Deviceid-Scoped Layout Recall for NFSv4.2

The Parallel Network File System (pNFS) allows the metadata server to recall a layout from a client by file id, by file system id, or across all of a client's layouts. It also lets the server delete a deviceid via CB_NOTIFY_DEVICEID. It does not provide a mechanism for the metadata server to recall, in a single operation, all layouts that reference a specific deviceid. This document presents an extension to RFC7862 that adds a deviceid-scoped layout recall: a single CB_LAYOUTRECALL operation recalls every layout a client holds that references a given deviceid, leaving unrelated layouts in place. Without this capability, device unavailability can trigger large volumes of failed WRITE and LAYOUTERROR traffic, and administrators lack a surgical way to retire a deviceid without disturbing layouts that reference healthy devices.