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xarray: Step through an XArray

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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 <willy@infradead.org>
This commit is contained in:
Matthew Wilcox
2017-12-01 00:06:52 -05:00
parent 687149fca1
commit 64d3e9a9e0
3 changed files with 256 additions and 0 deletions
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115
lib/test_xarray.c
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@@ -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;