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-rw-r--r--lib/interval_tree.c132
1 files changed, 132 insertions, 0 deletions
diff --git a/lib/interval_tree.c b/lib/interval_tree.c
index 593ce56ece50..3412737ff365 100644
--- a/lib/interval_tree.c
+++ b/lib/interval_tree.c
@@ -15,3 +15,135 @@ EXPORT_SYMBOL_GPL(interval_tree_insert);
EXPORT_SYMBOL_GPL(interval_tree_remove);
EXPORT_SYMBOL_GPL(interval_tree_iter_first);
EXPORT_SYMBOL_GPL(interval_tree_iter_next);
+
+#ifdef CONFIG_INTERVAL_TREE_SPAN_ITER
+/*
+ * Roll nodes[1] into nodes[0] by advancing nodes[1] to the end of a contiguous
+ * span of nodes. This makes nodes[0]->last the end of that contiguous used span
+ * indexes that started at the original nodes[1]->start. nodes[1] is now the
+ * first node starting the next used span. A hole span is between nodes[0]->last
+ * and nodes[1]->start. nodes[1] must be !NULL.
+ */
+static void
+interval_tree_span_iter_next_gap(struct interval_tree_span_iter *state)
+{
+ struct interval_tree_node *cur = state->nodes[1];
+
+ state->nodes[0] = cur;
+ do {
+ if (cur->last > state->nodes[0]->last)
+ state->nodes[0] = cur;
+ cur = interval_tree_iter_next(cur, state->first_index,
+ state->last_index);
+ } while (cur && (state->nodes[0]->last >= cur->start ||
+ state->nodes[0]->last + 1 == cur->start));
+ state->nodes[1] = cur;
+}
+
+void interval_tree_span_iter_first(struct interval_tree_span_iter *iter,
+ struct rb_root_cached *itree,
+ unsigned long first_index,
+ unsigned long last_index)
+{
+ iter->first_index = first_index;
+ iter->last_index = last_index;
+ iter->nodes[0] = NULL;
+ iter->nodes[1] =
+ interval_tree_iter_first(itree, first_index, last_index);
+ if (!iter->nodes[1]) {
+ /* No nodes intersect the span, whole span is hole */
+ iter->start_hole = first_index;
+ iter->last_hole = last_index;
+ iter->is_hole = 1;
+ return;
+ }
+ if (iter->nodes[1]->start > first_index) {
+ /* Leading hole on first iteration */
+ iter->start_hole = first_index;
+ iter->last_hole = iter->nodes[1]->start - 1;
+ iter->is_hole = 1;
+ interval_tree_span_iter_next_gap(iter);
+ return;
+ }
+
+ /* Starting inside a used */
+ iter->start_used = first_index;
+ iter->is_hole = 0;
+ interval_tree_span_iter_next_gap(iter);
+ iter->last_used = iter->nodes[0]->last;
+ if (iter->last_used >= last_index) {
+ iter->last_used = last_index;
+ iter->nodes[0] = NULL;
+ iter->nodes[1] = NULL;
+ }
+}
+EXPORT_SYMBOL_GPL(interval_tree_span_iter_first);
+
+void interval_tree_span_iter_next(struct interval_tree_span_iter *iter)
+{
+ if (!iter->nodes[0] && !iter->nodes[1]) {
+ iter->is_hole = -1;
+ return;
+ }
+
+ if (iter->is_hole) {
+ iter->start_used = iter->last_hole + 1;
+ iter->last_used = iter->nodes[0]->last;
+ if (iter->last_used >= iter->last_index) {
+ iter->last_used = iter->last_index;
+ iter->nodes[0] = NULL;
+ iter->nodes[1] = NULL;
+ }
+ iter->is_hole = 0;
+ return;
+ }
+
+ if (!iter->nodes[1]) {
+ /* Trailing hole */
+ iter->start_hole = iter->nodes[0]->last + 1;
+ iter->last_hole = iter->last_index;
+ iter->nodes[0] = NULL;
+ iter->is_hole = 1;
+ return;
+ }
+
+ /* must have both nodes[0] and [1], interior hole */
+ iter->start_hole = iter->nodes[0]->last + 1;
+ iter->last_hole = iter->nodes[1]->start - 1;
+ iter->is_hole = 1;
+ interval_tree_span_iter_next_gap(iter);
+}
+EXPORT_SYMBOL_GPL(interval_tree_span_iter_next);
+
+/*
+ * Advance the iterator index to a specific position. The returned used/hole is
+ * updated to start at new_index. This is faster than calling
+ * interval_tree_span_iter_first() as it can avoid full searches in several
+ * cases where the iterator is already set.
+ */
+void interval_tree_span_iter_advance(struct interval_tree_span_iter *iter,
+ struct rb_root_cached *itree,
+ unsigned long new_index)
+{
+ if (iter->is_hole == -1)
+ return;
+
+ iter->first_index = new_index;
+ if (new_index > iter->last_index) {
+ iter->is_hole = -1;
+ return;
+ }
+
+ /* Rely on the union aliasing hole/used */
+ if (iter->start_hole <= new_index && new_index <= iter->last_hole) {
+ iter->start_hole = new_index;
+ return;
+ }
+ if (new_index == iter->last_hole + 1)
+ interval_tree_span_iter_next(iter);
+ else
+ interval_tree_span_iter_first(iter, itree, new_index,
+ iter->last_index);
+}
+EXPORT_SYMBOL_GPL(interval_tree_span_iter_advance);
+#endif