Question about dentry cache in VFS

[Martin Peck <coderman@gmail.com>]

I am working on a userspace filesystem and would like
the ability to selectively decache inodes and their children
from the VFS.

I can do this on a global scale using invalidate_inodes() and
shrink_dcache_sb(), however, I would also like to be able
to decache for specific inodes/entries.

One possibility (and perhaps the 'right' way) to do this which
I had considered is using dentry_operations to trap d_revalidate
as needed, however, I would like to avoid an invocation here
for every dentry if there is another way to selectively decache.

Thanks in advance,