f2fs: compress: remove unneeded read when rewrite whole cluster

when we overwrite the whole page in cluster, we don't need read original
data before write, because after write_end(), writepages() can help to
load left data in that cluster.
Signed-off-by: Fengnan Chang <changfengnan@vivo.com>
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Acked-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/data.c

@@ -3329,6 +3329,9 @@ static int f2fs_write_begin(struct file *file, struct address_space *mapping,
 
 		*fsdata = NULL;
 
+		if (len == PAGE_SIZE)
+			goto repeat;
+
 		ret = f2fs_prepare_compress_overwrite(inode, pagep,
 							index, fsdata);
 		if (ret < 0) {