),
- void *arg)
-{
- int ret;
- struct rb_node *node = root;
- LIST_HEAD(stack);
- while (true) {
- if (node) {
- list_add(&rbnode_dentry(node)->tmp_list, &stack);
- node = node->rb_left;
- } else {
- struct list_head *next;
- struct dentry *dentry;
-
- next = stack.next;
- if (next == &stack)
- return 0;
- dentry = container_of(next, struct dentry, tmp_list);
- list_del(next);
- ret = for_dentry_in_tree(dentry, visitor, arg);
- if (ret != 0)
- return ret;
- node = dentry->rb_node.rb_right;
- }
- }
-}
-
static int for_dentry_tree_in_rbtree_depth(struct rb_node *node,
int (*visitor)(struct dentry*, void*),
void *arg)
}
/*
- * Calls a function on all directory entries in a directory tree. It is called
- * on a parent before its children.
+ * Calls a function on all directory entries in a WIM dentry tree. Logically,
+ * this is a pre-order traversal (the function is called on a parent dentry
+ * before its children), but sibling dentries will be visited in order as well.
+ *
+ * In reality, the data structures are more complicated than the above might
+ * suggest because there is a separate red-black tree for each dentry that
+ * contains its direct children.
*/
int for_dentry_in_tree(struct dentry *root,
int (*visitor)(struct dentry*, void*), void *arg)
{
- int ret = visitor(root, arg);
+ int ret;
+ struct list_head main_stack;
+ struct list_head sibling_stack;
+ struct list_head *sibling_stack_bottom;
+ struct dentry *main_dentry;
+ struct rb_node *node;
+ struct list_head *next_sibling;
+ struct dentry *dentry;
+
+ ret = visitor(root, arg);
if (ret != 0)
return ret;
- return for_dentry_tree_in_rbtree(root->d_inode->children.rb_node,
- visitor, arg);
+ main_dentry = root;
+ sibling_stack_bottom = &sibling_stack;
+ INIT_LIST_HEAD(&main_stack);
+ INIT_LIST_HEAD(&sibling_stack);
+
+ list_add(&main_dentry->tmp_list, &main_stack);
+
+ while (1) {
+ // Prepare for non-recursive in-order traversal of the red-black
+ // tree of this dentry's children
+ node = main_dentry->d_inode->children.rb_node;
+
+ while (node) {
+ // Push this node to the sibling stack and examine the
+ // left neighbor, if any
+ list_add(&rbnode_dentry(node)->tmp_list, &sibling_stack);
+ push_left_siblings:
+ node = node->rb_left;
+ }
+
+
+ pop_sibling:
+
+ next_sibling = sibling_stack.next;
+ if (next_sibling == sibling_stack_bottom) {
+ // Done with all siblings. Pop the main dentry to move
+ // back up one level.
+ main_dentry = container_of(main_stack.next,
+ struct dentry,
+ tmp_list);
+ list_del(&main_dentry->tmp_list);
+
+ if (main_dentry == root) {
+ ret = 0;
+ goto out;
+ }
+
+ // Restore sibling stack bottom from the previous level
+ sibling_stack_bottom = (void*)main_dentry->parent;
+
+ // Restore the just-popped main dentry's parent
+ main_dentry->parent = container_of(main_stack.next,
+ struct dentry,
+ tmp_list);
+
+ // The next sibling to traverse in the previous level,
+ // in the in-order traversal of the red-black tree, is
+ // the one to the right.
+ node = main_dentry->rb_node.rb_right;
+ if (node) {
+ list_add(&rbnode_dentry(node)->tmp_list,
+ &sibling_stack);
+ goto push_left_siblings;
+ } else {
+ goto pop_sibling;
+ }
+ } else {
+ // The sibling stack is not empty, so there are more to
+ // go!
+
+ // Pop a sibling from the stack.
+ list_del(next_sibling);
+ dentry = container_of(next_sibling, struct dentry, tmp_list);
+
+ // Visit the sibling.
