zram: use copy_page for full page copy

Some architectures, such as arm, have implemented optimized copy_page for
full page copying.

Replace the full page memcpy with copy_page to take advantage of the
optimization.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Mark-PK Tsai <[email protected]>
Reviewed-by: Sergey Senozhatsky <[email protected]>
Cc: AngeloGioacchino Del Regno <[email protected]>
Cc: Jens Axboe <[email protected]>
Cc: Matthias Brugger <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: YJ Chiang <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: NotZeetaa <[email protected]>
Signed-off-by: Pajdek <[email protected]>

drivers/block/zram/zram_drv.c

@@ -1494,7 +1494,7 @@ static int __zram_bvec_read(struct zram *zram, struct page *page, u32 index,
 			    zram_entry_handle(zram, entry), ZS_MM_RO);
 	if (size == PAGE_SIZE) {
 		dst = kmap_atomic(page);
-		memcpy(dst, src, PAGE_SIZE);
+		copy_page(dst, src);
 		kunmap_atomic(dst);
 		ret = 0;
 	} else {