f2fs: support IO error injection

This patch adds to support IO error injection for testing IO error
tolerance of f2fs.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/data.c

@@ -34,6 +34,11 @@ static void f2fs_read_end_io(struct bio *bio)
 	struct bio_vec *bvec;
 	int i;
 
+#ifdef CONFIG_F2FS_FAULT_INJECTION
+	if (time_to_inject(FAULT_IO))
+		bio->bi_error = -EIO;
+#endif
+
 	if (f2fs_bio_encrypted(bio)) {
 		if (bio->bi_error) {
 			fscrypt_release_ctx(bio->bi_private);