Re: [Qemu-devel] [PATCH V19 06/12] quorum: Add quorum mechanism.

[Kevin Wolf]

Am 21.02.2014 um 23:30 hat Benoît Canet geschrieben:
> The Friday 21 Feb 2014 à 15:09:42 (-0700), Eric Blake wrote :
> > On 02/21/2014 02:21 PM, Benoît Canet wrote:
> > > From: Benoît Canet <address@hidden>
> > > 
> > > This patchset enables the core of the quorum mechanism.
> > > The num_children reads are compared to get the majority version and if 
> > > this
> > > version exists more than threshold times the guest won't see the error at 
> > > all.
> > 
> > > +++ b/docs/qmp/qmp-events.txt
> > > @@ -500,3 +500,39 @@ Example:
> > >  
> > >  Note: If action is "reset", "shutdown", or "pause" the WATCHDOG event is
> > >  followed respectively by the RESET, SHUTDOWN, or STOP events.
> > > +
> > > +QUORUM_FAILURE
> > > +--------------
> > 
> > This should have been inserted in sorted order to match the rest of the
> > file, rather than at the end.  Can be rearranged in a followup patch,
> > now that this series is queued.
> > 
> > > +
> > > +Emitted by the Quorum block driver if it fails to establish a quorum.
> > > +
> > > +Data:
> > > +
> > > +- "reference":    device name if defined else node name.
> > > +- "sector-num":   Number of the first sector of the failed read 
> > > operation.
> > 
> > I'm assuming sector-num is relative to the guest's view of the data?
> Yes,

To be more precise: It's the sector number specified by the layer above
quorum. This can be the guest, but in a different configuration it could
be another block driver.

> > > +
> > > +QUORUM_REPORT_BAD
> > > +-----------------
> > > +
> > > +Emitted to report a corruption of a Quorum file.
> > > +
> > > +Data:
> > > +
> > > +- "ret":          The IO return code.
> > 
> > What values is this likely to contain?  Is it a finite set, in which
> > case it would be nice to have a QAPI enum that describes the set of
> > return codes, rather than a raw number?
> 
> It's anything that the block stack could return as an error.

In other words, it's meaning depends on the host and the value is only
suitable for human readers. Perhaps we could change this to strerror(),
which is, I believe, the same as error_setg_errno() does.

Kevin