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From:   Kanchan Joshi <joshiiitr@gmail.com>
Date:   Fri, 10 Jul 2020 18:59:45 +0530
Message-ID: <CA+1E3rJSiS58TE=hHv5wVv-umJ19_7zKv-JqZTNzD=xi3MoX1g@mail.gmail.com>
Subject: Re: [PATCH v3 4/4] io_uring: add support for zone-append
To:     Christoph Hellwig <hch@infradead.org>
Cc:     Jens Axboe <axboe@kernel.dk>, Kanchan Joshi <joshi.k@samsung.com>,
        viro@zeniv.linux.org.uk, bcrl@kvack.org, Damien.LeMoal@wdc.com,
        asml.silence@gmail.com, linux-fsdevel@vger.kernel.org,
        "Matias Bj??rling" <mb@lightnvm.io>, linux-kernel@vger.kernel.org,
        linux-aio@kvack.org, io-uring@vger.kernel.org,
        linux-block@vger.kernel.org,
        Selvakumar S <selvakuma.s1@samsung.com>,
        Nitesh Shetty <nj.shetty@samsung.com>,
        Javier Gonzalez <javier.gonz@samsung.com>
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On Fri, Jul 10, 2020 at 6:39 PM Christoph Hellwig <hch@infradead.org> wrote:
>
> On Thu, Jul 09, 2020 at 12:50:27PM -0600, Jens Axboe wrote:
> > It might, if you have IRQ context for the completion. task_work isn't
> > expensive, however. It's not like a thread offload.
> >
> > > Using flags have not been liked here, but given the upheaval involved so
> > > far I have begun to feel - it was keeping things simple. Should it be
> > > reconsidered?
> >
> > It's definitely worth considering, especially since we can use cflags
> > like Pavel suggested upfront and not need any extra storage. But it
> > brings us back to the 32-bit vs 64-bit discussion, and then using blocks
> > instead of bytes. Which isn't exactly super pretty.
>
> block doesn't work for the case of writes to files that don't have
> to be aligned in any way.  And that I think is the more broadly
> applicable use case than zone append on block devices.

But when can it happen that we do zone-append on a file (zonefs I
asssume), and device returns a location (write-pointer essentially)
which is not in multiple of 512b?


-- 
Joshi