[illumos-Developer] MUCH better --> zil for zvol TRUNCATE (and iSCSI UNMAP) working...

[Garrett D'Amore]

I'm not sure your code unmap review is up to date:

sbd.c: line 3845 & 3846... a residual #if 0 and the KEBE ASKS comment.
sbd.c: line 3757 -- I thought you were issuing these against /dev/zvol?

Can you please check to make sure your webrev is updated?

	- Garrett

On Tue, 2011-03-01 at 12:31 -0500, Dan McDonald wrote:
> George gave me a few things to try (which I've numbered and quoted):
> 
> > 1.) So I would recommend setting a breakpoint after zvol_log_truncate() and
> >     forcing a panic.  Then make sure that we process this ioctl again on
> >     bootup.
> 
> We talked about this already, and forcing the reboot after zil_commit()
> causes the right thing to happen.
> 
> > 2.) Also do the same thing after dmu_free_long_range().
> 
> See above.
> 
> > 3.) But you'll want to add another reboot point in zvol_replay_truncate()
> >     prior to calling dmu_free_long_range() and also after it. What we need
> >     to see is that zvol_replay_truncate() is called after these reboot
> >     points. If they are then we're still replaying the same log block on
> >     disk and we can leave the code the same. Make sense?
> 
> Every time I rebooted in the *middle* of zvol_replay_truncate(), the
> rebooting system (once COMSTAR starts and attmempts to open the zvol) would
> drop into zvol_replay_truncate() again, no matter where I rebooted within the
> function (including JUST before an otherwise successful return).
> 
> I think we're doing the right thing w.r.t. the zvol.  As I mentioned before,
> my client UNMAPs in chunks of 8MB where possible, so for sufficiently large
> files (like my original 128MB test tarball) I've only be able to catch the
> first 8MB chunk.
> 
> So with that, I submit that this webrev:
> 
> 	http://www.kebe.com/~danmcd/webrevs/unmap/
> 
> might be fit for consumption by Illumos.  I still defer to reviewers with
> more ZFS clue than me, but this has been a good learning experience.
> 
> Thanks!
> Dan
> 
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