eCryptfs: Gracefully refuse miscdev file ops on inherited/passed files
From: Colin Ian King <firstname.lastname@example.org>
File operations on /dev/ecryptfs would BUG() when the operations were
performed by processes other than the process that originally opened the
file. This could happen with open files inherited after fork() or file
descriptors passed through IPC mechanisms.
upstream cherry pick of commit 8dc6780587c99286c0d3de747a2946a76989414a