From: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Date: Tue, 2 Apr 2013 02:46:13 +0000 (+0800)
Subject: staging: zcache: introduce zero-filled pages handler
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=bdcde42d74a12e170971038671a80ef00603ae4e;p=linux-beck.git

staging: zcache: introduce zero-filled pages handler

Introduce zero-filled pages handler to capture and handle zero pages.

Acked-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Signed-off-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/staging/zcache/zcache-main.c b/drivers/staging/zcache/zcache-main.c
index fb699df30713..274a48e94cfe 100644
--- a/drivers/staging/zcache/zcache-main.c
+++ b/drivers/staging/zcache/zcache-main.c
@@ -277,6 +277,33 @@ static void zcache_obj_free(struct tmem_obj *obj, struct tmem_pool *pool)
 	kmem_cache_free(zcache_obj_cache, obj);
 }
 
+static bool page_is_zero_filled(void *ptr)
+{
+	unsigned int pos;
+	unsigned long *page;
+
+	page = (unsigned long *)ptr;
+
+	for (pos = 0; pos < PAGE_SIZE / sizeof(*page); pos++) {
+		if (page[pos])
+			return false;
+	}
+
+	return true;
+}
+
+static void handle_zero_filled_page(void *p)
+{
+	void *user_mem;
+	struct page *page = (struct page *)p;
+
+	user_mem = kmap_atomic(page);
+	memset(user_mem, 0, PAGE_SIZE);
+	kunmap_atomic(user_mem);
+
+	flush_dcache_page(page);
+}
+
 static struct tmem_hostops zcache_hostops = {
 	.obj_alloc = zcache_obj_alloc,
 	.obj_free = zcache_obj_free,