f2fs: avoid grab_cache_page_write_begin for data pages

We don't need to wait on page writeback for these cases.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 9160610..6f1a9e2 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -424,7 +424,7 @@
 	if (unlikely(dn.data_blkaddr == NEW_ADDR))
 		return ERR_PTR(-EINVAL);
 
-	page = grab_cache_page_write_begin(mapping, index, AOP_FLAG_NOFS);
+	page = grab_cache_page(mapping, index);
 	if (!page)
 		return ERR_PTR(-ENOMEM);
 
@@ -462,7 +462,7 @@
 	int err;
 
 repeat:
-	page = grab_cache_page_write_begin(mapping, index, AOP_FLAG_NOFS);
+	page = grab_cache_page(mapping, index);
 	if (!page)
 		return ERR_PTR(-ENOMEM);