XArray: Add private interface for workingset node deletion
Move the tricky bits of dealing with the XArray from the workingset
code to the XArray. Make it clear in the documentation that this is a
private interface, and only export it for the benefit of the test suite.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
diff --git a/lib/xarray.c b/lib/xarray.c
index e9e641d..1fa5c56 100644
--- a/lib/xarray.c
+++ b/lib/xarray.c
@@ -1974,6 +1974,29 @@
EXPORT_SYMBOL(xa_extract);
/**
+ * xa_delete_node() - Private interface for workingset code.
+ * @node: Node to be removed from the tree.
+ * @update: Function to call to update ancestor nodes.
+ *
+ * Context: xa_lock must be held on entry and will not be released.
+ */
+void xa_delete_node(struct xa_node *node, xa_update_node_t update)
+{
+ struct xa_state xas = {
+ .xa = node->array,
+ .xa_index = (unsigned long)node->offset <<
+ (node->shift + XA_CHUNK_SHIFT),
+ .xa_shift = node->shift + XA_CHUNK_SHIFT,
+ .xa_offset = node->offset,
+ .xa_node = xa_parent_locked(node->array, node),
+ .xa_update = update,
+ };
+
+ xas_store(&xas, NULL);
+}
+EXPORT_SYMBOL_GPL(xa_delete_node); /* For the benefit of the test suite */
+
+/**
* xa_destroy() - Free all internal data structures.
* @xa: XArray.
*