This fcntl requests all cached blocks associated with the minor device
number associated with the regular file are invalidated. If the file
is a block special, invalidate the blocks associated with that minor
device instead.
This is to be used for a test that tests unmapped file-mapped memory
ranges whose blocks are not in the cache and therefore must be fetched
from a FS.
Change-Id: Ide914b2e88413aa90bd731ae587ca06fa5f13ebc
58b8ff5ffa