From mboxrd@z Thu Jan  1 00:00:00 1970
From: Mike Snitzer <snitzer@redhat.com>
Subject: Re: scsi_error: do not allow IO errors with certain ILLEGAL_REQUEST
 sense to be retryable
Date: Tue, 6 Dec 2011 17:42:19 -0500
Message-ID: <20111206224218.GA31543@redhat.com>
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To: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: linux-scsi@vger.kernel.org, James Bottomley <jbottomley@parallels.com>, Hannes Reinecke <hare@suse.de>

On Tue, Dec 06 2011 at  5:03pm -0500,
Martin K. Petersen <martin.petersen@oracle.com> wrote:

> >>>>> "Mike" == Mike Snitzer <snitzer@redhat.com> writes:
> 
> Mike> Regardless, shouldn't the SCSI midlayer classify such
> Mike> ILLEGAL_REQUEST sense, with an add. sense I listed in the patch,
> Mike> as a target error?
> 
> Well, even SUCCESS should cause the I/O to be aborted.

As I replied to James, yes SUCCESS does cause the IO to fail, but the
discard gets retried by multipath.

Returning TARGET_ERROR enables the block layer to return -EREMOTEIO
which multipath will immediately pass up (rather than the normal fail
path and retry).
 
> I assume this is the RHEL6 kernel? Did you backport my provisioning
> updates that brings the heuristics in sync with SBC-3 (#c98a0e)?

Yes, that update was pulled in to RHEL6.2 (released today).  But this
issue is a concern for both upstream and RHEL6 (and any other distro
with a recent kernel).