From ae34af1f11d0a6ae849b7605d15df9798dab7b46 Mon Sep 17 00:00:00 2001 From: Miaohe Lin Date: Wed, 30 Jun 2021 18:52:52 -0700 Subject: [PATCH] mm/zswap.c: avoid unnecessary copy-in at map time The buf mapped via zpool_map_handle() is only used to store compressed page buffer and there is no information to extract from it. So we could use ZPOOL_MM_WO instead to avoid unnecessary copy-in at map time. Link: https://lkml.kernel.org/r/20210522092242.3233191-3-linmiaohe@huawei.com Signed-off-by: Miaohe Lin Cc: Colin Ian King Cc: Dan Streetman Cc: Nathan Chancellor Cc: Sebastian Andrzej Siewior Cc: Seth Jennings Cc: Tian Tao Cc: Vitaly Wool Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/zswap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/zswap.c b/mm/zswap.c index e934593..c27ce9f 100644 --- a/mm/zswap.c +++ b/mm/zswap.c @@ -1203,7 +1203,7 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset, zswap_reject_alloc_fail++; goto put_dstmem; } - buf = zpool_map_handle(entry->pool->zpool, handle, ZPOOL_MM_RW); + buf = zpool_map_handle(entry->pool->zpool, handle, ZPOOL_MM_WO); memcpy(buf, &zhdr, hlen); memcpy(buf + hlen, dst, dlen); zpool_unmap_handle(entry->pool->zpool, handle); -- 2.7.4