[PATCH v2 3/4] mm: zswap: avoid unnecessary xarray lookup in zswap_store()

[Kefeng Wang <wangkefeng.wang@huawei.com>]

zswap_store() falls through to check_old and walks the swap xarray
even when zswap is disabled. Add a zswap_never_enabled() early return
matching zswap_load() to avoid unnecessary xarray lookup.

Reviewed-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
 mm/zswap.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/mm/zswap.c b/mm/zswap.c
index 2c06e4e0e130..6197aa71e33c 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -1492,6 +1492,9 @@ bool zswap_store(struct folio *folio)
 	VM_WARN_ON_ONCE(!folio_test_locked(folio));
 	VM_WARN_ON_ONCE(!folio_test_swapcache(folio));
 
+	if (zswap_never_enabled())
+		return false;
+
 	if (!zswap_enabled)
 		goto check_old;
 
-- 
2.55.0