RFC: Pass TRIM through GELI

[Pawel Jakub Dawidek]

On Sun, Jun 28, 2015 at 08:38:41PM -0500, Matthew D. Fuller wrote:
> > > Stuffed into bugzilla as
> > > <https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=198860>
> > [...]
> > > After last round, everybody seems happy enough with this, so I've
> > > filed it as
> > > <https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=198863>.
> > 
> > Does anybody have outstanding concerns on these?  Or, if not, what
> > else do we need to move them along?  They're working fine for me
> > here...
> 
> Ping...   still working fine here, and I'm pretty sure I've addressed
> every concern anybody's raised.

Matthew,

I'm sorry that it took me so long to get to your patch.

The good news is that I like the patch - it looks clean and complete.
The bad news is that I like it a bit too much:) I think I'd prefer that
BIO_DELETE is passed through by default and there is an option to turn
it off. This would mean changing -t option to -T for init and onetime
and renaming the G_ELI_FLAG_DELETE flag to G_ELI_FLAG_IGNORE_DELETE.
OR... just removing the ability to ignore BIO_DELETEs. The latter is
appealing especially if some days we will implement BIO_DELETEs as
overwrites. Then we should have an option to turn that on, which would
turn off TRIM/UNMAP.

Thinking about it some more, I believe that if someone doesn't want
TRIM/UNMAP to hit his SSDs it should be configurable on per-SSD basis
and not on every layer above SSD. So at the end I'd change my preference
to just passing BIO_DELETEs always.

What do you think?

-- 
Pawel Jakub Dawidek                       http://www.wheelsystems.com
FreeBSD committer                         http://www.FreeBSD.org
Am I Evil? Yes, I Am!                     http://mobter.com
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