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Date:   Tue, 29 Jun 2021 14:59:09 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Martin Wilck <mwilck@suse.com>
Cc:     Christoph Hellwig <hch@lst.de>, Mike Snitzer <snitzer@redhat.com>,
        Alasdair G Kergon <agk@redhat.com>,
        Bart Van Assche <Bart.VanAssche@sandisk.com>,
        "Martin K. Petersen" <martin.petersen@oracle.com>,
        linux-scsi@vger.kernel.org, dm-devel@redhat.com,
        Hannes Reinecke <hare@suse.de>,
        Daniel Wagner <dwagner@suse.de>, linux-block@vger.kernel.org,
        Paolo Bonzini <pbonzini@redhat.com>,
        Benjamin Marzinski <bmarzins@redhat.com>, nkoenig@redhat.com,
        emilne@redhat.com
Subject: Re: [PATCH v4 1/3] scsi: scsi_ioctl: export
 __scsi_result_to_blk_status()
Message-ID: <20210629125909.GB14372@lst.de>
References: <20210628095210.26249-1-mwilck@suse.com> <20210628095210.26249-2-mwilck@suse.com> <20210628095341.GA4105@lst.de> <4fb99309463052355bb8fefe034a320085acab1b.camel@suse.com>
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On Mon, Jun 28, 2021 at 04:57:33PM +0200, Martin Wilck wrote:
> Hello Christoph,
> 
> On Mo, 2021-06-28 at 11:53 +0200, Christoph Hellwig wrote:
> > On Mon, Jun 28, 2021 at 11:52:08AM +0200, mwilck@suse.com wrote:
> > > From: Martin Wilck <mwilck@suse.com>
> > > 
> > > This makes it possible to use scsi_result_to_blk_status() from
> > > code that shouldn't depend on scsi_mod (e.g. device mapper).
> > 
> > This really has no business being used outside of low-level SCSI
> > code.
> 
> And this is where my patch set uses it. Can you recommend a better
> way how to access this algorithm, without making dm_mod.ko or dm-
> mpath.ko depend on scsi_mod.ko, and without open-coding it
> independently in a different code path?

> The sg_io-on-multipath code needs to answer the question "is this a
> path or a target error?". Therefore it calls blk_path_error(), which
> requires obtaining a blk_status_t first. But that's not available in
> the sg_io code path. So how should I deal with this situation?

Not by exporting random crap from the SCSI code.