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>
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 951b9b3..f28b3f8 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -46,6 +46,7 @@
 	FAULT_BLOCK,
 	FAULT_DIR_DEPTH,
 	FAULT_EVICT_INODE,
+	FAULT_IO,
 	FAULT_MAX,
 };
 
@@ -77,6 +78,8 @@
 		return false;
 	else if (type == FAULT_EVICT_INODE && !IS_FAULT_SET(type))
 		return false;
+	else if (type == FAULT_IO && !IS_FAULT_SET(type))
+		return false;
 
 	atomic_inc(&f2fs_fault.inject_ops);
 	if (atomic_read(&f2fs_fault.inject_ops) >= f2fs_fault.inject_rate) {