Re: [dm-devel] [PATCH v4 1/3] scsi: scsi_ioctl: export __scsi_result_to_blk_status()

From: Mike Snitzer <snitzer@gmail.com>
To: Martin Wilck <mwilck@suse.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>,
	linux-scsi@vger.kernel.org, Daniel Wagner <dwagner@suse.de>,
	emilne@redhat.com, linux-block@vger.kernel.org,
	dm-devel@redhat.com, Paolo Bonzini <pbonzini@redhat.com>,
	nkoenig@redhat.com, Bart Van Assche <Bart.VanAssche@sandisk.com>,
	Christoph Hellwig <hch@lst.de>,
	Alasdair G Kergon <agk@redhat.com>
Subject: Re: [dm-devel] [PATCH v4 1/3] scsi: scsi_ioctl: export __scsi_result_to_blk_status()
Date: Wed, 30 Jun 2021 12:01:45 -0400	[thread overview]
Message-ID: <YNyVafnX09cOIZPe@redhat.com> (raw)
In-Reply-To: <1aa1f875e7a85f9a331e88e4f8482588176bdb3a.camel@suse.com>

On Wed, Jun 30 2021 at  4:12P -0400,
Martin Wilck <mwilck@suse.com> wrote:

> On Di, 2021-06-29 at 14:23 -0700, Keith Busch wrote:
> > On Tue, Jun 29, 2021 at 09:23:18PM +0200, Martin Wilck wrote:
> > > On Di, 2021-06-29 at 14:59 +0200, Christoph Hellwig wrote:
> > > > On Mon, Jun 28, 2021 at 04:57:33PM +0200, Martin Wilck wrote:
> > > > 
> > > > > 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.

Helpful as always Christoph... ;)

> > > So, you'd prefer inlining scsi_result_to_blk_status()?
> > 
> > I don't think you need to. The only scsi_result_to_blk_status()
> > caller
> > is sg_io_to_blk_status(). That's already in the same file as
> > scsi_result_to_blk_status() so no need to export it. You could even
> > make
> > it static.
> 
> Thanks for your suggestion. I'd be lucky if this was true. But the most
> important users of scsi_result_to_blk_status() are in scsi_lib.c
> (scsi_io_completion_action(), scsi_io_completion_nz_result()).
> 
> If I move scsi_result_to_blk_status() to vmlinux without exporting it,
> it won't be available in the SCSI core any more, at least not with
> CONFIG_SCSI=m.

For what you're trying to accomplish with this patchset, you only need
sg_io_to_blk_status() exported.

So check with Martin and/or Bart on the best way to give
sg_io_to_blk_status() access to the equivalent of your
__scsi_result_to_blk_status() without exporting it.

I'd start by just folding patches 1 and 2, fixing up the logic Dan
Carpenter pointed ouit, and only exporting sg_io_to_blk_status().

Mike

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