NFSD: Flesh out a documenting comment for filecache.c

Record what we've learned recently about the NFSD filecache in a
documenting comment so our future selves don't forget what all this
is for.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
This commit is contained in:
Chuck Lever 2022-11-01 13:30:46 -04:00
commit b3276c1f5b