Opening a /srv file sets the close-on-exec flag on the
shared channel breaking the exportfs openmount() hack.
The devsrv tries to prevent posting a channel with the
close-on-exec or remove-on-close flags. but nothing
currently prevents this poisoning on open.
Until this gets fixed in eigther exportfs or devsrv,
i'll back out the changes that could have potential side
effects like this.
The mount() and bind() syscalls return -1 on error,
and the mountid sequence number on success.
The manpage states that the mountid sequence number
is a positive integer, but the kernels implementation
currently uses a unsigned 32-bit integer and does not
guarantee that the mountid will not become negative.
Most code just cares about the error, so test for
the -1 error value only.