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From:   Kanchan Joshi <joshiiitr@gmail.com>
Date:   Thu, 28 Jan 2021 22:55:41 +0530
Message-ID: <CA+1E3rLD2e4yFsA-gxPGtp2Fg2Z0sdfpS3Rz+WsUC4i5aF43LA@mail.gmail.com>
Subject: Re: [RFC PATCH 0/4] Asynchronous passthrough ioctl
To:     Jens Axboe <axboe@kernel.dk>
Cc:     Pavel Begunkov <asml.silence@gmail.com>,
        Kanchan Joshi <joshi.k@samsung.com>,
        Keith Busch <kbusch@kernel.org>,
        Christoph Hellwig <hch@lst.de>, sagi@grimberg.me,
        linux-nvme@lists.infradead.org, io-uring@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
        Javier Gonzalez <javier.gonz@samsung.com>,
        Nitesh Shetty <nj.shetty@samsung.com>, anuj20.g@samsung.com
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On Thu, Jan 28, 2021 at 8:20 PM Jens Axboe <axboe@kernel.dk> wrote:
>
> On 1/28/21 5:04 AM, Kanchan Joshi wrote:
> > And for some ioctls, driver may still need to use task-work to update
> > the user-space pointers (embedded in uring/ioctl cmd) during
> > completion.
>
> For this use case, we should ensure that just io_uring handles this
> part. It's already got everything setup for it, and I'd rather avoid
> having drivers touch any of those parts. Could be done by having an
> io_uring helper ala:
>
> io_uring_cmd_complete_in_task(cmd, handler);
>
> which takes care of the nitty gritty details.

Ah right. With that, I can do away with exporting task-work.
NVMe completion can invoke (depending on ioctl) this uring-helper with
a handler that does the ioctl-specific update in task context.


-- 
Kanchan