xarray: Step through an XArray
The xas_next and xas_prev functions move the xas index by one position,
and adjust the rest of the iterator state to match it. This is more
efficient than calling xas_set() as it keeps the iterator at the leaves
of the tree instead of walking the iterator from the root each time.
Signed-off-by: Matthew Wilcox <[email protected]>
diff --git a/lib/test_xarray.c b/lib/test_xarray.c
index a96f67ca..85ef188 100644
--- a/lib/test_xarray.c
+++ b/lib/test_xarray.c
@@ -465,6 +465,120 @@ static noinline void check_find(struct xarray *xa)
check_multi_find_2(xa);
}
+static noinline void check_move_small(struct xarray *xa, unsigned long idx)
+{
+ XA_STATE(xas, xa, 0);
+ unsigned long i;
+
+ xa_store_index(xa, 0, GFP_KERNEL);
+ xa_store_index(xa, idx, GFP_KERNEL);
+
+ rcu_read_lock();
+ for (i = 0; i < idx * 4; i++) {
+ void *entry = xas_next(&xas);
+ if (i <= idx)
+ XA_BUG_ON(xa, xas.xa_node == XAS_RESTART);
+ XA_BUG_ON(xa, xas.xa_index != i);
+ if (i == 0 || i == idx)
+ XA_BUG_ON(xa, entry != xa_mk_value(i));
+ else
+ XA_BUG_ON(xa, entry != NULL);
+ }
+ xas_next(&xas);
+ XA_BUG_ON(xa, xas.xa_index != i);
+
+ do {
+ void *entry = xas_prev(&xas);
+ i--;
+ if (i <= idx)
+ XA_BUG_ON(xa, xas.xa_node == XAS_RESTART);
+ XA_BUG_ON(xa, xas.xa_index != i);
+ if (i == 0 || i == idx)
+ XA_BUG_ON(xa, entry != xa_mk_value(i));
+ else
+ XA_BUG_ON(xa, entry != NULL);
+ } while (i > 0);
+
+ xas_set(&xas, ULONG_MAX);
+ XA_BUG_ON(xa, xas_next(&xas) != NULL);
+ XA_BUG_ON(xa, xas.xa_index != ULONG_MAX);
+ XA_BUG_ON(xa, xas_next(&xas) != xa_mk_value(0));
+ XA_BUG_ON(xa, xas.xa_index != 0);
+ XA_BUG_ON(xa, xas_prev(&xas) != NULL);
+ XA_BUG_ON(xa, xas.xa_index != ULONG_MAX);
+ rcu_read_unlock();
+
+ xa_erase_index(xa, 0);
+ xa_erase_index(xa, idx);
+ XA_BUG_ON(xa, !xa_empty(xa));
+}
+
+static noinline void check_move(struct xarray *xa)
+{
+ XA_STATE(xas, xa, (1 << 16) - 1);
+ unsigned long i;
+
+ for (i = 0; i < (1 << 16); i++)
+ XA_BUG_ON(xa, xa_store_index(xa, i, GFP_KERNEL) != NULL);
+
+ rcu_read_lock();
+ do {
+ void *entry = xas_prev(&xas);
+ i--;
+ XA_BUG_ON(xa, entry != xa_mk_value(i));
+ XA_BUG_ON(xa, i != xas.xa_index);
+ } while (i != 0);
+
+ XA_BUG_ON(xa, xas_prev(&xas) != NULL);
+ XA_BUG_ON(xa, xas.xa_index != ULONG_MAX);
+
+ do {
+ void *entry = xas_next(&xas);
+ XA_BUG_ON(xa, entry != xa_mk_value(i));
+ XA_BUG_ON(xa, i != xas.xa_index);
+ i++;
+ } while (i < (1 << 16));
+ rcu_read_unlock();
+
+ for (i = (1 << 8); i < (1 << 15); i++)
+ xa_erase_index(xa, i);
+
+ i = xas.xa_index;
+
+ rcu_read_lock();
+ do {
+ void *entry = xas_prev(&xas);
+ i--;
+ if ((i < (1 << 8)) || (i >= (1 << 15)))
+ XA_BUG_ON(xa, entry != xa_mk_value(i));
+ else
+ XA_BUG_ON(xa, entry != NULL);
+ XA_BUG_ON(xa, i != xas.xa_index);
+ } while (i != 0);
+
+ XA_BUG_ON(xa, xas_prev(&xas) != NULL);
+ XA_BUG_ON(xa, xas.xa_index != ULONG_MAX);
+
+ do {
+ void *entry = xas_next(&xas);
+ if ((i < (1 << 8)) || (i >= (1 << 15)))
+ XA_BUG_ON(xa, entry != xa_mk_value(i));
+ else
+ XA_BUG_ON(xa, entry != NULL);
+ XA_BUG_ON(xa, i != xas.xa_index);
+ i++;
+ } while (i < (1 << 16));
+ rcu_read_unlock();
+
+ xa_destroy(xa);
+
+ for (i = 0; i < 16; i++)
+ check_move_small(xa, 1UL << i);
+
+ for (i = 2; i < 16; i++)
+ check_move_small(xa, (1UL << i) - 1);
+}
+
static noinline void check_destroy(struct xarray *xa)
{
unsigned long index;
@@ -512,6 +626,7 @@ static int xarray_checks(void)
check_multi_store(&array);
check_find(&array);
check_destroy(&array);
+ check_move(&array);
printk("XArray: %u of %u tests passed\n", tests_passed, tests_run);
return (tests_run == tests_passed) ? 0 : -EINVAL;
