f2fs: add fault injection on f2fs_truncate

Inject a fault during f2fs_truncate().

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index b549b53..7c9685c 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -50,6 +50,7 @@ enum {
 	FAULT_BLOCK,
 	FAULT_DIR_DEPTH,
 	FAULT_EVICT_INODE,
+	FAULT_TRUNCATE,
 	FAULT_IO,
 	FAULT_CHECKPOINT,
 	FAULT_MAX,