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Date:   Sat, 17 Apr 2021 11:39:29 +0900
From:   Keith Busch <kbusch@kernel.org>
To:     Casey Chen <cachen@purestorage.com>
Cc:     axboe@kernel.dk, hch@lst.de, linux-block@vger.kernel.org,
        linux-nvme@lists.infradead.org, sagi@grimberg.me,
        yzhong@purestorage.com
Subject: Re: [PATCH 2/2] nvme: use return value from blk_execute_rq()
Message-ID: <20210417023929.GD32082@redsun51.ssa.fujisawa.hgst.com>
References: <CALCePG0y1REA8xXX1ymTwAZhrbSyUh41zfpOmFQViuyPGf5ePg@mail.gmail.com>
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On Fri, Apr 16, 2021 at 07:04:34PM -0700, Casey Chen wrote:
> > On Fri, Apr 16, 2021 at 10:12:11AM -0700, Yuanyuan Zhong wrote:
> > > >         if (poll)
> > > >                 nvme_execute_rq_polled(req->q, NULL, req, at_head);
> > > You may need to audit other completion handlers for blk_execute_rq_nowait().
> >
> > Why? Those callers already provide their own callback that directly get
> > the error.
> 
> We should make sure all callbacks provided to blk_execute_rq_nowait()
> carry error back. i.e. by reusing rq->end_io_data.
>
> > > How to get error ret from polled rq?
> >
> > Please see nvme_end_sync_rq() for that driver's polled handler callback.
> > It already has the error.
> 
> nvme_end_sync_rq() currently doesn't store error in rq->end_io_data as
> you proposed in patch 1.

The question was how the error gets back to the caller, and they already
have it.

Patch 1 is specific to the sync execution. All the async users' handling
of the provided error are implementation specific. If they're not using
it correctly, then they can be fixed too.