In contrast, the *BSD* (etc) VFS has a GETATTR operation that allows the
filesystem to intervene at this point. In fact, this observation came up
in thinking about how some code written to that interface would work in
Linux.
As far as I can tell, fstat is the only case where the kernel might use an
inode without giving the filesystem layer some chance to update the inode
information. Note that stat, for example, is not afflicted by the same
problem: it does a lookup VFS operation to find the inode of interest.
The lookup operation can revalidate the looked-up inode before returning
it. (This is what Linux NFS does, for example.)
Michael