[PATCH] dm: Integrity errors should not cause failover

[PATCH] dm: Integrity errors should not cause failover

[Martin K. Petersen]

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?

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)

Re: dm: Integrity errors should not cause failover

[Mike Snitzer]

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.

> 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)

Re: dm: Integrity errors should not cause failover

[Mike Snitzer]

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)
> 
> --
> dm-devel mailing list
> dm-devel@redhat.com
> https://www.redhat.com/mailman/listinfo/dm-devel

Re: dm: Integrity errors should not cause failover

[Martin K. Petersen]

>>>>> "Mike" == Mike Snitzer <snitzer@redhat.com> writes:

Mike,

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

Correct.


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

No, never.


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

-EILSEQ is only returned if a discrepancy is detected between data and
protection information. In both cases the block in question was
successfully received by either initiator or target. I.e. the path is
working fine.

-- 
Martin K. Petersen	Oracle Linux Engineering

[PATCH] dm: Integrity errors should not cause failover

[Martin K. Petersen]

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>

---

diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index f336c69..57f7dd3 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -1215,7 +1215,7 @@ static int do_end_io(struct multipath *m, struct request *clone,
 	if (!error && !clone->errors)
 		return 0;	/* I/O complete */
 
-	if (error == -EOPNOTSUPP)
+	if (error == -EOPNOTSUPP || error == -EILSEQ)
 		return error;
 
 	if (mpio->pgpath)