GENERIC make buildkernel error / fails - posix_fadvise

[Rob Clark]

System: Dell 600sc
Currently running: 8.2-RELEASE

In attempting to update this system to 8-STABLE I did
what I usually do to update a system (see below).
make buildworld completes successfully, but make
buildkernel does not. I usually create a custom
kernel, but for this system I went with GENERIC as
is.  

The error message is: 
/usr/src/sys/kern/init_sysent.c:568: error: invalid
application of 'sizeof' to incomplete type 'struct
posix_fadvise_args' /usr/src/sys/kern/init_sysent.c:568:
error: 'posix_fadvise' undeclared here (not in a
function) *** Error code 1

I found this pertaining to
posix_fadvise in /usr/src/UPDATING: 
20120106:
A new VOP_ADVISE() was added to support
posix_fadvise(2).  All filesystem modules must be
recompiled.

Not sure what 'filesystem modules' is or referring to
here. Also, am I not already recompiling 'All
filesystem modules' during make buildworld?

What I did (and usually do):
csup -L 2 /root/stable-supfile 
rm -rf /etc.old cp -Rp /etc /etc.old 
adjkerntz -i
cd /usr/obj
chflags -R noschg *
rm -rf *
cd /usr/src
/usr/bin/time -h make buildworld || exit

build world finishes successfully.
 
Then:
cd /usr/src
make buildkernel KERNCONF=GENERIC
make installkernel KERNCONF=GENERIC

This fails with error:
/usr/src/sys/kern/init_sysent.c:568: error: invalid
application of 'sizeof' to incomplete type 'struct
posix_fadvise_args' /usr/src/sys/kern/init_sysent.c:568:
error: 'posix_fadvise' undeclared here (not in a
function) *** Error code 1

Stop in /usr/obj/usr/src/sys/GENERIC.
*** Error code 1

Stop in /usr/src.
*** Error code 1

Stop in /usr/src.

Following attempts:

Attempt 2:
I tried using 'make buildkernel' (without
specifying KERNCONF) make buildkernel fails with
same error.

Attempt 3:
Started from the beginning (same process as above)
with new csup (sources) -- make buildkernel still
failed with same error.

Any help here would be greatly appreciated.
In way over my head here. I have all logs from all
attempts of the above if needed.  

Thanks,
Rob Clark
<rpclark at tds.net>