xarray: Add XArray load operation
The xa_load function brings with it a lot of infrastructure; xa_empty(),
xa_is_err(), and large chunks of the XArray advanced API that are used
to implement xa_load.
As the test-suite demonstrates, it is possible to use the XArray functions
on a radix tree. The radix tree functions depend on the GFP flags being
stored in the root of the tree, so it's not possible to use the radix
tree functions on an XArray.
Signed-off-by: Matthew Wilcox <willy@infradead.org>
diff --git a/lib/test_xarray.c b/lib/test_xarray.c
new file mode 100644
index 0000000..a7248b8
--- /dev/null
+++ b/lib/test_xarray.c
@@ -0,0 +1,87 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * test_xarray.c: Test the XArray API
+ * Copyright (c) 2017-2018 Microsoft Corporation
+ * Author: Matthew Wilcox <willy@infradead.org>
+ */
+
+#include <linux/xarray.h>
+#include <linux/module.h>
+
+static unsigned int tests_run;
+static unsigned int tests_passed;
+
+#ifndef XA_DEBUG
+# ifdef __KERNEL__
+void xa_dump(const struct xarray *xa) { }
+# endif
+#undef XA_BUG_ON
+#define XA_BUG_ON(xa, x) do { \
+ tests_run++; \
+ if (x) { \
+ printk("BUG at %s:%d\n", __func__, __LINE__); \
+ xa_dump(xa); \
+ dump_stack(); \
+ } else { \
+ tests_passed++; \
+ } \
+} while (0)
+#endif
+
+static void *xa_store_index(struct xarray *xa, unsigned long index, gfp_t gfp)
+{
+ radix_tree_insert(xa, index, xa_mk_value(index));
+ return NULL;
+}
+
+static void xa_erase_index(struct xarray *xa, unsigned long index)
+{
+ radix_tree_delete(xa, index);
+}
+
+static noinline void check_xa_load(struct xarray *xa)
+{
+ unsigned long i, j;
+
+ for (i = 0; i < 1024; i++) {
+ for (j = 0; j < 1024; j++) {
+ void *entry = xa_load(xa, j);
+ if (j < i)
+ XA_BUG_ON(xa, xa_to_value(entry) != j);
+ else
+ XA_BUG_ON(xa, entry);
+ }
+ XA_BUG_ON(xa, xa_store_index(xa, i, GFP_KERNEL) != NULL);
+ }
+
+ for (i = 0; i < 1024; i++) {
+ for (j = 0; j < 1024; j++) {
+ void *entry = xa_load(xa, j);
+ if (j >= i)
+ XA_BUG_ON(xa, xa_to_value(entry) != j);
+ else
+ XA_BUG_ON(xa, entry);
+ }
+ xa_erase_index(xa, i);
+ }
+ XA_BUG_ON(xa, !xa_empty(xa));
+}
+
+static RADIX_TREE(array, GFP_KERNEL);
+
+static int xarray_checks(void)
+{
+ check_xa_load(&array);
+
+ printk("XArray: %u of %u tests passed\n", tests_passed, tests_run);
+ return (tests_run == tests_passed) ? 0 : -EINVAL;
+}
+
+static void xarray_exit(void)
+{
+}
+
+module_init(xarray_checks);
+module_exit(xarray_exit);
+MODULE_AUTHOR("Matthew Wilcox <willy@infradead.org>");
+MODULE_LICENSE("GPL");