Re: dm: Integrity errors should not cause failover

[Mike Snitzer <snitzer@redhat.com>]

On Wed, May 18 2011 at  8:11am -0400,
Mike Snitzer <snitzer@redhat.com> wrote:

> On Wed, May 18 2011 at 12:49am -0400,
> Martin K. Petersen <martin.petersen@oracle.com> wrote:
> 
> > 
> > Integrity errors need to be passed to the owner of the integrity
> > metadata for processing. Consequently EILSEQ should be passed up the
> > stack.
> > 
> > Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
> > Acked-by: Mike Snitzer <snitzer@redhat.com>
> > 
> > ---
> > 
> > Ping on this one?
> 
> It has been on my personal queue but I didn't push the issue with
> Alasdair (for 2.6.39).
> 
> At this point seems we should be targetting this fix for 2.6.40 but I'll
> defer to Alasdair on whether he'd like to push to .39 last minute.

Hi Martin,

Alasdair and I just chatted about this patch: it will always pass the
the -EILSEQ up _without_ performing any mpath path failure.

The newfound concern is: is there ever a benefit to failing the path
before returning -EILSEQ?

Or will -EILSEQ always imply there is nothing wrong with the path?
E.g. a transport error cannot cause a CRC error -- the transport
error is always trapped by SCSI and cannot result in continued
processing of an IO (that goes on to have CRC error)?

Thanks,
Mike

> 
> > diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
> > index a550a05..aa4e570 100644
> > --- a/drivers/md/dm-mpath.c
> > +++ b/drivers/md/dm-mpath.c
> > @@ -1290,7 +1290,7 @@ static int do_end_io(struct multipath *m, struct request *clone,
> >  	if (!error && !clone->errors)
> >  		return 0;	/* I/O complete */
> >  
> > -	if (error == -EOPNOTSUPP || error == -EREMOTEIO)
> > +	if (error == -EOPNOTSUPP || error == -EREMOTEIO || error == -EILSEQ)
> >  		return error;
> >  
> >  	if (mpio->pgpath)
> 
> --
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