ZFS v28 and sendfile()

[Rob Farmer]

Seems to not work properly, at least as implemented in the nginx web
server (specifically www/nginx-devel from ports).

I have "sendfile on;" in my nginx.conf and files served from a ZFS
filesystem are garbled in seemingly random ways (their md5 changes
every time). Shutting it off resolves the problem. Using sendfile with
a UFS partition on the same machine causes no problems.

-- 
Rob Farmer