[PATCH] zram: use copy_page for full page copy

[Jisheng Zhang <jszhang@kernel.org>]

commit 42e99bd975fd ("zram: optimize memory operations with
clear_page()/copy_page()") optimize page copy/clean operations, but
then commit d72e9a7a93e4 ("zram: do not use copy_page with non-page
aligned address") removes the optimization because there's memory
corruption at that time, the reason was well explained. But after
commit 1f7319c74275 ("zram: partial IO refactoring"), partial IO uses
alloc_page() instead of kmalloc to allocate a page, so we can bring
back the optimization.

commit 80ba4caf8ba9 ("zram: use copy_page for full page copy") brings
back partial optimization, missed one point in zram_write_page().
optimize the full page copying in zram_write_page() with copy_page()

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
---
 drivers/block/zram/zram_drv.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 3acd7006ad2c..4b2b5098062f 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -1478,11 +1478,13 @@ static int zram_write_page(struct zram *zram, struct page *page, u32 index)
 	dst = zs_map_object(zram->mem_pool, handle, ZS_MM_WO);
 
 	src = zstrm->buffer;
-	if (comp_len == PAGE_SIZE)
+	if (comp_len == PAGE_SIZE) {
 		src = kmap_local_page(page);
-	memcpy(dst, src, comp_len);
-	if (comp_len == PAGE_SIZE)
+		copy_page(dst, src);
 		kunmap_local(src);
+	} else {
+		memcpy(dst, src, comp_len);
+	}
 
 	zcomp_stream_put(zram->comps[ZRAM_PRIMARY_COMP]);
 	zs_unmap_object(zram->mem_pool, handle);
-- 
2.43.0