+ ret = visitor(dentry, arg);
+ if (ret != 0) {
+ // Failed. Restore parent pointers for the
+ // dentries in the main stack
+ list_del(&root->tmp_list);
+ list_for_each_entry(dentry, &main_stack, tmp_list) {
+ dentry->parent = container_of(dentry->tmp_list.next,
+ struct dentry,
+ tmp_list);
+ }
+ goto out;
+ }
+
+ // We'd like to recursively visit the dentry tree rooted
+ // at this sibling. To do this, add it to the main
+ // stack, save the bottom of this level's sibling stack
+ // in the dentry->parent field, re-set the bottom of the
+ // sibling stack to be its current height, and set
+ // main_dentry to the sibling so it becomes the parent
+ // dentry in the next iteration through the outer loop.
+ list_add(&dentry->tmp_list, &main_stack);
+ dentry->parent = (void*)sibling_stack_bottom;
+ sibling_stack_bottom = sibling_stack.next;
+
+ main_dentry = dentry;
+ }
+ }
+out:
+ root->parent = root;
+ return ret;
}
/*
int for_dentry_in_tree_depth(struct dentry *root,
int (*visitor)(struct dentry*, void*), void *arg)
{
-
- int ret = for_dentry_tree_in_rbtree_depth(root->d_inode->children.rb_node,
- visitor, arg);
+#if 1
+ int ret;
+ ret = for_dentry_tree_in_rbtree_depth(root->d_inode->children.rb_node,
+ visitor, arg);
if (ret != 0)
return ret;
return visitor(root, arg);
+
+#else
+ int ret;
+ struct list_head main_stack;
+ struct list_head sibling_stack;
+ struct list_head *sibling_stack_bottom;
+ struct dentry *main_dentry;
+ struct rb_node *node;
+ struct list_head *next_sibling;
+ struct dentry *dentry;
+
+ main_dentry = root;
+ sibling_stack_bottom = &sibling_stack;
+ INIT_LIST_HEAD(&main_stack);
+ INIT_LIST_HEAD(&sibling_stack);
+
+ list_add(&main_dentry->tmp_list, &main_stack);
+
+ while (1) {
+ node = main_dentry->d_inode->children.rb_node;
+
+ while (1) {
+ if (node->rb_left) {
+ list_add(&rbnode_dentry(node)->tmp_list, &sibling_stack);
+ node = node->rb_left;
+ continue;
+ }
+ if (node->rb_right) {
+ list_add(&rbnode_dentry(node)->tmp_list, &sibling_stack);
+ node = node->rb_right;
+ continue;
+ }
+ list_add(&rbnode_dentry(node)->tmp_list, &sibling_stack);
+ }
+
+ pop_sibling:
+ next_sibling = sibling_stack.next;
+ if (next_sibling == sibling_stack_bottom) {
+ main_dentry = container_of(main_stack.next,
+ struct dentry,
+ tmp_list);
+ list_del(&main_dentry->tmp_list);
+
+
+ sibling_stack_bottom = (void*)main_dentry->parent;
+
+ if (main_dentry == root) {
+ main_dentry->parent = main_dentry;
+ ret = visitor(dentry, arg);
+ return ret;
+ } else {
+ main_dentry->parent = container_of(main_stack.next,
+ struct dentry,
+ tmp_list);
+ }
+
+ ret = visitor(main_dentry, arg);
+
+ if (ret != 0) {
+ list_del(&root->tmp_list);
+ list_for_each_entry(dentry, &main_stack, tmp_list) {
+ dentry->parent = container_of(dentry->tmp_list.next,
+ struct dentry,
+ tmp_list);
+ }
+ root->parent = root;
+ return ret;
+ }
+ goto pop_sibling;
+ } else {
+
+ list_del(next_sibling);
+ dentry = container_of(next_sibling, struct dentry, tmp_list);
+
+
+ list_add(&dentry->tmp_list, &main_stack);
+ dentry->parent = (void*)sibling_stack_bottom;
+ sibling_stack_bottom = sibling_stack.next;
+
+ main_dentry = dentry;
+ }
+ }
+#endif
}
/*