It appears that if I mount /dev/wd0e on /mnt, and /dev is a tmpfs, changes
in /mnt are not flushed to wd0a.  Instead, dirty blocks linger until I
unmount /mnt.  I first noticed this because all of my tmpfs filesystems
showed 0 blocks available as I extracted a large .tgz file under /mnt/.

Naively, I wonder if the problem is not tmpfs_sync, which is a no-op.
Comparing with ffs_sync, I see that it will call VOP_FSYNC() on VBLK-type
vnodes.

Dave

-- 
David Young             OJC Technologies
dyoung@ojctech.com      Urbana, IL * (217) 278-3933