SU+J on 9.1-RC2 ISO

[Mateusz Guzik]

On Sat, Nov 03, 2012 at 12:27:18AM +0700, Adam Strohl wrote:
> On 11/3/2012 0:13, Mike Jakubik wrote:
> >You can disable SU+J after installing, though it would be nice if the
> >installer gave you a choice.
> 
> This assumes that you know about this flaw, which most people do not.
> 
> I didn't until I discovered it by panic-ing a perfectly fine running
> server.  Getting burned by a known bug like this shouldn't be "SOP"
> for users of FreeBSD.
> 

Currently when you try to take a snapshot, the kernel checks whether SUJ
is enabled on specified mount-point, and if yes it returns EOPNOTSUPP.

See this commit (MFCed as r230725):
http://svnweb.freebsd.org/base?view=revision&revision=230250 

So it's not that bad.

> If anything it should be turned off by default, and people can turn
> it on if they want given the landmine it plants.  If they know how
> to turn it on they're much more likely to be aware of the issue.
> 

That being said, sure, you may run into another bugs, but if SUJ was
enabled by default I guess it was felt that it works well enough (and in
case of known bugs like problems with snapshots just bails out early).

-- 
Mateusz Guzik <mjguzik gmail.com>