Trait for extracting file open arguments from kernel data structures.
This is meant to be implemented by registration managers.
The type of argument this adapter extracts.
Converts untyped data stored in [
struct inode] and [
struct file] (when [
struct file_operations::open] is called) into the given type. For example, for
devices, a pointer to the registered [
struct miscdev] is stored in [
This function must be called only when [
struct file_operations::open] is being called for
a file that was registered by the implementer.