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Date:   Wed, 31 May 2023 16:17:39 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Johannes Thumshirn <Johannes.Thumshirn@wdc.com>
Cc:     Christoph Hellwig <hch@lst.de>, Qu Wenruo <quwenruo.btrfs@gmx.com>,
        Naohiro Aota <Naohiro.Aota@wdc.com>,
        "linux-btrfs@vger.kernel.org" <linux-btrfs@vger.kernel.org>
Subject: Re: new scrub code vs zoned file systems
Message-ID: <20230531141739.GA2160@lst.de>
References: <20230531125224.GB27468@lst.de> <546fad79-f436-c561-8b9b-0d9a7db09522@wdc.com> <20230531132032.GA30016@lst.de> <821003e3-b457-90ba-e733-8c2fdd0c3b3c@wdc.com> <20230531133038.GA30855@lst.de> <a59b2274-9d64-f11e-f726-9283f560a495@wdc.com>
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On Wed, May 31, 2023 at 02:04:05PM +0000, Johannes Thumshirn wrote:
> 
> Heh and this has never actually worked IMHO.
> 
> I did a crude hack to bandaid scrub:

I think the better approach is to:

 a) branch out at a very high level to the zoned code in
    flush_scrub_stripes, or in fact even higher given that we
    don't really care about tracking stripes.  The write
    side of scrub has to work at a zone, not stripe level for
    zoned devices
 b) don't create a new relocation thread per zone, but run it from
    the scrub context.