v4.19.13 snapshot.
diff --git a/lib/notifier-error-inject.c b/lib/notifier-error-inject.c
new file mode 100644
index 0000000..eb4a04a
--- /dev/null
+++ b/lib/notifier-error-inject.c
@@ -0,0 +1,112 @@
+#include <linux/module.h>
+
+#include "notifier-error-inject.h"
+
+static int debugfs_errno_set(void *data, u64 val)
+{
+ *(int *)data = clamp_t(int, val, -MAX_ERRNO, 0);
+ return 0;
+}
+
+static int debugfs_errno_get(void *data, u64 *val)
+{
+ *val = *(int *)data;
+ return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(fops_errno, debugfs_errno_get, debugfs_errno_set,
+ "%lld\n");
+
+static struct dentry *debugfs_create_errno(const char *name, umode_t mode,
+ struct dentry *parent, int *value)
+{
+ return debugfs_create_file(name, mode, parent, value, &fops_errno);
+}
+
+static int notifier_err_inject_callback(struct notifier_block *nb,
+ unsigned long val, void *p)
+{
+ int err = 0;
+ struct notifier_err_inject *err_inject =
+ container_of(nb, struct notifier_err_inject, nb);
+ struct notifier_err_inject_action *action;
+
+ for (action = err_inject->actions; action->name; action++) {
+ if (action->val == val) {
+ err = action->error;
+ break;
+ }
+ }
+ if (err)
+ pr_info("Injecting error (%d) to %s\n", err, action->name);
+
+ return notifier_from_errno(err);
+}
+
+struct dentry *notifier_err_inject_dir;
+EXPORT_SYMBOL_GPL(notifier_err_inject_dir);
+
+struct dentry *notifier_err_inject_init(const char *name, struct dentry *parent,
+ struct notifier_err_inject *err_inject, int priority)
+{
+ struct notifier_err_inject_action *action;
+ umode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
+ struct dentry *dir;
+ struct dentry *actions_dir;
+
+ err_inject->nb.notifier_call = notifier_err_inject_callback;
+ err_inject->nb.priority = priority;
+
+ dir = debugfs_create_dir(name, parent);
+ if (!dir)
+ return ERR_PTR(-ENOMEM);
+
+ actions_dir = debugfs_create_dir("actions", dir);
+ if (!actions_dir)
+ goto fail;
+
+ for (action = err_inject->actions; action->name; action++) {
+ struct dentry *action_dir;
+
+ action_dir = debugfs_create_dir(action->name, actions_dir);
+ if (!action_dir)
+ goto fail;
+
+ /*
+ * Create debugfs r/w file containing action->error. If
+ * notifier call chain is called with action->val, it will
+ * fail with the error code
+ */
+ if (!debugfs_create_errno("error", mode, action_dir,
+ &action->error))
+ goto fail;
+ }
+ return dir;
+fail:
+ debugfs_remove_recursive(dir);
+ return ERR_PTR(-ENOMEM);
+}
+EXPORT_SYMBOL_GPL(notifier_err_inject_init);
+
+static int __init err_inject_init(void)
+{
+ notifier_err_inject_dir =
+ debugfs_create_dir("notifier-error-inject", NULL);
+
+ if (!notifier_err_inject_dir)
+ return -ENOMEM;
+
+ return 0;
+}
+
+static void __exit err_inject_exit(void)
+{
+ debugfs_remove_recursive(notifier_err_inject_dir);
+}
+
+module_init(err_inject_init);
+module_exit(err_inject_exit);
+
+MODULE_DESCRIPTION("Notifier error injection module");
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Akinobu Mita <akinobu.mita@gmail.com>");