@@ -99,6 +99,25 @@ static inline void inc_frontswap_invalidates(void) { }
*/
void frontswap_register_ops(struct frontswap_ops *ops)
{
+ DECLARE_BITMAP(a, MAX_SWAPFILES);
+ DECLARE_BITMAP(b, MAX_SWAPFILES);
+ struct swap_info_struct *si;
+ unsigned int i;
+
+ bitmap_zero(a, MAX_SWAPFILES);
+ bitmap_zero(b, MAX_SWAPFILES);
+
+ spin_lock(&swap_lock);
+ plist_for_each_entry(si, &swap_active_head, list) {
+ if (!WARN_ON(!si->frontswap_map))
+ __set_bit(si->type, a);
+ }
+ spin_unlock(&swap_lock);
+
+ /* the new ops needs to know the currently active swap devices */
+ for_each_set_bit(i, a, MAX_SWAPFILES)
+ ops->init(i);
+
/*
* Setting frontswap_ops must happen after the ops->init() calls
* above; cmpxchg implies smp_mb() which will ensure the init is
@@ -109,6 +128,28 @@ void frontswap_register_ops(struct frontswap_ops *ops)
} while (cmpxchg(&frontswap_ops, ops->next, ops) != ops->next);
static_branch_inc(&frontswap_enabled_key);
+
+ spin_lock(&swap_lock);
+ plist_for_each_entry(si, &swap_active_head, list) {
+ if (si->frontswap_map)
+ __set_bit(si->type, b);
+ }
+ spin_unlock(&swap_lock);
+
+ /*
+ * On the very unlikely chance that a swap device was added or
+ * removed between setting the "a" list bits and the ops init
+ * calls, we re-check and do init or invalidate for any changed
+ * bits.
+ */
+ if (unlikely(!bitmap_equal(a, b, MAX_SWAPFILES))) {
+ for (i = 0; i < MAX_SWAPFILES; i++) {
+ if (!test_bit(i, a) && test_bit(i, b))
+ ops->init(i);
+ else if (test_bit(i, a) && !test_bit(i, b))
+ ops->invalidate_area(i);
+ }
+ }
}
/*
This reverts commit f328c1d16e4c764992895ac9c9425cea861b2ca0. Since we are supported to delay zswap initializaton, we need to invoke ops->init for the swap device which is already online when register backend. Signed-off-by: Liu Shixin <liushixin2@huawei.com> --- mm/frontswap.c | 41 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 41 insertions(+)