alloc_empty_file
file = alloc_empty_file(flags, current_cred());
struct file *alloc_empty_file(int flags, const struct cred *cred);
file = alloc_empty_file(op->open_flag, current_cred());
file = alloc_empty_file(flags, cred);
f = alloc_empty_file(flags, cred);
struct file *f = alloc_empty_file(flags, cred);