Function default_vfs_ioctl 

pub fn default_vfs_ioctl(
    file: &FileObject,
    locked: &mut Locked<Unlocked>,
    current_task: &CurrentTask,
    request: u32,
    arg: SyscallArg,
) -> Result<Option<SyscallResult>, Errno>

Universal VFS ioctl dispatcher for FileObject.

Handles generic file system ioctls (such as non-blocking mode toggles, block size queries, and file cloning) at the VFS layer without delegating to underlying device drivers.

Returns Some(result) if the ioctl command is handled by the VFS layer, or None if the command is unhandled and should be dispatched to FileOps::ioctl.